5fv\ u (J •1 ANNEX ■I u <_7ccfovn,....../ ... ... .-. No. S^J>^.^-_ f Worcester eountg ^tfieneum. I f » Af< o DEPOSITED BY *//?£-./& Price, $ cts. A.D. 182^? #: |-#######^####^#.^#^###,^####:| ■> v Ml / ELEMENTS OF CHEMISTRY. u CHEVALIER OF THE ORDER OF THE KING, PROFESSOR Of CHEM* ISTRY AT MONTPEIXIER, HONORARY INSPECTOR OP THE MINES OF FRANCE, AND MEMBER OF SEVERAL ACADE- MIES OF SCIENCES, MEDICINE, AGRICULTURE, IN- SCRIPTIONS, AND BELLES LETTRES. TRANSLATED FROM THE FRENCH. 'SLfifrB amertcan ffiuitton. fHREE rOLUM$$ IN ONE, J BOSTON: PRINTED BY J. T. BUCKINGHAM, FOR THOMAS ts" ANDREWS, NO. 45, NEWBURT-STREET. 1806, rTlO TS^ 5' S* THE great experience of M. Chaptal, his unaffecV ed candour, and the perfpicuity which is feen in every part of the following treatife, cannot but render it extenfively ufefuL I have been particularly careful not to diminifh this laft merit, by deviating in any ret pea from that fcrupulous attention to accuracy which is indiipenfably required to give authority to the trans- lation of a work of fcience. W. NICHOLSON. London, April, 1791. 1 !. rtfi^ :.z ;. r ■ * » - .,■ 't ■ .'' *">* CONTENTS. M ■ ■■ i lagggaiMMa— PART FIRST. CONCERNING THE CHEMICAL PRINCIPLES. INTRODUCTION. DPage EFINITION of Chem'rftry; its Objea and Means.—Defcrip- tion of a Laboratory, and the principal inftruments employed in che- mical operations, with a definition of thofe operations 43 SECTION I. Concerning the general law which tends to bring the particles of bodies together, and to maintain them in a ftate of mixture or com- bination 53 Of the AfRnity of Aggregation 53 Of the Affinity of Compofition 54 SECTION II. Concerning the various means employed by chemifts to overcome the adhefion which exifts between the particles of bodies 6 a SECTION III. Concerning the method of proceeding which the chemifts ought to follow in the ftudy of the various bodies pfefented to us by nature 65 SECTION IV. Concerning Simple or Elementary Subftances 7» Chap. I. Concerning Fire 71 Art. I. Concerning Calorick and Heat 72 Art. II. Concerning Light 8a Chap. II. Concerning Sulphur S4 Chap. Ill- Concerning Carbone 87 SECTION V. Coscerning Gafes, or the folution of certain principles in Calorick ax the Temperature of the Atmofphere 8S Chap. I. Concerning the Hydrogenous Gas, or Inflammable Air 91 VI CONTENTS. Page Chap. H. Concerning Oxigenous Gas, or Vital Air 96 Chap. HI. Concerning Nitrogene Gas, Azote, or Atmofpherical Mephitis 108 , SECTION VI. Concerning the Mixture of Nitrogene and Oxigene Gas ; or of at- raofpherick air Z09 SECTION VII. Concerning the combination of Oxigenous Gas and Hydrogene, which forms Water lit Art. I. Concerning Water in the ftate of Ice ill Art. II. Concerning Water in the liquid ftate 114 Art. HI. Concerning Water in the date of Gas 117 SECTION VIII. Concerning the combinations of Nitrogene Gas. 1. With Hydro- gene Gas. a. With the earthy principles forming the Alkalis 1*0 Chap. I. Concerning Fixed Alkalis 121 Art. I. Concerning the Vegetable Alkali, or Pot-afh ia» Art. II. Concerning the Mineral Alkali, or Soda 12 j Chap. II. Concerning Ammoniack, or the Volatile Alkali 1x7 SECTION IX. Concerning the Combination of Oxigene with certain Bafes forming Acids tj» Chap. I. Concerning the carbonick Acid 133 Art. I. Carbonate of Pot-alh 13 S Art. II. Carbonate of Soda 139 Art. III. Carbonate of Ammoniack ibid Chap. II. Concerning the Sulphurick Acid 14* Art. I. Sulphate of Pot-afh 144 Art. II. Sulphate of Soda ibid Art. III. Sulphate of Ammoniack . 145 Chap. III. Concerning the Nitrick Acid 14$ Art. I. Nitrate of Pot-alh x$z -Art. ii. Nitrate of Soda xss Art. III. Nitrate of Ammoniack 156 Chap. IV. Concerning the Muriatick Acid ibid Art. I. Muriate of Pot-afh i6» Art. II. Muriate of Soda ibid Art. III. Muriate of Arwmoniack 165 Chap. V. Concerning the Nitro-muriatick Acid - 167 Chap* VI- Concernipg the Acid of Borax 169 Art. I. Berate of Pot-afh 171 - - Art, II. Borate of Soda ibid Art. III. Bo/ate of Ammoniack ifi CONTENTS. vii PART SECOND. CONCERNING LITHOLOGY J OR AN ACCOUNT OF STONY SUBSTANCES. Page Introduction 175 Lime 178 Barytes, or Ponderous Earth 179 Magnefia, or Magnefian Earth 180 Alumine, or pyre clay ibid Sikx, or Quartzofe Earth, Verifiable Earth, &c 1* 1 CLASS I. Concerning the Combination of Earths with Acids 1S3 genus 1. Earthy Salts with Balis of Lime ibid Sped. Carbonate of Lime, or Calcareous Stone ibid Cryftallized Calcareous Stones *&5 Calcareous Stones which are not cryftallized i8« The Analyfis and Ufes of Calcareous Stone 18 J Spec. II. Sulphate of Lime, Gypfum, Selenite, Platter Stone 191 Spec. III. FluateofLime, Vitreous Spar, Fufible or Phofphorick Spar, Fluor Spar ^ 194 Spec. IV. Nitrate of Lime, Calcareous Nitre 196 Spec. V. Muriate of Lime, Calcareous Marine Salt 197 Spec. VI. Phofphate of Lime, Calcareous Phofphorick Salt 19* GENUS 11. Earthy Salts with Bafe of Barytes. 198 Spec. I. Sulphate of Barytes, Ponderous Spar ibid Spec. II. Carbonate of Barytes acm Spec. HI. Nitrate of Barytes «wj Spec. IV. Muriate of Barytes «ad GENUS III. Earthy Salts with Bafis of Magneto aoi Spec. I. Sulphate of Magnefia, Epfom Salt *id Spec. II. Nitrate of Magnefia J» 245 Spec. VUI. Silex, Alumine, Barytes, and Magnefia >oi« b x CONTENTS. CLASS III. Page Concernin g the mixtures of ftones among each other. Stony Mix- tures. Rocks. 347 genus r. Rocks formed by the mixtures of Calcareous ftones with other fpecies ibid Spec. I. Carbonate of Lime, and Sulphate of Barytes ibid Spec. II. Carbonate of Lime and Mica ibid Spec. III. Mixtures of Calcareous and Magnefian ftones 248 Spec. IV. Calcareous Stones, and Fragments of Quartz ibid GENUS 11. Compound ftones formed by the Mixture of Barytick ftones with other ftones ibid Spec. I. Ponderous Spar mixed with a fmall quantity of Calcareous Spar . ibid Spec. II. Ponderous fpar and ferpentine 249 Spec. III. Ponderous fpar and Fluor fpar ibid Spec. IV. Ponderous fpar and indurated clay ibid Spec. V. Ponderous fpar and quartz ibid Spec. VI. Ponderous fpar and lava ibid GENUS in. • Rocks or ftones formed by the mixture of magnefian ftones with other kinds 250 Spec. I. Magnefian ftones mixed together ibid Spec. II. Magnefian ftones and calcareous ftones ibid Spec. Ill- Magnefian ftones and aluminous ftones ibid Spec. IV. Magnefian ftones and filiceous ftones ibid GENUS iv. Rocks or Stones formed by the mixtures of aluminous ftones with other fpecies 251 Spec. I. Schiftus and Mica ibid Spec. II. Schiftus and Garnet ibid Spec. II f. Schiftus, Mica and Quartz mixed in fmall fragments ibid Spec. IV. Schiftus and Schorl 252 Spec. V. Clay and Quartz ibid GENUS v. Compound Stones formed by the Mixture and of Re-TJnioi of Quartzofe ftones with each other 4 253 Spec. I. Quartz and Schorl ibid Spec. II. Quartz and Feld Spar ibid Spec. III. Grit-ftone and Garnet ibid CONTENTS. XI Page Spec IV. Quartz, Feld Spar, and Schorl 254 Spec. V. Fragments of Quartz united by a Siliceous Cement ibul Spec. VI. Jafper and Feld Spar ibid Spec. VII. Jafper and Garnet 255 Spec. VIII. Jafper and Calcedony ibid Spec. IX. Jafper and Quartz 256 Spec. X. Jafper, Quartz, and Feld Spar ibid Spec. XI. Schorl, Garnet, and Tourmaline ibid genus VI. Super-compound ftones, or fuch as refult from the Mixture and Re union of feveral different Genera ibid Spec. I. Petrofilex, Alumine, and Calcareous Spar ibid Spec. II. Clay, Steatites, and Calcareous Spar 257 Spec. III. Clay, Zeolite, Schorl, and Calcareous Spar ibid Spec. ^V. Clay, ferpentine and calcareous fpar ibid Spec. V. Serpentine, Mica, and Calcareous Spar ibid Spec. VI. Serpentine, Schorl, and Calcareous Stone ibid Spec. VII. Steatites, Mica, and Garnets ibid Spec. VIII. Steatites, Mica, and Schorl ibid Spec. IX. Garnets, Quartz, Mica, and Serpentine ibid Spec. X. Feld Spar, Quartz, Mica, Steatites 258 Spec. XI. Quartz, Mica, and Clay ibid Spec. XII. Quartz, Clay and Steatites ibid Concerning the Diamond ibid General Views refpefting the Decoinpofition and Changes to which the Stony part of our Globe has been fubjec~ted 261 PART THIRD. CONCERNING METALLICR SUBSTANCES. Introduction 371 Chap. I. Concerning Arfenick 28a Chap. II. Concerning Cobalt 288 Chap. III. Concerning Nickel 291 Chap. IV. Concerning Bifmuth 29a Chap. V. Concerning Antimony 295 Chap. VI. Concerning Zinc 305 Chap. VII. Concerning Manganefe 31© Chap. VIII. Concerning Lead 316' Chap. IX. Concerning Tin 324 Chap. X. Concerning Iron 231 Art. I. Concerning Iron Ores which are attracted by the Magnet ^32 Ait. II. Concerning Sulphureous Iron Ores, or the Sulphures of Iron 33S xii CONTENTS. Page Art. III. Concerning the Spathofe Iron Ores, or Carbonates of Iron 337 Art. IV. Concerning the Bog Ores of Iron, or Argillaceous Iron Ores 33* Art. V. Concerning native Pruffian Blue, or the Prufliate of iron 339 Art. VI. Concerning Plumbago, or the Carbure of iion ibid Chap. XI. Concerning Copper 35* Chap. XII. Concerning Mercury 368 Chap. XIII. Concerning Silver 378 Chap. XIV. Concerning Gold 384 Chap. XV. Concerning Platina 393 Chap. XVI. Concerning Tungften and Wolfram 39.8 Art. I. Concerning Tungften ibid Art. II. Concerning Wolfram 40* Chap. XVII. Concerning Molybdena 404 PART FOURTH. CONCERNING VEGETABLE SUBSTANCES. Introduction 409 SECTION I, Concerning the Structure of Vegetables 413 Art. I. Concerning the Batk ibid Art. II. Concerning the Ligneous Texture 415 Art. III. Concerning the VefTds 416 Art. IV. Concerning the Glands 417 SECTION II. Concerning the Nutritive Principles of Vegetables ibid Ait. I. Concerning Water, as a Nutritive Principle of Plants 418 Art. II. Concerning Earth and its influence in vegetation 420 Art. III. Concerning Nitrogenous Gas, as a Nutritive Prinicple of 'Plants • 422 Art. IV. Concerning the Carbonick Acid, as a Nutritive Principle of Vegetables 423 Art. V. Concerning Light, and its influence on Vegetation ibid SECTION III. 425 ibid Concerning the Refults of Nutrition, or the Vegetable Principles Art. I. Concerning Mucilage Art. II. Concerning Oils A%-< Divihon I. Concerning Fixed Oils 428 Divifion II. Concerning Volatile Oils A?l4 Concerning Camphor Ai% Art. Ill- Concerning Refins 44j CONTENTS. xiii Page 444 Art. IV. i'onceming Balfams Art. V. Concerning Gum Refins Concerning Caoutchouc, or Eiaftick Gum 44« Concerning Varnilh 45I Art. VI. Concerning the Fecula of Veger Mes 453 Art. VII. Concerning the Vegetable Gluten 457 Art. VIII. Concerning Sugar 45- Art. IX. Concerning the Vegetable Acids 464 Art. X. Concerning Alkalis 473 Art. XI. Concerning the Colouring Principles 475 Art. XII. Concerning, the Polien, or Fecundating Powder of the Stamina of Vegetables 4g4 Concerning Wax 4g^ Art. XIII. Concerning Honey 4g6 Art. XIV. Concerning the Ligneous Part of Vegetables 487 Art. XV. Concerning other Fixed Principles of the Vegetable Kingdom 4gg Art. XVI. Of the Common Juices extracted by incifion or ex- preflion 490 Concerning the Juices extracted by incifion 491 Concerning Vegetable Juices extracted by Preflure 494 9 SECTION IV. Concerning fuch Principles as efcape from Vegetables by Tranfpi- ration 49J Art. I. Concerning Oxigenous Gas, afforded by Vegetables ibid Art. II. Concerning the Water afforded by Vegetables 497 Art. III. Concerning the Aroma, or Spiritus Rector ibid SECTION V. Concerning the alterations to which Vegetables are fubject after they are deprived of life jQO Chap. I. Concerning the action of Heat upon Vegetable Subftances ibid Chap. II. Concerning the action of Water fingly applied to Veget- able Subftances ^04 Concerning Fit-coal j07 Concerning Volcanos jIa Chap. III. Concerning the decoinpofition of vegetables in the bow- els of the earth ,j7 Chap. IV. Concerning the action of air and heat upon vegetables 518 Chap. V. Concerning the action of air and water, which determine a commencement of fermentation that feparates the vegeta- able juices from the ligneous part jXn Chap. VI. Concerning the action of air, of heat, and of water upon vegetables _ S2i Art. I. Concerning the Spirituous Fermentation and its products 52a Concerning Tartar j33 Art. II. Concerning the Acid Fermentation SS5 Art. HI. Concerning the Putrid Fermentation -^j xiv CONTENTS. PART FIFTH. CONCERNING ANIMAL SUBSTANCES. Page Introduction 540 Chap. I. Concerning Digeftion 543 Chap. II. Concerning Milk 545 Chap. III. Concerning the Blood 551 Chap. IV. Concerning Fat 554 Chap. V. Concerning the Bile 557 Chap. VI. Concerning the Soft and White Parts of Animals 560 Chap. VII. Concerning the Mufcular or Flcfhy Parts 564 Chap. VIII. Concerning Urine 566 Concerning the Calculus of the Bladder 571 Chap. IX. Concerning Phofphorus 5 74 Chap. X. Concerning certain Subftances obtained from Animals for the ufe of medicine and the arts 583 Art. I. Concerning the Products afforded by Quadrupeds 584 Art. II. Concerning certain Products afforded by Fifties 586 Art. III. Concerning certain products afforded by Birds 5^ Art. IV. Concerning certain products afforded by Infects 588 Chap. Xf. Concerning fome other Acidsextracted from the Animal Kingdom 59a Chap. XII. Concerning Putrefaction 595 Concerning Mineral Waters 6t>l NOTICE TO BOOKBINDERS. Signature 3...T follows immediately after 3...R. Advertisement of the Author. Agriculture is, no doubt, the bafis of pubiick welfare, becaufe it alone fupplies all the wants which nature has connected with our exiftence. But the arts and commerce farm the glory, the ornament, and the riches of every polifhed nation •, fmce our refinement, and mutual dependence on each other, have created a new fet of wants which require to befup- plied. The cultivation of the arts is therefore become almoft as neceffary as that of the ground ; and the true means of fecuring thefe two foundations of the reputation and profperity of a ftate, confift in encouraging the fcience of Chemiflry, which difcovers their principles. If this truth were not uniferfally acknowledg- ed, I might on the prefent occafion give an account of thefuc- cefs with which my labours have been attended in this prov- ince.* I might even call upon the pubiick voice ; and it would declare that, fince the eftablifhment of lectures on chemiflry, between three and four hundred perfons have every year derived advantage from inflructions in this fcience. It is well known that our ancient fchools of medicine and furgery, whofe fuccefs and fplendour are connected with the general intereft of this province, are more flouriihing and more numerous fince that period. And with the fame confidence I might appeal to the pubiick, that our manufactures are daily increasing in perfection j that feveral new kinds of induftry have been introduced into Languedoc ; that, in a regular fucceflion, abufes have been re- formed in the manufactories, while the proceffes of the arts have been Amplified ; that the number of coal mines actually wrought is increafed $ and that, upon my principles, and in con- fequence of my care and attention, manufactories of alum, of oil of vitriol, of copperas, of brown red, of artificiaJ pozzola.ia, of cerufe, of white lead, and others, have been cftablilbed in fever- al parts of the province. Chemiflry is therefore effentially connected with the reputa- tion and profperity of a ftate j and at this peculiar inftant, wh'n * Languedoc. 16 ADVERTISEMENT OF THE AUTHOR. the minds of men are univerfally bufied in fecuring the pubiick welfare, every citizen is accountable to his country for all the good which his peculiar fituation permits him to do. Every one ought to haften, and prefent to fociety the tribute of thofe talents which heaven has beftowed on him ; and there is no one who is not able to bring fome materials, and depofite them at the foot of the fuper'o edifice which the virtuous adminiftrators are raifingfor the welfare of the whole. It is with thefe views that I haveprcfumed to offer to my countrymen the work which I at prefent publifh j and I entreat them to exercife their feveri- ty upon the intention of the author only, but to referve all their indulgence to the work. I publifh thefe elements of Chemiflry with the greater confi- dence, becaufe I have had opportunities myfelf of obferving the numerous applications of the principles which conflitute its bafis to the phenomena of nature and art. The immenfe eflab- lifhment of chemical products which I have formed at Mont- pellier, has allowed me to purfue the developement of this doc- trine, and to obferve its agreement with all the facts which the various operations prefent to us. It is this doctrine alone which has led me to Gmplify mod of the pro'ceffes, to bring fome of them to perfection, and to rectify all my ideas. It is therefore with the moft intimate confidence that I propofe it. I find no difficulty in making a pubiick acknowledgment that I have for fome time taught a different doctrine from that which I at prefent offer. I then believed it to be true and folid ; but I did not on that account ceafe to confult nature. I have con- flantly entered into this refearch with a mind eager for improve- ment. Natural truths were capable of fixing themfelves with all their purity in my mind, becaufe I hadbanifhed prejudice ; and infenfibly I found myfelf drawn by the force of facts to the doctrine I now teach. Let other principles imprefs the fame conviction on my mind ; let the fame number of phenomena and facts exhibit themfelves in their favour ; the fame number of happy applications to the operations of nature and of art ; let them appear to my mind with all the facred characters of truth j and I will publifh them with the fame zeal ; and with the fame intereft. I condemn equally the man who, at- tached to the ancient notions, refpects them fo much as to re- ject without mature examination every thing which appears to oppofe them ; and him who embraces with enthufiafm, and al- raoft without reflection, the principles of any new doctrine. Both are worthy of compr.flion if they grow old in their preju- dice.? ; and bo:a are worthy of blame if they perpetuate t'^m. ADVERTISEMENT OF THE AUTHOR. i? I have been careful to banifh all difcuflions from my work. That fpirit of party which but too often caufes a divifion between perfons who are purfuing the fame objects, that tone of bitter- nefs which predominates in certain difputes, that want of can- dour which is infenfibly produced by the movements of felf-love, have but too long retarded the progrefs of our knowledge. The love of truth is the only paflion which a philofopher ought to indulge. The fame object, the fame interefl, tend to unite chemifls. Let the fame fpirit infpire them, and direct all their labours. Then we fhall foon behold chemiflry advancing in a rapid progrefs ; and its cultivators will be honoured with the fuffrage and the gratitude of their countrymen. I have endeavoured in this work to explain my ideas with clearnefs, precifion, and method. I know by experience that the fuccefs of any work, and its various degrees of utility, often depend on the form under which the doctrine which it contains is difplayed ; and it has accordingly been my intention to fpare no pains in exhibiting the truths which form the bafis of this Work in all the characters they are juftly entitled to. In compofing thefe elements of chemiflry, I have availed my- felf with advantage of all the facts which I have found in the works of the celebrated chemifls who adorn this age. I have even made no fcruple to follow their method in drawing up certain articles ; and have transferred into my own work, al- mofl without alteration, thofe facts which I have elfewhere found defcribed with a greater degree of precifion and perfpi- cuity than I might have been capable of bellowing on them. This proceeding, in my opinion, renders homage to authors in* flead of robbing them. If fuch a proceeding might juftify re- clamations, Meffrs. Lavoifier, De Morveau, Berthollet, De Fourcroy, Sage, Kirwan, &c. might eafily declare againft me. I was well aware that the pretention of knowing, difcuffing, and methodically diflributing the whole of our prefent fcience of chemiflry, was an enterprize beyond my ability. This fci- ence has made fo great a progrefs, and its applications are fo multiplied, that it is impoflible to attend to the whole with the fame care ; and it appears to me that the writer of an elemen- tary work ought at prefent to attend principally to the develope- ment of general principles, and content himfelf in pointing out the confequences, and their applications. In this way of pro- ceeding we fhall follow the method which has long been prac- tifed, in the ftudy of the mathemiticks; the principles of which, nearly infulated, and feparated from all application, -form the firfi ftudy cf him who means to acquire them. C ra ADVERTISEMENT OF THE AUTHOR. To obtain a thorough acquaintance with all the knowledge which has been acquired in chemiflry until our time, the chem- ical part of the Encyclopedic Methodique may be confulted. In this work the celebrated author gives the me»ft intercfting ac- count of the progrefs of the fcience. Here it is that he difcufT- es the feveral opinions with that candour and energy which be- come the man of letters, whofe mind is directed to truth only. Here it is that he has made a precious depofite of all the knowt- edge yet acquired, in order to prefent to us in the fame point of view all which has been done, and all which remains to be done : and here, in a word, it is that Mr. De Morveau has ren- dered the molt flriking homage to the truth of the- doctrine we now teach j becauie, after having combated fome of its princi- ples in the firft volume, he has had the courage to recant, the moment the facets feen in a better point of view, and repeated experiments, had fufficiently enlightened him. This great ex- ample of courage and candour is doubilefs honourable to the learned man who gives it -, but it cannot fail to add ftill more to the confidence which may be placed in the doctrme which is its object. The developement of the principles upon which the New Nomenclature is eftabhthed, may be found in the Elementary Treat-ife of Chemiflry of Mr. Lavoifier ; and I refer likewife to this excellent work for the figure and explanation of all the ap- paratus I fhall have occafion to fpeak of. I take this ftep the more earneftly, becaufe, by afibciating my own productions to thofe of this celebrated chemiii, I entertain the hope of fecuring their fuccefs, and can deliver them into the hands of the pubiick with the greater confidence. I fStcliminatp Discourse* IT appears that the ancient nations pofFefled fome no- tions of chemiflry. The art of working metals, which dates from the moft remote antiquity ; the luftre Which the Phoeni- cians gave to certain colours ; the luxury of Tyre ; the numer- ous manufactures which that opulent city included within its walls—all announce a degree of perfection in the arts, and fup- pofe a confiderable extent and variety of chemical knowledge. But the principles of this fcience were not then united into a body of doctrine ; they were concentrated in the workfhops of the manufactures, where they had their origin : and observa- tions alone, tranfmitted from one operator to another, enlighten- ed and conducted the fteps of the artifts. Such, no doubt, has been the origin of all the fciences. At firft they prefented un- connected facts ; truths were confounded with errour •, time and genius alone could clear up the confufion ; and the pro- grefs of information is always the fruit of flow and painful ex- periment. It is difficult to point out the precife epocha of the origin of chemical fcience j but we find traces of its exiftence in the moll remote ages. Agriculture, mineralogy, and all the rarts which are indebted to it for their principles, were cultivated and enlightened. We behold the original nations, immediately fucceeding the fabulous ages, furrounded by all the arts which fupplied their wants ; and we may compare chemiflry to that famous river, whofe waters fertilize the lands they inundate, but whofe fources are ftill to us unknown. Egypt, which appears to have been the nurfe of chemiflry, re- duced to principles, was not flow in turning the applications of this fcience towards a chimerical end. The firft feeds of chem- iflry were foon changed by the pafiion of making gold. In a moment all the labours of operators were directed towards al- chemy alone ; the great object of ftudy became fixed on an en- deavour to interpret fables, allufions, hieroglyphicks, &c. ; and the induftry of feveral centuries was confecrated to the enquiry after the philosopher's ftone. But though we admit that the alchemifts have retarded the progrefs of chemiflry, we are very fir from being difpofed to any outrage on the memory of thefe 20 PRELIMINARY DISCOURSE. philofophers •, we allow them the tribute of efteem to which on fo many accounts they are entitled. The purity of their fenti- ments, the fimplieity of their manners, their fubmifBon to Prov- idence, and their love for the Creator, penetrate with veneration all thofe who read their works. The profoundeft views of gtf- nius are every where feen in their writings, allied with the moil extravagant ideas. The moil fublime truths are degraded by ap* plications of the moft ridiculous nature ; and this aftonifhing contrafl of fuperflition and philofophy, of light and darknefs, compels us to admire them, even at the inftant that we cannot ■withold our cenfure. .We mult not confound the feet of al- chemifls, of whom we fhall proceed to fpeak, with that crowd of impoitors, that fordid multitude of operators at the furnace, whofe researches were directed to the difcovery of minds capa-? ble of being impofed upon, who fed the ambition of fuch weak minds by the deceitful hope of increafing their riches. This laft clafs of vile and ignorant men has never been acknowledged by the true alchemifts ; and they are no more entitled to that name, than the vender of fpecificks on the ftage to the honoura^ ble name of Phyfician. The hope of the alchemift may indeed be founded on a {len- der bafis j but the great man, the man of genius, even at the time when he is purfuing an imaginary'object, knows how to profit by the phenomena which may prefent themfelves, and de- rives from his labours many ufeful truths, which would efcape the penetration of ordinary men. Thus it is that the alchemifts have fucceffively enriched pharmacy and the arts with mofl ot their compositions. The ftrong defire of acquiring riches has in all times been a paflion fo general, that this fingle, motive has, been fufficient to lead many perfons to the cultivation of a fci- # ence which has more relation than any other to metals ; which iludies their nature more particularly, and appears to facilitate the means of compofing them. It is known that the Abdarites did not begin to confider the fciences as an occupation worthy a reafonablg man, until they had feen a celebrated philofophep enrich himfelf by (peculations of commerce : and I do not doubt but that the defire of making gold has decided the vocation of feveral chemifls. We are therefore indebted to alchemy for feveral truths, and for feveral chemical profeflprs : but this ob- ligation is fmall in comparifon to the mafs of ufeful truth which might have been afforded during trie courfe of feveral centuries ; if, inftead of endeavouring to form the metals, the operations o£ chemifls had been confined to analyfing them, Amplifying the. means of extracting them, combining them together, working * them, and multiplying and rectifying their ufes. * PRELIMINARY DISCOURSE. ti The rage for making gold was fucceeded by the fedudtive hope of prolonging life by means of chemiflry. The perfua- fuafion was eafily admitted, that a fcience which affords reme- dies for all diforders might without effort fucceed in affording a univerfal medicine. The relations which have been handed down to us of the long life of the ancients, appeared to be a natural effect of their knowledge in chemiflry. The numer- ous fables of antiquity obtained the favour of being admitted among eftablifhcd facts ; and the alchemifts, after having ex- haufled themfelves in the fearch after the philofopher's (lone, appeared to redouble their efforts to arrive at an object ftill more chimerical. At this period the elixirs of life, the arcana, the polychreft medicines, had their origin : together with all thofe monftrous preparations, of which a few have been handed do'wn even to our days. The chimera of the univerfal medicine agitated the minds of molt men in the fixteenth century ; and immortality was then promifed with the fame effrontery as a charlatan now announ- ces his remedy for every difeafe. The people are eafily feduced by thefe ridiculous promifes ; but the man of knowledge can never be led to think that chemiflry can fucceed in reverfing the general law of nature, which condemns all living beings to renovation, and a continual circulation of decompofitions and fucceflive generations. This fact gradually became an object of contempt. The enthufiaft Paracelfus, who after having flatter- ed himfelf with immortality, died at the age of forty-eight, at an inn at Saltfhurg, completed its difgrace.—From that mo- ment the fcattered remains of this feet united themfelves never more to appear again in pubiick. The light, which be- gan to fhine forth on all fides, rendered it neceffary that they fhould have recourfe to fecrecy and obfeurity j and thus at length chemiflry became purified. .;, James Barner, Bohnius, Tachenius, Kunckel,*Boyle, Crol-r lius, Glafer, Glauber, Schroder, &c. appeared* op, the ruins of thefe two fects, to examine this indigefted aggregate, and fep- arate from the confufed mafs of phenomena, of truth and of errour, every thing which could tend to enlighten the fcience. The feet of the adepts, urged on by the madnefs of immortali- ty, had difcovered many remedies ■, and pharmacy and* the arts then became enriched with formulae and compofrtions, Whofe operations required only to be rectified, and their applications better eftimated. . / Nearly at the fame time appeared the celebrated Becher. He withdrew chemiflry from the too narrow limits of phar- macy. He Ihewed its connexion with all the phenomena of 22 PRELIMINARY DISCOURSE. nature ; and the theory of the formation of metals, the pheno- mena of fermentation, the laws of putrefaction, were all com- prehended and developed by this foperiour genius. Chemiflry was then directed to its true object: and St.ial, who fucceed- ed Becher, reduced to certain general principles all the facts with which his predeceflbr had enriched the fcience. He fpoke a language lefs enigmatical ; he claffcd all the facts with order and method ; and purged the fcience of that alchemiek infection, to which Becher himfelf was too much attached. But if we confuler how great are the claims of Siahl, and how few the additions which have been made to his doctrine until the middle of this century, we cannot but be aftonifhed at the fmall progrefs of the fcience. When we confult the labours of the cheuifts who have appeared fince the time of Stahl, we fee moft of them chained down to the fteps of this great mas, blindly fubferibing to all his ideas ; and the labour of think- ing appeared no longer to exifl among them. Whenever a well made experiment threw a gleam of light unfavourable to ills doctrine, we fee thera torment themfelves in a ridiculou# manner to form a delufiVe interpretation. Thus it was that the increafe of weight which metals acquire by calcination^ though, little favourable to the idea of the fubtraction of a prin- ciple without any other addition, was neverthelefs incapable of injuring this doctrine. The almoft religious opinion which enflaved all the chemifls to Stahl, has no doubt been pernicious to the progrefs of cherfi*» tilry. But the ftrong defire of reducing every thing to firlt principles, and of eflablifhing a theory upon incomplete experi- ments or facts imperfectly feen, did not admit of the fmallefl obftacles. From the moment that analyfis had (hewn fome of the principles of bodies, the chemift thought himfelf in pofie£ fion of the- firft agents of nature. He confidered himfelf as authorized to regard thofe bodies as elements which appeared no longer fufceptiblc of being decompofed. The acids and the al- kalis performed the principal part in natural operations : and if appeared'to be a truth buried in oblivion, that the term where the artilt flops is not the point at which the Creator has limited his power : and that the laft refult of analyfis does indeed mark the limits of art but doe3 not fix thofe of nature. We might hkewife reproach certain chemifls for having too long neglect- ed the operations or the living fyflems. They confined them- felves in 'their laboratories, fludied no bodies but in their life- lefs ftate, ."i. 1 were incapable of acquiring any knowledge but fuch as wa* very incomplete .• for he who in Ms researches, has no ether ohj'cl in vie; tir.iu that of afcertaiaing the principle* PRELIMINARY DISCOURSE. *3 •f a subftance, acts like a phyfician who mould fuppofe he had acquired a complete notion of the human body by confining his ftudies to the dead carcafs. But we muft likewife obferve, that in order to form a proper notion of the phenomena of liv- ing bodies, it is neceflary to pofiefs the means of confining the gafeous principles which efcape from bodies ; and of analyfmg thefe volatile and invrftble fubftances which combine together^ Now this work, was impoflable at that time j and we ought to beware of imputing to men thofe errours which arifc from the ftate of the times in which they lived. It may perhaps be demanded on this occafion, why cberaiftry was fooner known, and more generally culti- vated, La Germany and in the North than in our kingdom. I think that many reafons may be given for this. In the firft place the fcholars of Stahl and of Becher nrnft have been more numerous, and confequently their instruction far- ther extended. Secondly the working of mines, having become a refource necefiary to the governments of the north, has been fingularly encouraged ; and that chemiflry, which enlightens mineralogy, muft neceflarily have participated in its encourage- ments.* The ftudy of chemiflry did not begin to be cultivated to ad- vantage in France until the end of the laft century. The firft wars of Louis XIV. fo proper to develope the talents of the art- ift, the hiftorian and the military man, appeared tittle favoura- ble to the peaceable ftudy of nature. The naturahft who in his refearches, fees union and harmony around him,, cannot be an indifferent fpecfator of the continual fcenesof diforder and de- ftruction; and his genius is crufhed in the midft of troubles and agitations. The mind of the great* Colbert, deeply pene- trated with thefe truths, quickly endeavoured to temper the fire of difcord, by turning the minds of men towards the only objects * Sinee the French government has facilitated' the ftudy ,«»£ mineralogy by the moft fupcrb eftablifhments, we have beheld the tafte for cjjemiftry revive; the arts which have the workiDg of metals for their object have been rendered more perfect, and the mines which have heen wrought are more numerous. Mr. Sage has been more particularly aifiduous and zealous to turn the fa- vour of government towards this objed. I have been a witnefs to the labo- rious attention of this chemift to effect this revolution. I have beheld the perfonal facrifices he made to bring it forward. I have applauded his zeal his motives and his talents. The fame* fentiment9 flill occupy my mind- and though I teach a doctrine at prefenl; which is different from his, this cir-' cumltance arifes from the impoflibility of commanding opinion*. The phi- losopher who is truly worthy of this name, is capable of diftinguifhing the friend of his Ivart from the flavc of his fyftem ; and in a word, every one ought to write according to his conviction; the moft facred axi'jro of tJ»e Sciences being _" Amicus Plato,fed magi* arnica Veritas." 24 PRELIMINARY DISCOURSE. which could fecure the peace and profperity of the ftate. H« exerted himfelf to render trade flourifhing ; he eftablifhed manufactories ; learned men were invited from all parts, en- couraged and united together, to promote his vaft projects'. Then it was that the ardour of enquiry replaced for a time the fury of conquefl ; and France very foon flood in competition with all nations for the rapid progrefs of the fciences, and the perfection of the arts. Lemery, Homberg, and GeofFroy arofe nearly at the fame time : and other nations were no longer en- titled to reproaoh us for the want of chemifls. From that mo* ment the exiftence of the arts appeared to be well allured. All the fciences which afford their firft principles, were cultivated with the greateft fuccefs: and it will fcarcely be credited that, in the fpace of a few years, the arts were drawn from a ftate of non-entity ; and carried to fuch a degree of perfection, that France, which had before received every thing from foreign countries, became in pofleflion of the glory of fupplying its neighbours with models and with merchandizes. Chemiflry and natural hiflory, however, at the beginning of this century, were cultivated only by a very fmall number of perfons ; and it was then thought that the ftudy of thefe fcien- ces ought to be confined to the academies. But two men, whofe names will be ever famous, have rendered the tafle gen- eral under the reign of Louis XV. The one poffefTed that no- ble fpirit which is a ftranger to the riower of prejudice, that indefatigable ardour which fo eafily overcomes every obflacle, that opennefs of character which infpires confidence, and trans- fufcd into the minds of his pupils that enthufiafm of which he himfelf felt the force. While Rouelle enlightened the fcience of chemiflry, Buffort prepared a revolution flill more aflonifhing in natural hiflory.. The naturalifls of the North had fucceed- ed in caufing their productions to be read by a fmall number of the learned ; but. the works of the French naturalifl were foon, like thofe of nature, in the hands of the whole world. He pofieffed the art of diffufing through his writings that lively intereft, that enchanting colouring, and that delicate and vigo- rous touch, which influence, attach, and fubdue the mind. The profundity of his reafoning is every where united to all that agreeable illufion which the moft brilliant imagination can fur- nifh. The facred fire of genius animates all his productions; his fyftems conftantly exhibit the moft fublime profpects in their totality, and the moft perfect correfpondence in their minute parts: and, even when he exhibits mere hypothefes, we are in- clined to perfuade ourfelves .that they are eftablifhed truths. We become like the artift who, after having admired a beauti- PRELIMINARY DISCOURSE. 2S ful flatuc, ufed his efforts to perfuade himfelf that it refpired, and removed every thing which could diffipate his iilufion. We hike up his work with a plcafure refembling that of the man who turns again to fleep, in hopes of prolonging the deception of an agreeable dream. Thefe two celebrated men, by diffufing the tafle for chemif- try and natural hiflory, by making iheiv relations and ufes bet- ter known, conciliated the favour of government towards them ; and from that moment everyone intereflcd himfelf in the prog- refs of both fciences. Thofe perfons who were beft quali- fied in the kingdom, haftened to promote the revolution which was preparing. The fciences foon inferibed in their lift of cultivators the beloved and refpected names of La Roche- foucalt, Ayen, Chaulnes, Lauraguaio, Malefherve, &c. ; and thefe men, diftinguifhed by their birth, were honoured with a new fpecies of glory, which is independent of chance or pre- judice. They enriched chemiflry with their difcoveries, and af- fociated their names with all the other literati who purfued the fame career. They revived in the mind of the chemifl that paf- fion for glory, and that ardour for the pubiick good, which con- tinually excite new efforts. The man of ambition and intrigue np longer endeavoured to depr.efs the modefl and timid man of genius. The credit of men. in place ferved as a defence and fupport againft calumny and perfecution. Recompenfes were affigned to merit. Learned men were defpatched into all parts of the world, to ftudy the arts, and collect their productions. Men of the firft merit were invited to inftruct us with regard to our own proper riches ; and eftablifhments of chemiflry, which were made in the principal towns of the kingdom, dif- fufed the tafte for this fcience, andj fixed among us thofe arts which we might in vain have attempted to naturalize, if a firm bafis had not been firft laid. The profeffors eftablifhed in the capital and in the provinces, appeared to be placed between the academies and the people, to prepare the latter for thofe truths which flow from fuch refpectable affociations. We may con- fider them as a medium which refracts and modifies the rays of light that ifTue from thofe various luminous centres' ; and directs them towards the manufactories, to enlighten and im- prove their practice. Without thefe favours, without this con- sideration and thefe recompenfes, could it have been expected that the moft unaffuming among philofophers would have exert- ed himfelf to promote the reputation of a people to whom he was unknown ? Could a man fo fituated reasonably hope to fuccei'd in curving a difcovery into effect? lb it probable that he fhould have poffcffed a fuflicieut f Jitune to work in the large D* *6 PRELIMINARY DISCOURSE. way, and by this means alone to overcome the numbcrlefs pre- judices which banifh men of fcience from manufactories ? The contemplative fciences demand of the fovereign repofe arid lib- erty only : but experimental fciences demand more, for they require affiftance and encouragement. What indeed could be hoped in thofe barbarous ages wherein the chemifl fcarce- ly durfl avow the nature of the occupation which in fecret conftituted his greatefl pleafure. The title of chemifl v.i; almoft a reproach ; and the prejudice which confounded the profeffors of this fcience with fuch wretched projectors as are entitled only to pity, has probably kept back the revival of the arts for feveral centuries ; for chemiflry alone can afford them a proper bafis. If the princes of paft times had been friends of the arts and jealous to acquire a pure and durable reputation ; if they had been careful to honour the learned, to collefl their valuable labours, and to tranfmit to us without alteration the precious annals of human genius •, we fhould have been difpen- fed from labouring among the rubbifh of early times, to con- fult a few of thofe remains which have efcaped the general wreck ; and we fhould have been fpared the regret of allowing, after many ufelefs refearches, that the mailer-pieces of anti- quity which remain anfwer fcarcely any other purpofe than to give us an idea of that fuperiority to which the earlier nations had arrived. Time, the fword, fire, and prejudice have devour- ed all : and our refearches ferve only to add to our regret for the loffes which the world has fuftained> The fcience of chemiflry poffeffes the glory, in our days, not only of having obtained the protection of government, but it may likewife boaft of another equally elevated. This fcience has fixed the attention, and formed the occupation, of various men, in whom the habit of a profound ftudy of the accurate fciences had produced a neceflity. of admitting nothing but what is proved, and of attaching themfelves only to fuch branches of knowledge as are fufceptible of ftrict proofs. Meffrs. De la Grange, Condbrcet, Vander, Monde, Mong-j, De la Place, Meufnier, Coufin, the moft celebrated mathematicians of Eu- rope, are all interefted in the progrefs of this fcience, and moll of them daily add to its progrefs by their difcoveries. So great a mafs of inftruction, and fuch ample encourage- ment, coul: not but effect a revolution in the fcience itfelf j and we are indebted to the combined efforts of all thefe learned men for the difcovcry of feveral metals, the creation of various ufeful arts, the knowledge of a number of advantageous procef- fes, the working of feveral mines, the analyfis of the gale.", the decompofition of water, the theory of heat, the doctrine of com- buflion j and a mafs of knowledge fo abiblute and fo extended, PRELIMINARY DISCOURSE. 27 reflecting all the phenomena of art and of nature, that in a very fliort time chemiflry has become a fcience entirely new. We might now fay with much more truth what the celebrated Bacon affirmed of the chemiflry of his time ; " A new philofophy," fays he, " has iffued from the furnaces of the chemifls, which has confounded all the reafonings of the ancients." But while difcoveries became infinitely multiplied in chem- iflry, the peceffity of remedying the confufion which had fo •long prevailed, was foon feen, and indicated the want of a re- form in the language of this fcience. There is fo intimate a re- lation between words and facts, that the revolution which takes place in fhe'principles of a fcience ought to be attended with a limilar revolution in its language : and it is no more poflible to prcferve a vicious nomenclature with a fcience which becomes enlightened, extended, and fimplified, than to polifh, civilize, and inftruct uninformed man without making any change in hi§ natural language. Every chemift who wrote on anyfubject was ftruck with the inaccuracy of the words in common ufe, and confidered himfelf as authorized to introduce fome change ; infomuc'h that the chemical language became infenfibly longer, more confufed, and more unpleafant. Thus carbonick acid has been known during the courfe of a "few years, under the names of Fixed Air, Aerial Acid, Mephitick Acid, Cretaceous Acid, &c. ; and our poflerity may hereafter difpure whether thefe va- rious denominations were not applied to different fubftances. The time was therefore come, in which it was ncceffarv to re- form.the language of chemiflry ; the imperfections of the an- cient nomenclature, and the difecvery of many new fubftances, rendered this revolution indifpenfable. But it was neceffarv to defend this revolution from the caprice and fancy of a few- individuals ; it was neceffary to eftablifh this new language up- on invariable principles : and the only means of infuring this* jiurpofe was doubtlefs that of erecting a tribunal in which chemr ills of acknowledged merit fhould difcufs the words received, without prejudice and without intercft ; in which the princi- ples of a new nomenclature might be eftablifhed and purified by the fevereft logick ; and in which the language fhould be fo well identified with the fcience, the word fo well applied to the fact, that the knowledge of the one fhould lead to the knowledge of the other. This was executed in 178:} by Meffrs. De Morveau, Lavoifier, Bertholler, and Dc Fourcroy. In order to eftablifh a fyftem of nomenclature, bodies muft be confidered in two different points of viev, and diftributed into two claffes ; namely, the clafs of firvple fubftances reputed *o be elementary, and the clafs of combined fubltances. 28 PRELIMINARY DISCOURSE. v i. The rnjft natnr.-1-and fuitable denominations which can be affigned to fimple fubftances, muft be deduced from a princi- ple and characteriftick property of the fubftance intended to be expreffed. They may hkewiic be diftinguiflied by words which do not prefent any precife idea to the mind. Moft of the re- ceived names are eftablifhed on this laft principle, fuch as the names of Sulphur, Phofphorss, which do not convey any fi uni- fication in our language, and produce in our minds determinate ideas only, becaufe ufage has applied them to known fubftances. Thefe words, rendered facred by ufe, ought to be preferve I in a new nomenclature : and no change ought to be made, except- ing when it is propofed to rectify vicious denominations. In this cafe the authors of the New Nomenclature have thought it proper to deduce the denomination from the >principal char- acteriftick property of the fubftance. Thus, pure air might have been called Vital Air, Fire Air, or Oxigenous Gas ; be- caufe it is the bafis of acids, and the aliment of refpiration and combuftion. But it appears to me that this principle has been in a fmall degree departed from when the name of Azotick Gas was given to the atmofpherical mephitis—i. Becaufe none or the known gafeous fubftances excepting vital air being propes for refpiration, the word Azote agrees with every one of them except one ; and confequently this denomination is not found- ed upo:i an exclufive property, diftinctive and characteriftick of the gas itfelf. 2. This denomination being once introduced, the nitrick acid ought to have been called Azotick Acid, and its combinations Azotates ; becaufe the acids are propoied to bs denoted by the name which belongs to their radical. 3. It the denomination of Azotick Gas does not agree with this aeri- form fubftance, the name of Azote agrees ILiil lefs with the con- crete and fixed fubftance ; for in this ftate all the gafes are ef- fentially azotes. It appears to me therefore that the denomina- tion of Azotick Gas is not eftablifhed according to the principles which have been adopted ; and that the names given to the fev- eral fubftances of which this gas conftitutes one of the elements, are equally removed from the principles of-the Nomenclature. In order to correct the Nomenclature on this head, nothing more is neceilary than to fubftitute to this word a denomination which is derived from the general fyftem made ufe of: and I have prefumed to propofe that of Nitrogene Gas. In the firft place, it is deduced from the exclufive and characteriftick prop- erty of this g.ir,} which forms the radical of the nitrick acid. By „ this means w _ lhall preferve to the combinations of this fubftance- the received denomination.;, fuch as thofe of the Nitrick Acid, Nitrates, Nitrites, &x. In this ;.f-'r'.er the word, which is af- PRELIMINARY DISCOURSE. 29 forded by the principles, adopted by the celebrated authors of the nomenclative, caufes every thing to return into thu order propofed to be eftablifhed. 2. The method made ufe of to afcertain the denominations fuitable to compound fubftances appears to me to be fimple and accurate. It has been thought that the language of this part of fcience ought to prefent the analyfes ; that the words fhould be only the exprefiion of facts ; and that confequently the denomination applied by a chemifl tp any fubftance which has been analyfed, ought to render him acquainted with its con- ftituent parts. By following this method, the Nomenclature is as it were united, and identified with the fcience ; and facts and words agree together. Two things are therefore united,.which until this time appeared to have no mutual relation, the word, and the fubftance which it reprefented ; and by this means the ftudy of chemiflry is fimplified. But when we apply thefe incon- teftible principles to the various objects of chemiltry we ought to follow the analyfis ftep by ftep, and upon this ground alone eftablifh genera! and individual denominations. We ought to ohferve, that it is from this analytical method that the various denominations have been affigned, and that the methodical dis- tributions of natural hiftcry have been at all times made. If man were to open his eyes for the firft time upon the various beings which people or compofe this globe, he would eftablifh their relation upon the comparison of their moft evident properties, and no doubt would found his firft divifions upon the moft fen- fible differences. The various modes of exiftence, or their fev- eral dt-grees of confiftence, would form his firft divifion ; and he would arrange them under the heads of folid, liquid, or aeriform bodice. A more profound examination, and a more connected analyfis of the individuals, would foon convince him that the fubftances which certain general relations had in- duced him to unite in the fame clafs, uader a generick denomi- nation, differed very effentially among each other, and that thefe differences neceffarily required fubdivifion. Hence he would divide his folid bodies into ftones, metals, vegetable fub- ftances, animal fubftances, &c. his liquids would be divided into \v;uer, vit.u air, in flammable air, mephitick air, &c. When he proceeded to cany his refearches on the nature of thefe fub- ftances iiill farther, he would perceive that moft of the individ- uals were formed by the union of fimple principles ; and here it is that his applications of the fyftem to be followed, in aflign- ;ng a fuitable denomination to each fubftance, would begin. To anlwer this purpose, the authors of the New Nomenclature have endeavoured to exhibit denominations which may point 3° PRELIMINARY DISCOURSE. out the conftituent principles. This admirable p'an has been carried into execution as far as relates to fubftances which are not very complicated, fuch as the combinations of the principles with each other; the acids, earths, metals, alkalis, &c. And this part of the Nomenclature appears to me to leave nothing more to be defired. The explanation may be {cen in the work publifhed on this fubject by the authors, and in the Elementary Treadle of Chemiflry of Mr. Lavoifier. I fhall therefore do nothing more in this place than prefent a fketch of the method I have followed ; taking for example.the combinations of acids, which form the moft numerous clafs of compounds. The firft ftep con filled in.comprehending under a general de- nomination the combination of an acid with any given bafis-; and in order to obferve a more exact arrangement, and at the fame time to afhft the memory, one common termination ha.; been given to all words which denote the combination ot an acid. Hence the words Sulphates, Nitrates, Muriates, are ufed, to denote combinations of the fulphurick, nitrick, and muriatick acids. The kind of combination is denoted by adding to the generick word the name of the body which is combined with the acid ; thus, the fulphate of pot-afh exprefies the combination of the fulphurick acid with pot-afh. The modifications of thefe fame acids, dependent on the proportions of their conftituent principles, form falts different from thofe we have juft fpoken of; and the authors of the New Nomenclature have expreffed the modifications of the acids by the termination of the generick word. The difference in the acids arifes almoft always from the greater or lefs abundance of oxigene. In the firft cafe, the acid affumes the epithet of Oxi- genated ; hence the oxigenated muriatick acid, the oxigenated fulphurick acid, &c. In the fecond cafe, the termination of the word which denotes the acid, ends in otts ,• hence the fulphur- ous acid, the nitrous acid, &c. The combinations of thefe laft form fulphites, nitrites, &c ; the combinations of the former compofe oxigenated muriates, oxigenated fulphates, &c. The combinations of the various bodies which compofe this globe are not all as fimple as thofe here mentioned, a»d it may be immediately perceived how long and troublefome the denom- inations would be, if attempts were made to beftow a fingle denomination which fhould denote the conftituent principles of a body formed by the union of five or fix principles. In this cafe, the preference has been given to the received appellation, and no other changes have been admitted but fuch as were ne- ceffary in order to fubftitute proper appellations, inflead of thofe which afforded notions contrary to the nature of the objects they were applied to. PRELIMINARY DISCOURSE'* 2* I have adopted this Nomenclature in my lecture?, and in my writings •> I have not failed to perceive how very advantageous- it is to the teacher, how much it relieves the memory, how greatly it tends to produce a tafle for chemiflry, and with what facility and precifion the ideas and principles concerning the na- ture of bodies fix themfelves in the minds of the auditors. But I have been careful to iufertthe technical terms ufed in the arts, or received in fociety, together with thefe new denominations. I am of opinion that, as it is impoflible to change the language of the people, it is neceffary to defeend to them, and by that means render them partakers of our difcoveries. We fee, for example, tfyat the artift is acquainted with the fulphurick acid by no other name than that of Oil of Vitriol, though the name of the Vitriolick Acid has been the language of chemifls for a century paft. We cannot hope to be more happy in this refpect than our predeceffors ; and, fo far from feparating ourfelves from the artift by a peculiar language, it is proper that we mould multiply the occafions of bringing us together; fo far from at- tempting to en Have him by our language, we ought rather to infpire his confidence by learning hiaterms. Let us prove to the artift that our relations with him are more extended than he imagines ; and let us by this intimacy eftablifh mutual corref- pondence, and a concurrence of information, which cannot but redound to the advantage of the arts and of chemiflry. After having explained the principal objections which have retarded the improvement of chemiflry, and the caufes which in our time have accelerated its progrefs, we fhall endeavour to point out the principal applications of this fcience ; in which attempt, we think, we fhall fucceed belt by cafting a general retrofpect over thofe arts and fciences which receive certain principles from it. Moft of the arts are indebted to accident for trieir difcoverv. They are in general neither the fruit of refearch, nor the refult of combination, but all of them have a more or lefs evident relation to chemiflry. This fcience therefore is capable of clear- ing up their firft principles, reforming their abufes, Amplifying their operations, and accelerating their progrefs. Chemiflry bears the fame relation to moft of the arts, as the mathematick have to the feveral parts of fcience which depend on their principles. It is poffible, no doubt, that works of me- chanifm may be executed by one who is no mathematician ;, and fo likewife it is poffible to die a beautiful fcarlet without being a chemift : but the operations of the mechanick, aad of the dyer, are not the lefs founded upon invariable principles, the knowledge of which would be of infinite utility to the artift. 32 PRELIMINARY DISCOURSE. We continually hear in manufactories of the caprices and un- certainty of operations ; but it appears to me that this vague expreffion owes its birth to the ignorance of the workmen with regard to the true principles of their art. For nature itfclf does not act with determination and difcernment, but obeys invaria- ble laws; and the inanimate fubftance which we make ufe of in our manufactures, exhibits neceffary effects, in which the will has no part, and confequently in which caprices cannot take place. Render yourfelves better acquainted with the ma- terials you work upon, we might fay to the artifts; ftudy more intimately the principles of your art ; and you will be able to forefee, to predict, and to calculate every effect. It is your ig- norance alone which renders your operations a continual feries of trials, and a difcouraging alternative of fuccefs and difap- pointment. The pubiick, which continually exclaims that experience is better than fcience, encourages and fupports this ignorance on the part of the artift; and it will not be remote from our ob- ject to attempt to afcertain the true value of thefe terms. It is very true, for example, that a man who has had a very long experience may perform operations with exadtnefs ; but he will always be confined to the mere manipulation. I would com- pare fuch a man to a blind perfon who is acquainted with the road, and can pafs along it with eafe, and perhaps even with the confidence and affurance of a man who fees perfectly well; but is at the fame time incapable of avoiding accidental obflacles, incapable of fhortening his way or taking the moft direct courfe, and incapable of laying down any rules which he can commu- nicate to others. This is the ftate of the artift of mere experi- ence ; however long the duration of his practice may have been, as the fimple performer of operations. It may perhaps be replied, that artifts have made very impor- tant difcoveries in confequence of afliduous labour. This is in- deed true, but the examples are very fcarce ; and we have no right to conclude, becaufe we have feen men of genius without any mathematical theory execute wonderful works of mechan- ifm, that the mathematicks are-not the bafis, or that any one has a right to expect to become a great mechanick without a pro- found ftudy of mathematical principles. It appears to be generally admitted at prefent, that chemiflry is the bafis of the arts : but the artift will not derive from chem- iflry all the advantages he has a right to expect, until he has broken through that powerful barrier which fufpicion, felf-love, and prejudice have raifed between the chemift and himfelf. Suchphilofophers as have attempted to pafs this line, have frc- PRELIMINARY DISCOURSE. 3f •tuently been repelled as dangerous innovators ; and prejudice, which reigns defpotically in manufactories, has not even permit- ted it to be thought the proceffes were capable of improvement. It is eafy to fliew the advantages which the arts might obtain from chemiflry, by cafting a retrofpect over its applications to each of them in particular. i. It appears, from the writings of Columella, that the an- cients poffcffed a confiderable extent of knowledge refpecting agriculture, which was at that time confidered as the firft and hobleft occupation of man. But when once the objects of lux- ury prevailed over thofe of neceflity, the cultivation of the ground was left to the mere fucceflion of practice, and this firft of the arts became degraded by prejudices. Agriculture is more intimately connected with chemiflry than is ufually fuppofed. It muft be admitted that every man is ca- pable of caufing ground to bear cotn ; but what a confiderable extent of knowledge is neceffary to caufe it to produce the greateft poflible quantity ! It is not enough, for this purpofe, to divide, to cultivate and to manure any piece Of ground : a mix- ture is likewife required of earthy principles fo well afforted, that it may afford a proper nourifh'ment; permit the roots to extend themfelves to a diftance, in order to draw up the nutri- tive juices ; give the ftein a fixed bafe ; receive, retain, and af- ford upon occafion, the aqueous principle, without which no vegetation can be performed. It is therefore effential to afcer- tain the nature of the earth, the avidity with which it feizes water, its force of retaining it, &c. j and thefe requifites point to ftudies which will afford principles not to be obtained by mere practice but flowlyand imperfectly. Every grain requires a peculiar earth. Barley vegetates free- ly among the dry remains of granite ; wheat grows in calcare- ous earth, &C. And how can it be poflible to naturalize for- eign products, without a fufficient ftock of knowledge to fupply them with an earth fimilar to that which is natural to them ? The diforders of grain and forage, and the deftruction of the infects which devour them, are objects of natural hiftofy and chemiflry : and we have feen in our own times the effential art of drying and preferving grain, and all thofe details which are interefting in the preparation of bread, carried by the labours of a few chemifts to a degree of perfection which feemed difficult to have been attained. The art of difpofing ftables in a proper manner, that of choof- ing water adapted for the drink of domeftick animals, the econ- omical procefles' for preparing and mixing their food, the un- common talent of fupplying a proper manure fuited to the na. 34 PRELIMINARY DISCOURSE. ture of foils, the knowledge neceffary to prevent or to repair the effects of blights—all come within the province of chemiflry; and without the affiftance of this fcience our proceeding would be painful, flow, and uncertain. We may at prefent infill upon the neceflity of chemiflry in the various branches of agriculture with fo much the more rea- fon, as government does not ceafe to encourage this firft of arts by recompenfes, diftinctions, and eftabliftiments ; and the views of the ftate are forwarded by the propofal of means to render this art flourifhing. We fee, with the greateft fatisfaction, that, by a happy turn of reflection, we begin to confider agriculture as the pureft, the moft fruitful, and the moft natural fource of our riches. Prejudices no longer tend to opprefs the huf- bandman. Contempt and fervitudc are no longer the inherit- ance received for his iiiceffant labours. The moft ufeful and the moft virtuous clafs of men is likewife that whofe ftate is moft minutely confidered ; and the cultivator of the ground in France is at lait permitted to raife his- hands in a ftate of free- dom to heaven, in gratitude for this happy revolution. 2. The working of mines is likewife founded upon the prin- ciples of chemiltry. This fcience alone points out and directs the feries of operations to be made upon a metal, from the mo- ment of its extraction from the earth until it comes to be ufed in the arts. Before the chemical analyfis was applied to the examination of ftones, thefe fubftances were all denoted by fuperficial char- acters, fuch as colour, hardnefs, volume, weight, form, and the property of giving fire with the ft eel. All thefe circumftances had given rife to methods of divifion in which every other prop- erty was confounded ; but the fucceffive labours of Pott, Mar- graaff, Bergmann, Scheele, Bayen, Dietrich, Kirwan, Lavoifier> T)e Morveau, Achard, Sage, Berthollet, Jerhard, Erhmann, Fourcroy, Mongez, Klaproth, Crell, Pelletier, De la Metherie, &c. by inftructing us concerning the conftituent principles of every known flone, have placed thefe fubftances in their.prop- er fituations, and have carried this part of chemiflry to the fame degree of precifion as that which we before poffeffed refpecting the neutral falts. The natural hiflory of the mineral kingdom, unaflifted by chemiflry, is a language compofed of a few words, the knowl- edge, of which has acquired the name of Mineralogift to many perfons. The words Calcareous Stone, Granite, Spar, Schorle, Feld Spar, Schiftus, Mica, &c. alone compofe the dictionary of feveral amateurs, of natural hiflory ; but the difpofition of thefe fubftances in the bowels of the earth, their refpective pofition PRELIMINARY DISCOURSE. 35 in the compofition of the globe, their formation and fucceflive . decompofitions, their ufes in the arts, and the knowledge of their conftituent principles, form a fcience which can be well known and inveftigated by the chemift only. It is neceffary therefore that mineralogy fhould be enlighten- ed by the ftudy of chemiflry ; and we may obferve that, fince thefe two fciences have been united, the labour of working mines has been Amplified, metallick ores have been wrought with more intelligence, feveral new metallick fubftances have been difcovered, individuals have opened mines in the provinces ; and we have become familiar with a fpecies of induftry which feemed foreign, and almoft incompatible with our foil and our habits. Steel and the other metals have received in our manu- factories that degree of perfection which had till lately excited our admiration, and humilitated our felf-love. The fuperb manufacture of Creufot has no equal in Europe. Moft of our works are fupported by pit-coal; and this new combuftible fub- ftance is fo much the more valuable, as it affords us time to re- pair our exhaufted woods, and as it is found almoft every where in thofe barren foils which repel the ploughfhare, and prohibit every other kind of induftry. The eternal gratitude of this country is therefore due to Meflrs. Jars, Dietrich, Duhamel, Monet, Genfanne, &c. who firft brought us acquainted with thefe true riches. The tafle for mineralogy, which has diffufed itfelf within our remembrance, has not a little contributed to produce'this revolution ; and it is in a great meafure owing to thofe collections of natural hiflory, againft which fome perfons have fo much exclaimed, that we are indebted for this general tafte. Our collections have the fame relation to natural hiflory, as books bear to literature and the fciences. The collection frequently is nothing more than an object of luxury to the pro- prietor ; but in this very cafe it is a refource always open to the man who is defirous of beholding, and inftructing himfelf. It is an exemplar of the works of nature, which maybe confult- ed every moment ; and the chemift who runs over all thefe •productions, and lubjects them to analyfes to afcertain their conftituent principles, forms the precious chain which unites •nature and art. 3. While the chemift attends to the nature of bodies, and en- deavours to afcertain their conftituent principles, the natural philofopher ftudies their external characters, and as it were their phyfiognomy. The object of the chemift ought therefore to be ur.ited to that of the philofopher, in order to acquire a complete idea of a body. What in fact fhall we call Air or iFire, without the inftruction of the chemift ? Fluids more or 36* PRELIMINARY DISCOURSE. lefs compreflible, ponderous and elaftick. What are the par- ticulars of information which natural philofophy affords us con- cerning the nature of folids ? It teaches us to diftinguifh them from each other, to calculate their weight, to determine their figure, to afcertain their ufes, &c. If we call our attention upon the numerous particulars which chemiflry has lately taught us refpecting air, water, and fire, we fhall perceive how much the connexion of thefe two fcience^ has been ftrengthened. Before this revolution, natural philofo- phy was reduced to the fimple difplay of machines ; and this coquetry, by giving it a tranfient glare, would have impeded its progrefs, if chemiflry had not reftored it to its true deflination. The celebrated chancellor Bacon compared the natural magick, or experimental philofophy, of his time, to a magazine in which a few rich and valuable moveables were found among a heap of toys. The curious, fays he, is exhibited inftead of the ufeful. What more is required to draw the attention of great men, and to form that tranfient faflnon of the day which ends in con- tempt ? The natural philofophy of our days no longer defervcs the re- proaches of this celebrated philofopher. It is a fcience found- ed on two bafes equally folid. On the one part, it depends on mathematical fcience for its principles; and, on the other it refls upon, chemiflry. The natural philofopher will attend equally to both fciences. The ftudy of chemiflry, in certain departments, is fo inti- mately connected with that of natural philofophy, that they are jmfeparable ; as, for example, in refearches concerning air, wa- ter, fire, &c. Thefe fciences very advantageoufly affifl each other in other refpects i and while the chemift clears minerals from the foreign bodies which are combined with them, the philofopher fupplies the mechanical apparatus neceffary for ex- ploring them. Chemiflry is infeparable. from natural philofo- phy, even in fuch parts as appear the moft independent of it ; fuch, for example as opticks, where the natural philofopher can make no progrefs but in proportion as the chemift fhall bring his glafs to perfection. The connection between thefe two fciences is fo intimate, - that it is difficult to draw a line of diftinction between them. If we confine natural philofophy to enquiries relative to the ex- ternal properties of bodies, we fhall afford no other object but the mere outfide of things. If we reflrain the chemift to the mere analy fis, he will at moft arrive at the knowledge of the conftituent principles of bodies, and will be ignorant of PRELIMINARY DISCOURSE. 37 their functions. Thefe diftinctions in a fcience which has but one common purpofe, namely, the complete knowl- edge of bodies, cannot longer exift ; and it appears to mc that we ought abfolutely to reject them in all objects which can pnly be well examined by the union of natural philofophy and chemiflry. At the period of the revival of letters^it was of advantage to fep- arate the learned, as it Were, upon the road to truth; and to multif ply the workfhops,if I may ufe the expreflion, to haften the clear- ing away. But at prefent, when the various points are re-united, and the connection between the whole is feen, thefe feparations, thefe divifions, ought to be effaced ; and we may flatter ourfelves that, by uniting our efforts, we may make a rapid progrefs in the ftudy of nature. The meteors, and all the phenomena of which the atmofphere is the grand theatre, can be known only by this re-union. The decompofition of water in the bowels of the earth, and its formation in the fluid which furrounds us, cannot t>ut give rife to the moft happy and the moft fublime applica- tions. 4. The connection between chemiflry and pharmacy is fo intimate, that thefe two fciences have long been confidered a» one and the fame ; and chemiflry, for a long time, was culti- vated only by phyficians and apothecaries. It muft be allowed that, though the chemiflry of the prefent day is very different from pharmacy, which is only an application of the general prin- ciples of this fcience, thefe applications are fo nurq^rous, the clafs of perfons who cultivate pharmacy is in general fo well in- formed, that it is not at all to be wondered at, that moft apoth- ecaries fhould endeavour to enlighten their profeflion by a feri- Ous ftudy of chemiflry, and by the happieft agreement unite the knowledge of both parts of fcience. The abufes which, at the beginning of the prefent century, were made of the applications of chemiflry to medicine, have caufed the natural and intimate relations of this fcience with the art of healing to be miflaken. It would have been more pru- dent, no doubt, to have rectified its applications; but unfortu- nately we have too much ground to reproach phyficians forgo- ing to extremes. .They have, without reftriction, banifned that which they before receive i without examination ; and we have feen them fucceffively deprive their art of all the afliftance it might obtain from the auxiliary fciences. In order to direct with propriety the applications of chemiflry to the human body, proper views mutt be adopted relating to the animal economy, together with accurate notions of chemif- 33 PRELIMINARY DISCOURSE. • try itfelf. The refults of the laboratory muft be confidered as iubordinate to phyfiological obfervations. We fhould endeav- our to enlighten the one by the other, and to admit no truth as eftablifhed which is contradicted by any of thefe means of con- viction. It is in confequence of a departure from thefe prin- ciples that the human body has been confidered as a lifelefs and paflive fubftance; and that the drift principles obferved in the operations of the laboratory have been applied to this living fyf- tein. In the mineral kingdom, every thing is fubjected to the inva- riable laws of the affinities. No internal principle modifies the action of natural agents ; and hence it arifes that we are capa- ble of foretelling, producing or modifying the effects. In the vegetable kingdom, the action of external agents is e- 4 inm body, are likewife among the benefits arifing from this fcience. 5. Chemiflry is not only of advantage to agriculture, phyfick, mineralogy, and medicine, but its phenomena are interefting to all the orders of men : the applications of this fcience are fo numerous, that there are few circumftances of life in which the chemift does not enjoy the pleafure of feeing its principles ex- emplified. Moft of thofe facts which habit has led us to view with indifference are interefting phenomena in the eyes of the chemift. Every thing inftructs and amufes him ; nothing is in- different to him, becaufe nothing is foreign to his purfuits ; and nature, no lefs beautiful in her moft minute details than fublime in the difpofition of her general laws, appears to difplay the whole of her magnificence only to the eyes of the chemical phi- lofopher. We might eafily form an idea of this fcience, if it were pofli- ble to exhibit in this place even a fketch of its principal appli- cations. We fhould fee, for example, that chemiflry affords us all the metals of which the ufes are fo extenfive ; that chemiflry affords us the means of employing the parts of animals and of plants for our ornament : that our luxuries, and our fubfiftence, are by this fcience eftablifhed as a tax upon all created beings ; and that by this power we are taught to fubject nature to our wants, our tafte, and even to our caprices. Fire, that free, inde- pendent element, has been collected and governed by the induf- try of the chemift ; and this agent, deftined to penetrate, to en- liven, and to animate the whole of nature, has in his. hands be- come the agent of death, and the prime minifterof deftruction. The chemifts who in our time have taught US' to infulate that pure air which alone is proper for combuftion, have placed in our hands, as it were, the very effence of fire : and this ele- ment, whofe effects were fo terrible, becomes the agent of ftill more terrible confequences. The atmofphere, which was form- erly confidered as a mafs of homogeneous fluid, is now found to be a true chaos, from which analyfis has obtained principles fo much the more interefting to be known, as nature has made them the principal agents of her operations. We may confider this mafs of fluid in which we live as a vaft laboratory, in which the meteors are prepared, in which all the feeds of life and death are developed, from which nature takes the elements of the compofition of bodies, and to which their fubfequent decompo- fition returns the fame principles which were before extracted. Chemiflry, by informing us of the nature and principles of bodies, inftructs us perfectly concerning our relation to the ob- jects around us. This fcience teaches us, as it were, to five 40 PRELIMINARY DISCOURSE. with them ; and impreffes a true life upon them, fince by thi* means each body has its name, its character, its ufes, and its in- fluence, in the harmony and arrangement of this univerfe. The chemift, ,in the mid ft of thofe numerous beings which the common race of men accufe nature of having vainly placed upon our globe, enjoys the profpect as it were in the centre of a fociety, all whofe members are connected together by inti- mate relations, and concur to promote the general good. Iri his fight every thing is animated, every being performs a part on this vaft theatre ; and the chemift who participates in thefe interefting fcenes, is repaid with ufury for his firft exertions to difcover the relations exifting between them. We may even confider this commerce, or mutual relation between the chemift and nature, as very proper to foften the manners, and to imprefs on the character that freedom and firm- nefs of principle fo valuable in fociety. In the ftudy of natural hiflory, no caufe ever prefents itfelf to complain of inconftancy or treachery. An attachment is eafily contracted for objects which afford enjoyment only ; and thefe connections are as pure as their object, as durable as nature, and ftronger in pro- portion to the exertions which have been required to eftablifh them. From all thefe confiderations, there is no fcience which more eminently deferves to enter into the plan of a good education than chemiflry. We may even affirm that the ftudy of this fcience is almoft indifpenfably neceffary to prevent us from being Itrangersin the midftofthe beings and phenomena which furround us. It is true indeed that the habit of beholding the objects of? nature may produce a knowledge of fome of their principal prop- erties. We may even in this way arrive at the theory of fome of the phenomena. But nothing is more proper to check the pre- tentions of young perfons, who are elevated by fuch imperfect acquifitions, than to fhew them the vaft field cf which they are ignorant. The profoundeft fentiment- of their ignorance will be feconded by the natural defire of acquiring new knowledge. The wonderftl properties of the objects prefented to them will engage their attention. The interefting nature of the phenom- ena will tend to excite their curiofity. Accuracy of experiment* and ftrictnefs of refult, will form their reafoning powers, and render them fevere in their judgment. By ftudying the prop- erties of all the bodies which furround him, the young fcholar learns to know their relation with himfelf ; and by fucceflively attending to all objects, he extends the circle of his enjoyment by new conquefts. He becomes a partaker in the privileges of the Creator, by uniting and difuniting, by compounding and de* PRELIMINARY DISCOURSE. f\ ftroying. We might even affirm that the Author of nature, re- ferving to himfelf alone the knowledge of his general laws, has placed man between himfelf and matter, that it may receive thefe laws from his hands, and that he may apply them with proper modifications and restrictions. In this view, therefore, we may confider man as greatly fuperiour to the other beings which com- pofe this living fyftem. They all follow a monotonous and in- variable procefs; receive the laws, and fubmit to effects without modification. Man alone pofieffes the rare advantage of know- ing a part of thefe laws, of preparing events, of predicting re- fults, of producing effects at pleafure, of removing whatever is noxious, of appropriating whatever is beneficial, of compofing fubftances which nature herfelf never forms; and, in this laft point of view,.himfelf a Creator, he appears to partake with the Supreme Being in the moft eminent of his prerogatives. pirn Elements of Chemistry. PART THE FIRST. CONCERNING THE CHEMICAL PRINCIPLES. INTRODUCTION. Definition of Chemiflry ; its Object and Means—Defcription of a Lab- oratory, and the principal Inftruments employed in chemical Opera- tions, with a definition of thofe Operations. C^HEMISTRY is a fcience, the object of which is to afcertain the nature and properties of bodies. The methods ufcd to obtain this knowledge are reducible to two ; analyfis and fynthefis. The principal operations of chemiflry are performed in a place calkd a Laboratory. A laboratory ought to be ejctenfive and well aired, in order to prevent dangerous vapours from remaining, which are pro- duced in fome operations, or which may.efcape by any unfore- seen accident. It ought to be dry, becaufe otherwife iron veflels would ruft, and moll of the chemical products wduld be liable to change. But the principal excellence of a laboratory confifts in its being furnifhed with all thofe inftruments which may be employed in the ftudy of the nature of bodies, and in enquiries refpecting their properties. Among thefe inftruments there are fome which are of gen* eral ufe, and applicable to moft operations ; and there are others which ferveonly for peculiar ufes. This divifion immediately points out that, at the prefent inftant, we can only treat of the former, and that we muft defcribe the others on fuch occafiona as will render it neceffary to treat of their ufes. The chemical inftruments moft frequently employed are thofe which prefent themfelves firft to view upon entering a laborato- ty j namely, the furnaces. 44 Evaporatory Furnace. Chemical Veffcls. Thefe furnaces confift of earthen veffels appropriated to the various operations performed upon bodies by means of fire. A proper mixture of fand and clay is commonly the material of which thefe veffels are formed. It is difficult, and even im- pofiible, to prefcribe and determine* according to any invariable method, the proportions of thefe conftituent parts ; becaufe they muft be varied according to the nature of the earth made ufe of. Habit and experience alone can furnifh us with princi- ples on this fubject. The feveral methods of applying fire to fubftances under ex, amination, has occafioned the conftruction of furnaces in differ- ent forms, which we fhall at prefent reduce to the three follow- I. The evaporatory furnace.—-This furnace has received its name from its ufe. It is ufed to reduce liquid fubftances into vapour by means of heat, in order to feparate the more fixed principles from thofe which are more ponderous ; «*nd were mixed, fufpended, compounded, or diflblved in the fluid. ' The fire-place is covered by the evaporatory veffel. Two or three grooves, channels, or depreflions are made in the fides of the furnace near its upper edge, to facilitate the drawing of the fire. The veffel which contains the fubftance to be evaporated, is called the evaporatory veffel. Thefe veffels are formed of earth, glafs or metal. Veffels of unglazed earth are too porous, infomuch that liquids filtrate through their texture. Thofe of porcelain bifcuit are likewife penetrable by liquids ftrongly heated, and fuffer gafeousor aeri- form fubftances to efcape. The beautiful experiments of Mr. D'Arcet upon the combuftion and deftruction of the diamond, in balls of porcelain, are well known and tend to illuftrate this fubject. I have confirmed thefe refults by experiments in the large way, upon the diftillation of aqua-fortis, which lofes as well in quality as quantity when the procefs is carried on in vef- fels of porcelain clay. Glazed earthen veffels cannot be ufed when the glafs con- fifts of the calces of lead or copper ; becaufe thofe metallick matters are attacked by acids, fats, oils, &c. Neither can earth- en veffels be ufed which are covered with enamel, becaufe this kind of opaque glafs is almoft always full of fmall cracks, through which the liquid would introduce itfelf into the body of the veffel. Earthen veffels cannot therefore be ufed, excepting in opera- tions of little delicacy1, in which precifion and accuracy are not indifpenfably required. Application of Heat. 45 Evaporatory veffels of glafs are in general to be preferred. Thofe which refill the fire better than any others, are prepared in the laboratory, by cutting a Iphere of glafs or a receiver into two equal parts with a red-hot iron. The capfules which are made in the glafs-houfe, are thickcil at the bottom, and confc- quently more liable to break at that part when expofed to the fire. Evaporatory veffels of metal are ufed in manufactories. Cop- per is moft commonly employed, becaufe it not only poffeffes the property of refilling fire, but has a confiderable degree of folidi- ty, together with the facility of being wrought. Alembicks are made of this metal, for the diftillation of vinous fpirits, and aro- raatick fubftances; as are alfo cauldrons or pots for the cryftalliza- tion of certain falts, and for feveral dying proceffes, &c. Lead is likewife of confiderable ufe, and is made choice of whenever op- erations are to be performed upon fubftances which contain, the fulphurick acid, fuch as the fulphates of alumine and of iron ; and for the concentration and rectification of the oil of vitriol. Tin veffels are alfo employed in fome operations : the fcarlet bath affords a more beautiful colour in boilers of this metal than in thofe of any other. Capitals of tin have already begun to be fubilituted in the room of thofe of copper, in the conflruction of alembicks; and by this means the feveral products of diftil- lation are exempted from every fufpicion of that dangerous me- tal. Boilers of iron are likewife ufed for certain coarfe opera- tions : as, for example, in the concentration of the lixiviums of common fait, of nitre, &c. Evaporatory veffels of gold, of filver, or of platina, are to be preferred in fome delicate operations-, but the price and fcarci- ty of thefe veffels do not permit them to be ufed, efpeciallv in the large way. Moreover it is from the nature of the fubftance to be evapo- rated, that we muft determine the choice of the veffel moft fuit- able to any operation. There is no particular kind of veffel which can be adapted exclufively on all occafioife. It may only be obferved, that glafs prefents the greateft number of advanta- ges, becaufe it is compofed of a fubftance the leaft attacked, the leafl foluble, and the leaft deftructible, by chemical agents. Evaporatory veflels are known by the name of capfules, cu- curbits, Sec. according to their feveral forms. Thefe veffels ought in general to be very wide and fhallow, in order that the diftillation and evaporation may be fpeedy and oeeonornical. It is neceffary, uThat the evaporatory veffel be not narrow at its upper part. 2. That the heat be applied to the liquid in all parts and equally. 3. That the column or mafs 4<* *Baths. Ziibfimafion. of the liquid fhould have little depth, and a large furfaoe of evaporation. It is upon thefe principles that 1 have conftructed in Languedoc, boilers proper for diftilling brandy, which fave eleven twelfths of the time, and four fifths of the combuftibles. Evaporation may be performed in three manners. I. By a naked fire. 2. By the fand bath. 3. By the water bath. Evaporation is made by a naked fire, when there is no fur> fiance interpofed between the fire and the veffel which contains the liquid intended to be evaporated ; as, for example, when water is boiled in a pot. Evaporation is performed by the fand bath, when a veffel filled with fand is interpofed between the fire and the evapora- tory veffel. The heat is in this cafe communicated more flowly and gradually ; and the veffels, which would otherwife have beenbroken by the immediate application of the heat, are ena- bled to refifl its force. The heat is at the fame time more equally kept up ; the refrigeration is more gr-adual ; and the operations are performed with a greater degree of order, precifr ion, and facility. If, inftcad of employing a veffel filled with fand, we ufe a vef- fel of water, and the evaporatory veffel be plunged in the li* quid, the evaporation is faid to be made on the water bath : in this cafe, the fubftance to be evaporated is only heated by communication from the water. This form or method of evap- oration is employed when certain principles of great volatility, fuch as alcohol, or the aromatick principles of plants, are to be extracted or diftilled. It poffeffes the advantage of affording products which are not changed by the fire, becaufe the heat is tranfmitted to them by the intervention of a liquid : it is this circumftance which renders the procefs valuable for the extrac- tion of volatile oils, perfumes, ethereal liquids, &c. It poffeffes the advantage of affording a heat nearly equal, becaufe the de- gree of ebullition is a term nearly conltant; and this ltandard beat may be graduated or varied at pleafure, by adding falts to the liquid of thi water bath, becaufe this fingle circumftance renders the ebullition more or lefs quick and eafy. The fame effect may likewife be produced bv reftraining the evaporation ; for in this cafe the liquid may affume a degree of heat much «aore confiderable, as is feen in the digefter of Papin, fleam en- gines, eolipiles, and the boilers for ftriking the red tinge in cot- ton. Sublimation differs from evaporation, becaufe the fubftance to be raifed is folid. The veffels ufed in this operation are known by the name of fublimatory veffels. Thefe -are com- monly globes terminating in a long neck : they are then calhjd> mattraffes. Reverberatory Furnace. Retortu 4.J Iri order to fublime any fubftance, a part of the ball of the fnattrafs is furrounded with fand. The matter which is volatile ized by the heat, rifes, and is condenfed againft the coldeft part of the veffel; where it forms a ftratum or cake, that may be tak- en out by breaking the veffel itfelf. In this manner it is that fal ammoniack, corrofive fublimate, and other fimilar products^ are formed for the purpofes of commerce. Sublimation is ufually performed either for the purpofe of purifying certain fubftances, and difengaging them from extra- neous matters; or elfe to reduce into vapour, and combine under that form, principles which would have united with greac difficulty if they had not been brought to that ftate of extreme- divifion. II. The reverberatory furnace.—-The name of the reverbera- tory furnace has been given tothat conftruction-which is appro- priated to diftillation. This furnace is compofed of four parts: f. The afh-hole, intended for the free paffage of the air, and to receive the afhe* or refidue of the cumbuilion. 2. The fire-place, feparated. from the afh-hole by the grate, and in which the combuftible- matter is contained. 3. A portion of a cylinder, which is called the laboratory, becaufe it is this part which receives the retorts employed in the operations or diftillations. 4. Thefe three pieces are covered with a dome, or portion of a fphere, pierced near its upper part by an aperture, which affords a free paffage to the current of air, and forms a chimney. The moft ufuaJ form of the reverberatory furnace is that of a cylinder terminat- ed by a hemifphere, out of which arifes a chimney of a greater or lefs length, to produce a fuitable degree of afpiration. In order that a reverberatory furnace may be well propor- tioned, it is neceffary,. 1. That the afh-hole fhould be large, to admit the air frefh and unaltered. 2. That the fire-place and laboratory together fhould have the form of a true ellipfis, whofe two foci fhould be occupied by the fire and the retort. la this cafe all the heat, whether direct or reflected, will ftrike the retort. The reverberatory furnace is ufed for diftillation. Diftilla- tion is that procefs by which the force of fire is applied to dis- unite and feparate the feveral principles of bodies, according to the laws of their volatility, and their feveral affinities. Diftilling veffels are known by the name of retorts. Retorts are formed of glafs, of ftone ware, of porcelain, or of metal ; thefe fubftances being refpectively ufed, according to jhe nature of the bodies intended to be sxpoied to diftil*. latioa. 45 Receivers. Forge Furnace. Crucibles. Whatever be the nature of the material, the forms of re- torts are the fame. , This figure refembles an egg, terminating in a beak or tube, which diminifhes infenfibly in diameter, and is flightly inclined or bended. The oval portion of the retort, which is called its belly, is placed in the laboratory of the furnace, and is fupported upon , two bars of iron, which feparate the laboratory from the fire- place ; while the beak or neck of the retort iffues out of the furnace through a circular aperture formed in the edges of the dome and of the laboratory. A veffel intended to receive the product of the diftillation iV fitted to the neck of the retort. This veffel is called the recip- ient, or receiver. The receiver is commonly a fphere with two apertures ; the one of confiderable magnitude, to receive the neck of the re- tort ; the other fmaller, to afford vent for the vapours. This part is called the tubulure of the receiver ; whence the terms tubulated receiver, or receiver not tubulated, &c. Though the reverberatory furnace be particularly adapted to diftillation, this operation may be performed on the fand-bath : and here, as in other cafes, it depends fingly on the intelligence of the artift to vary his apparatus according to the neceflity of *> circumftances, and the nature of the fubftances upon which he operates. The conftruction of thefe furnaces may likewife be varied ; and the chemift will find it neceffary to learn the art of availing himfelf of every apparatus he poffeffes, to carry his operations into execution: for if he fhould perfuade himfelf that it is im- poffible to proceed in chemical refearch, excepting in a labora- tory provided with all fuitable veffels ; he may let the moment pafs in which a difcovery might be made, but which may not again return. And it may truly be faid, that he who treads fervilely in the paths of others who have gone before him, will never attain to the difcovery of new truths. III. The forge furnace.—The forge furnace is that in which the current of air is determined by bellows. The afh-hole, the fire-place, and the laboratory are here all united together, and this affemblage forms only a portion of a cylinder, pierced near the lower angle by a fmall hole, into which the tube of the bel- lows enters. This part is fometimes covered with a hemifphere or dome, to concentrate the heat with greater efficacy, and to reflect it upon the bodies expofed to it. The forge furnace ia employed in the fufion and calcination of metals, and generally for all the operations which are performed in crucibles. By crucibles we underftand veffels of earth or metal, which are almoft always of the form of an inverted cone. A cruci- Various Fuels. Lutes and Coatings for Retorts. 49 Lie ought to fupport the ftrongeft heat without melting : it ought to refift the attacks of all fuch agents as are expofed to heat veffels of this kind. Thofe crucibles which poffefs the greateft degree of perfection, are made in Heffe or in Holland. I have made very good ones by a mixture of raw and unbaked clay from Salavas in the Vivarais. Our laboratories have been provided with crucibles of platina, which unite the moft excellent properties. They are nearly in- fufible, and at the fame time indeftructible by the fire. The feveral earthen veffels concerning which we have here treated, may be fabricated by the hand* or wrought in the lathe. The firft proceeding renders them more folid, the clay is better united, and it is the only method ufed in glafs manufactories ; but the fecond method is more expeditious. The agent of fuch decompofitions as are effected by means of furnaces, is fire. It is afforded by the combuflion of wood, pit-coal, or charcoal. Wood is only employed in certain large works ; and we pre- fer charcoal in our laboratories, becaufe it does not fmoke, has no bad fmell, and burns better in fmall maffes than other com- buftibles. We choofe that which is the moft fonorous, the dri- eft, and the leaft porous. But, in the feveral operations we are about to defcribe, it is neceffary to defend the retorts from the immediate action of the fire ; and alfo to coerce and reftrain the expanfible vapours, which are very elaftick, and frequently corrofive. It is to an- fwer thefe purpofes that various lutes are employed. ' r. A glafs retort expofed to the action of the fire would in- fallibly break, if the operator were not to have recourfe to the prudent precaution of coating it with earth. I have found it advantageous for the coating of retorts, to ufe a mixture of fat earth and frefh horfe dung: for this pur- pofe, the fat earth is fuffered to rot for fome hours in water; and when it is morftened, and properly foftened, it muft be kneaded with the horfe dung, and formed into a foft pafte, which is to be applied and fpread with the hand upon every part of the re- tort intended to be expofed to the action of the fire. The horfe dung combines feveral advantages. 1. It contains a ferous fluid, which hardens by heat, and ftrongly connects all the parts together : when this juice has been altered by fermentation or age, the dung does not poffefs the fame virtue. 2. The fila- ments or flalks of hay, which are fo eafily diftmguifhed in horfe dung, unite all the parts of the lute together..■■■' Retorts luted in this manner refift the impreflion of the fire very well j and the adheficn of the lute to the retort is fuck, G 5» Lutes. 7Troulfe's Apparatus. that even fhould the retort fly during the operation, the diftilla- tion may be ftill carried on, as I have daily experience in works in the large way. 2. When it is required to coerce or oppofe the efcape of the vapours which are difengaged during any operation, it is no doubt fufficient if the joinings pf the veffels be covered with paper glued on, or with flips of bladder moiftened with the lute of lime and white of egg, provided the vapours be neither dangerous nor corrofive ; but, when the vapours are corrofivey it is neceffary to ufe the fat Jute to retain them. Fat lute is made with boiled linfeed oil mixed and well in- corporated with fifted clay. Nut oil, kneaded with the fame clay, forms a lute poffefling the fame properties. It is eafily ex- tended in the hand,' and is ufed for defending the joinings of veflels, upon which it is afterwards fecured by ftrips of linen, dipped in the lute of lime and white of egg. Before the appli- cation of heat in any diftillation, it is neceffary firft to fuffer the lutes to dry. Without this precaution the vapours would rife and efcape -, or otherwife they would combine with the water which molftens the lutes, and would corrode and de- ftroy the bladder, the fkin, the paper,, and in a wo»d, every fub-' fiance ufed to fecure them in their places. The lute of lime and the white of egg. dries very fpeedily, and muft be ufed the moment it is made. This lute, likewife, oppofes thegreateft vefifiance to the efcape of the vapours, and adheres the moft intimately to the glafs. It is made by mixing a fmall quantity of finely-powdered quick-lime with white of egg, and after- wards beating up the mixture to facilitate the combination. It muft then be inftantly applied on pieces of old linen, to be wrapped round the places of joining. In the large works, where it is not poflible to attend to all thefe minute details, the joinings of the retort and receiver are- luted together with the fame lute which is ufed to coat the re- torts. A covering of the fhicknefs of a few lines is fufficient to prevent the vapours of the marine or nitrous acid from ef- caping. As in certain operations a difengagement takes place of fo prodigious a quantity of vapours, that it is dangerous to confine them ; and as, on the other hand, the fuffering them to efcape would occafion a confiderable lofs in the product; an apparatus has been contrived of great ingenuity and fimplicity to moderate the iffue, and to retain without rifle fuch vapours as would other- wife efcape. This apparatus is known by the name of its au- thor, Mr. Woulfe, a famous Englifh chemift. His moft excel- lent procefs confifts in adapting the extremity of a recurved tube. Wouife's Appcratus. 51 to the tubulure of the receiver ; the other end of which is plung- ed into water, in a bottle half filled, and properly placed for that purpofe. From the empty part of this bottle iffues a fecond ■tube, which is in like manner plunged in the water of a fecond bottle. A number of other bottles may be added, obferving the fame precautions ; with the attention, neverthelefs, to leave the laft open, to give a free efcape to the vapours which are not co- ercible : and, when the apparatus is thus difpofed, all the join- ings are to be luted. It will eafily be imagined that the vapours which efcape from the retort are obliged to pafs through the tube adapted to the tubulure of the receiver, and confequently muft pafs through the water of the firft bottle : they therefore fuffer a firft refifiance, which partly condenfes them. But as almoft all vapours are more or lefs mifcible and foluble in water, a calculation is previouily made of the quantity of water necef- fary to abforb the vapours which are difengaged from the mix- ture in the retort ; and care is taken to diftribute this proper quantity of water in the bottles of the apparatus. By this means we obtain the pureft and moft concentrated products ; becaufe the water, which is always the receiver, and is the vehicle of thefe fubftances, becomes faturated with them. There is, perhaps, no other method of obtaining pro- ducts always of an equal energy, and comparable in their ef- fects ; a circumftance of the greateft importance in the opera- tions of the arts, as well as in philofophical experiments. I have applied this apparatus to works in the large way ; and I ufe it to extract the common muriatick acid, the oxigenated muriatick acid, ammoniack or volatile alkali, &c. As it would very often happen, in this apparatus, that the preffure of the external air would caufe the water of the outer \eflels to pafs into the receiver, in confequence of the fimple re- frigeration of the retort ; this inconvenience has been obviated, by inferting a ftraight tube into the necks of the firft and fecond bottles, to fuch a depth, that its lower end is plunged into the water, while its other end rifes feveral inches above the neck of the bottle. It may eafily be conceived, as a confequence of this difpofition, that when the dilated vapours of the receiver and retort are condenfed by cooling, the external air will rufh through thefe tubes to eftablifh the equilibrium ; and water can- not pafs from the one to the other. Before the invention of this apparatus, it was ufual to drill a hole in the receiver,which was kept clofed, and only opened from time to time for the efcape of the vapours. This method was in- convenient in many refpects. In the firft place, and principal- ly, becaufe, in fpite of all precautions, it was attended with the 5 2 Woulfe's Apparatus. Balances, &c. rifk of an explofion every moment, by the irregular difengage- ment of the vapours, and the impoffibility of calculating the the quantity produced in a given time. A fecond inconven- ience was, that the vapours which thus efcaped occafioned a confiderable lofs in the product, and even weakened the remain- der ; becaufe this volatile principle confifted of the ftrongeft part. A third inconvenience was, that the vapours which did efcape incommoded the artift to fuch a degree, that it was im- poffible to perform moft of the operations of chemiflry in the courfe of a lecture, where a confiderable number of auditors were prefent. Thus it is that the apparatus of Woulfe unites a number of advantages : on the one hand, economy in the proceffes, and fuperiority in the product; on the other hand, fafety for the chemift and his afliftants : and in every point of view the au- thor is entitled to the beft acknowledgments of chemifts, who were too often fo much affected with thefe unwholefome exhala- tions, that their health was either totally deftroyed, or they fell abfolute victims to their zeal for the promotion of fcience. It is neceffary that a laboratory fhould be provided with bal- ances of the utmoft accuracy ; for the chemift, who very fre- quently operates only upon fmall quantities, ought to be able by the ftrictnefs of his operations, and the accuracy of his appara- tus, to produce refults comparable with thofe of works in the large way. It frequently happens that the fimple effay of a fpeci- men of an ore determines the opening of a mine : and it fcarce- ly need be pointed out, of how great confequence it is to remove every caufe of errour from the operations of chemiflry ; fince the flightefl errour in the works of the laboratory may be attend-. ed with the moft. unhappy confequences, when the application of the principles is made to works in the large way. We fhall treat of other veffels and of the chemical apparatus, in proportion as we fhall have occafion to make ufe of them ; for it appears to us that, by thus connecting the defcription with their ufe, we fhall fucceed better in rendering them intelligible to the reader, at the fame time that his memory will be lefs fa- tigued. Affinity of Aggregatisn. 53 SECTION I. Concerning the General Law which tends to bring the Particles of Bo- dies together, and to maintain them in a State of Mixture or Com- bination. X HE Supreme Being has given a force of mutual at- traction to the particles of matter ; a principle which is alone fufficient to produce that arrangement which the bodies of this univerfe prefent to our obfervation. As a very natural confe- quence of this primordial law, it follows that the elements of bodies muft have been urged towards each other ; that maffes muft have been formed by their re-union; and that folid and com- pact bodies muft have infenfibly been conftituted ; towards which, as towards a centre, the lefs heavy and lefs compact bod- ies muft gravitate. This law of attraction, which the chemifts call Affinity, tends continually to bring principles together which are difunitcd, and retains with more or lefs energy thofe which are already in combination ; fo that it is impoflible to produce any change in nature, without interrupting or modifying this attractive power. It is natural, therefore, and even indifpenfable, that we fhould fpeak of the law of the affinities before we proceed to treat of the methods of analyfis. Affinity is exercifed either between principles of the fame na- ture, or between principles of a different nature. We may, therefore, diftinguifh two kinds of affinity, with re- fpect to the nature of bodies. 1. The affinity of aggregation, or that which' exifts between two principles of the fame nature. 2. The affinity of compofition, or that which retains two or more principles of different natures in a ftate of combination, OF THE AFFINITY OF AGGRF.GATION. Two drops of water which unite together into one, form an aggregate, of which each drop is known by the name of an inte- grant part. An aggregate differs from a.heap ; becaufe the integrant parts of this laft have no perceptible adhefion to each other ; as, for e?; am pie, a heap of barley, of fand, &c. 54 Affinity $f Compiifttisft. An aggregate and a heap differ from a mixture ; becaufe the conftituent parts of this laft are of a different nature ; as, for example, in gun-powder. The affinity of aggregation is ftronger, the nearer the inte- grant parts approach to each other ; fo that every thing which tends to feparate Or remove thefe integrant parts from each other, diminifhes their affinity, and weakens their force of cohefion. Heat produces this effect upon moft known bodies : hence it is that melted metals have no confiftence. The calorick, or matter of heat, by combining with bodies, almoft always pro- duces an effect oppofite to the force of' attraction ; and we might confider ourfelves as authorized to affirm that it is a prin- ciple of repulfion, if found chemiflry had not proved that it pro- duces this effect only by its endeavour to combine with bodies, and thereby neceffarily diminifh their force of aggregation, as all other chemical agents do. Befides which, the extreme levity of calorick produces the effect that, when it is combined with any given body, it continually tends to elevate it, and to over- come that force which retains it, and precipitates it towards the earth. The mechanical operations of pounding, of hammering, or of cutting, likewife diminifh the affinity of aggregation. They re- move the integrant parts to a diflance from each other ; and this new difpofition, by prefenting a lefs degree of adhefion, and a larger furface, facilitates the immediate action, and aug- ments the energy, of chemical agents. It is for this purpofe that bodies are divided when they arc to be analyfed, am! that the effect of re-agents is facilitated by the action Of heat. The mechanical divifion of bodies is more difficult, the ftrong- er their aggregation. Aggregates exift under different dates ; they are folid, liquid, aeriform, Sec.—See Fourcroy's Chemiflry. OF THE AFFINITY OF COMPOSITION. Bodies of different kinds exert a tendency or attraction upon each other, which is more or lefs ftrong ; and it is by virtue of this force that all the changes of compofition or decompofition obferved amongft them, are effected. The affinity of compofition exhibits invariable laws in all the phenomena it caufes. We may ftate thefe laws as gene*! principles ; to which may be referred all the effects prefented to our obfervation by the action of bodies upon each other. I. The affinity of compofition acts only between the conftit- uent parts cf bodies. Affinity of Compofition. 55 The general law of attraction is exerted upon the maffes - and in this refpect it differs from the law of the affinities whichjdoes not perceptibly act but on the elementary particles of bodies. Two bodies placed near each other do not unite j. but, if they be divided and mixed^ a combination may arife. We have examples of this when the muriate of foda, or com- mon fait, is triturated with lithrage j the muriate ammoniack, or common fal ammoniack, with lime, &c. And it may be af- ferted that the energy oi the affinity of compofition is almoft al- ways proportioned to the degree of the divifion of bodies. II. The affinity of compofition is in the inverfe ratio of the affinity of aggregation* It is fo much the more difficult to decompofe a body, as its conftituent principles are united or retained by a greater force. Gafes, and efpecially vapours, continually tend to combination, becaufe their aggregation is weak : and nature, which is con- ftantly renewing, the productions of this univerfe, never com- bines folid with folid ; but, reducing, every thing into the form of gas, by this means breaks the impediments of aggregation ; and thefe gafes uniting together, form folids in their turn. Hence, no doubt, it arifes, that the affinity of compofition is fo much the more ftrong as bodies approach nearer to the ele- mentary ftate ■, and we fhall obferve, on this fubject, that this law of nature is founded in wifdom : for if the force or affinity of compofition did not increafein proportion as bodies were brought to this degree of fimplicity ; if bodies did not affume a decided tendency to unite and combine, in proportion as they approach to their primitive or elementary ftate ; the mafs of elements would continually increafe by thefe fucceffive and uninterrupt- ed decompofitions; and we mould infenfibly return again to that chaos or confufion of principles, which is fuppofed to have been the original ftate of this globe. The neceflity of this ftate of divifion, which is fo proper to increafe the force of affinity, has caufed it to be admitted as an inconreftible principle, that the affinity of compofition does not take place, unlefs one of the bodies be in a fluid ftate : corpora tion agunt mfi fintfiuida. But it feerns to me that extreme di- vifion might be fubftituted inftead of diflblution ; for both thefe operations tend only to attenuate bodies, without altering their nature. It is by virtue of this divifion, which is equivalent to diflblution, that the decoinpofition of muriate of foda is effected by trituration with minium, as well as the union of cold and dry alkali with antimony, and the difengagement of volatile al- kali by the fimple mixture of fal ammoniack with lime. $6 Affinity of Compofition. III. When two or more bodies unite by the affinity of com- pofition, their temperature changes. This phenomenon cannot be explained but by confidering the fluid of heat as a conftituent principle of bodies, unequally dif- turbed amongft them \ fo that, when any change is produced in bodies, this fluid is difplaced in its turn, which neceffarily produces a change of temperature. We fhall return to thefe principles when we fpeak of heat. IV. The compound which refults from the combination of two bodies, poffeffes properties totally different from thofe of its conftituent principles. Some chemifts have affirmed, that the properties of com- pounds were intermediate between thofe of their conftituent parts. But this term " intermediate" has no meaning in the prefent cafe ; for what intermediate qualities can exift between four and fwect, or between water and fire ? If we attend ever fo little to the phenomena which are ex- hibited to us by bodies in their compofition, we fhall perceive that their form, their tafte, and their confidence, are changed in combination; and we cannot eftablifh any rule to indicate, a priori, all the changes which may arife, and the nature and properties of the body which fhall be formed. V. Every individual fubftance has its peculiar affinities with the various fubftances prefented to it. If all bodies had the fame degree of affinity with each other, no change could take place amongft them: we fhould not be able to difplace any principle by prcfenting one body to another. Nature has therefore wifely varied the affinities, and appointed to each body its relation with all thofe that can be prefented to it. It is in confequence of this difference in the affinities that all chemical decompofitions are effected : all the operations of na- ture and art are founded upon it. It is therefore of importance to be well acquainted with all the phenomena and circumftan- ces which this law of decompofition can prefent to us. The affinity of compofition has received different names, ac- cording to its effects. It is divided into fimple affinity, double affinity, the affinity of an intermedium, reciprocal affinity, &c. i. Two principles united together, and feparated by means of a third, afford an example of fimple affinity : it confifts in the difplacing of one principle by the addition of a third. Bergman has given it the name of Elective Attraction. The body which is difengaged, or difplaced, is known by the name of the Precipitate. An alkali precipitates metals from their folutions; the fulphurick acid precipitates the muriatick, the nitrick, &c. Laws of De.-unpifttion. Various Cafes of Affinity 57" The precipitate is not always formed by the difengaged fub- ftance. Sometimes the new compound itfelf is precipitated ; as, for example, when I pour the fulphurick or vitriolick acid on a folution of muriate of lime. Sometimes the difengaged body and the new compound are precipitated together ; as, for example, when the fulphate of magnefia or Epfom fait is diffolv- ed in water, and precipitated by means of lime-water. 2. It often happens that the compound of two principles cannot be deftroyed either by a third or a fourth body feparate- ly applied ; but if thefe two bodies be united, and placed in contact with the fame compound, a decompofition or change of principles will then take place. This phenomenon conftitutes the double affinity. An example will render this propofition more clear and precife. The fulphate of pot-afh or vitriolated tartar is not completely decomposed by the nitrick acid or by lime, when either of thefe principles is feparately prefented ; but, if the nitrick acid be combined with lime, this nitrate of lime will decompofe the fulphate of pot-afh. In this laft cafe the affinity of the fulphurick acid with the alkali is weakened by its affinity to the lime. This acid, therefore, is fubject to two attractions ; the one which retains it to the alkali, and the oth- er which attracts it towards the lime : Mr. Kirwan has named the firft the Quiefcent Affinity, and the other the Divellant Af- finity. The fame may be faid refpecting the affinities of the alkali; it is retained to the fulphurick acid by a fuperiour force, but neverthelefs attracted by the nitrick acid. Let us fuppofe, now, that the fulphurick acid adheres to the alkali with a force as 8, and to the lime by a force expreffed by the number 6 ; that the nitrick acid adheres to the lime by a force as 4, and tends to unite with the alkali by a force as 7. It may then be perceived that the nitrick acid and the lime, feparately applied to the fulphate of pot-alh, would not produce any change : but if they be prefented in a ftate of combination, then the fulphu- rick acid is attracted on the one hand by 6, and retained by 8 ; it has therefore an effective attraction to the alkali as 2. On the other hand, the nitrick acid is attracted by a force as 7, and retained by a force as 4 ; it therefore retains a tendency to unite with the alkali, which is denoted by the number 3.; and confe- quently it ought to difplace the fulphurick acid, which is retain- ed only by a force as a. 3. There are cafes in which two bodies, having no percepti- ble affinity to each other, obtain a difpofition to unite by the in- tervention of a third j and this is called the affinity of an inter- medium. An alkali is the intermedium of union between oil and water ; hence the theory of lix'.viums, of wafhings, &c.5cc. 58 Regular Figures of Bodies If the affinities of bodies were well known, we might foretel the refults of all operations : but it is obvious how difficult it muft be to acquire this extenfive knowledge of nature ; more efpecially fince modern difcoveries have exhibited to us an infin- ity of modifications in our proceffes, and have fhewn that re- fults may vary with fuch facility, that even the abfence or pref- ence of light will render them very different. As long as chemiflry was confined to the knowledge of a few fubftances, and was bufied only in attending to a certain num- ber of facts, it was poffible to draw up tables of affinity, and to exhibit the refult of our knowledge in one and the fame table. But all the principles upon which thefe tables have been.con- ftructed, have received modifications ; the number of principles has increafed; and we find ourfelves under the neceflity of la- bouring upon new ground. A fketch of this great work,may be feen in the Effay on Affinities of the celebrated Bergman, and in article Affinity in the Encyclopedic Methodique. VI. The particles which are brought together and united by affinity, whether they be of the fame nature or of different na- tures, continually tend to form bodies of a polyhedral, conflant, and determinate form. This beautiful law of nature/hy which fhe impreffes on all her productions a conflant and regular form, appears to have been unknown to the ancients : and when chemifts began to discov- er that almoft all bodies of the mineral kingdom affected regular forms, they at firft diftinguifhed them according to the inaccu- rate refemblance fuppofed to exift between them and other known bodies. Hence the denomination of cryftals in pyra- mids, needles, points of diamonds, croffes, fword blades, &c. We are more particularly indebted to the celebrated Linnaeus for the firft precife ideas of thefe geometrical figures. He took notice of the conftancy and uniformity of this character ; and this celebrated naturalifl thought himfelf authorized to make it the bafis of his method of claffification of the mineral kingdom. Mr. Rome de Lifle has proceeded ftill farther : he has Subject- ed all the forms to a ftrict examination : he has, as it were, de- compofed them ; and is of opinion that he can diftinguifh in the cryftals of all analogous or identical fubftances, the fimple modifications and fhades of a primitive form. By this means he has reduced all the confufed and irregular forms to certain primitive figures ; and has attributed to nature a plan or primi- tive defign, which fhe varies and modifies in a thoufand manners, according to circumftances that influence her proceedings. This truly great and philofophical work has rendered this part of mineralogy in the higheft degree interefting; and if we produced by Cryflallizatiott. 59 fhould admit that Mr. De Lifle has perhaps carried thefe refem- blances too far, we cannot but allow that he deferves a diftin- guifhed place amongft thofe authors who have contributed to the progrefs of fcience. The Cryftallographie of this celebrated naturalift may be perufed with advantage. The abbe Hauy has fince applied calculation to obfervation. He has undertaken to prove that each cryftal has a nucleus or primitive form ; and has fhewn the laws of diminution to which the component lamina; of the cryftals are fubject in their tranfition from the primitive to the Secondary forms. The de- velopement of thefe fine principles, and their application to pryftals the beft known, may be feen i& his theory of the ftruct- ure of cryftals, and in feveral of his memoirs printed in the vol- umes of the Academy of Sciences. The united labours of thefe celebrated naturalifts have carri- ied chryftallographyto a degree of perfection of which it did not appear fufceptible. But we fhall, at this moment, attend only to the .principles according to which cryftallization, is effedted. To difpofe a fubftance to cryftallization, it is neceffary in the firft place to reduce it to the moft complete ftate of divifion. This divifion may be effected by folution, or by an operation purely mechanical. Solution may be effected either by the means of water or of fire. The Solution of Salts is in general performed in the firft liquid, that of metals is effected by means of the fecond ; and their folution is not complete until a degree of heat is applied of fufficient intenfity to convert them into the ftate of gas. When the water which holds any fait in folution is evaporat- ed, the principles of the diffolved body are infenfibly brought nearer to each other, and it is obtained in regular form. The fame circumftance nearly takes place in the folution by fire. When a metal is impregnated with this fluid, it does not cryf- allize but in proportion as this excefs of igneous fluid is with- drawn. In order that the form of a cryftal may be regular, three cir- cumftances are required ; time, a fufficient fpace, and repofe. Confult Linnaeus, Daubenton, 8?c. A. Time caufes the fuperabundant fluid to be flowly diffipat- ed, and brings the integral parts nearer each other by infenfible gradation, and without any fudden fhock. Thefe integrant parts therefore unite according to their conflant laws, and form a regular cryftal. For this reafon it is, that flow evaporation is recommended by all good chemifts. Vide Stahl's Treatifc on Salts, chap. 29. 6a; Various Appearances In proportion as the evaporation of the folvent is effected, the principles of the diffolved body approach each other, and their affinity is contiually augmented while that of the folvent remains unaltered. Hence it arifes, no doubt, that the laft portions of the folvent are moft difficultly volatilized, and that falts retain a greater or lefs quantity, which forms their water of cryftalliza- tion. The proportion of water of cryftallization not only varies greatly in the different falts, but it adheres with greater or lefs Strength. There are fome which fuffer this water to fly off when they are expofed to the air; fuch as foda or the mineral alkali, the fulphate of foda or Glauber's fait, &c In this Situ- ation thefe falts lofe their tranfparency, and fall into powder: they are then faid to have effloreSced. There are other falts which obftinately retain their water of cryftallization ; fuch as the muriate of pot-alh, the nitrate of pot-afh or common nitre, &c. The phenomena prefented to us by the different falts, when forcibly deprived of their water of cryftallization, exhibit other varieties. Some crackle with the heat, and are thrown about in fmall pieces when the water is diffipated : this appearance is called decrepitation. Others emit the fame water in the form of fleam, and are liquefied with a diminution of their bulk. Others again Swell up, and become converted into a bliftered or porous fubftance. We are indebted to Mr. Kirwan for an accurate table of the water of cryftallization contained in each fait. This table may be feen by confulting his Mineralogy. t The fimple cooling of the fluid which holds the fait in folu- tion may precipitate a confiderable quantity. The calorick and the water diffolve a greater quantity of fait when their action is united'; and it may eafily be imagined that the Subtraction of one of the folvents muft occafion the precipitation of that por- tion which it held in folution. Thus it is that warm water Saturated with fait, muft fuffer a part to precipitate by cooling ; and for this reafon cryftallization always begins at the furfaceof the liquid, and on the fides of the containing veffel; namely, be- caufe theSe parts are the firft which Suffer refrigeration. It is the alteration of heat and cold which caufes the atmof- phere to diffolve fometimes a greater, and Sometimes a lefs quan- tity of v/ater ; and conftitutes mills, the evening dew, &c. The mutual approach of the conftituent parts of a body held in folution may be likewife accelerated by prefenting to the wa- ter which fufpends them, another body which has a ftronger af- finity to it. It is upon this principle that alcohol precipitates fev* eral falts. attending Cryftallization, cifV. 61 B. Space or fufficient room is likewife a condition neceffary for obtaining regular cryftallization. If nature be reftrained in her operations, the product of her labour will exhibit fymptoms of this ftate of conftraint. It may be afferted that nature forms her productions according to all the circumftances which may influence her operations. C. A ftate of repofe in the fluid is likewife neceffary to obtain very regular forms. Uninterrupted agitation oppofes all Sym- metrical arrangement ; and in this caSe the cryftallization obtain- ed will be conSuSed and indeterminate. I am perSuaded that, in order to obtain bodies under the form of cryftals, a previous folution is not neceffary, but that a fimple mechanical divifion would be fufficient. To obtain a conviction of this truth, it is only neceffary to obferve that folution does not change the nature of bodies, but fimply procures an extreme ftate of divifion ; fo that the difunited principles approaching each other very gradually, and without ftarts, can adapt them- felves to each other, by following the invariable laws of their gravity and affinity. Now a divifion purely mechanical produces the fame effect, and places the principles in the fame difpofi- tion. We ought not therefore to be Surprized if moft Salts, Such as gypSum, when diSperSed in the earth, fhould affume reg- ular forms without any previous folution ; neither ought we to think it ftrange if the imperceptible fragments of quartz, of fpar, &c. when carried along and prodigioufly divided by theac- tion of waters, fhould be depofited in the form of regular cryftals. A very Angular property may be obferved in falts ; which may be referred to cryftallization, but is likewife in fome meafure remote Srom it, becauSe it does not depend upon the Same caufes. This is the property of rifing along the fides of the vef- fels which contain the folution. It is known by the name of Saline Vegetation. I have firft demonftrated that this phenomena depends on the concurrence of air and light ; and that the effect may be deter- mined at pleafure towards any part of the veffel, by managing and directing the action of thefe two agents. I have fliewn the principal forms which this Singular vegeta- tion affects. The detail of my experiments may be feen in the third volume of the Memoirs of the Academy of Touloufe. Mr. Dorthes has confirmed my refults; and has moreover obferved that camphor, fpirits of wine, water, &c. which rife by infenfible evaporation in half-filled veflels, conftantly attach themfelves to the molt enlightened parts of the veffels. Mefl'rs. Petit and Rouelle have treated on the vegetation of falts ; but a leries of experiments on the fubject was wanting. T!i!ti is what we have endeavoured to Supply. 62 Methods of feparaling the component Parts of JBcdies. SECTION II. Concerning the various Means employed by Chemifts to overcome the Adhefion which exifts between the Particles of Bodies. ± HE law of affinities, towards which our attention has been directed, tends continually to bring the particles of body into contact, and to maintain them in their ftate of union. The efforts of the chemift are almoft all directed to overcome this attractive power, and the means he employs are reducible to—• i. The divifion of bodies by mechanical operations. 2. The divifion or Separation of the particles from each other by the af- fiftance of Solvents. 3. The means of presenting to the Several principles of the Same bodies, Subftances which have a Stronger affinity to them than thoSe principles have to each other. I. The different operations performed upon bodies by the chemift, to determine their nature, alter their form, their tex- ture, and even in fome inftances change their conftitutiqn. All thefe changes are either mechanical or chemical. The mechanical operations we fhall at prefent deScribe, do not change the nature of Subftances, but in general change only their form and bulk. Thefe operations are performed by the hammer, the knife, the peftle, &c. Whence it follows, that the chemical laboratory ought to be provided with all thefe in- struments. Thefe divisions or triturations are performed in mortars of ftone, of glafs, or of metal. It is the nature of the fubftance un- der examination which determines the uSe of one or the other of thefe veflels. The object of this preliminary operation is, to prepare and diSpoSe bodies for new operations which may difunite their prin- ciples and change their nature ; thefe laft-mentioned operations, which may be distinguished by the appellation Chemical, are what moft effentially conftitute the analyfis. II. The folution to which we are at preSent to attend, confifts in the divifion and disappearance of a folid in a liquid, but with-. out any alteration in the nature of the body fo diffolved. The liquid in which the folid difappears, is called the folvent or menftruum. The agent of folution appears to follow certain conflant laws, which wc fhall here point out. Phenomena of Solution, 63 A. The agent of Solution does not appear to differ from that of affinity ; and in all caSes the folution is more or lefs abundant, the greater the affinity of the integrant parts of the folvent is td thoSe of the body to be diffolved* From this principle it follows, that, to facilitate folution, it is neceffary that bodies fhould be triturated and divided. By this means a greater number of furfaces are prefented, and the affini- ty of the integrant parts is diminifhed. It fometimes happens that the affinity between the folvent and the body prefented to it has fo little energy, that it does not become perceptible till after a confiderable interval of time. Thefe flow operations of which we have fome examples in out laboratories, are common in the works of nature ; and it is probably to Similar caufes that we ought to refer moft of thofe refults whoSe cauSes or agents efcape our perception or observa- tion. B. Solution is more Speedy in proportion as the body to be diffolved preSents a greater SurSace : on this principle is founded the practice of pounding, triturating, and dividing bodies intend- ed to be diffolved. Bergman has even obferved, that bodies which are not attacked in confiderable maffes, become foluble after minute divifion. Letters on Iceland, p. 421.* C. The folution of a body conftantly produces cold. Ad- vantage has ever been taken of this phenomenon to procure arti- ficial cold, much fuperiour to the moft rigorous temperature ever obferved in our climates. We fhall again advert to this princi- ple when we come to treat of the laws of heat. The principal Solvents employed in our operations are water, alcohol, and fire. Bodies Submitted to one or the other of theSe Solvents preSent Similar phenomena ; they are divided, rarefied, and at laft difappear ; the moft refractory metal melts, is dif- fipated in vapour, and paffcs to the ftate of gas, if a very ftrong heat be applied to it. This laft ftate forms a complete folution of the metallick fubftance in the calorick. The effect of calorick is often-united with one of the other folvents, to accomplifh a more fpeedy and abundant folution. The three folvents here mentioned do not exercife an equal action on all bodies indiscriminately. Skilful chemifts have ex- hibited tables of the diffolving power of thefe menftruums. We may fee, in the mineralogy of Kirwan, with what care that cel- ebrated chemift has exhibited the degree of folubility of each fait in water. The table of Mr. De Morveau may likewife be * Von Tr»ilY Letters, quoted by Mr. Bergman. T. 64 EffeBs of Re-Agents. confulted on the diffolving power of alcohol. Journal de Phy- fique, 1785. Moft authors who have treated of folution have confidered it in too mechanical a point of view. Some have fuppofed fheathfl in the folvent, and points in the body diffolved. This abfurd and gratuitous Supposition has appeared Sufficient to account for the action of acids upon bodies. Newton and Gaffendi have admitted pores in water, in which falts might infinuate them- felves ; and have by this means explained why water does not augment in its bulk in proportion to the quantity of fait it takes up. Geffendi has even fuppoSed pores of different Sorms ; and has endeavoured to Shew by this means how water Saturated with one Salt may diffolve others of another kind. Dr. Wat Son', who has obServed the phenomena of folution with the greateft care, has concluded from his numerous experiments ; 1. That the water rifes in the veffel at the moment of the immerfion of the fait. 2. That it falls during the folution. 3. That itriSes after the folution above the original level. . The two laft effects feem to me to ariSe from the change of temperature which the liquor undergoes. The refrigeration arifing from the folution muft diminifh the volume of the folvent; but it ought to return to its firft ftate as foon as the diflblution is finifhetl. The tables of Dr. Watfon refpecting theSe phenomena, and the fpecifick gravity of water faturated with different falts, may, be confulted in the Journal de Phyfique, vol. xiii. p. 62* III. As the peculiar affinities of bodies to each other are vari- ous, the conftituent principles may be eafily difengaged by other fubftances ; and it is upon this consideration that the action of all the re-agents employed by chemiflry in its analyfis is found- ed. Sometimes the chemift difplaces certain* principles, which he can in that ftate examine more accurately, becaufe infulated, and difengaged from all their combinations. It frequently hap- pens that the re-agent made ufe of combines with fome princi- ple of the body analyfed ; and a compound arifes, whofe.char- acters indicate to us the nature of the principle which has thus entered into combination, becaufe the combinations of the prin- cipal re-agents, with various bafes are well known. It likewife frequently happens that the re-agent made ufe of is itSelS decom- posed, which circumftance renders the phenomena and the products more complicated ; but we are enabled from the na- ture of thefe products to form a judgment of the component parts of the body analyfed. This laft fact was little attended to by the ancient chemifts ; and this is one of the principal defects » Or in the fifth vol. of his Chemical Eflav.. T. Method of Studying the Science of Chemiflry. 6 J of the labours of Stahl, who has referred moft of thofe phenom- ena to the bodies which he fubmitted to analyfis, which in re- ality arofe only from the decompofition of the re-agents employ- ed in his operations. SECTION III. Concerning the Method of Proceeding which the Chemift ought to fol- • low in the Study of the various Bodies prefented to us by Nature. L HE progrefs made in any fcience depends upon the folidity of thofe principles which form its bafis and upon the method of Studying them. It is not, therefore, to be wondered at, that chemiflry made but little progrefs, in thoSe times, when the language of chemifts was enigmatical, and when the princi- ples of the fcience were founded only on analogies falfely de- duced, or on a few facts illy understood. In the times which have followed this epocha, the facts have indeed been more at- tended to ; but, inftead of fuffering them to fpeak for themfelves chemifts have been defirous of making applications, drawing confequences, and eftablifhing theories. Thus it was that Stahl, when he firft obServed that oil of vitriol and charcoal produced fulphur, if he had then confined himfelf to the fimple relation of the fact, he would have announced a valuable and eternal truth ; but when he concluded that the Sulphur" was produced by the combination of the inflammable principle of the charcoal with the oil of vitriol, he afferted that which the experiment does not point out : then it was that he proceeded further than the facts warranted ; and this firft rafh ftep might be a firft ftep towards errour. All doctrine, in order to be lafting, ought to confift of the pure and fimple expreffion of facts : but we are almoft al- ways governed by our imaginations ; we adapt the facts to our manner of feeing them, and thus we are milled by ourfelves. The prejudice of felf-love afterwards furnifhes us with various means to avoid recantation ; we exert ourfelves to draw our fucceffors into the.fame paths of errour ; and it is not till after much time has been loft, after many vain conjectures have been exhibited, and after we have the ftrongeft convictions that it is impoffible to bend the nature of things to our caprices and un- 66 Method of Studying founded ideas, that fome fuperiour mind difengages itfelf from the/iclufion ; and returning to experiment, and the nature of things, Suffers himfelf to be led no further than he is authorized by thefe to proceed. We may affirm, to the honour of our contemporaries, that facts are at prefent difcuffed by a much feverer logick ; and it is to this vigorous method of inveftigation and difcuffion that we are indebted for the rapid progrefs of chemiflry. It is in con- fequence of this dialeclick march that we have at length arrived to the practice of attending to all the principles which are com- bined or difengaged in the operations of nature and art. We keep an account of all the circumftances which have a more or lefs confiderable influence on the refults, and we deduce fimple and natural confequences from the whole of the facts; by which means we create a fcience as Strict: in its principles as fublime in its applications. This then is the moment to draw out a faithful fketch of the actual ftate of chemiflry, and to collect in the numerous writ- ings of modern chemifts every thing which may ferve to lay the foundation of this beautiful fcience. Not many years ago, it was poffible to prefent, in a few words, the whole of our knowledge of chemiflry. It was fuf- ficient at that time, to point out the methods of performing pharmaceutical operations ; the proceffes of the arts were almoft all enveloped in darknefs, the phenomena of nature were all enigmatical ; and it is only fince this ve,il has begun to be re- moved that we have beheld the developement of a collection of facts and refearches referable to general principles, and forming a fcience entirely new. Then it was that a number of men of genius reviewed the whole, and attended to the improvement of chemical knowledge. Every ftep in their progrefs brought them nearer to the truth ; and in a few years we have beheld a perfpicuous doctrine arife out of the ancient chaos. Every event l^as appeared conformable to the laws they eftablifhed ; and the phenomena of art and nature are now explained with equal facility. But in order to advance with fpeed in the career which has been thus opened, it is neceffary to explain certain principles, according to which we may direct our fteps. in the firft place, I think it proper to avoid that tedious cuf- • torn which fubjects the beginner in any fcience to the painful talk of collecting all the opinions of various philofophers before he decides for himfelf. In reality, facts belong to all times, and are as unchangeable as nature herfelf, whofe language they are. Bat the confluences deduced from them muft vary according the Science of Chemiflry. *7 to the ftate of our acquired knowledge. It is eternally true for example, that the combuftion of fulphur affords the fulphurick acid. It was believed, for a certain time, that this acid was contained in the fulphur ; but our difcoveries on the combuf- tion of bodies ought to have led us to the deduction of a very different theory from that which prefented itfelf to the earlieft chemifls. We ought, therefore, to attach ourfelves principally *to facts; or rather we ought to attach ourfelves to the facts only, becaufe the explanation which is given of them at remote times is very feldom fuited to the preSent ftate of our knowledge. The numerous facts with which chemiflry has been fuccef- fively enriched, Sorm the firft embarraffment of the ftudent who is defirous of acquiring the elements of this Science. In fact, what are the elements of a fcience ? The clear, fimple, and ac- curate enunciation of thofe truths which form its bafis. It is neceffary, therefore, for the full accomplishment of this purpofe, to analyfe all the facts, and to exhibit a faithful and clear abridg- ment : but this method is impracticable on account of the nu- merous details, and the infinite number of difcufiions, into which it would lead us. The only proceeding, therefore, which appears to me to be practicable, is to exhibit the moft decifive experiments, thofe which are the leaft contefted, and to neglect thofe which are doubtful or inconclufive : for one experiment, well made, eftablifhes a truth as inconteftibly as a thoufand equally averred. When a propofition is found to be Supported by fufpicious or contefted facts, when oppofite theories are built upon contra- dictory experiments, we muft have the courage to difcufs them, to repeat them, and to acquire a certainty of the truth by our own endeavours. But when this method of conviction is out of our power, we ought to weigh the degree of confidence which the defenders of the oppofite facts are entitled to ; to examine whether analagous facts do not lead us to adopt certain refults j after which it becomes us to give our opinion with that modefty and circumfpection, Suitable to the greater or leSs de- gree of probability annexed to each opinion. But-vyhen any doctrine appears to us to be eftablifhed on ex- periments of fufficient validity, it then remains to be applied to the phenomena of nature and art. This, in my opinion, i*s the molt certain touchftone to diftinguifh true principles from thofe which are without foundation. And when I obferve that all the phenomena of nature unite, and conform themfelves, as it were, to any theory, I conclude that this theory is the cxpreffion and the language of truth. When, for example, I behold that a 6*8 Method of Studying plant can be fupported by pure water alone, that metafs are ca>- cinable, that acids are formed in the bowels of the earth, have I not a right to conclude that the water is decompofed ? and do not the chemical facts which in our laboratories afford a teftimo- ny of its decompofition—do not thefe acquire a new force by the obfervation of the preceding phenomena ? I conclude, there- fore, that we ought to make a point of uniting thefe two kinds of proofs ; and a principle deduced from experiment is not, in my opinion, demonstrable, until I fee that it may with facility be applied to the phenomena of art and nature. Hence, if I find myfelf in a ftate of hesitation between oppofite fyftems, I will decide in favour of that whofe principles and experiments adapt themfelves naturally, and without force to the greateft number of phenomena. I will always diftruft a fingle fact, which is applicable to no conclufion ; and I will confider it as falfe, if it be in oppofition to the.phenomena which nature prefents to us. It appears to me *likewife that he who profeffes to ftudy, or even to teach chemiflry, ought not to endeavour to arrive at or exhibit the whole which has been done in each department, or to follow the tedious progrefs of the human mind from the ori- gin of a difcovery to the prefent time. This faftidious erudi- tion is fatiguing to the learner ; and thefe digreffions ought in no caSe to be admitted in the enunciation of fcience, excepting when the historical details afford interefting facts; or lead us by uninterrupted degrees to the prefent ftate of our knowledge. It rarely happens, however, that this kind of refearches, this gen- ealogy of fcience, affords us fuch characters; and it ought no more to be admitted, in general, that an elementary writer fhould bring together and diScuSs every thing which has been done in a Science, than that he who undertakes to direct a trav- eller Should previoufly enter into a long differtation on all the roads which have been Successively made, and on thoSe which ftUl exift, before he fhould point out the beft and fhorteft way to arrive at the end of his journey. It may, perhaps, be faid of the hiflory of fcience, and more efpecially that oS chemiflry, that it reSembles the hiftories oS nations. It Seldom affords any light reSpecting the preSent Situation of affairs; exhibjis many fables concerning paft times ; induces a neceflity of entering into difcuffions upon the circumftances that paSs in review ; and fuppoSes a maSs oS extraneous knowledge acquired on the part of the reader, which is independent of the purpofe aimed at in the ftudy of the elements of chemiflry. When thefe general principles, reSpecting the Study of chem- iflry, are once well eftablifhed, we may aSterwards proceed in the chemical examination of bodies in two ways ; we may either fhe Science of Chemiflry. fy proceed from the fimple to the compound, or we may defcend from the compound to the fimple. Both thefe methods have their inconvencies ; but the greateft, no doubt, which is found in following the firft method is, that, by beginning with the fim- i)left bodies, we prefent fubftances to the consideration of the earner which nature very Seldom exhibits in Such a ftate of na- kednefs and Simplicity ; and we are forced to conceal the feries ©f operations which have been employed to diveft thefe fubftan- ces from their combinations, and reduce them to the elementary ftate. On the other hand, if we prefent bodies to the view of the learner fuch as they are, it is difficult to fucceed in an accu- rate knowledge oS them ; becauSe their mutual action, and in general moft of their phenomepa, cannot be underftood without the previous and accurate knowledge of their conftituent prin- ples, fince it is upon thefe alone that they depend. After having maturely confidered the advantages and incon- veniences of each method, we give the preference to the firft., We Shall therefore begin by giving an account of the feveral bod- * ies in their moft elementary ftate, or reduce to that term beyond Which analyfis can effect nothing ; and, when we Shall have explained their various properties, we will combine thefe bodies with each other, which will afford aclafsof fimple compounds : and hence we fhall rife by degrees to the knowledge of bodies, and the moft complicated phenomena. We fhall be careful, in any examination of the feveral bodies to which we fhall d rect our refearches, to proceed from known to unknown ; and our firft attention fhall be directed to the elementary, fubftances. But as it is impoffible, at one and the fame time, to treat of 911 thofe fubftances, which the prefent ftate of our knowledge obliges us to confider as elementary, we fhall confine ourfelves tQ the exhibition of fuch as are of the greateft importance in the phenomena of the globe we inhabit, Such as are almoft univer- fally fpread over its furface, and fuch as enter as principles into the compofition of the re-agents moft frequently employed in our operations ; fuch, in a word, as we continually find in the examination and analyfis of the component parts of the globe. Light, heat, fulphur, and carbone are of this number. Light modifies all our operations, and moft powerfully contributes to the production of all the phenomena which appertain to bodies either living or inanimate. Heat, distributed after an unequal proportion among all the bodies of this univerfe, eftablifhes their various degrees of confiftence and fixity ; and is one of the great means which art and nature employ to divide and vola- tilize bodies, to weaken their force or adhefion, and by that means prepare them for analyfis. Sulphur exifts in the products *]to Simple or Elementary Subftances, of the three kingdoms; it forms the radical of one of the bcft known, and moft generally employed, acids; it exhibits inter- efting combinations with moft fimple Subftances ; and under thefe feveral points of view, it is one of the fubftances the moft neceffary to be known in the firft fteps of chemical fcience. The fame may befaid of carbone ; it is the moft abundant fixed product found in vegetables and animals. Analyfis has discov- ered it in fome mineral fubftances. Its combination with oxi- gene is fo common in bodies, and in the operations of art and nature, that there are Scarcely any phenomena which do not pre- fent it to our view, and which confequently require the knowl- edge of its properties. From all thefe reafons it appears to us, that for the advancement of chemiftry it is neceffary our firft proceeding Should be founded on the knowledge of thefe fub- ftances ; and that we fhould not direct our attention to other fimple or elementary fubftances, accordingly as they prefent themfelves. SECTION IV. Concerning Simple or Elementary Subftances* -IF we call an eye over the fyftems which have been fucceffively formed by philofophers relative to the number* and nature of the elements, we fhall be aftonifhed at the prodigious variety which prevails in their manner of thinking. In the earlieft times, every one feems to have taken his own imagina- tion for his guide ; and we find no reafonable fyftem until the time when Ariitotle and Empedocles acknowledged as elements, Air, Water, Earth, and Fire. Their opinion has been well re- ceived for many ages ; and it must be confeffed that it is calcu- lated to Seduce the mind. There are, in fact, enormous maff- es, and inexhauftible Stores, that preSent themfelves to our view of thefe four principles, to which the deftruction or decompo- fition of bodies appeared to refer all the feveral component parts which formation or creation had taken from them. The author- ity of all thofe great men who had adopted this fyftem, and the analyfis of bodies which prefented only thefe four principles, afforded fufficient grounds for admitting this doctrine. Fire, or Heat. 7* But as foon as chemiftry had advanced fo far as to difcover the principles of bodies, the profeffors of that fcience prefumed to mark the number, nature, and character of the elements'; and every fubftance that was unalterable by the chemical meth- ods of decompofition, was confidered by them as a fimple or elementary principle. By thus taking the limits of analyfis as the term for indicating the elements, the number and the nature of thefe muft vary according to the revolutions and the progrefs oS chemiftry. This has accordingly happened, as may be Seen by confulting all the authors who have written on this fubject, from the time of Paracelfus to the preSent day. But it muft be confeffed that it is no fmall degree of rafhnefs, to afl'ume the extent of the power of the artift as a limit for that of the Creator, and to imagine that the ftate of our acquisitions is a ftate of per- fect knowledge. The denomination of Elements ought therefore to be effaced from a chemical nomenclature, or at leaft it Ought not to be u- fed but as an expreffion denoting the laft term of our analytical reSults -, and it is always in this SenSe that we Shall uSe the word. CHAPTER I, Concerning Fire. THE principal agent employed by nature to balance the pow- er and natural effect oS attraction, is fire. By the natural effect oS attraction we Should poffeSs none but folid and compact bod-» ies ; but the calorick unequally difperSed in bpdies tends incef- Santly to deftroy this adhefion oS the particles; and it is to this principle that we are indebted for the varieties of confiftence un- der which bodies prefent themfelves to our obfervation. The various fubftances that compoSe this univerSe are thereSore Sub- jected, on the one hand, to a general law which tends to bring them together ; and, on the other hand, to a powerSul agent which tends to remove them Srom each other : it is upon the respective energy oS theSe two forces that the confiftence of all bodies depends. When the affinity prevails, they are in. the Solid»ftatc ; when the calorick is moft powerful, they are in the ftate of gas ; and the liquid ftate appears to be tlu point of the equilibrium between thefe two powers. it is therefore effenrially neceffary to treat of fire, fince it acte Id leading a part in this univerfe ; and becaufe it is impoffible to treat of any fubftance whatever; without attending to the in- fluence of this a^'ent. 7 a Fire. Heat. Light, There are two things to be confidered in fire—heat and light. Thefe two principles, which have been very often confound- ed, appear to be very diftindt in their own nature; becaufe they are fcarcely ever proportional to each other, and becaufe each can exift without the other. The moft uSual acceptation of the word Fire comprehends heat and light; and its principal phenomena muft have been known for a long time. The diScovery of fire muft have been nearly as ancient as the human fpecies upon this globe. The fhock of two flints, the action of meteors, or the effect of volca- noes, muft have afforded the earlieft idea of it ; and it is, very aftonifhing that the inhabitants of the Marian Iflands were not acquainted with its effects before the invafion of the Spaniards. Thefe iflanders, who became acquainted with this terrible ele- ment only in confequence of its ravages, confidered it at firft as a malevolent being which attached itSelf to all beings, and devour- ed them.—See the Abbe Raynafs Hiftoire Philofophique, &c. The effects of fire are perhaps the moft aftonifhing of any which nature exhibits ; and we ought not to be furprized that the ancients confidered it as an intermediate being between fpirit and matter, and have built the beautiful fable of Prome- theus upon its origin. We have had the happinefs, in our time, to acquire well-founded and extenfive ideas refpecting this a^nt, which we fhall proceed to develope in the two fol- lowing articles. ARTICLE I. Concerning Calorick and Heat. When a metal or a liquid is heated, thefe bodies are dilated in every direction, are reduced to vapour, and at laft become ihvifible when the moft powerful heat is applied to them. Bodies which poffefs the principle of heat, part with it more or leSs readily. If we attentively obServe a body during its cooling, a flight movement of undulation will be perceived in the Surrounding air ; an effect which may be compared to the phenomenon exhibited upon the mixture of two liquors of une- qual denfity and weight. • It is difficult to conceive this phenomenon without admitting of a peculiar fluid, which panes firft from the body which heats to that which is heated, combines with the latter, produces the effects we have fpoken of, and afterwards efcapes to unite with other bodies, according to its affinities, and the law of equilib- rium, to which all bodies tend. General Properties of Heat. 73 This fluid of heat, which we fall Calorick, is contained in greater or lefs quantities in bodies, according to the greater or lefs degrees of affinity exifting between it and them. Various means may be employed to difplace or difengage the calorick. The firft is by the method of affinities : for example, water poured upon the fulphurick acid expels the heat, and takes its place ; and while there is a difengagement of heat, the Volume of the mixture does not increafe in proportion to the bulk of the two fubftances mixed. This fhews that penetration takes place, which cannot be explained but by admitting that the integrant parts of the water take the place of the calorick, in proportion as it is diffipated.—The fecond method of precip- itating calorick, is by friction and compreffion. In this cafe it is expreffed or fqueezed out, in the fame manner as water from a fpunge. In reality, the whole of the heat which may be pro- duced by friction, is not afforded by the body itfelf j becaufe, in proportion as the interiour heat is developed, the external air acts upon the body, calcines or inflames it, and itfelf gives out heat during its fixation. Fermentation, and in general every operation which changes the nature of bodies, may difengage calorick, becaufe the new compound may demand and receive a greater or lefs quantity. Hence it is that chemical operations produce fometimes cold, and fometimes heat. Let us now examine the form under which calorick prefents itielf. This fluid is difengaged either in a ftate of liberty, or in a ftate pf combination. In the firft cafe, the calorick always endeavours to obtain an equilibrium ; not that it is diftributed equally among all bodies, but it is diSperSed among them according to the degrees of its affinity. Whence it follows, that the circumambient bodies re- ceive and retain a quantity more or lefs confiderable. Metals are eafily penetrated by this fluid, and tranfmit it with equal facility ; wood and animal Subftances receive it to the degree oS combuftion j liquids, until they are reduced to vapour. Ice alone abSorbs all the heat communicated to it, without giving it out to other bodies until it has acquired the fluid ftate*. The degree of heat can be appreciated only by its effects -. and the inftruments which have been fucceffively invented to calcu- late it, and are known by the name of thermometers, pyrome- ters, &c. have been applied to the ftrict determination of the * The ingenious author has inadvertently been guilty of an overfight. Not orrty ice, but all other bodies, abforb heat, daring liquefaction, at he himfell thews hereafter, T. K 74 Admeafurement of Heat. feveral phenomena exhibited in confequence of the abforptioii of calorick in various bodies. The dilatation of fluids or of metals in the fluid ftate, by the feveral degrees of heat, has been long meafured by thermome- ters formed of glafs ; but this very fufible fubftance can only be ufed to aScertain degrees of heat inferiour to that which ren- ders the glafs itSelf fluid. Several means have been fucceffively propofed for calculating the higher degrees of heat. Mr. Leidenfroft has proved that the hotter a metal is, the more flowly will drops of water evap- orate from its Surface •, and he has propofed this principle for the construction of pyrometers. A drop of water in an iron fpoon, heated to the degree of boiling water, evaporates in one fecond -, a fimilar dropi poured on melted lead, is diffipated in fix or Seven Seconds ; and upon red hot iron in thirty. Mr. Ziegler, in his Specimen de dlgeftore Papini, has found that 80, Seconds were required to evaporate a drop of water at 5 20 degrees of Fahrenheit; and that one fecond is fufficient at the 300th de- gree. This phenomenon, which is more interefting to chemifty than pyrometry, to which it will always afford refults little fuf- ceptible of rigorous caculatiort, appears to me to depend upon the adhefion and decompofition of the water upon the metal. The moft accurate pyrometer we are acquainted with, is that which was prefented to the Royal Society of London by Mr. Wedgwood. It is constructed upon the principle, that the pureft clay Shrinks in the fire in proportion to the heat applied to it. This pyrometer confifts of two parts; one called the gauge, which ferves to meafure the degrees of diminution or Shrinking ; the other contains the fimple pieces of pure clay, which are called thermometer pieces. The gauge is formed of a plate of baked earth, upon' which are applied two rulers or ftraight pieces of the fame fubftance: TheSe rulers, being perfectly ftraight and even, are placed at the diftance of half an inqh from each other at one of their ends, and three tenths of an inch at the other. For greater conven- ience the gauge is divided into two parts, and the two'pieces are placed endways when required to be ufed. The length'of this rule is divided into 240 equal parts,of which each reprefents one tenth of an inch.* To form the thermometer pieces, the earth is fifted with the greateft attention, after which it is mixed with water, and the patte thruft through an iron tube, which gives it a cylindrical form, to be cut afterwards into pieces of a proper »This is in fact, the twelve-hundr:dthof an in.ch in th: width according t Thefe various thermometers are not applicable to all cafes. We cannot, for example, calculate with ftrictnefs the heat which efcapes from living bodies, or determine with precifion the temperature of any fubftance. But Meffrs. De la Place and Lavoifier (Acad, des Sciences, 1780) have invented an ap- paratus which appears to leave nothing Surther to be defired. It is constructed upon the principle that ice abSorbs all the heat communicated to it, without communicating it to other bodies until the whole is melted; So that Srom hence we may calculate the degrees oS heat communicated, by the quantity oS ice which is melted. It was neceffary, in order to afford ftrict reSults, to difcover the means of caufing the ice to abSorb all the heat diC: Pyrometor Thermometer of Wedgwood. of Fahrenheit. O IO77 ai 185 7 27 45§7 28 4H7 3"" 5137 90 H//7 9^ 1342 7 **5 1*327 *3° r7977 160 21877 7 6 The Calorimeter of engaged from the bodies under examination, and to cover it from the action of every other fubftance which might facilitate its fufion ; and, laftly, to collect with great care the water pro- duced by the fufion. The apparatus constructed by theSe two celebrated academi- cians for this purpofe, confifts of three circular veffels nearly in- scribed in each other; fo that three capacities are produced. The interiour fpace or capacity is formed by an iron grating, upon fupports of the Same metal, Here it is that the bodies fubjected to experiment are placed. The upper part of this cavity is clofed $y means oS a cover. The middle fpace, next to this, is defigned to contain the ice which Surrounds the inte- riour compartment. This ice is Supported and retained by a grate, upon which a cloth is Spread. In proportion as the ice melts, the water flows through the grate and cloth, and is col- lected in a veffel placed beneath. Laftly, the external Space o* compartment of the apparatus contains ice intended to prevent the effect of the external heat of the atmofphere. To ufe this excellent machine, the middle or Second fpace is filled wijh pounded ice, as. is likewife the cover of the internal fphere j the fame thing is done with regard to the external Space, as well as to the general covering of the whole machine : the interiour ice is Suffered to drain; and, when it ceaSes to afford water the covering of the internal fpace is raifed, to introduce the body upon which the experiment is intended to be made. Immediately after this introduction, the covering is put on, and the whole apparatus remains untouched until the included body has acquired the temperature of o, or the freezing temperature of water; which is the common temperature of the internal ca- pacity. The quantity of water afforded by the melting of the ice is then weighed ; arid this is an accurate meafure oS the heat diSengaged Srom the body, becauSe the fufion of the ice is the effect of this heat only. Experiments of this kind laft fifteen, eighteen, or twenty hours. It is of great confequence, that in this machine there Should be no communication between the middle, or fecond, and the external Space. It is likewiSe neceffary that the air oS the apartment Should not be lower than o, becauSe the interiour ice would then receive a degree of cold lower than that temperature. Specifick heat is merely the proportional quantity of heat neceffary to raife bodies of equal mafs to the fame number of degrees oS temperature ; So that, when the Specifick heat of a ( Solid body is required, its temperature muft be elevated a cer- tain number of degrees, at which inftant it muft be placed in, Lavoifter and De la Place. 77 the internal Sphere, and there left until its temperature is reduc- ed to o. The water is then colleaed, and this quantity divided by tlie product of the mafs of the body; and the number of degrees of its original temperature above o, will be proportional to its fpecifick heat. With regard to fluids, they are inclofed in veffels whofe heat has been previoufly determined. The operation is then the fame as for-fplids : excepting that the quantity of water afforded must be diminished by a deduction of that quantity which has been melted by the heat of the veffel. If it be required to determine the heat which is difengaged during the combination of various fubftances, they muft be all reduced, as well as their containing veffels, to the temperature of o. The mixture muft then be placed in the internal fphere ;• and the quantity of water collected is the meafure of the difen- gaged heat. In order to determine the heat of combuftion and refpiration, as the renewal of air is indifpenfable in thefe two operations, it is neceffary to eftablifh a communication between the internal part of the fphere and the furrounding atmofphere; and in order that the introduction of frefh air may not caufe any perceptible errour, thefe experiments ought to be made at a temperature little differ- ing from o, or at leaft the air which is introduced muft previ- oufly be brought to this temperature. To determine the fpecifick heat of any gas, it is neceffary to eftablifh a current through the internal part of the Sphere, and fo place two thermometers, one at the place of introduction, and the other at the place of efcape. By comparifon of the temperatures exhibited by thefe two inftruments, a judgment is formed of the heat abforbed, and the melted ice is meafured. An excellent memoir of Meffrs. De la Place and Lavoifier may be conSulted for the refults of the experiments they have made. The prefent extract contains only a fhort account of their valuable labours. The various means made ufe of for the admeafurement of heat, are founded on the general principle, that different bodies abforb heat in greater or lefs quantities. If this fact were not generally admitted, it might be eftablifhed on the three follow- ing facts. Dr. Franklin having expofed two fmall pieces of cloth, of the fame texture but of different colours, upon the fur- face of fnow, perceived, a few hours afterwards, that the red cloth was buritd in the fnow, while the other which was white had not fuffered any depreffion.* M. de Sauflure obferves. that * They were expo ft J t& die rays of the fun. T. 7$ General Properties of Heat. the peafants of the mountains of Switzerland are careful to Spread a black earth over the furface of grounds • covered with fnow, when they are defirous of melting it, to Sow their Seed. So likewife children burn a black hat in the focus of a Small lens which would Scarcely heat a white one. Such nearly are the phenomena of heat when it is difengaged in a ftate of liberty. Let us now contemplate thofe which it prefents when it efcapes from a ftate of combination. Heat is fometimes difengaged in a ftate of fimple mixture, as in the phenomena of vapours, Sublimations, &c. If heat be . applied to water, thefe two fluids will unite, and the mixture will be diffipated in the atmofphere ; but it would be an abuSe of words to call So weak an union by the name of combination : for, as Soon as the heat becomes in a fituation to combine with other bodies, it abandons the water, which returns to a liquid Slate. This body> during evaporation, continually carries with it a portion of heat ; and hence, perhaps, refult the advantages of tranfpiration, perfpiration, &c. But heat very frequently contracts a true chemical union with the bodies which it volatilizes: this combination is even fo per- fect, that the heat is not perceptible, but is neutralized by the body with which it is combined. It is then called latent heat, calor latens. The feveral cafes in which heat enters into combination, and paffes to the ftate of latent heat, may be reduced to the two fol- lowing principles : The firft principle.—Every body which paffes from the folid to the liquid ftate, abforbs a portion of heat, which is no longer fenfible to the thermometer, but exifts in a true ftate of combi- nation. The academicians of Florence filled a veffel with pounded ice, and plunged a thermometer in it, which defcended to o. The veffel was IhenimmerSed in boiling water, and the thermome- ter did not riSe during the whole time of the liquefaction of the ice. The fufion of ice therefore abforbs heat. Mr. Wilcke poured a pound of water, heated to the 6oth de- gree of Reaumur, upon a pound of ice. The melted mixture pofleffed the temperature of o. Sixty degrees of heat had there- fore entered into combination. The Chevalier Laudriani has fhewn that the fufion of metal^ of fulphur, of phofphorus, of alum, of nitre, &c. abforb heat. Cold is produced in the diflblution of all the cryftallized falts, Reaumur made a feries of very interefting experiments on this fubject, which confirm thofe of Boyle. Fahrenheit caufe4 the thermorr eter to defcend to forty degrees, by melting ice by General Properties of Heat. 79 ftrong nitrous acid. But the moft aftonifhing experiments are thofe made by Meffrs. Thomas Beddoes,*phyfician, and Walker, apothecary at OxSord, and inSerted in the Philofophieal Tranf- actions for the year 1787^ The mixtures which produced the greateft degrees of cold are, 1. Eleven parts of muriate of am- moniack, or common fal ammoniack; ten parts of nitrate of pot-afh, or common nitre ; fixteen parts of Sulphate of foda, or Glauber's fait ; with thirty-two parts by weight of water : the two firft falts fhould be dry, and in powder. 2. The nitrick acid, muriate of ammoniack, and fulphate of foda, lowered the thermometer to eight degrees under o. Mr. Walker has frozen mercury without ufing either ice or fnow. It is therefore an incontrovertible principle, that all bodies which pafs from the Solid to the liquid ftate, abforb heat, and retain it in So accurate a combination as to afford no Sign of its prefence. The heat is therefore fixed, neutralized or latent. The fecond principle.—All bodies, by paffing from the folid or fluid ftate to the aeriform ftate, abforb heat, which becomes latent; and it is by virtue of this heat that fuch bodies are plac- ed and maintained in that ftate. On this principle is founded the procefs ufed in China, India, Perfia, and Egypt, to cool liquors ufed for drink. The water intended for this purpofe is put into very porous veffels, and expofed to the fun, or to a current of warm air, to cool the fluid contained within them. It is by Similar means that cool drink is obtained in the long journies of the caravans. Interefting details on this fubject may be feen in the Travels of Chardin, vol. iii. 1723 ; Taver- nier's Voyages, vol. i. edit. 1738 ; Paul Lucas's Voyages, vol. ii. edit. 1724 ; and alfo in the Mundus Subterraneous of P. Kir- eher, lib. vi. fee. 2. cap. 2. We may conclude from the experiments of Mr. Richmann, made in 1747, and inferted in the firft volume of the imperial Academy of Peterfburgh, 1. That a thermometer taken out of water, and expofed to the air, always defcends, even when its temperature is equal or fuperiour to that of the water. 2. That it afterwards rifes, until that it has acquired the temperature of the atmofphere. 3. That the time of defcending is lefs than that which it employs to rife again. 4. That when the thermometer, * It docs not appear that Dr. Beddoes either had or pretends to have any other fliarc in the experiments of Mr. Walker than that of having tranfmittcd them to the Royal Society. | Alfo in the fubfequent volumes, 80 General Proper ties of Heat. withdrawn from the water, has arifen to the common tempera- ture, its bulb is dry ; but that it continues wet during the whole time of its Handing beneath this common temperature. To thefe confequences we fhall add others deduced from fev- eral curious experiments by the celebrated Cullen. i. A ther- mometer fuSpended in the receiver of the air pump, defcends two or three degrees during the time of exhauftion, and after- wards rifes to the temperature of the vacuum. 2. A thermom- eter plunged in alcohol, in the receiver of the air pump, always defcends, and the lower in proportion as the bubbles are ftrong- er which iffue from the alcohol ; if it be Withdrawn from this liquor, and fufpended wet beneath the receiver, it falls eight or ten degrees while the air is pumping out. It is well known that iS the ball of a thermometer be wrap- ped in fine linen, and kept moift by Sprinkling with ether, and the evaporation be facilitated by agitation in the air, the the- mometer will deScend to o. The immortal Franklin has proved, in his own perSon, that when the body perSpires Strongly, it is leSs heated than Surround- ing bodies, and that perSpiration always produces a certain de- gree of coldneSs.—See his letter to Dr. Lind. The great number of labourers in the burning heat of our climate fupport themSelves only by virtue of a copious perfpira- tion, the fluid for which they replenish by drinking plentifully. The workmen employed in glaSs-houses, founderies, &c. often live in a medium hotter than their bodies, the natural tempera- ture of which is equalized and moderated by perfpiration. If evaporation be increafed by agitation of the air, the refrig- eration is the greater. Hence the ufe of fans, ventilators, &c. which, though intended to give motion to warm air, afford like- wife the virtue of cooling by facilitating and favouring evapora* tion. Warm and dry air is beft fuited to form a refreshing current, becauSe it is more calculated to diffolve and abforb humidity; moid air is leSs proper, becauSe it is already Saturated.—Hence the neceflity of frequently renewing the air to preferve the cool* nefs of our apartments. Thefe principles have a nearer relation to medicine than is generally fuppofed. We find that almoft all fevers end in per- Spirations, which, befide the advantage of expelling the rhorbifick matter, poffefs likewife that of carrying off the matter of heat, and reftoring the body to its common temperature. The phyfi- cian who is defirous of moderating the excefs of heat in the body of a patient, ought to maintain the air in that difpofition which is moft Suitable to his views. General Properties of Heat. Si The uSe of volatile alkali is univerSally acknowledged to be of advantage in burns, the tooth-ache, &c. May not thefe effects be attributed to the volatility of this fubftance, which quickly combining with heat, carries it off, and leaves an impreffion of cold ?—Ether is a Sovereign remedy for the colick. Does not its virtue depend on the fame principles f The heat which has entered into combination with bodies during their tranfition from the folid to the liquid ftate, or from this laft to the aeriform ftate, may be again exhibited by cauf- mg thefe fubftances to return again to the States of liquefaction or folidity. In a word, every fubftartcS which paffes from the liquid to the folid State, Suffers* its latent heat to efcape, which at this inftartt beeofties free or thermametrical heat. The celebrated Fahrenheit, in the year 17 24, having left wa- ter expofed to, a colder temperature than that of ice, the Water remained fluid : but it congealed by agitation ; and the ther- mometer, which marked feveral degrees berteath the freezing point, fuddehly rofe to tnat temperature. Mr. Treiwald men- tions a fimftar fact ifi the Transactions j and Mr. de Ratte made the Same observations at fifrontpellicr. Mr. Baume has Shown,1 in his enquiries and experiments rela- ting to feveral Singular phenomena exhibited by water at the in- ftant of its congelation, that feveral degrees of heat are always developed at that inftant. Gafeous fubftances are maintained in the aeriform ftate mere- ly by the heat which is combined With them ; and when to theSe fubftances, thus diffolved in calorick, another body is preSented, to Which they have a very Strong affinity, they aban- don their heat to unite with this laft fubftance j and the calo- rick, thus expelled or difengaged, appears under the form of free or therm'o'metrical heat. This disengagement of heat, by the concretion or fixation of gafeous fubftances, was obferved by the celebrated Scheele, as may be feen in the valuable ex- periments which form the bafis of his Treatife on Air and Fire. Since the time of this great man, rigorous calculations have been made of the quantity of latent heat exifting in each of thefe gaSes : we are indebted to Meflrs. Black, Crawford, Wilcke, Dela Place, Lavoifier, &c.*for many excellent research- es on this fubject. r, 82 Properties and Effiecls of L'^g!:'. ARTICLE II. Concerning Light. It appears that Light is tranfmitted to our eyes by a pecul- iar fluid which occupies the interval between us and vifible bodies. Does this fluid arrive directly from the fun by fucceffive e- miffions or eradiations ? or is it a peculiar fluid distributed through Space, and put in action by the Sun's rotary motion^ or by any other caufe ? I fhall not enter into any difcuffion up- on this fubject, but fhall confine myfelf to point out the phe- nomena. A. The motion of light is fo rapid, that it paffes through nearly eighty thoufand leagues in a fecond. B. The elasticity of the rays of light is fuch, that the angle of reflection is equal to the angle of incidence. C. The fluid of light is ponderous : for if a ray of light be received through a hole in a window-fliutter, and the blade of a knife be prefented to it, the ray is diverted from a right line, and is inflected towards the body. This circumftance fhows that it obeys the law of attraction and fufficiently authorizes us to clafs it among other bodies of this nature. D. The great Newton Succeeded in decomposing the Solar light into [even primitive rays, which, prefent themSelves in the following crder : red, orange, yellow, green, bine, indi- go, violet. Dies prefent us with only three colours, which are red, blue, and yellow : the combinations and proportions of thefe three principles form all the Shades of colour with which the arts are enriched. Philofophers have maintained that a- mong the folar rays thefe are three primitive colours.—See Les Recherches de M. Marat. All natural bodies may be confidered as prifms which dtcom- pofe or rather divide the light. Some reflect the rays without producing any change and thefe are white ; others abforb them all, and caufe abfolute blacknefs : the greater or lefs affinity of the feveral rays with various bodies, and perhaps likewife the difpofitionof the pores, is no doubt the caufe that, when a pen- cil falls upon a body, fome rays enter into combination, while others are reflected ; and it is this which affords the diverfity of colours, and the prodigious variety of Shades under which bodies appear to our eyes. We can no longer confine ourfelves to confider light as as merely phyfical fubftance ; the chemift perceives its influence Properties and EffeBs of Light. 83 in moft of his operations, and finds it neceffary to attend to its Action, which modifies his refults : and its effects are no lefs ev- ident in the various phenomena of nature, than in the experi- ments performed in our laboratories. We fee that vegetation cannot take place without light. Plants deprived of this fluid become pale ; and when in hot- houfes the light comes to them from one part only, the vegeta- bles incline towards the aperture, as if to Show the neceflity of this beneficial fluid. Without the influence of light, vegetables would exhibit but one lifelefs colour ; they are deprived of their beautiful fhades by the interception of this luminous fluid. On thefe principles celery, endive, and other plants, are bleached. Vegetables are not only indebted to the light for their colour, but likewife for their Smell, tafle, combuftibility, maturity, and the refinous principle, which equally depend upon this fluid. Hence it is, no doubt, that aromatick Subftances, refins, and vol- atile oils, are the inheritance of Southern climates, where the light is more pure, conflant and intenfe. We See, hkewiSe, that the influence of light is evident in oth- er beings : for, as Mr. Dorthes has obferved, worms and grubs, which live in the earth or in wood, are of a whitifh colour. The birds and flying inSects of the night, are likewife diftinguifh- able from thofe of the day by the want of brilliancy of colour -f $nd the difference is equally marked between thofe oS the north and of the fouth. A very aftonifhingproperty oS light upon the vegetable kingdom is, that when vegetables are expofed to open day-light, or to the Sun's rays, they emit vital air. We Shall again attend to all theSe phenomena when we come to treat of the analyfis of vegetables. The fine experiments of Scheele and Berthollet have fhewn that the abfence or prefence of light has an aftonifhing effect upon the refult of chemical experiments. Light difengages vital air from feveral fluids, fuch as the nitrick acid, the oxigen- ated marine acid, &c. It reduces the oxides or calces of gold. Silver, &c. It changes the nature of oxigenated muriates, ac- cording to the observations of Mr. Berthollet. Light likewife determines the phenomena of vegetation exhibited by faline So- lutions, as I have fhewn. From all which circumftances it is evident that we ought to attend to the effect of this agent in almoft all our operations. " Organization, fenfation, fpontaneous motion, and life, exift only at the Surface of the earth, and in places expofed to light : we might affirm that the flame of Prometheus's torch was the espreffion of a philofophical truth which did not efcape the an- 84 Origin of Sulphur* cients. Without light, nature was lifelefs, inanimate, and dead : a benevolent God, by producing light, has Spread organization^ fenfation and thought over the furface of the earth."—Element- ry Treatife of Chemiftry by Mr. Lavoifier. We ought not to corifohnd the Solar light with the. light of our furnaces j the light of1 thefe has, as I am convinced, very evident effects in certain phenomena ; but thefe effects are flow? and fcarcely comparable with thofe of the folar light. Although heat often accompanies light, the phenomena we have mentioned cannot be attributed to mere heat. Heat may jndeed modify them where it exifts, but moft affuredly it canno| produce them. pHAFTEE II. Concerning Sulphur, WE are obliged to place Sulphur among the elements, though. Our predeceffors pretended to have determined its conftituent principles. This proceeding would appear to be retrograde, if it were not evident that the correction of miftakes is a real ad- vancement in fcience. The ancients ufed the word fiftphur to denote every com- buftible and imflammable fubftance. Accordingly we find, in all their writings, the expreffions fulphur of metals, fulphur of animals, fulphur of vegetables, Sec. Stahl affigneth a determinate value to the denomination of Sulpfiur; and Since the time of this celebrated chemift we have confined the name to denote a body of an orange-yellow colour, dry, brittle, capable of burning with a blue flame, and exhaling a penetrating odour during combuftion : when rubbed, it be- comes, electfick j and by a light preffure in the hand it cracks, and becomes reduced to powder. It appears that fulphur is formed by the decompofition oS ve- getables and animals. It has been Sound on the walls of necef- fary-houfes ; and when the ditch of the Porte St. Antoine, at Paris, was cleared, a confiderable quantity was mixed with the decayed remains of vegetable and animal fubftances, that had fih% ed the ancient ditches, and there putrefied. Mr. Deyeux has lik'ewjfe proved, that Sulphur exifts naturally in certain plants, fuch as patientia, cochlearia, &c. His pro- ceffes for extracting it confift in—i. The wafhed root muft be. reduced by raSping into 3 fine pulp; this muft be wafhed ir\ Cold water, and paffed through a Sieve or cjfoth of an open tex- procejes for f^iracllng Sulphur. ** tare : the fluid pafles in a turbid State, ?nd depofites a precipi-?^ tate, which when dried proves the exiftence of fulphur. 2- Xhe pulp may be boiled, and the fcum afforded by the ebullition afterwards dried ; the fcum contains fulphur. Several "fpecies of rumex, confounded under the name of Patience, do not con- tain fulphur. I have obtained it from the rumex patientia L, which grows on the mountains Qevennes, and is the fame which is ufed at Paris. M. Le Veillard obtained fulphur by fuffering vegetable fubftances to putrefy in well-water. Sulphur is a- bundantly contained in coal mines ; it is found in combination with certain metals ; it appears almoft always where vegetable decompofition takes place j it forms the greater part of thofe pyritous and bituminous fehifti which occupy the focus of vol- Canos; it is fublimed in thofe places where the pyrites are de- compdfed ; it is thrown out by lubterraneous fires ; and is found in greater or lefs quantities in volcanick diftrifts. Much has been Said concerning Showers of fulphur 5 but it is at prefent well known that this errour has chiefly ariSen from the powder of the Stamina of the pine, which is carried to great diftances. Henckel faw the furface of a marfh entirely covered with this powder* The known procefles for extracting fulphur in the large way, and applying it to the purpoSes of commerce, confift in difen- gaging it from the pyrites or fu.lphures of copper, or of iron, by methods poffeffing various degrees of Simplicity and economy. On this Subject, the Pyritology oS Henckel, Macquer's Chemical Dictionary, and the Metallurgical Tracts of Mr. Jars, may be confulted. In Saxony and Bohemia the ores of Sulphur are diftilled in earthen tubes diSpoSed in a gallery. The fulphur which is dif- engaged by the heat paffes into receivers placed without, and in which care is taken to keep a fufficient quantity of water. At Rammelfburg, at St. Bel, &c. large heaps of pyrites are made, which are decompofed by a gentle heat, at firit applied to the maSs from a ftratum of combiiftible matter upon which it is placed. The heat is afterwards kept up by the action of the pyrites amongft each other. The fulphur which exhales cannot efcape laterally, becauSe care is taken to cover the fides with eartb. It therefore riSes to the Summit oS the truncated pyra- mid, where if is collected in Small cavities made for that pur- poSe. The heat oS this part is Sufficient to keep the Sulphur in a fluid ftate; and it is taken out from time to time with ladles. Almoft all the fulphur uSed in France comes Srom the SolSa- tara. This volcanick country every where exhibits marks of ^he agency of Subterraneous fire. The enormous maffes of py- 85 Analyfis of Sulphur. rites which are decompofcd in the bowels of the earth produce hear, which fublimes part of the fulphur through apertures which the fire, and the effort of the vapours, have opened in all parts. The earths and ftones which contain fulphur are diflilled ; and it is the refult of this diftillation which is called Crude Sul- phur. The crude fulphur is tranfported into France by the way of Marfeilles, where it receives the neceffary preparations to render it fuitable to various purpofes. i. It is reduced into fticks or rolls, by fufing it, and pouring it into moulds : or, 2. It ig formed into flowers of brimftone by fubliming it with a gentle heat, and collecting this fulphureous vapour in a very clofe chamber of confiderable extent. This very pure and finely di- vided fulphur is diftinguifhed by the name of Flowers of Brim-; ftone, or Sublimed Sulphur. Sulphur enters into fufion by a moderate heat ; and if the moment be Seized in which the furface congeals, and the liquid Sulphur contained beneath that furface be then poured out, the internal cavity will exhibit long needle-formed cryftals of an oc- tahedral figure. This procefs, contrived by the famous Rouelle, has been applied to the cryftallization of almoft all the metals. Sulphur is found naturally cryftallized in Italy, at Conilla near Cadiz, &c Its ufual form is octahedral : but I have, neverthe- less, feen cryftals of fulphur in perfect rhomboids. Stahl thought that he had proved, by analyfis and fynthefis, that Sulphur is formed by the combination of his phlogifton with the fulphurick acid. The happy feries of proofs which he has left behind him for the eltablifhment of his opinion, has ap- peared fo complete, that, fince the time of this great man, his, doctrine has conftantly been admitted as founded on abfolute proof. This example was even urged as an inftance to fhew how high a degree of evidence the chemical analyfis was capable of affording. But our difcoveries refpecting gafeous fubftances have fhewn us, that the ancients were neceifarily led into er- rour for want of that knowledge. The immenSe refearches of the moderns into the compofition of acids, have fhewn that thefe fubftances are decompofed in a variety of operations ; and this revolution in the ftate of our knowledge muit have produced a Similar change in our methods of explaining the phenomena. An examination of the principal experiments of Stahl, upon which his doctrine effentially depends, will fufficiently fhew the truth of what we have afferted. If one third part of charcoal, and two thirds of fulphate of pot-afh, or vitriolated tartar, be mixed and fufed in a cruci- ble, the product is (liver of fulphur) lulphure of pot-afh. If this Carbcne. fulphurebe diffolved in water,and the alkali be engaged by adding a few drops of fulphurick acid, a precipitate is "afforded, which Confifts of true fulphur : « whence," fays Stahl, « the fulphur is a combination of phlogifton, or the inflammable principle of the charcoal with the fulphurick acid." The experiment was true, but the confequence is abfurd ; becaufe it would follow that ihe ful- phurick acid which was added, muft have poffeffed the property of difplacing fulphurick acid united to the alkali.* If Stahl had more ftrictly analyfed1 the refult or product of this operation, he would have been convinced that it does not contain a particle of fulphurick acid. If he had been poffeffed of the power of operating in clofed veffels, and of collecting the gafeous fubftances which are difen- gaged, he would have obtained a large quantity of carbonick acid, which arifes from the combination of the oxigene of the fulphurick acid with the charcoal. If he had expofed his liver of fulphur to the air in clofed vef- fels, he would have feen that the vital air is abforbed, that the fulphure is decompofed, and that the fulphate of pot-afh, orvit- riolated tartar is formed ; which proves the recompofition of the fulphurick acid. If charcoal be moiftened with fulphurick acid or oil of vitriol, and then expofed to diftillatio», the products are carbonick acid or fixed air, fulphur, and much fulphureous or volatile vitriolick acid. The experiments of Stahl exhibit the moft perfect demonstra- tion of the decompofition of the fulphurick acid into fulphur and oxigene ; and it is not neceffary, in the explanation of therr, either to Suppofe the exiftence of an imaginary being, or to fup- pofe that fulphur is a compounded body. CHAPTER III. Concerning Carbone. PURE charcoal is called Carbone in the new Nomenclature. This fubftance is placed among fimple bodies, becaufe no experi- ment has hitherto fhewn the poffibility of decompofing it. * Without pretending, on the prefent occafion, to dTpute either for or againft phlogirton, I fhall ohferve that this argument i* among, the nmny piralogil'ms urged on hoth fides in this controversy. If tiieie l'e any r pure fulphur.. T. &S Converfton of Bodies. Carbone exifts ready Sormed in vegetables. It may be clear- ed of all the volatile and o'ily principles by diftillation ; and, by fubfequent wafhing in pure water, it may be deprived of all the falts which ate mixed and confounded with it. When it is required td procure carbone in a State of great purity it muft be dried by Strong ignition in a clofed veffel : this precautioai is neceffary: for the laft portions of water adhere with fudi avidity, that they are deconipofed, and afford hydrogenous gas and Carbonick acid. Carbone exifts likewise in the animal kingdom : it may be extrafted by a proceSs Similar to that which we have deScribed ; but its quantity is fmall. It appears in the form of a light fpungy mafs, difficultly confumed in the air, and mixed with a great quantity of phoSphates, and even of foda. Carbone is likewife foiirid in plumbago, of which it is one of the principles. We fhall treat more fully of this fubftance in the analyfis of vegetables. But thefe concife ideas are Sufficient to enable us io proceed in our account of its combinations, which is indeed the only object of the prefent Short enumeration of its properties.' SECTION V; Concerning Gafes, or the Solution of certain Principles in Calorick, at the Temperature of the Atmofphere. (^♦ALORICK, in its combination with bodies, volatili- zes fome of them, and reduces them to the aeriform ftate. The permanence in this ftate in the temperature of the atmofphere conftitutes the gafes ; fo that, to reduce a fubftance to the ftate of gas, confifts in diffolving it in calorick. Calorick combines with various bodies, with greater or left facility; and we are acquainted with Several that, at the temper. ature of the atmofphere, are conftantly in the State oS gas: there are others which pafs to this ftate at fome degrees higher, and theSe are called Volatile or Evaporable Subftances. They differ from fixed fubftances, becaufe thefe laft are not volatilized but by the application and combination of a flrong dofe of calor- ick. It appears that all bodies do not indiscriminately require the fame quantity of calorick to affume the gafeous ftate ; and we by Heat into Gafes. So Shall fee that this proportion may be deduced from the fixation and concretion oS thefe gafeous Subftancesr To reduce any Subftance to the State of gas, the application o£ calorick may be made in various manners. The more fimple method confifts in placing the body in con- tact with another body which is heated. In this fituation, the heat on one hand diminishes the affinity of aggregation or com- position, by feparating the conftituent principles to a greater dif- tance from each other; on the other hand, the heat unites to the principles with which it has the ftrongeft affinity, and volatilizes them. This procefs is according to the method of fimple affin- ities ; for it in fact confifts of the exhibition of a third body, which, prefented to a compound of feveral principles, combines With one of them, and Carries it off. The method of double affinity may likewife be ufed to con- vert any fubftance into the gafeous form ; and this is what hap- pens when we caufe one body to act upon another to produce a combination, in which a difengagement of forae gafeous prin- ciples takes place. If I pour, for example, the fulphurick acid upon the oxiode of manganefe, the acid combines with the met- al, while its calorick feizes the oxigene, and rifes with it. This principle takes place not only in this inftance,. but on all other occaGons wherein an operation being, performed without the application of heat, there is a production of vapour or gas. The various ftates under which bodies prefent themfelves to our eyes, depend almoft entirely upon the different degrees of combination of calorick with thofe fame bodies. Fluids do not differ from folids, but becaufe they conftantly poffefs, at the temperature of the atmofphere, the dofe of calorick which is requifite to maintain them in that ftate ; they congeal and pafs to the concrete ftate with greater or lefs facility, accordingly as the requifite quantity of calorick is more or lefs confiderable. All folid bodies are capable of parting to the gafeous ftate s and the only difference which exifts between them in this refpecti is, that a dofe of calorick is • required for this purpofe, which is governed—i. By the affinity of aggregation, which connects their principles, retains them, and oppofes itfelf to a new combi- nation. 2. By the weight of the conftituent parts, which ren- ders their volatilization more or lefs difficult. 3. By the agree- ment and attraction between the calorick and the folid body, which is more or lefs Strong. All bodies, whether Solid or liquid, when they come to be volatilized by heat, appear in two ftates—that of vapour, or that of gas. M $0 Experiments on Gafes. In the firft caSc, theSe Subftances loSe, in a Short time, the ca- lorick which railed them, and again appear in their original form the moment the calorick finds colder bodies to combine with; biit it is rare that the bodies thus divided reSurhe their original confiftence. This firft ftate is that of vapour. In the fecond caSe, the Combination of calorick with the vol- atilized fubftande is Such, that the ordinary temperature of the atmofphere is insufficient to overcofne this union. This Statd constitutes the gaSes. When the combination of calorick with any fubftance h fuch that a gas is produced, thefe invifible fubftances may be managed at pleafure, by the affiftance of apparatus appropriated withiri our time to thefe ufes. Thefe apparatus are known by the name of Pneumato^chemick, Hydro-pneumatick appara- tus, &c. The prieumato-chemical apparatus, in general, confifts of a wooden veffel, ufually of a fquare form, and lined with lead or tin : two or three inches beneath the upper edge there is formed a groove, in which a wooden plank Aides, having a hole in the middle, and a notch in one of its fides; the hole is made in the centre of an excavation made in the flielf, of the figure of a funnel. This veffel is filled with water or mercury, according to the nature of the gafes operated upon. There are fome which eafi- ly combine with water, and therefore require to be received over mercury. The gafes may be extracted in various manners. When they are difengaged by fire, a recurved tube is adapted to the neck of the retort, one extremity of which is plunged in the water or the mercury of the pneumato-chemical veffel, and opens beneath the aperture in the fhelf, which is in the form of a funnel. The junction of the tube with the neck of the retort is fecured with the ufual lute *, a veffel filled with the liquid of the ciftern is inverted upon the fhelf over the aperture. When the gas is difengaged from the materials in the retort, it appears in the form of bubbles, which rife, and gain the fuperiour part of the inverted veffel. When all the water is difplaced, and the bottle is full of gas, it is withdrawn, by adapting a glafs plate fo its orifice to prevent its diffipation : it may then be poured from one veffel to another, and fubjected to a variety of experi- ments to afcertain its nature. When the gafes are difengaged by means of acids, the mix- ture which is defigned to afford them is put into a bottle with a recurved tube fitted to its neck ; and this tube is plunged in the ciftern in fuch a manner, that the bubbles of gas may pafs, Hydrogenous Gas. 91 as in the former experiment, through the aperture of the funnel in the ShelS. The proceffes a* preSent uSed to extract the gaSes, and to an- alyfe them, are fimple and commodious : and thefe proceffes have Singularly contributed to our acquifition of the knowledge of thefe aeriform fubftances, whofe difcovery has produced a revo- lution in chemiftry. CHAPTER I. Concerning Hydrogenous Gas, or Inflammable Air. INFLAMMABLE Air is one of the conftituent parts of wa- ter ; a circumftance which has entitled it to the denomination of Hydrogenous Gas. Its property of burning with vital air, has caufed it to be diftinguifhed by the name of Inflammable Air. Hydrogenous gas has been procured long fince. The famous philofophical candle attefts the antiquity of this difcovery ; and the celebrated Hales obtained from moft vegetables an air which took fire. Hydrogenous gas may be extracted from all bodies in which it is a conftituent part ; but the pureft is that afforded by de- compofition of water, and it is this fluid which ufually affords it in our laboratories. For this purpofe the fulphurick acid is poured upon iron, or zinc ; the water, which ferves as a vehi- cle for the acid, is decompofed on the metal, its oxigene com- bines with it, while the hydrogenous gas efcapes. This expla- nation, however contrary to the ancient notion, is not the lefs a dcmonftrated truth ; in fact, the metal exifts in the ftate of an oxide in its folution by the fulphurick acid, as may be proved by precipitating it with pure vegetable alkali : on the other hand, the acid itSelf is not at all decompoSed ; fo that the oxi- genous gas cannot have been afforded to the iron but by tha water. Water may be decompofed likewife ftill more directly by throwing it upon iron ftrongly heated ; and hydrogenous gas may be obtained by caufing water to pafs through a tube of iron ignited to whitenefs. The hydrogenous gas may be extracted by the fimple diftil- lation of vegetables. Vegetable fermentation, and animal pu- trefaction, likewife produce this gafeous fubftance. The properties of this gas, are as follow : A. Hydrogenous gas has a difagreeable, ftinking odour. Mr. Kirv.Mii has obferved, that when k is extracted over mercury, ife f * Hydrogenous Gast has fcarcely any Smell. It contains halS its weight of water, and loSes its fmell the moment it is deprived of this additional fub- ftance, Kirwan has likewife obferved, that the volume oS hydroge- nous gas is one eighth larger when received over water than when received over mercury. Thefe obfervations appear to prove, that the offensive fmell of this gasariSes only from the water it holds in folution. B. Hydrogenous gas is not proper for refpiration. The ab- be Fontana affures us that he could not take more than three inspirations of this air : the count Morrozo has proved that an- imals perifh in it in a quarter of a minute. On the other hand feveral northern chemifts have affirmed, in conSequence of ex- periments made on themfelves, that hydrogenous gas might be refpired without danger j and it is Some years fince the unfor- tunate Pilatre du Rozier filled his lungs with it at Paris, and fet it on fire during the expiration, which forms a very curious jet of flame. It was remarked to him that the abbe Fontana had objected againft the accuracy of the SwediSh chemifts: This intrepid philofopher anSwered the objection, by mixing one ninth of atmoSpherical air with very pure hydrogenous gas. He reSpired this mixture, as uSual ; but when he attempted to. fet it on fire, the conSequence was an explofi.on So dreadful, that he imagined all his teeth were blown out. This opposition of opinions, and contradiction of experi- ments, respecting a phenomenon which feems capable of unan- fwerable decifion by one fingle experiment, induced me to have recourfe to trial, to fix my own ideas on the fubject. Birds Successively placed in a veffel of hydrogenous gas, died, without producing theSmalleft perceptible change in the gas itSelf. i Frocs placed in forty inches of hydrogenous gas died in the fpa-jj of three hours and a half: while others lived fifty-five hours in oxigenous gas and atmoSpherick air ; and when 1 took, thei-i out ftill living, the air was neither vitiated nor diminished. Numerous experiments which I have made upon theSe animals have led me to obServe that they have the faculty of flopping their refpiration, when placed in any noxious gas, to fuch a de- gree, that they inSpire only once or twice, and aSterwards fuk pend every function on the part of the refpiratory organ. I have Since had occafion to obServe that theSe animals are not reduced into a putrid mafs by remaining in hydrogenous gas, as was affirmed fome time ago. The fact which may have im- poSed on chemifts who related this circumftance, is, that frogs are often enveloped in a mucus or Sanies, which appears to cov- er them ; but they exhibit the fame phenomenon in ail the gaSes. or Inflammable Air. n After having tried the hydrogenous gas upon animals, I de- termined to refpire it myfelf ; and J found that the fame vol- ume of this air might be feveral times refpired without danger. But I obferved that this fgas was not changed by thefe opera- tions ; whence I concluded that it is not refpirable : for, if it were, it would fuffer a change in the lungs, the object of refpi- ration not being confined to the reception and emiffion of a fluid merely ; it is a function much more noble, more intereft- ing, more intimately connected with the animal economy : and we ought to confider the lungs as an organ which is nourifhed by the air, digefts that which is prefented to it, retains the ben- eficial, and rejects the noxious part. Since, therefore, inflam-* mable air can be refpired feveral SucceSfive times without dan- ger to the individual, and without any alteration or change in it- felf, we may conclude indeed that inflammable air is not a poi- fon, but that it cannot be confidered as an air effentially proper to reSpiration. It is with hydrogenous gas in the lungs, as with thofe balls of mofs and refin which certain animals Swallow during the rigorous Seafon oS the winter. TheSe balls are not digefted, fince the animals void them at the return of fpring ; but they delude hunger, and the membranes of the ftomach are exereifed upon them without danger, in the fame manner as the lungs exert themfelves upon the hydrogenous gas prefented to them. C. Hydrogenous gas is not combuftible alone ; it does not burn but by the concurrence of oxigene. If a veffel filled with this gas be reverfed, and a lighted taper he prefented to it, the hydrogenous gas is Sound to burn at the Surface of the veffel; but the candle is extinguifhed the moment it is plunged lower. The moft inflammable bodies, fuch as phofphprus, do not burn in ari atmofphere of hydrogenous gas. D. Hydrogenous gas is lighter trnn common air. One cu- bick foot of atmofpherick air weighs Seven hundred and twenty grains ; a cubick foot of hydrogenous gas weighs feventy-two grains. The barometer being at 20/ 9, and the thermometer 0o° Fahrenheit, Mr. Kirwan found the weight of this air to that of common air as eighty-four to one thoufand ; consequently it was about twelve times as light. Its Specifick gravity varies very much, becauSe it is difficult to obtain it conftantly of the fame degree of purity. That which is extracted from vegetables contains the carbonick acid and oil, which increafes its weight. This levity of hydrogenous gas has caufed certain philofophers to prefume that it ought to arrive at and occupy the fuperiour part of our atmofphere ; and upon this fuppofttion the moil brill- 94 Hepatkk Gas. lant conjectures have been made respecting the influence which a itratum oS this gas, predominating over the reft of the atmof- phere, ought to produce in meteorology. They were not aware that this continual lofs of matter is not agreeable to the wife e- conomy of nature. They did not obferve that this gas, during its afcent in the air, combines with other bodies, more efpecially oxigene, and that water and other products are the refult ; the: knowledge of which muft neceffarily lead us to that of moft meteors. The theory of balloons, or ae'roftatick machines, is founded on this levity of the hydrogenous gas. In order that a balloon may rife in the atmofphere, it is fuffi- cient that the weight of the balloon itfelS, and the air it inclo- fes, Should be lefs confiderable than that of an equal bulk of at- moSpherick air ; and ft muft riSe till its weight is in equilibrio with an equal volume of the furrounding air. The theory of the Montgolfiers is very different from this. In this cafe a given volume of atmofpherick air is rarefied by heat, and kept feparated from the common mafs by a hollow veffel of cloth. This rarefied fpace may therefore be confider- ed Sor a moment as confifling of a maSsof air oS greater levity, which muft neceffarily make an effort to rife in the atmofphere," and carry its covering along with it. E. Hydrogenous gas exhibits various characters, according to its degree of purity, and the nature of the fubftances which are mixed with it. It feldom happens that this gas is pure. That which is afford-^ ed by vegetables contains oil, and the carbonick acid. The in- flammable air of marfhes is mixed with a greater or lefs quanti- ty of carbonick acid ; and that which is afforded by the decom- pofition of pyrites fometimes holds fulphur in folution. The colour of hydrogene, when fet on fire, varies according to its mixtures. One third of the air of the lungs, mixed with the inflammable air of pit-coal, affords a flame of a blue colour ; inflammable air, mixed with nitrous air, affords a green colour \ the vapour of either affords a white flame. The various mix- tures of thefe gafes, and the degree of compreffion to which they are fubjected, when exprefledout of an aperture in order to burn them, have, in the hands of certain operators, afforded very agreeable illuminations, well deferring the attention of learned and curious obfervers. F. Hydrogenous gas poffeffes the property of diffolvimg Sul- phur. In this caSe it contracts a iiinking imcl", and Sorms h<,- patickgas. Hepatick Gas. 9$ Mr. Gengembre put fulphur into inverted veffels filled with hydrogenous gas, and diffolved it by means oS the burning-gUSs. The hydrogenous gas, by this treatment, obtained all the char- acteriftick properties oShepatick gas. The Sormation of this gas is almoft an effect of the decompo- fition of water. In fact, the alkaline Sulphures, or livers of Sul- phur, do not emit any diSagreeable Smell while they are dry ; but the moment they aremoiftened, an abominable Smell is perceived, and Sulphate of pot-afh, or vitriolated tartar, begins to be formed. Thefe phenomena prove that the water is decom- pofed ; that one of its principles unites to the fulphur, and vol- atilizes it; while the other combines with the alkali, and forms a more fixed product. Sulphurated hydrogenous gas may be obtained by diffolving the fulphures or hepars by acids. Thofe acids in which the ox- igene is moft adherent difengage the greateft quantity. The muriatick acid produces twice as much as the fulphurick. That which is produced by this laft, burns with a blue flame ; but that which is difengaged by the muriatick acid, burns with a yellowifh white flame. Scheele has taught us the means of obtaining this gas in great abundance, by decompofing artificial pyrites, formed bv three parts of iron and one of fulphur, to which fpirit of vitriol is added. The natural decompofition of pyrites in the bowels of the earth produces this gas ; which efcapes with certain waters, and communicates peculiar virtues to them. The moft general properties of thefe gafes are ; i. They render the white metals black. 2. They are improper for refpiration. 3. They impart a green colour to fyrup of violets. 4. They burn with a light blue flame, and depofite Sulphur by this combuftion. 5. They mix with the oxigenous gas of the atmofpherick air* and form water ; at the Same time that the Sulphur, beSore held in Solution, Sails down. Hence it happens that Sulphur is found in the channels oS hepatick waters, though their analyfis doe.* not (how the exiftence of an atom of that fubftance held in So- fa t ion. 6. They impregnate water, and are fparingly foluble in that fluid ; but heat or agitation diffipates them again. The air which burns at the furface of certain Springs, and forms what is known by the name of the burning fprings, con- fifts of hydrogenous gas holding phofphorus in folution. It Smells like putrid fifh. The Vcrc L impi has discovered one of theSe Spring in the ifles of St. Colombar. Dauphiny exhibits. p6" t'ital Air. another fimilar Spring at the distance of four leagues from Gre- noble. The ignis fatui which glide along burying-grounds* and which the Superstitious people SuppoSe to confiSt of the fpirits of the departed, are phenomena of this nature, which we fhall Speak of when we come to treat of phoSphorus. CHAPTER It Concerning Oxigenous Gas, or Vital Air. THIS gaSeous Substance was discovered by the celebrated Prieftly, On the firft of Auguft 1774. Since that memorable day, means have been devifed of obtaining it from various fub- ftances ; and its properties have Shown that it is a production of the moft interefting nature in the knowledge of chemiftry. No part of the atmofphere exhibits vital air in its greateft de- gree oS purity. It is always combined, mixed, or altered by Other Subftances. But this air, which is the moft general agent in the operations of nature, exifts in combination with various Subftances ; and it is by their decompofition that it maybe extracted and procured. A metal expoSed to the air becomes changed: and theSe chang- es are produced only by the combination of" the pure air with the metal itfelf. Simple diftillation oS Some of thefe metals thus changed, or oxides, is fufficient to difengage this vital air ; and it is then obtained in a very pure ftate, by receiving it in the hydro-pneumatick apparatus. One ounce of red precipitate aS- fords about a pint. All acids have vital air Sor their bafe j there are Some which yield it eafily. The diftillation oS nitre decompoSes the nitrick acid ; and about twelve hundred cubick inches of oxigenous gas are obtained Srom a pound oS this Salt. The nitrick acid when diftilled from various fubftances, is de- compofed, and its conftituent parts may be obtained feparately. Meffrs. Prieftly, Ingenhoufz, and Sennebier difcovered near- ly at the fame time, that vegetables expofed to the light of the fun emit vital air. We fhall elfewhere fpeak of the circum- ftances of this phenomena ; but fhall at prefent confine our- felves to the obfervation, that the emiffion of vital air is propor- tioned to the rigour of the plant, and the vivacity of the light; and that the direct emiffion of the rays of the fun is not necef- fary to produce this gafeous dew ; it is fufficient that the plant be well enlightened, in order that it may trhnfpire pure air } for I have often collected it in abundance froni a kind of rnofs Vital Air. 97 which covers the bottom oS a veffel filled with water, and So Well defended that the fun never Shone directly upon it. In order to procure the vital air which is diSengaged Srom plants, it is Sufficient to encloSe them beneath a glaSs veffel fil- led with water, and inverted over a tub filled with the fame flu- id. The moment the plant is acted on by the fun, fmall bub- bles of air are formed on its leaves, which detaching them Selves j rife to the upper part of the veffel, and diSplace the liquid. This dew of vital air is" a beneficial gift of nature, to repair ineeffantly the confumption of vital air. The plant abforbs at- moSpherical mephitis, and emits vital air. Man, on the con- trary, is kept alive by vital air, and emits much mephitis. It appears thereSore that the animal and vegetable kingdomslabour for each other ; and that by this admirable reciprocity oS Ser- vice the atmoSphere is continually repaired, and an equilibrium is maintained between its conftituent principles. The influence of Solar light is not confined to the production of vital air by its action upon vegetables alone ; it has likewife the Singular property of decomposing certain Subftances, and diSengaging this gas. A bottle oS oxigenated muriatick acid, expofed to the Sun, fuffers all the fuperabundant oxigene which it contained to ef- cape, and paffes to the ftate oS ordinary muriatick acid. The Same acid, expoSed to the Sun in a bottle wrapped in black pa- per, does not Suffer any change ; and, when heated in a dark place, is even reducible into gas without decompofition. The nitrick acid likewiSe affords oxigenous gas, when expoSed to the Sun ; whereas he2t alone volatilizes it without decompofition. The muriate, or marine Salt of Silver, placed under water, and expoSed to the Sun, Suffers oxigenous gas to eScape Srom it. I have obServed that red precipitate likewiSe affords oxigene in Similar caSes, and that it becomes black in no very long Space of time. We may likewife obtain oxigenous gas by difengaging it frorri its bafis by means oS the Sulphurick acid. The proceSs to which I give the preference, on account oSits fimplicity, is the follow- ing :—I take a Small apothecary's phial, into which I put one or two ounces oS manganeSe, and pour thereon a Sufficient quan- tity oS fulphurick acid to form a liquid palle. 1 afterwards fit a cork to the opening of the bottle, with a hole through it, into which is inferted a recurved tube ; one of whofe extremities enters the bottle, while the other is placed under the fhelf of the pneumato-chemical apparatus. When the apparatus is thus difpofed, I preSent a Small coal to the lower part of the bottle, and oxigenous gas is immediately diSengaged, N 9* Vital Air. The manganefe I ufe was discovered by me at St. Jean de* Gardonnenque. It affords its oxigene with Such facility, that' nothing more is neceffary Sor this purpoSe than to incorporate it with the Sulphurick acid. This gas is not perceptibly mixed with nitrigenous gas (or phlogifticated air) ; and the firft bub- ble is as pure as the laft. Oxigenous gas exhibits certain properties, according to its de- gree of purity. Thefe depend in general upon the fubftances which afford it. That which is obtained from the mercurial oxides almoft always holds a fmall quantity of mercury in folu- tion : I have been a witnefs to its having produced a fpeedy Sal- ivation on tv/o perfons who ufed it for diforders of the lungs. In confequence of thefe obfervations, I filled bottles with this gas, expofed them to an intenfe cold, and the fides became ob- fcured with a Stratum of mercurial oxide, in a ftate of extreme' divifion. I have feveral times heated the bath, over which I caufed this gas to pafs ; and I obtained at two different times a yellow precipitate in the bottle in which Ihad received the gas. The oxigenous gas extracted from plants is not equally pure with that afforded by the metallick oxides: but from whatever fubftances it is obtained, its general properties are the following. A. It is more ponderous than the air of the atmofphere ; the cubick foot of atmofpherical air weighing feven hundred and twenty grains, while the cubick Soot of pure air weighs feven hundred and Sixty-five. According to Mr. Kirwari, its weight » is to that of common air as eleven hundred and three to one tboufand. One hundred and Sixteen inches of this air weighed 39,09- grains ; one hundred and Sixteen inches oS common air weighed' 35^38 grains at the temperature of ten degrees of Reau- mur, and twenty-eight inches of preffure. One hundred parts of common air weighed forty-fix, arid, one hundred parts of vital' air fifty. B. Oxigenous gas is the only fluid proper for combuftion. This acknowledged truth caufed the celebrated Scheele to give it the name of Air of Fire. To proceed with greater order in the examination of one of the moft important properties of oxigenous gas, fince it belongs exclusively to this fluid, we fhall lay down the four following principles, as inconteftible refults of all the known facts. The firft principle.—Combuftion never takes place without vital air. The Second principle.—In every combuftion there is an ab- sorption oS vital air. The third principle.—There is an augmentation of weight in! the product; of combuftion equal to the weight of the vital air abforbed* Vital Air. 99 The fourth principle.—In all combuftion there .is a disengage- ment oSheat and light. I. The firft of theSe propofitions is a ftrict truth. Hydrogen- ous gas does not burn alone, without the affiftance of oxigene ; and all combuftion ceafes the moment that oxigenous gas is wanting. II. The fecond principle contains a truth no lefs general. If certain bodies, fuch as phofphorus, fulphur, &c. be burned in very pure oxigenous gas, this is abforbed to the laft particle ; and when the combuftion is effected in a mixture of feveral gaSes, the oxigene alone is abforbed, and the others remain un- changed. In the flower combuftions, Such as the rancidity oS oils, and the oxidations of metals, there is equally an abforption of oxi- gene, as may be fhewn by confining thefe bodies in a determi- nate mafs of air. III. The third principle, though not lefs true than the preced- ing, requires more explanation ; and for this purpofe we fhall diftinguifti thofe combuftions whofe refult, refidue, and pro- duct are fixed, from thofe which afford volatile and fugacious fubftanees. In the firft caSe the oxigenuous gas quietly com- bines With the body ; and by weighing the Same body the moment the combuftion has .completely taken place, it is eafiiy aScertained whether the increaSe in weight be proportioned to the oxigene abSorbed. This happens in all-the cafes wherein the metals are oxided, or oils rendered rancid ; and in the pro- duction of certain acids, fuch as phofphorick, thefulphurick,&c. In the fecond cafe, it is more difficult to weigh all the refults of the combuftion, and confequently to afcertain whether the aug- mentation in weight be proportioned to the quantity of the air abforbed. Neyerthelefs, if the combuftion be made in inver- ted veffels, and the whole of the products be collected, it is found that their augmentarion in weight is ftrictly equal to that of the air abforbed. IV. The fourth principle is that whofe applications are the moft interefting to be known. In moft combuftions, the oxigenous gas becomes fixed and concrete. It therefore abandons the calorick which maintain- ed it in the aeriform ftate j and this calorick being fet at liber- ty produces heat, and endeavours to combine itfelf with the fubftances neared at hand. The diSengagement oS heat is thereSore a conflant effect in nil the caSes wherein vital air is fixed in bodies ; and it follows from this principle—i. That heat is moll eminently refident in the oxigenous gas which maintains combuftion. 2. That IOC* Vital Air. the more oxigene is abforbed in a given time, the Stronger will be the heat. 3. That the only method of producing a violent, heat confifts inhuming bodies,in the pureft air. 4. That fire and heat muft be more intenfe in proportion as the air is more condenfed. 5. That currents of air are neceffary to maintain and expedite combuftion. It is upon this principle that the theory of the effects of the cylinder lamps is founded : the cur- rent of air which is renewed through the tube, fupplies frefli air every inftant ; and by continually applying a new quantity of oxigenous gas to the flame, a heat is produced Sufficient to ignite and deftroy the Smoke. It is likewiSe on the Same principle that we explain the great difference that exifts between heat produced by a flow combuf- tion, and that which is afforded by rapid combuftion. In the latter cafe the fame quantity of heat and light is produced in a fecond, which might have been produced in the other cafe in a much longer time. The phenomena of combuftion, by means of oxigenous gas, depend likewiSe upon the Same laws. Profeffor Lichtenberger, of Gottingen, Soldered the blade of a knife to a watch fpring by means of oxigenous gas ; Meffrs. Lavoifier and Erhmann have fubjected almoft all the known bodies to the action of fire maintained by oxigenous gas alone ; and they produce effects which the burning-glafs could not have operated. Mr. IngenhouSz has fhewn us that iS an iron wire be bent into a Spiral Sorm, and any combuftible Subftance whatever be fixed to one of its ends, and fet on fife, the wire will itSelf be fuSed by plunging it into oxigenous gas. - Mr. Forfter, of Gottingeq, found that the light of glow- worms is fo beautiful and bright in oxigenous gas that one fingle infect was fufficient to afford light to read the Anonces Savantes of Gottingen, printed in a very fmall character. Nothing more is wanting therefore than to apply this air to combuftion with facility and economy ; and Mr. Muef- pier has Succeeded in this, by constructing a fimple and com- modious apparatus. On this fubject the treatife of Mr. Erh- mann on fufion may be confulted. The defcription cf the gazometcr may likewife be feen in the Elementary Treatife of Chemiitry, by Mr. Lavoifier. We fhall diftinguifh three ftates in the very act of combuf- tion—ignition, inflammation, and detonation. Ignition takes place when the combuftible body is not in the aeriform ftate, nor fufceptible of affuming that ftate by the fim- ple heat of combuftion. This happens when well-made char- coal is burned. Vital Air.. £0J When the combuftible body is prefented to oxigenous gas, Jn the form of vapour or gas, the refult is flame ; and the flame is more confiderable, in proportion as the combuftible body is more volatile. The flame of a candle is not kept up but by the volatilization of the wax, which is continually effected by the? heat of the combuftion. Detonation is a fpeedy and r|pid inflammation, which occa- fions a noife by the inftantanecus formation of a vacuum. Moft detonations are produced by the mixture of hydrogenous and oxigenous gas, as I have fhewn in my Memoir upon Deto- nations, in the year 1781. It has been fince proved, that the product of the rapid combuftion of thefe two gafes is water. Very ftrong detonations may be produced by burning a mixture of one part of oxigenous gas with two of hydrogene. The effect may be rendered ftill more terrible, by caufing the mixture to pafs through foap-water, and fetting fire to the bubbles which are heaped on the furface of the fluid. Chemiftry prefents feveral cafes in which the detonation arifes from the Sudden formation of fome gafeous fubftances, fuch as that which is produced by the inflammation of gunpow- der ; for in this cafe there is a fudden production of carbonick acid, of nitrogene gas, &c. The production or inftantaneous cre- ation of any gaS whatever muft occafion a fhock or agitation |n the atmofphere, which neceffarily affords an explofion ; the effect o£ thefe explofions increafes, and becomes ftronger, from the oppofkion of any obftacles againft the efcape of the gas. C. Oxigenous gas is the only gas proper for refpiration. It is the moil eminent property which has entitled it to the name of Vital Air ; and we Shall give the preference to this denom- ination in the prefent article. It has long fince been known that animals cannot live without the affiftance of air. But the phenomena of refpiration have been very imperfectly knpwn until lately. Of all the authors who have written concerning refpiraticn, the ancients are thofe who have had the moft accurate ideas of it. They admitted in the air a principle proper to nourifh and fupport life, which they -denoted by the name of pabulum vita e and Hippocrates exprefsly favs, fpir'.tus etiam alimentum efl. This idea, which was connected with no hypothefis, has been fucceffively replaced by Syftems void oS all Soundation. .Some- times the air has been confidered as a Stimulus in the lungs, which kept up the circulation by its continual action. Vide Haller.—Sometimes the lungs have been confidered as bellows defigned to cool the body, heated by a t-houfand imaginary icaules ; and when it was proved that the volume of air was i ©2 Vital Air. dimimfhed in the lungs, it was thought to be an explanation ol every difficulty, to fay that the air was deprived of its Spring. At this day, however, we are enabled to throw Some light on one of the moft important functions of the human body. In order to proceed with more perfpicuity, we fhall reduce our notions to Several principles. 1. No animal can live withoit the affiftance of air. This fact is univerSally admitted ; but it has not been known until lately that the faculty which the air poffeffes, of anfwering the pur- poSe of reSpiration, ariSes only from one of the principles of atrr.ofpherick air, known by the name of vital air. 2. All animals do not require the fame purity in the air. Birds, as well as men, and the greateft part of quadrupeds, re- quire a very pure air ; but thofe which live in the earth, or which hide themfelves in a ftate of ftupefaction during the winter, can fubfift by means of a lefs pure air. 3. The manner of refpiring the air is different in the feveral fubjects. In general, nature has given to 3nimals an organ, which by its involuntary dilation and contraction receives and and expels the fluid in which the animal moves and exifts, This organ is more or lefs perfect, more or lefs concealed and defended from external injury, according to its importance, and influence upon the life of the creature, as Mr. Brouffonnet has obferved. Amphibious animals reSpire by means of lungs : rJut they can fufpend their motion even whilft they are in the air ; asT have obferved with regard to frogs, which flop their refpiration at pleafure. The manner of refpiration in fifties is very different; thefe animals come from time to time to inhale the air at the furface - ated by reSpiration when it is not renewed, and Shows why the air of theatres is in general So unwholeSome. II. The firft effect which the air appears to produce upon the blood is, that of giving it a vermillion colour. If the blackifh venous blood be expoSed in a pure atmoSphere, it becomes of a vermillion-colour at its Surface: this fact is daily obferved when blood is Suffered to remain expoSed in a porringer to the air. Air which has remained in contact with blood extinguishes can- dles, and precipitates lime-water. Air injected into a de- terminate portion of a vein between two ligatures, renders the blood of a higher colour, according to the fine experiments of Dr. Hewfon. The blood which returns from the lungs is of a higher colour, according to the obfervations of Meffrs. Cigna, Hewfon, &c. Hence arifes the great intenfity of the colour of arterial blood, compared with venous blood. Mr. Thouvenel has proved, that by withdrawing the air which is in contact with the blood, it may be again made to lofe its colour. Mr. Beccaria expofed blood in a vacuum, where it remained black, but affumed the moft beautiful vermillion colour as foon as it was again expofed to the air. Mr. Cigna covered blood with oil, and it preferved its black colour. Dr. Prieftly caufed the blood of a fheep to pafs fucceflively into vital air, common air, mephitick air, &c. and he Sound that the blacfceft parts affumed a red colour in refpirable air, aad that the intenfity oS this colour was in proportion to the quantity of vital air prefent. The fame philofopher filled a bladder with blood, and expofed it to pure air. That portion of blood which touched the Surface of the bladder, became red, while the internal part remained black ; an abforption of air therefore took place through the bladder, in the fame manner as when the contact is immediate. O T06 Vital Air. All thefe facts inconteflibly prove, that the vermillion colduV affumed by the blood in the lungs, is owing to the pure air which combines with it. The vermillion colour of blood is therefore the firft effect of the contact, abforption, and combination of pure air with the blood. The fecond effect of refpiration is to eftablifh a real focus of heat in the lungs ; which is a circumftance very oppofite to the i precarious and ridiculous notion of thofe who have confidered -tf the lungs as a kind of bellows defigned to cool the human body. Two celebrated phyficians, Hales and Boerhaave, have ob- ferved that the blood acquired heat in paffing through the lungs j and modern phyfiologifts have eftimated this augmentation of heat at eleven hundredths. f The heat in each claSs of individual animals is proportioned io the magnitude of their lungs, according to Meffrs. De Bufforf and Brouffonet. Animals with cold blood have only one auricle and one ven- tricle, as Ariftotle obServcd. PerSons who have reSpired viral a*r, agree in affirming that they have perceived a gentle heat viviSying the lungs, and infen- fibly extending from the breaft into all the other parts of the body. Ancient and modern facts unite therefore to prove, that a >" focus of heat really exifts in the lungs, and that it is maintained and kept up by the air of refpiration. We are able, at prefent, to explain all thefe phenomena. In fact there is an abforption of vital air in refpiration. Refpiration- then may be confidered as an operation by means of -which vital- air paffes continually from the gafeous to the concrete ftate : it muft therefore at each inftant abandon the heat which held it in folution, and in the ftate of gas. This heat produced at every infpiration muft be proportioned to the volume of the lungs, to the activity of this organ,-to the purity of the air, tire rapidity of the inflations, &c. Hence it follows that, during the winter, the heat produc- ed muft be more confiderable, becaufe the air is more condenfed, and exhibits more vital air under the fame volume. By the fame reaSon, refpiration ought to produce more heat in the inhabit- ants oS northern climates ; and this is one of the caufes prepar- ed by nature to temperate, and continually balance, the extrerrrc cold of thefe climates. It follows likewife that the lungs of afth- inatick perSons are leSs capable oS digefting the air; and I am aS- fured that they emit the air without vitiating it: from which cauSe their complexion is cold, and their lungs continually languifh-- ipg -r vital air is thereSore wonderfully comfortable to them.- Vital Air- lol It may be eafily conceived from thefe principles why the heat ©f animals is proportioned to the volume of their lungs ; and why thofe which have oply one auricle, and one ventricle, have cold blood, &c. The phenomena of refpiration are therefore the fame as thofe of combuftion. Vital air, by combining with the blood, forms the carbonick acid, which may be confidered as antiputreScent as long as it re- mains in the circulation; and that it is afterwards emitted through the pores of the fkin, according to the experiments of the count De Milly, and the obfervations of Mr. Foquet. Vital air has been ufed with fuccefs in certain diforders of the human body. The obfervations of Mr. CaiUens are wejl known. He caufed perfons affected with phthifical diforders to refpire it with the greateft fuccefs. I have myfelf been a witnefs to the moft wonderful effects of this air in a fimilar cafe. Mr. I)e B-----.— was in the laft ftage of a confirmed phthifis. Ex- treme weaknefs, profufe fweats, a flux of the belly, and in Short every Symptom announced the approach of death. Qne of my friends, Mr. De P—-, put him on a courfe of yital ai|r. The patient refpired it with delight, and afked for if with ajl the ea, gernefs of an infant at the breaft. TJuring the time that he ref- pired it he felt a comfortable heat, which diftributed itfelf jthrough all his limbs. His ftrength increafed with the greateft rapidity; and in fix weeks he was able to take long walks. This ftate of health lafjed for fix months : but after this interval he relapfed ; and being no longer able to have recpurfe to the ufe of vital air, becaufe Mr. De P-----had departed for Paris, he died.—I am very far from being of opinion that the refpiration of vital air ought to be ponfidered as a fpecifick, in cafes of this nature, I am even in doubt whether this powerful air is per- fectly adapted to fuch circumftances; but it infpires'cheerful- neSs renders the patient happy, and in deSperate cafes it is moft certainly a precious remedy, which cap Spread flowers on the borders of the tomb, and prepare us in the gentleSt manner for the laft dreadful effort of nature. fhe abfolute neceflity of vital air in refpiration, enables us to lay down pofitiye principles for purifying the corrupted'air of any given place. This may be done in three ways. The firft confifts in correcting the vitiated air by means oS Subftances which are capable oS Seizing the noxious principles. The Second confifts in displacing the corrupted air, and Subftituting SreSli air in the room oS it; as is done by mqans oS ventilators, the agita- tion of doors, (&c And the third confifts in pouring into the mephitiSed atmoSphere a new quantity of vital air. 1 oB Nitrogene Gas. The proceffes employed in purifying corrupted air, are riot all certain in their effects The fires which are lighted for this pur- pofe have no other advantage than to eftablifh afcending cur- rents, and to burn unhealthy exhalations ; and perfumes do qothing more than difguiSe the bad Smell, without changing the nature of the air, as the experiments of Mr. Achard thtvir. CHAPTER HI. Concerning Nitrogene Gaj, Azote, or Atmofpherical Mephitis. TV has teen long fince ascertained, that air which has Served the purpofes of combuftion and refpiration, is no longer proper for thofe ufes : the air thus corrupted has been distinguished by the names of phlogifticated Air, MephitiSed Air, Atmofpherical Mephitis, Sec. I call it Nitrogene Gas, for the reaSons explained ift the preliminary diScourSe. But this refidue of combuftion or refpiration is always mired "With a Small quantity of vital air and carbonick acid, which must be removed in order to have the nitrogene gas, in a ftate of purity. There are Several methods which may be ufed to obtain nitrogene gas, in a very pure ftate. i. Scheele has taught us, that by expofing fulphure of alkali ipr liver of fulphur, in a veffel filled with atmofpherical air, the Vital air is abforbed \ and, when the abforption is complete, the hitrogene g^s remains pure. By expofing, in afmofpherick air over mercury, a mixture of iron and fulphur, kneaded together with water, Mr. Kirwan obr tained nitrogene gas lo pure, that it fuffered no diminution by nitrous gas. He deprived it of all humidity, by fucceffively in- troducing dried blotting-paper into the veflel which contained it. Care miifl be taken to withdraw this air in time from the parte Which affords it ; Otherwise it will be mixed with hydrogene or inflammable gas, which is afterwards diSengaged. 2. When by any means, Such as the oxidation of metals, the rancidity of oils, the combuftion of phofphorUs, Sec. the vital air of the at- moSphere is abSorbed, the refidue is nitrogene gas. All thefe proceffes afford methods of greater or lefs accuracy to determine the proportions of vital air and nitrogene gas in the compofition of the atmofphere. 3. This mephitis may likewife be procured by treating muS- cular flefh, or the well wafhed fibrous part of blood, with ni- trick acid in the hydro-pneumatick apparatus. But it muft be Attnofpherick Air. top earefully obferved that thefe animal matters ought to be frefh ; for, if they have begun to be changed by the putrid fermenta* tion, they afford carbonick acid mixed with hydrogene gas. A. This gas is improper for refpiration and combuftion. B. Plants live in this air, and freely vegetate in it. C. This gas mixes with the -other airs, without combining with them. D. It is lighter than the atmofphcrick air, the barometer flanding at 30.46, and Fahrenheit's thermometer at 60 : the weight of nitrogene gas is to that of common air as nine hun- dred and eighty-five to one thoufand. E. Mixed with vital air, in the proportion of 72 to 28, it conftitutcs our atmofphere. The other principles which anal- yfis exhibits in the atmofphere, are only accidental, and by no means neceffary. SECTION VI. Concerning the mixture of Nitrogene and Oxigene Gas; or of Atmof- pherick Air. 1 HE gafeous fubftances we have treated of feldom exift alone and infulated ; nature prefents them every where to our observation in a ftate of mixture or of combination. In the firft cafe thefe gafes preferve the aeriSorm ftate ; in the fecond they for the moft part form fixed and Solid bodies. Na- ture, in its Several decompositions, reduces almoft the princi- ples of bodies into gas. Thefe new fubftances unite together, combine, and from thence refult compounds of confiderable Simplicity in their principles, but which become complicated by fubfequent mixtures and combinations. We may follow the operations of nature, ftep by ftep, without departing from the plan we have adopted. The mixture of about feventy-two parts of nitrogene gas, and twenty-eight of oxigene, form this fluid mafs in which we live. Thefe two principles are fo well mixed, and each of thera is fo neceffary to the fupport of the various functions of individu- als which live or vegetate upon the globe, that they have not yet been found feparate and alone. The proportion of thefe two gafes is fubject to variation in the mixture which forms the atmofphere ; but this difference depends only upon local caufes ; and the moft ufual propor- fpn is tJiat which we have her? mentioned. 110 Aimofpherich Air. The characteriftick properties of vital air are modified by thofe of nitrogene gas, and thefe modifications even Seem tQ be neceffary : Sor if we were to refpire vital air in its ftate of purity it would quickly confume our liSe; and this virgin air is no m0re Suitable to our exiftence than diftilled water. Nature does not appear to have defigned us for the ufe of thefe prin-r copies in their greateft degree of perfection. The atmofpherick air isi elevated Several leagues above our heads, and fills the deepeft Subterraneous cavities. It is in- vifible, infipid, inodorous, ponderous, elaftick, Sec. It was the only gafeous fubftance known before the pr.eSent epocha of chemiftry ; and the infinite gradations of all the invifible fluids which prefented themSelves So frequently to the obfervation of philofophers, were always attributed to modifications of the air. Almoft the whole of what has been written upon the air relates only to its phyfical properties. We fhall confine our- felves to point out the chief of thefe. A. Air is a fluid qf extreme rarefaction, obedient to the fmalleft motion; the flighteft percuffion deranges it j and its equilibrium, which is continually deftroyed, is continually en- \ deavouring to reftore itfelf. Though very fluid, it paffes with difficulty through orifices by means of which groffer liquids can eafily penetrate. This has caufed philofophers to SuppoSe that its parts were of a branched form.* B. The atmofpherick air is invifible. It refracts the rays of lio-ht without reflecting them : for it is without Sufficient proofs that fome philofophers have imagined that large maffes of this fluid are of a blue colour. It appears that the air is inodorous itfelf ; though it is the vehicle of odorant particles. It may be confidered as infipid ; and when its contact affects us varioufly, we ought to attribute it to its phyfical qualities. C. It was not until the middle of the laft century that its weight was afcertained by accurate experiments. The impof- fibility of Supporting water in a tube ppen at the bottom, to a greater height than thirty-two Seet, caufed Torricellius to Sus- pect that an external cauSe Supported the liquid at that height, and that it was not the horrour oS a vacuum which precipitated the water in the barrels oS pumps. This celebrated philofopher filled a tube cloSed at one oS its extremities with mercury : b; * This is a deception. It i? true that the cohefive attraction renders it difficult to dilplace any denfe fluid from a Capillary tuht hy the intrufion of air ; iiut every experiment ol fhe air pump, the condenfor, and the barora- tter, ihows with what facility the air paffes through the fmalleft ©rifices. T. General Properties of Water: jri reverSed this into' a veffel filled with the Same metal; and observ- ed that the mercury, after feveral ofcillations, conftantly Subfid- cd to the height of twenty-eight inches. He immediately Saw fhat the difference of elevations corresponded with the relative weights of thefe two fluids,' which are in the proportion of four- teen to one. The immortal Pafchal proved, fome time after- wards, that liquids were Supported at this elevation by a column oS atmoSpherical air ; and he afceftained that their height va- ries according to the length of the column which preffes upon ihem. D. The elafticity of the air is one of the properties upon which natural philofophers have made the greateft number of experi- ments •, and it has even been applied to confiderable advantage in the arts. SECTION VII. Concerning the Combination of Oxigenous Gas and Hydrogene, whicft forms Water. W ATER has been long confidered as an elementary principle ; and v/hen accurate experiments had compelled chem- ifts to clafs it among compound fubftances ; a refiflance and oppofition were made to it, which were not manifested when the air, the earth, and the other matters reputed to be elementa- ry, were Subjected to fimilar revolutions. It Seems to me how- ever, that this analyfis is equally ftridt with that oS air. Water is decompoSed by Several proceffes j it is formed by the com- bination of oxigene and hydrogene : and we find that all the phenomena of nature and art confpire to prove the Same truths What more can be required to afford an abSolute certainty re- specting any phyfical fact ? Water is contained in bodies in a greater or lefs quantity, and may be confidered in two ftates : it is either in the flate of fim- ple mixture, or in a Stare of combination. In the firft cafe, it renders bodies humid, is perceptible to the ey^, and may be dif- engaged with the greateft facility. In the fecond, it exhibits no character which fhows that it is in a ftate of mixture, ft exifts in this form in cryftals, falts, plants, animals, Sec. It i* this water which the celebrated Bernard has called Generative Water; and of which he has made a fifth element, to diftirs j'i-Sh it Srom exhalative watrr. 112 General Properties of Water* Water, existing in a ftate of combination in bodies, concur* in imparting to them hardnefs and (ranSparency. Salts, and moft ftony cryftals, lofe their transparency when they are de- prived oS their water of cryftallization. Some bodies are indebted to water for their fixity. The acids, for example, acquire fixity only by combining with water. Under thefe various points of view, water may be confider- ed as the general cement of nature. The Stones and Salts which are deprived of it, become pulverulent; and water fa- cilitates the coagulation, re-union, and confiftence of the parti- cles of ftones, falts, &c. as we Shall See in the operations per- formed with plafters, lutes, mortar, &c. Water, when difengaged from its combinations, and in a ftate of abfolute liberty, is one of the moft confiderable agents in the operations of this globe. It bears a part in the forma- tion and decompofition of all the bodies of the mineral king- dom : it is neceffary to vegetation, and to the free exercife of moft of the functions of animal bodies ; and it haftens and facilitates the deftruction of thefe bodies as foon as they are deprived of the principle of life. For a certain time water was thought to be a fluid earth. The diftillation, trituration, and putrefaction of water, which always left an earthy refidue, afforded credit to an opinion that it was converted into earth. On this fubject, the works of Wallerius and Margraff may be confulted : but Mr. Lavoi- fier has fhewn that this earth arifes from the wear of the vef- fels ; and the celebrated Scheele has proved the identity of the nature oS this earth with that of the glafs veflels in which the operations were made. So that the opinions of the philofoph- ical world are at prefent decided in this refpect. In order to obtain accurate ideas of a fubftance fo neceffary to be known, we will confider water under its three different ftates, of folidity, fluidity, and gas. ARTICLE I. Concerning Water in the State of Ice. Ice is the natural ftate of water whenever it is deprived of a portion of that calorick with which it is combined when it ap- pears in the form of a liquid or gas. The converfion into ice is attended with feveral phenomena which feldom vary. A. The firft of all, and at the fame time the moft extraor- dinary, is a feniible production of heat at the moment in which Water in the Solid State. 1i3 the Water paffes to the folid ftate. The experiments of Mefffs. Fahrenheit, Triewald, Baume, De Ratte, leave no doubt on this luhject ; fo that the water is colder at the inftant of congela- tion than the ice itfelf. A flight agitation of the fluid facilitates its converfion into ice nearly in the fame manner as the flightefb motion very fre- quently determines the cryftallization of certain falts. This arifes, perhaps, from the circumftance, that by this means the calorick, which is interpofed between, the particles, and may oppofe itfelf to the production of the phenomena, may be ex- prefled or difengaged. In proof of this opinion, it is feen that the thermometer rifes at the very fame inftant, according to Fahrenheit. B. Frozen water occupies a larger fpace than fluid water : we are indebted to the Academy del Cimento for the proofs of this truth. In their experiments, bomb fhells, and the ftrong- eft veffels, being filled with water, were burft into pieces by the congelation of this fluid. The trunks of trees are fplit and divided with a loud noife, as foon as the fap freezes ; and fo likewife ftones are broken in pieces the moment the water with which they are impregnated paffes to the ftate of ice." C. Ice appears to be nothing more than a confufed cryftal- lization. Mr. De Mairan obferved that the needle-formed cryftals of ice unite in an angle of either fixty or one hundred and twenty degrees. Mr. Pelletier obferved, in a piece of fiftulous ice, cryftals in the form of flattened triangular prifms, terminated by two di- hedral Summits. Mr. Sage obferves, that iS a piece oS ice, which contains water in its internal parts, be broken, the water runs out, and the internal cavity is Sound to be lined with beautiful tetrahedral prifms, terminated in four-Sided prifms. Thefe prifms are often articulated and croffed. Vide M. Sage, Anales de Chirnie, torn. i. p. 77. Mr. Macquart has obferved, that when it fnows at Mofcow, and the atmofphere is not too dry, the air is obferved to be loaded with beautiful cryftallizations regularly flattened and as thin as a leaf of paper. They confift of an union of fibres which Shoot from the fame centre to form fix principal rays ; and thefe rays divide themfelves into fmall blades extremely brilliant : he obferved feveral of thefe flattened radii which were ten lines in diameter. D. When water paffes from the folid to the liquid ftate, it produces cold by the abforptio:i of a portion of heat, as is con- firmed by the fine experiments of Wilcke. This production P 1.1.4 Water in the Liquid Slate. of cold by the fufion of ice, is likewife proved by the practice of the confectioners, who fufe certain falts with ice, in order tc* produce a degree of cold below o. Ice is found in many places in great maffes, known by the name of Glacieres : certain mountains are conftantly covered with them, and the fouthern ocean abounds with them. The ice-formed by fait water affords frefh water when melted ; and in feveral northern provinces water is faid to be concentrated by froft, to collect the fait in holes in folution. I have likewife obferved, that feveral metallick falts are precipitated by expofing their Solutions to a temperature Sufficient to freeze them. The ice which was formed did not poffefs the characters of the fait which had been diffolved. Hail and fnow are nothing but modifications of ice. We may confider hail as produced by the fudden difengagement of the elaft'jk fluid, which concurs in rendering, water liquid : it is almoft always accompanied with thunder. The experiments of Mr. Quinquet have confirmed this theory.—I will here re- late a fact to which I myfelf was witnefs, at Montpelier, and of which philofophers may advantageoufly avail themfelves. On the 29th of October, 1786, four inches of water fell at Montpe- lier ; a violent explcficn of thunder, which was heard about four in the evening, and which appeared to be very near, cauf- ed a moft dreadful fhower of hail. At this inftant a druggift, who was> employed in his cellar in-preventing the mifchief oc- cafioned by the filtration of water through the wall, was highly aftonifhed'to behold that the water which came through the wall was inftantly changed into ice. He called in feveral neighbours to partake of his Surprize. I vifited the place a quarter of an hour afterwards and found ten pounds of ice at the foot of the wall; I was well affured that it could not have paffed through the wall, which did not exhibit any crack, but appeared to be in very good condition. Did the Same cauSe, which determined the formation oS hail in the atmoSphere, act equally in this cel- lar ?__I rciate the fact only, and forbear to make any conjecture; upon it. ARTICLE II. Concerning Water in the Liquid State. The natural ftate of water appears to be that of ice : but its, moft ufual ftate is that of fluidity ; and under this form it poS> Seffes certain general properties which we fhall proceed to de- fcribe. Diflillatkn of Water. i ij; The experiments of the Academy del Cimento have caufed ■;he philoSophical word to deny the leaft elasticity to water, be- cauSe it eScapcd through the pores oS balls oS metal Strongly com- prcffed, rather than yieWto preflurc. 13ut Meffrs. Zimmerman, and the abbe Mongez, have endeavoured to prove its elasticity Srom the very experiments upon which the contrary opinion has heen built*. The liquid ftate renders the Sorce of aggregation in water lefs powerSul, and it enters into combination more readily in this form. Water which flows on the Surface of our globe is never pure. Rain-water is feldom exempt from*fome mixture, asap- pears from the fine feries of experiments of the celebrated Mar- graft*. I have afcertained at Montpelier, that rain-water in ftorms is more impure than that of a gentle fhowev—that the water which falls firft is lefs pure than that which falls after feveral hours or feveral days rain—that the water which falls when the wind blows from the fea to the Southward, contains fea-Salt; whereas that which is produced by a northerly wind, does not contain a particle. Hippocrates has made Several very important observations re- specting the various qualities of water, relative to the nature of the foil, the temperature of the climate, Sec. As it is of importance to the chemift to have very pure water for feveral delicate operations, it is neceffary to point out the means which may be ufed to carry any water whatever to this degree of purity. Water is purified by diftillation. This operation is perform- ed in veffels called Alembicks. The Alembick is compofed of two pieces ; a boiler or cucurbit, and a covering, called the capi- tal or head. The water is put into the cucurbit, from which it is raifed in vapours by means of fire, and thefe vapours are condenfed by cooling the head with cold water. The condenfed vapours flow into a veffel defigned to receive them. This is called Diftilled Water ; and is pure, becauSe it has leSt behind it in the cucur- bit the Salts and other fixed principles which altered its purity. Diftillation is more Speedy and quick, in proportion as the pceffure of the air is lefs upon -the Surface of the flagnant fluid. • The experiments of Canton, to prove the coinpreffihility of water are well known, and may be feen in the Philofophical I ranfaclionj. He ir clofed water in fpheric.il glafs veflels. from which a narrow neck proceeded like that of a thermometer : the water w»s found to occupy a larger fpace when the preflurc of the atmofphere was removed i>y the air-p;uup, and a lefs fojee / practised, by making uSe of a bottle to which he adapted * moiftened bladder. 2. By diftillation of the fame fluid.—Thefe two firft meth- ods are not accurate. ^ 3. The proceSs indicated by Mr. Gioanetti, confifts in pre- cipitating the carbonick acid by means oS lime-water, weighing the precipitate, and deducting thirteen thirty-Second parts Sor the proportion of carbonick acid ; it having been deduced from analyfis, by this celebrated phyfician, that thirty-two parts of carbonate of lime contain Seventeen lime, two water, and thir- teen acid. This fubftance is an acid, as is proved—1. BecauSe tincture of turnSole, agitated in a bottle filled with this gas, becomes red. 2. Ammoniack, or volatile alkali, poured into a veffel filled with this gas, is neutralized. 3. Water impregnated with this gas is ftrongly Sub-acid. 4. It neutralizes alkalis, and cauSes them to cryftallize. It remains at prefent to examine the properties of this acid gas. A. It is unfit for refpiration. Hiflory informs us that two flaves whom Tiberius caufed to defcend into the Grotto de! Cano, were immediately ftifled ; and two criminals that Peter de Toledo caufed to be fhut in there, fuffered the fame fate. The abbe Nollet, who had the courage to refpire the vapour, perceived a fuffocating fenfation, and a flight degree of acidity, which produced coughing and Sneezing. Pilatre de Rofier who preSents himSelS to our notice on all occafions wherein danger was to be Saced, cauSed himSelS to be Saftened by cords fixed under his arms, and defeended into the gaSeous atmof- phere of a back oS beer in Sermentation. He had Scarcely en- tered into the mephitis beSore flight prickings obliged him to Shut his eyes ; a violent Suffocation prevented him Srom refpir- ing ; he felt a giddineSs, accompanied with thoSe noifes which characterize the apoplexy : and when he was drawn up, his fight remained dim Sor Several minutes; the blood had filled the jugulars; his countenance had become purple , and he neither heard nor Spoke but with great difficulty : all theSe Symptoms, however, disappeared by degrees. It is this gas which produces the many unhappy accidents at the opening oS cellars, in places where wine, cider, or beer are Suffered to Serment. Birds plunged into the carbonick acid gas, Suddenly perifh. The famous Lake of Averno, where Virgil placed the entrance of hell, exhales fo large a quantity of car- bonick acid, that birds cannot fly over it with impunity. When the waters of Poulidou of Perols vs dry, fuch birds as attempt *3^ General Properties and to quench their thirft in the clefts, are enveloped in the mephit«« ick vapour and die. Frogs, plunged in an atmofphere of carbonick acid, live from forty to Sixty minutes, by fufpending their reSpiration. InSefts are rendered torpid aSter a certain time oS remaining in this air; but they reSume their livelineSs the moment they are expoSed to the free air. m Bergmann pretended that this acid Suffocates by extinguish- ing irritability: he founds his opinion upon the circumftance of his having taken out the heart of an animal which had died in the carbonick acid, before it was cold, and it exhibited no Sign of irritability. The chevalier Landriani has proceeded ftill Surther: for he affirms that this gas extinguifhes irritability, even when applied to the fkin ; and has afl'erted that, by tying a bladder Sull cf this gas to the neck of a fowl, in fuch a manner that the head only of the animal was in the open air, and the whole body enveloped in the bladder, the fowl immediately perifhed. The abbe Fontana has repeated and varied this experiment on Several animals, none of which died. The count Morrozzo published experiments made in the pref- ence of Dr. Cigna; the refults of which appear to invalidate the confequences of the celebrated Bergmann : but it is to be obferved, that the chemift of Turin caufed his animals to die only in air vitiated by the death of another animal; and that in this circumftance the nitrogene gas predominates.—See the Journal de Phyfique, torn. xxv. p. 112. B. The carbonick acid is improper for vegetation. Dr. Prieltley having kept the roots of Several plants in water impreg- nated with the Carbonick acid, obServed that they all perifhed ; and in thoSe inftances where plants are obSarved to vegetate in water or in air which contains this gas, the quantity of gas is very Small. Mr. Senebier has even obServed, that plants which are Suffer- ed to grow in water Slightly acidulated with this gas emit a much larger quantity of oxigenous gas ; becaufe, in this cafe, the acid is decompofed, the carbonaceous principle combines and is fixed in the vegetable, while the oxigene is thrown off. I have obferved that thofe fungi which are formed in fubrer- raneous places, are almoft totally refolved into carbonick acid; but if thefe vegetables be gradually expofed to the action of light, the proportion of acid diminishes; while that of the coaly principle augments, and the vegetable becomes coloured. I have purfued thefe experiments with the greateft care in a coal mine. Habitudes of Carbonick Acid. 137 C. The carbonick acid is eafily diffolved in water. Water impregnated with this acid poffeffes very valuable medicinal qualities ; and feveral apparatus have been fucceffively invented to facilitate this mixture. The apparatus of Nooth, improved by Parker and Magellan, is one of the moft ingenious. On this fubject the Encyclopedic Methodique may be confulted, ar- ticle Acide Mephitique. The natural acidulous mineral waters do not differ from, thefe, excepting in conSequence of their holding other princi- ples in folution j and they may be perfeftly imitated when their analyfis is well known. It is abfurd to think that art is incapa- ble of imitating nature in the compofition oS mineral waters. It muft be admitted that the proceffes of nature are abfolutely unknown to us, in all the operations which relate to life ; and we cannot flatter ourfelves with the hope of imitating her in thefe circumftances. But when the queftion relates to an ope- ration purely mechanical, or confiding of the folution of certain known principles in water, we can and ought to perform it even ftill better, as we have the power of varying the dofes, and pro- portioning the efficacy of any artificial mineral water to the purpofes to which it is intended to be applied. D. The carbonick acid gas is heavier than common air. The proportion between thefe two airs in weight, according to Mr. Kirwan, is 45,69 to 68,74. The proportion, according to the experiments of Mr. Lavoifier, is 48,81 to 69,50. This confiderable weight caufes it to occupy the loweft Situ- ations and even gives it the property of being poured out from one veffel to another, fo as to difplace the atmoSpherick air. This truly curious phenomenon Was obferved by Mr. De Sauva- ges, as may be Seen in his Differtation upon air, which was crowned in MarSeilles, in 1750. It appears to be proved, by Sufficient experiments, that the carbonick acid is a combination of carbone, or pure charcoal, and oxigene. 1. The oxides of mercury, when diftilled, are reducible without addition, and afford only oxigenous gas ; but if a fmall quantity of charcoal be mixed with the oxide, the product which comes over confifts of carbonick gas only, and the weight of the charcoal is diminifhed. 2. If well-made charcoal be ignited, and plunged into a vef- fel filled with oxigenous gas, and the veffel be inftantly clofed, the charcoal burns rapidly, and at laft goes out: the produa in this experiment is carbonick acid, which may be feparated by the known proceffes j the remainder is a fmall quantity of oxi- genous gas, which may be converted into carbonick acid by the fame treatment. S *3& Carbonate of Pot-Aft. In thefe experiments I See nothing but charcoal and oxigenous- gas; and the conSequence deduced is fimple and natural. The proportion of charcoal is to that of oxigene as 12,0288 to 56,687. When the carbonick acid, in Some caSes, is obtained by burn- ing hydrogenous gas, it ariSes Srom carbone held in Solution in this gas. The carbone may even be diffolved in hydrogenous gas, by expofing it to the Socus of the burning mirror in the mercurial apparatus, under a glafs veffel filled with this gas. The hydrogenous gas which is extraded from a mixture of ful- phurick acid and iron, holds more or lefs of charcoal in folution; becauSe iron itSelf contains this fubftance in a greater or lefs quantity, as is afcertained by the fine experiments of Meffrs. Berthollet, Monge, and Vander Monde. The alkalis, fuch as we ufually meet with them, contain car- bonick acid ; and it is this acid which modifies them, and dimin- ifhes their energy, at the fame time that it communicates to them the property of effervefcing. We may therefore confider alka- lis as carbonates with excefs of alkali; and it is eafy to Saturate this Superabundant alkali,-and to form true cryftallizable neutral falts. ARTICLE I. Carbonate of Pot-Afh. The carbonate of pot-afh was formerly diftinguifhed by tha* name of Cretaceous Tartar. The method of caufing oil of tar- tar to cryftallize, has long been known. Bonhius and Montefc haveSucceffively Shewn theSe proceffes: but the fimpleft confift* in expofing an alkaline folution in an atmofphere of the acid gas which is difengaged in the vinous fermentation ; the alkali becomes Saturated, and Sorms tetrahedral priSmatick cryftals ter- minated by very Short Sour-Sided pyramids. I have Several times obtained thoSe cryftals in the Sorm of quadrangular priSms, with their extremities cut off flantwiSe» This neutral Salt no longer poffeffes the urinous tafte oS the alkali, but exhibits the penetrating tafte of neutral falts, and may be employed in medicine with the greateft fucceSs. I have been a witneSs to its being taken in the doSe of one dram (groSs) without the leaft inconvenience. This Salt poffeffes an advantage beyond the fait of tartar, irf being lefs cauftick, and always of the fame virtue. Carbonate of Ammoniack. *39 It contains, according to the analyfis cf Bergmann, twenty parts acid, forty-eight alkali, and thirty-two water, in the quintal. It does not attraft the humidity of the air. I have preferved fome of it for feveral years in a capfule, without any appearance joi alteration. The carbonate oS pot-afh is decompoSed by filex in a Sufficient heat, which occafions a confiderable boiling or ebullition. The refidue is glaSs, in which the alkali is in the cauftick ftate. Lime decompofes the carbonate, by uniting to the acid ; and acids produce the Same effea, by combining with the alkaline baSes. ARTICLE II. Carbonate of Soda. The denominations of Aeriated Mineral Alkali, Cretaceous Soda, &o have been fucceffively given to this kind of carbonate. The mineral alkali, in its natural ftate, contains a greater quantity of carbonick acid than the vegetable ; and nothing more is neceffary than to diffolve it, and duly evaporate the water, in .order to obtain it in cryftals. TheSe cryftals are ufually rhomboidal oaahedrons and Some- times have the Sorm oS rhomboidal laminae, applied obliquely oue upon the other, So that they reSemble tiles. This carbonate effloreSces in the air. One hundred parts contain Sixteen parts acid, twenty .alkali, and fixty-Sour water. The affinity of its bafis with filex is Stronger than that of the carbonate oS pot-afh ; in conSequence oS which, the vitrification it produces is more quick and eaSy. Lime and the acids decompoSe it, with the Same phenomena which we have obferved at the article carbonate of Pot-afh. ARTICLE HI. Carbonate of Ammoniack. This fait has been generally known by the name of Concrete Volatile Alkali. It has likewife been diftinguifhed by that of ,Cretaceous Volatile Alkali, &c. It may be obtained by diftillation from many animal fubftan- ces. Tobacco affords, likewife, a large proportion ; but almoft the whole of that which is employed in the arts, and in medi- cine, is formed by the direct combination of the carbonick acid and ammoniack, or volatile alkali. This combination may be J4» Production of the Sulphurick (effected-—i. By paffing the carbonick acid through ammoniack, or the pure volatile alkali in Solution. 2. By expofing ammo- j&iack in an atmoSphere of carbonick acid gas. 3. By decom- pofing the muriate of ammoniack by the neutral Salts which con- tain this acid, Such as* the carbonate oS lime or common chalk. For this purpoSe, white chalk is taken, and very accurately dri- ed ; and then mixed with equal parts of muriate of ammoniack or common fal ammoniack, in fine ppwder. This mixture is. put into a retort, and diftilled ; the ammoniack and the carbon- ick acid being difengaged from their bafes, and reduced into vapours, combine together, and are depofited on the fides of the receiver, where they form a Stratum more or lefs thick. The cryftallization of this carbonate appeared to me to be fhat of a four-fided prifm, terminated by a dihedral Summit. The carbonate has leSs Smell than the ammoniack ; it is very foluble in water. Cold water diffolves its own weight of this fait, at the temperature of fixty degrees of Fahrenheit. One hundred grains of this fait contain forty-five parts acid, forty-three alkali, and twelve water, according to Bergmann. Moft acids decompoSe it, and diSplace the carbonick acuh CHAPTER II. Concerning the Sulphurick Acid. SULPHUR, like every other combuftible fubftance, cannol be burnt but by virtue of the oxigenous gas which combines with it. The moft ufual phenomena which accompany this combuftr ion are, a blue flame, a whitifh and Suffocating vapour, and a flrong, penetrating, and diSagreeable Smell. The refuks of this combination vary according to the pror portion in which thefe two principles enter into this fame com- bination. The fulphureous or the fulphurick acid may be at pleaSure obtained from fublimed Sulphur, or Srom crude Sulphur, ac-; cordingly as a greater or leSs quantity of oxigene is combined, with the Sulphur, by means of combuftion. When the current of air which maintains the combuftion is rapid, the fulphur is carried, and depofited without any appar- ent alteration, into the internal part of the leaden chambers in which the oil of vitriol is made. If the current of air be ren- dered more moderate, the combination is fomewhat more ac- curate ; the fulphur is partly changed, and is depofited in a pellicle upon the furface of the water. This pellicle is flexible cr Vitriolick Acid, 141 Jike a flcin, and may be handled and turned over in the fame manner. IS the current be ftill leSs rapid, and the air be Suf- fered to have a fufficient time to form an accurate combination with the fulphur, the refult is Sulphureous acid ; which acid preServes its gaSeous form at the temperature of the atmofphere, and may become liquid like water by the application of cold, according to the fine experiments oS Mr. Monge. IS the com- buftion be ftill flower, and the air be Suffered to digeft upon the fulphur a longer time and with greater accuracy, the reSult is fulphurick acid : this laft combination may be Sacilitated by the mixture oS Saltpetre becauSe this Subftance furniShes oxigene very abundantly. Numerous experiments which I have made in my manufactory, %o economize the Saltpetre employed in the Sabrication of oil of vitriol, have feveral times exhibited the refults here mentioned. All the proceffes which are capable of being adapted for ex-- traaing the Sulphurick acid, 3re reducible to—1. The extrac- tion of it Srom Subftances which contain it. 2. Its direa for- mation by the combination oS Sulphur and oxigene. In the firft caSe, the Sulphures, or vitriolick Salts oS iron, cop- per, or zinc, and even thoSe whoSe baSes are clay and lime, ac- cording to Newman and Margraff, may be expoSed to diftilla* tion. But theSe expenfive proceffes are not very eafy to be parried into execution ; and accordingly they have been aban- doned, to make room for others of greater Simplicity. In the Second caSe, the oxigene may be preSented to the Sul- phur in two forms ; either in the State pS gas, or in the con- crete ftate. 1. The combuftion of fulphur by oxigenous gas, is perform- ed in large chambers lined with lead. The combuftion is fa- cilitated by mixing about one eighth of a nitrate of pot-afh with the fulphur. The acid vapours which fill the chamber are precipitated againft its fides, and the condensation is Sacil- itated by a ftratum oS water diSpoSed on the bottom oS the chamber. In Some manuSaaories in Holland, this combuftion is performed in large glaSs balloons with large mouths, and the vapours are precipitated upon water placed at the bottom. In both caSes, when the water is Sufficiently impregnated with acid, it is concentrated in leaden boilers, and reaified in glaSs retorts, to render it white, and to concentrate it Sufficient- ly for the purpoSes oS trade. The acid, when oS a due ftrength, indicates Sixty-fix degrees, according to the aerometer of Mr. Baume ; and when it has not been carried to this degree, it is unfit for moft of the ufes for which it is intended. It cannot, for example^ be employed in difibh/ing indigo ; for the fm^l 14* Neutral and Congealed Sulphurick Acid. quantity of nitrick acid which it contains, unites with the blue of the indigo, and forms a green colour. I have ascertained this phenomenon by very accurate experiments ; and I have been a witneSs to the failing oS colours, and the loSs of fluffs,, in conSequence of the imperfection of the acid. 2. When the oxigene in the concrete ftate is prefented to the fulphur, it is then in combination with other bodies, which if abandons to unite with this laft. This happens when the ni- trick acid is diftilled from fulphur. Forty-eight ounces oS this acid, at thirty-fix degrees, diftilled from two ounces oS Sulphur, afforded near four ounces of good fulphurick acid. This fact: was known to Matte Lafaveur : but I pointed out all the phe- nomena and circumftances of the operation in 1781. Sulphur may likewife be converted into fulphurick acid by means of the oxigenated muriatick acid.—Encyclopedic Metho- dique, torn. i. p. 370. The fulphurick acid which is found difengaged in fome places in Italy, appears likewife to arife from the combuftion of fuL- phur. BaJdaSfari has obServed it in this ftate in a hollow grotto, in the midft oS a maSs oS incruftations depofited by the baths of Saint Philip, in TuScany. He afferts that a Sulphureous vapour continually ariSes in this grotto. He likewiSe Sound Sulphurer ous and vitriolick effervefences at St. Albino, near mount Pulci- ano, and at the lakes of Travale, where he obferved the branch- es of a tree covered with concretions of fulphur and the oil of vitriol.—Journal dePhyfiquc, t. vii. p. 395. O. Vandelli relates that, in the environs of Sienna and Viter- bo, fulphurick acid is fome times found diffolved in water. Mr. (the commander)De Dolomeu affirms that he Sound it pure and cryftallized in a grotto of mount Etna, from which fulphur was formerly obtained. According to a firft experiment of Mr. Berthollet, fixty-nine parts of fulphur with thirty-one parts of oxigene formed one hundred parts of fulphurick acid ; and according to a fecond experiment, feventy-two of fulphur and twenty-eight of oxigene formed one hundred parts of dry acid. The various degrees of concentration of the fulphurick acid have caufed it to be diftinguifhed by different names, under which it is known in commerce. Hence the denominations of Spirit of Vitriol, Oil of Vitriol, and Glacial Oil of Vitriol, to exprefs its degrees of concentration. The fulphurick acid is capable of paffing to the concrete ftate by the impreffion of intenSe cold. This congelation is a phe- nomenon long Since known. Cunckle and Bohn have Spoken of it ; and Boerhaave Says, expreSsly, " Oleum vitrioli, lummarte Characters of Sulphurick Acid. 14J puriffimum, fummo frigore hiberno in glebas folidefeit perfpicu* as ; Sed, ftatim ac acuties frigoris retunditor, liquefcit et dif- fluit."—We are indebted to the Duke D'Ayen for fome very valuable experiments upon the congelation of this acid ; and Mr. De Morveau repeated them with equal fucceSs in 1782, and proved that this congelation may be effeaed at a degree of eold confiderably lefs than what had been mentioned.* I have already Several times obtained beautiSul cryftals oS Sul- phurick acid in flattened hexahedral priSms, terminated by an hexahedral pyramid ; and my experiments have enabled me to conclude—1. That the very concentrated acid cryftallizes more difficultly than that whoSe denfity lies between fixty-three and Sixty-five. 2. That the proper degree oS cold is from 1 to 3 degrees below o of Reaumur. The detail of my experiments maybe feen in the volume of the Academy of Sciences of Paris for the year 1784. The charaaers of the fulphurick acid are the following : 1. It is unauous and fat to the touch, which has occafioned it to obtain the very improper name of Oil of Vitriol. 2. It weighs one ounce and feven gros in a bottle containing One ounce of diftilled water. 3. It produces heat, when mixed with water, to fuch a de- gree as to exceed that of boiling water. If one end of a tube of glafs be clofed, and water poured into it, and the clofed end of this tube be plunged into water, the water in the tube may be made to boil by pouring fulphurick acid into the external water which Surrounds the tube. 4. It feizes with great avidity all inflammable fubftances ; and it is blackened and decompofed by this combination. Stahl fuppofed the fulphurick acid to be the univerfal acid. He founded this opinion more efpecially upon the circumftance, that cloths Soaked in a Solution oS alkali and expoSed to the air, attraaed an acid which combined with the alkali ; and formed a neutral Salt, by him SuppoSed to be oS the nature of fulphate of pot-afh, or vitriolated tartar. Subsequent and more accurate experiments have Shewn that this aerial acid was the carbonick 5 and the preSent ftate oS our knowledge is Such as permits us ftill leSs than ever to beiieve in the exiftence of an univerfal acid. * Sec alfo the experiments nf Mr. K!er, and the late experiment'; of Mr, C.tvcmii'.li 011 tl»« congelation of acid*, in tue Philofophica! Traductions. M4 Sulphate of Soda* ARTICLE L Sulphate of Pot-afh. The fulphate of pot-affi is defcribed indifferently under the names of Arcanum Duplicatum, Sal de Duobus, Vitriolated Tartar, Vitriol of Pot-afh, &c. ... This fait cryftallizes in hexahedral prifms, terminating iri hexahedral pyramids, with triangular faces. It has a lively and penetrating tafte, and melts difficultly in the mouth. . . It depreciates on hot coals, becomes red-hot before it iuiesj and is volatilized without decompofition. It is foluble in fixteen parts of cold water, at the tempera- ture of 60 degrees of Fahrenheit; and boiling water diffolves one fifth of its weight. 100 grains contain 30,21 acid, 64,61 alkali, and 5,18 water. Moft of the fulphate of pot-afh ufed in Medicine is formed by the direa combination of the fulphurick acid and pot-afh, or the vegetable alkali : but that which is met with in commerce is produced in the diftillation of aqua fortis, by the fulphurick acid ; this has the form of beautiful cryftals, and is fold in the Comtat Venaifin at forty or fifty livres the_quintal. The anal- yfis of tobacco has likewife afforded me this fulphate. Mr. Baume proved to the Academy in 1760, that the nitrick acid, affifted by heat, is capable of decompofing the fulphate of pot-afh. Mr. Cornette aSterwards Shewed that the muriatick acid poffeffes the Same virtue ; and I Shewed in 1780, that this acid may be diSplaced by the nitrick acid, without the affiftance of heat ; though the fulphurick acid refumes its place when the folution is concentrated by heat. ARTICLE II. Sulphate of Soda. This combination of the fulphurick acid and foda is ftilf known under the names of Glauber's Salt, Sal Admirabile, Vitriol of Soda, &c. This Salt cryftallizes in reaangular oaa- hedrons, oS a priSmatick or cuneiform figure, of which the two pyramids are truncated near their bafis. ' It has a very bitter tafte, and eafily diffolves in the mouth. It fwells up upon heated coals, and boils, in confequence of the d'nTmation of its water of cryftallization. After this water ha» Sulphate of Ammoniack. jap Wen difperfed, there remains only a white powder, difficult of fufion, which is volatilized without decomposition by a ftrong heat. By expoSure to the air, it efferveSces, lofes its transparency, and is reduced to a fine powder. Three parts oS water at 60 degrees of Fahrenheit's thermom- eter, diffolved one part of this fait; but boiling water diffolves its own weight. 100 grains of fulphate of foda contain 14 acid, 22 alkali and 64 water. It is formed by the direa combination of the two principles which contain it; but the tamarix gallic?, which grows on the fea coafts, contains fo large a quantity, that it may be extraaed to advantage. Nothing more is neceffary for this purpofe, than to burn the plant, and Hxivjate the afhes. That fait which is fold in the fouth of France, in fine cryftals, is prepared in this manner. It is very pure, and the price does not exceed thirty or thirty-five livres the quintal. This Sulphate is likewiSe Sorm- ed in our laboratories when we decompose the muriate of foda, or common Salt* by the Sulphurick acid. Pot-afh diffolved by heat in a folution of fulphate of foda, precipitates the foda, and takes its place. See my Chemical Memoirs. ARTICLE III. Sulphate of Ammoniack. The Sulphate oS Ammoniack, commonly known by the name ©S Glaubers Secret Ammoniacal Salt, is very bitter. It cryftallizes in long flattened priSms with fix fides, termi- nated by fix-Sided pyram ids. It cannot be obtained in well-formed cryftals but by infenfi- ble evaporation. It Slightly attraas the humidity of the air Jt liquefies by a gentle heat, and riSes over a moderate fire. Two parts of cold water diffolve one of this fait; and boiling water diffolves its own weight, according to Fourcroy. The fixed alkalis, barytes, and lime, difengage the ammoniack from it. The nitrick and muriatick acids diSengagethe Sulphurick acid. The different Subftances of which we have treated are of con- siderable uSe in the arts and medicine. T 146 Acid of Nitre, or Nitrick Acid. The fulphureous acid is employed in whitening filk, and giv- ing it a degree of luftre. Stahl had even combined it with al- kali, and formed the fait fo' well known under the name of Stahl's Sulphureous Salt. This combination paffes quickly to the ftate of Sulphate, if it be left expofed to the air; as it fpee- dily abforbs the oxigene which is wanting for that purpofe. The principal uSe oS the Sulphurick acid is in dying, in which art it Serves to diffolve indigo, and carry it in a ftate of extreme divifion upon the ftuffs to be died ; it is likewife ufed by the manufaaurers of Indiens, or filk and Stuff mixtures, to carry off the preparation oS theSe goods, wherein lime is uSed. The a chemift makes great uSe of this acid in his analyfes ; and to' feparate other acids from their combination, fuch as the carbon- ick, the nitrick, and the muriatick acids. The fulphate oS pot-affi is known in medicine as an altera- tive, and is uSed in caSes oS laaeous coagulations. It is given in the doSe of a Sew grains, and is even purgative in a greater doSe. The Sulphate of Soda is an effeaual purgative in the dofe of from Sour to eight gros, or drams. For this purpoSe it is dif- folved in a pint of water. CHAPTER IIL Concerning the Nitrick Acid. T1TE nitrick acid, called Aqua Fortis in commerce, is lighter' rtian the Sulphurick. It uSually has a yellow colour, a ftrong and diSagreeable Smell, and emits red vapours. It gives a yel- low colour to the Skin, to filk, and to almoft all animal Subftan-' ces with which it may come in contaa. It diffolves and fpeed- ily corrodes iron, copper, zinc, &c. with the efcape oS a cloud of red vapours during the whole time its aaion lafts. It entire- ly deftroys the colour of violets, which it reddens. It unites to water with facility ; and the mixture affumes a green colour, which difappears when ftill further diluted. This acid has been no where found in a difengaged ftate. It always exifts in a ftate of combination j and it is from thefe combinations that the art of chemiftry extraas it, to apply to cur ufes. The nitrick of pot-afh, or common nitre, is the com- bination which is beft known, and is likewife that from which we uSually extraa the nitrick acid. Acid of Nitrs, or Nitrick Acid. *47 The procefs ufed in commerce to make»aqua fortis, confifts fo mixing one part of faltpetre with two or three parts of red bolar earth. This mixture is put into coated retorts, difpoSed in a gallery or long furnace, to each of which is adapted a receiver. The firft vapour which arifes in the diftillation is nothing but water, which is Suffered to eScape at the place oS junaure, be- fore the luting : and when the red vapours begin to appear, the phlegm which is condenfed in the receiver is poured out; and the receiver, being replaced, is carefully luted to the neck oS the retort. The vapours which are condenfed, Sorm at firft a greeniffi liquor : this colour disappears infenfibly, and is replac- ed by another which is more or leSs yellow. Some chemifts, more especially Mr. Baume, were oS opinion that the earth aa' ed upon the Saltpetre by virtue of the fulphurick acid it contains. But not to mention that this principle does not exift in all the earths made ufe of, as Meffrs. Macquer, De Morveau, and Scheele have proved, we know that pulverized flints equally produce the decompofition of faltpetre. I am therefore of opinion that the effect oS theSe earths upon the Salt ought to be referred to the very evident affinity oS the alkali to the filex, which is a principal component part; and more eSpecially to the flight degree oS adhefion which exifts between the conftit- uent principles of nitrate of ppt-afh. We decompofe faltpetre in our laboratories by means of the fulphurick acid. Very pure nitrate of pot-afh is taken, and in- troduced into a tubulated retort, placed in a fand bath, with 4 receiver adapted. All the places of junaion are carefully luted ; and as much fulphurick acid as amounts to half the weight of the fait is poured through the tubulure ; and the dif- tillation is proceeded upon. Care is taken to fit a tube into the tubulure oS the receiver; the other end of which is plun- ged into water, to condenfe the vapours, and to remove all fear of an explofion. Inftead of employing the fulphurick acid, we may fubftitute the Sulphate oSiron, and mix it with Saltpetre in equal parts. In this caSe, the refidue oSthe diftillation, when well wafhed" forms the mild earth of vitriol made ufe of to polifh glafs. Stahl and Kunckel have Spoken oS a very penetrating aqua fortis, oS a blue colour, obtained by the diftillation of nitre with arfenick. Whatever precaution is taken in the purification of the falt- petre, and however great the attention may be which is bellow- ed upon its diftillation, the nitrick acid is always impregnated with Some Soreign acid, either the Sulphurick or muriatick, from which it requires to be purified. It is cleared of the firft by re- 148 Properties and Comp$nent diftilling it upon vefy pure faltpetre, which retains the fmall quantity of fulphurick acid that may exift in the mixture. It is deprived of the fecond by pouring into it a few drops of a folu- tion of nitrate of filver. The muriatiek acid combines with the filver, and is precipitated with it in the Sorm oS an inSolu- ble Salt. The fluid is then Suffered to remain at reft, and is afterwards decanted from the precipitate or depofition. This acid, So purified, is known under the name of Aqua Fortis for Parting, Precipitated Nitrous Acid, Pure Nitrick Acid, &c. Stahl had confidered the nitrick acid as a modification of tha fulphurick, produced by its combination with an inflammable principle. This opinion has been fupported by feveral new faas, in a differtation of Mr. PietSfi, crowned by the Academy of Berlin in 1749. m The experiments of the celebrated Hales led him ftill nearer to this conclufion, as his manipulations were fuccefiiyely em- ployed upon the two conftituent principles of the nitrick acid. This celebrated philofopher had obtained ninety cubick inches of air from half a cubick inch of nitre ; and he proceeded no further in his conclusions, than to affert that this air is the prin- cipal caufe of the explofions of nitre. The fame philofopher relates that the pyrites of Walton treated with equal quantities the fpirt of nitre and water, pro- duce an air, which has the property of abforbing the frefh air which may be made to enter the veffel. This great man there* fore extracted fucceffiyely the two principles of the nitrick acid; and thefe capital experiments put Dr. Prieftley in the road to the discoveries he has Since made. It was not however until the year 1776, that the analyfis1 of the nitrick acid was well known. Mr. Lavoifier, by diltilling this acid from mercury, and receiving the feveral produas in the pneumato-chemical apparatus, has proved that the nitrick acid, whofe fpecifick gravity is to that of diftilled water as 131607 to 100000, contains-— oz. gros. grains. Nitrous gas 1 7 51^' Oxigenous gas 17 7^ Water 13 ~- — ~ By combing thefe three principles together the decompofed acid was regenerated. The aaion of the nitrick acid on moft inflammable matters, confifts in nothing more than a continual decompofition of thii acid. If the nitrick acid be poured upon iron, copper, or zinc, thefe metals are inftantly attacked with a ftrqng effervefence ; and a Parts of Nitrick Acid. *49 ponfiderable difengagement of vapours takes place, which be- come of a red colour by their combination with the atmofpher- ick air, but which may be retained and colfeaed in a ftate of gas in the hydro-pneumatick apparatus. In all thefe cafes the metals- are itrongly oxided. The nitrick acid, when mixed with oils, renders them thick and black, converts them into charcoal, or inflames them, ac- cordingly as the acid is more or lefs concentrated, or in a greatr er or lefs quantity. If very concentrated nitrick acid be put into an apothecary's phial, and be poured upon charcoal in an impalpable powder, and very dry, it fets it on fire inftantly, at the fame tjme that carbonick acid and nitrogene gas are difengaged. The various acids which are obtained by the digeftion of the nitrick acid on certain fubftances, fuch as the oxalick acid, or acid of fugar, the arfenical acid, &c. owe their exiftence merely to the decompofition of the nitrick acid, the oxigene of which is fixed in combination with the bodies upon which the acid is diftilled. The facility with which this acid is decompofed, renders it one of the moft aaive becaufe the aaion of acids upon moft bodies is a confequence of their own proper decom- pofition. ' The charaaer6 of nitrous gas, which is extraaed by the de- compofition of the acid, are—i. It is invifible, or perfeaiy transparent. 2. Its Specifick gravity is rather leSs than that of atmofpherical air. 3. It is unfit Sor reSpiration, though the ab- be Fontana pretends1 that he refpired it without danger. 4. It iioes not maintain combuftion. 5. It is not acid, according to the experiments of the Duke de Chaulnes. 6. It combines with oxigene, and reproduces the nitrick acid. but what is the nature of this nitrous gas ? It was at firft pretended that it confifts oS the nitrick acid Saturated with phlo- gifton. This Syftem ought to have been abandoned as Soon as it was proved that the nitrick acid depofited its oxigene upon the bodies on which it acted ; and that the nitrous gas was lefs in weight than the acid made ufe of. A capital experiment of Mr. Cavendifh has thrown the greateft light on the fubjea. This chemift having introduced into a tube of glafs feven parts of oxigenous gas obtained without nitrous acid, and three parts of nitrogene gas ; cr, by eftimating thefe quantities in weight, ten pahs of nitrogene to twenty-fix oS oxigene—and having cauSed the elearick Spark to pafs through this mixture, perceived that its volume or bulk was greatly diminished, and fucceeded in converting it into nitrick acid. It may be prefumed, from his experiment, that the acid, is a combination of feven parts of cxi- IS? Properties and Component gene, and three of nitrogene. Thefe proportions conftitute the1 ordinary nitrick acid ; but when a portion of its oxigene is taken away, it paffes to the ftate of nitrous gas ; fo that uitrous gas is a combination oS nitrogene gas, with a Small quantity of oxigene. Nitrous gas may be decompofed by expofing it to a Solution of the fulphure oS pot-afh, or hepar of fulphur : the oxigene gas unites to the Sulphur, and forms Sulphurick acid, while the nitro- gene gas remains behind in a ftate oS purity. Nitrous gas may likewiSe be decompoSed by means of py- rophorus, which burns in this air, and abSorbs the oxigenous gas. The Slearick Spark has likewiSe the property of decompofing nitrous gas. Mr. Van Marum has obServed that three cubick' inches of the nitrous gas are reduced by elearicity to one cubick inch and three quarters j and that this refidue no longer poS- fefled any property of nitrous gas. Laftly, according to the ex- periments of Mr. Lavoifier, one hundred grains oS nitrous gas contain thirty-two parts nitrogene, and lixty-eight parts oxi- gene : according to the Same chemift, one hundred grains oS ni- trick acid contain Seventy-nine and a half oxigene and twenty and a half nitrogene ; and this is the reafon why nitrous gas fhould be employed in a lefs portion than nitrpgene gas, to com- bine with the oxigene gas, and form the nitrick acid. Thefe ideas upon the compofition of the nitrous acid appear to be confirmed by the repeated proofs we now have of the ne- ceflity of caufing fubftances, which afford much nitrogene gas, to be prefented to the oxigene gas, in order to obtain nitrick acid. The feveral ftates of the nitrick acid may be clearly explain- ed acording to this theory:—i. The fuming nitrous acid is that in which the oxigene does not exift in a fufficient proportion ; and we may render the whiteft and moft Saturated nitrick acid fuming and ruddy, by depriving it of a part of its oxigene by means of metals, oils, inflammable fubftances, &c. or even by difengaging the oxigene by the fimple expofition of the acid to the light of the fun, according to the valuable experiments of Mr. Berthollet. The property which nitrous gas poffeffed of abforbing oxi- gene to form the nitrick acid, has caufed it to be employed to determine the proportion of oxigene in the compofition which forms our atmofphere. The abbe Fontana has conflruaed on thefe principles, an ingenious eudiometer, the description and manner of ufing which may be feen in the firft volume of Dr. Ingenhoufz's Experiments upon Vegetables. Parts of Nitrick Acid. l cl Mr. Berthollet has very juftly obferved, that this eudiometer Is inaccurate, or productive of deception—i. Becaufe it is difficult to obtain nitrous gas conftantly formed of the fame pro- protions of nitrogene gas and oxigene; for they vary, not only according to the nature of the fubftances upon which the ni- trick acid is decompofed, but likewiSe accordingly as the Solu- tion of any given fubftance by the acid is made with greater or lefs rapidity. If the acid be decompofed upon a volatile oil, noth- thing but nitrogene gas can be obtained ; if the acid aa upon iron, and it be much concentrated, nitrogene gas only will be obtained, as I have obferved, &c. 2. The nitrick acid which is formed by the union of nitrous gas and oxigene, diffolves a greater or lefs quantity of nitrous gas, according to the temper- ature, the quality of the air which is tried, the fize of the eudi- ometer, &c. fo that the diminution varies in proportion to the greater or lefs quantity of nitrous gas obtained by the nitrick acid which is formed^ consequently the diminution ought td be greater in winter than in Summer, &e According to the experiments of Mr. Lavoifier, four parts of oxigenous gas are fufficient to Saturate Seven parts and one third OS nitrous gas ; whereas it is Sound that nearly Sixteen parts of atmofpherick air are required to produce the fame ef- fea : whence this celebrated chemift has concluded, that the, air of the atmofphere does not in general contain more than one fourth of oxigenous or refpirable gas. Repeated experiments at Montpellier, upon the Same principle, have convinced me that twelve or thirteen parts of atmofpherick air are conftantly fufficient to Saturate feven parts and one third of nitrous gas. Thefe experiments fhew, to a certain degree of accuracy, the proportion in which vital air exifts in the air which we refpire ; but they do not give us any inSormation reSpeaing the noxious gafes, which when mixed with the atmoSpherick air, alter if, and render it unwholeSome. This observation very much cur- tails the uSe'of this inftrument. The combination of the oxigenous and nitrous gafes alway9 leaves an aeriform refidue, which Mr. Lavoifier eftimated at about one thirty-fourth of the whole volume : it ariSes from the mixture of the foreign gafeous fubftances, which more or lefs affea the purity of the gafes made uSe of. tJJ* Nitrate cf Pot-Afh, or Nitre. ARTICLE I. Nitrate oS Pot-afh. The nitrick acid, combined with pcr-afh, Sorms the Salt (c Well known under the names of Nitre, Saltpetre, Nitre of pot- afh, &c. This neutral fait is rarely the produa of any direa combi- nation of its two conftituent parts. It is found ready formed in certain places; and in this manner it is that the whole of the nitre employed in the arts is obtained. In the Indies,, it efftorefes on the furface of uncultivated grounds. The inhabitants lixiviate thefe earths with water; which they afterwards boil and cryftallize in earthen pots, Mr. Dombey has obServed a great quantity of Saltpetre near Lima, upon earths which ferve for pafture, and which produce only graminerous plants. Mr. Talbot Dillon, in his travels in- to Spain, relates that one third of all the grounds, and in the Southern parts of that kingdom, even the diift of the roads, con- tain falt-petre Salt-petre is extraaed in France from the ruins and plafter of old ho ufes. This fait exifts ready formed in vegetables, fiich as parietaria and buglofs, §cc. and one of my pupils, Mr. Virenque, has proved that if is produced in all extraas which are capable of fermenting. The fermentation of faltpetre may be favoured, by caufing certain circumftances to concur which are of advantage to its formation. In the North of Europe, the Salt-petre beds are formed with lime, afhes, earth of uncultivated grounds, and ftraw, which are Stratified, and watered with urine, dunghill-water, and mother waters. TheSe beds are defended by a covering of heath or broom. In the year 1775, tne K'ng caufed a prize to be pro- pofed by the Royal Academy,of Sciences at Paris, to difcover a method of increafing the produa of faltpetre in France, and to relieve the people from the obligation of permitting the falt- petre makers to examine their cellars, in order to difcover and carry away faltpetre earths. Several Memoirs were offered on the fubject, which the Academy united into a fingle volume i and thefe have added to our knowledge, by inftruaing us more efpecially concerning the nature of the matters which favour the formation of nitre, ft was known, for example, long fince, that rntre is formed in preference near habitations, or in earths-,- iftH Production of Nitre. { - pregnared with animal produas : it was likewife known that, in general, the alkaline bafis was afforded by the concurrence of a vegetable fermentation. Mr. Thouvenel, whofe memoir was crowned, has proved that the gas which is difengaged by putre- faaion, is neceffary for the formation of nitre ; that blood, and next to it, urine, ■".ere the animal parts which were the moft fa- vourable to its formation ; that the moft minutely divided and the lightcft earths were the moft proper for nitrification ; that the current of air muft be properly managed, to fix upon thefe earths the nitrick acid which is formed, &c v It feems to me that Becher poffeffed a confiderably accurate knowledge of the formation of nitre, as appears from the follow- ing paffages : " Haec enim (vermes, mufcse, ferpentes) putrefaaa in terram " abeunt prorfus nitrofam ; ex qua etiam communi modo nitrum " copiofum parari poteft, fola elixatione cum aqua communi."—. Phyf. Subt. lib. i. S. V. t. i. p. 286. " Sed et ipfum nitrum necdum finis ultimus putrefaaionis "eft; nam cum ejuSdem partes igneae Separantur, relinquae in " terram abeunt prorfum puram & infipidam, Sed Singular! •* magnetiSmo prseditam novum Spiritum aerum attrahendi, ,f rurfufque nitrum fiendi."—PhyS. Subt. S. V. t. i. p. 292. From all the diScoveries and observations which have beeri hitherto made, it Sollows that, in order to eftablifh artificial nitre beds, it is neceffary that animal putrefaaion and vegetable fer- mentation Should concur. The nitrogene gas, ii»its disengage- ment from the animal fubftances, combines with the oxigene, and forms the acid, which again unites with the alkali, whofe formation is favoured by the vegetable decompofition. When the manufeaurer is in poffeffion oS Saltpetre grounds, whether by the fimple operations oS nature or by the affiftanc* OS art, the Saltpetre is extraaed by the lixiviation oS theSe earths; which lixivium is aSterwards concentrated, and made to cryftal- lize. In proportion as the evaporation goes forward, the marine fait, which almoft always accompanies the formation of nitre, is precipitated. This is taken out with ladles, and fet to drain in bafkets placed over the boilers. As a great part of the nitre has an earthy bafis, and requires to be furnifhed with an alkaline bafis to cauSe it to cryftallize, this purpoSe is accomplifhed either by mixing afhes with the Saltpetre earths, or by adding an alkali ready formed to the lix- ivium itfelf. Nitre obtained by this firft operation is never pure, but con- tains fea-falt, and an extraaive and colouring principle, from which it muft be cleared. For this purpofe it is diffolved in U *£4 Compofition of Gunpowder. frefh water, which is evaporated, and to which bullock's blocxi may be added, to clarify the folution. The nitre obtained by the fecond manipulation is known by the name of Nitre of the Second Boiling. If recourfe be had to a third operation to purify it, it is then called Nitre of the Third Boiling. The purified nitrate of pot-afh is employed in delicate opera- tions, fuch as the manufaaure of gunpowder, the preparation of aqua fortis for parting, and the folution of mercury, &c. The faltpetre oS the firft boiling is ufed in thoSe works where aqua fortis is made for the diers. It affords a nitro-muriatick acid, which is capable of diffolving tin by itfelf. The nitrate of pot-afh cryftallizes in prifmatick oaahedrons> which almoft always reprefent fix-fided flattened priSms, termi- nated by dihedral Summits! It has a penetrating tafte followed by a SenSation of coldnefs. It is fufible upon ignited coals; and in this cafe its acid is de- compofed. The oxigene unites with the carbone and forms the carbonick acid ; the nitrogene gas and the water are diffipated ; and it is this mixture of principles which has been known by the name of Clyffus of Nitre. The diftillation of the nitrate of pot-afh affords twelve thou- fand cubick inches of oxigenous gas for each pound of the fait. Seven parts of water diffolve one of nitre, at fixty degrees of Fahrenheit j and boiling water diflblves its own weight of this fait. One hundred grains of the cryftals of nitre contain thirty acid, Sixty-three alkali, and Seven water. When a mixture of equal parts of nitre and fulphur are thrown into a red-hot crucible, a faline fubftance is obtained,, which was formerly called Sal Polychreft of Glafer, and which has fince been confidered as Sulphate oS Pot-afh. If nitre be fufed, and a few pinches of fulphur be thrown upon this fait in Sufion, and the whole be afterwards poured out or call into plates, it forms a fait known by the name of Cryftal Mineral. A mixture of feventy-five parts of nitre, nine and a half of fulphur, and fifteen and a half of charcoal, forms gunpowder. . • This mixture is triturated from ten to fifteen hours, care being taken to moilten it from time to time. This trituration is ufual- ly performed by pounding mills, whofe peftles and mortars are of wood. In order to give the powder the form proper to gran- ulate it, it is paffed through fieves of fkin, whofe perforations are of various fizes. The grained powder is then Sifted, to feparate the duft, and it is afterwards carried to the drying-houfe. Gun- powder for artillery, or cannon-powder, receives no other pre- paration j but it is neceffary to glaze the powder which is in- Fulminating Powder. lS5 tended for fowling. This laft preparation is effeaed by putting at into a kind of cafk which turns on an axis, and by whofe movement the angles of the grains are broken, and their fur- faces polifhed. We are indebted to Mr. Baume and the cheva- lier Darcy for a feries of experiments, in which they hav« proved— i. That good gunpowder cannot be made without fulphur. 2. That charcoal is likewife indifpenSably neceffary. 3. That the quality of gunpowder depends, ceteris paribus, upon the accuracy with which the mixture is made. 4. That the effea of gunpowder is greater when limply dried than when it is granulated. The effea of gunpowder depends upon the rapid decompofi- tion which is made in an inftant of a confiderable mafs of nitre, and the fudden formation of thofe gafes which are the immedi- ate produa. Bernoulli, in the laft century, afcertained the developement of air by the deflagration of gunpowder: he plac- ed four grains of powder in a recurved tube of glafs, plunged the tube in water, and fet fire to the gunpowder by means of the burning-glafs ; after the combuftion the interiour air occu- pied a larger fpace, fo that the fpace abandoned by the water was fuch as would have contained two hundred grains of gun- powder.—Hift. de l'Acade'mie des Sciences de Paris, 1696, t. ii. Memoire de M. Varignon furte Feu et la Flamme. The fulminating powder, which is made by the mixture and trituration of three parts of nitre, two of fait of tartar, and one of fulphur, produces effeas ftill more terrible. In order to ob- tain the full effea, it is expofed in a ladle to a gentle heat; the mixture melts, a fulphureous blue flame appears, and the explo* fion takes place. Care muft be taken to give neither too ftrong nor too flight a degree of heat. In either cafe, the combuftion of the principles takes place feparately, and without explofion, ARTICLE II. Nitrate of Soda. This fait has received the name of Cubick Nitre on account of its form ; but this denomination is not exaa, becaufe it af- feas a figure conftantly rhomboidal. It has a cool, bitter tafte. It flightly attraas the humidity of the air. Cold water, at Sixty degrees of Fahrenheit's thermometer, dif- folves one third of its weight 5 and hot water Scarcely diffulveu anore. i$6 Muriatick Acid. It fufes upon burning coals with a yellow colour ; whereas common nitre affords a white flame, according to Margraff— 24 Differt. fur le Sel Commun, t. ii. p. 343. 100 grains of this fait contain 28.80 acid, 50.09 alkali, and 21.11 water. It is almoft always the produa of art. ARTICLE III. Nitrate of Ammoniack. The vapours of ammoniack, or volatile alkali, being brought into contaa with thoSe of the nitrous acid, combine with them, and form a white and thick cloud, which flowly fubfides. But when the acid is direaiy united to the alkali, the reSuIt is a Salt, which has a cool, bitter, and urinous tafte. Mr. De Lille pretends that it cryftallizes in beautiSul needles, fimilar to thoSe of Sulphate of pot-afh. TheSe cryftals cannot be obtained but by a very flow evapo- ration. When this fait is expofed to the fire, it liquefies, emits aque- ous vapours, dries,' and detonates. Mr. Berthollet has analyfed all the reSults of this operation, and has drawn from them a new proof of the truth of the prin- ciples which he has eftablifhed with regard to ammoniack. CHAPTER IV. Concerning the Muriatick Acid. THIS acid is generally known by the name of Marine Acid, and it is ftill diftinguiflied among artifans by the name of Spirit: of Salt. It is lighter than the two preceding acids j it has a Strong penetrating fmell, refembling that oS Saffron, but infinitely more pungent; it emits white vapours when it is concentrated ; it precipitates filver from its folution in the form oS an inSoluble fait, &c. This acid has no where been found difengaged ; and to obtain it in this ftate, it is neceffary to difengage it Srom its combinations. Common fait is uSually employed for this purpofe. Diflillation of Muriatick Acid. 15? The fpirit oS Salt oS commerce is obtained by a proceSs little differing Srom that which is uSed in the extraaion of aqua for-. tis. But as this acid adheres more ftrongly to its bafis, the pro- dua is very weak, and only part oS the marine falt-is decom- posed. Flints pulverized and mixed with this Salt, do not Separate the acid. Ten pounds of flints in .powder, treated by a violent fire with two pounds oS the Salt, did not afford me any other produa than a mafs of the colour of litharge. The fumes were not perceptibly acid. If clay, which has once ferved to decompofe marine fait, be mixed with a new quantity of the fame fait, it will not decompofe an atom of it, even though the mixture be moiftened and formed into a pafte. Thefe experi- ments have been feveral times repeated in my manufaaory, and? have conftantly exhibited the fame refults. The fulphate of iron, or martial vitriol, which fo eafily difen- engages the nitrick acid, decompoSes marine Salt •, but very im- perSeaiy. The impure Soda known in France by the name of Blan- quette,and in which my analyfis has exhibited twenty-one pounds of common Salt out oS twenty-five, Scarcely affords any muria- tick acid when it is diftilled with the Sulphurick acid ; but it af- fords abundance oS Sulphureous acid. Mr. Berard direaor of rfly manuSaaory attributed theSe reSults to the coal contained in this Soda, which decompoSed the Sulphurick acid. He there- fore calcined the blanquette to deftroy the charcoal : and ihen he Sound he could treat it in the Same manner as common Salt, and with the Same SucceSs. The Sulphurick acid is uSually employed to decompoSe ma- rine Salt. My method oS proceeding confifts in drying the ma- rine Salt, pounding it, and putting it into a tubulated retort placed upon a Sand bath. A receiver is adapted to the retort, and af- terwards two bottles, aSter the manner of Woulfe, in which I distribute a weight of diftilled water equal to that of the marine fait made ufe of. The joinings of the veffels are then luted, but with the greateft caution ; and when the apparatus is thus fitted up, a quantity of fulphurick acid is poured through the tubulure equal to half the weight of the fait. A confiderable ebullition is immediately excited : and when this effervefcence is flackened, the retort is gradually heated and the mixture made to boil. The acid is difengaged in the ftate of gas ; and mixes rap- idly with the water, in which it produces a confiderable degree 15^ Oxigenated Muriatick Acith The water of the firft bottle is uSually Saturated with th# acid gas, and Sorms a very concentrated and fuming acid ; antf though the Second is weaker, it may be carrried to any defined degree of concentration, by impregnating it with a new quan- tity of the gas. The ancient chemifts were divided refpeaing the nature of the muriatick acid. Becher fuppofed it to be the fulphurick acid modified by his mercurial earth. This acid is fufceptible of combining with an additional dofe of oxigene ; and, what is very extraordinary, it becomes^nore volatile in confequence of this additional quantity ; whereas the other acids appear to acquire a greater degree of fixity in the fame circumftances. It may even be faid, that its acid virtues become weaker in this cafe, fince its affinities with alkalis di? miniffi ; and it is fo far from reddening blue vegetable colours, that it deftroys them. Another phenomenon not lefs interefting, which is prefented to us by this new combination, is, that though the muriatick acid feizes the oxigene with avidity, yet it contrafts fo weak a, union with it, that it yields it to almoft all bodies, and the mere aaion of light alone is fufficient to difengage it. it is to Scheele that we are indebted for the difcovery of the oxigenated muriatick acid. He formed it in the year 1774, by employing the muriatick acid as a folvent for manganefe. He perceived that a gas was difengaged, which poffeffed the diftinc- tive fmell of aqua regia ; and he was of opinion that in this cafe the muriatick acid abandoned its phlogifton to the man- ganefe ; in confequence of which notion he called it the De- phlogifticated Marine Acid. He took notice of the principal and truly aftonifhing properties of this new fubftance ; and aM chemifts fince his time have thought their attention well emr ployed in examining a Subftance which exhibits Such Singular properties. To attraa this acid, I place a large glaSs alembick of one fin-; gle piece upon a fand bath. To the alembick I adapt- a fmall receiver ; and to the receiver three or four fmall bottles nearly filled with diftilled water, and arranged according to the method, "j of Woulfe. I difpoSe the receiver and the bottles in a ciftern, the places of junaion being luted with fat lute, and fe- eured with rags foaked in the lute of lime and white of egg. Laftly, I furround the bottles with pounded ice. When the apparatus is thus difpofed, I introduce into the alembick half a pound of manganefe of Cavennes, and pour upon it, at feveral repetitions, three pounds of fuming muri- atick acid. The quantity of acid which I pour at once i* thrcs Oxigenated Muriatick Arid. *S9 ounces; and at each time of pouring a confiderable efferves- cence is excited. I do not pour a new quantity until nothing more comes over into the receivers. This method of proceed- ing is indifpenfably neceffary, when the operator is defirous of making his proceSs with a definite quantity of the materials. For if too large a quantity of acid be poured at once, it is im- poffible to reftrain the vapours; and the efferveScence will throw a portion of the manganefe into the receiver. The vapours which are developed by the affufion of muriatick acid are of * greenifh yellow colour ; and they communicate this colour to the water when they combine with it. When this vapour is concentrated by means of the ice, and the water is faturaterl with it, it forms a fcum at the furface, which is precipitated through the liquid, and refembles a congealed oil. It is neceffa- ry to affift the aaion of the muriatick acid by means of a mod- erate heat applied to the fand bath. The fecure luting of the? veffels is alfo an effential circumftance ; for the vapour which might efcape is fuffocating, and would not permit the chemift to infpea his operation clofely. It is eafy to difcover the place where it efcapes through the lutes, by running a feather dipped in volatile alkali over them , the combination of thefe vapours inftantly forms a white cloud, which renders the place vifible where the vapour efcapes. An excellent Memoir of Berthollet, publifhed in the Annales Chenaiques, may be confulted upon the oxigenated muriatick acid. The fame oxigenated muriatick acid may be obtained by dif- tilling, in a fimilar apparatus, ten pounds of marine fait, three or four pounds of manganefe, and ten pounds of fulphurick acid. Mr. Reboul has obferved that the concrete ftate of this acid is a cryftallization of the acid, which takes place at three de- grees of temperature below the freezing point of Reaumur. The forms which have been obferved are thofe of a quadrangular prifm truncated very obliquely, and terminated by a lozenge. He has likewiSe obferved hollow hexahedral pyramids on th« Surface br" the liquor. To make uSe of the oxigenated acid in the arts, and in order to concentrate a greater quantity in a given volume of water, the vapour is made to pafs through a folution of alkali. A white precipitate is at firft formed in the liquor ; but a fhort time af- terwards the depofition diminishes, and bubbles are difengaged, v. inch are nothing but the carbonick acid. In this cafe two falts are formed, the oxigenated muriate and the ordinary muri- ate. The mere impreflbn of light is fufficient to decompofe ihc farmer, and convert it into common fait. This lixivium iCo Oxigenated Muriatick Acid. contains, indeed, the oxigenated acid in a Stronger proportion. The execrable Smell oS the acid is much weakened. It may be employed Sor various uSes, with the Same fuccefs, and with great facility ; but the effea is very Sar Srom corresponding with the quantity oS oxigenated acid which enters into this combination,' becaufe the virtue of a great part is deftroyed by its union with the alkaline bafis. The oxigenated muriatick acid has an exceffively Strong Smell. It aas directly on the larynx, which it ftimulates, excites cough- ing, and produces violent head-achs. Its tafte is Sharp and bitter. It Speedily deftroys the colour *>f tinaure oS turnSole. But it appears that the property which moft oxigenated Subftances poffeSs, of reddening blue colours, arifes only from the combination of oxigene with the colouring principles ; and that, when this combination is very Strong and: rapid, the colour is deftroyed. The oxigenated muriatick acid with which a Solution of cauf- rick alkali is Saturated, affords, by evaporation in veflels feclud- ed from the light, Common muriate and oxigenated muriate. This laft detonates upon charcoal; is more foluble in hot than :n cold water; cryftallizes, fometimes in hexahedral laminae, and oftener in rhomboidal platen Thefe cryftals have an ar- gentine brilliancy, like mica. Its tafte is faint ; and its crvftals, when they are diffolved in the mouth, produce a fenfation of coolnefs refembling that of nitre. Mr. Berthollet has afcertained, by delicate experiments that the oxigenated muriatick acid which exifts in the oxigenated muriate of pot-affi, contains more oxigene than an equal weight of oxigenated muriatick acid diffolved in water; and this has' led him to confider the oxigenated acid combined in the muriate as being fuperoxigenated. He confiders the common muriatick gas with relation to the oxigenated muriatick gas, the fame as the nitrous gas or Sulphureous ga3 with refpect to the nitrick and fulphurick acide. He pretends that the produaion of the fimple muriate and the oxigenated muriate in the fame opera- tion", may be compared to the aaion of the nitrick acicf, which iri many cafes produces nitrate and nitrous gas. Hence he has confidered the muriatick acid as a pure radical, which, combin- ed with a greater cr lefs quantity of oxigeiie, forms either fim- ple muriatick aeid gas, or the oxigenated muriatick acid gas. The oxigenated muriates of foda do not differ from thofe of pot-affi, but in being more deliquefcent and foluble in alcohol, like all the falts of this nature. The oxigenated muriate of pot-afh gives out its Oxigene in the light, and by diftillation as foon as the veffel is heated W / Gunpowder with Muriatick Salt. I6l rednefs. One hundred grains of this fait afford feventy-five cubick inclies of oxigenous gas reduced to the temperature of twelve degrees of Reaumur. This air is purer than the others, and may be employed for delicate experiments of the oxigenat- ed muriate of pot-afh, when cryftallized, does not trouble the Solutions of nitrate of lead, of filver, or of mercury. Mr. Berthollet has fabricated gunpowder, by fubftituting the oxigenated muriate inftead of faltpetre. The effeas it produced were quadruple. The experiment in the large way, which was made at Effone, is but too well known by the death of Mr. Le Tors and Mademoifelle Chevraud. This powder exploded the moment the mixture was triturated. The oxigenated muriatick acid whitens thread and cotton. For this purpofe the cotton is boiled in a weak alkaline lixivi- um ; after which the fluff is wrung out, and fleeped in the oxi- genated acid. Care is taken to move the cloth occafionally in the fluid, and to wring it out. It is then wafhed in a large quantity oS water, to deprive it of the fmell with which it is impregnated. I have applied this known property to the whitening of paper and old prints: by this means they obtained a whireneSs which they never before poffeffed. Common ink disappears by the aaion of this acid ; but printers' ink is not attacked by it, Linen and cotton cloths, and paper, may be bleached by the vapour of the oxigenated marine acid. I have made fome ex- periments in the large way, which have convinced me of the poffibility of applying this method, to the arts. The memoir in which I have given an account of my experiments, will be print- ed in the volume of the Academy of Paris for the year 1787. The oxigenated muriatick acid thickens oils; and oxides met- als to fuch a degree, that this procefs may be advantageoufly ufed to form verdirer. The oxigenated muriatick acid diffolves metals without ef- ferveScence ; becaufe its oxigene is fufficient to oxide them without the neceflity of the decompofition of water, and confe- quentlyof the difengagement of gas. This acid precipitates mercury from its Solutions, and con- verts it into the ftate oS corrofive Sublimate. It converts Sulphur into Sulphurick acid, and inftantly deprives the very black Sulphurick acid of its colour. When mixed with nitrous gas, it paffes to the ftate of muriat- ick acid, and converts part of the gas into nitrick acid. When expofed to light, it affords oxigenous gas, and the muriatick acid is regenerated. W r*6"2 Muriate of Pot-dflr. The muriatick acid aas very efficacioufly upon metallitk &X.+ ides merely in confequence of its becoming oxigenated ; andS in this cafe it forms with them falls, which are more or le& oxigenated. ARTICLE L Muriate of Pot-afh. This fait is Still diftinguiflied by the name of Febrifuge fait of Sylvius. It has a difagreeable ftrong bitter tafte. It cryftallizes in cubes, or in tetrahedral prifms. It depcripitates upon coals v and when urged by a violent heat it fufes, and is volatilized without decompofition. It requires three times its weight of water, at the temperature of Sixty degrees of Fahrenheit, for its folution. ft is fubjea to fcarcely any alteration in the air. One hundred grains of this fait contain 29.68 acid, 6*3.4? alkali, and 6.85 water. It is frequently met with, but in fmall quantities, in the water of the fea, in plafter, in the afhes o£ of tobacco, &c. The exiftence of this fait in the afhes of to- bacco might with juftice have furprized me, as I had reafon to expea the muriate of foda* which is employed in the operation called watering. Was the foda metamorphofed into pot-afh by the vegetable fermentation1 i This may be determined by di- tea experiments. ARTICLE IT. Muriate of Soda. The received names of Marine Salt, Common Salt, and Cu-* linary Salt, denote the combination of muriatick acid with foda. This Salt has a penetrating but not bitter tafte. It depre- ciates on coals, fufes, and is volatilized by the heat of a glafs. maker's Surnace, without decompofition. It is Soluble in 2.5 times its weight oS water, at Sixty degrees of Fahrenheit's thermometer. One hundred grains of this fait contain 33.3 acid, 50 of alka- li, and 16.7 of water. It cryftallizes in cubes. Mr. Gmelin has informed us that the Salt oS the Salt lakes in the environs of Sellian on the banks of the CaSpian Sea, Sorms cubical and rhomboidal crystals* Muriate of Soda or Common Salt. 163 "Mr. De Lifle obferves, that a folution of marine fait, left to Snfenfible evaporation during five years by Mr. Rouelle, had formed regular oaahedral cryftals reSembling thoSe oS alum. Marine Salt may be obtained in oaahedr-ons, by pouring Srefh urine into a very pure Solution oS frefh fait. Mr. Berniard is convinced that this addition changed only the form of-the fait, without altering its nature. Common fait is found native in many places. Catalonia, Cal- abria, Switzerland, Hungary, and Tyrol, poffeSs mines which are tnore or lefs abundant. The richeft fait mines are thofe of Wie- liczka in Poland. Mr. Berniard has given us a defcription of them in the Journal de Phyfique ; and Mr. Macquart, in his Efl'ays on Mineralogy, has added interefting details concerning the working of theSe mines. Our Salt Springs in Lorraine and Franche-compte, and Some indications afforded by Bleton, have appeared fufficient motives to Mr. Thouvenel to prefume that Salt mines exift in our king- dom. This chemift expreffes himfelf in the following man- ner : ♦« At the diftance of two leagues from Saverne, between the village of Huaenhaufen and that of Garbourg, in a lofty moun- tain called Penfenperch, there are two great refervoirs of fait water ; the one to the eaft, at the head of a large deep and ©arrow valley, which is called the great Limerthaal ; the other to the weft, upon the oppofite flope, towards Garbourg. They communicate together by five fmall flreams, which are detach- ed from the upper refervoir, and unite in the lower one. From theSe two fait refervoirs flow two large Streams ; the upper runs into Franche-compte, and the lower into Lorraine, where they fupply the well known fait works." The waters therefore flow to the diftance of Seventy leagues from the refervoir. Salt mines appear to owe their origin to the drying up of vaft lakes. The Shells and madrepores found in the immenfe mines of Poland are proofs of marine depofitions. There are likewife Some feas in which the fait is fo abundant, that it is depofited at the bottom of the water ; as appears from the analyfis of the water of the lake Afphaltites, made by Mefirs. Maquer and Sage. This native fait is often coloured; and as in this ftate it poffeffes confiderable brilliancy, it is called Sal-gem. It al- moft always contains an oxide oS iron, which colours it. As theSe Salt mines are neither Sufficiently abundant to Sup- ply the wants oS the inhabitants of the globe, nor diftributed with that uniformity as to permit all nations to have ready re- 164 Extraction of Salt from Water. courfe to them, it has been found neceffary to extraa the fait from the water of the fea. The kd does not contain an equal quantity in all climates : IngenhouSz has Shewn us that the northern Seas contain leSs than the Southern. Marine Salt is So abundant in Egypt, that, according to Haffelquift, a frefh-water fpring is a treafure which is Secretly tranSmitted Srom father to fon. The method of extraaing the water of the fea varies accor- . ding to the climates. i. In the northern provinces, the fait fands of the fea coaft are wafhed with the leaft poffible quantity of water, and the fait is obtained by evaporation.-—See the defcription of this pro-i cefs by Mr. Guettard. 2. In very cold countries, fait water is concentrated by freez- ing, and the refidue is evaporated by fire.—See Wallerius. 3. At the Salt Springs oS Lorraine and Franche-compte, the water is pumped up, and Suffered to fall upon heaps of thorns which divide it, and caufe a part to evaporate. The farther concentration is effeaed in boilers. 4. In thejjjuthern provinces, at Peccais, at Peyrat, at Cette and elfewhere, the extraaion is begun by feparating a certain quantity of water from the general mafs of the fea, which is fuf- fered to remain in Square fpaces, called Partenemens. For this purpofe it is neceffary to have fluices which may be open- ed and Shut at pleaSure, and to form Surrounding walls which prevent all communication with the Sea, except by means of theSe gates. It is in the partenemens that the water goes through the firft ftate oS evaporation.; and when it begins to depofite its Salt, it is raiSed by bucket wheels to other Square compartments, called Tables, were the evaporation finifhes. The Salt is heaped together, to form the cammelles; in which State it is left for three years, in order that the deli- queScent Salts may flow out oS it; and, aSter this interval of time, it is carried to market. Exertions and enquiries have long fince been made to difcov- er a cheap method of decompofing marine fait, to obtain the mineral alkali at a low price, which is of fuch extenfive ufe in the manuSaaories oS Soap, glaSs, bleaching, &c The proceffes, hitherto discovered are the Sollowing ; 1. The nitrick acid diSengages the muriatick acid, and Sorms nitate oS Soda, which may be eafily decompoSedby detonation, 2. Pot-afh displaces the Soda, even in the cold, as I Sound by experiment. 3. The Sulphurick acid Sorms Sulphate oS Soda by decompo-i Sing the marine Salt \ the new Salt, when heated with charcoal, Muriate ef Ammoniack. 16*5 is deftroyed ; but the Sulphure of Soda, or liver oS Sulphur, is formed, which is difficult to be entirely Separated ; and this proceSs does not appear to me to be economical. The Sulphure may likewiSe be decompofed by the acetite oS barytes, and the Soda afterwards obtained by calcination of the acetite of foda. 4. Margraff tried in vain to acomplifh this purpofe, by means of lime, ferpenline, iron, clay, &c. He adds that if common fait be thrown upon lead heated to rednefs, the fait is decom- pofed, and muriate of lead is formed. 5. Scheele has has pointed out the oxides of lead for the decompofition of common fait. If common fait be mixed with litharge, and made into a pafte, the litharge gradually lofes its colour, and becomes converted into a white matter from which the foda may be extraaed by wafhing. It is by proceffes of this kind that Turner extraas it in England ; but this decom- pofition never appeared to me to be complete unlefs the litharge was employed in a proportion quadruple to that of the fait. I have obferved that almoft all bodies are capable of alkalizing marine fait, but that the abfolute decompofition is very difficult 6. Barytes decompofes it likewiSe, according to the experi- ments oS Bergmann. 7. The vegetable acids, combined with lead, may likewiSe be uSed to decompoSe common Salt. When theSe Salts are mixed, a decompofition takes place : the muriate oS lead Sails down ; and the vegetable acid, united to the Soda, remains in Solution. The vegetable acid may be diffipated by evaporation and calcin- ation : and the alkali remains diSengaged. Marine Salt is more eSpecially employed at our tables, and in culinary purpoSes. It removes and correas the infipidity oS our Sood, and at the Same time Sacilitates digeftion. It is ufed in a large proportion to preServe flefh Srom putreSaaion ; but in a Small dofe it haftens that proceSs, according to the experiments oS Pringle, Macbride, Gardane, &c, ARTICLE III. Muriate of Ammoniack. Of all the combinations of ammoniack this is the moft inter- efting, and the moft generally ufed. It is known by the name of Sal Ammoniack. This fait may be direaiy formed by decompofing the muriate of lime by the means of ammoniack, as Mr. Baume has prac- tifed at Paris. But almoft all the fal ammoniack which circu- lates in commerce ii brought to us from Egypt, where it is ex- $66 Mxtratlion of Sal AmmcniacL traaed by diftillation from foot, by the combuftion of the ex* crements of fuch animals as feed on faline plants. The details of the procefs which is ufed have not been very long known. One of the firft writers who gave a deScription of this operation is Sather Sicard. He inSormed us, in 1716, that diftilling veffels were charged with the foot of the excrements of .oxen, to which Sea fait and camels' urine were added. Mr. Lemaire, conful at Cairo, in a letter written to the acad- emy of Sciences in 1720, affirma that neither urine nor fea fait are added. Mr. Haffelquift has communicated to the Academy of Stock- holm a cenfiderably extenfive deScription of the procefs : by which we learn that the dung of all animals which feed on fa- line plants is indiscriminately uSed, and that the foot is diftilled, to obtain Sal ammoniack. This dung is dried by applying it againft the walls : and it is burned inftead of wood, in Such countries as do not poffeSs that fuel. The fublimation is perSormed in large round bottles of one foot and a half diameter, terminating in a neck of two inches in height; and they are filled to within four inches of the neck. The fire is kept up during three times twenty-fouc hours ; the fait is fublimed to the upper part of thefe veffelsj, where it forms a mafs of the fame figure as the veffels them- felves. Twenty pounds of foot afford fix pounds of fal ammon- iack, according to Rudenfkield. I was always of opinion that fal ammoniack might be extraa- ed by treating the dung of the numerous animals which feed on faline plants in the plains Of La Camargue and La Crau, in the fame manner ; and after having procured, with the greateft dif- ficulty, two pounds of the foot, I extraaed from it four ounces, of fal ammoniack. I muft obServe, to Save much trouble to thoSe who may wifh to follow this branch of commerce, that the dung produced during the fummer, the fpring, or the au- tumn, does not afford this Salt. I did not know to what circum- ftance to attribute the versatility of my reSults, until I found that thefe animals do not eat faline vegetables, excepting at the time when frefh plants cannot be had ; and that they are reduc^ ed to the neceflity of having recourfe to faline plants only dur- ing the three winter months. This obfervation appears do me to be a proof, that marine fait is decompofed in the firft paffij- ges ; and that the Soda is modified to the ftate oS ammoniack. Sal ammoniack is continually Sublimed through the aperture^ of volcanick mountains. Mr. Ferber Sound it ; and Mr. Sage admitted its exiftence among volcanick produas. It is found in the grottos of Puzzolo, according to Meffrs. Swab, Schefr fer, &c. Nitro-Muriatick Acid". f (fa It is found ill the country of the Calmuks. Model ani* lyfed it. It is alfo produced in the human body, and exhales by perfpa^ ration in malignant fevers. Mr. Model has proved this faa in bis own perfon: for at the time of a violent Sweat which termi- nated a malignant fever, he waffied his hands in a Solution of pot-afh, and obServed that a prodigious quantity of alkaline gas was difengaged. Sal ammoniack cryftallizes by evaporation in quadrangular pyramids. It is often obtained in rhombick cryftals by fublima-' tion. The concave face of the loaves of fal ammoniack in commerce is fometimes covered with thefe cryftals. ThUs Salt has a penetrating, acrid, urinous tafte. It poffeffes a degree of duaility which renders it flexible, and cauSes it to yield to a blow of the hammer. It does not change in the air ; which circumftance renders it probable that our Sal ammoniack is different from that mentioned by Pliny and Agricola, as that attraaed humidity. Three parts and a half of water diffolve one part of fal ammoniack, at fixty degrees of Fahrenheit's ther- mometer : a confiderable degree of cold is produced by its fo- lution. One hundred parts of fal ammoniack contain fifty-two parts acid, forty ammoniack, and eight water. This fait is not at all decompofed by clay; noT by magnefia except with difficulty, and in part only ; but it is completely de- oompofed by lime and fixed alkalis. The fulphurick and ni- trick acids difengage its acid. This fait is ufed in dying, to bring out certain colours. It is mixed with aqua fortis, to increafe its folvent power. It is ufed in foldering; in which operation it poflefles the double advantage of clearing the metallick furface, and prevent- ing its oxidation. CHAPTER V. Concerning the Nitro-muriatick Acid. THE acid which we call Nitro-muriatick, is a combination •f the nitrick and muriatick acids. Our predeceffors diftinguiflied it by the name of Aqua Regia, •n account of its property of diffolving gold. There are feveral known proceffes for making this mixed »?kh t6B Nitro-Muriatick Acid. If two ounces of common fait be diftilled with four of nitrick acid, the acid which comes over into the receiver will be good nitro-muriatick acid. This is the proceSs oS Mr. Baume. The nitrate of pot-afh may be decompofed by diftilling two parts of muriatick acid from one of this Salt: good aqua regia is the produa of this operation ; and the refidue is a muriate of pot-afh, according to Mr. Cornette. Boerhaave affirms that he obtained a good aqua regia, by dif- tilling a mixture of two parts of nitre, three of fulphate of iroa or martial vitriol, and five of common fait. The fimple diftillation of nitre of the firft boiling affords aqua regia ; which is employed by the diers in the folutiin of tin, Sor the compofition of the Scarlet die. This aqua fortis is a true aqua regia: and it is by virtue of the mixture of acids that it diffolves tin ; for if it confifted of the nitrick acid in a ftate of too great purity, it would corrode and oxide the metal without diffolving it. The diers then fay that the aqua fortis precipitates the tin ; and they correa the acid by difloving fal ammoniack or common fait in it. Four ounces of fal ammoniack in powder, diffolved gradually, and in the cold, in one pound of nitrick, form an excellent aqua regia. An oxigenated muriatick acid gas is difengaged for a long time ; which it is imprudent to attempt to coerce, and which ought to be fuffered to efcape by convenient apertures. Aqua regia is likewife formed by mixing together two parts• of pure nitrick acid and one of muriatick acid. The very evident fmell of oxigenated muriatick acid, which is diSengaged in every proceSs which can be adopted to form fhe acid at prefent in queftion ; and the property which it poffeffes equally with the oxigenated muriatick acid, of diffolving gold, have led certain chemifts to infer that, in the mixture of thefe 'two acids, the muriatick acid feized the oxigene of the nitrick, and affumed the character of oxigenated muriatick acid; fo that the nitrick acid was confidered as anfwering no other pur- pofe than that of oxigenating the muriatick. But this fyftem is inconfiftent; and though the virtues of the muriatick acid are modified by this mixture, and it is oxided by the decompofition of a portion of the nitrick acid, neverthelefs the two acids ftill exift in the aqua regia : and I am convinced that the belt made aqua regia, faturated with pot-afh, will afford the ordinary muri-* ate, the oxigenated muriate, and the nitrate. It appears to me that the powerful aaion of aqua regia, depends fimply on the union of the two acids ; one of which is exceedingly well cal- culated to oxide the metals, and the other diffolves the oxided or calces with the greateft avidity. Acid of Borax. 16*9 CHAPTER VL Concerning the Acid of Borax. THE acid of bora*, more generally known by the name of 6f Homberg's Sedative Salt, is almoft always afforded by the decompofition of the borate of foda, or borax. But it has been found perfeaiy formed in certain places and we have reaSon to hope that we Shall Speedily acquire more accurate information teSpeaing its nature. Mr. Hoefer, direaor of the Parmacies of Tufcany, was the firft who deteaed this acid fait in the waters of the lake Cher- chiajo, near Monte-rotondo, in the inferiour province of Sienna 5 thefe waters are very hot, and they afforded him three ounces of the pure acid in one hundred and twenty pounds of the water. This Same chemifl having evaporated twelve thouSarid two hun - dred and eighty grains of the water of the lake of Caftelnuovo, obtained one hundred and twenty grains. He prefumes, moreover, that it might be Sound in the water of feveral other lakes fuch as thofe of Laffo, Monte-cerbeloni, &c. Mr. Sage has depofited in the hands of the Royal Academy of Sciences fome acid of borax, brought from the mines of Tufcany by Mr. Beffon, who colfeaed it himfelf. Mr. Weftrumb found Sedative Salt in the ftone called Cubick Quartz of Luneburg. He obtained it by decompofing this ftone by the acids of fulphur, nitre, &C. The refult of his anal- yfis is the following: Sedative Salt — ^ Calcareous earth — tl. Magnefia — T\. Clay and filex — T^ rrrL. *ron — ^*oT^ This ftone according to the observations of Laffius, has the form of fmall cubical cryftals, fometimes tranfparent, in other Specimens milky, and affords Sparks with the fteel. The acid of borax is generally found combined with foda. It is Srom this combination that it is diSengaged, and obtain- ed either by Sublimation or cryftallization. When it is propoSed to obtain it by Sublimation three pounds of calcined Sulphate oS iron, and two ounces of borate of foda are diffolved in three pounds oS water. The Solution is then filtered, and evaporated to a pellicle j after which the fub- X *7° Acid of Borax. litriation is performed in a cucurbit of glafs with its head. The acid of borax attaches itfelf to the internal furface of the head; from which it may be fwept by a feather. Homberg obtained it by decompofing of borax with the ful- phurick acid. This procefs fucceeded with me wonderfully well. For this purpofe I make uSe of a glafs cucurbit with its head, which I place on a fand bath. I then pour upon the borax half its weight of fulphurick acid, and proceed to Sublimation. The Sublimated acid is of the moft beautiful whitenefs. Stahl, and Lemery the younger, obtained the fame acid by making ufe of the nitrick and muriatick acids. To extraa the acid of borax by cryftallization, the borax is diffolved in hot water, and an excefs of fulphurick acid is pour- ed in. A fait is depofited during the cooling on the fide of the veffel, in the form of thin round plates, applied one up- on the other. This fait when dry is very light, very white and of a Silvery appearance. It is the acid of borax. We are indebted to Geoffroy for this proceSs. fiaron has added two faas : the1 firft, that the vegetable acids are equally capable oS decompofing. borax ; and the fecond, that borax may be regenerated by combining the acid Of borax with foda. This acid may be purified by folution, filtration, and evapo- ration ; but it muft be obferved, that a confiderable part is vol- atilized with the water which flies off in the evaporation. The acid of borax has a falinecobl tafte. It colours the tinc- ture of turnSole, Syrup of violets, &c. red. One pound oS boiling water diflblved no more than one hundred and eighty-three grains according to Mr. De Morveau. Alcohol dfflblves it more eafily ; and the flame which this folution affords-is of a beautiful green. This acid, when ex-< pofed to the fire, is reduced to a vitriform and tranfparent Sub- Stance, inftead of rifing ; which proves, as Rouelle has obServ- ed, that it is only Sublimed by favour of the water,, with which it forms a very volatile compound. As moft of the known acids decompofe this acid, and exhibit it in the fame form, it has been thought a justifiable conclufion that it exifts ready Sormed in the borax. Mr. Baume has even affirmed that he compoSed this acid by leaving a mixture of grey clay, greafe, and cows dung expofed to the air in a cellar. But Mr. Wiegleb, after an unfucceSsful labour of three years and a half, thinks himfelf authorized to give a formal negative to the French chemift. Mr. Cadet has endeavoured to prove-----1. That the acid of bor«x always retains a portion of the acid employed in the operation. 2. That this fame acid has ftill the mineral al- Borate of Pot-afh and Soda. «7* kali for its bafis.—Mr. De Morveau has, with his ufual Sagacity, difcuffed all the proofs brought forward by Mr. Cadet; he has fhewn that none of them are conclufive, and that the acid of borax is entitled to retain its place among the chemical ele- ments. ARTICLE I. Borate of Pot-afh. The acid of borax combined with pot-afh forms this fait. It may be obtained either by the direa combination of thefe two • feparate principles, or by decompofing borax by the addition ojf pot-affi. This fait, which is yet little known, afforded Mr. Baum§ fmall cryftals. The acids difengage it by feizing its alkaline bafe. ARTICLE n. Borate of Soda. This combination forms Borax, properly fo called. It is brought to us from the Indies ; and its origin is ftill un- known.* The article borax may be confulted in Bomare's Diaionary of Natural Hiflory It does not appear that borax was known to the ancients. The chryfocolla, of which Diofcorides Speaks, was nothing but an artificial folder, compofed by the goldSmiths themSelves, with the urine of children and ruft of copper, which were beaten together in a mortar of the fame metal. The word Borax is found Sor the firft time in the works of Geber. Every thing which has been written fince that time concerning borax, is applicable to the Subftance which is at preSent known to us by that name. Borax is found in commerce in three different ftates. • The origin of Borax is very well ascertained in two Papers, in the feventy-feventh volume of the Philofophical Transactions Number xxviii and xxix. It is dug up in a cryftallized ftate from the bottom of certain fait lakes in a mountainous, barren, volcanick diftridr, about twenty-five dava journey to the eaftward of Laffa, the capital of the kingdom of Thibet. T. 172 Hiflory and Purification of Borax. The firft is brute borax, tincall, or chrySocolla. Jt comes ic us from Perfia,' and is enveloped and foiled by a greaSy covering. The pieces of brute borax have almoft all of them the form of a fix-Sided priSm, flightly flattened, and terminated by a dihedral pyramid. The Sraaure of thefe cryftals is brilliant, with a greenifh call. This kind of borax is very impure. It is pre- tended that borax is extraaed from the Lake of Necbal, in the kingdom of Grand Thibet. This la-.e is filled with water dur- ing the winter, which exhales in the Summer ; and when the waters are low, workmen enter, who detach the cryftals from the muddy bottom, and put them into bafkets. • The Weft-Indies contain borax. It is tp Mr- Antpny Carera, a phyfician eftablifhed at Potofi, that we are indebted for this difcovery. The mines of Riquintipa, and thoSe in the neigh- • bourhood oS EScapa, afford this Salt in abundance. The nativ.es ufe it in the fufion of copper ores. The fecond kind of borax known in commerce comes from China. It is purer than the preceding, and has the form of fmall plates cryftallized upon one of their furfaces, on which the rudiments of prifms may be perceived. This borax is mix- ed with a white powder, which appears to be of an argillaceous nature. Thefe feveral kinds of borax have been purified at Venice for a long time, and afterwards in Holland 5 but Meffrs. La- guiller refine it at prefent in Paris ; and this purified borax forms the third kind which is met with in commerce. In order to purify borax, nothing more is neceffary than t0 cfear it of the un£naus fubftance which foils it and impedes its folution. Crude feorax added to a folution oS mineral alkali, \s more completely dilibl.ved, and may be obtained of confiderable beau- ty by a firft cryftallization ; but it retains the alkali made ufe of : and b«rax, purified in this manner, ppfleffes a greater por- tion of alkali than in its crude ftate. The oily part of borax may be deftroyed by calcination. By this, treatment it becomes more Soluble, and may infaa be puri- fied in this way. But the method is attended^with a considera- ble lofs, and is not So advantageous as might be imagined. The moft fimple method of purifying borax, confifts in boib'ng it ftrongly, and for a long time. This Solution being filtrated,' affords by evaporation cryftals rather Soul, which may be puri- fied by a fecond operation Similar to the foregoing. I have tried all thefe proceffes in the large way ; and the latter appeared tq me to be the moft fimpfe. Properties and Habitudes of Borax. in purified borax is white, tranfparent,-^pd has a Somewhat greaSy appearance in its Sraaure. It crystallizes in hexahedral priSms, terminated by trihedral and Sometimes hexahedral pyramids. It has a flyptick tafte. It converts Syrup of violets to a green. When borax is expofed to the fire, it fwells up, the water of cryftallization is diffipated in the form of vapour ; and the fait then becomes converted into a porous, light, white, and opake mafs, commonly called Calcined Borax. If the fire be more ftrongly urged, it affumes a pafty appearance, and is at length fufed into a transparent glaSs of a greenifh yellow colour, folu- ble in water ; and whioh loSes its transparency by expoSure tp the air, in conSequence oS a white effloreScence that Sprrns upon its Surface. This fait requires eighteen times its weight of water, at the temperature of Sixty degrees oS Fahrenheit's thermometer, to diflblve it. Boiling water diffolves one Sixth of its weight. Barytes and magnefia decompoSe bprax. Lime-water precip- itates the Solution of this Salt; and if quick-lime be boiled with borax, a fait of fparing Solubility is formed, which is the borate of lime. Borax is ufed as an excellent flux in docimaftick operations. It enters into the compofition of reducing fluxes, and is of the greateft ufe in analyfes by the blow-pipe. It may be applied with advantage in glafs manufaaories ; for when the fufion turns out bad, a fmall quantity of borax re-eftablifhes it. It is more efpecially ufed in Soldering. It aflifts the fufion of the folder, cauSes it to flow, and keeps the Surface oS the metals in a SoSt or clean ftate, which facilitates the operation. It is fcarce- ly of any ufe in medicine. Sedative Salt alone is uSed by Some phyficians ; and its name fufficiently indicates its application. Borax has the inconvenience of Swelling up, and requires the greateft attention on the part of the artift who ufes it in delicate works, more efpecially when defigns are formed with gold of different colours. It has been a long dcfideratum to Subftitute Some compofition in the room pf borax, which might poffefs its advantages without its defeas. Mr. Georgi has publifhed the following procefs:—« Natron, mixed with marine fait and Glauber's fait, is to be diffolved in lime-water ; and the cryftals which feparate by the cooling of the fluid may be fet apart. The lixivium of natron is then to be evaporated ; and this fait afterwards diffolved in milk. The evaporation affords Scarcely one eighth of the natron em- ployed, and the refidue may be applied to the fame ufes as borax." P74 Borate of Ammoniack* Meffrs. Struve and Exchaquet have proved that the phofphate ,of potr-afh, fufed with a certain quantity of fulphate of lime, forms an excellent glafs for Soldering metals.—-See the Journal de Phyfique, t. xxix. p. 78, 79. ARTICLE III. Borate of Ammoniack. This fait is ftill little lenown. We are indebted to Mr. De Fourcroy for the following indications:—He diffolved the acid of borax in ammoniack, and obtained by evaporation a bed or plate of cryftals connected togethef, whofe Surface exhibited polyhedral pyramids. This fait has a penetrating and urinous tafte; it renders the fyrup of violets green ; gradually loSes its crystalline form, and becomes of a brown colour, by the contaa of air. It appears to be of confiderable folubility in water. Lime difengages the volatile alkali. 4 PART THE SECONL>. CONCERNING LITHOLOGY; OR AN ACCOUNT OF STONY SUBSTANCES. INTRODUCTION. 1 HE object of Lithology confifts in the fludy of ftones and earths. It is generally agreed to call thofe fubftances by the name of Earth or Stone, which are dry, brittle, inodorous, infipid, fcarce- ly or not at all foluble in water, and of a fpecifick gravity not exceeding 4,5. There is no one" who has ferioufly attended to the ftudy of lithology, without being at the fame time aware of the neceflity ©f eftablifhing divifions to facilitate the knowledge of ftones, and to remove the numberlefs difficulties which would otherwiSe oppoSe the acquisition of that knowledge. It is an obvious difference between living creatures and the fubjeas of the mineral kingdom, that thefe laft are continually modified by external cauSes, Such as air, water, fire, &c. while the former, being animated and governed by an internal force, poffeSs charaaers of a more definite and unchangeable nature. The Sorms of thefe depend upon their organization ; and, in general, the proceedings of nature refpeaing them are more con- flant, and better ascertained. The earthy element appears to be paflive oS itfelf; it is obe- dient only to the laws of inanimate bodies ; and we mav refer all the phenomena of Sormation or decompofition, which a ftone is fuSceptible of, to the mere law of affinities. This, no doubt, is the caufe of that variety of forms, and that mixture of principles, which fcarcely permit the naturalift to ef- tablifh his fyftem upon fixed bafes, or to found it upon conflant and invariable charaaers. If we take a view of the proceedings of all the naturalifts who hr.ve hitherto written, we may eafily reduce them to three chiSTc*. 176 Of the ClaffificathK 1. The firft clafs, carried by the imagination alone to that epocha when this globe iffued Srom the hands of the Creator, have followed the aaions of the various deftruaive agents which alter or overturn its furface. In this way they have Shewn tts the various rocks Succeffivcly depofited or placed upon the primitive globe ; and, by Surveying the great phenomena which have happened upon our planet, they have acquired ideas more or leSs accurate reSpeaing the vaft works of decompofition and formation. 2. Others have bttfied themSelves in enquiring, by analyfis,' what are the earths or primitive matters out of Which all fhe ftones we are acquainted with are compoSed. This claSs of phi- lofophers have fupplied us with the moft valuable acquisitions refpeaing the nature, the uSes, and the decompositions of thefe fubftances; but the reSults oS analyfis, though neceffary in ac- quiring accurate notions of each ftone, are not of themfelves fufficient to form the bafis of a method of claffing ; becaufe thefe chafaaers are too difficult to be acquired, and at moft can be only uSed as Supplementary in the establishment of Such other methods as may be employed. 3. Almoft all the fyftems of claffrfication hitherto adopted,' are founded Upon the external charaaers of earthy fubftances. Some naturalifts have fought, in the variety oS Sorms exhibit- ed by the produaions of the mineral kingdom, Such principles of divifion as to them appeared fufficient. But not to mention that the fame form frequently obtains in very different ftones, this chaYaaer is rarely found, and we are ignorant of the cryf- tallization of moft of the known earths : the cryftallization can- not therefore be confidered but as an acceffary or Secondary cir- cumftance. Other naturalifts have eflabliffied their divisions upon certain properties eafy to be afcertained, fuch as that of effervefeing with acids, giving fire with the fleel, &c. But thefe charaaers do not appear to be fufficiently flria, nor fufficiently exclufive ; for nothing is more common than to find a mixture of the frag- ments of primitive rocks with thofe of calcareous ftones. Our province exhibits examples of this every ftep we take; and thefe mixtures hardened by time, poffefs both the forementioned charaaers. There are alfo ftones which, without changing th-'ir nature, give fire with the Steel, or effervefce with acids, accordingly as they are more or lefs divided. Such is the lapis lazuli, which effervefces when pulverized, but ftrikes fire when in the mafs; ths flare likewife effervefces when in powder, but not in the mafs. The classification, therefore, which is founded on thefe charaaers, is not rigorous, and may at the moft be mad£ ufe of in coniunaion with others. of Earths and Stones. 177 M. D'Aubenton is the naturalift who appears to me to have diftributed mineral fubftances with the greateft order oSany who has hitherto undertaken that talk; every thing which he fays on this fubjea Shews the experienced eye of the obferver ; and he has drawn Srom the external charaaers of bodies all the charaaers poffible to be had Srom that fource. But he could not avoid the deSeas which neceffarily accompany the princi- ples on which he has founded his fyftem; Deeply impreffed with a fenfe of the insufficiency of thefe methods, as well of the flight opportunities I have poffeffed of improving them, my endeavours have been exerted in colleaing together all the charaaers which are capable of affording any Ufeful indications. In this purfuit, I have joined the charac- ters of the naturalift to thofe of the chemift ; and though the method which I have adopted be very far from that degree oi perfeaion which might be defired, I neverthelefs prefent it to the pubiick with confidence. It differs but little from that fol- lowed by Meffrs. Bergmann and Kirwan j a circumftance which at leaft affords a prejudice in its favour. The peculiar advanta- ges which, in my opinion, ^t appears to poffefs, are—r. The lithologick produaions are diftributed equally, and into three claffes. 2. All the analogous produaions are brought together, and arranged as it were in a natural order. In a word, this fyftern. has fixed my own ideas in the moft precife manner; and this has more particularly induced me to propofe it to the pubiick.* The various earths beneath our feet are, in general, combina- tions ; and chemifts, by decompofing thefe fubftances, have Suc- ceeded in obtaining, in the laft analyfis, principles which may be confidered as earthy elements, until fubfequent acquifition* fhall either confirm or deftroy our ideas on this fubject. • I confider what is here publifhed refpe&ing Lithology as a fimple and ftiort fketch of the principles which I explain in my Lectures. It would be fudging mc with too much feverity, if the reader were to fuppofe that my pxcrfeiu dtfign is to exhibit a complete performance. A more intimate acquaintance with, this fubject may be obtained by the perufal of the following works : I. Eflai d'un Art de Fufion a 1'Aide de PAir Vital, par Erhmann. Me*- moiresdc M. Lavoifier fur le mime fujtt.—Memoirs de M. D'Arcet, fur l'Ac- lion d'un Feu egal, violent, et continu, fur un grand nombre de Terres, pi- erres, &c. 2. The woiks of Margraff and Pott, more efpecially the Lithogcogncfie of the Utter. 3. Les Pefanteurs Spccifiques des Corps, per M. Biiflbn. 4. Elements of Mineralogy, by Mr. Kirwan. 5. Le Manuel due Mineralogiftc dc Bcrgmann, enrichi de Notes par M. i'abbe Mongez. 6. La Mincralogie de M. Sage. * ♦■. Les Ouvrages fur la Chryftallographie dc M. Rome" deLifle, de M. l'Abp£ Mauy, &c- Y f 78 Limet or Calcareous Earth. The earthy elements moft extenfively diftributed are five in' number ; namely, Lime, Magnefia, Barytes, Alumine and Silex. We fhall not treat of the other primitive earths announced by Mr. Klaproth, in the adamantine fpar, and in the jargon of Cey- lon, becaufe they are yet too flightly known and too Scarce, to have any influence upon our preSent divifion. Nature appears to have formed all the mixtures and Combina- tions which conftitute Stones, out of the primitive earths here Spoken of. If we direa our attention to the nature of thefe mixtures and combinations, we fhall diftinguifh three habitudes, or modes, which eftablifh three grand divifions. We fhall immediately per- ceive that thefe earths are,in fome inftances, combined with acids*- Which form Saline Stones ;' that in other inftances they are mixed with each other, and form ftones properly fo called, and that in Other inftances again, theSe ftones So forrned by the mixture of primitive earths, are united together, or fixed in a gluten or cement, which forms rocks, pebbles, or compound ftones. We fhall therefore diftinguifh three claffes in Lithology : the firft will comprehend Saline ftones ;. the Second ftones, properly fo called, or earthy mixtures ; and the third rocks, or ftqny ad- mixtures. We confider it as indiSpenSably neceffary to explain the nature of the primitive earths, before we can proceed to treat of their- combinations; t. Lime. This earth has been found totally difengaged from all combi- nation, near Bath.—See Falconer on the Bath Waters, vol. i. p. 156 and 157. But as this is perhaps the only observation oS the kind which we poffefs, it is indiSpenSably neceffary to Shew the proceSs by which lime may be obtained in a ftate of the greateft purity. For this purpofe chalk is to be wafhed in boiling diftilled wa- ter, then diffolved in diftilled acetous acid, and precipitated by the carbonate of ammoniack, or mild volatile alkali. The pre- cipitate, being wafhed and calcined, is pure lime. This earth poffeffes the following charaaers : 8. La Tableau Methodique des Mineraux, par M. D'Atibenton. 9. La Mineralogie de M. Ie Comte de BufFon ; in which that celebrated writer has collected a gieat number of valuable facts, whofe merit is inde- pendent of all theory. 10. The Mineralogical Works of Meffrs. Jars, Dietrich, de Born, Ferber, Trebra, Pallas, G-melin, Linne', Dolomteu de SaufTure dc la Peroule, &c. 11. The excellent A:i»ly('csof Stones, published from time to time by Pott, Margraff, Bayen, Bergmann, Gerard, Schecle, Achard, Mongez, &c. Barytes, or Ponderous Earths. 179 i. It is foluble in fix hundred and eighty times its weight of water, at the temperature of fixty degrees of Fahrenheit. Kirwan. 2. It has a penetrating, acrid, and burning tafte. 3. Its fpecifick gravity is about 2,3 according to Kirwan, and 2,720 according 10 Bergmann. 4. It feizes water with great avidity; at the fame time that it falls into powder, increafes in bulk, and emits heat. 5. Acids diflblved it without effervefcence, but with the pro- dua ion of 'heat. 6. The borate of foda, or borax, the oxides of lead, and the phofphates of urine, diffolve it by the blow-pjpe without effer- vefcence. It appears to be infufible alone, as it has refifted the heat .of flame urged by a Stream of vital air.—See the Memoir of Mr. Lavoifier. When it is mixed with acids, it forms a fufible combination ; and k haftens the fufion of aluminous, filiceous, and magnefian earths, according to the experiments of Meffrs. Darcet and Bergmann. II. Barytes, or Pondrous Earth. We are indebted to the celebrated chemifts Gahu, Scheele, and Bergmann for our knowledge of this earth. It has not yet been found exempted from all combination ; but in order to obtain it in a fuitable degree of purity, the fol- lowing procefs may be ufed : The fulphate of barytes, or ponderous fpar, which is the moft uSual combination met with on the eirth, is to be pulverized, and calcined in a crucible, with an eighth part of powder of charcoal: the crucible muft be kept ignited during an hour -, after which the calcined matter is to be thrown into water : it communicates a yellow colour to this fluid, at the fame time that a ftrong fmell of hepatick gas is emitted ; the water is then to be filtered, and muriatick acid poured in : a confiderable precipitate falls down, which muft be feparated from the fluid by filtration. The water which paffes through the filter holds the muriate of barytes, or marine fait of ponderous earth, in folution. The carbonate of pot-affi, or mild vegetable alkali, in folution, being then added, the ponderous earth falls down, jn combination with the carbonick acid ; and this laft principle may be driven off by calcination. 1. Pure barytes is of a pulverulent form, and extremely white. 2. It is foluble in about nine hundred times its weight of dif- tilled water, at the temperature of fixty degrees, according to J£irwan. ?8o Magnefian Earth. Pure Clay. 3. The Prufliate of pot-affi, or Pruffian alkali, precipitates \% from its combination with the nitrick and muriatick acids. This habitude distinguishes it from other earths.—See Kirwan. 4. It precipitates alkalis from their combinations with acids. 5. Barytes expoSed, by Mr. Lavoifier, to flame fed with oxi- genous gas, was SuSed in a few feconds: it extended itfelf upon the furface of the coal; after which it began to burn and deto- nate until the whole was nearly diffipated. This lci»4 of inflam- mation is a charaaer common to1 metallick fubftances ; but when the barytes is pure it is perfectly inSufible.—See Lavoifier. Ponderous earth urged by the blow-pipe makes little efferveS- cence with Soda, but is perceptibly diminished : it diffolves in the borate of Soda with efferveScence, and Still more with the phof- phates of urine.—See the abbeMo'ngez, Manuel du Mineralogifte. 6. Its fpecifick gravity exceeds 4,000, according to Kirwan. III. Magnefia, or Magnefian Earth.. This earth has been no where found difengaged from all for- eign fubftances ; but in order to obtain it in the utmofl poffible State of purity, the cryftals of the fulphate of magnefia, or Ep- fom fait, are to be diffolved in diftilled water, and decompofed fey the carbonate of alkali. The precipitate muft then be cal- cined, to diSengage the carbonick acid. 1. Pure magnefia is very white, very friable, a^id, as it were, fpohgy. _ • 2. Its fpecifick gravity is about 3,3.3, according to Kirwan. 3. It is not perceptibly foluble in water when pure; but when \t is combined with the carbonick acid, it is foluble ; and cold, water has a 'Stronger a£Uon on it than hot, according to the ex- periments of Mr. Butini.. 4. It has no perceptible aaion on the tongue. 5. It flightly converts the tinaure of turnfole to green- 6. TVIr. Darfet has obferved, that a ftjong heat agglutinates it more or lefs ; but Meffrs. De Morveau, Butini, and Kirwan, found that it was not fufible j and the experiments of Mr. La- voifier have proved jthat it is as infufible as barytes and lime. The borate of foda, and the phofphates of urine, diffolve it with effervefcence.—See the abbe Mongez. IV- Alumine, or Pure Clay. This earth is not more exempt from mixture and combination than the foregoing ; and in order to obtain it in a ftate of puri- ty, the fulphate of alumine is diffolved in water, and decompof- ed by effervefcent alkalis. Silex, or Verifiable Earth. lBl f. Pure clay feizes water with avidity, and may then be kneaded. It adheres ftrongly to the tongue. 2. Its fpecifick gravity does not exceed 2,000, according to Kirwan. 3. When expofed to hear, it dries, contraas, Shrinks, and be- comes full of' clefts. A considerable degree of heat renders it fo hard that it gives fire with the fleel. When it has been well baked, it is no longer capable of unit- ing with water ; but requires to be diffolved in an acid, and pre- cipitated, in order that it may refume this property. The experiments of Mr. Lavoifier fhew that pure alumine is capable of an imperfea fufion, approaching to the confidence of pafte, by heat excited by a current of vital air. It is then transformed into a kind of very hard ftone, which cuts glafs like the precious ftones, and which very difficultly yields to the file. The mixture of chalk Singularly affifts the fufion of this earth : it is fufible in a crucible of chalk, according to Mr. Gerhard, but not in a crucible of clay. The borate of foda, and the phofphates of lime, diffolve it.— See Kirwan and the abbe Mongez. According to the experiments of Mr. Dorthes, the pureft na- tive clays, and even that which is precipitated from alum, con- tain a fmall quantity of iron in the ftate of oxide ; and it is from this principle that the earthy fmell which is emitted by moiften- ed clays, arifes : it is very difficult to deprive them of it. V. Silex, or Quartzofe Earth, Vitrifiable Earth, &c, / This earth exifts nearly in a ftate of purity in rock cryftal. But when it is required to be had in a ftate of purity free from all Sufpicion, one part oS fine rock cryftal may be fufed with four of pure alkali. The fufed mafs muft then be diffolved in water, and precipitated by an excefs of acid. r. Pure filex poffeffes a Singular degree of roughnefs and af- perity to the touch. It is absolutely void oS all difpofition to ad- here ; and its particles, when agitated in water, fall down with extreme facility. 2. Its fpecifick gravity is 2,65 3. Bergmann had affirmed that water might diffolve it; and Mr. Kirwan has pretended that 10,000 parts of water might hold one of filex in folution, at the ordinary temperature of the atmofphere ; and might even take up a greater quantity at a higher temperature. The fluorick acid diffolves it; and lets it fall when it comes in contaa with water, or when it is considerably cooled. 182 Calcareous Saline Stones. 5- Alkalis diffolve it in the dry way, and form glafs ; but they attack it likewife in humid way, and are capable of diffolv* nig one Sixth part oS their weight when it is in a ftate oS extreme divifion. 6. The burning mirror does not fufe it j but a current of vi- tal air produced a commencement of fufion on its SurSace.—See Lavoifier. Before the blow-pipe foda diffolves it with efferveSence. The borate of Soda diSTolves it flowly, and without ebullition. CLASS I. Concerning the Combination oS Earths with Acids. This claSs, which comprehends the combination of primitive earths with acids, naturally exhibits five genera. GENUS 1. Earthy Salts with Bafis of Lime. The combination of lime with various acids affords the fever?* al fpecies of calcareous Salts comprehended in this genus. sjpecies i. Carbonate of Lime, or Calcareous Stone. / The combination of lime with the carbonick acid is very com-r monly met with, and comprehends all the ftones which have hitherto been diltinguithed under the names of lime-ftone, cal- careous ftone, Sec. The characters of the carbonates of lime are—i. They ef- FerveSce with certain acids. 2. They are converted into lima by calcination. The Formation of theSe ftones appears to us to be Sor the moft part, owing to the wearing down oS Shells. The identity of the conftituent principles oS Shells and calcareous ftones, and the preSence of thefe fame fbells, more or lefs altered, in the lime-ftone mountains, authorize us to conclude that a great part at leaft of the calcareous mafs of cur globe owes its origin to this caufe only. Though our imagination appears to affent with difficulty in reSerring effeas oSSo wonderfully extenfivc a nature to a caufe Cryfiallized Calcareous Stones* I&3 apparently fb weak, we are compelled to admit it when we take a Slight view of the known hiflory of Shells. In faa, we obferve the numerous clafs of fhell animals which poffefs this ftony covering almoft at the inftant of their origin. We fee it infenfibly become thick and enlarged by the appofition oS new coverings ; and this fhell at length comes to occupy a volume fifty or fixty times larger than that of the ani- mal which produced it. Let us confider the prodigious num- ber of animals that emit this ftony tranfudation ; let us attend to their Speedy augmentation, their multiplication, and the Short period of their life, the mean term of which is about ten years, according to the calculation of the celebrated Buffon ; let us multiply the number of thefe animals by the mafs of fhell they leave behind them—and we fhall then arrive at the mafs which the Shells of one fingle generation ought to form upon this globe. If we proceed further to confider how many genera- tions are extinct, and how many fpecies are loft, we Shall be no longer furprized to find that a confiderable part of the furface of the globe is covered with their remains. It may eafily be conceived that thefe fhells when carried along by currents of water, muft ftrike together and wear their refpeaive furfaces •, and that their pulverulent remains, after being long carried about and fufpended by the waters, muft at laft fubfide, and form heaps or banks of fhells, more or lefs al- tered according to circumftances. But whatever may be admitted as the origin of this ftone, it is found to exift in two principal ftates ; that is to fay, either in the Sorm of cryftals, or of irregular mafles. I. Cryftallized Calcareous Stones. A concurrence of circumftances which very Seldom meet to- gether, is required, in order that cryftallization may take place. This is doubtless, the reaSon why Spars and calcareous cryftals compoSe the Smalleft part of this genus. The cryftals are found in cavities of calcareous mountains ; in the clefts which penetrate into the internal part of ftones of this clafs ; and gen- erally in all places where waters find accefs, after having worn down calcareous ftone to a ftate of extreme attenuation, nearly corrcfpondent to folution. Calcareous ftone, in its cryftallized ftate, prefents us with feveral varieties of form ; but the rhomboidal figure appears to be the moft conflant and the moft general. The environs of Alais abound with rhomboidal fpars of the greateft beauty -r they are tranfparent like thofe of Iceland, and double objeas ia the fame manner. * ?4 Calcareous Stones not Cryfla/lized, It often happens that a group of rhomboidal cryftals exhibits' at its SurSace a number of pyramids more or lefs prominent, which confift of the angles of rhomboids of different degrees of length. It cannot but be admitted, with Mr. Rome" de Lifle, that the pyramidal form is a flight modification of the rhom- boid ; for rf a pyramid of Spar be broken, it is reduced into ele- ments of a rhomboidal figure. The principal varieties of the pyramidal form are deduced more efpecially from the number of their Sides ; and when the pyramid is long and Sharp, it is called dog-tooth fpar, or hog- tooth fpar. Calcareous ftones often affea the prifmatick form; and this is likewiSe attended with Some varieties. The prifm is frequently fix-fided and truncated ; fometimes it is terminated by a trihedral pyramid ; and when the prifm is very Short, and its Summit is almoft entirely in contaa with the ground, the cryftal is known by the name of Lenticular Spar. All the varieties of form which cryftallized calcareous Stones have hitherto prefented, may be Seen in the Cryftallography of Mr. Rome de Lifle. The fpecifick gravity of calcareous Spars is about 2.700 when pure, according to Kirwan. They contain Srom thirty-four to thirty-Six parts of carbonick acid, and from fifty-three to fifty-five of earth ; the'reft is water. -'—See Kirwan. Spars often exhibit a Smooth uniform furface, upon which the fulphurick acid takes but flight hold : they are fometimes contaminated with iron, which gives them Various tinges. II. Calcareous Stones which are not cryftallized. Few calcareous ftones affea any regular form : they lie al- rnoft always in ftrata, or immenfe blocks thrown or heaped to-: gether on the furface of the globe, in which we cannot reason- ably pretend to difcern any primitive defign of cryftallization. The notion itSelS which we have of the formation of thefe mountains, and the ftratified difpofition of their parts, does not allow us to difcern any other effea than the natural conSequence of the flowing of water, which muft have occafioned a contrac- tion, and difpofed the rocks in Strata or beds. It Seems to me that two very natural divisions may be eftab- liflied among calcareous ftones which are not cryftallized : Sor they are either SuSceptible of a perfea polifh, in which cafe they are called marbles and alabafters ; or they are not fufeeptible of this polifh, in which cafe they are called friable earths, tufa, Sec. Calcareous Stones. Marble. ig< A. Calcareous ftones fufceptible of aperfea polifh. Although it be proved from the experiments of chemifts, and more efpecially from thofe of Mr. Bayen, that marbles contain a greater or lefs proportion of clay, we are under the neceflity of placing them here : becaufe the calcareous earth predomi- nates to fuch a degree, that they cannot with propriety be placed elfe where ; and becaufe they poffeSs all the charaaers of lime- ftone. Marbles differ from other calcareous ftones by the polifh o£ which they are fuSceptible ; and they are distinguished Srom each other by their colours. White marble is uSually the pureft. We are acquainted with the marble of Carrara, and the ancient ftatuary marble of Paros. Black marble is coloured either by bitumen or by iron. Mr. Bayen found this metal in the proportion of five parts in the hundred. When it is veined by pyrites, it is called Portor. There are an infinite number of varieties of coloured marble. The colouring part is in general owing to the alterations of the iron, which is fometimes obedient to the magnet, according to an observation of Mr. De Lifle. Blue and green marbles owe their colours to a mixture of fchorle, according to Rinmann in his Hiflory of Iron. The marble which prefents the figure of Shells appears to be formed fimply out of a heap of fhells conneaed by a calcareous cement ; it is known by the name of Lumachello. That o£ Bleyberg in Carinthia forms one of the moft beautiful fpecies. The marble which is called figured marble, exhibits either traces of vegetables, as that of Hefl'e ; or ruins and rocks, like that of Florence. The dendrites appear to be formed merely by ferruginous infiltrations through the cracks of thefe ftones. Several naturalifts have mentioned flexible marble. Father Jac- quier deScribed this in 1764, in the Gazette Litteraire ; and the abbe De Sauvages has communicated to the Academy of Mont- pellier a defcription of the plates of flexible marble which are in the Palais Burgeon;. Alabafters are calcareous ftones of the nature of marble : they appear to be formed like the ftalaaites, and are fometimes a- dorned with the moft beautiful colours : thefe in general poffeSs a certain transparency, with a Stratiform texture varioufly col- oured, and caufe a double refraaion of the light when they are Sufficiently transparent. In the treatiSe of Mr. Briffon on the Specifick gravity of bodies, the reader will find the refult of his valuable experiments on that of marbles, sdabafters, and general- ly all the calcareous ftones. iM Calcareous Stines. B. Calcareous Stone not fufceptible of a perfea poliffi. Calcareous ftones which are not fuSceptible of a perfea polifh,* are found either in maffes* or in the pulverulent form ; which circumftance will afford a foundation for our natural diftinaion. i. Solid calcareous ftone is in general the ftone ufed for build- ing ; and this is found in feveral varieties, differing in finenefs of grain, porofity,- colour, cohfiftence, or weight : Thefe are gradations which eftablifh the feveral qualities of ftones ; and1 are the caufe why one hardens in the air, while another is de- compofed' On thefe Several accounts it is that the refpeaive varieties are applied to various uSes ; and it is the bufinefs of the' Skilful artift who ufes them to diftinguifh their qualities. In the number of thefe ftones ufed for building, there are fome which imbibe and retain water, in confequence of which they are bur ft or crumbled by the froft ; whereas others Suffer the water which they originally contained^ to eScape and become harder by the contaa oS the air. 2. Calcareous ftone is fometimes found in the pulverulent form; Chalk is of this kind ; and wherrrt is white, and very finely divided, it is Sormed into thoSe maffes known in com- merce by the name oS Spanish White. For this purpoSe it is agitated in a vefltl with water. The foreign Substances, Such as flints,, pyrites, &c. are precipitated ; the water is then decant- ed ; and the chalk, which is held SuSpended, very foon fubfides : this is dried, and divided into long fquare pieces, to form the Spaniffi White. When a natural ftreatn of water Wears away this chalk, and afterwards depofites it, the refult has been distinguished by the name of Gurrh ; and when this poffeffes a certain confiftence, arifing from the mixture of argillaceous artd magnefian earths, it is diftinguiflied by the name of Agarick Mineral. As calcareous earth is fufceptible of extreme divifion, the wa-- tfer which wears it away, and is aSterwards filtered through the" clefts in rocks, depofites it gradually, and forms thofe incrusta- tions known by the vulgar under the name of Petrefaaions, and by that of Stahaites among naturalifts. Thefe calcareous depofitions very frequently preferve the form of fuch fubftances as they have covered, and prefent figures of mofs, roots, fruit, &c. which has given rife to an opinion that thofe fubftances were transformed into ftone. The increafe of flalaaites, being accomplished by addition tc their external furfaces, their texture exhibits concentrick coats of different fhades, accordingly as the water may have becft^ charged with different colouring principles. Calcareous Stones ,187 The cavities which are frequently Sound in calcareous moun- tains are oSten lined with ftalaaites ; and thefe grottos form one of the moft Striking appearances which can prefent itfelf to the eyes of the naturalift! The grandeur of thefe fubteraneous places,the abfence.of light, the feeble glimmering of a torch, which only half enlightens the Surrounding objeas, render thefe regions gloomy, majeftick, and impofing. The multiplicity of figures, the variety of forms, ,and their refemblance to other objeas, never fail to caufe a high degree of aftonifliment in the mind of the mineralogical ftudent. Among the infinite number of thefe forms, tliere are Some which are very agreeable, Such as /the flos Serri, cauliflowers, lace, or fringes. Other very Singular figures are Ujkewif'e Sound, Such as the priapojithes, piSoJithes, polithes, .&c. Mr. Lougeon of Ganges has obferved, in the grotto called Des DemoiSelles, a number of forms fo varied and Strange, as to exhibit a very aftonifhing colfeaion. Thefe transudations, .or rather thefe ftony depofitions, have given rife to a belief in the vegetation of ftones. The celebrat- ed Tournefort was of opinion that he had obferved nature in the very faa, in the famous grotto of Antiparos, where he faw in- scriptions engraved ,in the ftone, hut afterwards converted into reliefs. Baglivi has written a treatife on the vegetation of ftones, 4n which he cites many facts of this nature. All the world is acquainted with the depofitions of the fpring in the vicinity of Clermont ; hut the moft furprizing of all pet- f efying waters is that of Guancavelica in Peru. Barba, D. Ulloa and Frezier, have given us a defeription of it. Feuille informs us that this water rifes very hot in the middle of a fquare ba- fon, and becomes petrefied at a fmall diftance from the fpring. fhe water is a yellowifh white, and the incruftations have been uSed to build the boufes of Guancavelica. The workmen fill moulds with its water and Some days aSterwards they find them intruded with this ftone. The ftatuaries expoSe their moulds in this Spring, and have only to give the polifh in order to ren- der their flames transparent. All the ftatues uSed in religious ceremonies, by the catholicks of Lima are oS this Subftance, and are very beautiful—Journal des ObServ. torn. i. 434. In the year 1760, Mr. Vegni devifed a method of making a Similar uSe of the very white chalk which is contained in the wa- ters of the baths of St. Philip in Tufcany. For this purpofe the water is fuffered to run for the fpace of near a mile, in order that it may depofite the fulphur, the Selenite, and the tufa which it contains ; and in this purified ftate it is ufed in the fabrica- tion oi bas reliefs. It is introduced at the«oof of a building, *<** Fabrication of Lime. into a clofet conftruaed of planks fitted together. The water falls Srom twelve to fifteen feet in height, upon a wooden crofs placed on a poft ; by which Sail it is divided, and daflies late- rally againft Sulphur moulds, which are placed on the fides of the cabinet In this way it depofites the particles of the earth which it contained, and the mould becomes filled. Mr. Vegni placed the moulds upon pieces of wood which are moved cir* cularly. This alabafter is as hard as marble ; and the incruf- tation is more beautiful, and harder, in proportion as the posi- tion of the mould is more vertical., and its. diftance greater. The Analyfis and Ufes of Calcareous Stone, In 1755, Dr. Black proved that calcareous ftone poffeffes, as one of its component parts, an air different from atmofpherick air. He afferted that calcareous ftone when deprived of this air by calcination, forms lime ; and that lime might again pafs to the ftate of calcareous ftone by refuming the principle it had been deprived of. In 1764, Macbride fupported this doarinc by new faas. Jacquin added other experiments to thefe ; and proved that lime and alkalis owe their caufticity to the Subtrac- tion of this fixed air, at the fame time that he pointed out fev- eral methods of depriving them of it. The proceffes which are moft commonly ufed for the de- composition of lime-ftone, are fire and acids ; the firft is ufed in the making of lime ; the fecond in laboratories, when it is intended to procure the carbonick acid. In order to form lime, the calcareous Stone is calcined in fur- naces, whofe conftruaion is varied according to the nature of the oombuftibles made uSe of. When pit-coal is ufed, an inverted cone is conftruaed of vitrifiable ftone, which is filled by alternate Strata of coal and lime-ftone ; and the lime is taken out, after the operation, by an aperture at the top. In proportion as the mafs Subsides, care is taken to Supply the furnace at the top, in order that the fiame and heat may not be loft. Bergmann has obferved that moft fpecimens of calcareous ftone which become black or brown by calcination, contain manganeSe, and that the lime which they produce is excellent. According to Rinmann, the white calcareous ftones which become black by calcination, contain about one tenth part of this fubftance. Calcination deprives limerftone of the acid and water which it contained. Thefe two principles are evidently replaced by the matter, of heat itfelf* The odourof Sire, which quick-lime emits; Lime Water and Lime. 18$ the light which it affords when Slackened in a dark place ; the colour which it communicates to the lapis caufticus; the prop- erty which it poffeffes oS producing the oxide and the piaffes of lead—all prove to us, as Mr. Darcet obServes in the Journal de Phyfique for 1783, that in proportion as the calcareous ftone js deprived of the aeriform principle, it combines with the ig- neous principle, which cannot be difplaced but by the way of affinities. The beautiful experiments of Meyer, when divefted pf all theory prove the fame thing. It is proved, from the experiments of Dr. Higgins, that the belt lime is that which is made with the hardeft and moft com- paa ftone broken into fmall pieces, and heated flowly, until the furnace is become of a white heat. This heat muft be kept up until the Stone is no longer capable oS efferveScing with acids. The lime becomes over-burned if the ignition be carried to a greater degree; and the produce is then a frit, which is no longer capable oS being divided in water, or oS reSuming with avidity the principles it had loft. When pieces of calcareous ftone of different Sizes are cal- cined, the lime will not all be of equal goodneSs ; the Small pieces confitling of ovcrrburned lime, while the larger pieces are fcarce- ly altered in their central parts. The bell lime is that which is the moft quickly divided by immerfion in water, and affords the greateft quantity of heat in this procefs, which caufes it to fall into the fineft powder. Good lime fhould likewife diffolve in the acetous acid without effervefcence, and leave the leaft poffible quantity of refidue. Lime continually endeavours to refume the acid and the wa- ter of which the ftone was deprived by calcination: consequent- ly, when it is left expofed to the air, it cracks, becomes heat- ed, falls into powder with an increafe of bulk, and refumes the property of effervefeing. It is therefore of importance to ufe lime newly made, if the artift be defirous of poffeffing its whole force. Lime is fparingly foluble in water, and this folution is called lime-water ; the lime may be precipitated by means of carbon- ick acid, which regenerates calcareous ftone in the form of a precipitate. Lime-water is ufed to indicate the prefence, and determine the proportion, of carbonick acid in any mineral water. Phyficians prefcribe it as an abforbent and detergent. When lime-water is left in contaa with the air of the atmof- phere, a pellicle is formed at its furface, known by the name of the cream of lime ; this is the regenerated calcareous ftone. The fuperb bafon of Lampi, one of the two principal refer- voirs which furnifh the Jjtoyal Canal of Languedoc with water, ?9® Mortar cf.the Ancients, was found to leak at the junction of the ftone?. The fkilf'4 engineer who direas theSe works, Mr. Pin, caufed lime to be flacked ; which, paffing through thefe fmall apertures, became fupplied with carbonick acid, and formed a cruft, or very white covering, over its whole furSace : So that all the ftones of this, fine piece of maSonry are conneacd together by this cement j aad at prefent conftitute one fingle undivided fubftance, impen- etrable to water. The regeneration of calcareous ftone is very flowly effeaed by the proceffes hitherto defcribed. But this may be expedited. by preSenting to die lime the principles with which it So ftrong- ly tends to combine : this 4$ accordingly done in, works in the large way. Lime is ufually flacked by pouring abundance of water upon It. A violent heat is thus excited ; the lime falls down into powder, and a pafte is afforded by ftrongly working the lime to- gether in proportion as it becomes Saturated. The count Razoumoufki has taken advantage of the heat which is difengaged when lime, 13 flacked, to combine the lime with Sulphur. The degree of heat proper to eSfea this combination is 70 of Reaumur. At this point the Sulphur^ which is placed in contaa with the lime, liquefies, becomes of a red colour, and forms a true fulphure or hepar of lime. Mortar is made Simply by working fand, or other bodies inSc* luble in water, together with flacked lime. We are acquainted with two kinds oS fand at Montpellier j pith Sand, and river Sand : .the former "is almoft always alte«4 by a mixture of vegetable and calcareous earth, which weaken its efficacy ; the fecond is purer, and better fuited for the pur. pofe. Inftead of fand, the fragments or dull of ftone may be ufed ; the angles which thefe fragments prefent, and the rough- n.efs of their furface, contribute to give a confiftence to the mor- tar. The hardening of mortars appears to be owing merely to^thc. progreflive regeneration of lime-fton.j. They do not obtain the greateft degree of hardnefs of which they are fufceptible, until they have reSumed all the carbonick acid oS which the ftone was deprived : and this operation is very flow, unleSs the combuftion be facilitated by well known methods, whiph confift in mixing Subftances with the mortar which contain either the carbonick acid, or a principle analagous to it, Such as vinegar. * It is this regeneration oS lime-ftone, which is effeaed by the bupSe oS time, that explains to us why the hardelt ftones afford the beft lime ; and why old mortars are Sound to poffefs a degree of hartlnefs which modern artifts have no hopes of attaining. Plafter Shne. \*> $ The remains of ancient buildings have induced certain philof- ophers to conclude, that the ancients were in poffeffion of very valuable proceffeei for the making of mortar. Mr. De la F-iy« was of opinion^ that thofe enormous maffes, in which the per- fection of the mechanical proceffes of the ancients only was ad- mired, were made by coffer work; and he imagined that he had difcovered in Vkruvius, Pliny, and St. Auguftin, that their pptji. Cefs to extinguiftt lime differed from ours; and that the grea£ difference which appears lo exift between the ancient and mod- ern mortars depends more particularly upon this circumftance. Thefe mtereftirrg refearches have induced him to propofe that the lime Should be put into a bafket and Suffered to flack in th€ air; as he thinks-by this means it would preferve a greater de- gree of force, and b£ lefs weakened than by the ufual proceffes/ Loriot has attributed the fuperiority of the mortars of the ancients to the means which they ufed to dry them fpeedily $ and in confequence of thefe principles he mixes pounded bricks with flints, works the whole together with flacked lime, and dries the mafs with one fourth part of quick-lime. Care rrftift be taken to ufe-only lime which is finely pulverized and Sifted $ for otherwife the mortar would cracky and be very imperfea. Nature Sometimes preSerrts tons a fuitable mixture of lime-r ftone and fand, to form an excellent! mortar without any mix- ture of extraneous fubftances. Mr. f3e Morveau found this* lime-Sfcne in Bnrgundy ; Mr. De Puymaur'm has deScribed a fpecies which he found in Berne ; and I have obferved in Cev- ennes a natural mixture of this kind,'in which the proportion of? materials was fo well afforted, that nothing more was neceffary than to calcine it, and extinguish it in water, to form an excellent? mortar. • SPECrES 11. Sulphate of Lime, Gypfum, Selenite, Plafter Stone. The Plafter Stone lofes its transparency by calcination, at the Same time that it becomes pulverulent, and acquires the pro- perty of agai«f*feizing the water of which it had been deprived, and refuming its hardnefs ; it does not give Sire with the Steel, nor effervefce with acid's. We are more particularly indebted to Margraff Sor our ac- quaintance with the conftituent principles of plafter ; and 'from fubfequent experiments the following proportion of the fame principles has been affigfted. One hundred parts of gypfum contain thirty Sulphurick acid, thirty-two pure earth, thirty- eight water ; it lofes nearly 20 per cent, by calcination. *92 Natural Hiflory of Plafter, We begin to be equally acquainted with the formation of this ftone. The chevalier De Lamanon has afferted, that the numerous quarries oS plafter which are found in the vicinity of Paris, are the deposition of an ancient fluviatile lake, formed by the Seine, LoiSe, and Marne, which flowed off on the fide of Meulan. The wrought iron, and the various remains oS animals which are found at the bottom of the quarry of Mont Matre, fhew that its formation is not very ancient; and the indefatiga- ble naturalift here cited confiders the felenite as originally dif- perfed in the water, precipitated in confequence of its fparing folubility, and heaped together in places determined by currents, waves, and other circumftances. Thefe faas, highly interefting as they are in the natural his- tory of plafter, are infufficient for the chemift, who is defirous of knowing likewife in what manner, and under what circum- ftances, the combination of the fulphurick acid and lime is made I Shall proceed to communicate fome obfervations which our province affords. I. I have obferved in a black and pyritaceous clay of Saint Sauveur, extraaed out of the work called Percement Dillon, many fmall needle-formed cryftals of felenite, from four td eight lines in length. At the furface of the foil where the fame clay is more decompofed, cryftals of the fame nature, but lon- ger, thicker, and more numerous, are alfo found. 2. The marly and pyritous clay, of Caunelle, near Moffon, abounds with beautiful cryftals of rofe-coloured plafter, in the form of cocks-combs, obferved by Mr. Dorthes. y. The plafter quarry oSLa Salle exhibits almoft alternately Strata oS plafter and Strata of black and pyritous clay, which efflorefces in the air. 4. Near the bridge of Herepian, on the* declivity of Cafcaf- tel, at Gabian, and in many other places, 1 have conftantly Sound cryftals oSgypSum mixed and confounded with pyritaceous clays. 5, The Sulphureous depofitions of folfatara often contain •ryftals of felenite. From thefe. faas it appears to me that.the formation of gyp- fum may eafily be conceived. It is not formed excepting in places where pyrites and clay more or lefs calcareous are found together : that is to fay, its formation appears to be dependent on, and conneaed with, the prefence of fulphur and lime. Whenever, therefore, the pyrites is decompofed, the fulphur- ick acid which thence arifes feizes the lime, and efflorefces in fmall cryftals, which are carried off by the water, and fooner or later depofited. I have obServed perceptible depofitions of plafter on the banks of rivulets which wafh pyritous clays. I Formation and Habitudes of Gyfffum: iej have likewiSe Seen depositions of the. Same nature in rivers whoSe waters have been ftrongly concentrated by the burning heat of our Summer. And consequently, if we fuppofe felenite to be difperfed in more confiderable maffes oS water, there will be no difficulty in conceiving the Sormation oS thoSe ftrata which the plafter quarries exhibit. , Meffrs. De Cazozy and Macquart have obServed the trafition of the gypfum of Cracovia to the ftate of calcedony. When the nucleus of calcedony is determined it increafes perceptibly in the courfe oS time, even in cabinets ; which proves that the quartzoSe juice, when once infiltrated into plafter, combines with the lime, and determines this transformation. Mr. Dorthes has proved that the quartz,, in cocks-combs at Paffy, owed its origin to plafter ; that this laSt Subftance having been carried away by Solution, the quartzoSe juice has taken its place. Natural hiflory exhibits Several oS theSe metamorphoSes. Gypfum is found in the earth in Sour different ftates. i. In the pulverulent and friable Sorm, which conftitutes gypSeous earth, Soffit flour, &c. 2. In Solid maffes, which conftitute plafter-ftone. 3. In ftalaaites, or Secondary depofitions. In this place we may arrange the ftriated Silky gypSums, the cauliflowers, the gyp- Teous alabafters, and that prodigious variety of forms which the ftalaaites affumes, whatever may be its component parts. 4. In determinate cryftals which uSually exhibit the following forms... r. The compreffed tetrahedral rhomboidal prifm. 2. The hexahedral prifm truncated at its Summit. 3. The decahedral rhomboid. I apprehend that the lenticu- lar gypSum may be referred to this laft form, as it appears to me to be compoSed oS Several rhomboids united together fide- ways. At all events I have^ as the laft reSult, obtained the rhomboidal Sorm, by decompofing this variety. The colour of gypSum is Subjea to a great number of varie- ties, which are the Signs oS various qualities relative to its ufes,; The white is the moft beautiSul, but Sometimes it is grey ; and in this caSe is leSs efteemed, and leSs valuable. The Several ftates oS the oxides of iron, with which it abounds in greater or lefs quantities, conftitute its rofe-coloured, red, black, Sec. varieties. The Specifick gravity of gypSum varies according to its purity. See Meffrs. Briffon and Kirwan : the latter Sound it Sometimes of the weight oS 2.32, and Sometimes 1.87. It is Soluble in about five hundred times its weight of water, at the temperature of 60 degrees of Fahrenheit. 2...A tyf Filiate of Lime or Fluor Spar. When it is expofed to heat, its water of cryftallization is diflft- pated, it becomes opake, lofes its confiftence, and falls into pow- der. If it be moiftened, it becomes hard again, but does not refume its transparency; a circumftance which appears to prove that its firft ftate is a ftate of cryftallization. If it be kept in a fire of confiderable intensity, in contaa with" powder of charcoal, the acid is decompofed, and the refidue is lime. Its principles may likewife bfe Separated by finely pulverizing k, and boiling it with alkali. It is fufible by the blow-pipe according to Bergmann ; and In' a porcelain furnace, according to Darcet. The management of the fire in the calcination of gypfum is" of great conSequence. Too much heat decompoSes it; and too Httle does not enable it to unite, and form a hard fubftance with water. Calcined gypfum divides and diSperfes itfelf in water, with which it forms a pafte that may be call into every figure imag- inable. We are indebted to this property for beautiSul orna- ments in the irifide of our houfes ; but it cannot be ufed for external decorations becaufe, its folubility in water renders it gradually deftruaible by that liquid. SPECIES nf. Filiate of Lime, Vitreous Spar, Fufible or Phofphorick Spar, Fluor Spar. This ftone is a combination of a peculiar acid, called the fluor acid, with lime. It decrepitates on heated coals, like muriate of foda, or com- mon fait. When flightly heated, it fhines with a beautiful blue colour, that remains even under water, or in acids. The refi- due of this appearance of combuftion is white and opake. Its fpecifick gravity is, in general, from 3.14 to 3.18, accord-1 ing to Kirwan. This fpar enters into-fufion by a Strong heat, and corrodes the the Crucible: it likewiSe SuSes without efferveScence with the mineral alkali, the borate of Soda, and the phoSphates of urine. . This ftone pofleffes the moft lively and various colours ; and it is known under the names of falfe emerald, falfe amethyft, or falfe topaz, accordingly as its colour is green, violet, or yellow. The blue fluor fpars commonly owe their colour to iron, but fometimes to cobalt. Berlin Berchaft, torn. ii. p. 330.—Green fluors are coloured by iron, according to Rinmann. The moft ufual form of fluate of lime is the cubick, with all the modifica-' tions which accompany their primitive form. Properties and Habitudes of the Acid Fluor. 10$, When this ftone is diftilled with its own weight of fulphurick acid, the firft produa confifts of elaftick whitifh vapours, which jill the receiver, and depofite a cruft at the furface of the water, while the water itfelf becomes acidulous. The refidue in the retort is fulphate of lime, according to Scheele. The cruft which is formed on the water of the receiver is filiceous earth -t and the water itfelf being Saturated with the vapour, constitutes the fluorick acid. The moft aftonifhing property of this acid is doubtlefs that of feizjng the filiceous earth, wbich is a conftituent principle .of the glafs, and volatilizing it with itfelf. In order to have the acid in a ftate of greater purity, and ex- empt from every mixture of filex, the operations are performed in retorts of lead ; but Mr. De Puymaurin-is convinced, as well as myfelf, that the acid even then is Seldom pure, becaufe the moft beautiful fluor contains almoft always a Small quantity of filex, which the acid carries with it. The whiteft, the moft rranfparent, and the moft regularly-cryftallized fluor, diftilled on the water bath in a leaden retort, afforded me an acid contanuV nated by a Small quantity of filex. Mr. Meyer having ufed every poffible means to obtain this acid in a ftate oS great purity, is Convinced that when the acid does not find filex i» the retort, it attacks the fides of the re- ceiver, and becomes changed. This acid may be preServed in bottles whofe internal Surfa- ces are coated with wax diffolved in oil. The fluorick acid has Some analogy with the muriatick; and fome chemifts have even confounded them together : but they differ effentially Srom each other. The fluorick acid—1. When combined with pot-affi, preSents a gelatinous Subftance, which when dry retains one fifth of the alkali employed, and forms a true neutral fait. 2. It aas near- ly in the fame manner with foda. 3. With ammoniack it af- fords a jelly, which when dry exhibits all the appearances of filex. 4. When mixed with lime-water, it regenerates the flu- ate of lime. 5. It does not attack gold, nor diffolve filver; and combines in preference with oxides, fuch as thofe of lead, iron, copper, tin, cobalt, and even of filver. One part of the fluate of lime, fufed with four parts of cauf- tick fixed alkali, forms a fait infoluble in water. The fame quantity Of fluate of lime, treated in the fame manner with the carbonate of pot-afh or mild vegetable alkali, affords a foluble fait; and at the bottom of the water a calcareous earth is found, which proves that the fluorickacid is not feparated but by double- affinity. '*£$ Nitrate of Lime. This ftone which hitherto has not been employed but as a flux, or in the fabrication of ornaments, appears to me to deferve1 the moft particular attention. Its texture feems to be lamellaf- Cd like the diamond ; and like that ftone it is Capable of double . refraaion, as the abbe Rocbon has obServed. Its phoSphoreS- Cence has likewiSe Some relation with the combuftibility of the diamond, and it has lively and varied colours- All thefe cir- cumftances eftablifh an analogy between theSe two Subftances ; and might'lead us to SuSpect: that the constituent principles of the diamond exift in this Shone, mixed and combined with ah acid and lime, &c. 'l- The fluorick acid poffeffes the very Singular property of attack- ing glaSs, and diffolving' and carrying' off its filiceous part. Margraff firft obferved this property; but Meffrs. De Puymau-F rin and Klaproth have very happily applied it to the art of en- graving orl glafs. '>■>•,■ * > ... This acid is employed to corrode the glaSs, in the Same man- ner as aqua fortis is uSed to engraveupoh Copper. Some-authors, particularly Mr. Monnet, have endeavoured to prove that this acid was nothing elSe but a modification of fhe acid ufed in the decompofition of the fpar. They Seem to found'their opinion chiefly on the circumftance, that the acid Obtained'exceeds in weight the fpar made ufe of ; but they have negfeaed the increafe of weight which muft arife from the erofioiii diflblution, and mixture of the glafs of the diftilling vef- fels. And indeed thefe experiments do not appear to me to in- validate in the leaft the eternal truths which have iffued from the laboratory of the celebrated Scheele ; otherwife fuch modi- fications in the acids employed, would in my opinion afford a; phenomenon ftill more aftonifhing than the exiftence of this pe* culiar acid. •.......... SPECIES IV. Nitrate of Lime, Calcareous Nine. This fait, as well as thofe which remain to be treated of in the prefent genus, exifts only in waters. Their great Solubili- ty, and their Spontaneous deltqueScence, do not permit them to form durable maffes, or to exift in the form of ftones. The nitrate of lime is principally formed near inhabited pla- ces ; old plafter affords it in abundance by lixiviation. It is one of the falts which abound in the mother waters of the falt-petre makers; and it has been Sound in Some mineral waters. It is uSually obtained in the Sorm of fmall needles, applied Sideways to each other. ii-* ■ "■ Calcareous Marine Salt. l91 When a Solution of nitrate of lime is concentrated to a gelatinous confiftence nearly equal to that of fyrup, it forms in procefs of time, cryftals in hexahedral prifms. Two parts of cold water diffolve one of this Salt; and boiling water diffolves more than its own weight. Its tafle is bitter and diSagreeable. It liquefies eafily on the fire, and becomes Solid by cooling ; if it be ftrongly calcined, and carried into the dark, it is lumin- ous, and constitutes Baldwin's phofphorus. It lofes its acid in a violent and continued heat. When dif- tilled in clofe Veffels, it affords the fame produas as nitre by the decomposition of its acid. Projeaed upon ignited coals, it detonates in proportion as it becomes dry.-^-See De Fourcroy. Its acid may be difengaged by means of clay and of the ful- phurick acid. The alkalis and barytes precipitate its earth. The fulphurick falts, and the carbonates of alkali, decompofe it by double affinity. * SPECIES V. Muriate of Lime, Calcareous Marine Salt. This combination exifts more efpecially in the waters of the fea; and contributes to give to thefe waters that bitter tafte which has improperly been referred to bitumens that have no exiftence. This fait is very deliquefeent ; one part and a half of water diffolves one of this Salt; and hot water diffolves more than its Own weight. • It may be made to cryPcallize by concentrating its Solution to the 45th degree of Baume, and expofing it afterwards in a cool place. With thefe precautions it affords a fait in tetrahedral prifms terminated by four-fided pyramids.—See de Fourcroy. It enters into fufion with a moderate heat; but is decompofed with great difficulty. It acquires by calcination the property o£ Shining in the dark, and is called the phoSphorus oS Homberg. It is decorhpoSed by barytes and the alkalis. The concentra- ted Sulphurick acid, poured upon a very ilrong Solution oS mu- riate of lime, difengages the acid in vapours, and Sorms a Solid precipitate : an appearance which Seems in an inftant to trans- form two liquids into a Solid, and produces a very ftriking ef- fea. The theory of this phenomenon is eafily deduced from the very great folubility of the muriate, and the almoft abfolute JnSolubility oS the Sulphate which takes its place. j:c;8 Calcareous Phofphorick Sal/. SPECIES vi. Phofphate of Lime, Calcareous Phofphorick Salt. This phofphate of lime has been found in Spain, in the king- dom of Eftramadura. by Mr. Bowie. It is a whitifh ftone of confiderable denfity, not hard enough £o give fire with the fleel. It is found in horizontal ftrata, re- pofing upon quartz, and exhibiting vertical, flattened, and clofii fibres. When thrown on ignited coals it does not depcrepitate, but burns quietly, and affords a beautiful green light, which Seems to penetrate through it, and does not diSappear So quickly but that a Sufficient time is admitted to contemplate its brilliancy with admiration. BeSore the blow-pipe it runs into a white enamel, without boiling up ; whereas bones Support the moft violent heat without fufion, Its habitudes with the nitrick and fulphurick acids are the fame as thofe of calcined bones : its acid may be feparated and brought into the State of an. animal glafs ; it may be decompofed, and the phofphorus extraaed. Mr. Prouft, Srom whom we borrow theSe interefting details, obServes likewiSe that this ftone is found to compofe the mafs of entire hills in the neighbourhood Of the village of Logrofan, in the juriSdiaion of Truxillo, a province of Eftramadura. The houfes and the walls of inclofures are built of it. GENUS u. Earthy Salts with Bafe of Barytes. The moft common ftate in which Barytes is found is in com- bination with the fulphurick acid. SPECIES I. Sulphate of Barytes, Ponderous Spar. This ftone is the moft ponderous we are acquainted with. Its fpecifick gravity is commonly from 4 to 4.6. It decrepitates in the fire, melts before the blow-pipe without addition, and fluxes diffolve it with efferveScence.—See the notes of the abbe Mongez.* Mr. Darcet Succeeded in Sufing it in a porcelian furnace. * Manuel du Miaeralogifl;. Ponderous Spar. IQ? ft has been often confounded with gypfum and fluor fpar; but the charaaers oS theSe two Subftances are very different. It almoft always accompanies metallick ores, and it is even confidered as an happy preSage of finding them. Becher has affirmed that it was a certain indication vel prefentis vel futuri metalli : and I think that there is reafon to confider it as the vitrifiable ftone of this celebrated naturalift. The proofs of my affertion may be feen in the preliminary ideas of my treatife on metallick fubftances (in this work.) The analogy between this ftone and metals has been eftablifhed by the experiments of Bergmann and of Mr. Lavoifier. . This ftone, when rather ftrongly heated, exhibits a bluifh light in the dark. To form thefe kinds of phofphori, the fpar is pulverized, the powder is kneaded up with mucilage of gum tragacanth, and the pafte is formed into pieces as thin as the blade of a knife. Thefe pieces are afterwards dried, and ftrong- ly calcined by placing them! in the mid ft of the coals of a fur- riace; they are afterwards cleared by blowing on them with the bellows. In this ftate, if they be expofed to the light for a few minutes, and afterwards carried into a dark place, they Shine like glowing coals. Thefe pieces Shine even under water ; but they gradually become deprived of this property, which how- ever may be reftored again by a fecond heating.—See De Four- croy. Ponderous fpar is eafily divided into plates by the Slightest blow ; and the moft ufual form which it aifeas is that of an hexahedral prifm, very flat, and terminated by a dihedral Sum- mit. Ponderous Spar has been found at the diftance qS one league Srom Clermont d'Auvergne, in the Sorm oS hexahedral prifms terminated by a tetrahedral or dihedral pyramid. I have Seen cryftals of two inches in diameter. It frequently happens that the Sorm of thefe cryftals is not very determinate ; but all the ftones of the nature of thefe ex- hibit a confufed affemblage of feveral plates applied one upon' another, and capable of being feparated by a very flight blow. Ponderous fpar is infoluble in water ; and upon this property is founded the virtue poffeffed by the muriate of barytes, to man- ifest the flighted portions of fulphurick acid in any combina- tion which contains it. ^ Barytes adheres more ftrongly to acids than the alkalis them- felves do ; and when the carbonates oS alkalis precipitate it, the e*fea takes place in the way of double affinity. So© Carbonatet Nitrate and Muftate of Barytes, SPECIES n. Carbonate oS Baryte s. This combination has the Specifick gravity of 3.773* One hundred parts contain twenty-eight water, feven acid^ fixty-five pure earth. The Sulphurick, nitrick, arid other acids attack it with effer- vefeence. ._..,, Although the carbonick acid poffeffes the ftrongeft affinity with this earth, it is very Seldom found in combination with it : and I am acquainted with its exiftence only on the authority of Mr. Kirwan, who affirms that Dr. Withering prefented him with a fpecimen from Alfton Moor, in Cumberland ; which re- fembles aliim, with the difference that its texture is Striated, and its Specifick gravity is 4.331.* , Mr. Sage analySed this ftone, which was preSented to him by Mr. Greville. See the Journal de Phyfique for April 1788. species ui. Nitrate of Barytes.' The nitrick acid diffolves pure barytes, and forms a fait which cryftallizes Sometimes in large hexagonal cryftals, and frequently in fmall irregular cryftals. The nitrate is decompofed by fire and, affords oxigene. The pure alkalis do not diSengage the barytes, but the alka- line carbonates precipitate it by double affinity. The Sulphurick and fluorick acids Seize this earth from the nitrick acid. It his not yet been found native. species IV. Muriate of Barytes. This Salt is capable of affuming a form considerably refem- bling that of fpar in tables or plates. It exhibits, with the e.irths, acids, and alkali, phenomena nearly fimilar to thofe of the nitrate of barytes. ^ It forms one of the moft interefting re-agents to afcertain the exiftence of the fmalleft particle of fulphurick fait in any * J>. is plentifully found in England, in the lead mine of Anglezark, near Chorley in Lmcafliire.. See the Manchester Memoirs, vol. iii. p. S'A- T. Epfom Soft. 201 water ; becaufe by the fudden exchange of principles, the refult is ponderous Spar, which immediately Sails down. It has not yet been Sound in a native ftate. genus nr. Earthy Salts with Bafis oS Magnefia. TheSe Salts were not well known before the time in which* the celebrated Black proved that they ought not to be confound- ed with calcareous Salts. They may be diftinguiffied from thefe by the bitter tafte which almoft all of them poffefs. They are in general very foluble in water. Lime-water pre- cipitates them, as does likewife ammoniack, or the volatile SfECIES r. Sulphate of Magnefia, Epfom Salt. This Salt is frequently met with ; it exifts in feveral mineral tvaters, Such as thofe of Epfom, of Sedliz, &c. It was at firft distinguished by the name oS the Springs which produced it ; and it is Still known by the name oS the bitter cathartick Salt, on account of its tafte and virtues. *i,Tfhi!rUl^hate0/magnefia* in comme**ce, comes either from the fait Springs of Lorraine, from which this fait is extraaed with a mixture of fulphur ; or otherwife from the fait works in the environs of Narbonne, where it is extraaed from the moth- er waters which contain it abundantly. r„Xhe f^Phate of magnefia, in commerce, has the form of final! hlky needles, very white. It does not efflorefee in the air which diftinguifhes it from the fulphate of foda. ' The cryftals of the pure fulphate of magnefia are quadranjru- larpnSms, terminated by pyramids of an equal number of fides rhe Sulphate of magnefia prepared in our fait works is fold at from thirty to forty livres the quintal j it containsin the pound three Sixteenths oS Sulphate oS Soda, two Sixteenths mu nate oS magnefia, one Sixteenth muriate oS Soda, fix Sixteenths true Sulphate oS magnefia: the reft confifts oS falts with bafis of lime. The fulphate of Magnefia, when expofed to the fire, liquefies and lofes half its weight. The remainder is dry, and requires a Strong fire to fuSe it. 4U"« Water diffolves its own weight of this fait, at the temperature •">! 60 degrees of Fahrenheit's thermometer. a d 2...R 202? Carbonate' of M'dgnefta. One hundred parts oS this Salt contain twerfty-foirr parts acid, nineteen earth, and fifty-Seven water. It exifts in all the waters in the environs of Montpellier. Sometimes it is found effloreScent upon Schifti, from which it may be colfeaed. I have found it upon a mountain in Rou- ergue, in a quantity Sufficiently great to be colfeaed to advan- tage : birds of paffage devour it greedily; This fait is ufed in preference to others as a purgative. SPECIES IT; ICitrate of MagnefTa. ,The celebrated Bergmann, who has combined magnefia with the various acids, obServes that the nitrick acid forms with it a fait capable of affording, by proper evaporation, prifmatick, quadrangular, truncated cryftals. The Same chemift adds, that this Salt is deliqueScent. Mr. Dijonval affirms, that he obtain- ed cryftals that were not deliqueScent ; and accident has afford- ed me a Salt of this kind in mother water of nitre concentrated to the 45th degree of the areometer. Its form was that of priSms with Sour fides, very much flattened, very thick, and' very. Short. This Salt decompoSes the muriates j alkalis- precipitate its magnefia, as does likewife lime. SPECIES III. Muriate of Magnefia: The muriate of magnefia exifts in the mother water of our fait works ; its tafte is very bitter. According to Bergmann, it forms a fait in fmall needles, fo deliquefcent that it cannot be obtained but by ftrongly concen- trating the folution, and afterwards expofing it to intenfe cold; Lime-water, barytes, and the alkalis precipitate the magnefia ; it may likewiSe be Separated by means oS fire. SPECIES IV. Carbonate of Magnefia. Though magnefia has the greateft affinity with the carbon- ick acid, I do not think that nature has ever exhibited this com- bination. It is obtained by precipitating the magnefia from- Aluminous Salts. 2C3 'Epfom'fait, by means of the carbonates of alkali; and in this -State it is called efferveScent magnefia, or magnefia, not cal- cined. The carbonate oS magnefia contains in the quintal thirty parts acid, Sorty-eight earth, and twenty-two water.—See Kirwan and Bergmann. Magnefia fticks to the tongue; and affumes, in drying, a certain transparency, which it preferves until it has loft all ks water, which is not. eafily driven off. Fire carries off the water and the acid; and in this ftate the •refidue is called callcined magnefia, The carbonate of magnefia is foluble in water in the propor- tion of feveral grains-in an ounce of the fluid. But we are indebted to Mr. Butini for a very lingular obfer- vation—that cold diffolves more than hot water, and that the magnefia may be precipitated by heating the water which holds it in Solution. Hence it ariSes that waters loaded with magne- fia become white and turbid by ebullition. The celebrated Bergmann had advanced that the carbonate of magnefia is cryftallizable. Mr. Butini, by concentrating a Sat- urated Solution of this fait with a gentle heat, obtained groups *of cryftals, which, when examined by the microfeope, appeared to be hexagonal truncated prifms. I have obtained Similar ihow-like flocks by precipitating magnefia by the addition of an alkali, drop by drop. The carbonate of magnefia is ufed in medicine as a purgative. The calcined magnefia ought to be preferred as an abforbent. -.GENUS IV. Earthy Salts with Bafe of Alumine. The fubftance which in the arts is known by the name of Clay, ^s a natural mixture of feveral earths. Alumine, or pure clay, is capable of combining with the greateft part. of the known acids 9 but the moft common of .thefe Salts is aluip. species 1. Sulphate of Alumine, Alum. Though alum be very commonly met with, yet the combi- nation of principles which conftitute it is not effeaed without confiderable difficulty. 204 Manufacture of Alum. Pure clay upon which the fulphurick acid is digefted, is dif- folved with difficulty : and it is by no means eaSy to bring this Combination to regular cryftals. The ufual produa is a faltj, which appears to be formed by Scales applied one upon the other. The moft ordinary proceSs to diffolve alumine by means of an acid, confifts in calcining the clay, impregnating it with the acid, and facilitating its aaion by an hea.t of 50 or 60 degrees of Reaumur. But a Simpler method, which I have ufed in my manufaaory of alum, confifts in prefenting the acid in vapours, and under the dry form, to the clay properly prepared. For. this purpofe I calcine my clays, and reduce them into Smalt pieces, which I fpread over the floor of my leaden chambers. The fulphurick acid, which is formed by the combuftion of a mixture of fulphur and faltpetre, expands itfelf in the cavities of thefe chambers and exifts for a certain time in the vaporous^ form. In this form it has a ftronger aaion than when it has been weakened by the mixture of a quantity of water more or lefs confiderable : fo that it feizes the earths, combines with them, caufes them to increafe in bulk by the efHorefcence which takes place, and at the end of feveral days the whole furface ex- pofed to the vapour is converted into alum. Care is taken to ftir thefe earths from time to time, that they may Succeffively prefent all their furfaces to the aaion of the acid. But whatever procefs may be ufed to combine the acid with clay, it is neceffary to expofe the aluminized earths to the air during a greater or lefs fpace of time, in order that the combi- nation may be more accurate, and the Saturation more com- plete. Moft of the alum in commerce is. afforded by ores which are dug out of the earth for this purpofe. We may reduce all the operations of this manufaaure to three or four ; the decompofi- tion of the ore, the lixiviation of the ore, the evaporation of thefe lixiviums, and the cryftallization of the alum. 1. The decompofition of the mineral is effeaed either in the open air without affiftance. or elfe by means of fire. When the mineral is left to decompofe Spontaneously, nothing more is done than to diSpoSe the ftone which contains the prin- ciples oS alum in Strata or layers. The pyrites becomes heated ; acid is formed, which diffolves the clay ; and the Salt arifing from this combination exhibits itSelfby the eSfloreScence of the pre. The decompofition may be accelerated by watering the heap of pyrites ; but the operation may be ftill more abridged by the affiltance of fire.—The method of applying the heat varies prodigioufly. On this head Bergmann may be confulted ; but h\ general it may be obferved that it ought not to be either too Manufacture of Alum. 205 ftrong or too weak. In the firft cafe it volatilizes the fulphur, and in the fecond it retards the operation. The ore of alum is fometimes impregnated with a fufficient quantity oS bitumen to maintain the combuftion.—See my Me- moir on the Alum Ore oSVabrais, 1785. 2. When the ore has effloreSced into alum, the Salt is extraaed by lixiviation. For this purpoSe the fame water is paffed over fev- eral heaps of aluminous earth, in order to Saturate it. The wa- ter which is firft paffed over the earth diffolves in preference the .vitriol, which is more or leSs abundant; and this fait may b* feparated Srom the alum by a previous cold-wafhing. 3. Th^ lixivium, or Saline Solution, is carried into leaden cal- drons, where the fluid is properly concentrated. In this part pf the proceSs it is that an accurate Saturation of the alum is ef- feaed when the acid is in excels j and Sor this purpoSe alkalis are added, which Serve likewife Angularly to facilitate the cryf- tallization. The celebrated Bergmann has propofed to boil clay with the folution, to Saturate the exceSs of acid. This procefs feems in every point of view to be advantageous ; but it appears to me to be impraaicable, becaufe the Superabundant acid cannot be made to combine with the clay, but by a very long ebullition, and I have obServed that, by afterwards evaporating the fluid to caufe it to cryftallize, this clay falls down and oppofes the cryf- tallization. I have varied the procefs in a variety of ways, with- out obtaining the fuccefs which its celebrated author prediaed. There are methods of greater or lefs accuracy to judge of the degree of concentration to which it is proper fo carry the lixiv- ium, in order to obtain a good cryftallization ; fuch are, the im- merfion of an egg in the liquid, the effuGon of fome • drops in the lixivium on a plate, &c. Mr. De Morveau has propofed a metallick hygrometer ; but this inftrument cannot be confidered as very accurate, becauSe its immerfion in the liquid is propor- tional to the heat of the fluid in which it is plunged. 4. The lixivium is then conveyed into coolers, where it cryf- tallizes by mere reSrigeration. The pyramids of alum are con- ftantly turned towards the bottom of the veffel, more efpecially thofe which fix themfelves to the fticks which are put into the liquor to multiply the furfaces. Alum affeas the form of two tetrahedral pyramids, applied to each other bafe to bafe. Sometimes the angles are trunca- ted, and thefe truncatures take place moft frequently when the lixivium is flightly to acid. This fait requires fifteen times its weight of water to diffolve jt, at the temperature of fixty degrees of Fahrenheit, according to Kirwan. ,2©5 Carbonate e>f Alumine, its tafte is ftyptick ; it lofes its water of cryftallization by heat; at the fame time that it fwells up, and is converted into ^ -light and white fubftance, called burned or calcined alum. •If it be urged by a violent degree of heat, it lofes part of its acid, and becomes taftelefs. The refidue is no longer fufcepti- ble of cryftallization, and precipitates in the form of a very fine adhefive powder, in proportion as the water is diSperSed by evap- oration. Alumine is precipitated Srom this Solution by magnefia, ba- ■rytes, and the alkalis: theSe laft diffolve the precipitate in propor- tion as it is formed, if they be added in exceSs. Alum is a very valuable material in the arts. It is the foul of the art-of dying, and Serves as the mordant to all colours. *It is ufed to prepare leather, to impregnate paper and cloths in- tended to be printed. It is added to tallow, to render it harder; ■it enters into the preparation of a glue for the deftruaion of ver. min ', it is employed in England, and elfewhere, to give white-« nefs, and additional weight to bread. When fuSed with Salt- petre of the firft boiling, it Sorms a very white cryftal mineral. The printers rub their balls with calcined alum to cauSe them to take the ink. Surgeons employ it to corrode fungous or -proud flefh. SPECIES it. ■Carbonate of Alumine. The argillaceous earth precipitated Srom the Solution of alum, by the carbonates of alkalis, combines with their acid ; but this fait is very rarely found in nature. I know only of the observa- tion of Schreber which aScertains its exiftence. This naturalift afferted that the earth known by the name of Lac Lunae is a true jcarbonate of alumine. Although alumine be foluble in the other acids, we are very little acquainted with its combinations. It is only known that the nitrick acid diffolves it, that the folution is aftringent, and •that it may be obtained in Small ftyptick and deliqueScent crys- tals. The muriatick acid has a more evident aaion upon alumine. This muriate is gelatinous and deliqueScent. TheSe Salts have not been applied to any ufe, and they are no where Sound in nature. Earthy Mixtures: »? GENUS V. Earthy Salts with Bafe of Silex. &lex is of all the known earths that which combines the moft difficultly with acids. We are even acquainted with no other acid than the fluorick Which exerts an evident aaion upon it. It rifes with it, and holds it in folution until it abandons it to unite with water. Some experiments of Mr. Achard gave reafon to think that the carbonick acid diffolved filex ; but the Parifian chemift did' not obtain the refults announced by the chemift' of Berlin; M. Jbe Morveau Seems to have proved that iron and the carbonick acid were neceffary to Sorm rock cryftals ; but tins acid does not remain united and combined with the earth ; So that we have not hitherto arrived at any proof of its diffolving virtue. class ir. Concerning the Combination and Mixture of Primitive Earths, or Earthy Mixtures. The pure and fimple earths, Such as we have deScribed themr are rarely Sound on the SurSace of the globe. They are con- flantlv mixed wirh each other, and form maffes oS greater or leSs magnitude, and various hardneSs, according to the nature of the earths, their ftate of divifion, and the charaaer of the for- eign fubftances which are combined with them, fuch as iron, bitumens, &c. It may be eafily underftood that the number of compositions which can refult from the mixture of five primitive earths, would be infinite, if we were to pay attention to Suchflight va- rieties as depend on the proportions oS the mixture : but I fliall not conGder any mixtures as conftituting Species truly diftina, except Such as differ in the identity of their conftituent princi- ples. The flight differences in the proportions of thefe princi- ples mav indeed occafion modifications in" the form, the hard- nefs, the colour, &c. But thefe can never conftitute more than varieties. We Shall naturally deduce the genus from the ftone or earth which predominates in any mixture, and appears to communi- cate its own charaaer to the total mafs. In this manner we Snail claSs among the calcareous mixtures Such ftones as exhibit to our observation the properties of lime-ftone to fuch a degree, that they would be taken to be purely calcareous if the chemical analyfis did not prove the exiftence of other principles. 20 8 Calcareous Mixture?, The genus ought not in ftrianefs to be taken and deduced from the earthy principles which predominates ; for the charac- ter of the whole mafs or of the mixture, is very frequently given by an earth which does not form the moft abundant principle ; as we obServe more eSpecially in magnefian earths, where the filex- predominates over the magnefia. GENUS i. Calcareous Mixtures. According to the principles we have laid down, we muft re- fer to this place thoSe ftony mixtures in which the properties of lime-ftone predominate. species f. j Lime-ftone and Magnefia.- i This mixtitre is very common ; almoft all the calcareous ftones contain magnefia. Mr. Bayert has deScribed a variety in the Journal de Phyficfue, t. xiii. which contain in the hundred parts Seventy-five carbonate of lime, twelve magnefia, and thir- teen iron, it is the earth of Crenizwald. Mr. Woulfe has de- Scribed another Variety in the PhiloSophical trarrfaaions for 177c* It afforded fixty parts carbonate of lime, thirty-five carbonate of magnefia, and three of iron. The analyfis which I have marie of feveral lime-Stones in our province, conftantly afforded magnefix. species it. Lime-ftone and Barytes. Mr. Kirwan has informed us that this Species is found in* Derbyshire, in the Sorm of a ftone, and likewife in the earthy ftate. It is of a grey colour, and harder than ordinary lime- Stones. species hi. Carbonate of Lime and Alumine. This mixture is frequently met with. It is commonly known by the name of Marie. Tire proportions of the two conftituent principles are infinitely various. It is upon this proportion that the diftinaion of fat marles and lean marles depends, and dif- pofes them to ferve as manure for earths of different kinds. The marles are almoft always coloured by iron. Earthy Mixtures* 2bQ They appear to arife from the decompofition of the natural mixtures of chalk and clay, and contain more or lefs of filex ; but the analyfis which I made fix years ago of all the marles I could procure, convinced me that they were often nothing more than a mixture of clay and chalk. I have likewife found mag- nefia in marles, fometimes in the quantity of feventeen parts in the hundred ; but, in general, they may be confidered as formed effentially by the two earths here mentioned. Alumine is found likewife mixed with carbonate of lime in marbles. Mr. Bayen has proved this in the fecond volume of the Journal de Phyfique : and I have confirmed the truth of his refults by the analyfis of feveral marbles of our province. It is ev«n upon this principle that we may account for the greafy polifh which feme of them take. The very evident difference which may be eftablifhed between the mixtures which form marie and marble, is that the firft is the immediate produa of a decompofition principally effeaed by the alterations of the iron it contains ; whereas, the fecond is produced by a purely mechanical mixture of two principles al- ready formed, which being pounded, and ground as it were to- gether, form a compaa, hard, clofe affemblage, fufceptible of the moft beautiful polifh. Species iv. Lime-ftone and Silex. This fpecies is not common. It is known under the name of StellatedSpar, SternSchoerloSthe Germans. It is opake, oS a radi- ated texture or Sorm. Mr. Fitchel Sound it in lime-ftone on the Carpathian mountains. It effervefces with acids ; and, accord- ing to Mr. Bindheim, one hundred parts of this ftone contain fixty-fix carbonate of lime, thirty filex, and three iron.— See Kirwan. The mixture of the pulverulent Temains of the primitive rocks tranfported into olt country by the rivers which rife in the Alps and the Cevennes, together with our own calcareous frag- ments, frequently form beds of a ftone of this nature. The on- ly difference between them is, that our mixtures exhibit a con- fufed affemblage oS all the principles which belong to the prim- itive rocks, Such as clay, filex and others. . SPLCIES v. Lir.ie-ftoae and Bitumen. This mixture is known by the name of Swine-ftone. It a* bounds in the dioceSes cf Alais «r.d Uzes : I have Seen the saL 2...C 2io Earthy Mixtures. caseous rock impregnated with bitumen in an extent of more" than three leagues diameter. It is even fo abundant in fome parts, that it diftils through the clefts of the rocks, and forms ilalaaitous bitumen, which the peafants colfea to mark their Sheep, or to greaSe their cart-wheels. The heat of our fummer fometimes foftens it to Such a degree, that it flows into the roads, where it adheres to and impedes the motion of the fledges and other carriages. In fome places the ftone is fo well impregnated with bitumen, that it may be wrought; but the blow of a hammer cauSes it to emit an abominable fmell. Mr. D'Avej'an, bifhop oS Alais, having uSed this ftone to pave the apartments of his palace, the friaion and heat difengaged fo unpleafant a Smell, that his Suc- ceffors were obliged to Substitute a ftone of another kind in its flead. N Mr. De la Peyroufe found this ftone in large maffes near Saint Beal in Comminge, at L'Eftagneau, and the mill of Langlade. species vi. Lime-Stone and Iron. Iron is almoft always a conftituent part of lime-ftone ; but it fometimes exifts in fuch a proportion, that thefe mixtures con- ftitute iron ores. Mr. Kirwan defcribes two of this nature; one of which contains twenty-five pounds of iron in the quintal, and the other ten. Mr. Rinmann has defcribed ftalaaites which afford Iron, in the proportion of from twenty-feven to twenty pounds in the quintal. Calcareous iron ores are wrought in many parts of our prov- ince. I have myfelf obtained forty-four pounds of iron in the quintal, from a calcareous ftone which abounds on the moun- tain of Frontignan. It is common to find, in our calcareous mountains, hematites rich in iron, whofe bafe is calcareous ; we find likewife fpecies of ludus of the fame genus, and fometimes even tufa, whofe formation arifes from waters loaded with iron and lime. • The fpathofe iron ores are of the fame clafs as thofe we have j uft treated of. genus ir. Barytick Mixtures. Thefe mixtures are very rare, becaufe the ftone itfelf is Scarce* We fliall mention only two fpecies. Earthy Mixtures, 2.11 SPECIES I. Sulphate of Barytes, Petroleum, Gypfum, Alum, and Silex.—Bergmanni • Sciagr. f. 90 ; Kirwan Min. p. 60. The name of Hepatis Stone (Lapis Hepaticus) has been given , to this mixture. The colour varies much: its texture is uniform, lamellated, fealy, or fparry. It takes the polifh of alabafter. It forms a kind of plafter by calcination, and emits a Strong and fetid fmell by friction. One hundred parts of this ftone contain thirty-three barytes, thirty-eight filex, feventeen alum, feven gypSum, and five petro- leum. SPECIES 11. Carbonate of Barytes, Iron and Silex. Mr. Kirwan has mentioned this ftone on the authority of Mr. Bindheim. It is inSoluble in acids, and oS a Sparry texture ; but he is tempted to confider it as a Sulphate oS barytes, in con- Sequence oS the property obServed by Mr. Bindheim, that it be- comes Soluble in acids, aSter having been calcined with oil. GENUS JIJ. 1 Magnefian Mixtures. All the Species compriSed in this genus poffeSs charaaers Suf- ficiently ftriking, and eafily known. They are in general greaSy and SoSt to the touch ; they may be cut with a kniSe, turned in a lathe, and converted into any form atpleaSure. They take a tolerably good polifh. Some oS them are diSpoSed into fibres; and thefe fibres poffeSs Sor the moft part, a remarkable degree of flexibility. They flick to the tongue like clays ; but do not, like them, foften in the water. species 1. Pure Magnefia, Silex, and Alumine. species 11. Carbonate of Magnefia, Siiex, and Alumine. The mixture of thefe three earthy principles forms talcs, fteatites, pot-ftones, or lapkies ollares. -1 i Earthy Mixtures. The difference which analyfis Shews between thefe two fpe- cies, is almoft entirely confined to the proportions oS their con- ftituent principles. This circumftance might appear Sufficient to authorize us in considering them only as varieties oS each other. But as the magnefia is pure in the talc, and in the State of carbonates in the fteatites, we Shall confider them as different Species. i. Pure magnefia, mixed with near twice its weight of filex, and leSs than its weight oS alumine, Sorms talc. It is.of a white, grey, yellow, or greeniffi colour ; foft and Soapy to the touch, compofed of transparent lamina? placed upon each other. TheSe lamina; are more tender than thoSe of mica ; they lock together, and are ufually divided into rhombi, and may be crush- ed or feratched with the nail. Its fpecifick gravity is 2.729. Fire renders it more brittle and white ; but it is infufible by the blow-pipe, and can Scarcely be SuSed by the addition oS alkali. The borate of foda, and the phofphate of urine, fufe it with a flight effervefcence. Mufcovy talc is compofed of large elaftick, flexible, and trans- parent leaves. Plates of talc have been raifed in the quarries of Vitim in Siberia which were eight feet fquare. 2. Steatites is ufually of a. greeniffi white: it may be eafily cut with a knife; and the dull which is produced by Scraping it does not readily mix with water. Its fpecifick gravity is about 2.433. It is infufible alone, hardens in the fire, and becomes white. The borate of foda facilitates its fufion ; but Soda, and the phof- phates of urine, do not perfeaiy diffolve it. According to the analyfis of Bergmann, one hundred parts of Steatites contain eighty filex, feventeen magnefia, in the ftate of carbonate, two alumine, and one iron. Steatites is fometimes found in maffes of indeterminate fig- ure, and fometimes cryftallized, fuch as that which Mr. Ger- hard found at Raichewtein, in Silefia. Chem. Ann. 1785.— And Mr. Rome de Lifle poffeffes cryftals in hexagonal laminae refembling the leaves of mica. The white fteatites of Briancon is compofed of irregular, fri- able, and femi-tranfparent leaves. It often inclofes cryftals of Steatites, of a white or greeniffi colour, which have the form of tetrahedral prifms. The fteatites oS Corfica appears to be formed by fibres placed befide each other. It has a greenifh colour, and no perceptible degree of flexibility. The fteatites of Bareith is grey, cOmpaa and folid. Earthy Mixtures. 213 That of Queen Charlotte's Bay in New-Zealand is ftriated, -reen, femi-tranfparent, and fufficiently hard to give fire with die fteel. 3. The foap-ftone of China is a fteatite, often ftriated; but it is not more unauous than thole we have already mentioned. The fteatites of Briancon forms the bafis of the vegetable red. 4. The lapis ollaris, or pot-ftone, is only a variety of the fteatites. It does not appear to me to differ from it excepting in being harder. Its colour is ufually greyiffi ; but it is fometimes blackened by bitumen. Mr. Gerhard has obferved that the lapis ollaris of Sweden effervefces with acids, and contains calcareous earth; But this mixture is peculiar to it. Thofe of Saxony, Silefia, and Corfica do not contain it. The lapis ollaris may be wrought with the greateft facility. In the country of the Grifons, in Corfica, and elfewhere, it is turned, and formed into veffels which refill the fire, and have not the inconvenience of our glazed pottery ; it is from thefe ufes that it has obtained the name of Lapis Oilaris, Pot Stone, &c. species nr. Ture Magnefia combined with fomewhat mere than its weight of Silex, one third of Alumine, near one third of Water, and more or ids of Iron. This mixture forms the ferpentine. It has a great analogy with the preceding fubftances, but is diftinguifhed from them by a more evident degree of hardnefs ; by the property of acquiring a more beautiful polifh ; and by a quantity of iron fufficiently confiderable to afford it a peculiar charaaer. The ferpentine is whitiffi, greenifh, bluifli, or blackiffi ; fre- quently marked with black Spots, and Sometimes interieaed with bands oS various colours. Some Serpentines are even trans- parent. The Royal cabinet of Mines poffefs a fpecimen whofe ground is grey, and interfperled with reddifh, femi-tranfparent, and chatoyanc fpots. Serpentine varies likewife in its texture. It is compaa, granulated, fcaly, lamellated, or fibrous. It takes the moft beautiful polifh. The iron it contains is Sometimes obedient to the magnet. Its Specifick gravity is Srom 2.4 to 2.65. It melts in a violent heat ; but a leSs degree oS fire hardens it. Mr. Bayen, who has analyfed the ferpentine, found it to con- tain, in the hundred parts, forty-one filex, thirly-three magnefia, twenty alurr.ine, three iron, and alf.*> water. £14 Earthy Mixtures, Mr. Kirwan has obferved, that the ferpentine of Corfica, con* tained more alumine, and lefs filex. Mr. De Joubert poffeffes a Species of ferpentine which exhib- its Square plates on its Surface. Mr. Dorthes has obferved feveral varieties of the ferpentines. on our Mediterranean coafts, and in the river of Herault, which receives them from the mountains of the Cevennes. species IV. Carbonate of Magnefia j Silex, Lime, Alumine, and Iron. This combination exhibits feveral varieties, which are known under the name of Afbeftos, Mountain Cork. Their texture Serves to diftinguifh them ; but the chemical analyfis confounds them together, and does not permit us to allow any other dif- tinaion than that of varieties. VARIETY I. Afbeftos. This ftone is ufually greeniffi ; its texture is Sometimes fi-< brous and compaa, and Sometimes membranaceous. Near Bagneres de Bigorre, in the mountains of the environs of Baffere, Meffrs. Dolomieu and La Peroufe found cryftals of afbeftos in rhomboidal parallelopipeds. Afbeftos is rough to the touch, brittle and rugged. Its fpecif- ick gravity is from 2.5 to 2.8. Fire renders it whiter and more brittle. It is infufible by the blow-pipe, according to Kirwan ; but the abbe Mongez affirms that afbeftos and amianthus are fufible, and form an opake glo- bule, which becomes bluifh. It is difficultly foluble with fo- da ; but more eafily with borate of loda and the phofphates of urine. According to Bergmann, the afbeftos contains in the quintal from fifty-three to feventy-four filex,about Sixteen parts magnefia, from twelve to twenty-eight carbonate of lime, from two to fix alumine, and from one to two iron. VARIETY 11. Mountain Cork. This name has been given on account of a flight refemblance of this fubftance to cork. This ltone is very light, membrana- ceous, flexible, and uSually of a yellcwcolour. 'It may be more Earthy Mixtures. 2t£ feafily torn than broken. „ The diocefe of Alais affords very fine Specimens. Among a very great number of ftones of this nature, fubjea- ed to analyfis by the celebrated Bergmann, the filiceous earth was always found predominant; and after that the magnefian, which was never lefs than twelve parts in the hundred, nor more than twenty-eight. species v. Carbonate of Magnefia and Lime, Sulphate of Barytes, Alumine, and Iron. This combination forms amianthus. It is compofed of long flexible fibres, parallel to each other, and very foft to the touch. They are fometimes very white, but often yellowiffi. The filaments may be Separated and detached Srom each other; and may be even twifted in any direaion without danger of break- ing them. Their flexibility is fo wonderful, that they may be formed into cloth. The ancients constructed cloths of this kind, in which they burned the bodies of the dead ; and by this means the afhes were colfeaed without mixture of thofe of the fuel. Mr. Dorthes found amianthus in tufts upon calcareous ftones thrown up by the fea, on which it was fixed with plants, coral- lines, gorgonia, &c. He believes, with reaSon, that this amian- thus did not originate upon the ftones, but that it was depofited by the water. He found likewife, on the coaft, balls of the amianthus of two or three inches diameter imitating aegagropilesy and formed by the intertwining of the threads of amianthus ; and covered with a white tophofe fubftance, of the nature of that which covers the gorgonia, and is the work of a fpecies of fea animalcule. The fibres of amianthus are of various lengths. I have re- ceived fpecimens from Corfica, whofe filaments were very flex- ible, and eight inches long. That from the Pyrenean mountains has fhorter fibres. Bergmann analyfed an amianthus from the vicinity of Taren- to, of which 100 parts afforded 64 filex, 18.6 magnefia, 6.0 lime, d fulphate of barytes, 3.3 alumine, 1.2 iron. GENUS IV. Aluminous Mixtures. Argillaceous or aluminous ftones are common enouTh, They are Seldom poffeffed of more than a moderate degree of 216 Earthy'Mixtures. Pottery. hardnefs, and are divisible in.water. But the mixture of their principles is in fome inftancik fo intimate, that they poffeSs a' very Strong degree of confiftcneV \ species "*. Alumine, Silex, Carbonate of Lime, and more briefs of Iron. We may here place all the varieties of clay. Chemical anal- yfis exhibits, conftantly enough, the principles whofe mixture forms this fpecies ; but the proportions among thefe conftituent principles vary fo much, that the varieties of clay are almoft infi- nite. Independent of the principles above enumerated, we fometimes find lime combined with clay, and Sometimes even magnefia ; and it will be eafy to form various fpecies, in pro- portion as the analyfis of thefe earths fhall become more perfea. The argillaceous mixtures of "which we propofe at prefent to fpeak, are charaaerized by the following properties :—:They ad- here ftrongly to the tongue, become dry, hard, and Shrink in the fire; are divided, arid form a pafte, with water, iri which ftate they may be eafily moulded and turned, &c. The clays iri which the filiceous principle is moft abundant are the drieft, adhere lefs to the tongue, are lefs completely diffufed in water", and crack lefs when dried by the heat of the fire or the fun. Moll clays contain iron ; and this metal is ufually the prin- ciple of their colour. From the brownifh clay, in which iron is almoft in the native ftate, to the deepeft red, all the various Shades are owing to the feveral degrees of alteration in this metal. Thefe various changes are effeaed either at the furface of the globe by the immediate aaion of the air, which calcines the iron, or elfe in the bowels of the earth : in which laft cafe, the effeas arife from the decompofition of water and of the py- rites. We may trace this beautiful work of nature in feveral pyritaceous ftrata in our province ; and ori this Subjea, refer- ence may be had to my Memoir upori the Brown Red (Brun Rouge), printed by Didot by order of the province. We Shall direa our attention leSs to the Several varieties of clay than to the ufes to which they are applied. The firft of thefe ufes is to form the bafis of pottery. Several fpecies of pottery may be obServed, which neverthe- less differ Srom each other only in the degree of finenefs oS the earths made uSe of, and the care that has been taken in per- forming the various manipulations which they undergo. r. The moft common pottery is made with any kind of clay* Indifcriminately, which is mixed with fand, to render it more porous, and by this means more adapted to Support the heat. fcarthy Mixtures. Pottery. 2 ij Thefe veffels would be penetrable by water, if they were not Covered with a glaze. The glazes of pottery are ufually made either with the Sul- phureous lead ore called Alquinfoux, and in England, Potters' Lead Ore, or with the yellow copper ore. For this purpofe, thefe fubftances are reduced to powder, mixed with water, and the veffel, previoufly dried by a flight baking, is dipped in the mixture. The porous veffel abforbs the water, while its furface becomes covered with the pounded ore. The veffel is then car- ried to the furnace, and baked by a heat which vitrifies the ore upon its furSace : and it is this metallick glaSs which Sorms the glaze oS the potters, and is yellow of green, according to the met- al made uSe oS. TheSe glazes are all dangerous j becaufe they are foluble in fats, oils, acids, &c. The attention of intelligent manufaaurers has been long di- reaed to the methods of fubftituting in the place of thefe glazes, others which are not attended with the fame danger. We might after the manner of the Engliffi, vitrify the furSace of our pottery by means oS Sea Salt thrown into the fire-place when the Surnace is at a white heat ; but this method is im- praaicable in moft of our manufaaories, becauSe our fires are riot Sufficiently Strong. I have tried various methods to glaze pottery ; and two a- mong them have Succeeded well enough to juftiSy my publishing them. The firft confifts in mixing the earth oSMurivel iri wa- ter, and dipping the pottery therein : this done, they are Suffer- ed to dry : after which they are plunged into a fecond water, in which levigated green glafs is mixed. * This covering of vit- reous powder fufes with the clay of M'urivel ; and th'e refult is a very fmooth, very white, and very cheap glazing. The fecond method confifts in immerfing the dried pottery into a Strong folution of fea Salt, and aSterwards baking them. The trial which 1 have made in my Surnaces gives me reafon to expea that this method may be ufed in large works. I have likewiSe obtained a very black glazing, by expofing pottery ftrongly heated to the fumes of fea-coal. I have coated feveral veffels in this manner, by throwing a large quantitv of coal in powder into a furnace wherein the pottery was ignited to whitenefs. The effea is ftill more complete when the chim- neys or tubes of afperaticn of the furnace are at that moment Clofed, and kept So Sor Some minutes. I have given an account oS all thefe circumflances, and many others, in a work preSented to the Royal Society of Sciences of Montpcliier ; in which I hr.ve proved, from the re Suits of mv 2...D 218 Earthy Mixtures. Pottery. experiments in the large way, that the belt mixture of our owrt earths is capable of affording us the moft beautiful and fineffc pottery of every kind. 2. Fayence.* This does not differ from the pottery we have here Spoken of, except in the degree of SineneSs of the earths ufed for its bafis, and the nature of its covering or glaze. The glazing of fayence is nothing elfe, as is well known, but glaSs rendered opake by means of the oxide of tin. It is the glaSs called Enamel. To make the fine white enamel of the potters, one hundred pounds of lead, thirty of tin, ten of marine fait, and twelve of purified pot afh, are calcined together. This mixture, after calcination and fufion, produces a beautiful enamel, which is applied in the fame manner as the glaae before fpoken of. Bernard de Paliffy excelled in the art of fayencery ; and it is to him that we are indebted for our firft acquisitions in this manufaaure.f * Diftinguiflied by us by the name of Delft Ware. T. f I cannot refift my inclination to infert in this place a few circum- ftances of the life of this great but unfortunate man, who lived in the 15th' century. He was a native of the diocefs of Agen, and his firft employ- ment was that of furveyor or draftfman of plans : but his tafte for natu- ral hiftory led him to abandon this employment : and he travelled for inftruction over the whole kingdom, and Lower Germany. An acciden- tal circumftance threw into his hands a cup of enamelled pottery ; and, from that time his whole time and fortune were taken up in experiments on enamels. Nothing can be more interefting than the narrative which he himfelf ha9 given of his labours. He exhibits himfelf building and re- building his furnaces ; always on the eve of SucceSs ; worn out by labour and misfortune, the derifioa. of the pubiick ; the object of the angry re- monstrances of his wife ; and reduced to burn the funiture, and even the wood-work of his houfe, to keep his furnace going.- His workman preffes him for money ; he Strips himfelf, and gives him his clothes. But at length, by dint of indefatigable labour, conftancy, and genius, he arrived at the defircd degree of perfection ; which gained him the efteem and confideration of the greateft men of his age. He was the firft who form- ed a collection of natural hiftory at Paris, and even gave lectures on that fcience ; receiving half a crown from each of his auditors, under the ob- ligation of returning it fourfold if any thing he taught fhould prove falfe. The high reputation he acquired, ana the obligation under which his coun- trymen flood indebted to him, were not Sufficient to defend him from the persecutions of the League ; for Matthew De Launay, one of the greateft fanaticks, caufed him to be dragged to the Baftile at the age of ninety years. He fignalifed himfelf in- his prifon by acts of firmnefs and heroifm- Henry the Third vifitedhim, and reprefented his fituation in thefe words : *' My good man, if you cannot reconcile yourfelf to the matter of relig- ion, I fhall be compelled to leave you in the hands of my enemies."— Faliffy anfwered, " Sire, I was perfectly ready to Surrender my life for " the glory of GOD. If this action could have been accompanied with " any regret, certainly it muft have vanifhed after hearing the great King Earthy Mixtures. Porcelain. 2 TO 3. The fined pottery is known by the name of Porcelain ; it (ought to be white, transparent, and oS a Sine grain. The firft procelains were manufaaured in Japan and China. The celebrated Reaumur firft undertook a capital feries of experiments to imitate thefe potteries: but, deceived by the femi-tranfparence and vitreous apppearance of porcelain, he imagined it to be a Semi-vitrification, and attended only to the means of flopping the procefs of vitrification at a certain Stage of its effea, or of caufing it to become reverfed. He fucceed- ed in his undertaking, by filling bottles with fand and gypfum, and expofing them to a potter's furnace. I have likewife pro- duced the fame effea by a very different ptBcefs, though depen- dent on the fame theory. When I concentrate my oil of vitriol in the green glafs of our manufaaure, that part of the retort which is continually Struck by the rifing oil of vitriol becomes white, and lofes its tranfparence. This phenomenon constant- ly takes place, whenever the fire is raiSed Some what more than uSual. The retort preServes its form ; but all its alkali is ex- traaed, and there remains only the quartzofe principle of a beautiful white colour, fomewhat cracked like the procelain of Japan. As the decompofition commences at the interiour fur- face, which is immediately aaed on by the vapours, this furface is frequently rendered white, and diScoloured; while the exte- riour furSace remains perfeaiy vitreous, and exhibits a Striking contraft. For, when the interiour SurSace of the glaSs is in- fpeaed, it preSents a white covering applied againft a SurSace oS glaSs ; forming, by the union of both, a thickhefs no greater than that of which retorts are ufually made. Father Dentrecolles fent from China the fubStances uSed in the Sabrication of porcelain: they are known by the names oS Ka- olin and Petunce. Similar Subftances were Soon Sound in France; and our porcelain manufaaories, in a fhort time, equalled the moft beautiful produaions of this kind, and even exceeded them \n the beauty of defign and figure. The manufaaory of Seves " of France fay, J am compelled. This, fire, is a fituation to which nei- " ther yourfelf, nor thofe who force you to act contrary to your own dif- " poiition, can ever reduce me : becaufe I am prepared for death ; and " becaufe neither your whole people, nor your Majefty, poflefs the "power of forcing a fimple potter to bend his,knee before images."— Bernard de Palifly was the firft who affirmed that calcareous mountains are the remains of Shells. He has exhibited Such a degree of intelligence and Sagacity in all his writings, that he deferves to be placed among thofe great men who are an ornament to our nation. The very form of his works exhibits a proof of original genius. They confift of di- alogues between Theory and Practice. Practice is always the inftrudt- .or; and Theory is reprefcnted as a Scholar, proud of his own under-. ftandirg but indocile and ignorant. aae Earthy Mixtures. Mica. is at prefect, without contradiaion, the firft in the world. No- thing can equal the beauty oS its paintings, the regularity of de- fign, and the elegance oSform, which are given to the veSTels produced in this manuSaaory. Four principal operations may be diftinguifhed in the manu- faaure of porcelain.— i. The preparation, the mixture ofearths and the working of the pafte. 2. The firft baking, which forms the biScuit. 3. The application and fufion oS the glaze and covering. 4. The art oS painting, which demands a third baking, in order that the colours may be better combined, Sufed, and amalgamated with the glaze. I have mySelS made very beautiSul porcelain with the kaolin, which is found in veins in the granite of St. Jean de Gardon- enque, and the feld fpar fo common in our mountains of Ceven- nes. The quantity of porcelain which is made in China is immenfe. There are five hundred furnaces, and near a million of menj employed at King-to-ching, a province of Kian-fi. Our clays poffefs other advantages likewife: they ferve in the fulling-mills, to clean and full piece goods. The beft fuU lers* earth is foft and foapy. The name of tobacco-pipe clay is given to a white clay, which preferves its whitenefs in the fire, and refills a violent heat. f\ The fealed earth, or terrae figalatae, are clays upon which, fuperftition has beftowed chimerical virtues. They are im- preffed with a feal, for the purpoSe of deceiving the pubiick with greater certainty and effrontery. Almoft all the marles, more eSpecially thoSe which are Sound, in ftrata, appear to me to be compoSed oS the Same principles.' Much variation prevails with reSpea to the proporticu of theSe conftituent principles, and more eSpecially with regard ta the clay which predominates. species 11. Alumine, Silex, Pure Magnefia, and Iron. Mica, which reSults Srom the mixture oS theSe principles, has been improperly conSounded with talc. Mica is Soft to the touch, but not greafy like talc. It poffeffes in general a more brilliant and lefs earthy colour, if I may ufe thefe expreffions. The moft ufual colour of mica is white or yellow, inclining to red ; but it ha3 been found cf a greeniffi red, brown, and other colours. Jts texture likewife varies : it is Scaly, hmellated, or ftriated. Earthy Mixtures. Hornblende. 22S ft fometimes exhibits the form of a Segment oS an hexago- nal priSm. It is uSually found mixed with feld fpar, quartz, fchorl, &c. It almoft always exifts in the primitive rocks. Its fpecifick gravity is from 2.535 to 3.000 when charged with iron.— Kirwan. The colourlefs mica is infufible. It is only partially foluble in foda, in which it becomes divided with efferveScence ; it fu- Ses in the borate of foda, and in the phofphate of urine, with fqarcely any efferveScence. . The coloured micas are fufible.—:See de Saufiure. The Sragments of mica ' are employed, under the name of Cats Gold or Silver, according to the colour, as a fand for dry- ing ink upon paper. Its yellow colour, which confiderably refembles that of gold, often deceives the ignorant, who SuppoSe that they have dis- covered a mine oS this precious m'etal when they find a few pieces of this ftone. Mr Kirwan obtained from one hundred parts of colourlefs mica, thirty-eight filex, twenty-eight alumine, twenty magnefia, and fourteen oxide of iron. species iir. Alumine, Silex, Magnefia, Lime, and Iron. The mixture of thefe principles forms the horn-ftone, or horn-blende of the Germans. This ftone has a clofe grain, is difficultly pulverized, and is flightly flattened under the hammer. Its colour varies, which \z either black or of a greeniffi grey ; and its texture is in general either lamellated or ftriated. Its general charaaers are, partial folubility in acids without effervefcence ; a degree of hardnefs which never amounts to that of affording fire with the fteel; a fpecifick gravity never lefs than 2.66, and frequently as high as 3.88 ; a ftrong earthy Smell, which it emits when breathed upon, or is moiftencd with hot water ; a tenacity under the peftle, Sec.—See Kirwan, who diftinguiffies two varieties. variety 1. Black Home-Stone, Lapis Corneus Nitens Wallerii Its texture is either lamellated or grained. In the firft caSe it is Sometimes So Soft as to be capable of being Scratched with a nail. Its iurSace is Srequently oS a Shining greaSy appearance 3 and its Specifick gravity ib from 7.6 to 3.88. 222 Earthy Mixtures. Slate. Mr. Kirwan found that the lamellated fort contains thirty.. feven parts filex, twenty-two clay, fixteen magnefia two lime^ and twenty-three oxide of iron. variety II. Horn-ftone of a Greeniffi Grey Colour. This variety is either of a granulated or ftriated texture. Mr. Kirwan found its fpecifick gravity to be 2.683 ; it is harder than the preceding. The pale greeniffi hone is of this quality. Its grain is clofe ; it emits an earthy fmell, does not efferveSce with acids, nor Strike fire with Steel. It contains, according to Kirwan, fixty^ five parts of filex to the hundred, and its Specifick gravity is 6.664. SPECIES IV. Alumine, Silex, Carbonate of Magnefia, and of Lime with Iron. This fpecies, which comprehends the Slate or Schiftus, does, not appear to differ effentially from the preceding, fince its prin- ciples are the fame, and there is no other difference excepting what depends on the ftate of the lime and magnefia ; which in this laft effervefces flightly with acids, according to Kirwan^. The Slate is an argillaceous ftone, whofe principal charaaer is that of being divifible into very thin plates, capable of being wrought, and of receiving a certain polifh. The colour of the Slate is blue, of feveral degrees of intenfity: but this colour varies, and exhibits the following Shades. VARIETY I. Bluifh Purple Slate. This is brittle, and of a lamellated texture ; does not give fire with the fteel; its fpecifick gravity is 2.876; it affords a very clear and Silvery found, when divided into plates of an uni- form thicknefs ; it flightly efferveSces with acids when it is re- duced into powder, but not elSe. It Sorms black fcora: in a Strong fire. Soda affifts its fufion, and it is SuSed ftill more eafily with the borate oS Soda. From one hundred grains of this Slate Mr. Kirwan obtained forty-fix filex, twenty-Six alumine, eight magnefia, four carbon- ate of lime, and fourteen iron. Slates are ufed to form tablets, and to cover the roofs of houfes. Earthy Mixtures. Slate* 223 VARIETY II. Black Slate. This receives a considerably fine polifh when rubbed. The powder which is detached is white, and flightly efferveSces with acids. VARIETY III. Blue Slate. The blue Slate contains leSs iron than the firft variety. It is uSually hard, and of a very fine grain. VARIETY IV. Slate of a pale White Colour. It is leSs martial than the other varieties, and is more difficult- ly vitrified. Slates are uSed to Sorm tablets, and to cover the roofs of houSes. species v. Alumine, Silex, Pyrites or Sulphure of Iron and Carbonate of Lime and of Magnefia. The Schiftus which reSults from this combinatton is known by the name of Pyritous Schiftus. The pyrites are Sometimes diSperSed in the maSs, in the form of cubical cryftals. Sometimes they are difcovered only by an- alyfis, or by the Spontaneous decompofition oS the ftone. The mountains which afford this fchifti appear to me to be marine depofitions. Impreffions of leaves, of fifties, and other charaaers, are frequently obferved, which leaves no doubt of their origin. The pyrites foon efflorefce when the concurrence of air and water affifts their decompofition ; and the reSults then are Sul- phurick Salts, with baScs of magnefia, alumine, iron and lime. When the fulphate of alumine predominates, it is called alu- minous fehiftus. Moft of the alum ores wrought in Europe are of this nature. We have feveral in Provence which might be wrought -, the fchifti of Vebron in the Gavandan, thofe of Curvalle in the Albigeois, afford much alum by their decompo- sition. I24 Earthy Mixtures. Staff. YvTien the magnefian principle prevails, the effloreScence con- fifts oS EpSom Salt. I have diScovefed a mountain oS this kind in Rouergue, in the neighbourhood of Saint Michael. Thefe efflorefcences of alum or EpSom felt are always more or lefs abundantly mix:d with the Sulphates of" iron and of lime ; becaufe the fulphurick acid, which is formed by the decompo- fition of the pyrites, attacks and diffolves all the principles con- tained in the Schiftus. The decompofition of thefe pyrites may be haftened by expo- fure to air, calcination, Sec. SPECIE3 VI. Alumine, Silex, the Carbonate of Lime and of Magnefia, the Sulphure of Iron, and Bitumen. This fchiftus does not differ from the foregoing, excepting in confequence of its being impregnated with bitumen. It is ufu- ally of a black colour, which it owes to its bituminous princi- ple. Its confiftence is various ; it is fometimes divisible in flake?, and, its furface is either fmooth or rugged. Thefe are the fchifti which ufually form the focus of volca- noes. When their decompofition is favoured by air or water a prodigious heat is excited, hydrogenous gas is produced, which exerts itfelf againit the furrounding obstacles, and takes fire when it conies in contaa with the air. It is this inteftine la-. bour which occafions the fhocks and tremulous agitations that preced j the eruptions of volcanoes. The aaion of volcanoes muft be more lading and terrible, in proportion as the quantity of aliment and fhe focus are the more confiderable. We might, in- flrianeSs, place the pit-coals here, as they do not differ from this fchiftus but in their greater abundance of the bituminous principle. We daily obferve Spontaneous inflam- mation to take place in heaps of pyritous coal, and the Same effea happens iven in the midft, oS the veins which are wrought. Several examples of this may be pointed out in the kingdom of France. There even exifts at Cranfack in Rouergue a true lurning volcano. The mountain which contains the coal is prodigioufly hor, and flames are perceived Srom ti:r.e to time en its Summit, which iffue from its bowels. All thefe phenomena depend on the fame cauSe ; and from the Small artificial volca- no of Lemery, to the terrible eruptions of Vefuvius, there is no. nther difference thhi>. what confifts h: the magnitude of the r.i'.rX. Earthy Mixtures. Zeolite. 225 When the earthy and metallick principles, which form the bafis of bituminous fchifti, are Strongly heated, and almoft vitri- fied by the fire which produces their decompofition, they confti- tute volcanick produas. SPECIES VII. Alumine, Silex, Lime, and Water, This Stone which is called Zeolite, was unknown to mineral- ogists beSore the celebrated Cronftedt gave a deScription oS it. It is uSually of a femi-tranSparent white : but this colour is fometimes altered by metallick mixtures, and then it affumes all kinds of tinges. The name of Zeolite has been given to it on account of its property of forming a jelly with acids. This property has even been confidered as exclufive and charaaeriftick. But Mr. Swab has very juftly obferved, in the year 1758, that all zeolites do not poffefs this property; and Mr. Pelletier has proved in the twentieth volume of the journal de Phyfique that this property is not even peculiar to zeolites. The exiftence of zeolites in certain lavas has induced fome naturalifts to confider them as produced by the decompofition of volcanick earths. The moft beautiful zeolites come to us from the iflands of Ferro near Iceland. The form oS this ftone is conflant. The radii which compoSe it diverge as it were Srom a central point* and are diSpoSed aSter the manner oS a fan. The radius which terminates at the external furface, is found to exhibit a trihedral or tetrahedral pyramid. The white zeolite aSfeas two principal forms, the cube, and the tetrahedral prifm, fometimes flattened, and terminated by an obtuSe tetrahedral pyramid. Its Specifick gravity is from 2.1 to 3.15. The zeolite, expofed to a Strong heat, dilates, and Swells more or leSs, according to the proportion of water it contains, and at length melts into a porous feoria. Soda fufes with it with efferveScence ; rhe borate of foda diffolves it more difficultly; and the phofphates of urine have fcarcely any action upon .it.. Bergmann obtained from one hundred parts of the red zeolite of Adelfort, 83 filex, 9.5 alumine, 6.5 pure-lime, and 4 water. Letters on Iceland, p. 370. The white zeolite of Ferro contains, according to Pelletier, fifty filex, twenty alumine, eight lime, and twenty-two water.— journal de Phyfique. t. xx. 2..'.E 2x6- Earthy Mixtures* Gems\ Meyer obtained from a radiated zeolite 51.33 filex, 1*7.5; alumine, 6.66 lime, 17.5 water. Mr. Kirwan rightly obferves, that the cryftallized fpecies con- tain more Water than the others. GENUS V. Siliceous Mixtures. We Shall place in this genus all the Stones which give fire with the fteeh SPECIES Iw Silex, Alumine, Lime, and Iron intimately combined. The mixture of theSe Several earths Sorms the precious Stones Or gems. All the varieties of gems depend on their colour, hardnefs, brilliancy, weight, the proportion of their conftituent parts, and their more or lefs intimate combination. The numerous experiments of the celebrated Bergmann on precious Stones, have thrown the greateft light on their nature' and compofition, The analyfes of Meffrs. Gerhard, Achard, &c. by'exhibiting, a Stria identity oS principles, have confirmed: to us the reSults of the famous Swedifh chemift ; and it appears- that no reafonable doubt can now be formed againft thofe prin- ciples. As gems or precious ftones are distinguished in commerce by their colour, we fhall preferve this eftablifhed diftinaiom DIVISION I. RedGeras or Precious Stones—the Ruby, Garjtet, &c. 1. The ruby is a precious ftone of a fiery red colour, efeari- cal by friaion, giving fire with fteel, the moft ponderous and the hardeft of precious ftones. It cryftallizes in long hexahe- dral pyrarn/ds applied bafe tobaSe, without an intermediate prifm. . . Its fpecifick gravity is from 3.18 to 4.283. ft is not vitrified in the fire without addition ; and even refills the action of the burning mirror. Flame urged by vital air eafily fiifes it. It does not lbSe its colour at the degree oSheat which is Sufficient to melt iron. The borate of Soda and the phoSphates of urine fufe it. One hundred parts of ruby contain, according to Bergmann,, forty alumine, thirty-nine filex, nine lime, and ten iron, Earthy Mixtures. Gems. "227 Tlie lapidaries, with whom hardnefs and transparency are nhe principal charaaers of ftones, diftinguiffi rubies of different itolours ; and the inhabitants of Pegu, who confider tbernodifica- tions of the colouring principle as different degrees of maturity, •confound the topaz and the Sapphire under the name of rubies, of which they make three varieties. The name of Spinelle ruby, or Calais ruby, is given to the fame land of ftone, accordingly as its colour is of a pale or a deep red. This ruby cryftallizes in oaahedrons and has a lefs fpecifick gravity than the oriental ruby. 2. The garnet is tranfparent when it is not over-loaded with iron. It is in general obedient to the magnet, and of a yellow- ish red. The forms of the garnet appear to be derived from the rhomboidal parallelepiped, terminating in fix equal rhontbufes; They vary prodigioufly in colour, and thefe varieties are—r. The red, or the carbuncle of Theophraftus, according to Hill : h has a deep red colour. 2. The Syrian garnet, of a deep red, flightly tinged with yellow. 3. The violet garnet, of a beauti- ful red mixed with violet. All the garnets, whether denominated oriental or occidental, rank in one of thefe three chffes. Garnets change in-the fire into an enamel Of a blackiffi red. They are ftrongly attacked by the borate of foda, and the phof- phates of urine. Garnet is found in fmall grains in fand Stone (gres) or in fchiftus. The texture of the garnet is lamellated, and its fraaure vitre- ous. Its hardnefs is inferiour to that of other gems, but it exceeds that oS rock cryftal. Its Specifick gravity is from ^.6 to 4.188. One hundred parts of garnet contain, according to Mr. A- cbard, 48.3 Silex, 30 clay, 11.6 lime, 10 iron. They fome times contain tin, or even lead ; but this is fel- ^om.—Bergmann, DIVISION II. Yellow Gems or precious ftones—the Topaz, the Hyacinth, Sec. 1. The topaz is of a gold colour. We are acquainted with two principal varieties : the occidental or Brazilian topaz, which has the beautiful deep yellow colour of gold ; and the oriental whofe colour is lighter. The Saxon topaz refembles the latter. The oriental topaz lofes neither its colour nor its tranSparen- cy in the porcelain furnace. The Brazilian topaz lofes its pol- ifh, its hardnefs, and its tranfparency, but without melting. 228 Earthy Mixtures. Gems. The oriental topaz affeas the oaahedral form. The Brazilian topaz cryftallizes in rhomboidal tetahedrat prifms, grooved longitudinally. They are terminated by two tetrahedral pyramids with fmooth triangular faces. The Saxon topaz exhibits long fuboctahedral priSms, termi- nated by hexahedral pyramids mote or leSs truncated at their bafe. The Specifick gravity of the oriental topaz is to that of water as 40. j06 to 10.000 ; that of the Brazilian topaz is as 35.365 to 10.000.—See Briffon. The analyfis of one hundred parts of topaz afforded Berg- mann forty-fix clay, thirty-nine filex, eight carbonate of lime, and fix iron. 2. The oriental hyacinth is of a reddifh yellow colour. It is uSually cryftallized in the Sorm of a reaangular tetrahe- dral prifm, terminated by two quadrangular pyramids with jhombick faces. It lofes the brilliancy of its colours by the fire. M. Mongez confiders it as infufible by the blow-pipe. Mr. Achard affirms that he fufed it in a wind furnace. One hundred parts afforded Bergmann forty alumine, twenty- five filex, twenty carbonate of lime, and thirteen iron. That of which Mr. Achard has given the analyfes contained 41.33 alumine, 21.66 filex, 20 carbonate oS lime 13.33 ir°n. Hyacinths are Sound in Poland, in Bohemia, in Saxony, Ve-« lay, &c. The hyacinth, rendered white by fire, is known by the name of Jargon. According to Mr. Lavoifier, the hyacinth of Puy in Velay becomes white in fire urged by vital air. Its fpecifick gravity, compared with that of water, is. as 36.873 to 10.005.—See Briffon. DIVISION III. Green Gems—the Emerald, Chrysolite, Beryl, &c. 1. The Peruvian emerald is of a green* colour, elearical by friaion, and cryftallized in hexahedral prifms, truncated flat at each extremity. The jafpers, or green fchorles, which are called prafeor moth- er emerald, have often been confounded with the emerald. Cryftals of emeralds are frequently found inferted in the gangues of quartz, and even of Spar. According to Mr. Sage, the more tranfparent emeralds are, the lefs their colour is changed in the fire. They become opake, and, of a greeniffi white. There are Some which are reduced to enamel at their Surface. Earthy Mixtures. Gems. 229 Mr. Darcet affirms, that in his experiments the emerald loft its transparency, and moft of its colour, but that its Sorm was not changed. In the experiments at Vienna in Auftria, the emerald melted in twenty-four hours; and at Florence ,it was Speedily SuSed by the burning mirror. Mr. De Sauffure fufed it by the bjow-pipe into a compaa grey glaSs; and Mr. Lavoifier, with a ftream oS vital air, SuSed it into an opake milky bubble, whoSe internal part was greeniffi. Its Specifick gravity, compared with that oS water, is in the proportion oS 27.755 to io.oep. One hundred parts afforded Bergmann fixty alumine, twenty- four filex, eight lime, fix iron. Achard obtained 60 alumine, 21.26 filex, 8.33 lime, and 5 iron. The emeralds which come Srom America are called occident- al. Peru and the Brazils afford the moft beautiSul: they may be diftinguiflied by the colour ; that oS Peru is of a fatin colour or appearance ; the colour oS the Brazilian is lefs lively. The emerald is the Softeft of gems, and may be Scratched by the topaz, the Sapphire, &c. 2. The chrySolite or peridot is of a green colour, flightly in- clining to yellow. Its form is that of an hexahedral pyramid with unequal fides, frequently ftriated, and terminating in two hexahedral pyramids. Mr. Sage affirms that this ftone fuffers no alteration in the moft violent heat, its colour not being So much as altered : and the Same chemift pretends that Wallerius did not operate on a true chrySolite, becauSe he affirms that it loft its colour. Meffrs^ Lavoifier and Erhmann SuSed it into a white, dirty, dull-colour- ed glaSs, by the affiftance of vital air. The fpecifick gravity oS the Brazilian chrySolite is in propor- tion to thjt of water as 26.923 to 10.000.—Briflbn. Maffes of granulated chrySolite of various Shades oS green col- our are found in the prifmatick baSaltes, and in feveral other volcanick produas. TheSe chrySolites are common in the volcanoes oS our province. Mr. Sage received Srom Auvergne an hexagonal priSm fix inches in dia,meter, Sormed by the union of chryfolites of different col- ours. 3. The beryl, or aqua marina, is of a very bluiffi green. The Saxon beryl, as well as that oS Siberia, Sent to Mr. Sage by Mr. Pallas, exhibits hexahedral, ftriated, truncated priSms, of a lamellated texture. The pure beryl decrepitates in the fire, loSes its tranSparcnce, and is Sufible by the blow-pipe. £3» Earthy Mixtures. Cryftals. Its Specifick gravity, in proportion to water, is 3535.48910 10.000, for the oriental aqua marina ; and 27.227 to 10,000 for the occidental.—Briffon. A blue aqua marina, in long, flattened, tetrahedral priSms, grooved longitudinally, and united fideways, is found among the granites of Spain, and on the declivity of Saint Symphorien, near Lyon. This Stone is very common at Baltimore in Amer- ica. DIVISION IV. Blue Gems—Sapphire. The colour of the Sapphire is a Sky-blue. The Sapphires of the fcrook d'Expailly have a green tinge, and change in the fire in the fame manner as thofe oS the Brazils ; whereas the oriental fapphire is not changed in our ordinary furnaces. Mr. Erh- mann caufed the clear oriental Sapphire, and of a perfea blue, to run into an opake white globule by fire excited by the fir earn of oxigene. The experiments of Meffrs. Achard, Sage, D'Arcet, Erhmann, Lavoifier, Geyx, Quift, &c. exhibit a variety of refults in the analyfes of gems by fire, which can be attributed only to the manner in which they applied it ; and more efpecially to the very variable nature of the ftones upon which they made their experiments. The oriental Sapphire, and that of Puy, have the form of two very long hexahedral pyramids joined and oppofed bafe to bafe, without any intermediate prifm. Mr. Sage, Saw a Sapphire in a ' rhomboidal cube, or fix Sided figure. The Sapphire analySed by Bergmann afforded him per quintal^ 58 parts alumine, 35 filex, 5 lime, and 2 iron. ^ Mr. Achard obtained Srom his analyfis 58.33 alumine, 33.33 filex, 6.66 lime and 3.33 iron. The Specifick gravity of the Sapphire of Puy is in proportion to water as 40.769 to 10.000 ; that of the white oriental Sap- phire is as 39-911 ; and that of^ the Brazilian Sapphire is as 3*-3°7- SPECIES II. Silex, fometimes pure, but oftener mixed with a very fmall quantity of Alumine, Lime, and Iron. This Species effentially comprehends quartz and rock cryftal. The name of Quartz is given to the opaque, or irregularly- c5gured vitrifiable ltone ; and that of Rock Cryftal to the fame Earthy Mixtures. Cryftal*. jot ftone cryftallized. As the principles are nearly the fame, this. circumftance naturally eftablifhes a divifion of thefe ftones into two claffes. DIVISION r. Rock-Cryftal. Rock cryftal is a ftorie which exhibits filex in a ftate more nearly approaching to purity than in any other natural Subftance yet obServed. Mr. Gerhard has even Sound Specimens perfea- ly pure ; but one hundred parts of cryftal, ftriaiy analySed by Bergmann, afforded him ninety-three parts filex, fix alumine, and one lime. The ordinary form of rock cryftal is that of an hexahedral prifm, terminated by pyramids of an equal number of fides. The varieties of the feveral cryftals may be reduced to this geo- metrical form.—Confult Rome de Lifle. Quartz cryftallizes likewife in cubes. This form exifts in va- rious Specimens in the cabinets of Germany -x and Mr. Macquart brought a Specimen with him to France. The Sormation of this cryftal appears to be owing to water, for we often find this fluid in the internal part of cryftals ; and they are evidently formed in the clefts and cavities of the primi- tive rocks, by the concurrence of this agent. But hitherto we have acquired very little knowledge refpeaing the circumftances of this operation. Bergmann obtained rock cryftals by dlfibfving filex in the flu- orick acid, and fuffering it to evaporate flowly. I left on the tables of my cabinet of mineralogy a receiver and a retort, in which I had made the acid of fluor ; and when I had occafion, two years afterwards, to infpea this apparatus, I found the re- ceiver almoft entirely corroded, and its interiour*furface lined with a fubtle powder, in which thoufands of rock cryftals might be difcerned. Mr. Achard informed the pubiick that he had obtained rock cryftals by caufing water impregnated with carbonick acid to filtrate through clay. Mr. Magellan even prefented thefe cryf- tals to the Academy at Paris ; but the experiment though re- peated with the greateft care by Several chemifts of the capital, was not attended with the fame reSults. Since that epocha, Mr. De Morveau, having incIoSed rock cryftals with a bar of iron in a bottle fillej with gafeous water, perceived a vitreous point fixed to the iron, which he fuppofed 23* Earthy" Mixtures. CryBah, to be a rock cryftal formed by this operation ; fo that he con- fiders iron as a neceffary intermedium to enable the carbonick acid to diffolve quartz. This conSequence oSMr. De Morveau appears to agree with many faas which have been colfeaed concerning the Sormation oSrock cryftal. We fee it formed in ochreous earths ; and I poffefs ochres in my colfeaion which poffefs many of thefe fmall tAVo-pointed cryftals. It appears to me that it is not neceffary to Seek for a folvent for filex, in order to explain the forrriation of rock cryftal. The fimple divifion of this earth appears to me to be fufficient for the purpofe : and I could bring numerous faa's to fupport this aflertion.—See the article Cryftallization. It is proved by the obfervations arid experiments of Mr. Genf- fane, that a quartzofe gurh is formed by fimple tranfudation upon rocks of this nature ; and the fame naturalift has taken notice that, when the gurh is worn and depofited by water, rock-cryftals are formed. The waters which work their way through the quartzoSe rock's of the mine of Chamillat, near Ptahche les Mines in Franche-compte, form quartzofe flalac- tites to the roof of the works, arid even upon wood. The ex- tremities of thefe ftalaaites which' have riot yet'affumed a folid confiftence, are of a granulated and' cryftallirie fubftance eafily crufhed between the Singers. Iri thefe cavities, called craques by the miners, a fluid gurh is often found, and ftill offenef cryftals ready formed. I have feen at Saint Sauveur, in the work of La Boiffiere, near Bramebiaou, feveral incruftations of gurh on the fides of the gallery ; and thefe Spreading incruftations were terminated by well-formed cryftals, wherever the wall overhung or deviated from the per- pendicular. This gurh, when handled, and minutely exairiiri- ed, had no other appearance than that of a filiceous pafte of considerable purity. The fame effeas appear to take place with regard to rock cryftals, as with the calcareous Spars. Thejr'are formed whenever their principles, in a ftate of extreme divifion and attenuation, are SuSpehded by water, and depofited with all the circumftan- ces which nature requires in order that cryftallization may take place. I do not even think it neceffary to recur to the property which water poffeffes of fenfibly diffolving fifex, to explain the formation of thefe cryftals : and we fhall refer the formation of quartzofe ftalaaites, agates, &c. to the fame caufe. Rock cryftal is frequently coloured by iron, in which cafe it affumes peculiar Shades which have been denoted under differ- ent names. We Shall place them here as Simple varieties. Earthy Mixtures. Cryftals. *33 VARIETY I. Red Cryftal—False Ruby. It is frequently mixed with different Shades. Its colour is tieftroyed by fire, according" to Mr. D'Arcet. It is found in Barbary, in Silefia, in Bohemia, &c. When it is of a dull red, it is called the Hyacinth of Com- poftella. * VARIETY it. Yellow Cryftal—Bohemian Topaz. It has fometifties a tinge inclining to yellow ; its colour is bften internal only. It is found in Velay, near Briftol in Eng- land, &c. VARIETY III. Brown Cryftal—Smoky Topaz. This brown tinge varies from a light brown to a deep black. It is affirmed that they may be rendered clear by boiling them in tallow.—See Journal de Phyfique, t. vii. p. 360. It is found in Switzerland, in Bohemia, in Dauphiny, &c. VARIETY IV. Green Cryftal---False Emerald. * This is the moft Scarce and the moft precious of coloured cryftals. It found in Saxony and Dauphiny. VARIETY v. - Blue Cryftal—Water Sapphire, It does not appear to differ from the true Sapphire, excepting in being lefs hard. I have feen a Specimen which had this col- our. It is Sound in Bohemia, in Silefia, and at Puy in Velay, which has cauSed it to be called the Sapphire of Puy. 2...F 2 34 Earthy Mixtures. Quartz. VARIETY VI. Violet Cryftal—the Amethyst. tts colour'is more or lefs deep ; and it affumes a confiderable' brilliancy by polifhing. When the cryftal is only half colour- ed*, it is called Prime de Amethifte. It looSes its colour by a ftrong" fire, according to Mr. D'Arcet. This cryftal is found of fuflr- cient magnitude to form columns of more than one foot in height, and feveral inches in diameter. DIVISION Hi Quartzv Thofe Specimens of filiceous ftone in which no regular form appears, and which we here comprehend under the name of Quartz, poffefs various degrees of transparency. Its colour differs prodigioufly ; and it may be diftinguiflied into varieties and" Shades perhaps more numerous than in rock cryftal itfelf. It feldom forms entire mountains,- but- almoft always inter- feas, by veins more or lefs wide, the mountains of primitive fchiftus. At all events, I have made this observation in every mountain of this kind which I have examined. The blocks of quartz, detached by waters, are rolled, rounded, and depofited iri the form of large Stories on the banks of rivers. The fame ftones, more attenuated, form the quartzofe pebbles -, and thefe, ftill more dfvided:, produce Sand. This Stone is very reSraaory. It is uSed as the bafis* oS bricks employed in the conftruaion oS glaSs furnaces. For this purpofe it is calcined to whitenefs, and in that ftate thrown in- to water. By this means it may be eafily reduced to powder, and difpofed to form a combination with clay. Quartz, well pounded, and ufed in the compofition of bricks,- does not equally refift the impreffion of fire, if the precaution of calcining it, and extinguishing it in water has not been taken. I' have obtained a proof of this faa, by employing the fame kind of quartz in both ways. This fand forms an excellent mortar with good lime ; arid',, when fufed-with alkalis, it produces a very beautiSul gjafi. Earthy Mixtures. Flints. *& SPECIES .III. Silex, Alumine,Lime, andiron, intimately mixed. The ftate of finenefs in the constituent principles, and their .more or leSs intimate mixture or amalgamation, appear to us to •eftablifh two divisions among the ftones of this fpecies. We Shall Accordingly diftinguiffi them into coarfer flints and finer flints. The firft form gun flints, petrofilex, &c. ; the Second compre^ -hend agates, calcedonies, &c. BIVISION i. The Coarfer Flints. In this place we fhall arrange two ftones which appear to dif- fer only by a more or lefs eyident degreepf transparency. The filex, or flint properly fo called, is femi-trapSparent, when very thin, as for example at its adges : .the petrofilex has a more opaque colour. i. Gun Flint.—The gun flint gives fire with fteel: its col- pur is uSually brown ; and its SurSace very frequently exhibits a whiter colour than the middle, and lefs hard than the nucleus of the ftone. This external part fticks to the tongue, and indi- cates a commencement of decompofition. The abbe Bacheley hasafferted that marine produaions, Such as polipiers, Shells, &c are capable of paffing to the ftate oSgun flint.—Journal de Phyfique,Supplement, 1782, t. xxv. The Specifick gravity oS gun flint is from 2.65 to 2.7. This ftone does not mejt in .the fire ; but it becomes white and brittle by repeated calcinations. The common brown filex afforded by analyfis to Mr. Wieg- leb, per quintal, eighty filex, eighteen alumine, and two iron. 2. Petrofilex.—The colour of petrofilex is a deep blue, or a yellowith grey. It is interfperSed in veins through rocks ; and fiom this circumftance it derives its name. Its Specifick gravity is Srom 2.59 to 2.7. It becomes white in the fire like gun flint; but it is more fu- fible, Sor it flows without addition. Soda does not totally dif- folve it in the dry way ; but the borate of foda, and the phof- phates of urine, diffolve it without efferveScence. Mr. Kirwan obtained from a petrofilex, uSed in the manufac- ture oS porcelain by Mr. Lauraguais, Seventy-two parts filex, twenty-two alumine, and fix lime, in the quintal. 136 Ea,.yy Mixtures. Flints. division 11. The Finer Flints. This divifion exhibit? feveral ftones, which, though diftin^ guilhed by names and a different value, are nevertheless only varieties of each other. We Shall content ourSelves with enu- merating the chief. 1. Agate.—-This is a femi-tranSparent filex of a very fine body. Its texture is vitreous; and its hardnefs fuch that it refiSts the file, gives fire with the Steel, and takes the moft beau- tiful polifh. The agate when expofed to the fire, lofes its colour, becomes opaque, and does not melt. The varieties of agates are infinite. They are founded on the colour; and they are diftinguifhed into clouded, punauated, fpotted, Irifed, herborized, moffyi &c See Daubenton.—The name of Onyx is giverl to that kind of agate which is formed by concentrick bands. Mr. Daubenton has proved that the agate which has received the name of md'ffy, is really coloured by fmall moffy vegetation. The pureft agate is white, tranfparent, and nebulous. Such is the oriental agate, which befides appears as if it had protu-i berarices or knobs on its Surfaces. 1 Its fpecifick gravity is 2.64. I confider the agates, and the other flints concerning which we Shall proceed to treat, as quart- zofe ftalaaites. The fides of geodes which are agatized, and the ftrata of thofe flints which are found in places where infiltra- tions produce rock cryftals, appear to me conclufive in favour of this docirine. The agates have the fame relation to quartz as the alabaffers to calcareous ftones, and the theory of their formation is the fame. Mr. Dortheshas exhibited many proofs of this theory refpecVmg the formation of theSe ftones. 2. The Opal.—The Semi-tranSparent agate of a milky white- nefs, which exhibits a glittering, changeable, internal colour of a blue, red, and green tinge, is known by the name of Opal. That which comes from Hungary has a kind of greyifh clay for its gangue. The moft beautiful opal is the oriental opal; fome- times called the fpangled opal, becaufe its colours appear like equal fpots diftributed over its whole furface. Thefe opals have received various names, according to the colours they reffea. The chatoyant ftones, or fuch as vary their colour according to the pofition of the light, and the eye of the obferver, are vari- eties of the opal. Such are the girafol, the cat's eye, the fifh's eye. Earthy Mixtures. Flints., 237 The reffeaed rays of the girafol are weak, bluifh, and mixed with an orange yellow. This ftone has been found in the lead mines of Chatelaudren in Britanny. The moft obvious char- aaer of the girafol is, that it exhibits in its internal part a lumi- nous point; and reffeas the rays of the light in whatever pofi- tion it may be turned, when it is cut into a globe or hcmifr fphere. The cat's eye has a point near the middle, from which proceed, in a circle, greeniffi trapes of a very lively colour. The moft beautiful ftones of this kind are of a grey and mort- dore colour. They come from Egypt and Arabia. The fifli's eye does not differ from the cat's eye excepting in its colour, which is bluifh : it is found at Java. , 3. Calcedony.—The calcedony is a femi-tranfparent agate of a milky whitenefs, differing Srom the foregoing in not pof- feffing the chatoyant property, or changeableneSs of colour. It has been found in the jnines of Cornwall, in ftalaaites of fingular elegance. Thefe calcedonies are almoft always covered with protuberances like the flalagmites. The protuberances appear to be formed by the fucceffive ap-; pofition of feveral ftrata or coatings. In Monte Berico, in the territory of Vicenza, geodes of cal- cedony are found which inclofe water. They are called En- hydria. I poffefs in the Mineralogical Cabinet of the povince, calcedo- nies of Auvergne, which appear to be chryftallized like rock- cryftal. The cryftals have all the fat and unauous appear- ance of the fame balls which are difperfed on the rock ; but when they are broke, it is feen that the appearance aroSe Srom povering of calcedony over the cryftal oS quartz. Mr. Bindheim analySed calcedony, and Sound, in the centen- ary, 83.3 filex, n lime, 1.6 alumine, and a Small quantity of iron.—Schrift. Natur. For. Free. t. iii. p. 429. Mr. Darcet did not Succeed in fufing calcedony, but it loft its colour. Calcedony has often a ffiade of blue, yellow, or red. Mr. De Carozy and Mr. Macquart obferved in Poland the transformation of gypfum to the ftate of calcedony.r—See the Effai de Mineralogie par M. Macquart premier memoire. Cacholong. The white and opaque calcedony is known by the name oS Cacholong. Its texture refembles that oS quartz, and it becomes white in the fire. This Stone is capable of a fine polifh. It is Sound on the banks of a river named Cach, near the Kalmouks of Bucharia, in whofe language the word, cholong fignifies ftone. -^ Earthy Mixtures. Jafper. An imaginary value has been given to a modification of the Cacholong, which has the property of becoming tranfparent after having been plunged in water. This is called Hydro- phanes, Lapis Mutabilis, Oculus Mundi. Mr. Dantz brought hydrophanes to Paris, which became tranfparent when plunged m water. Mr. Gerhard, on the 2?th of Auguft, 1777, read to the Acad- emy of Berlin, Obfervations on the Hydrophanes. He found that this ftone contained two thirds of clay, and one third of fi- lex. This celebrated naturalift affirms that the hydrophanes was known to Boyle, who Saw one oS them, about the Size of a pea.. fold in London for two hundred pounds Sterling. The hydrophanes is Sufible in the fire. Soda diSfblves it with ^effervefcence ;. the borate of foda, and the phofphates of urine, without efferveScence. 5. Carnelian. Sardonyx. The carnelian is a Species of agate, nearly transparent. It is called Carneole when it has the col- our of flefh. Its hardnefs varies prodigioufly Thofe which are white or yellowifli are not fufficiently hard to give fire with the fteel. "When ignited it lofes its colour, and becomes opaque. The moft beautiful fpecimens refemble the garnet. Its fpecifick gravity is from 2.6 to 2.7. The fardonyx is a femi-tranfparent filex, of an orange colomy more or lefs deep. It is knobbed like the calcedony ; and pof- feffes the hardnefs and fpecifick gravity of that ftone. Its habi- tude in the fire refembles that of the agate. In the Royal Wardrobe of France there are veffels oS Sardonyx, of an afton- ifhing magnitude and beauty. The famous murrhine vafes were, of Sardonyx. Sage, t. ii. p. 163. species iy. Silex, Alumine, and Iron. Jafper is one of the hardeft ftones we are acquainted with. It is fufceptible of the fineft polifh ; and its colour varies pro- digioufly, which has occafioned it to receive the names of San- guine Jafper, Green Jafper, Flowered Jafper, &c. , Mr. Wedgwood allured Mr. Kirwan that Jafper hardens in the fire without melting ; and Mr. Lavoifier could not obtain a per- fea fufion by the affiftance of oxigenous gas. The furface only becomes vitreous. Mr. Gerhard afferts that fome fpecies are fufible j and Mr. Kirwan attributes this property to the mixture oS lime and iron which produces the fufion. Etirthy Mixtures. Tourmrtline. 2$ its exceffive hardnefs has induced the Savages of Canada to a» vail themfelves of it in the fabrication of the heads of javelins. Mr. Dorthes has found among the worn ftones of the Medi- terranean Shore, javelin-heads of porphyry, jafper, horn ftone, Schorl, variolite, &c. probably fabricated by the ancient inhabi- tants, the Gauls. TheSe javelin-heads are commonly known by the name of Thunder-ftones, and are diftinguifhed by lkhologifts by the name of Ceraunites. SPECIES t. &lex, Alumine, Lime with a fmall portion of Magnefia, and Iron. This fpecies comprehends all the fehorls ; and moft of the volcanick produas. As the tourmaline is evidently nothing more than a variety of the fchorl, we fhall place it here, though analyfis has not difcovered an atom of magnefia in it, and tht nature of its principles confounds it with precious ftones. Moreover by placing it between theSe and the Schorls, it poffefc. fes a Situation'affigned to it,-as well by its natural charaaers as by its conftituent principles. I. The Tourmaline. This Stone poffeffes the tranfaparency oS the Schorl. Its appearance and Sraaure are vitreous, its tex- ture lamellated, its hardnefs fo confiderable as to cut glafs. When heated to the two hundredth degree c. Fahrenheit, it be- comes efearical : a ftronger fire deprives it of this1 property. It is fufible by the blow-pipe, with ebullition : the pure tourma- line was meked into a black glafs, in the experiments of Mr. Lavoifier. Tourmalines have been found in the ifland of Ceylon, in Tyrol, and in Spain. Its form is that of a nine-fided prifm, terminated by two flat trihedral pyramids. Mr*De Joubert poffeffes one whofe prifm is feven inches and a half long, and eleven inches in circumference. The prifmatick tourmaline has no efearick effea but accords ing to the direaion of Its column : the Sphere of aaivity of the Spaniffi tourmaline is moreextenfive than that of Tyrol. The valuable refearches of Bergmann upon this ftone rmy be confulted in his differtation concerning its analyfis. Mr. Tofani has annexed a let of interefting notes to his translation of this work. The refults of Bergrruiin's analyfis exhibits its component parts in the following proportion : i. The tourmaline of Tyrob contains alumine forty-two, fi- 'ex forty, lime twelve, iron fix. 240 Earthy Mixtures. Schorls. 2. The tourmaline of Ceylon, alumine thirty-nine, filex thir- ty-feveri, lime fifteen, iron nine. 3. The tourmaline of Brazil, alumine fifty, filex thirty-four, lime eleven, iron five. The fpecifick gravity of the tourmaline of Ceylon is 30.541,1 that of Spain and of Tyrol is 30.863, water being 10.000— See Briffon. II. Schorl. The diftina properties of Schorl are, an appear- ance of femi-vitrification, fufibility in a moderate fire, and hardnefs approaching to that of cryftal. There are few Stones which exhibit a greater variety of form or colour. They enter into the compofition of porphyry, of ferpentine^ of granite, and are very frequently foiyid with the rrfUgnefian ftones. We fhall diftinguiffi the Schorls into cryftallized and irregular- ly Shaped Schorls. A. All the varieties which depend upon colour may be re- duced to four 1. Black Schorl.—The black Schorl is found chiefly in gran- ites. It has almoft always the form of prifms more or lefs per- fea. The number of fides of thefe prifms is various; they are fometimes grooved ; they fometimes terminate in trihedral cMufe pyramids, placed in contrary direaions ; in fome places they are found feaeral inches long, and the union of thefe f ifms frequently forms groupes of feveral in diameter. Their b; ick colour is more or lefs deep. When urged by fire, they become refolved into a black uniform glafs of an imperfea fluidity like pafte. The analyfis of the black prifmatick Schorls of Gevaudan af- forded me, per quintal, fifty-two filex, thirty-feven alumine, five lime, three magnefia, and three iron. 2. Green Schorl—This variety ex^bits the feme form, and the fame modifications ; but the moft common of its crystalli- zations is that of a tetrahedral prifm, terminating in fhort pyramids likewife tetrahedral. 3. Violet Schorl. This variety was difcovered in 1781 by Mr. Schreiber, below the grotto of Aunis; fituated at tlile dif- tance of one league from Bourg D'oifan in Dauphiny. Mr. De la Peyroufe likewife found it at the Peak of Drethz, in the Py. renean Mountains. . This fehorl poffeffes a certain degree of tranfparency. It is cryftallized in rhomboids ; its texture is lamellated ; two oi the rhomboidal planes of each pyramid have their faces ftriated parallel to each other. Earthy Mixtures. Voicanick Pr-odutls. 24-t Schorl lofes its colour in the fire, and one thirteenth of its weight; it becomes of a greyifh white ; and with a Stronger degree of heat it fwells up, Subsides, and Sorms a black enamel. Its Specifick gravity is 32.956 according to Briffon. 4. White Scorhl.—This variety has been found in the moun- tain:; 0S Corfica, Dauphiny, and the Pyrenees. It is oS an opaque white colour, and vitreous appearance ; and is Sound in cryftals on the Surface of certain ftones of the nature of the lapis olla- ris. I have Seen a layer of this fchorl between amianthus and the lapis ollaris. It melts iri the fire into a white enamel. The analyfis of this Schorl Stbm the Pyrerieari Mountains af- forded mfe, per quintal, fifty-five parts filex, twenty-two alumine, thirteen magnefia, arid feven lime. B. The fchorl in conneaed maffes nearly approaches the jafper in its external charaaers. It may be diftinguifhed how- ever by its Sraaure, which is of a drier grain, and exhibits a ffiSpofition to cryftallization. This ftone Serves as the bafis to Several porphyries. The variolite of Diirance, a ftone Singu- lar on account of the fupef ftitions to which it. has given riSe, is a Schorl in the mafs, coveted with grains of the fame nature as the groundj but of a clearer greeri. . Mr. Dorthes has obferved Varlolites oh the eoaft of our Me-* diterranean fea *, and affirms that this ftone iri its decompofition undergoes changes of colour which fucceed each other in the Order of the folar fpearum. III. Volcanick produas.—The principal produas of volca- noes are bafaltes, lava, and terra pozzolana. Thefe fubftances are abfolutely of the fame nature ; but they are principally dif- tinguifhed by the name of Bafaltes when their form is regular. When they have no determinate figure, they are denominated Lavas ; and when corifiderably attenuated they are distinguish- ed by the name of Terra Pozzolana. Bafaltes is distinguished into the prifmatick baSaltes with a number oS fides Srom three to Seven ; the baSaltes in tables and the Spherical baSaltes. Lava is diftinguifhed into compaa lava, porous lava, twifted lava, lava* in tears, &c. Several naturalifts have claffed the baSaltes with the Schorls, and Some oS them have affigned the Same origin to both. It appears nevertheless to be generally agreed that baSaltes is a produa of fire. It Sometimes differs from fchorls in its chemical analyfis, and alfo in the circumftance of its not always affording magnefian •r:h. 9...G 34* Earthy Mixtures. Lavas: The colour of bafaltes is of a deep green, almoft conftantly covered or enveloped with a ferruginous cruft lefs black thar> the internal part. The iron is in the ftate of ochre. Its form is conftantly prifmatick, which is the natural effea of the contraaion which it fuffers in cooling. , Bafaltes is converted by fire into a moft beautiful black glafs. This property, which is admitted by every chemift, induced me to SuSe it, and blow it into bottles. The attempt was perSeaiy fucceSsful at the glaSs-houSe of Mr. Gilley oS Allais, and at that oS Mr. Giral of Erepian. I ftill preServe the firft veffels which were blown oS this Subftance : they are the moft beautiSul black, aftoniffiingly light, but without transparency. Encouraged by this firft SucceSs, I requested Mr. Caftelveil, the proprietor of another glafs-houfe, to undertake fome experiments ; and in confequence of various trials we Suc- ceeded in Sabricating bottles of an olive green, in which the moft extreme lightnefs, and a truly aftoniffiing degree of Solid- ity, were united. Pounded bafaltes, foda, and fand, in nearly equal proportions, formed their compofition. The properties of thefe bottles, as proved" by my own experiments, as well as by thofe which Mr. Joly De Fleury, at that time comptroller-general, or- dered to be made, render them of the greateft value in com- merce ; and Mr. Caftelveil was unable to fupply the numerous orders he received. This manufaaure fupported itfelf with fuccefs for two years ; but at the end of that time the Superi- ority of the bottles ceafed to be the fame; the manufaaurer received the reproaches of the confumer ; this Superb eftabliffi- ment gradually fell off, and was at length abandoned. Since that period I have made feveral experiments in the large way, from which I have obtained refults that may be of fervice to Such as are defirous of following this manufaaure. i. The nature of the combuftible ufed in glafs-houfes has a prodigious effea in modifying the refults of experiments. The fame bafaltes which Mr. Caftelveil confidered as too refraaory in his Surnace heated by wood, was Sound of too fufible a nature by Mr. Giral, who was in the habit of ufing pit-coal in his glaSs works. The Sormer riianufaaurer accordingly made his glafs by adding foda to the lava, whilft the latter mixed it with a very refraaory fand. 2. The Same lava, SuSed without addition, may be blown in one glaSs-houSe and not in another. This irregularity appeared to me at firft to depend effentially on the fkill oS the workmen ; but I have been fince convinced that it is totally independent of that circumftance. In a Surnace which is ftrongly heated, the fufed lava Some- times becomes fluid like water, and drops from the iron-tube; Earthy Mixtures. Lavas. 343 as foon as it is colfeaed. The Same lava, when fufed in other furnaces, will preServe a Sufficient degree oS confiftency to admit of being blown. I am myfelf well affured that the lava might be be wrought in any glafs-houfe whatever provided the moment was feized in which the pafte was neither too fluid nor too thick to be wrought ; but thefe attentions are too delicate, and too minute, to be obferved in works in the large way. 3. The hardeft bafaltes affords the moft beautiful glafs •When it is contaminated with foreign principles, fuch as the nodules of lime, the glafs is brittle, and has not a fufficient con- neaion of its parts. This circumftance, in my opinion, was the •caufe of the bad quality of the glafs, which produced the failure in Mr. Caftelveil's manufaaory. 4. *I have feen very hard bafaltes interfperfed withblack in- fufible points, infomuch that thefe points became enveloped in the vitreous pafte without any perceptible alteration. The vol- canick mountain of Efcandorgue near Lodeve afforded me this variety of bafaltes. In the article Verrerie of the'Encyclopedie Methodique, may- be feen the various refults which we have obtained with Mr. Allut, in feveral experiments made in common in the royal glafs works of Bofquet and elSewhere. I fhall conclude, from the obfervation which my experiments •have hitherto afforded— 1. That lava may be ufed as a 'flux in glafs-houfes to diminifh the confumption of foda. This is the fingle purpofe I at that time propofed to myfelf, and I have clearly accomplished it. 1. By the reSults oS experiments which have Shewn that refrac- tory Sand becomes fufed in the glafs furnace by a mixture of lava. 2. By the effeas obtained in all the works in the large way, in which the addition of lava permitted a diminution in the proportion of foda. 2. It is very difficult to eftablifh a rigorous procefs, applicable to all circumftances, by which lava may be wrought without ad- dition. My bottles into which the lava entered as a component part, were fcarcely known, before it was published that they were formed of .lava without addition ; nothing more being faid to be required than to fufe the lava in order to form bottles. This Strange report affeaed me very little in the principle; be- caufe I had neither fpoken, written nor printed any thing which was capable of giving authority to fuch an errour ; and I was content to reply to all perfons who demanded information, by informing them that experience had taught me that an addition of lava diminifhed the proportion of foda in the compofition of glafs, and that this new principle rendered the bottles lighter and Wronger. 244 Earthy Mixtures. Trapp. Chryfoprafe. 3. That the only advantage which can be derived from fofing lava without addition, is to pour it into moulds, to form paving ftones, chimney jams, Sec. "The facility vyith which it is fufed by the affiftance of pit-coal, would render thefe works of fma.I expenSe ; and it might eafily be decorated by incrufting :t with metallick colours. 4. That the difference in the nature of volcanick produas produces fuch a variety in the refults of their fufion, that I con- fider it as impofljble to affigna conflant and invariable procefs, fey which the fame refult may infallibly be obtained. This cir- cumftance renders it neceffary to make preliminary trials in all caSes wherein it is intended to ufe bafaltes in the fabrication of bottles. The bafaltes has been confidered as fimilar to a ftone known by the name oS Trapp; it reSembles it in feveral effential prop- erties ; the colour, form, weight, and the nature of the compo- nent parts of each, appear to authorize us in confounding them together, as Bergmann has proved by the fine comparifon he has made of thefe two ftones, in his analyfis of the volcanick pro- ducts of Iceland. But this'fame chemift has Shewn that they differ in feveral other points of view. The trapp exhibits no charaaer which, can give ground to fuf- feet that its origin is yqlcanick ; it is found in Sweden, in the primitive mountains, and upon Strata of gTanite and fchiftus, and fometimes even upon banks of calcareous ftone. The trapp cjf the mountains of Weflrogothland is ufually in the form of fquare irregular cubes ; and it is indebted for its denomination to this refemblance to the fteps of a flair cafe. It likewife exhibits the form of a triangular prifm, though ftldom ; and fometimes it refembles immenfe columns. The trapp afforded Bergmann the fame principles, and nearly \n the fame proportion, as the bafaltes. The difference is Scarce- ly the hundredth part; and this variation is frequently found in pieces of the fame bafaltes. SPECIES VI. Silejc, Lime, Magnefia, Iron, Copper, and the Fluorick Acid. This combination forms the chryfoprafe. Its colour is a femi- tranfparent apple green, and it is harder than the fufible Spars and quartz oS the Same colour. The fire deprives it of its green colour, renders it white and opaque, and forms by the affiftance of vital air a compaa and milky globule.—bee Erhmann. Earthy Mixtures. Feld Spar* 24c Mr. Achard obtained, in the quintal of this ftone, 95 parts, ijlex, 1.7 lime, 1.2 magnefia, o.O copper, SPECIES VI{. Silex, the blue Fluate of Lime, with the Sulphate of Lime and Iron. This Singular combination Sorms the Lapis Lazuli, or Azure Stone. Its colour is of a beautiSul opaque blue, which it preServes in a ftrongheat, and does not Suffer any alteration in this refpea by the contaa of air. The powder of this ftone makes a flight effervefcence with acids : but after calcination it forms a jelly with acids, without exhibiting any previous effervefcence. The powder of this ftone forms the valuable colour known by the name of Ultramarine. The price of this colour is propor- tioned to its intenfity ; and its value is accordingly leafl when it is mixed with pyrites, becaufe thefe bodies diminifh the viva- city of its colour. This ftone affords water by calcination, and when diftilled with the muriate of ammoniack, it forms martial flowers : which. proves, according to Mr. Sage, that its colour is owing to iron. The azure ftone is fufed by a ftrong heat into a whitifh glafs ; and by the affiftance of oxigene it forms a white tranfparent globule inclining to green, without internal bubbles, and not Obedient to the magnet. The fpecifick gravity of the lapis lazuli of Siberia is 29.454. See Briflon. Plates of the lapis Jazuli may be feen upon almoft all richly decorated altars ; it is likewiSe made into tovs. Margraff obtained from this ftone calcareous earth, gypfum, iron, and filex. Mr. Rinmann has difcovered that it contains the fluorick acid. SPECIES VIII. Silex, Alumine, Barytes, and Magnefia. This ftone is known by the names of Feld Spar, Rhomboidal Quartz, Spathum feintillans, Petuntze. "*' it very frequently forms one of the principles of granite, and the cryftals, which are found feparate, arife from the decompo- fition of this primitive rock. The texture c:" feld fn;:r is cxfe, lamellated, and it is leSs har4 jtfnn quartz. 245 Earthy Mixtures. Feld Spar. It Sufes without addition into a whitifh glaSs. I have neverr rtheleSs obServed a very great variety in thp feld Spars, with re- gard to their habitude in the fire. That of Avenue, which is ia the form of whitifh cryftals mixed with quartz, afforded me a tranfparent glafs of extreme hardnefs by the fimple addition of one third of lime : whereas that of Efperon, treated in the fame manner, did not exhibit the Smalleft Sign of fufion. The Specifick gravity of white Seld fpar is 25,946.—See BriSr fbn. Feld fpar exhibits feveral varieties in its form and colour. Moft of the pieces of feld fpar inclofed in granite have a rhomboidal Sorm ; and when this primitive rock becomes decom- posed, the cryftals of feld fpar are detached, and remain con- founded with the rubbifh. The granites of our province, almoft all of them, contain thefe cryftals, fome of which are an inch and an half in diameter. Feld fpar has been found cryftallized in tetrahedral prifms^ terminating in pyramids with four fides. I poffefs fome fpecimens oS Seld Spar oS Auvergne, whoSe tet- rahedral priSms are flattened and terminated by a dihedral Sum- mit. The principal Shades of colour in feld Spar are white, roSe? colour, and chatoyant, or oS changeable colours, The white transparent feld fpar is very rare •, there is a piece in the Royal Cabinet of the Mineral School, which comes from Mount St. Gothar. One hundred parts of white feld fpar contain about fixty-Seven, filex, fourteen alumine, eleven barytes, and eight magnefia. The rofe-eoloured Seld Spar is not very Scarce. Our moun- tains exhibit .much of it. It abounds with iron, which is in the ftate of ochre. .Some experiments have fhewn me that this va- riety is more fufible.than the others. My analySes have even exhibited a larger portion oS magnefia; and its confiftence ap- pears to me to be leSs firm than that of other fpecimens. Feld fpar is compofed of rhomboidal laminae, which give* the property of exhibiting various colours, in a greater or lefs degree. Large pieces of feld fpar have been found on the north- ern coaft of Labrador, worn down by the waters into a round form, of a bluifh grey colour, and exhibiting the moft agreeable change of colours, according to the variation of pofition. The colours are a beautiful celeftial blue, Shaded with green. This ftone is known by the name of Labrador Stone. Granites are frequently found, in which the feld fpar exhibits its changeable colours withut being wrought. Earthy Mixtures. Stales. 24 X CLASS III. Concerning the Mixtures of Stones among each other. Stony Mixtures. Rocks. The mixture of the primitive earths with each other form the ftones we have hitherto treated of; and thefe ftones, united and conneaed together, or as it were joined by a cement, conftitute the numerous clafs of pebbles or ftones, concerning which we fhall proceed to treat. It is evidently feen that the mixture of various ftones has been produced, either by revolutions which have reverfed and confounded the whole furface of countries, or 6y the aaion of waters, which have fucceffively formed the ftrata of rounded flints fpread over the furface of the globe, and! have afterwards depofited in their interftices that earthy matter which has conneaed them together. Thefe mixtures have af- terwards acquired a degree of hardhefs ; and at length appear- ed to form one fingle fubftance. We ffiall eftablifh our genera upon the prefence of fuch ftones as predominate; and the fpecies will be deduced from the vari- ety of ftones mixed with that which determines the genus. GENUS I. Rocks formed by the mixture of Calcareous Stones with other Species. Though the bafis of calcareous ftones enters into the compo- sition of the greater part of lithologick fubftances, we find few rocks which can be ranged in this clafs. SPECIES I'. Carbonate of Lime, and Sulphate of Barytes. Mr. Kirwan obferved compound ftones in Derbyfhire, form- ed of chalk intermixed with nodules of ponderous fpar. SPECIES 11. Carbonate of Lime and Mica. The green marble of Cinolin of Autun is of this kind. It is- compofed of eighty-three parts carbonate of lime, twelve green mica, and one iron.—Journal de Phyfique, t. xii. page ^c. Cal- careous ftones are found in Italy, which exhibit brilliant Specks of mica, and are known by the name of Mafigno. 248 Earthy Mixtures. Stones. SPECIES III. Mixtures of Calcareous and Magnefian Stones. Sulphate of lime, fluate of lime, and carbonate of lime are found mixed with fteatites, ferpentine, talc, amianthus, and af- beftos. Such is, for example, the white marble interfperfed with Spots of fteatites, and defcribed by Cronftadt. SPECIES IV. Calcareous Stones, and Fragments of Quartz Quartz is fometimes found in calcareous cement. Sweden* . and Siberia exhibit feveral marbles which give Sire with the Steel. The calcareous grit, fo eommon in the fouthern part of our kingdom, is of this Species. The Sand is compoSed of fragments of quartzofe flints, rounded and conneaed by a calcareous glu- ten or cement. By digeftion of gritftcme in an acid, the calca- reous cement becomes diffolved, and the proportion which the fand bears to the whole may then be eafily determined. This grit-Stone is feldom hard enough to be ufed in building, or in paving. At Nemours, and at Fontainbleau, this ftone has been found fcryftallized in perfea rhomboids : the cabinets of naturalifts are enriched with fuperb Samples of this kind. Lime-ftone has likewife been found ferving as a cement for feld fpar, fchorl, &c. ; but this is fomewhat rare. Mr. De Sauffure has defcribed a ltone whofe elements are quartz and Spar. Our Shores afford pebbles of hard marble of a light grey col- our, interfperfed with feld Spar and quartz.—See Dorthes. GENUS IT. Compound Stones formed by the Mixture of Barytick Stones with other Stones. As ponderous Spar is of confiderable Scarcity, arid is almoft al- ways found alone, this genus will not be numerous. SPECIES I. Ponderous Spar mi::cd with a fmall quantity of Calcareous Spar. The diocefes of Ahis and of TJzes afforded me this fpecies ; i»nd I ha7C myfelf obferved in the latter rhomboids of calcareous Earthy Mixtures. Stones. 249 fpar, fo well mixed with the lamina; oS ponderous fpar, that it is impoffible to feparate them without deftroying the ftone. It was among the veins of ponderous fpar which are found on the road from Portes to Alais, that I faw this mixture. SPECIES 11. Ponderous Spar and Serpentine. . Mr Kirwan defcribes a fpecies of ferpentine with fpots of barytes. species III. Ponderous Spar and Fluor Spar. The ponderous fpar of Auvergne is mixed with fluor fpar: I have many fpecimens of this. species IV. Ponderous Spar and Indurated Clay. This is the Kros-fteirt of the Germans. The clay which forms the ground is grey, and includes a ponderous fpar of a white colour, which is difpoSed in this clay in the form of veins that might be taken at firft fight for vermiculites, or in general for the remains of fome organized fubftances. This ftone is found at Bochnia in Poland. species v. Poderous Spar and Quartz. I have in my colfeaion feveral fpecimens, in which the pon- derous Spar is diSpoSed in ftars upon a matrix oS the nature of filex. SPECIES VI. Ponderous Spar and Lava. The extina volcanoes oS the dioceSe of Beziers have afforded me lavas, partly decompofed, whoSe SurSace exhibits radii of pon- derous fpar, which, at firft fight, I took to be zeolite. 2...H 25*0 Earthy Mixtures. Stones, genus nr. Rocks or Stones Sormed by the Mixture of Magnefian Stones with other Kinds. species I- Magnefian Stones mixed together. The fame rock often exhibits the various known magnefiarr flones in contaa with each other. Thus we fee the afbeftos pla- ced befide the amianthus, the Serpentine in contaa with the af- beftos, the fteatites in contaa with talc. species ir. Magnefian Stones and Calcareous Stones. The ferpentine has been found fpotted with calcareous fpar,. and gypfum. SPEGIES III* Magnefian Stones and Aluminous Stones. Steatites is frequently mixed with clay. Its fibres are found bedded in an argillaceous fubftance. Steatites and ferpentine are fometimes mixed with fchiftus. SPECIES IV. Magnefian Stones and Siliceous Stones. Serpentine is found mixed with veins of quartz, feld fpar fchorl, &c. ASbeftos and amianthus are often confounded, and fometimes incorporated in quartz and rock-cryftal. Mr. De Sauffure has defcribed a compound ftone, of which the quartz is white, and the fteatites green. At Sterzing in Tyrol, is found a rock formed by fchorl and ferpentine. In the county of Mansfield in Saxony, a rock has been difcov- ered, compofed of jafper and afbeftos. Earthy Mixtures. Stones. 251 GENUS IV. Rocks or Stones formed by the Mixture oS Aluminous Stones with other Species. SPECIES 1. Schiftus and Mica This mixture forms feveral primitive mountains. The mica is Sometimes in plates of a certain thicknefs, but moft common- ly in Small Sragments ; and the ftone affumes a brilliant argen- tine appearance, which renders theSe ftones agreeable to the fighr. In this laft cafe, the Stone is* nearly white, Sonorous, and Splits in- to leaves ; whereas it is blackifh, and lefs hard, when the mica is diSperSed through it in large grains. TheSe kinds of micaceous fchifti do not become fpontaneouf- ly decompofed. They differ effentially from the pyritous fchif- tus, whofe formation appears to be pofteriour to that of the pref- ent fpecies. This micaceous fchiftus is a primitive ftone. It does not in- clude minerals, or at leaft very rarely ; and it is not Spontanea ^oufly decompofed^' SPECIES 11. Schiftus and Garnet. The fchiftus frequently contains garnets, which rife in protu*- berances in its texture, and feparate its ftrata from each other. The garnet is cryftallized, and one would be difpofed to af- firm that this ftone had increafed, and almoft vegetated in the other, which ferves as its covering. It is probable that the gar- net has been enveloped by this pafte of fchiftus ; or that it was formed while the ftone was ftill almoft in the fluid ftate. I found this fchiftus filled with garnets in the bed of the river Bramabiou, in the diocefe of Alais. species 111. Schiftus, Mica, and Quartz mixed in fmall fragments. The Germans call this compound ftone by the name of Gneifs. It deferves to be included among the quartzofe and filiceous flones ; but as it nearly approaches the primitive fchifti we have juft treated of, we ffiall follow the natural method in claffing it here. The texture cf this ftone varies greatly. It fometimes forms a rock in which neither ground nor fibres can be diftinguifhed : in other fpecimens it appears to be divided into filaments twist- ed in a thouSand manners, and it frequently exhibits a lamellated hard texture. 252 Earthy Mixtures. Stones, It is found in large maffes of a greyifh green colour, with its Surface Shining, and polifhed like the Slate ; and it appears to be merely a fine grained granite, the minuteneSs of whofe parts has Suffered them to take the foliated Sorm oS the Schiftus. Mr. Weigleb has analySed that of Friburg. SPECIES IV. Schiftus and Schorl. The mixture of thefe two ftones is common enough. The fchorl is fometimes difperfed in very minute filaments, which give a blackifh tinge to the maSs. Its form is often prifmatick ; in which caSe the fibres of the fchiftus, and the long cryftals of the Schorl, form the prifm by their reunion. A fchiftus has been found iri the Pyrenean mountains, in v/hich the fchorl is Spread from fpace to fpace in the form of oblong bodies, arid equally difperfed over the whole mafs. species v. Clay and Quartz. This constitutes the argillaceous grit-Stone, or the Stone in which fragments of quartz are united together by an argillaceous gluten. Several varieties of grit-ftone may be diftinguifhed. It is often found in irregular, coarfe, and corhpaa maffes, which are made into mill-Hones, or tifed for paving, &c. The magnitude of the fragments Of quartz renders the fur- face more or lefs rugged ; and it is this which renders it proper for certain operations of trituration. When its grain is finer, it is made into grind-Stones. It is by virtue of their quartzous principles that grind-Hones emit fuch numerous fparks, when Struck with the Steel, or when they are moved with rapidity againft any tool of that metal. Argillaceous grit-ftone is fometimes of a fcaly texture : the Cos Turcica of Wallerius, and the ftone ufed for Sharpening Scythes, are of this kind. Fine grit-Stone, compofed of impalpable particles, is known by the name of Tripoli, from the part of Africa whence it firft came. It is now found in Rouergue, in Britanny, Germany, and elfewhere. The porous grit-ftone called Filtcring-dtone, on account of its ufe, is of the fame nature. Quartz is fometimes mixed with mica. Our province contains it in various places. Earthy Mixtures. Stones. 53 The mica is likewife found mixed, I. With feld fpar, according to Ferber and Kirwan. 2. With fchorl, at Mont hykie in Dalecarlia in Sweden, and at Sterzing in Tyrol. 3. With garnets, at Paternion in Carinthia, and at the Car- pathian mountains in Hungary. 4. With garnet and fchorl, at Greyner.—See Muller. 5. With quartz, feld fpar, and fchorl. This compofition forms one of the moft common granites. The mixture of thefe ftones, varied in the proportion of their principles or elements, forms the numerous variety of granites; and feveral colours likewife modify them exceedingly. Genus y. Compound Stones formed by the Mixture and Re-union of Quartzofe 1 Stones with each other. species i. Quartz and Schorl. The quartz is, in general, white in this ftone, and the fchorl of various colours. Some of the paving ftones of London are of this fort, according to Kirwan. ' The fchorl is likewiSe found in cryftals within the quartz. ' SPECIES II. Quartz and Feld Spar. A ftone of this nature was brought me from the neighbour- hood of Avenes. The mountain from which the fpecimen Was detached, contains about one third of quartz. The reft of the rock confifts oS rhomboidal Seld Spar, of no great SirmneSs of texture, and conftantly exhibiting the rhombus in its fraaure. I poffefs a very fine fpecimen of a fimilar rock, which was fent me from Fahlun in Dalecarlia. species in. Girtflone and Garnet. I have received from the mines of TalJard, near Gap in Dau- phiny, girt-ftones with garnets of one or two lines in diameter interfperfed. Thefe garnets are difperfed through the whole mafs, at the diftance cf three or four lines from each other. -S4 Earthy Mixtures, Stones. species iv. Quartz, Feld Spar, and Schorl. This mixture is common, and forms great part of the granites on our globe. The proportion of the elements of this rock vary greatly, but fhe forms of the ftones which compofe it are not lefs variable^ The fchorl is frequently cryftallized in prifms; the feld fpar al- moft always exhibits rhomboidal laminse, on breaking the ftone ; the power of embellifhing their hypotheSes with every ornament which imagination and el- oquence can Surniffi, either as inftruments of Ulufion or enter- tainment, we ought to confider ourfelves indebted to them. For our part, we Shall confine ourSelves to exhibit a few ideas refpeaing the fucceffive decompositions of our planet, and Shall endeavour to avoid every departure from observation and matter cf faa. The flighteft observation Shews us >fhat living -beings are kept up and perpetuated only by Succeffive decompositions and com- binations. A flight view oS the mineral kingdom exhibits the fame'changes ; and our globe, in all its produaions, preSents continual modifications, and a circle of aaivity, which migliL appear incompatible with the apparent inertia of lithologick pro- duas. In order to arrange our ideas with greater regularity, we may confider this globe in two different ftates. We will firft exam- ine the primitive rock which forms the nodule or central part. This appears to contain no germ of life, includes no remains or part of any living being, and from every circumftance appears to have been of primitive formation, anteriour to the creation of animated or vegetating bodies. We Shall purfue the various changes which are daily produced by the deftruaive aaion of fuch agents as alter or modify this fubftance. We Shall then proceed to examine what ftones have been Suc- ceffively placed upon this, and what are the decompositions tq which theSe Secondary rocks have been fubjeaed. Geological Obfervations. 2 are formed in clays which contain their component parts. * This is the firft and the laft fuppofition in which I Shall indulge my- felf. It is a conjecture, however, which is indifferent with refpect to the bafis of the fubject itfelf; fince it relates only to an hypothefis refpecting the manner in which a rock might be formed that at prefent exifts, and whofe decompositions alone can form the fubject of our obfervations. 2"4 Geological Obfervations. It may eafily be conceived that the laws of gravitation mrift have influenced the arrangement and difpofition of the produas. The moft grofs and heavy bodies muft have fallen, and the light- eSt ^nd moft attenuated fubftances muft have arranged them- felves on the furSace oS the Soregoing : and this it is which con- stitutes the primitive Schilti, the gneis, the rocks of mica, Sec. which commonly repofe upon maffes of coarfe-grarned granite. The difpofition oS the fine-grained granite in ftrata or beds, appears to me to depend on this pofition, and the fihenefs or tenuity oS its parts. Being placed iri immediate contaa with water, this fluid muft naturally have influenced the arrangement which it prefents to us; and the elements of this rock being fubjeaed to the effea of waves, and the aaion of currents, muft have Sormed Strata'. The rocks oS granite being once eftablifhed as the nucleus of our globe, we may, from the analysis of its conftituent principles, and by attending to the aaion of the various agents capable of altering it, follow the degradations to which it has been fubjea- ed, ftep by ftep. Water is the principal agent whofe effeas we Shall examine. This fluid, colfeaed in the cavity oS the ocean, is carried by the winds to the tops of the moll elevated mountains, where it is precipitated in rain, and forms torrents, which return with various degrees of rapidity into the common refervoir. This uninterrupted motion and fall muft gradually attenuate and wear away the hardeft rocks, and carry their pulverulent parts to diftances more or lefs confiderable. The adtion of the air, and varying temperatures of the atmofphere, facilitate the attenuation and the deftruaion of thefe rocks. Heat dries their furface and renders it more acceffible and more penetrable to the water which fucceeds; cold divides them, by freezing the water which has entered into their texture ; the air itfelf affords1 the carbonick acid, which attacks the lime-ftone, and caufes it to effloreSee ; the oxigene unites to the iron, and calcines it; info- much that this concurrence of caufes favours the difunion of principles ; and confequently the aaion of water, which clears the furface, carries away the produas of decompofition, and: makes preparation for a Succeeding procefs of the fame nature. The firft effea of the rain is therefore to deprefs the moun- tains. But the ftones which compofe them muft refift in pro- portion to their hardnefs ; and we ought not to be Surprised when we obServe peaks which have braved the deftruaive ac- tion of time, and ftill remain to atteft the primitive Jevel of the mountains which have disappeared. The primitive rocks, alike ir.acceffible to the injury of ages as lo the animated be- Geological Obfervations. 265 ings which cover lefs elevated mountains with their remains, may be confidered as the fource or origin of rivers and flreams. The water which falls on their fummits, flows down in torrents by their lateral furfaces. In its courfe it wears away the foil upon which it inceffantly aas. It hollows out a bed, of a depth proportioned to the rapidity of its courfe, the quantity of its wa- ters, and the hardnefs of the rock ovejprwhicli it flows ; at the fame time that it carries along with it portions and fragments of fuch ftones as it loofens in its courfe. Thefe ftones, rolled along by the water, muft ftrike together, and break off their projeaing angles : a proceSs that muft quickly have afforded thofe rounded flints which Sorm the peb- bles of rivers. Thefe pebbles are found to diminifh in Size, in proportion to the diftance from the mountain which affords them ; and it is to this caufe that Mr. Dorthes has referred the difproportionate magnitude of the pebbles which form our an- cient worn ftones, when compared with thofe of modern date : for the fea extending itfelf formerly much more inland, in the direaion of the Rhone, the ftones which it received from the rivers, and threw back again upon the fhores, had not run through fo long a fpace in their beds as thofe which they at pre- fent pafs over. Thus it is that the remains of the Alps, carried along by the Rhone, have fucceffively covered the vaft interval comprifed between the mountains of Dauphiny and Viva- rais ; and are carried into our feas which depofite them in Srnall pebbles on the Shore. The pulverulent remains of mountains, or the powder which refults from the rounding of thefe flints, are carried along with greater facility than the flints themfelves : they float for a long time in the water, whofe tranfparence they impair ; and when thefe fame waters are lefs agitated, and their courfe becomes Slackened, they are depofited in a fine and light pafte, forming beds more or lefs thick, and of the fame nature as that of the rocks to which they owe their origin. Thefe ftrata gradually become drier by the agglutinatiomof their principles ; they be- come confiftent, acquire hardnefs and form filiceous clays, filex, petrofilex, and all the numerous clafs of pebbles which are found difperfed in ftrata, or in banks, on the ancient beds of rivers. Mr. Pallas has obferved the transition of clay to the ftate of filex in the brook of Sunghir, near Wolodimir. Mr. J. W. Baumer has likewife obferved it in Upper Heffe. The mud is much more frequently depofited in the interftices left between the rounded flints themfelves, which intervals it fills, and there forms a true cement that becomes hard, and con- stitutes the compound ftones known by the name of puddine- 2...K * * z66 Geological Obfervations, flones and grit-ftones ; for thefe two kinds of ftone do not ap- pear to me to differ but in the coarfenefs of the grain which forms; them, and the cement which' conneas them together. We Sometimes obServe the granite Spontaneoufly decompofed. The texture of the ftones which Sorm it has been deftroyed ; the principles or component parts are diSunited and Separated, and they are gradually parried away by the waters. I have ob- ferved near Mende, towards Caftlenouvel, the mofl beautiful ka- olin on the Surface oS a granite, in a Slate of decompofition ; and this fame rock is decompofed in Several other parts of our prov- ince. It appeared tome that the feld fpar was particularly fub- jea to be altered the firft. Moft filiceous ftones, formed by the deposition of fluvia- tile wafers, and hardened by the lapfe of time, are eafily fub- jeaed to a Second decompofition. Iron is the principal agent of theSe Secondary alterations ; and its calcination determined by air or water, produces a' diSunion of principles. Nature may be obferved in this- procefsi by an attentive examination of fuch alterations as gun flints, varoilites, porphyries, jafpers, and the like are fubjeaed to. The decompofition of flints,calcedbnies, agates, and generally all ftohes of this kind which poffeSs a certain degree of tranfpar- ence, appears to me to be referable to the volatilization of the water which forms one of their principles, and is the caufe of their transparency. TheSe Stones" may be confidered as commencements of cryf- tallization ; and, when the water is diffipated, they effloreSce af- ter the manner oS certain neutral Salts. Hence it ariSes that the decompofition is announced by opacity, a white Colour, lofs of confiftence and hardneSs ; and terminates by forming a very attenuated powder, fometinles of extreme whitenefs. It is this decompofition, more particularly, which Sorms clays. There are flints wlioSe alterations form efferveScent marles. TheSe do not appear to me to be of the nature of primitive rocks ; they have the fame origin as the calcareous ftones, from - which they differ only in confequence of a very confiderable proportion of clay. The ftones which we fo abundantly find of this nature around us, among calcareous decompositions, may be confidered as of this kind. Water filtrating through mountains of primitive rock, fre- quently carries along with it very minutely divided particle;; of quartz ; and proceeds to form by depofition, ftalaaites, agates, rock cryftal, &c. Thefe quartzofe ftalaaites differently coloured, arc of a form- ation considerably analagous to that- of calcareous alab?.Sters ^ Geological Obfervations. 26"j and we perceive no other difference between them than that of their conftituent parts. III. Thus Sar we have exhibited, in a few words, the princi- pal changes, and various modifications, to which the primi- tive rocks have been Subjeaed. We have not yet obServed ei- ther germination orliSe ; and the metals, Sulphur, and bitumens, have not hitherto prefented themfelves to our observation. Their Sormation appears to be pofteriour to the exiftence oS this primitive globe ; and the alterations and decompositions which now remain to be enquired into, appear to be produced by the clafs oS living or organized beings. On the one hand, we behold the numerous claSs of Shell ani- mals, which caufe .the ftony mafs of our .globe ,to increafe by their remains. The fpoils of thefe creatures, long agitated and driven about by the waves, and more or lefs altered by collision, form thofe ftrata and banks of lime-ftone, in which we very of- ten perceive impreffions of thofe Shells to which they owe their .origin. On the other hand, we obferve a numerous quantity of veg- etables that grow and perifh in the fea ; and thefe plants like- wife, depofited and heaped together by the currents, form ftrata, which are decompofed, lofe their organization, and leave all the principles of the vegetable confounded with the earthy princi- ple. It is to this fource that the origin of pit-coal, and Second- ary fchiftus, is ufually attributed ; and this theory is eftablifhed on the exiftence of the texture of decompofed vegetables very ufually feen in fchifti and coal; and likewife on the prefence of fhells and fifli in moft of thefe produas. It appears to me that the formation of pyrites ought to be at- tributed to the decompofition of vegetables: It exifts in great- er or lefs abundance in all fchifti and coal. I have found a wooden ffiovel buried in the -depofitions of the river De Ceze, converted into jet and pyrites. The decompofition of animal Subftances may be added to this caufe; and it appears to me to be a confirmation of thefe ideas, that we find many fhells paffed to the ftate of pyrites. Not only the marine vegetables form confiderable ftrata by their decompofition; but the remains of thofe which grow on the furface of the globe ought to be confidered among the caufes or agents which concur in producing changes upon that furface. We ffiall feparately confider how much is owing to each oi thefe caufes ; and ffiall follow the effeas of each, asif that caufe alone were employed in modifying and altering our planet. 1. The calcareous mountains are conftantly placed upon the furface c i the primitive mountains; aad though a few foluary 268 Geological Obfervations. obfervations prefent a contrary order, we ought to confider this inverfion and derangement as produced by Shocks which have changed the primitive difpofition. I muft obServe alfo that the diforder is Sometimes merely apparent; and that fome natural- ifts oS little information have deScribed calcareous mountains as inclining beneath the granite, becauSe this laft pierces, as it were, through the envelope, riSes to a greater height, and leaves at its feet, almoft beneath it, the calcareous remains depofited at its baSe. Sometimes even the lime-ftone fills to a very great depth the crevices or cleSts formed in the granite. I have feen in Gevau- dan, towards Florae, a profound cavity in the granite filled with calcareous ftone. This' vein is known to poffeSs a depth of more than one hundred and fifty toifes, with a diameter of about two or three. It likewife happens frequently enough that fuch waters as are loaded with the remains of the primitive granite, heap them to- gether, and form fecondary granites, which may exift above the calcareous ftone. Thefe calcareous mountains are decompofed by the combined aaion of air and water ; and the produa of their decompofition Sometimes forms chalk or marie. The Iightnefs of this earth renders it eafy to be transported by water ; and this fluid, which does not poffeSs the property of holding it in folution, Soon depofites it in the form of gurhs, alabafters, ftalaaites, &c. Spars owe their formation to no other caufe. Their cryftallization is pofteriour to the origin of calca- reous mountains. Waters wear down and carry away calcareous mountains with greater eafe than the primitive mountains ; their remains being very light, are rolled along, and more or lefs worn. The frag- ments of thefe rocks are fometimes conneaed by a gluten or. cement of^he fame nature ; from which procefs calcareous grit and breccias arife. Thefe calcareous remains formerly depofit- ed themfelves upon the quartzofe fand ; and the union of prim- itive matter and fecondary produas, gives rife to a rock of a mix- ed nature, which is common to our province. 2. The mountains of fecondary fchiftus frequently exhibit to us a pure mixture of earthy principles, without the fmalleft vef- tige of bitumen. Thefe rocks afford, by analyfis, filex, alumine, magnefia, lime in the ftate of carbonate, and iron; principles which are more or lefs united, and confequently acceffible in various degrees to the aaions of fuch agents as deftroy the rocks hitherto treated of. Geological Obfervations. 269 Thefe fame principles when difunited, and carried away by waters, give riSe to a great part oS the ftones which we have com- prised in the magnefian genus. The fame elements, worn down by the waters, and depofited under circumftances proper to fa- cilitate cryftallization Sorm the Schorls, tourmaline, garnets, &c. We do not pretend by this to exclude and absolutely rejea the Syftem of Such naturalifts as attribute the Sormation oS mag- nefia ftones to the decompofition of the primitive rocks. But we think that this formation cannot be objeaed to for feveral of them, more efpecially fuch as contain magnefia in the greateft abundance. It frequently happens that the fecondary fchifti are interfperf- ed with pyrites ; and, in this cafe, the fimple contaa of air and water facilitates their decompofition. Sulphurick acid is thus formed, which combines with the various conftituent principles of the ftone ; whence refult the fulphates of iron, of magnefia, of alumine, and of lime, which efflorefce at the furface, and remain confounded together. Schifti oS this nature are wrought in moft places where alum works have been eftablifhed ; and the moft laborious part oS this undertaking confifts in Separating the Sulphates of iron, of lime, and of magnefia from each other, which are mixed together. Sometimes the magnefia is fo abun- dant that its fulphate predominates : I have feen mountains of fchiftus of this nature. The fulphate of lime being very fpar- ingly foluble in water, is carried away by that liquid, and de- pofited to form gypfum ; while the other more foluble falts re- maining fufpended, form vitriolick mineral waters. The pyritous fchifti are frequently impregnated with bitumen, and the proportions conftitute the various qualities of pit-coal. It appears to me that we may lay it down as an inconteftible principle, that the pyrites is abundant in proportion as the bitu- minous principle is more Scarce. Hence it arifes, that coals of a bad quality are the moft fulphureous, and deftroy metallick veffels by converting them into pyrites. The Socus oS volcanoes ap- pears to be Sormed by a Schiftus of this nature; and in the anal- yfes of the ftony matters which are ejeaed we find the fame principles as thofe which conftitute this fchiftus. We ought not therefore to be much furprized at finding fchorls among vol- canick produas ; and ftill lefs at obferving that fubterranean fires throw fulphurick falts, fulphur, and other analogous pro- duas out of the entrails of the earth. 3. The remains of terreftrial vegetables exhibit a mixture of primitive earths more or lefs coloured by iron : we may there- fore confider thefe as a matrix in which the feeds of all ftony combinations are difperfed. The earthy principles affort them- 2 7° Geological Obfervations. Selves according to tfie laws oS their affinities ; and Sorm cryftal? of Spar, oS plafter, and even the rock crystals, according to all appearance : for we find ochreous earths in which theSe cryftals are abundantly diSperSed ; we See them Sormed almoft under our eyes. I have Srequently obServed indurated ochres Sull of thefe cryftals terminating in two pyramids. The ochreous earths appear to me to deServe the greateft at- tention of naturalifts. They conftitute* one of the moft fertile means of aaion which nature employs ; and it is even in earths nearly fimilar to thefe that fhe elaborates the diamond, in the kingdoms of Golconda and Vifapour. If it were allowable to indulge in a fiaion purely poetical, we might affirm that the el- ement of fire, fo far from being loft by the difperfion of the com- buftible principles of vegetables, becomes purified to form this precious ftone fo eminently combuftible ; that nature has been defirous of proving that the terms Deftruaion and Death are relative only to .theimperfeaion of our fenfe-; ; and that She is never more fruitful than when we fuppofe her to be at the mo- ment of extinaion. The fpoils of animals which live on the furface of the globe, are entitled to fome confederation among the number of caufes which we affign to explain the various changes our planet is fubjeaed to. We find bones in a ftate of confiderable preferva- tion in certain places ; we can even frequently enough diftin- guifh the fpecies of the animals to which they have belonged. From indications of this fort it is that fome writers have en- deavoured to explain the difappearance of certain fpecies ; and to draw conclusions Srom thence, either that our planet is per- ceptibly cooled, or that ? Senfible change has .taken place in the pofition oS the axis oS the earth. The phofphorick Salts and phoSphorus which have been Sound, in our time, in combination with lead, iron, &c. prove that, in proportion as the principle are diSengaged by animal decomposition, they combine with oth- er bodies, and Sorm the nitrick acid, the alkalis, and in general the numerous kinds oS nitrous Salts. PART THE THIRD CONCERNING METALLICK SUBSTANCES. INTRODUCTION. -M.ETALLICK fubftances are diftinguifhed from all the other produaions of our globe, by an abfolute opacity, a riiuch greater fpecifick gravity than that of any other fubftance, and a degree of brilliancy peculiar to bodies of this clafs. The multiplicity of ufes to which metals are applied in the arts, and in medicine, as well as the place which they occupy in the natural hiftory of our planet, render the ftudy of them both interefting and neceffary. i. One of the diftinaive charaaers of metals is their opacity. The moft opaque ftone, divided into very thin laminae, becomes tranfparent; whereas the thinned plate of metal preferves the fame opacity as the mafs itfelf.* This truly characteriftick pro- perty has induced artifts to employ metals to reffea the images ofobjeas. A thin covering of tin and mercury fixed on the Surface of a glafs, forms a mirror or looking-glafs ; and well poliShed Steel conftitutes the mirrors of telefeopesf The hard- nefs of a metal contributes Angularly to facilitate the reffeaion of objeas, as it renders it capable of taking a very fine polifh, * Gold excepted : which, when beaten into leaf of about the two hun- dred and eighty thoufandth part of an inch in thicknefs, tranfmits light of a beautiful green colour. It is highly probable that other metals would become tranfparent if they could be mechanically divided, or beaten out into laminse of futftcient thinnefs, or if oralis had Sufficient motives to attempt it. See Newton on Light and Colours, for the proofs on which he grounds his general inference—that all bodies are tranfparent when fufhdentlv di- vided. T. f I do not find that Steel has ever been in general ufe for reflecting tel- efcopes, though it has doubtlefs been tried among the many expe- riments made for the improvement of thefe inftruments. A kind of bell-:netal, confuting of one third tin, and two thirds copper, is com- monly employed for this purpofe : the addition of about a fiftieth part of arfenick Singularly contributes re the clofenefs of its grain. On thisfubject confult the Treatifc of Mr. Edwards, annexed to the Nacfcai Almanack fen; 87. T. ~72 Genera! Properties of but its colour muft neceffarily concur to render it perfea * for thefe tinges caufe it to abforb a greater or lefs quantity of the rays. The great defea of metallick mirrors is, that their Surface becomes tarnifhed by the inevitable alteration which the aaion of the air and moiflure muft produce. 2. The relative weight is likewife a charaaer by which we may diftinguiffi a metallick fubftance. A cubick foot (French) of marble weighs 190 pounds (livres); a cubick foot of tin weighs 510; and a cubick foot oS gold 1348. The metals, in general, likewiSe poffeSs the facility of being extended and flattened when ftruck, or fubjeaed to a ftrong and gradual preffure : this property is known by the name of Duaility. All the metals do not poffeSs this quality ; but thofe which poffeSs the metallick qualities moft eminently, exhibit this likewiSe. We may diftinguifh three ftates of ductility relative to the manner in which it is modified by various known procef- fes. 1. Duaility under the hammer. 2. Duaility through the plate oS the wire-drawer. 3. Duaility between the lami- nating rollers. Metals duaile under the hammer preSent themfelves in the following order : Gold, Silver, Copper, Iron, Tin, and Lead. Metals duaile through the wire-drawer's plate form the fol- lowing feries : Gold, Iron, Copper, Silver, Tin, and Lead.—As, in the operation of wire-drawing, the metal is ftrongly drawn, to caufe it to pafs through holes of various diameters, and to re- duce it into threads, the metals do not refift this prodigious ex- tenfion but in proportion to their greater or lefs tenacity. Mr. De Fourcroy has therefore diftinguifhed this duaility from the foregoing, by attributing it merely to the tenacity of the metals. There are fome metals which are not duaile either under the hammer or through the wire-drawer's plate, but become very confiderably fo when an equal and gradual preffure is applied. Zinck is of this nature. Mr. Sage has reduced it into very thin and very flexible leaves, by pafling it between the laminating cy- linders. Heat affifts the duaility of all metals, by feparating their in- tegrant parts, and forming fpaces or interftices which permit the compreffed molecules to flatten and extend themfelves. This cir- cumftance has induced artifts to avail themfelves of the affiftance of heat in the working of metals. Without this precaution they would either become hard, or crack ; becaufe the particles, being too near each other would be no longer capable of giving way under the hammer. The duaility of metals permits us to faffiion them as we think fir; and it is upon this admirable property that almoft all the Metallick Sub/lances. i 73 £f is are founded which relate to the working of metals. With- out this property, metallick bodies would confift either of ffiape- leSs maffes, or large pieces Of Such figures as catling might pro- duce. But we Should be deprived of the number of various ob- jeas which the arts have fucceflively afforded to Supply our wants cr luxuries. l Nature very Seldom preSents us with metals poffeffed of the degrees of perfeaion here enumerated. She has concealed them in the bowels of the earth, combined with various fubftances; which, by mafking or changing the metallick properties, have left to the induftry of man the laborious tafk of extraaing them, clearing them of their original combinations, and giving them the valuable qualities which are peculiar to metals. The metals, thus buried and concealed, form ores. Thefe ores ufually exift in cleSts or crevices oS rocks, which are diftinguiffied by the name oS Veins. TheSe veins are more or leSs inclined to the horizon; and the degrees oS inclination have cauSed them lobe diftinguiffied by the names oS direa, oblique, inclined, or level veins, according to the angle they make with the horizon. The part oS the rock which refts upon the SuperioUt part of the vein, is called the Roof; and that part upon which the vein itfelf refts, is called the Bed of the vein. Thefe veins are of various breadths, and are accordingly diftinguiffied by the names of Slips of Veins. They poffefs a greater or lefs degree of continuity, according to which they are diftinguiffied by the names of continued or broken veins ; and when the ore is found in Spherical parts or maffes, Srom Space to Space, theSe maffes are called Bellies or Stock-works. A vein which does not penetrate to a confiderabfe depth in the earth, is called by us Goureur de Gazott. The characters from which mineralogifts pretend to affert the exiftence of an ore in the bowels of the earth, are all equiv- ocal and fufpicious. The favage afpea of a mountain, the na- ture of the plants which grow upon it, the exhalations which arife from the earth, all afford charaaers too doubtful for a rea- sonable man to rifle his fortune upon fuch indications alone. The dipping wand, or divining rod, is the fruit of fuperftition and ignorance; and the ridicule which has been fucceflively thrown upon this clafs of impoftors, has diminished their num- ber ; at the fame time that the numerous dupes of this clafs of men have rendered their fucceffors more prudent The nature of the ftones which compofe a mountain is capa- ble of furnifhing fome indications. We know, for example, that ores are feldom found in granite, an 1 the other primitive mountains; we know likewife that mountains of too modern a 2...L r/ 4 Mines and Metallick Ores. formation contain them very rarely ; and we find them only ic fecondary mountains, in which the fchiftus and ancient calcare- ous ftone are void of aft impreffions of Shells. The prefence of ponderous fpar, forming a Stratum or vein at the Surface of the earth; has been confidered by many mineral- ogifls asa very good indication. It appears to me even that this- ftoue is the Same which Becher has Spbken of in his works, un- der the name oS Vitrifiable Earth, which he confidered as a prin- ciple of metals; and that it has been very improperly taken for quartz by his readers. The vitrifiable ftone of Becher—" lapidis fpecies quae in igne fluit, et fluens vitrum exhibet,"—and elfewhere, f( tranSparens enim nonnihti eft, albus, et quafi, argenteis foliis interSperSus,- ad ignem Sacile liquabttis,"—was confidered by him as a certain indication of the preSeme of ores, as appears by the following paffage : " Sine quo lapide, nu'la mirjera bona eft, nee fertilateni promittit; adeo enim ifte lapis mineris neceflarius eft, ut vel nude, et fine ullo metallo, in rriontibus exiftens, infallible fignum futuri metalli fit; quod, hoc figno freti, non fine magnis, mter- dum fumptibus, quaerunt minerarum indagatores ; hanc ergo five terram five lapidem, non fine pregnatibus caufis, pro princi- pio primo omnium metallorum, minerarum, et lapidum ac gem- raarum, ftatuimus et agnoScimas ; certis freti experimentis, ut in fequentibus demonftrabimris, quibus evincere poffumus prse- fatam terram aau in metallis et mineralibus omnibus, nee non> lapidibus et gemmis, exiftere,eorumque mixtum utbafim et Sun- damentum ingredi ; unde ea hypoftafin Suam, oppofitatem, diar phaneitatem, et fluxum nanciScuntur.....Usee ergo terra non rnodo. cum preSens adeft inSailibile fignum affuturi metalli eft, Sed et abSens idem fignum exiftit, defuturi nempe metalli.....de- fectus hujus terrce proxima et frequentiffima caufa flerilium minerarum exiftit.... lapis de quo egimus, non medo ut matrix fed ut ingrediens et principium." When we poffefs indications of the exiftence of an ore in any place, we may ufe the borer, to confirm or deftroy thefe Sus- picions, at a fmall expenfe. It frequently happens that the veins are naked or uncovered ; the mixture of ftones and metals forms a kind of cement which refills the deftruaive aaion of time longer than the reft of the mountain; and as thefe parts of rocks conneaed by a metallick cement, prefent a ftronger refiftance to the aaion of waters, which inceflantly corrode and diminish mountains, and carry; away their parts into the fea, we frequently obferve the vein', projeaing on the fides «f the mountains incrufted with Some flight metallick imprclfion altered by the lapfe cS tim?. The Affaying of Ores. 275 Before we proceed to treat of metallick works in the large aluminiform oaahedrons. Arfenick is fometimes found native ; and it is met with in, flalaaites, or in protuberant depofitions formed of layers more or lefs diftina and concentrick, which are feparable from each, other like the coats of an onion, or the lamina? of fhells, from, which it has obtained the name of teftaceous arSenick. In other inftances the maffes are formed of very fmall fcales; which renders the Surface of the fpecimen Sometimes granulated, and fometimes Sull of fmall cavities : it is then called fcaly arfenick. Arfenick is alfo found in friable maffes, poffeffing Scarcely any confiftence. In theSe various Sorms we receive it from Bohemia, Hungary, Saxony, Saint Marie aux Mines, &c. Arfenick is volatilized by an heat of about 144 degrees of Reaumur. In order to fet fire to this metal, it muft be thrown into a crucible ftrongly ignited; and then it exhibits a blue flame, and riSes in the form of a white oxide. If it be Sublimed by a gentle heat, it cryftallizes in trihedral pyramids or in oaahedrons. ArSenick is not Soluble in water. Its fpecifick gravity is 57633, according to Briffon. Its Sraaure refembles that of fteel, but it eafily tarnishes. ArSenick appears to exift in the metallick ftate in its combi- nations with cobalt in the teftaceous cobalt ore, or with iron in miSpickel, according to the observation of Bergmann. Properties cf Arfenick. 2S3 ArSenick unites by Sufion with moft oS the metals ; but thoSe jwhich were duaile before this addition, become brittle after- -wards. Thofe which are of difficult fufion alone flow more -eafily by heat with the addition of arSenick, and thoSe which are very Sufible become refraaory by the Same addition. The yellow or red metals become white with this alloy. ArSenick is oSten combined with metals in various ores, and is diSengaged from them by calcination. In various mine works, long winding chimneys are conftruaed, through which the arfenical vapours paSs, and in which they attach themSelves. The cruft which is Sormed in proceSs oS time againft the intern- al Surface of thefe chimneys is taken away, and is the fubftance •met with in commerce under thename of arfenick. The co- 4>alt ores of Saxony, which are torrefied to feparate this femi- metal, afford almoft the whole of what is fold. This oxide of Arfenick is fometimes native, and has been found in Saxony and -Bohemia. It is very abundant in fuch places as are Situated in the vicinity oS Subterranean fires, fuch as the SolSatara. It is oSten Sound cryftallized in oaahedrons, according to Mr. Sage. The oxide is lefs volatile than the metal itfelf; and, as we have before obferved, it emits a very evident fmell of garlick. If it be fublimed by a Strong fire in clofed veffels, it becomes tranfparent like glafs; but its furface is foon rendered opaque again by expofure to air. It is not rare to find arfenical glafs in the arfenick of commerce : it is yellowish, and foon lofes its •tranfparency by expofure to air. This glafs is fometimes found •native in the cobalt mines, and among volcanick produas. Eighty parts of diftilled water, at the temperature of twelve degrees, are required to diffolve one part of the oxide of arSen- ick ; but,fifteen are fufficient at the boiling heat. 'One part of arfenick is foluble in between feventy and eighty parts of alcohol at the boiling heat. The oxide of arfenick partakes therefore of the properties of faline fubftances, and differs from the other metallick oxides-r- ■1. Becaufe it is perfeaiy foluble in water. 2. Becaufe the oth- ~er metallick oxides are without fmell, and fixed in the fire. 3. JBecaufe thofe oxides do not contraa any union with metals. On the other hand it refembles the metaliick oxides—1. In becoming converted into a metallick glafs by a Strong heat. 2. Jn forming an opaque infoluble fubftance, poffeffing the metal- lick brilliancy when deprived of oxigene. The oxide of arfenick is capable of combining with fulphur; and the reSult is either orpiment or realgar, according to the ;manner of operating. 284 Realgar. Orpiment. Moft chemifts have a notion that the realgar contains more fulphur than the orpiment; and they have preScribed different proportions to form thefe two fubftances. But it has been prov- ed by Mr. Bucquet, that this difference of colour arifes onlyf from the manner of applying the fire ; nothing more being ne- ceffary to convert orpiment into realgar, than the expofing it to a, ftrong heat: and with the Same mixture we may at pleaSure ob- tain either of thefe produas, according to the manner of apply- ing the heat. Orpiment and realgar are found native in certain places; Lin- xiseus, Wallerius, Bergmann, and Cronftedt have deScribed them. Cryftals of realgar are found in Solfatara near Naples, accord- ing to Ferber; in the mines of Nagyag in Trailfylvania (fee Forfter'sCatalogue;) in the mines of Felfobanya in Upper Hun- gary; in thofe of Joachimftal in Bohemia, and of fylarienburg in Saxony. Realgar is common in China ; it is made into vafes, pagods,. find other ornamental works. The Indians make ufe of theSe.- Veffels to procure a purgative medicine; for this purpofe they leave vinegar or lemon juice for feyeral hours in the veffel, and, afterwards drink it. Realgar is commonly found in the waters of volcanoes. I have. almoft always obferved it in compreffed hexahedral prifms, ter- minating in two tetrahedral Summits. Orpiment is lefs Scarce than the realgar. It almoft always ac- companies this fubftance; but the orpiment of commerce comes to us from various countries up the Levant, in irregular maffes, folid or lamellated, and of a beautiful orange yellow. The! Baron de Born informs us that it is met with, in polyhedral cryf- tals, in a bluifh clay near Newfol in Hungary. Lime and the alkalis decompofe theSe two fubftances, and difengage the oxide of arfenick. The acids and the alkalis exhibit interefting phenomena with arfenick. The fulphurick acid, when boiled on the oxide of arfenick, . attacks and diffolves it ; but this oxide is precipitated by cool- ing. If the whole of the acid be diffipated by a ftrong heat, the arfenical acid remains behind. The nitrick acid, affifted by heat, diffolves the oxide of arfen- ick, and forms a deliqueScent fait, of which we ffiall preSently treat. The muriatick acid attacks arSenick very Seebly. Meffrs. JJayen and Charlard found its aaion very weak whether heatetj p| copied. Sublimed Muriate, and Oxide of Arfenick. 285 In order to Sorm the Sublimed muriate of arfenick, or butter pf arfenick, equal parts oS orpiment and corrofive Sublimate of mercury are mixed together. The mixture is diftilled by a gen- tle heat ; and the receiver is Sound to contain a blaekiffi corro- five liquor, which Sorms the Sublimed muriate oS arSenick. Cin- nabar comes over iS the heat be increaSed, according to the ob- servation of Mr. Sage. If pure pot-affi be boiled on the oxide of arfenick, the alkali becomes brown, gradually thickens, and at laft forms a hard brittle mafs. This arfenical fait of Mr. Macquer is deliqueS- cent. It is Soluble in water, which lets Sail brown flocks. It*s decomposed by fire, and the arSenick efcapes. Acids deprive i% pf its alkali, &c. Soda exhibits phenomena nearly fimilar with this oxide ; and Mr. Matquer even affirms that he obtained this Salt in cryftals. I have proved that ammoniack diffolves the oxide oS arSenick by heat ; and I have Several times obtained cryftals oS arSenick by Spontaneous evaporation. I am even of opinio* that the al- kali is decompofed in thefe circumftances, that the nitrogene is diffipated, while the hydrogene unites with the oxigene of the oxide, and forms water. The oxide of arfenick haftens the vitrification of all the earths; but the glafles into which it enters as a component part, have the property of eafily becoming tarnifhed. Equal parts ofnjtre and oxide of arfenick, diftilled in a retort, afford a very red and almoft incoercible nitrick acid. Stahl and Kunckel obtained it by a proceSs nearly fimilar. Macquer hav- ing dumed this work, carefully examined the refidue in the re- tort, and found that it was a Salt Soluble in water, capable of cryftallizing in tetrahedral priSms terminated by four-fided pyra- mids, unalterable in the air, fufible by a moderate heat, but with- out becoming alkalized. Mr. Macquer called it the neutral ar- fenical fait : he fuppofed that no acid could decompofe it. But Mr. Pelletier proved that the fulphurick, when diftilled with it, ffiffengaged its acid. The arfeniate of foda. differs little from the arfeniate of pot- afh. Mr. Pelletier obtained this Salt cryftallized in hexahedral priSms, terminated by planes perpendicular to their axes. By theSe Several experiments, Mr. Macquer had Shewn that arSenick anSwered the purpoSe of an acid in theSe combinations. There remained only one Step therefore to be made, to prove that it was really metamorphoSed into an acid in theSe Several ope- rations ; and it is to the celebrated Scheele that we are indebt- ed Sor this diScovery. His capital experiments upon manganeSe naturally led him to it. :.86 Acid.of Arfenick. He has given us two proceffes to obtain this arfenical acid ; the firft by means of the oxigenated muriatick acid, and the oth- er by the nitrick acid. Thefe acids are diftilled from the oxide of arfenick : the muriatick acid abandons its oxigene to the ox- ide of arfenick, and reSumes the charaaers of the ordinary mu- riatick acid. The nitrick acid is itfelf decompofed ; and one of its principles is diffipated, while the other is fixed and com- bines with the arfenical oxide. This acid is at prefent obtained by diftilling fix parts of nitrick acid from one of oxide of arfenick. Mr. Pelletier likewife propoSes to decompofe the nitrate of ammoniack by the oxide of arfenick. The refidue in the retort is the arSeniate oS ammoniack, from which the alkali may be driven by a Sire long kept up. The refidue is a vitreous mafs, ftrongly attraaing humidity, and falling into deliquium. It is the pure arfenical acid. Mr. Pelletier has likewiSe decompofed the neutral arfenical fair,; by mixing it with half a part of oil of vitriol, and urging the fire to fuch a degree as to ignite the veffels. The refidue at the bottom of the retort is a white maSs, which attraas humidity, and is the arSenical acid. A white powder is obServable, which is found to be the fulphate oS pot-afh or of foda, accordingly as the arfenical Salt has Soda or pot-afli for its bafis. From the various proceffes made uSe of to form the arSenicil acid, it is evident that this Subftance is nothing but the arfenical oxide, Saturated with the oxigene which it takes from the various bodies digefled upon it. The nitrick acid, or the nitrates uSed •for this purpoSe, are decompoSed ; the nitrous gas paffes over very abundantly, and the oxigene remains mixed and united with the oxide of arfenick. This acid poffeffes the concrete form ; but it attraas the hu- tnidity of the air, and becomes reSolved into a fluid. It is fixed in the fire ; but if it be heated in contaa with z .coaly fubftance, it is decompofed, and the oxide exhales in the form oS Sumes. It is reduced into arSenick, according to Mr. Pellettier, by pafling hydrogenous gas through it. At the temperature of twelve degrees of the thermometer of Reaumur, this acid requires only two thirds oS its weight of wa- ter to diffolve it; whereas one part of the oxide of arfenick re- quires twenty-four of water to diffolve it at the fame tempera*- ture. This acid, when diffolved in water may be again concentrated, ^nd carried to the ftate of a tranfparent glafs without any alter- ation,; for it is not by this treatment deprived of its power of at* traaing humidity from the air. Counterpoifon againft Arfenick. 287 When it is in this ftate of concentration, it aas ftrongly on, the crucible, and diffolves the alumine, according to Mr. Ber- thollet's experiments. The arfenical acid, faturated with ammoniack, and duly evap- orated, forms a fait cryftallized in rhomboids which, when urg- ed by heat, lofes its water of cryftallization, next its alkali, and is refolved into a vitreous mafs. Barytes and magnefia appear likewife to have a Stronger affini- ty with this acid than the alkalis, according to Bergmann. Lime decompofes the neutral falts with bafe of. alkali, according to the experiments oS the Same chemift. ArSenick is uSed by the dyers j it is likewiSe ufed as a flux in glaSs-houSes, and in docimaftick works ; it alSo enters as a com- ponent part into Some glazes. Orpiment and realgar are very much uSed by painters v but arSenick is one of thofe produaions whofe advantages are not fufficient to compenfate for its bad effeas. This metal, which is very abundant, and very frequent- ly met with in mines, caufes the deftruaion of a number o£ workmen who explore them : being very volatile, it forms a dufl: which affeas and deftroys the lungs •, and the unhappy miners, aSter a languishing life of a few years, all periffi, Sooner or later. The property which itpoffeffes of being foluble in water,multiplies and facilitates its deftruaive power ; and It ought to be profcrib- ed in commerce, by the ftria law which prohibits the fale of poifon to unknown perfons. Arfenick is every day the inftru- ment by which victims are faerificed, either by the hand of wickednefs or imprudence. It is oSten miftaken Sor Sugar ; and theSe miftakes are attended with the moft dreadSul conSequences. Whenever there is the leaft reaSon to SuSpea its prefence, the doubt may be cleared up by throwing a Small quantity of the powder upon heated coals. The Smell oS garlick, and the white fumes, are indications oSthe preSenceoS arSenick. The Symp- toms which charaaerize this poiSon are, a great conftriaion of the throat, the teeth Set on edge, and the mouth ftrongly heated; an involuntary Spitting, with extreme pains in the Stomach ; vomiting of glairous and bloody matter, with cold Sweats and convulsions. Mucilaginous drinks have been long ago given to perSons poiSoned by arSenick. Milk, Sat oils, butter, &c. have been Suc- ceffively employed. Mr. Navier has propoSed a more direa counterpoiSon. He preScribes one dram (gros) of Sulphure of pot-afh, or liver oS Sulphur to be diffolved in a pint oS water which the patient is direaed to drink at Several draughts : the Sulphure-unites to the arSenick, and deftroys its caufticity and 288 CJi/Jif. effea. When theSe firft Symptoms are diffipated, he advifes the ufe of mineral fulphureous waters. He likewiSe approves of milk, but condemns the uSe of oils. Vinegar, which diffolves arfenick, has been likewiSe recommended by Mr. Sage. CHAPTER H. Concerning Cobalt. COBALT was employed by artifts to give a blue coi- our to glaSs, long before it was SuppoSed to contain a femi-metal. We are indebted to Brandt, a celebrated Swedifh mineralogist* for the knowledge of its properties, and metallick charaaer. The fpecifick gravity of fufed cobalt is 78119. See Briffon. Cobalt is combined in the bowels of the earth with Sulphur^ arfenick, and other metallick fubftances. 1. The arfenical cobalt ore is of a grey colour more or lefs deep, dull in its fraaure, and becoming black on expofure to the air, in confequence of an alteration in its arfenical part. This ore of cobalt cryftallizes in fmooth cubes, and affeas feveral varieties. 1 have a piece which has the form of tetrahe- dral pyramids, joined bafe to bafe. This fpecies of cobalt fome- times affeas a confufed cryftallization in dendrites, and is then called Knit-cobalt ore. Sometimes it is found in protuberances j ftalaaites, &c. 2. The fulphureous ore of cobalt reSembles the grey filver ore irt its texture : it contains iron and filver; and efRoreSces of a lilack colour, mixed with a yellowifh green.—Sage, Annal.- Chem. t. ii. Mr. De Lifle poffeffes Specimens of this kind, which came from the mine of Batftaes at Riddarhyttan. 3. Cobalt is mineralized by fulphur arid arfenick, in the mine of Tunaburg in Sundermania. The cryftallization of this fpecies is a cube Striated on its fix faces, and commonly truncated more or leSs deeply on its edges. This ore contains, according to Mr. Sage, fifty- five pounds of arSenick, eight oS Sulphur, two oS iron, and thirty-five oS cobalt. 4. The ores of cobalt are fometimes in effloreScence ; and the Sulphureous ore forms by its decompofition the Sulphate of cobalt. The Sulphure of cobalt, and the arfenical cobalt ore, pafs to the ftate of oxide in their decompofition ; and the furSace be- comes covered with a colour of peach flowers, more or lefs in- Affay of Cobalt Ores. Zaffer. asp tenSe. It is Sometimes coloured with an efflorefcence in the figure of ftars formed by radii applied to each other collaterally, and all tending to a common centre. This is an indiftina cryf- tallization, in which Mr. De Lifle thinks he obferved tetrahedral prifms terminated by dihedral Summits. The flowers of cobalt are frequently a mere powder, more or lefs coloured. Thofe ores which are in a State of complete decompofition are called Soft or Earthy cobalt ores. To affay an ore of cobalt, the firft proceSs is torrefaaion. Two hundred grains are afterwards ftifed with an ounce and an halS black flux. Mr. Sage is confident that more metal is ob- tained by mixing the oxide of cobalt with two parts of white glaSs, and a Small quantity of coal. When cobalt is mixed with biSmuth and iron, its oxide muft be diftilled with equal parts of the muriate of ammoniack, until the fait which Sublimes in the neck of the retort has acquired a green tinge. Mr. Sage, who gives us this procefs, obferves that feven or eight Sublimations are fometimes neceffary to de- prive the cobalt of all the iron andbifmuth which it contains. Cobalt is of a light grey Colour, compaa and brittle. It is not eafily fuSed, is not volatile, refills cupcllation, and refufes to amalgamate with mercury. The working of cobalt ores is very fimple. It confifts in roafting the ore in a reverberatory Surnace terminating in a long chimney, into which the vapours are received. Thefe vapours, or arSenical fumes, attach themSelves to the fides, and form a cruft,1 which is cleared off by criminals, who are condemned to this work for crimes that by the law deferve death. The cobalt ores of Saxony afford all the arfenick of commerce. When the oxide, of cobalt is cleared of arfenick, it is known by the name of Zaffer. The zaffer of commerce is mixed with three fourths of fand. This oxide, fufed with three parts of fand, and one of pot-aSh, forms a blue glafs, which, when pounded, CSted, and aSterwards ground in mills, included in large cafks, Sorms Smalt. In order to obtain the blue of various degrees of fineneSs, the fmalt is agitated in caflcs filled with water, and pierced with three openings at different heights. The water of the upper cock carries out the lighteft blue, which is called Azure of the Firft Fire : the heavier particles fall more Speedily ; and the azure brought out by the water of the three cocks, forms the different degrees oS finenefs, known under the names of Azure of the Firft, Second, and Third Fire. Bohemia and Saxony have hitherto poffeffed the exclufive power of fupplying us with theSe produas. A deScription of theSe capital works may be Seen in the mineralogical produaions 2...N 3p0 Habitudes of Cobalt with Acids. of Meffrs. Jars. The works of Saxony have been Supplied, for feveral years, by the cobalt ore difcovered in the Pyreneart Mountains, in the valley of Giften. But the Comte de Beuft has formed eftablifhments which fecure to us the benefit of this- commerce ; and he has even been fo fortunate as to find, near the village of Juget, a quartz Sufficiently charged with cobalt to admit of being fuSed without any addition of colouring matter. The eftablifhment of the Comte de Beuft is capable of manu- facturing fix thoufand quintals of azure, or enamel blue ; and is' able not only to fupply Our own wants, but to enter into compe- tition with the works oS Saxony for the Soreign trade.* He has likewiSe, in concert with the Baron Dietrich, diScov^ cred the proceSs of making powder blue , a Secret which was exclufively in the poffeflion of the Hollanders till the preSent time. Smalts are uSed in the preparation of cloths, laces, linens,. muffins, thread, &c. The azures are mixed with Starch, and form the blue fo well known and univerSally uSed by laundreffes. It is likewiSe employed in forming blue paintings on fayence, porcelain, and other potteries ; cryftals and glaffes are coloured blue by this Subftance; and it is alSo uSed in painting in frefco. The coarfeft blues are uSed by the confeaioners and others,- in the way of ornament; and in Germany they are ufed as Sand for writing-paper. The consumption of fmalt, azure, blue Sands, and zaffers, in the kingdom of France only, is eftimated at four thoufand quin- tals, which are fold from Seventy-two to fix hundred livres the quintal. Cobalt is foluble in the acids. One part of this metal, diftilled with four parts of fulphurick acid, affords the Sulphureous acid; and the refidue in the retort .is the Sulphate oS cobalt, Soluble in water, and capable of cryf- tallizing in tetrahedral rhomboidal cryftals, terminating in a dihedral Summit. Barytes, magnefia, lime, and alkalis decompoSe this fait, and precipitate the cobalt in the form oS oxide. One hundred grains of cobalt diffolved in the fulphurick acidr and precipitated by foda, afford one 1 rindred and forty grains of precipitate, and one hundred and Sixty when precipitated by chalk. * A deScription of the works of the Comte de Beuft may be feen it* the Defcription des Giles des Minerals, des Forges, et des Salens des Pr renees,par M. le Baron de Dietrich. Nickel. 2$ I The nitrick acid diffolves cobalt with effervefcence. The fo- lution affords cryftals in needles, which have not been ftriaiy examined. This Salt is deliqueScent, boils on the coals without detonating, and leaves a deep red calx. I have Seen this Salt in very ffiort beautiSul hexahedral pyramids. It decrepitates and fufes on charcoal. 4 * The muriatick acid does not diffolve cobalt in the cold, but by the affiftance of heat it diffolves a portion of it. This acid aas more effeaually upon the zaffer, and the folution is of a very fine green, and when diluted with water constitutes a very Sin- gular Sympathetick ink ; Sor it paffes Srom a lilack, or violet col- our, to purple, green, and black. The nitro-muriatick acid likewiSe diffolves cobalt, and Sorms the Sympathetick ink, which Hellot has called the Ink oSBiSmuth. Ammoniack likewiSe diffolves zaffer, and produces a liquor ©f a beautiSul red colour. CHAPTER III. Concerning Nickel. HYERNE appears to have been the firft who treated of nidc- d, under the name oS Kupfernickel, in 1794, in a work on minerals. Henckel confidered it as a fpecies of cobalt, or arfenick mixed with copper. Cramer has likewife placed it among the ores of copper ; and it was not until the year 1751, that Cronftedt obtained a new femi-metal from this pretended mixture. KupSernickel is Sound not only.in the German diftrias, but likewife in Dauphiny and in the Pyrenean Mountains. In dig- ging out a calcareous ftone for building, at Bareges, and oppo- se St. Sauveur, fmall veins and lumps of nickel were found in the calcareous fpar, fome parts of which were reduced to the ftate of green oxide. Mr. Sage, who analyfed that of Biber in Heffe, and that of Allemont, found it to contain gold. In order to obtain nickel from its ore, it muft firft be torrefied to difengage the arfenick ; and the oxide muft then be fufed with three parts of black flux, and a fmall quantity of coal. This metal is of a reddiffi grey colour. The Specifick gravity of fufed nickel is 7,8070. Briflbn. As it is very difficult to drive off all the arfenick by a previ- ous torrefaaion, the metal, when urged by a violent fire, ftill jfuffers arfenick to eScape. 29 z Properties of Nickel and Bifmuth. The methods pointed out by Bergmann and ArvidSon to pu- rify nickei,^onfiSt in repeated calcinations and reduaions ; but theSe operations Separate the arSenick only ; and Bergmann ad- mits that he did not Succeed in completely depriving it of its i- ron, though he treated it by every Suitable method. He Seems, difpofed to confider it as a modification of iron. The piffertation of Bergmann De Nicolo, Opufcula, t. ii. man be confulted on the nature of this metal; and alfo the A- nalyie Chimique of Mr. Sage? &c. The fulphurick acid diftilled upon nickel affords fulphureous acid, and leaves a greyiffi refidue, which, when diffolved in wai- ter, communicates to it a green colour. The Sulphate of nickel efflorefces in the air. fcfickel is attacked very ftrongly by the nitrick acid. The folution, when evaporated, affords cryftals of a beautiful green, in rhomboidal cubes. The nitrick acid likewiSe diffolves the oxide of nickel, and forms with it deliqueScent cryftals of a fine emerald green, and of a rhomboidal form, according to Bergmann. The muriatick acid diffolves nickel when heated. The Solu- tion produces cryftqls of the moft beautiSul emerald green, and of the figure oS long rhomboidal oaahedrons. Cronftedt has taught us that nickel combines with fulphur by fufion, and that the reSult is a hard yellow mineral, with, fmall brilliant facets. The fame chemift diffolved this laft met- al in the fulphure of pot-afh, and Sormed a compound reSem- bling the yellow copper ores. Nickel does not amalgamate with mercury. CHAPTER IV. Concerning Bifmuth. BISMUTH, or tin-glaSs, is a Semi-metal of a Shining yellow- ish white, difpoSed in plates and chatoyant. It has Some analo- gy with lead ; and, like that metal, it paffes off on the cupel, carrying thebafer metals along with it. The fpecifick gravity of SuSed biSmuth is 9,8227.—See Brif- fon. Bifmuth is the moft eafily fuSed of all the Semi-metals, aSter (in. It requires only the 200th degree of heat. It is found in various ftates in the bowels of the earth, either native, or combined with fulphur, arSenick, or oxigene. Ores of Bifmuth. 29$ I. Native bifmuth is fometimes cryftallized in cubes: Walle- rius and Cronftedt found it in this form in the mines of Schnee^ burg in Saxony. Thefe cryftals often re-unite in the form of dendrites, in the fpathofe or quartzofe gangues. Native bif- muth is Sound in maffes, covered with protuberances reSembling ftalaaites. Native biSmuth is, Srequently altered by a flight decomposi- tion oS its metalick SurSace. The native bifmuth of Saxony is Sometimes irifed, and mixed with arfenick : it has a reddifh jafper for its gangue. 2. ArSenical biSmuth is of a whitifh and brilliant grey colour. This ore is fometimes covered with ai> ochre of bifmuth, and often contains cobalt. I have feen pieces of arfenical bifmuth, from Schneeburg, in the form of dendrites on a gangue of jafper. 3. We are indebted to Mr. Cronftedt for the knowledge of a fulphureous ore oS biSmuth. That which he has defcribed is of a bluiffi brilliant grey colour. This Species frequently poffeffes the lamellated texture of the large plated galena, which has caufed Linnseus, Wallerius, and and others, to give it the name of Galena of Bifmuth. ft is found at Batpeas, at Riddarrhitan in Weftmanland. It decrep- itates on heated coals, and requires to be pulverized, in order to torrefy it without lofs. The galena of Bifmuth is fpmetimes ftriated. , The Sulphureous ore oS BiSmuth is Sometimes compaa, of an obScure colour, Sprinkled with Small brilliant points. That pS Schneeburg, in Saxony is oS this kind. Mr. De la PerouSe discovered, in 1773, on the mountains of "Melles in Ccnringes, in the quarter called Les Raitz, an ore of biSmuth, which reSembles this Small plated galena, and has no (External difference, excepting that it is leSs heavy. This ore is mineralized by Sulphur, in the proportion pf thirty-five livers per quintal. 4. Cronftedt, Linnseus, Juftj, and De Born, have fpoken of a biSmuth ore of a greeniffi yellow, Sound in Saxony, and in Swe- den. Mr. Sage communicated to the Academy, on the 17th of Auguft, 1780, the analyfis of an earthy folid, yellowifh green pre of bifmuth. He* obtained quartz in the proportion of one third, feme carbonick acid, thirty-fix pounds of bifmuth per quintal,and twenty-Sour grains oS filver: he Sound neither cop- per nor iron. Befides this green ore, he analyfed a yellow acid, flightly brilliant, and fometimes femi-tranlparent ore, which af- forded him nearly the Same reSults, but nine pounds more of biSmuth. $94 Habitudes and Magiflery of Bifmuth. This oxide muft be fufed in the blaft furnace. The fufibility of bifmuth renders the working of this ore ve- ry fimple, and the apparatus may be varied in feveral ways. Nothing more is neceffary than to throw the ore into the fire, and to make a, cavity underneath to receive the Semi-metal. BiSmuth, when heated to redneSs, burns with a blue flame, fcarcely perceptible. Its oxide riSes in the Sorm oS a yeilowifh fume, which, when condenSed, forms the flowers of bifmuth. ks weight is increafed, twelve per cent, in paffing to the ftate of oxide. Mr. Darcet has converted Bifmuth into a glafs of a dull vio- let colour. Bifmuth may be Substituted inftead of lead, in the procefs of cupellation. Its vitrification is even more fpeedy. The fulphurick acid, boiled on bifmuth, fuffers fulphureous acid to eScape, and partly diffolves the Semi-metal. The Sul- phate of biSmuth does not cryftallize, but is very deliqueScent. The nitrick acid attacks bifmuth, and is very Speedily decom- poSed. Nitrous gas is diSengaged, while the oxigene is fixed in combination with the metal. There is nevertheless a portion diffolved which is capable of forming a fait in rhomboidal, tetrar hedral prifms, terminating in a tetrahedral pyramid with unequal faces. This nitre detonates weakly with reddifh Scintillations ; and melts, Swells up, and leaves an oxide of a greeniffi yellow colour. This fait lofes its tranfparency in fhe air, at the fame time that its water of cryftallization flies off. The muriatick acid does not aa on bifmuth but in the courfe of a confiderable time ; and for this purpoSe it muft be highly concentrated. The muriate of bifmuth is of difficult cryftalliT zation, and ftrongly attraas the humidity of the air. Water precipitates this femi-metal Srom all its Solutions; and the precipitate, when well waffied, is known by the name of" Magiflery oS BiSmuth, or white paint Sor the complexion. This white is uSed as a pigment for the fkin ; but ftrong or Sulphu- reous vapours, and even the animal tranfpiration, convert it into metal, and alter its colours. The hair-dreffers, when they are defirous of converting hair to a black colour, Smear it with po- matum prepared with the magiflery of bifmuth. Bifmuth is ufed by the pewterers to give hardnefs to the me- tallick compofition of pewter. Mr. Pott has published a differtation, in which he affirms that phyficians have made uSe oS. Some preparations oS this Semi- metal : but it is proper that it Should be prohibited, becauSe it almoft always retains a portion of arSenick, and itSelf partakes of the noxious properties of lead. Alloys of Bifmuth. Antimony. *9S The white of bifmuth is very much ufed as a paint for the complexion. Its various folutions form fympathetick inks, which are more or leSs curious, on account of the Sacility with which this oxide is altered, and becomes black. Schluter, in his TreatiSe of the Fufion of Ores, pretends that it may be ufed in making the azure blue glafs. But it appears, from his own account, that he made ufe of a bifmuth ore very rich In cobalt. For he fays, that a moderate fire caufes this ore to fuffer its bifmuth to flow out, and that refidue is a grey and fixed earth, which may be employed to advantage in making the blue. This femi-metal unites with all the metals •, but very difficult- ly, in the way of fufion, with the other femi-metals, or the me- tallick oxides. Antimony, zinc, cobalt, and arfenick refufe this union. Bifmuth, fufed with gold, fenders it eager, and communi- cates to it its own colour. It does not render filver So brittle as gold : it diminiffies the red colour of copper, but is deprived of its own colour by uniting with lead ; the two metals in this cafe forming an alloy of a grey colour. When biSmuth is mixed in n Small proportion with tin, it gives it a greater degree of bril- liancy and hardnefs. It may be united with iron by a violent heat. BiSmuth amalgamates with mercury, and forms a fluid alloy ; a circumftance which has induced certain unprincipled drug- gifts to mix it with that metal. The Sraud may be known from the mercuTy being leSs fluid than before, and no other reft is neceffary than to diffolve the mixture in Spirit of nitre; for the biSmuth will be precipitated by the addition of water. This property, however, of amalgamating completely with mercury, may cauSe it to be applied with advantage in the Sil- vering oS glaffes, by an amalgam of tin, bifmuth, and mercury. This is, perhaps, the circumftance which has obtained it the name of tin-glafs. The fufible alloy of Mr. Darcet is a mixture of eight parts of bifmuth, five of lead, and three of tin. It melts in water at the feventy-third degree of Reaumur, and flows like mercury. CHAPTER V. Concerning Antimony. ANTIMONY is a femi-metal which has Singularly engaged the attention of alchemifts. They confidered it as the bafis of 20/6 .ar jejiuiu \Jrt of jx,.i,...i»..j, their great work ; and it is defcribed in their writings under the names of the# Radical Principle of Metals, Sacred Lead, &c. This femi-metal is famous for the difputes which were main- tained concerning it, at the beginning of the Sixteenth century. It was prohibited by a decree of parliament, at the Solicitation of the faculty of Paris. Poumief of Caen, a Skilful phyfician and chemift, was degraded by the Faculty of Medicine, for hav- ing employed it in 1609. This fame profcribed metal was re-eftablifhed in 1624; and at preSent affords the moft powerSul remedies poffeffed by the medical art. Bazilius Valentinus, a zealous partizan Of antimony, pleaded its cauSe with much warmth and enthufiaSm, in a work entitled Currus Triumphalis Antimonii : and Lemery has written a large volume to decry the preparations of this Semi-metal. As this Subftance afforded employment Sor a long, time to the alchemifts, its ftudy is rendered particularly difficult by the mul-i tiplicity of preparations, and the barbarous names which have been given to them, and to the variety of proceffes. But by con- founding preparations of the fame nature ; by bringing the anal-r agous products together, rejeaing at the fame time the numer- ous lift of barbarous names which have been beftowed on one and the fame thing ; and by reducing the proceffes to that Sim- plicity of which the well known preparations are SuSceptible ; we may Succeed in Sorming an accurate and preciSe idea of the hature and properties of this metal. Antimony is Sound in the bowels of the earth, in four differ- ent States. 1. In the metallick form. 2. Combined with arfenick. 3. Mineralized with fulphur. 4. In the ftate oS oxide. 1. Some authors pretend that antimony in the metallick ftate was difcovered in the year 1748, by Ant. Swab, in the mine of SahJburg, in Sweden. Swab affirms that it has the colour of filver, that its texture is formed oS large brilliant plates, and that it eafily amalgamates with mercury. Cronftedt, Wallerius, Linnseus, and Cartheufer, do not hefitate to admit oS native an- timony j but Lehman, Jufti, and Vogel deny its exiftence : and Mr. De Lifle thinks that this pretended regulus is nothing but the white arfenical ore of antimony. The abbe'SMongez affirms* that he has difcovered native antimony at Allemont in Dau- phiny. It is the fame ore which Mr. Sage has defcribed under the name of the Arfenical Ore of Antimony. Sulphureous Ore of Antimony. 7gj If this native Antimony really exifts, it is probably cryftalliz- ed like the metal itfelf, which is known to us, and whofe cryf- tals are either oaahedrons inSerted one in the other, or cube* placed one upon each other flantwiSe. 2. The arSenical ore oS antimony may be confidered as a true regulus by thoSe who, aSter Bergmann, do not admit of arSenick as a mineralizer: Sor the Pre is then confidered as an alloy of the two reguli. This ore is as white as filver, and exhibits large facets like an- timony. The Specimen was Sent Srom Allemont in Dauphiny, to Mr. Sage. Its gangue is quartz. Small faSces oS the grey and red ores of antimony ftriated-and radiated, and n:>t contain- ing arSenick, arc Sometimes Sound in the cavities oS this ftone. The antimony and the arSenick exift in the metallick Slate in this ore. The arSenick adheres So ftrongly to the antimony that it cannot be difengaged by torrefaaion. Mr. Sage combined the ore with fulphur, and obtained orpiment and realgar. This mineralogift has concluded, from his analyfes, that the arfenick exifted in the proportion of Sixteen pounds in the hundred. 3. Antimony is ufually mineralized by fulphur, in which Combination it exhibits three or four very diftina varieties. It is fometimes cryftallized oS a grey colour inclining to blue. The cryftals are very Srequently flender, oblong, hexahedral priSms, terminated by tetrahedral pyramids. The mines which are wrought in Auvergne afford us beautiSul prifms, of the fame geometrical Sorm, but thicker than thofe of the antimony Pf Hungary. Thefe laft cryftals foon become oS an irifed coh our; but thoSe oS the mines of Auvergne are not fo fpeedily Changed. I poffefs a large fpecimen of antimony from the neighbourhood of Alais, which is entirely covered with cryftals perfeaiy fimilar to thofe oS Hungary. It Srequently happens that theSe cryftals are conSuSed and indiftina, iri which caSe the Ore appears to be Sormed of very flender prifms applied fidewife to each other. That which is called plumofe antimony does hot differ Srom theSe varieties, excepting that its cryftals are very flender and detached. They are ufually of a blackifli grey. This variety has been arranged among the ores of filver, becaufe for the moft part it contains that metal. Ores of antimony have been found in feveral parts of France * but our province of Languedoc exhibits very curious fpeci- mens. We have them at Malbos in the county of Alais. This mineral has been wrought in the diocefe of TJzes; but the want of confumptlon has prevented the works from going on with/pint. Mr. De GenSanne lias obServed-in Vivarais a large fein oS ore oS antimony in a Stratum oS pit-coal. 2...0 298 Procefes, cfrV. with Antimony. The decompofition of the fulphureous ore of antimony pro- duces the red antimonial ore. The red ore more efpecially ac- companies the fpecular antimony of TuScany. Its Surfaces ap- pear to be corroded or rendered curious by decompofition; and when apiece is broken, it emits a powder which has the proper- ties of kermest. The decompofition of fulphureous antimony likewiSe produ- ces the Sulphate of antimony. Some varieties of theSe antimo- nial decompositions may likewife be feen in the Analyfe Chim- ique of Mr. Sage. Antimony is found in two Slates in the courfe of trade ; namely, in the form of crude antimony, and in the metallick form. Crude antimony is nothing elfe but the Sulphureous ore of an- timony cleared of its gangue. For this purpofe the ore is put into pots pierced at the bottom, and diSpoSed upon other pot* buried in the earth; The uppermoft pots which contain the min- eral are then heated'; the antimony becomes fufed, and flows, together with its fulphur, into the lower veffels, while the gan- gue remains in the upper pots. As the mixture of antimony and fulphur is very fufible, this procefs may be varied in a thoufand ways. I have myfelf wrought an antimonial- ore with the greateft economy, by fufing it in a furnace, over the arch of which I had difpofed the ore broken into pieces of five or fix pounds weight each. The heat was communicated to the whole mafs by five openings in the arch or roof; and the antimony, as it melted, ran down on the outfide of the furnace by means of channels cut in the convex part of the dome. This method afforded forty quintals of antimony in twenty-feven hours, by the confumption of between twenty and thirty quintals-of combuftible matter. We are acquainted with two methods of depriving crude an- timony of its fulphur. i. The flow and gradual calcination of the ore, which affords a grey oxide, and this urged by a violent heat is converted into a reddifh and partly tranfparent glafs of antimony. It does not affume this tranfparence unlefs it has been perfeaiy fufed. The glafs of antimony is a violent corro- five, but is capable of being correaed by mixing or kneading it with- yellow wax, and afterwards burning off the wax ; or other- wife by triturating it with- a volatile oil. This is the cerated* antimony of Pringle, fo much extolled in dyfenteries. 2. Or otherwife, the antimony may be deprived of its fulphur by pro- jeaing into an ignited crucible a mixture of eight parts of crude antimony, fix of tartar, and three of nitre. By keeping this; mixture for a certain time in fufion, the antimony is obtained' in the metallick ftate. Habitudes of Antimony. 299 In the large works antimony is torrefied in an oven refembling that of the bakers. Fifty pounds of dried wine lees or tartar are mixed with a hundred pounds of the oxide of antimony, and the mixture is then fufed in proper crucibles. The metallick button contains the form of the crucible ; and thefe loaves of antimony exhibit a ftar on their upper furface, which has been confidered as peculiarly charaaeriftick ; but is in Saa nothing more than a confufed cryftallization formed by oaahedrons in- serted one in the other. Copper, filver, and iron, when SuSed with the Sulphure of an- timony, feize its fulphur, and reduce it to the ftate of regulus. This has been diftinguiffied by the name of the metal employ- ed. Thus we hear of the regulus of Mars, of Venus, &c. Antimony is difficult of fufion; but when once melted it emits a white fume known by the name of Argentine Snow, or Flowers of antimony. Thefe fumes, when colfeaed, form very brilliant prifmatick tetrahedral cryftals: Mr. Pelletier has obtain- ed them in tranfparent oaahedrons. The argentine flowers of antimony are foluble in water, which they render emetick. The volatility and folubility of this fublimed oxide exhibit a refem- blance with the oxide of arfenick before treated of. We are in- debted to Rouelle for thefe obfervations on the properties of this antimonial oxide. Antimony is very flightly changed by expofure to air, in which it long preferves its brilliancy. The fpecifick gravity of fufed antimony is 6,7021.—^See Briffon. The fulphurick acid, by flow ebullition upon this metal, is partly decompofed. Sulphureous gas firft efcapes, and fulphur itfelf is fublimed towards the end. When four parts of the acid are ufed with one of the antimony, the refidue, after the aaion of the acid, confifts of the metallick oxide, with a fmall quantity of the fulphate of antimony, which may be feparated by means of diftilled water. This fulphate is very deliquefcent, and is eafily decompofed in the fire. The nitrick acid is decompofed upon this femi-metal with great facility. It oxides a confiderable part, and diffolves a por- tion, which may be fufpended in water, and forms a very deli- queScent fait, decompofable by heat. The* oxide prepared by this means is very white, and very difficult of reduaion. It is a true bezoar mineral. The muriatick acid aas upon antimony only by a long digef- tion. Mr. Fourcroy has obferved that this acid, long digefted upon the metal, diffolves it; and that the muriate of antimony obtained by a ftrong evaporation in the form of fmall needles, 3°° Antimonial Preparations. is very deliquefcent. It is fufible in the fire, and likewife vol- atile, Mr. Monnet has proved that twelve grains of the oxide of antimony are fufficient to faturate halS an ounce of the ordi- nary murjatick acid. Meffrs. Monnet and De Fourcroy have al- ways found that there is a portion oSthe muriate of antimony which is not volatilized by the fire : this depends upon its be- ^ng ftrongly oxided or calcined. If two parts of the corrofive muriate of mercury, and one of antimony, be diftilled together, a very flight degree of heat drives over a butyraceous matter, which is called butter of an- timony, or the fublimed muriate of antimony. It may be pre- fumed that the acid in this compofition is in the ftate of oxige- nated muriated acid, as it is in the corrofive fubfimate. The fublimed muriate of antimony becomes fluid by a very gentle heat ; and by virtue of this property it may conveniently be poured from one veffel to another : for nothing more is nec- effary than to plunge the bottle which contains it into hot wa- ter, and the muriate may then be poured out in its liquid State. I have feveral times obferved this muriate of antimony cryf- tallized in hexahedral prifms with dihedral fummits ; two fides of the prifm are inclined, and form that which the ancient chemifts diftinguifhed by the name of cryftals in the form of a tomb. This muriate is ufed as an efcharotick. When the fait is diluted with water, a white powder fails down, called pow- der of algaroth, or mercurius vitse. This powder does not contain an atom of the muriatick acid, and is tnerely an oxide of antimony produced by that acid. Simple water has feme aaion upon this femi-metal; for we find that it becomes purgative by remaining in contaa with it. Wine, and the acetous acid, completely diflblve it : but the e- metick wine is an uncertain remedy ; becaufe it is impoffible to determine with abfolute certainty the degree of its energy, which depends upon the very variable degree of acidity of the wine made ufe of. The emetick wine ought not therefore to be ufed but in external applications. The gaftrick fluids likewife diffolve this femi-metal, as is pro- ved by the famous perpetual pills. This purgative has been diftinguiffied by the name of Perpetual Pills; becaufe, being very little alterable, the pill may be tranfmitted from generation to generation. The acid of tartar forms a very well known fait with antimo-: ivy, which is much employed in medicine under the name of E- metick Tartar, Stibiated Tartar, or Simply Emetick. It is this,. fait which, in the New Nomenclature, is diftinguiffied by the. name of antimoniated Tartrite of Pot-affi. Antimonial Preparations. 3 OIL Jfn the examination oS the various authors who have treatd of the preparations oS this remedy, as well as by comparing the moft celebrated diSpenfiatories, we do not find two which pro- poSe an uniform proceSs which is conflant and invariable in its effeas. Some preScribe the crocus metallorum, or Semi-vitreous ox- ide of Sulphurated antimony ; others the glaSs oSantimonv; Others the liver of antimony, or fulphurated oxide of antimony: and others the fublimed oxide : fome combine feveral of thefe fubftances. But all in general adopt cream of tartar, or the acid- ulous tartrite of pot-afh, as a folvent. The proceffes vary not only in the choice oS the Subftances to be made uSe of, but even in the proportions in which they are to be employed. We likewife find varieties in the quantity of jvater ufed as a vehicle, which is not an indifferent circumftance; in the time prefcribed to digeft the fubftances together, a cir- cumftance of the greateft conlequence to be afcertained, becaufe the Saturation of tpe acid depends abfolutely and effentially upon jt. The choice of veffels muft likewife influence the effea of this remedy. Hoffmann has affirmed that the emetick loft its effea by a long ebullition ; and Mr. Baume has proved that iron precipitates the antimony after a time, and confequently that the iron veflels prefcribed in certain diipenSatories ought to be rejeaed. This variety in the propeffes muft neceffarily influence the re- fiilt; and we cannot be much Surprised that Geoflroy, who an- alySed Several antimoniated tartrites of pot-affi, Should have found from thirty grains to two gros and ten grains of metal in the ounce of this fait. Is it not therefore of great conSequence to prefcribe a uniSorm procefs, whoSe produa Should be invariable ? TheSe heroick remedies, which operate in Small dofes, ought to produce con- stant and invariably effeas through all Europe. It would be much more advantageous that Solemn proceedings Should be made Sor the preparations of thefe aaive remedies, than for the compofition of the theriaca, a true pharmaceutick monfter, the ciofe of which may with impunity he varied from a few grains up to three hundred. It follows, from the variety of the effeas of thefe Sovereign remedies, that confultations become almoft ineffeaual; becaufe the phyfician prefcribes according to the effeas of the remedies he is in the habit of ufing : and the art of medicine becomes no better than a difcouraging alternative of fuccefs and disappointment. At Montpellier, the emetick aas in a doSe of one or two grains; but in other places it does not operate in a lefs dpSc 3C2 Antimonial Preparations. than ten or twelve : and the ftibiated tartar fold by thofe whole- sale dealers in medicine, who Supply the country apothecaries, is ufually nothing but the fulphate of pot-afh, or vitriolated tar- tar moiftened with a folution of emetick. It is a thing greatly to be defired, that government, which does not apply its ltamp of approbation to objeas of luxury until they have paffed a rigid infpeaion, fhould prohibit traders from circulating with impu- nity, produas upon which the health of the citizen fo effential- Jy depends. TheSe are the Srauds and deceptions which have engaged me to form an establishment of chemical produas, in which intelligence and probity prefide over all its operations ; and I have Succeeded in my laboratories So far as to condua the proceffes with fufficient economy to afford produas faithfully made up, and invariable in their effeas, at the fame price as thoSe Sophifticated drugs with which the pubiick has hitherto heen poiSoned. The moft accurate procefs for maiking an excellent emetick confifts in taking very transparent glaSs of antimony, grinding it fine, and boiling it in water, with an equal weight of cream of tartar, nntil this Salt is Saturated. By filtration, and evapora- tion with a gentle heat, and fubSequent repoSe, cryftals of the antimoniated tartrite of pot-afh are obtained, whofe degree of emeticity appears to be Sufficiently conflant. The cryftals may be obtained in Several fucceffive produas by repeated evapora- tions. Macquer propofed the powder of algarorh, as more uniform in its power. Meffrs. De Laffone and Durande have adopted the opinion oS Macquer; and the celebrated Bergmann has fol- lowed the ideas of the French chemifts, with a few flight modir ficatioris. Take five ounces of cream of tartar Teduced into powder, and two ounces two gros oS the powder of algaroth precipitated by hot water, wafhed and dried. Add water to theSe, and boil them gently. By filtration and evaporation the cryftals of emetick tartar are obtained ; which may be given in the dofe of three grams, without fatiguing the Stomach or inteftines. The antimoniated tartrite of pot-afh cryftallizes in trihedral pyramids. It is very tranfparent, is decompoSed on the fire with crackling, and leaves a coaly refidue. Sixty parts oS water diffolve it. It effioreSces in the air, and becomes farinaceous. The folutions of this fait throw down a mucilage, which fixes, and forms a pellicle of confiderable thicknefs : it is the mucil- age of cream of tartar, which is infoluble in water, and partly foluble in alcohol. The fulphurick acid blackens it, but does not itfelf become coloared till after a long time. The nitrick Antimonial Preparations. 3°3 acid diffolves it partly ; and is itfelf decompofed, with the emif- fion of much nitrous gas. The alkalis and lime decompofe the antimoniated tartrite of pot-afh. Antimony, properly mixed with the nitrate,, decom- pofes that fait completely. Equal parts of the femi-metal and nitre being thrown into an ignited crucible, the fait detonates,, its acid is decompofed ; and at the end of the operation the cru- cible is found to contain the alkali which ferved as the bafe of the nitrate, and the antimony reduced to the ftate of white ox- ide : this is called Diaphoretick Antimony. The fame prepar- ation may be made by ufing the fulphure of antimony ; in which cafe three parts of the nitrate are ufed to one of the crude anti- mony. The refidue in the crucible, after the detonation, is compofed of the oxide of antimony, fixed alkali, a portion of the nitrate not decompofed, and a fmall quantity of fulphate of pot-afh. This compound is ftill known by the name of the Sol- vent of Rotrou. Water deprives it of all the falts it contains ; and leaves only the oxide of antimony, which is called Waffied Diaphoretick Antimony. If a fmall quantity of acid be pour- ed on the fluid which holds the falts in folution, a fmall portion of the oxide of antimony falls down, which was diffolved by the alkali of the nitre. The precipitate forms the ceruSe oS antimo- ny, or the pearly matter oS Kerkringius. Equal parts of the Sulphure of antimony and of nitrate, de-« tonated in an ignited crucible,, form the liver oS antimony or Sulphurated oxide oS antimony ; which, when pulverized and waffied, produces the Saffron oS metals, or crocus metallorum. The oxides of antimony have been confidered as very diffi- cult of reduaion ; and it was not without Surprize that I at firft obServed the Sacility with which they are all reducible by the black flux. This prejudice was eftablifhed and propagated Sor want of proper experiments. The alkalis do not fenfibly aa upon antimony: but the Sul- phures of alkali.diffolve it completely ; and it is upon this prin- ciple that an operation is Sounded by which we obtain a valuable remedy, known by the name of Kermes Mineral, to diftinguifh it from the vegetable kermes ufed in dying. The preparation is fimply a red Sulphurated oxide oS antimony. This remedy, firft pointed out by Glauber, who made it with antimony and the So- lution of nitre fixed by charcoal, is indebted for its celebrity to the wonderful cures it performed in the hands of Simon, a Chartreux friar ; whence it obtained the name of the Powder of the Chartreux. This religious man obtained the compofition from a furgeon named Laligerie, to whom it had been given by Mr. Chaftenay, lieutenant at Landau. Mr. Dodart, firft phyfi- 3°4 Antimonial Preparations. cian to the king, bought the fecret in the year 1720 \ and Mr. Laligerie rendered it poblick. According to his proceSs, the pounded Sulphure oS antimony is boiled Sor two hours, with one fourth oS its weight oS the Solution of fixed nitre or pot-afh, iri twice its weight oSvery pure water. ASter ebullition the fluid 19 filtered ; the kermes Sails down as it cools, and is afterwards dried. Laligerie direas that more of the Solution of fixed nitre be digefted on the metal, till it is Completely diffolved. L^'* gerie burned fpirit of wine or brandy upon it. The liquor which remains after the Kermes is fallen down, contains more kermes which may be difengaged b^ means of an acid. This kermes, which is paler than1 the former, is known by the name of Golden Sulphur of Antimony or the orange-coloured ful- phurated oxide of antimony. This procefi, is no longer uSed. That which Succeeded the beft with me, confifts in boiling tenor twelve pounds oS pure al- kaline Solution with two pounds of the falphure of antimony. The ebullition is continued for half an hour after which the flu- id is filtered ; and much kermes is obtained by mere cooling. I digeft new alkali on the antimony, until it is con famed. Tlfe kermes which I obtain by this means is of a beautiful tufted ap- pearance, Geoffroy, who analyfed the kermes in 1734 and 1735, found that one gros of kermes contained from Sixteen to feventeen grains of antimony, from thirteen to fourteen grains of alkali, and from forty to forty-one of fulphur. But Meffrs. Baume* Deyeux, de la Rochefoucauld, and De Fourcroy, are not con- vinced that the waffied kermes contains an atom of alkali which is not neceffary to its virtues. Kermes is likewife one of thofe remedies iri the preparation* of which the greateft care ought to be taken. It is neverthelefs s fubftance which all the apothecaries in the country buy at the fair of Beaucaire ; and the analyfis which I have feveral times made of this kermes, has convinced me that it very often is nothing clfe but pounded brick, mixed with vegetable kermes, and Sprinkled with a Strong folution of emetick tartar. I have found fome which was merely a mixture of the fine brown red^ and the calx of antimony. Lime and lime-water, digefted upon pulverized antimony, af- ford, even in the cold, at the end of a certain time a kind ofJ kermes, or golden fulphur, of a beautiful red colour. Antimony enters into the compofition of printers' types. It is likewife mixed with tin to increafe its hardnefs. It v/as for- merly ufed as a purgative : for this purpofe it was made into cups, in which water or wine was Suffered to ftand for a night mid taken by the patient the following- day. Char eelers and Ores of Zinc. 30^ V- The Sulphure of antimony is uSed as a fudorifick in Skin difor- eiprs. For this purpofe it is tied in a cloth, and digefted in the ptiSans appropriated to theSe diSorders. It is adminiftered in. pills for the fame purpofe. The Solvent of Rotrou has been much ufed to diffipate lym- phatick concretions, and pituitous Swellings. Waffied diaphoretick antimony is uSed in confiderable doSes to excite perSpiration. Some phyficians have confidered it as a medicine void oS effea ; and Boerhaave has maintained that its effea is not more confiderable than that of Lemnian earth. The kermes mineral is one of the moft valuable medicines that the healing art is acquainted with. It is incifive ; and may be . adminiftered in all pituitous cafes, when the ftomach fails, and and the lungs ate obftruaed. In a'more confiderable dofe it is fudorifick, and a ftill larger portion is emetick. It is employed in the dofe of from half a grain to three. The tartar emetick has received its name from its ufes. It is diffolved in water; and this Solution produces its effea. The liver of antimony, crude antimony, and the crocus rne- tallorum, are more efpecially ufed as purgatives in the veterina- rian praaice. They are given to horfes in the doSe of about an ounce. CHAPTER VI. Concerning Zins. ZINC is a metallick fubftance of a bluifh brilliant white col- our, very difficultly reducible into powder, but capable of being extended into very thin plates by the equal and gradual preffure of the flatting mill. From this laft property, which has been proved by Mr. Sage, we may confider zirtc as the intermediate fubftance between femi-metals and metals. Zinc is found naturally in various ftates. 1. Cronftedt affirms that he Saw a radiated cryftallization of a metallick appearance, which is found at Schneeburg, where it is called flowers of bifmuth, but which he found to be the regulus of zinc. This celebrated mineralogist does not venture to pro- nounce that it is native zinc. Mr. Bomare affirms that he found it in fmall pieces in the mines of lapis calaminaris in the duchy of Limbourg, and in the zinc mines of Goffer. This regulus may have arifen from the fcoriae of furnaces, or from the ancient works; fo that the exifbmce oS native zinc is Still confidered as very doubtful by :hefe mineralogifts. L'...P gotf Ajft+ of Blende. Ores of Zi"C 2. Zinc is ufually mineralized by fulphur, forming art ofC known by the name of Blende, which in German Signifies- tending or deceitful; a name which may have been given to it becaufe fuch diftricts as abound with this mineral are barren of other ores. The determinate crystallization1 of blende appears to be the aluminiform oaahedron, and fometimes the tetrahedron; but the modifications of thefe primitive forms are fo numerous, that the cryftals are found in an aftonifhing variety of figures. Moft commonly they are polyhedral cryftals of an indeterminate form, or fcarcely capable of being defcribed. Oh this circumftance depend the denominations of Blende with Large or Small Plates, Striated Blende, Compaa Blende, and other Species, which may be feen in the works of Meffrs. Sage, De Lifle, &c. The colour of thefe blendes is infinitely various} they are found yellow, red, black, femi-tranfparent, &c. All the blendes emit an hepatick fmell when' grated or tritu- rated. There is a kind of blende which exhibits a line of phofphorick flame when fcratched with a knife, or even with a tooth-pick. Mr. De Bournon found this yeilowifh, transparent, and phof- phorick blende, fimilar to that of Scharffenburg, at Maronne in- the mountains of Oifan, at the diftance of nine leagues from; Grenoble. The phofphorick blende contains fcarcely any iron. To make the affay of a blende, Mr. Monnet advifes folution of the ore in aqua fortis. The acid unites with the metal, and fep- arates the fulphur : after which the oxide of Zinc may be ob- tained by diftilling off the acid ; and this may be reduced. Bergmann obtains one part of the fulphur of thefe ores by dif- tillation. diffolves the refidue in acids, and precipitates the met- al Srom its Solutions. Mr. Sage diftils blende with three parts of fulphurick acid : the fulphur fublimes by this operation ; and the refidue in the retort is the fulphate of zinc, mixed with a fmall quantity of fulphate of iron, and other fubftances mixed with the zinc. I do not know any country where blende is wrought to obtain the zinc; but it is fometimes mixed with? lead; and in the working of this laft metal the former is occa- sionally obtained. Such is the ore worked at RammelSburg near Goflar in the lower Hartz. Great part oS the zinc is diffipated during the Sufion of the lead ore ; but a portion of this metal is obtained by a very ingenious procefs. Care is taken to keep the anteriour part of the furnace cool j againft which a ftone is plac- ed with a flight degree of inclination. The vapours of the zinc which are carried againft this ftone, are condenfed, and fall in drops into powder of charcoal j with which a ftone placed at - Analyfis of Calamine. 3*7 nihe bottom is covered. The femi-metal is defended from oxi- dation by means of the charcoal 5 and it is afterwards fufed and call into convenient forms. This zinc is always united with a fmall quantity of lead, and is lefs pure than that which pomes to us from India, under the name of Tutenag. I ftrongly calcined the blende of St. Sauveur, and mixed the powder with charcoal. I then put the whole into a retort whofe orifice was plunged beneath water; and by a violent heat, kept up for two hours, I obtained much zinc, which fell to the bot- tom of the water. 3. The decompofition of blende gives rife to the formation of the fulphate of zinc. The operation of nature is flow, but art has fupplied its defea. All the fulphate of zinc which is met with in commerce, is prepared at Rammelfburg. For this purpoSe aSter having roafted the galena mixed with the blende, it is thrown ignited into cifterns full of water, where it is leSt for twenty-four hours. The roafted mineral is three times extin- guished in the fame water ; aSter which the lixivium is evapo- rated, and put into coolers. At the end oS fifteen days the wa- ter is decanted, in order to feparate the cryftals of the fulphate of zinc. Thefe cryftals are afterwards fufed in iron veflels; and the liquor is poured into coolers, where it is Stirred till it congeals. We Shall examine the properties of this Salt in due courfe. 4. Zinc is likewife found in the ftate of oxide ; and it ap- pears to me that nature rriakes ufe of two means of converting the metal to this ftate. 1. The fulphur is Sometimes diffipated with* out the produaion of fulphate ; in which cafe it is replaced by the oxigenous gas, and the refult is that oxide of zinc which is known by the name of Lapis Calaminaris. I have found ftrata of lapis calaminaris at St. Sauveur, intermixed with layers of blende; and the tranfition of the blende to the ftate of lapis calaminaris may be followed in the moft interefting manner. 2. The ful- phate of zinc produced by the decompofition of blende in cer- tain circumftances, is itfelf decompofed by calcareous Stones, In the rich colfeaions oS Meffrs. Sage* De Lifle, &c. we See cryftals of calcareous Spar converted into calamine at one end, and calcareous at the other. Calamine cryftallizes in rhomboidal tetrahedral priSms, or in hexadral pyramids. It is Sometimes covered with protuberances ; often has the appearance of being worm-eaten ; and is, at other times, either fpongy or compaa. Its colour varies greatly. The county of Somerfet affords it of white, green, and other colours. 3oS Properties of Zinc. To make a good analyfis of calamine, Bergmann advifes So- lution in the fulphurick acid ; he obtains the fulphates of iron and of zinc. That of iron is decompofed by a known weight of zinc , and the metal is afterwards* precipitated by the carbo- nate of foda. He has afcertained that ninety-three grains of this precipitate are equivalent to one hundred grains oS zinc ; and from this weight he deduas that of the zinc made uSe of to precipitate the iron. Zinc may be obtained from calamine by diftillation. For this purpoSe I have uSed the Same proceSs as has already been mentioned in treating of blende. Zinc yields beneath the hammer, without extending itfelf. If it be caft into fmall plates, it may then be laminated, and re- duced into very thin and very flexible leaves. The fpecifick gravity of fufed zinc is 7,1908. See Briffon. Zinc, when heated, may be eafily pulverized. This opera- tion is very difficult without this precaution indicated by Mac- quer ; Sor it wears and choaks up files, and deftroys them in a ihort time : befides which, they have no confiderable aaion up- on it. It may likewiSe be SuSed and poured into water.—Thefe are the moft convenient means of pulverizing it. Zinc, treated in cloSe veffels, Sublimes without decompofition: but when it is calcined in the open air, it becomes covered with a grey powder, which is a true oxide ; and, if it be heated to rednels, it takes fire, emits a blue flame ; and white flocks iffue from it, which are called Philofophical Wool, Pompholix, or Nihil Album. This oxide may be 'SuSed into glaSs by an ex- ceedingly violent heat: the glaSs is of a beautiSul yellow colour. Zinc laminated into very thin leaves, takes fire by the flame of a taper, and burns with a blue colour mixed with green. Mr. De Laffone, who has written Several excellent Memoirs on zinc, confiders it as a kind of metallick phoSphorus. Water appears to have Some aaion upon zinc. When this femi-metal begins to be ignited, iS water be poured on it, the fluid is decompofed, and much hydrogenous gas is difengaged, Meffrs. Lavoifier and MeuiSner have afcertained this faa, in their fine experiments on the decompofition of water. Sulphurick acid diffolves it in the cold, and produces much hydrogenous gas. A Salt may be obtained by evaporation, in tetrahedral priSmatick cryftals, terminated by a four-Sided pyra-i mid. Mr. Bucquet has obferved that thefe prifms are rhomboi- dal. This fait is known by the name of Vitriol of Zinc, White Vitriol, Sulphate of Zmc : its tafte is considerably ftyptick. It is not much altered by expoSure to air when pure ; but Suffers its acid to eScape, at a degree of heat lefs than is required by the iulphate of iron. Habitudes of Zinc. 309 The nitrick acid attacks zinc with vehemence, even when di- luted with water. In this operation a great part of the acid is (decompofed ; but if the refidue be concentrated by flow evapo- ration, cryftals are obtained in compreffed and ftriated tetrahe- dral prifms, terminated by pyramids with four fides. Mr. De Fourcroy to whom we are indebted for this obfervation, adds, that the fait melts upon heated coals, and fpreads abroad with decrepitation, and a fmall reddiffi flame. If it be expofed to heat in a crucible, it emits red vapours, affumes the confiftence of a jelly, and preferves this foftnefs for a certain time. The ni- trate of zinc is very deliquefcent. The muriatick acid attacks zinc with effervefcence. Hydro- genous gas is produced, and black flocks are precipitated, which fome chemifts have taken for fulphur, others for iron, and which Mr. De Laffone confiders as an irreducible oxide of ?inc. This evaporated folution becomes thick, and refufes to cryftallize. It fuffers a very concentrated acid to efcape when heated, and the muriate itfelf fublimes by diftillation, The pure alkalis boiled on zinc obtain a yellow colour, and diffolve a part of the metal, as Mr. De Laffone has proved. Ammoniack digefted in the cold upon this femi-metal, difen- gages hydrogenous gas : this evidently ariSes Srom the decom- position oS the water, which alone, and without any mixture, is decomposed upon ignited zinc, as we have already obServed. Zinc mixed with the nitrate oS pot-aft), and thrown into an ignited crucible, cauSes this Salt to detonate ftrongly. Zinc decompoSes the muriate of ammoniack by fimple t: itur* ation, according to Mr. Monnet. Pott has obferved that a Solution of alum, boiled upon the filings of zinc, is decompofed, and affords the fulphate of zinc. Zinc fufed with antimony, forms a hard and brittle alloy. It unites with tin and copper, and forms bronze ; when com- bined with copper alone, it forms brafs. It is mixed with gunpowder, to produce the white and bril- liant ftars of artificial fire-works. It has been propofed to fubftitute this metal in the room of tin, for the internal lining of copper veffels ; and it is afcertain- ed from the labours of Mr. Malouin, that this covering would be more uniformly extended upon the copper, and would be harder than tin. It has been remarked that vegetable acids might diffolve it, and that thofe falts are dangerous ; but Mr. de la Planche has made all the experiments on this fubjea which fas extenfive knowledge, and zeal for the pubiick good could in- lpire ; and he is convinced that the falts of zinc, taken in a more confiderable dofe than the aliments prepared in veffels tin- ned with this femi-metal might contain, are not dangerous. 310 Manganefe. The fublimed oxide of zinc is much employed by the Ger- man phyficians, under the name of Flowers of Zinc. This remedy is given as an anrifpaSmodick. It may.be administered in pills, in the dofe of one grain. Tutty, or pompholix, is mix- ed with frefh butter, as an excellent remedy in diforders of the eyes. Mr. De Morveaux has fubftituted the precipitate of zinc to white lead, with the greateft advantage. It perfeaiy anfwers the intention of the artift, and is not attended wub. any dan? gerous conSequences in its ufe. CHAPTER VII. Concerning Manganefe, A MINERAL of a, grey or blackifh colour, foiling the fin* gers, and ufed in glafs-noufes under the name of Soap of the Glafs-makers, has been long known in commerce. Moft nau uralifts, fuch as Henckel, Cramer, Gellert, Cartheufejr, and Wab> lerius, have placed it among the iron ores. Pott, and Cronftedt did not confider it as a ferruginous fubftance. The latter found it to contain tin ; and Mr. Sage was long of opinion that it was an intimate alloy of zinc and cobalt. The celebrated Bergmann, in the year 1764, declared in print, that black manganefe ought to contain a peculiar metal; bufc he attempted in vain to extraa it. However, Mr. Gahn, a phy* fician at btockholm, fucceeded in obtaining a metal by the affift- ance of an exceedingly ftrong fire. We fhall explain his procefs after having fpoken of the different forms under which manga* nefe is found in the earth. Manganefe appears to be always found in the State of oxide ; but this oxide exhibits feveral varieties. 1. It is fometimes grey, brilliant, and cryftallized,-formed of very flender priSms confuSedly intertwined, and refembling the ore of antimony ; from which however it may be eafily diftin- guifhed by expofing it upon charcoal. For antimony fufes, and affords vapours ; but the manganefe remains unchanged. The cryftals of manganefe are ftriated, tetrahedral, rhomboi- dal prifms, terminating in four-fided pyramids. They fre- quently diverge from a centre. 2. Manganefe. is very often black and friable. This fpecies is found in the cavities of the brown haematites of the Pyrene* an Mountains. Ores of Manganefe. 311 I have difcovered an ore at St. Jean de Gardonenque, in the Gevennes. It is prodigioufly light, is found in ftrata, and in pieces which almoft always have the figure of an hexahedral prifm, eighteen lines in length, and thirteen or fourteen in thicknefs. This ore", upon which I have made experiments that I fhall prefcntly recite, is the pureft and fineft I am acquainted with. 3. Manganefe is fometimes of a reddiffi white colour, and eompoSed of groups of protuberances. Its fraaure is lamellated. That of Piedmont frequently has a grey reddiffi tinge, and ap- pears to be eompoSed of fmall plates. It gives fire with the fteel. The ManganeSe of Macon in Burgundy is of a deeper grey than that of Piedmont. That of Perigueux is intermixed with yellow martial ochre. It is found in feparate bodies, and not in veins like that of Pied- mont. 4. Moft of the white fpathofe iron ores contain manganeSc, and may be confidered as ores of this femi-metal. ^ Manganefe is likewife mixed with calcareous fpar, gypSum, jafper, haema- tites, &c. Mr. De la PerouSe has deScribed thirteen varieties of cryftallized manganefe found in the Pyrenean Mountains—See the Journal de Phyfique, Jan. r7"8*©» p. 67. 5. Scheele has proved that the afhes of vegetables contain manganeSe; and it Is to this mineral that the colour of>calcined pot-affi is owing. To extraa it, three parts of fixed alkali, one of Sifted afhes, and one eighth of nitrate, muft be fufed together. The fluid mixture muft then be poured into an iron mortar, where it congeals into a grcenifh mafs. This being pounded, and boiled m pure water, muft be filtrated, and Saturated with fulphurick acid. At the end of a certain time, a brown powder is depofited, which poffeffes the properties of manganefe. ^ To reduce manganefe to the metallick ftate, a crucible is lin- ed with charcoal; and into a hole made in this charcoal, a ball of manganefe, previoufly kneaded, with oil and gum ammoni- ack, is to be put; after' which the hole is to be covered with powder of charcoal. Another crucible muft then be fitted on, and the veffel expofed to a violent fire for an hour and a hal£ By following this procefs, I have feveral times obtained the metal from the oxide of manganefe of Cevennes. I have even fucceeded in reducing it, by fimply putting th3 powder of man- ganefe into a lined crucible. The button which is obtained almoft always has aSperities on its SurSace. Globules appear which fcarcely adhere to the maSs ; and theSe portions are uSually of a considerably deep green, while the internal part has a bluifh call. 313 Pure Air of Mangatlcfe This metal is more inSufible than iron. I have feveral time* obferved, when the fire has not been fufficiently Strong to fufe the manganeSe, that Several globules oS iron have appeared dif- perfed through the agglutinated oxide. Saline fluxes ought to be rejeaed, as infufficient for this re- duaiori. The great diSpofition which this femi-metal has to become vitrified, cauSes it to be diSperSed in the flux, where it remains SuSpended. I have feveral times by ufing the vitreous flux of Mr. De Morveau, obtained metallick grains forming a button, or elfe diSperSed in the flux ; which, when more narrow- ly examined, proved to be nothing but iron, cobalt or other met- als, according to the nature of the ore of manganefe. I have fometimes obtained even globules of lead ; becauSe the coarSeft glaSsin which the preSence of that metal is the leaft SuSpeaed* and which enters into the composition of the flux of Mr. De Morveau, contains it very often. The fpecifick gravity of manganefe has been eftimated by Bergmann, in proportion to that of water, nearly as 6850 to 1000. The oxide of manganefe, when ftrongly heated in clofe Veff- els, affords a prodigious quantity of oxigenous gas, and begins to afford it at a degree of heat lefs than is neceffary to difengage it from the oxides of mercury : a ftrong fire is required to diSen- gage the laft portions. Four ounces of the manganefe of Cev- ennes afforded me nine pints of oxigenous gas. The refidue in the retort was a grey oxide ; one part of which Was iricruft- cd in the fufed glafs, and had communicated to it a very rich vi- olet colour. The oxide of manganefe, diftilled with charcoal, affords the carbonick acid ; but, if it be calcined in an open veffel, it is re- duced into a grey powder, which lofes confiderable of its weight when the fire is very ftrong ; and at length agglutinates, and forms a green mafs. If it be mixed with charcoal, it does not fuffer any perceptible change in its colour. ManganeSe, expoSed to a very violent heat, vitrifies, and af- fords a glaSs of an obfcure yellow colour. The iron which i» mixed with it preferves its metallick form. Manganefe is eafily changed in the air, and is refolved into a brown powder of a greater weight than the femi-metal itfelf -t a certain proof of oxidation. Manganefe unites eafily by f\ifion with all the metals except pure mercury. Copper alloyed with a certain quantity of man- ganefe ib ftill very malleable. Eudiometer with Manganefe. 313 IS a mixture of the phofphate of urine with a fmall quantity of oxide of manganefe be placed upon charcoal, and be kept in fufion for a few inftants by means of the blue interiour flame of the blow-pipe, a tranfparent glafs will be produced, of a blue colour inclining to red ; which, when charged with a certain quantity of the fait, affumes the colour of a ruby. If it be kept in fufion for a'longer time, a flight effervefcence is perceived, and all the colour difappears. If the tranfparent globule be then Softened by the exteriour flame, the colour foon returns, and may be again effaced by keeping up the fufion for a time. The fmalleft portion of nitrate, added to the glafs, immediately re- Stores the red colour ; and, on the contrary, it is deftroyed by the addition of fulphurick falts. This globule of glafs, taken from the charcoal^ and fufed in the fpoon of perfea metal, be- comes red, and changes no more. Thefe experiments were made by the celebrated Bergmann. The fulphurick acid attacks manganefe, and produces hy- drogenous gas. This metal is diffolved more flowly than iron ; a fmell is difengaged fimilar to that which is afforded by the fo- lution of iron by the muriatick acid. The folution is as colour- lefs as water, and affords by evaporation tranfparent colourlefs cryftals in the form of parallelopipeds, and of a bitter tafte. Mr. Sage obtained them in tetrahedral prifms, terminated by four-Sided pyramids. This fait efflorefces in the air. If the fulphurick acid be poured on the oxide of manganeSe, and its aaion affifted by a gentle heat, an aftonifhing quantity of oxigenous gas is difengaged. The oxide of manganefe of Cevennes afforded me five pints and a half per ounce. When this oxide is deprived of its oxigene, the refidue Is a white pow- der, foluble in water, which by evaporation affords the fulphate of manganefe, already defcribed. The celebrated Bergmann has obferved that coaly matter, fuch as fugar, honey, and gum, affifted the aaion of the acid. This depends on the combination of the oxigene with thefe a- gents, to form the carbonick acid ; and the fulphurick acid aas more eafily upon the metal itfelf. Manganefe is precipitated from its Solutions by the alkalis, in the form of a whitifh gelatinous matter; but this precipitate foon lofes its colour, and becomes black by the contaa of the air. This phenomenon, which I have myfelf been witnefs to can be attributed, in my opinion, only to the abforption of ox- igenous gas : and I was convinced of this truth by agitating the precipitate in bottles filled with this gas ; for in this fituation the black colour is produced in one or two minutes, and a con- fiderable part of the gm is abforbed. I have conftruaed an eudw 314" Habitudes of Manganefe ometer as certain and as invariable as that which the liquid Sul- phure o/potafh, or folution of liver of fulphur, affords } but a large quantity of precipitate is required which muft be agitated againft the Sides of the veffels, in order that it may preSent a greater SurSace to the air, and that the abSorption may be more Speedy. I judge of the abSorption by caufing the veffel to com- municate, by a graduated tube, with Standing- water. The a& cenfion of this water in the tube is proportionate to the volume of oxigenous gas abforbed. The nitrick acid diflblves manganefe with efFervefeeuee* There always remains, a black. Spongy, and friable body, which exhibited to Bergmann all the characters of molybdfena. Other folvents prefented a fimilar refidue. The Solution of the nitrate of manganefe has frequently a dull colour, and affumes the red colour with difficulty. This folution does not afford folid eryf- tals, even by flow evaporation. The oxide of manganefe is foluble in the nitrick acicfc It is obfervable that this acid is not decompofed upon them, becaufe it finds the metal in the ftate of oxide- Carbonick acid is afford-' ed when coaly fubftances are added to affifl the Solution. When the nitrous or Surning nitrick acid is uSed, the Solution is made without the affiftance of theSe coaly Subftances, becaufe the ex- ceSs of nitrous gas Seizes the pxigene of the oxide. Thefe Solu- tions do not cryftallize. The muriatick acid diflblves manganeSe ; but when it' is di- gested upon the oxide it Seizes the oxigene, and paSfes in vapour through the water. This vapour is known by the name of Ox- igenated Muriatick Acid, whoSe properties we have already ex- plained. The refidue in the retort eorrfifts of a portion of acid combin. ed with the manganefe. This by evaporation affords a faline mafs, which attraas the humidity of the air. The fluorick acid with manganefe affords a fait of fparing fol- ubility, and this acid diffolves but little oS it : but by decompo- fing the fulphate, the nitrate, or the muriate of manganeSe by the fluate oS ammoniack, a fluate of manganeSe is precipitated. The Same phenomenon takes place with the phoSphoriek aeid. The acetous acid has but a weak aaion upon this fubftance. If it be digefted upon the oxide of manganefe, it acquires the prop- erty of diffolving copper, and forms tfhe beautiful acetate of cop- per, or cryftals of Venus v whereas the fame acid, digefted on copper, forms verdigris, or fimply corrodes it. This circum- ftance proves that the acetous acid becomes charged with oxy- genous gas, by the affiftance of which it diffolves the copper* luith various Bodies. 3*S The xwalick acid not only diffolves manganeSe, but like- wife the black oxide of manganefe. The Saturated Solution de- pofites a white powder, if there be not an exceSs of acid. This /fait is blackened by the fire, but eafily refumes the milky colour in the fame acid. The oxalick precipitates it in the form of fmall cryftallinc grains, when poured into Solutions made by the Sulphurick, nitrick, or muriatick acids. The acidulous tartrite oS pot-afh diffolves the black oxide, even in the.cold. The tartrite of pot-affi added to any folution whatever of manganefe, occafions a precipitate which is a true tartrite of manganefe. The carbonick acid attacks manganefe and the black oxide. The folution becomes covered in the open air with a pellicle, which confifts of manganefe that is feparated and oxided. It is white when it does not contain iron. If the muriate of ammoniack be diftilled with this oxide of manganefe, an elaftick fluid is difengaged, according to the ob- servation of Scheele, which he confiders as one of the princi- ples of ammoniack, without determining its nature. Mr. Ber- thollet has prpved that, when ammoniack is difengaged by a metallick oxide, there is a portion decompofed. The oxigene of the oxides unites to the hydrogenous gas of the alkali to forrn water, and the nitrogene gas efcapes. Eight parts of oxided manganefe take up by a gentle heat, in a glafs retort, three parts of fulphur; and .produce a mafs of a greeniffi yellow colour, which acids attack with an effervefcence and hepatick fmell. Manganefe itfelf does not appear to cOmbifie with fulphur. In order to feparate iron from manganefe, the alloy muft be diffolved in the nitrick acid, and evaporated to drynefs. The refidue muft be ftrongly calcined, and digefted with weak ni- trick acid, and a fmall quantity of Sugar, fhe acid takes up the manganeSe, which may be precipitated by the carbonate of pot-affi. The alloy may likewiSe be put into a Solution of the Sulphate oS iron. The acid abandons the iron to unite with the manga- neSe. The iron having leSs affinity with the acid than the manganeSe, may likewiSe be precipitated by a few drops of alkalki. The oxide of manganefe is chiefly ufed in glafs-houfes, to deprive glaSs of its green or yellow colour, which foda and Sand, when SuSed together, uSually affume. It has on this account been called the Soap of the Glafs-makers. It is alfo ufed to .colour glafs and porcelain of a violet colour. S1^ Char ablers of Lead. The confumption of this mineral is become more confiderable fince the diScovery of the oxigenated muriatick acid, which haq pointed out its ufes in bleaching of linen, cotton, &c. CHAPTER VIII. Concerning Lead. LEAD is the fofteft, the leaft tenacious, the leaft Sonorous^ the leaft elaftick, and one of the moft ponderous of metals. A cubick foot of lead weighs Seven hundred and ninety-four pounds, ten ounces, four gros, forty-four grains. Its fpecifick gravity is to that of water as 115523 to 10000, according to Brif- fon. Its fraaure is of a bluiffi white colour, darker than that of tin, and tarnifhing in the ah. It poffeffes a peculiar fmell, which is rendered perceptible by friction. A gentle heat is fufficient to fufe lead ; and the abbe Mongez obtained it in cryftals of the form of quadrangular pyramids, re- cumbent on one fide. Some authors affirm that lead is occa- sionally met with in the native ftate. Wallerius mentions three pieces of this kind. The German mineralogists likewife affirm that it has been found native in Villach in Carinthia. Mr. Genffane found in Vivarais, in four places, at Serremejanes, at Fayet near Argentiere, at St. Etienne de Boulogne, and near Villeneuve a\e Berg, « grains of native lead, from the Size of a " chefnut to an almoft imperceptible degree of fmallnefs ; they *• are all included in a very ponderous metallick earth, which is " precifely of the colour of the afhes of beech, or of litharge " reduced to an impalpable powder. This earth may be cut «< with a knife, but requires the hammer to break it." He found pieces which contained a fubftance fimilar to a litharge in their internal part. Linnaeus fpeaks likewife oS a native lead in cryftals.—Moft naturalifts agree to confider native lead as of a very problemat- ical exiftence. The various famples found in cabinets are prob- ably owing to ancient mine works. Time has changed their appearance, and incrufted them with various matters, which Seem to prove that they do not owe their formation to the ac- tion oS fire ; and this is the circumftance which may have im- poSed on certain naturalifts. 1. Lead is uSually mineralized by Sulphur; and this ore is known by the name oS Galena, It uSually cryftallizes in cubes, and in all the varieties of that figure. Various Ores of Lead. 3*7 Galena is diftinguiffied into feveral Species, i. Large diced galena. 2. Small diced galena. 3. Scaly or plated galena, 4. Compaa galena, in fmall brilliant grains reSembling fteel! It does not appear to be lamellated. TheSe diftinaions are more eSpecially neceffary to be attended to, becauSe the Species are very different in richnefs, and the al- loy oS filver, which is inseparable Srom galena. In general, the large diced galena is poor in filver, and is uSed to give a glaze to pottery, by the name oS AlquiSoux, or potters lead ore. That which is in Small grains is richer, and is wrought as a lead ore containing Silver. Galena is the only Species oS lead ore which is worked ; and we fliall relate all we have to Say concerning the working and affay of lead ores after having fpoken of the other ores. 2. Lead has been found mineralized by the fulphurick acid. Mr. Monnet has called this ore the pyritous lead ore. It is fri- able, dull, black, and almoft always cryftallized in very long needles, or in ftalaaites. It efflorefces in the air, and affords a true fulphate of lead. This appears to be of the nature of gal- ena : for as the fulphate is not developed but by the efflorefcence of the ore, it may be concluded that the fulphurick acid does not exift in the virgin ore itSelf. Lead mixed with iron is fometimes combined with the ful- phurick acid. A large quantity is found in the ifland of Angle- Sea. It cannot be reduced upon charcoal with the blow pipe, but it fufes into a black glafs.'—Dr. Withering has indicated this pre. 3. The carbonick acid very often mineralizes lead, and ex- hibits fome varieties which we fliall proceed to defcribe. A. The white lead ore.—This is almoft always found in the cavities of decompofed galena, or in the veins of powdery ftone containing galena. It is heavy, and frequently of a greafy col- our ; decrepitates in the fire ; and is eafily reduced by diftilla- tion, affording only water and the carbonick acid. Its form is almoft always cryflalline, but varies prodigioufly. The primi- tive form appears to be a dodecahedron, with ifofceles triangular planes. I have feen cryftals accurately of the form of an hexahedral prifm fometimes terminated by a fix-fided pyramid. The ores of St. Sauveur in the Cevennes have afforded us this variety ; Mr. Sage poffeffes white lead ore of Geroldicck cryftallized in cubes. White lead as tranfparent as flint gl.ifs has brct: found in V-wtand and in Siberia. 3i8 Varices Gres of Lead. The analyfis of the white lead of Siberia afforded Mr. Mac- quart, per quintal, fixty-feven parts lead, twenty-four carbonick acid, fix oxigene, and three water. B. Green lead ore.—This differs from the foregoing only in the modifications produced by the colouring principle, which is copper, according to Spielman ; and iron, according to the greateft number of chemifts. Its form is ufually that of a trun- cated hexahedron ; and this ore is not fo eafily reduced as the white ore. A , C. The black ore of lead.—Lead may return to the ftate ot galena by refuming the fulphur it had loft; and this "generation is not rare. It is enough that any hepatick vapour Should Strike the ore to effea t his conversion. The ores of Tfchopau in bax- ony, and thofe of tjuelgoet hi Lower Britany, exhibit hne in- ftances of this phenomenon. . The gradations,or intermediate fpecimens of thefe dirferent ores, eftablifh an infinite number oS Species, which the naturalift can never admit but as varieties. The tranfition of the white lead ore, to the black pre exhibits gradations of colour which it would be very fuperfluoas to defcribe. In the year 1766, Mr. lehmann defcribed a new fpecies of lead ore, called Red Lead. It was found in Siberia, m the en- virons of Catherineburg. Its cryftals are grouped) and adherent to quartz, to copper ores, or iron ; and fometimes to galena, with cryftals of white and green lead. It is frequently cryftal- lized in rhomboidal tetrahedral priSms, Short, and truncated ob- liquely. . Mr. Sage has confidered this lead ore as a variety of the pre- ceding Species, coloured by iron, of which Mr. Lehmann has proved the exiftence. The abbe Mongez thinks it is mineraliz- ed by the arfenical acid. Mr. Macquart has given us the moft valuable inSormation refpeaing the .red lead ore ; and has proved by an accurate analyfis that it contains, in the quintal, lead thirty-fix, oxigene thirty-Seven, iron twenty-five, and alumine two. " 4. The phofporick acid has like wife been found naturally combined with lead. This ore, discovered by Gahn, owes its <*reen colour to iron. It does not efferveSce with acids. In or- der to aflay it, it muft be diffolved in the nitrick acid by the af- fiftance oS heat, and the lead may then be precipitated by the fulphurick acid. The Supernatant liquor being decanted off, and evaporated to dryneSs, affords the phofphorick acid. This ore melts by the blow-pipe, and affords an opaque glob- ular mafs without reduaion. Its habitudes with fluxes re- ferable thofe of lead and its oxides. Affiiying of Lead. 3*2 Mr. De la Metherie has informed us that Mr. * * * an Eng- lish gentleman, by treating lead ores with the blow-pipe, had obferved that there was one whoSe globule cryftallized by cool- ing, aSter having been in perfea fufion ; and that thefe ores were not reducible by the blow-pipe. He fufpeaed they were mineralized by the phofphorick acid. Mr. De la Metherie and this gentleman took feven ounces of the green lead ore of Hoffs- gruard, near Fribourg in Brifgaw; which, when treated by the foregoing procefs, afforded them phofphorick acid. The phof- phorick acid' combined with minium afforded them a green Compound. The decompofition of the ores which we have defcribed fre-r quently affords the oxides of lead, or calciform ores. Thefe oxides at firft afford a powder which, being carried a- long by waters, often mixes with argillaeeous, calcareous, or quartzofe earths. TheSe oxides vary/more particularly in their colour, which affimilates them more or lefs perfeaiy to cerufe, mafficot, or minium. In order to make the affay of a'galena, it muft be pulveriz- ed and torrefied. The torrefied mineral, mixed with three parts of black flux, affords by fufion a metallick button, which indicates the proportions of the lead in the quintal of the ore. Bergmann propofes to make the affay of fulphureous lead ores by the nitrick acid, which diffolves the lead and not the Sulphur. The Solution is then to'be precipitated by the carbon- ate oS Soda; and one hundred and thirty-two grains of the precipitate are equivalent to one hundred of the metaL If the ore contains filver, ammoniack is to be digefted on the precipitate, from which it diflblves the oxide of filver. The various operations to which lead ore is fubjeaed to ob- tain the lead, are—i. It is Sorted, to Separate the rich or pure ©re from the pulverized matter, and the gangue which contains bo metal. 2. The ore is pulverized, and its gangue feparated by wafhing. 3. The ore is roafted in a reverberatory furnace, with occafional agitation, that it may prefent all its Surfaces to the air -y and when the external part begins to affume the form of a pafte, it is covered with charcoal, the mixture is Stirred, and the heat In- creafed. The lead then runs on all fides, and is colfeaed at the bottom of the furnace, which is pierced, and permits the metal to flow into a receptacle properly defended by a lining of charcoal. The Scoriae, which ftill retain much lead are fufed by a blaft furnace : the lead is call into pigs for file. To difengage the filver which the lead may contain, it is car- ried to the refining furnace; where, by the united energy of 3 2o Matuifallure of Red Lead. fire, and the wind of bellows direaed upon the melted lead, the metal is converted into a yellow fcaly oxide, called Litharge* This litharge is driven off in proportion as it forms; and the filver remains alone in the middle of the cupel. The colour caufes a dillinction of the litharge into litharge of gold, or litharge of filver. When the litharge is SuSed in contaa with charcoal, it reSumes its ftate of metal ; and the lead is fo much the better, in proportion as it has been deprived of the filver it contained. The fmalleft alloy of fine metal renders it brittle. Lead is fufible by a gentle heat. If it be kept for fome time in fufion, it becomes covered with a grey oxide ; which, when ex- pofed to a more violent heat capable of keeping it ignited, af- fumes a deep yellow colour, in which ftate it is called Mafficot. Mafficot may be converted into the red oxide, or minium, by the following proceSs. When the lead is converted into maffi- cot, it is thrown out and cooled by pouring water upon it; after which it is carried to the mill, and ground into very fine powder, which is wafhed in water. The particles of lead which could not be pulverized in the mill, remain in the veffel where the wafhing is performed. This oxide of lead is fpread out upon the hearth of the furnaca in which it is calcined. Lines are drawn on its furface ; and it is Stirred from time to time, that it may not clot together ; and the fire is kept up for forty-eight hours. When the minium is taken out of the furnace, it is put into large ffeves of Wood, and paffed through very fine net work, or cloth of iron Wire, placed over the cafks which receive the minium. We are indebted to Meffrs. Jars for this information, who have given very curious details refpecting the manufaaories of minium in the county of Derby. Mr. Geoffroy was of opinion, that, in order to form minium, no greater heat was required than one hundred and twenty de- grees of Reaumur's thermometer, but this heat is not adapted to works on a large feale ; for in thefe the roof of the furnace is kept at a red heat. The lead increafes in weight ten per cent by the calcination. All thefe oxides, urged by a ftronger heat, are converted into a yellow glafs, fo very fufible, that it penetrates and deftroys the belt crucibles. It is ufed in glafs-houfes, on account of its fufi- bility, not only to>ffiil the fufion, but likewife to render the glafs Softer, more ponderous, of a more unauous feel, and more fufceptible of bring cut and poiiffied. Thefe are the reafons for which it i? made a part of the compofition of flint glafs, t cryftal glafs. Habitudes of Lead. 3%\ The oxides of lead, diftilled without addition, afford oxige- nous gas by a violent heat.—Prieftly obtained it from minium, part of which was converted into globules of metal. When thefe oxides are fufed with coaly matter, the metal be- comes revived. The fulphurick acid boiled upon lead affords much fulphure- ous acid ; and an oxide is formed, which arifes from the com- bination of the oxigene of the acid with the lead. A portion o£ the lead is neverthelefs diffolved ; for if a fufficient quantity of water be poured on the refidue, a very cauftick fait is obtained by evaporation, in tetrahedral prifms, foluble in eighteen times their weight of water. This fulphate is decompofed by fire, lime, the alkalis, &c. Very hot fulphureous acid, poured into a leaden veffel, cor- rodes and deftioys it inftantly. The concentrated nitrick acid is readily decompofed upon lead, and converts it into a white oxide ; but when the acid is weak it diflblves the metal, and forms cryftals of an opaque white in the form of Segments of a three-fided prifm. I have fpeci- mens of the nitrate of lead in ray laboratory, which polfefs the form of truncated hexahedral prifms ; three of the fides being broader than the others, and exaaiy fimilar to thofe which Mr. De Fourcroy obtained by infenfible evaporation. This fait decrepitates in the fire, and is fufed with a yellow- ish flame upon ignited coals. The oxide of lead becomes yellow, and is reduced into globules.or metal. Sulphurick acid takes lead from the nitrick acid. The muriatick acid, affifted by heat, oxides lead, and diffolves a portion. This fait cryftallizes in ftriated hexahedral prifms. This muriate is flightly deliquefcent. Lime and alkalis de- compofe it. The fame acid poured on litharge decompofes it inftantly. Fifty or fixty degrees of heat are produced. The folution af- fords fine octahedral cryftals, of an opaque white colour, a ftyp- tick tafte, and oS very confiderable weight. This Salt decrepitates on the coals; and when the fire is in- creaSed, its water of cryftallization efcapes, and it becomes con- verted into a maSs of a beautiful yellow colour. Three parts of water, at fifteen degrees of temperature, dif- folve one part; and boiling water more than its weight. The pure alkalis precipitate it in the form of a magma, which occafions a kind oS miraculous mundi. The affinity of the muriatick acid with the oxide of lead is fo ftrong, that it is capable of decompofing all its combinations. Minium or litharge decompofes the muriate of ammoniack. 2...R * JM Hrsbfcu&s 4f Leaf. The fame OJridds^ triturated with marine fait, feparate the foda ;; arid it is upon thfeSe faas that Mr. Turner and . others have ef- tablifhed manufaaories for procuring foda by the decompofiiotir of marine fait.* The muriates of lead, calcined or fufed, afford a pigment of a beautiful yellow colour. The manufaaories of foda have af- forded a vePf confiderable quantity, which is Substituted inftead #f the fine Naples yellow. 4. The acetous acid corrodes lead ; and affords a white ox* He known by the name of white lead. To prepare this colour, the led is melted, and caft into plates- about hatf a line ki thicknefs, four or five inches wide, and two feet long. Thefe are rolled up in a Spiral form, in Such a man- ner that the revolutions remain at the diftance of half an inch from each other. They are then placed in pots, upon threVi poinis, which projea from the infide at about one third of the fceight. Malt vinegar is poured into thefe pots to the height ci£ the bottom of the lead, and they are buried in dutrg beneath ffceds. A great number of thefe are difpofed befide each other, and feveral- Strata are formed. Care is taken to cover each pot with a plate of lead and boards. At the expiration of a rriorffh* or fix weeks they are taken out, and the white lead is feparated. This white calx is then grdund in mills, and afterwards put in- to a vat, from which it is taken out to dry. The drying is per- formed in the Shade, becauSe the Sun impairs the colour. Fot this puifpoSe it is put into Small conical earthen pots ; arid When" fufficiently dry it is wrapped in paper, and diftributed for fade. Cerufe does not differ Srom White lead-, excepting that a more or leSs confiderable quantity of chalk is mixed with it. All the oxides of lead are foluble in vinegar. The folution of the acetate of lead, duly concentrated, cryftallizes m efBor* efcent tetrahedral prifms ; and forms the fait of Saturn, or ftrgar of lead. Cauftick alkalis diffolve the oxides of lead, and the metal may be precipitated by the addition of acids. When the arkalin* folution is concentrated, the lead re-appears nearly in the me- tallick form, and the alkali is found to have acquired a faint and very peculiar tafte. * I do not hear that foda has been Separated from common Salt By a method Sufficiently cheap for the purpofes of commerce. It is univer- fally underftood that Mr. Turner's profits arife from the Sale of the com- bination of muriatick acid with the lead, which forms the yellow pigment known in London by the name of Patent Yellow. It may be proauce«4 fimply by the fufion of litharge and common Salt; the allcaK being vo^- tUtaed, and driven off, if th: fire t» Sufficiently intenfe; T. Vfes ef L&fk "We, &>% TheuSea oS lead in the arts are muJriSari$us. It is ufed to ppflke water pipes, boilers, coverings Sor the ipofs oS buildings, itea-chofts and other articles of package. U is rendered prope.r for thefe uSea, either by laminating it, or by cabling it to flow out upon a bed oS Sand well rammed and levelled, or upon the •cfoth called ticking. It is likewiSe ufed toinake bullets ajjd&MaU&Qt. Thebui- Uts are call in moulds ; but the Small fhpt is made i# .the fol- lowing manner :—Lead is fiufed .with, a Small quaatity of arfen- ick, to render it more brittle; and when its temperature is .'fuch ^ as to admit of a card being plunged in it without burning, it is poured into a kind oS cullender, priced at the bottom with oaa- »y holest and containing lighted charcoal j t&ts cullender is held over watery aad the Ae*d affumes .a MkUfld form as It ■enters this liquid. Lead is ufed in the tinning of capper veffels. This is a per- nicious Sra<*d fupported by cjuflose, and'tolerated by the want of vigilance in the police. It is the more dangerous from the cir- cumftauce that fats, oils, and vieegar, ^owode ordifloive lead, which by that means becomes mixed with the aliments. Lead ore is likewiSe ufed 'to glaze pottery. For this purpofe jgalena is pulveriSed, and mixed with water. The vfiffel intend- ed to be glazed is dipped into tbi$fluid* after haying been ex- pofed to a firft baking. It accordingly becomes covered with ewter Spoons who uSually travel over the country, call the DroSs of Tin. They are very careSul to Sc.um the metal as often at poffible, to clear it of the drofs; and by this means they ayoid giving the peafant any more of bis old pewter than that which they cannot contrive to take away from him. They are very v.ell acquainted with the art of fufing this pretended drofs intp cood tin, by heating it in contaa with charcoal. The putty oS tin is ufed to polifh hard bodies: and to render glafs Opaque, which converts it into enamel. Tin takes fire by a violent heat, according to Geoffroy ; and a white oxide fub- limes, while part of the tin is converted into a glafe of a hyacin- thine colour. If tin be kept in fufion in a lined crucible, and the furface be covered with a quantity of charcoal to prevent its calcination, the metal becomes whiter, more Sonorous, and harder, provided the fire be kept up for eight or ten hours. Tin, and feveral other metals, may acquire a brilliancy they do not ufually poffefs, by pouring them out at the moment be- fore they would congeal in the crucible. This treatment Se- cures them Srom the oxidation they Suffer in cooling, when' they axe poured out too hot; and by this method, which is very fimple, I have procured to tin and lead a degree of brillian- cy which they would hardly be ihonght capable of exhibiting. Fuming Liquor of Libavius. 327 Tin, diftilfed in clofe veffels, affords a white fublimate in the iteck of the retort, which MaTgrafF took for arfenick j but Meffrs. Bayen and Chariard have proved that it was not that fab fiance. The aaion of acids upon tin varies according to the degree of purity of the metal. The fulphurick acid of commerce diffolves tin, by the affift- ance of heat; but part of the acid is decompofed, and flies ofF in the form of very penetrating Sulphureous acid. Water alone precipitates this oxided metal. Mr. Monnet has obtained cryf- tals by calcination, which reSemble fine needles, interlaced a- morrg each other. The fulphurick acid diffolves the oxide of tin much better. The nitrick acid devours tm. The decompofition of this foW vent is fo Speedy, that the metal is feen to be precipitated, al- moft inftantly, in a white oxide: IS this acid be loaded with all the tin it is capabfc of calcining, and the oxide be waffied with a confiderable quantity of diftilled water, a Salt may be obtained: by evaporation, which detonates alOfte in a crucible Well heated, and which burns with a white and thick flame, like that of a phofphorus. The nitrate of tin, diftilled in a retort, Swells up> boils, and filrs the receiver with a White and thick vapour, which has the Smell of nitrick acid. Mr. Baume even pretends that the nitrick acid does not dif- folve tin ; but Kunckel, and the famous Rouelle, have main- tained the contrary. Meffrs. f*ayen and Chariard diffolved five grains in two gros of pure nitrick acid, diluted with four gros of diflifled water. The muriatick acid diffolves tin, whether cold or heated. Daring the efferveScence, a very fetid gas is difengaged. The Solutioft is yeilowifh, and affords needle-formed cryftals by evaporation, which attraas the humidity of the air. Mr. Baume prepared this fait in a large Way for the callico printers. Out of twelve pounds of tin, diffolved in .forty-eight pounds off acid, he had a refidue of two ounces fix gros of a grey and folu- We powder, which Margraff had taken for arferrick. Mr. Ba'u- me has obferved that the cryftals of the muriate of tin differ ac- cording to the ftate of the acid.. He obtained cryftals fimilar to thofe of the fulphate of foda, in needles, or is fcales like thofe of the acid of borax. Mr. Moftnet afSferts that he obtained, by the diftillation of a muriate of tin, a fat matter, a true butter of tin, and a liquor refemblirig that of Libavius. The oxigenated muriatick acid diffolves tin fpeedily ^ and th« felt which it produces, poffeffes all the charaaers of the Ordina- ry muriate, according to Mr De Fourcroy. 32* Scarlet Compofition. That which is known by the name of the Fuming Liquor of Libavius, appears to me to be a muriate of tin, in which the acid is in the ftate of the oxigenated muriatick acid. To make this; preparation", tin is amalgamated with one fifth of mercury ; and this amalgam in powder is mixed with an equal weight of cor- rofive fublimate. The whole is then introduced into a retort,a receiver adapted, and diftillation proceeded upon by a gentle heat. An infipid liquor paffes over firft, which is followed by a Sudden eruption of white vapours, which condenfe into a tranfparent liquor, that emits a confiderable quantity of vapours, by mere expoSure to the air. The refidue in the retort, for an analyfis of which we are indebted to Mr Rouelle the younger, confifts of a flight lining in the neck of the retort, which contains a fmall quantity of the fuming liquor, fome muriate of tin, muri- ate of mercury, and running mercury. The bottom of the vef- fel contains an amalgam of tin and mercury ; above which lies a muriate of tin of a grey white, folid and compaa, and which maybe volatilized by a ftrong heat. The nitro-muriatick acid diffolves tin with vehemence : a vi- olent heat is excited ; and it frequently happens that a magma is obtained refembling pitch, which becomes harder in the pro- cefs of time. This happens when the very concentrated acid has diffolved too much of the metal ; and thefe inconveniences may be obviated by adding water in proportion as the Solution proceeds. The Solution of tin which constitutes the compofition for Scarlet, is mads with the common aqua-fortis, prepared with faltpetre of the firft boiling. This is a kind of nitro-muriatick acid, which unfortunately varies in its properties, according to the two variable proportions of muriate of foda and nitrate of pot-afh. For this reafon, the dyers are continually making complaints, either that the aqua-fortis precipitates, which hap- pens when it contains too fmall a quantity of muriatick acid; or that it affords an obfcure colour, which depends on an excefs of the fame acid. The firft inconvenience is remedied by diS- folving fea fait, or Sal ammoniack, in the aqua-fortis ; and the fecond by adding faltpetre. The moft accurate proportions to make a good folvent for tin, are, two parts of nitrick acid, and one of muriatick acid. Tin is likewiSe Soluble in the vegetable acids. Mr. Schultz, in his differtation De Morte in Olla, has demonftrated the Solu- bility oc this metal in acids. Vinegar corrodes it by a gentle heat, according to the experiments of Margraff. Moft of the tin in commerce is alloyed with various metals. That of England contains copper and arfenick artificially, ac« Alloys of Tin. 325) cording to Geoffrey; and naturally, according to the Baron Dietrich, Sage, &c. The tin of the plumbers or pewterers, called Pewter, contains feveral metals. The ordonnance in France permits them to add a fmall quantity of copper and Bif- muth. The firft metal renders it hard ; and the latter reftores the brightneSs which would elfe have been impaired by the cop- per, and renders it more Sonorous. The pewterers take upon themfelves to add antimony, zinc and lead ; the antimony har- dens it, the zinc renders it whiter, and the lead diminiffies its value. It is a defirable circumftance to poffefs the means of as- certaining the nature and proportions of thefe alloys. We are indebted for the following proceffes to Meffrs. Bayen and Char- lard. A. When tin contains arfenick, the folution in the muriatick acid exhibits a black powder, which confifts of arfenick feparated from the tin. This method is capable of rendering the two thoufand and forty-fecond part of alloy perceptible. B. If the tin contains copper, the muriatick acid, which at- tacks tin with facility, precipitates the copper in the form of a grey powder, provided there be no accefs of acid, and the fo- lution be made without heat. The copper is likewife precipi- tated by a plate of tin immerfed in the Solution. C. Bifmuth is Shewn by the fame procefs as the copper. D. To afcertain the mixture of lead, the nitrick acid muft be ufed, which corrodes the tin, and diffolves the lead. The pewterers have two methods of affaying this metal. 1. The affay of the ftone, which confifts in pouring it into a hemifpherical cavity made in a calcareous ftone, and terminating in a channel or groove. The workman attentively obferfes the phenomena of its cooling ; and from thefe circumftances, as well as from the crackling or noife which the tail of the affay affords when bended, he judges of the purity of the metal. 2. The affay by the ball confifts merely in a comparison of the weight of pure tin with that of adulterated or alloyed tin, poured into the Same mould. It cannot but be immediately perceived that theSe methods are very imperfea. The various metals which are prejudicial to health, are not added to the tin in a Sufficiently great proportion to produce any dangerous effeas. It Seems that Margraff was deceived by Some foreign circumftance, when he affirmed that the tin of Morlaix contains thirty-fix grains of arfenick in the half ounce ; for this quantity is more than fufficient to render the metal as brittle as zinc. Meffrs. Bayen and Charlard found no arfenick in the tin of B.mca and of Malacca. The tin of England never contains 2...S 33° Aurum Mufivum. more than three fourths of a grain of arSenick in the ounce of metal; and Suppofing this to be the maximum, the daily uSe of tin cannot be dangerous ; fince a plate in which arSenick exifted in this proportion, loft no more than three grains per month by eonftarit ufe, which amounts to the five thoufand Seven hundred and Sixtieth part of a grain of arfenick loft daily. The experi- ments Which theSe two Skilful chemifts have made upon animals, by mixing arfenick in larger proportions with tin, are Sufficient to remove every apprehenfion concerning the uSe of this metal. The lead alone may be produaive of dangerous confequences, becaufe the pewterers add it in a very confiderable proportion. The combination of tin with fulphur forms aurum mufivum,, or mofaick gold. The procefs for making it which has beft Suc- ceeded in my hands, is that deScribed by the Marquis de Bul- lion. It confifts in forming an amalgam of eight ounces of tin and eight ounces of mercury. For this purpofe, a copper mor- tar is heated, and mercury poured into it : and when it has ac- quired a certain degree of heat, the melted tin is poured in, and the mixture agitated and triturated till cold. Six ounces of ful-- phur, and four ounces of fal ammoniack, are then mixed ; and the whole put into a mattrafs, which is to be placed on a Sand- bath, and heated to Such a degree as to caufe a Saint ignition in the bottom of the mattrafs. The fire muft be kept up for three hours. The aurum mufivum thus obtained is ufually beauti- ful : but if, inftead of placing the mattrafs on the fand, it be immediately expoSed upon the coals, and ftrongly and Suddenly heated, the mixture will take fire, and a Sublimate will be form- ed in the neck oS the veffel, which confifts of the riioft beautiSul aurunflnufivum. I have obtained it by this procefs of a daz- zling colour in large hexagonal Scales. The mercury and the Sal ammoniack are not in ftrianefs necefSary to the produaion oS aurum mufivum. Eight ounces of tin diffolved in the muriatick acid, precipitated by the carbo- nate of Soda, and mixed with Sour ounces oS Sulphur, produced the Marquis oS Bullion a fine aurum mufivum : but this is not capable of increafing the effeas of the efearical machine, which proves that the compofition owes its virtue in that refpea to the mercury it contains in the proportion of fix to one, when prepared in the former procefs. This preparation is uSed to give a beautiful colour to bronze, and to increafe the effeas of the efearical machine by rubbing the cufhions. The Baron Kienmayerhas defcribed the following amalgam, eompoSed of two parts of mercury, one of zinc, and one of tin. —The zinq and the tin are to be fufed, and mixed together with the mercury ; and the mixture agitated in a wooden box, Silvering of Glaffes. Iron. 3 31 internally rubbed with chalk. The mafs is then to be reduced to a fine powder ; and employed in that ftate, or mixed with greafe. The effea of this amalgam is furprifing ; for by this means the power of efearical machines is inconceivably aug- mented. The amalgam of tin is capable of cryftallization. Mr. Sage's procefs confifts in pouring two ounces oS melted tin into a pound of mercury. After having introduced this mixture into a retort, he urged it by a violent fire for five hours on the fand bath. Np mercury was difengaged ; but the tin was found in a cryftallized ftate above the mercury which had not entered in- to combination. The lower part of this amalgam is compofed of grey brilliant cryftals in fquare plates,thin towards their edges, having polygonal cavities between each. Every ounce of tin retains in its cryftallization three ounces of mercury. The amalgam of .tin is ufed to filver looking-glaffes. For this purpoSe, a leaS of tin is Spread out upon a table oS the Size of the glaSs, mercury is poured upon it, and Spread about with a bruffi. This being done, a larger quantity of mercury is pour- ed upon the tin, fo as to form a covering of more than one line in thicknefs.' The glafs is Aided upon this covering, by prefent- ing one of its edges ; taking care at the fame time that its fur- face ffiall be beneath the level of the mercury, in order that the impurities which might hinder a perfea contaa may be driven before it. The plate of glafs is then loaded with weights equal- ly diftributed over its whole furface ; by which means all the exceSs of mercury is preffed out, and flows away through chan- nels made in the edges of the table. The air being driven out Srom between the amalgam of tin and the glafs by this ftrong compreffion, Serves greatly to render the amalgam adherent. Several days are required to elapSe before it be Sufficiently dry to admit oS removing theglaSs. Tin alloyed with copper Sorms bronze, or bell-metal. Seven parts oS biSmuth, five of lead, and three of tin, form an alloy which liquefies in boiling water. CHAPTER X. Concerning Iron. IRON is the moft generally diffuSed metal In nature. Al<- moft every mineral fubftance of this globe is coloured with it ; and its various alterations produce that truly aftonifhing variety of colours which are comprehended between the blue and the 33 2 Native Iron. deepefl red. This metal likewiSe exifts in the vegetable king* dom, where it constitutes an almoft inseparable principle. It even appears to be one of the produas of organization, or veg- etation ; for ic is found in vegetables which are fupported mere- ly by air or water. It is indeed contrary to found philofophy to SuppoSe that all the iron with which earths are impregnated, muft ariSe Srom the wearing of ploughshares : for, not to men- tion that the plough has not palled every where, we fee iron daily formed in vegetables. There is no reafon to fear that the. metal ffiould on this account become too abundant ; becauSe it is continually deftroyed by palling to the ftate oS oxide. If, on the other hand, we caft our attention towards the infi- nite number of ufes to which this metal is applied in Society, we fhall perceive that it is perhaps the moft effential to be known, becauSe it is the moft diffuSed, the moft uSeSul, and the moft employed. This metal is of a white livid colour, inclining to grey, obe-i dient to the magnet, and gives fire with quartz ; which laft cir- cumftance is attributed to the fufion and rapid combuftion of particles of the metal detached by the Stroke. It is the lightest of all metals except tin. One cubick foot of forged iron weighs five hundred and Sorty-five pounds. The Specifick grav- ity oS SuSed iron is 7.2070.—See Briffon. Iron is very hard, SuSceptible of a fine polifh, and very difficult of fufion. It may be drawn into very fine wire, of which the .firings of the harpficord are made. It becomes hard by ham- mering, without heat ; but when affifted by heat, it may be hammered into every imaginable form. Iron is univerfally difperfed ; but, by common confent, thofe places or matrices, in which the iron is fufficiently abundant to be wrought with profit, are called Iron Mines, or Ores. Iron is Sound native, without mixture, in Several places. We Shall not here mention thoSe ridiculous affertions, which have no other merit than that of having been authorized by the Suffrages of certain celebrated men.—" Ai.bertus Magnus de-; cidiffe caelum, imbre, maffam Serri centum Ijbrarum. Peterman- nus magna tempeftate, cum projeau multorum lapidum, ccelo molem Serri decidifie, quae in longitudine fexdecim, in latitudine quindecim in craffitie duos, pedes habuerit:" that is, of the weight of forty-eight thoufand pounds, and containing four hundred and eighty cubick feet.—Becher, Supplem. in PhyS. Subter. cap. iii. p. 599" We are indebted to Lehmann for a deScription of a piece of native iron poffeffed by Margraff, which came Srom Eibenftock in Saxony. The grain was distinguishable on both fides. Ores of Iron. 333 Henckel poffeffed a Small piece incrufted with a yellow earth; and the cabinet of the Royal School of mines poffeffes one which is covered with fpathoSe iron ore. Adanfon and Wallerius affirm that it is Sound in Senegal ; and Rouelle received a piece Srom thence which was very malleable. Simon Pallas Speaks o£ a maSs oS native iron Sound near the great river JeneSei in Sibe- ria. This iron is very Spongy, very pure, perfeaiy flexible, and proper to be Sormed into inftruments by a moderate fire. It is naturally incrufted with a kind of varniffi which preferves it Srom ruft. Mr Macquart doubts the legitimacy oS the native iron, de- Scribed by Pallas : he thinks that it may be confidered as fuSed iron. Mr. De Morveau does not believe in the exiftence of na- tive iron. Though Some doubts may be raiSed concerning the legitimacy of thefe pieces, and there may be reafons to confider Some of them as confequences of the aaion of fire, we cannot however refufe to admit of the exiftence of native iron, after the depofi- tions, faas, and atteftations which prefent themfelves on all fides in fupport of this truth. Iron, flowly cooled, cryftallizes in oaahedrons almoft always implanted one in the other. We are indebted to Mr. Grignon for this observation. I am in poffeffion of a piece of iron entire- ly covered with fmall tetrahedral flat, and truncated pyramids. Some of the pyramids have a b,ife of one line in breadth. It comes from the frontiers of the Comte de Foix. This iron is very feldom found unaltered by foreign admixtures ; but I think we may confider all the iron ores which are attracted by the magnet, as containing the native metal, difperfed in fome gangue: and we fhall attend to thefe fpecies before we treat of the oxides and martial falts, ARTICLE I. Concerning Iron Ores which are attracted by the Magnet. i. The oaahedral iron ore.—This ore has the form of oaa- hedrons, ifolated, and difperfed in a gangue of fchiftus, or cal- careous ftone. The cryftals are grey, very regular in their form and ftrongly bedded in the ftone. Their fize is from half a line to fix or Seven in diameter. Corfica and Sweden afford this kind. Mr. Sage obferves that oaahedral cryftals of iron are feme- times found in the finefl white marble of Carara. The black ferruginous fand which accompanies the hyacinths in the brook of Expailly, is an oaahedral iron ore, obedient to the magnet. 334 Iron Ores, The Magnet* 2. Iron ore in fmall plates or fcales.—The Small plates or feales which are attraaed by the magnet, and are found in moft rivers which contain gold, are an iron ore, nearly in the metal- lick State. This Sand forms the refidue which is left after the precious metal has been taken up by amalgamation. It is mix- ed with fragments of quartz, garnets, &c. I have found a large quantity in the fand of the river Ceze : it was alfo fent me from the neighbourhood of Nantz. I have received fome likewife from Spain ; and this fand has afforded me certain phenomena which appear to entitle it to a particular rank among the metals. Ajcids diflblve it by the affiftance of heat ; and always without effervefence, or the difengagement of gas. It communicates the fame colour to the nitro-muriatick acid as platina does. It is indecompofable by heat, either in the open fire, or in open veffels. I have endeavoured to reduce it by all the known flux- es, but in vain. It precipitates in the flux, mixes with it, and recovers its form and magnetick virtue by pulverizing the mafs. It poffeffes feveral characters of the fiderotetc, or phofphate of iron. 3. Iron diSperSed in flones renders them obedient to the mag- net. The ophites, the Serpentines, the micas, the pot-Stones, and Several marbles, are in this fituation. Iron diffeminated in a gangue oS quartz, or very hard jaSper, Sorms emery, which on account of its hardnefs is ufed to grind and polifh glafs. It comes to us from Jerfey and Guernfey, where it is plentifully found. The magnet itfelf is nothing elfe but the iron we fpeak of, modified in fuch a manner as to afford a paffage to the magnet- ick fluid, and to exhibit the known phenomena. The magnet is fometimes found in a regular form. Mr. Sage affirms that he poffeffes a fmall piece of magnet from St. Domingo, on which Oaahedrons are diftinguifhabfe. We likewife read, in the General Hiftory of Voyages, that at twenty leagues from Solikamfkai in Siberia, magnets are found of a cubical form and greeniffi eolour, of a lively brilliant appearance, which are reducible into glittering fcales by pulverizing. The magnet varies in its quantity of metal. Thofe of Swe- den and Siberia are very rich in iron ; but the magnetick force • is not in proportion to the iron they contain. There is reafon to think that the magnetick agent is a modifi- cation of the efearick power. 1. Iron which remains a long time in an elevated pofition becomes magnetick. 2- Inftru- ments of iron ftruck with lightning are ufually magnetized. 3. Two pieces of iron may be magnetized by rubbing them againft each other in the fame direction. 4. Black iron ores Decompofition of Pyrites. 335 are found in Sweden which are attraaed by the magnet, and whofe metallick particles are fometimes fo weakly conneaed to- gether that they are reducible into powder. We have feveral fpecies of thefe ores in Languedoc. This fpecies is in general very rich, and affords near eighty pounds of iron per quintal. 5. Iron appears to exift in the metallick ftate in fome other fpecies, fuch as the fpecular iron ore. But the metallick ftate is lefs evident and charaaeriftick, the metallick qualities being mOre changed ; and thefe ores are lefs attraaed by the'magnet. Thefe iron ores frequently exhibit metallick plates of a brill- iancy equal to that of fteel, and unalterable in the air. The ore of Mont d'Or, that of Eramont in the principality of Salm, and thofe of the mountains of Vofges, have afforded us very curious fpecimens. Thefe plates are fometimes hexagonal, formed by two hexahedral pyramids truncated near their bafe. The fpecular iron ore of Framont afforded Mr. Sage fifty- two pounds of iron in the quintal: the iron is very duaile, and acquires much fibre. The celebrated iron ore of the ifland of Elbe is of this kind, but it has not the plated form. Its cryftals are lenticular, with brilliant facets, which are dodecahedrons with triangular planes. Thefe beautiful groupes of cryftals are fometimes ffiaded with the moft lively colours. White clay, rock cryftal, cupreous- pyrites, &c. are found among them. The Lucquefe work this ore in the Catalan method, by Strat- ifying charcoal and the ore, one layer over the other. The fire is kept up by good bellows ; and when all the coal is confum- ed, the iron Is found colfeaed together in a mafs, which is car- ried to the hammer. The eifenman is a fealy fpecular ore. When it is rubbed, brilliant particles are detached from it ; which has caufed the miners of Dauphiny to give it the name of Luifard. The eifenram is an iron ore of a brilliant red colour, which contains plumbago and iron. ARTICLE II. Concerning Sulphureous Iron ores, or the Sulphurs of Iron. The union or combination of iron and fulphur forms the ful- phureous iron ore, martial pyrites, fulphure of iron &c. Thefe fulphures are very abundant, and are evidently formed by the decompofition of vegetables. I have feveral times found pieces of wood buried in the earth perfectly incrufted with pyrites. 33" Decompofition of Pyrites. The effea of Subterraneous fires is owing only to the mixture of theSe Sulphures with the remains of vegetables. Thofe Spe- cies of coal which efflorefce in the air, owe their ' decompofition only to the pyrites with which they are penetrated. It is like- wiSe to the decompofition of the pyrites that we muft refer the the heat of moft mineral waters. The fulphure of iron fome- times cryftallizes in cubes, and often in octahedrons. The un- ion of a number of oaahedral pyramids with their points to- wards a common centre, forms the globular pyrites. When the fulphur is diffipated, it fometimes happens that the pyrites lofes-neither its form nor its weight. It then becomes brown, is attraaed by the magnet, and is called the Brown or Hepatick Iron Ore.—See De Lifle. But the decompofition of pyrites moft commonly produces the fulphurick acid, which feizes the iron, diflblves it, and forms an efflorefcence on the furface. ' Advantage has even been taken of this property of the pyrites to eftablifh manufaaories of fulphate of iron, or copperas. The two valuable eftabliffiments which have been made of this kind, in the vicinity of Alais, work cer- tain ftrata of a hard ponderous pyrites. Thefe are formed into heaps upon areas, where the ground is flightly inclined. The efflorefcence is accelerated by watering the pyrites, grofsly bro- ken, with water. This fluid diffolves all the fait which is form- ed, and carries ii into refervoirs, where the folution fuffers all the foreign matters it may contain to fubfide. It is left at reft in thefe refervoirs, in which the fun produces a flight concen- tration of the fluid ; and the concluding evaporation is made in leaden cauldrons, with the addition of old iron, to faturate the acid with as much of that metal as poffible. The cryftalli- zation is performed in bafons, in which pieces of wood are dif- pofed toaffiit the formation oS cryftals. TheSe two manufaao- ries in Languedoc are capable, in their prefent ftate, of furnifh- upwards of forty thoufand quintals of copperas, if the demand required it. In order to facilitate the vitriolization, it is neceffary to give accefs to the air, becaufe the concurrence of this element is nec- effary to form the fulphurick acid. The fulphate of iron cryftallizes in rhomboids. It efflorefces in the air and gradually lofes its fine green col- our by the diffipatiori of its water of cryftallizaiion. If the fulph.it * of iron be expofed to heat, it liquefies, boils, becomes thick, and is reduced into powder. This powder, mixed with pulverized nut-galls, forms a dry ink, which Sever- al perSons Sell as a Secret, and which requires only the addition ef water to render it fit for ufe. Spathofe Iron Ores. 337 The Same powder urged by a Stronger heat, Suffers its acids to eScape ; after which there remains only a martial earth, or metallick oxide, known by the name of Colcothar. I attribute the formation of all the yellow or red earths, com- monly called ochres, to a fimilar decompofition of the pyrites. The heat produced by the decompofition of the pyrites has de- termined the refpeaive colours of thefe earths : and they may be caufed to pafs artificially through thefe various Shades, by treating them with various degrees of fire. I have difcovered in the diocefe of Uzes, banks of ochre of fuch uncommon fine- nefs, and fo very pure, that calcination converts it into a brown red, fuperiour to every thing before known in trade. The man- ufaaory which has been eftablifhed under my care, has acquir- ed all the celebrity which the fuperiority of its produas could not but neceffarily afford it. My experiments on thefe ochres, and the advantages which they may afford to the arts, may be feen in the work which I have published on this fubjea, print- ed for Didot the elder, at Paris. I likewife found at Mafs-Dieu, near Alais, a Stratum of red •chre of So beautiful a colour, that it could fcarcely be imitated. ARTICLE III. Concerning the Spathefe Iron Ores, or Carbonates of Iron. The carbonick acid is Sometimes combined with iron in ores ; and the reSemblance between this iron and Spar, has procured it the name oS the Spathofe Iron Ore. The formation of this ore appears to be owing to the mutu- al decompofition of the carbonates of lime, and the fulphates of iron. A folution of copperas, in which calcareous fpar was fuf- fered to remain, produced this ore, according to the experi- ments of Mr. Sage. Bergmann obtained from the ores of this kind, which he an- alyzed, thirty-eight ounces of the oxide of iron, twenty-four ounces of the oxide of manganefe, and fifty ounces of calcare- ous earth. It appears therefore that this ore contains two met- als united by a calcareous cement, which cryftallizes always in its own form, as we find in the lapis calaminaris, the calcareous grit, &c. The fpathofe iron ores are wrought at Cafeaftle, in the dio- cefe of Narbonne, at Bendorf on the banks of the Rhine, Eifen- artz in Styria, &c. 2...T 33* Bbg Ores of Iron, ARTICLE IV. Concerning the Bog Ores of Iron, or Argillaceous Iron Ores. Thefe ores confift merely of a martial oxide, in a ftate of greater or lefs purity, mixed with earthy fubftances of the nature of clays. They appear to have been depofited by water; and are ufually difpofed in ftrata, which are frequently marked out, and as it were feparated, into fmall prifms, whofe formation arifes fimply from the fhrinking of the clay. I. The eagle-ftone, or actites, ought to be ranked among the bog ores of iron. They are geodes of a round oval form, haing a hard external covering, while the cavity includes a de- tached nodule ; and the noife produced by Shaking one of thefe ftones, ariSes from the nodule being at liberty to move within the ftone. The name Qf eagle-Stone has arifen from a notion, formerly entertained, that eagles placed it in their nefts to facilitate the laying of their eggs ; and wonderful powers of rendering labours fafe and eafy, were attributed to it in the times of fuperftition. 2. We are acquainted with an iron ore in round pieces, re- fembling bullets, of feveral lines in diameter, which ought to be confidered as a variety of the preceding. Ah ore of this kind was begun to be wrought at Fontanez, near Sommieres; and we find a confiderable quantity of thefe metallick globules among our red earths in the neighbourhood of Montpellier. 3. The pureft oxide of iron, worn and carried along by waters* and afterwards, depofited, Sorms Strata of various appearances and colours. Thefe are called haematites. The colours ariSe Srom the various degrees of alteration in the oxide. They vary from yellow to the deepeft red. The red haematites is ufed in the arts to burnifh gold or filver. It is cue into long pieces, which when polished are known by the name of burniffiers. This blood-ftone is fometimes Soft enough to be uSed inftead of a crayon Sor drawing. Its figure is likewiSe Subjea to prodigious variation. It often appears as if compofed of fmall prifms applied one againft the ether, in which cafe it is called the fibrous haematites. In other fpecimens it is tuberculated. It is very frequently found in compaa irregular maffes, fuch as thofe of the ores of the county of Foix. This muft naturally exhibit the Same variety of Sorms as the calcareous ftalaaites, becaufe its mode of formation is pearly the fame. Plumbago, w Black Lead. 339 ARTICLE V. Concerning Native Pruffian Blue, or the Prufliate of Iron. Beccer fpeaks of a blue earth found at Turinge. Henckel informs us that a blue martial earth is Sound at Schneeburg and at Eibenftock. Cronftedt has deScribed a native Pruffian Blue 5 Mr. Sage found it in the turf of Picardy. It is likewife found in Scotland, in Siberia, &c. and I poffefs a fulphur of iron in a ftate of decompofition, which exhibits a true prufliate of iron upon one of its furfaces. ARTICLE VI. Concerning Plumbago, or the Carbure of Iron. The name of Plumbago is at prefent confined to that fhining fubftance of a blackiffi blue colour, which is uSed to make the pencils called black-lead pencils. It has a greaSy feel, exhibits a tuberculated fraaure, foils the hands, and leaves a black trace upon paper. Plumbago is found in many places ; that of commerce is brought to us from Germany. We receive it likewife from Spain, from America, and from England. It is alfo found in France. This mineral is almoft always difpoSed in Separate maffes in the bowels of the earth ; and it is probably on account of this form, that the ancients denoted it by the words Glebse Phambariae. The plumbago of England differs from the other fpecimens in its texture, which is much finer, and of a greater degree of brilliancy. The Engliffi do not take a larger quantity out of the mine than the market demands, in which they are careful to keep up the>price. The moft plentiful mine is in the county of Cumberland. The plumbago of Spain is always accompanied with pyrites, which efflorefce on the furface of the pieces; either in fmall cryftals, Similar to thofe of the fulphate oS iron ; or in a kind of Silky vegetation, analogous to that of plume alum. It is dug up in the neighbourhood of the town of Ronda, at the diftance of four leagues from the Mediterranean Sea. It is the worft kind which comes to market and is ufed only to give a Shining black colour to iron utenfils. 34# Plumbago, or Black Lead. The American plumbago, which Mr. Woulfe procured from Mr. Pelletier, breaks eafily, and exhibits fmall quartzofe grains in its internal part, as well as flight traces bf a whitifh clay. It is found in feparate maffes; and its texture appears to confift of the union of an infinity oS Small Scaly parts, which at firft fight might cauSe it to be taken Sor molybdena. France likewiSe poffeffes plumbago, and the chevalier Lama- non obServed it in Upper Provence, The mine is Situated near Col. de Bleoux. The black lead is found between two Strata of clay, not more than a few lines in thicknefs. It forms a Stratum of four inches thick ; or rather the Stratum confifts of Separate maffes, which are fometimes feveral feet in length. It is accompanied by a vein of pyrites. The inhabitants of Bleoux fell this produa at Marfeill es at about fifteen livres per quintal. Mr. de la Peyroufe found plumbago with tourmalines in the county of Foix, and Mr. Darcet brought it from the Py- renean Mountains. Plumbago is indeftruaible by heat without the prefence of air. Mr. Pelletier expofed it to diftillation, in the pneumato? chemical apparatus, by a violent fire during fix hours, without the plumbago having loft weight, or fuffered any other change. He expofed two hundred grains in a well-clofed porcelain cru- cible to the fire of the manufaaory at Seves, and it loft only ten grains. But when it is calcined with the concurrence of; air, it then burns, and leaves but a fmall quantity of refidue. Meffrs. Quift, Gahn, and Hielm obServed that one hundred grains, treated under a muffle in a Shallow veffel, left only ten grains of oxide of iron. Mr. Fabroni diffipated the whole of a portion of plumbago expofed under the muffle. This calcinar tion is a flow combuftion, which is facilitated by caufing the matter to prefent a large furface, and agitating it from time tQ time. If one part of plumbago, and two of very cauftick dry alkali, be heated in a retort with the pneumato-chemical apparatus, the alkali becomes effervefcent, hydrogenous gas is obtained, and the plumbago difappears. This beautiful experiment proves that the fmall quantity of water contained in the fait is decom- pofed ; and that its oxigene, by combining with the carbone of the plumbago, forms the carbonick acid. The experiment published by Scheele has been repeated and confirmed by Mr. Pelletier. The fulphurick acid does not aa upon plumbago, according to Scheele. Mr. Pelletier has obferved that one hundred grains of plumbago, and four ounces of the oil of vitriol, being digefted in the cold for feveral months, the acid acquired a green col-> Plumbago, or Black Lead. 341 •ur, and the property of congealing by a very flight degree of cold. The fulphurick acid diftilled from plumbago, paffes to the ftate of the fulphureous acid ; at the fame time that carbon- ick acid is obtained, and an oxide of iron is left in the retort. The nitrick acid has no aaion upon plumbago unlefs it be impure. Eight ounces of nitrick acid, diftilled from half a gros of purified plumbago, neither altered its Shining appearance, nor deprived it of its unauous feel. The muriatick acid diffolves" the iron and the clay which con- taminate native plumbago. Meffrs. Berthollet and Scheele a- vailed themfelves of this method to purify it. The liquor being decanted after digeftion.upon the plumbago, the refidue is then waffied, and fubmitted to diftillation to feparate the fulphur. The muriatick acid alone has no aaion upon plumbago, but the oxigenated muriatick acid diffolves it ; the refult being a true combuftion effeaed by the oxigene of the acid, and the carbone of the plumbago. If ten parts of the nitrate of pot-affi be fufed in a crucible, and one part of plumbago be thrown thereon by a little at a time the fait will deflagrate, and the plumbago will b'e deftroyed. The matter which remains in the crucible confifts of very effer- yefeent alkali, and a fmall portion of martial ochre. If plumbago be diftilled with muriate of ammoniack, the muriate fublimes, coloured by the iron. All thefe faas prove that plumbago is a peculiar combuftible fubftance, a true charcoal combined with a martial bafis. Plum- bago is more common than is imagined. The brilliant char- coal oS certain vegetable Subftances, more eSpecially when for- med by diftillation in cloSe veflels, poffeffes all the charaaers of plumbago. The charcoal oS animal Subftances poffeffes char- aaers ftill more peculiarly refembling it. Like it they are diffi- cult to incinerate, they leave the Same impreffion on the hands and upon paper ; they likewiSe contain iron, and become con- verted into carbonick acid by combuftion. When animal Sub- ftances are diftilled by a ftrong fire, a very fine powder Sublimes, which attaches itfelSto the inner part oSthe neck oS the retort. This Subftance may be made into excellent black-lead pencils, as I mySelS have proved. Carbone may be formed in the earth by the decomposition of wood together with pyrites ; but the origin of plumbago ap- pears to nit- to be principally owing to the ligneous, and truly indecompofable, part of the wood, which refills the deftruaive aaion of water, in its decompofition of vegetable fubftances. This ligneous fubftance difengaged from the other principles, muft form peculiar depofitions and ftrata ; and Mr. Fabroni has affured me that the formation of plumbago in water is a 34* Plumbago, or Black Lead. common phenomenon, of which he had feveral times been* witneSs. This chemift by his letter of the thirtieth of January, 1787, informs me that, in the dominions of the king of Naples, there are wells dug expreSsly Sor the purpoSe oS collecting an a- cidulous water, at the bottom of which wells a quantity of plum- bago is colfeaed every fix months. He SuppoSes that the black mud which is found beneath the pavements of Paris is plumbago formed in the humid way. There are likewife diftrias in Tufcany where plumbago is formed in the humid way. This fubftance is of confiderable uSe in the arts. It has been at all times applied to the purpoSe of making pencils, the moft efteemed of which are thofe which come from England. They are made at Kefwick in the county of Cumberland. The piece of plumbago is fawed into very thin plates. The edge of one of thefe plates is fitted into a groove Struck in a wooden cylind- er ; and the thin plate of plumbago is then cut off in fuch a manner that the cavity of the Small cylinder remains perfeaiy •• (filled. The duft Of plumbago is ufed to lubricate certain inftruments, and it is likewife made into pencils of an inferiour quality, by kneading it up with mucilage, or by fufing it with ,fulphur. The fraud may eafily be difcovered by the affiftance oS fire, which burns the fulphur ; or by means of water, which diffolves «the mucilage. Plumbago is likewife uSed to defend iron from ruft. The hearths, and plates oS chimneys, and other fimilar utenfils, which appear very bright owe their colour to plumbago. Horn berg lias communicated a procefs, in the year 1699, in which plum- bago is applied to this uSe. Eight pounds of hogs-lard are melt- ed with a fmall quantity of water, with the addition oS four ounc- es of camphor. When this laft is SuSed, the mixture is taken from the fire ; and while it is yet hot, a Small quantity of plum- bago is added, to give it a leaden colour. When this is to b« applied, the utenfils muft be heated to Such a degree, that the hand can Scarcely be applied to them. In this ftate the compo- fition muft be rubbed on them, and afterwards wiped when the piece is dry. Thofe who prepare fmall Shot, make ufe of black lead to pol« ifh and glaze it; the Shot is rolled or agitated together with a quantity of plumbago. Plumbago is likewife uSed to make ra- zor ftrops. When kneaded up with clay, it forms excellent crucibles, which we receive from Paffaw in Saxony. One part of plumbago, three of argillaceous earth, and a fmall. quantity of cow's dung very finely chopped, form an excellent lute iot Affay of Iron Ores, 34} retorts. Mr. Pelletier has ufed it with great advantage. This kite is exceedingly refraaory ; and the glafs will melt without the covering changing its Sorm. To make the affay of an iron ore, I find the following flux very advantageous :—I mix four hundred grains of calcined borax, forty grains of flacked lime, two hundred grains of ni- trate, and two hundred of the ore to be allayed. I pulverize this mixture and place it in a lined crucible, which I cover. The heat of a forge furnace is fufficient to effea the reduaion. In the fpace of half an hour, the button of metal is found depofited at the bottom of the vitrified flux. The procefs for working iron mines varies according to the nature of the ore. The metal is fometimes So little altered, and fo abundant, that nothing more is neceffary than to mix it with the coal, and SuSe it. This fimple and economical proceSs Sorm* the bafis of the Catalan method, which may be employed ia. treating the SpathoSe iron ores, thoSe of Elbe, the haematites, and other rich and pure ores. But it cannot be applied to fuch as contain much foreign matter capable of becoming converted into flag. For this reafon, the experiments made in the county of Foix on the ores of various countries, and various qualities, have not Succeeded. On this head, the work of Mr. De la Pey- roufe, and the Memoirs of the Baron de Dietrich, may be con- fulted. The furnaces in which iron is fufed, are from twelve to eigh- teen feet in height. Their internal cavity has the form of two four-Sided pyramids joined baSe to baSe. The only flux added to the ore is the calcareous ftone, named (by the French) cafliney if the ore be argillaceous; but, if the gangue be calcareous, the the workmen employ argillaceous earth, which is named herbue. The furnace is charged at the upper part ; and the fire is ex- cited by bellows, or hydraulick machines. The ore melts as ir paffes through the coal and is colfeaed at the bottom, where it is maintained in a liquid ftate. At the end of every eight hours it is fuffered to flow out into the mould, or hollow channel made in the fand. Crude iron, caft in Suitable moulds, Sorms chimney-backs, pots, cauldrons, pipes, and an infinity of utenfils or vafes, which could not be obtained without difficulty by forging the iron. The works which are eftablifhed at Creufotin Burgundy furpafs every thing which can be defired in this fpecies of induftry. This firft produa is called Caft or Crude Iron. It is brittle j but may be rendered duaile by heating it again, and hammer- ing it. For this purpofe the pig iron is fufed again, and ftirred lphile in the ftate o£ fufion : alter which it is carried to the forge 344 Crude or Cafl Iron. hammer. By this treatment the iron becomes duaile, aSTumei a fibrous texture, and is formed into fquare or flat bars for the purpofes of trade. Iron is likewife capable of a degree of fuperiority, which is given to it by placing it in contaa with coaly fubftances, and Softening it to fuch a degree that thefe may penetrate into its texture. It is then known by the name of Steel. We are in- debted to Mr. Jars for very interefting accounts of the fteel manufaaories in England. The manufaaory eftabliffied at Amboife is not inferiour to thofe of England, as was afcertained by comparative experiments made upon the produas of the fev- eral manufaaories, at Luxemburg, on Friday the 7th of Septem- ber, 1786. We may therefore divide the different ftates of iron into caft or crude iron, iron properly fo called, and fteel. It is clear that thefe three ftates are nothing more than modifications of each other ; but the circumftances on which they depend, and the principle which eftablifhes their difference, were till lately un- known. The celebrated Bergmann has given an analyfis of the vari- ous ftates of iron, and has drawn up the following table : Caft Iron. Steel. Iron. Inflammable Air I 40 48 5° Plumbago 2 20 0 50 0 12 Manganefe l5 25 15 25 15 25 Siliceous Earth 2 25 j 0 60 0 175 Iron 80 30 j 83 65 84 45 This celebrated chemift has confirmed by his refults the con- clufion of Reaumur, who always confidered fteel as an interme- diate ftate between crude and malleable iron. We are indebted to three French chemifts, Meffrs. Monge, Vandermonde, and Berthollet, for a quantity of much more accurate information refpeaing all thefe ftates. We may confider iron ores as natural mixtures of iron, oxn gene, and various foreign fubftances. When an ore is wrought the objea of the operator is to clear the iron of all thefe mat- ters. To effea this feparation, the ore is thrown into the fmelr- ing furnaces, with different proportions of charcoal. Thefe mat- ters are heated together until they arrive at the hotteft part, where the mixture falls ; and, after fuffering the ftrong action of the fire, is precipitated in fufion, and forms a fluid mafs at the bo: torn of the furnace. The earths and ftones, nearly in a vitrified ftate, float above the Huid ; and the oxigene, being Various States of Iron. y^c partly driven out, remains likewife in greiter or lefs quantity in the crude iron. The crude iron is either white, or grey, or black. In our enquiries concerning the caufe of thefe three kinds of i- ron, and their qualities, we can refer them only to the propor- tions of fofeign principles contained in the crude iron. Thefe principles are carborte and oxigene. I. Crude iron contains carbone. The ladles which are ufed to agitate, take up, and pour out this melted metal, become cov- ered with a coating Of plumbago, which contains nine tenths of carbone : and caft-iron, ftrongly heated in contaa with the coal, Suffers a part to efcape or exude Srom its Surface when it is flowly cooled. Crude iron emits Sparks when it is heated : the acids which diffolve it always leave a refidue which is pure- ly carbonaceous. The hydrogenous gas, which is obtained by treating theSe irons with acids, always affords the carbonick acid by combuftion. 2. Crude iron contains oxigene. Several mineralogifts at- tribute the fragility and brilliancy of crude iron to its ftill con- taining iron in the ftate of oxide. This opinion, which is gen- erally adopted, Suppofes the exiftence oS oxigene. Crude iron urged by a violent heat in cloSe veffels, affords the carbonick acid and paffes to the ftate of Soft iron ; becauSe its oxigene then u- nites to the carbonaceous principle, and constitutes the carbori- ick acid, which exhales, and clears the crude iron Srom the two ■ptihciples which altered its quality. Oxigene and carbone exift therefore in crude iron, but they Stray exift in three different ftates—i. A large quantity of car- bone, and a fmall quantity of oxigene. 2- An exaa propor- tion between thefe two principles. 3. Much oxigene and a Small quantity of carbone.—Now we find thefe three ftates in the three kinds of crude iron which we have diftinguiffied, as is proved by analyfis ; and, as we may judge by the fecondary proceffes, to correa thefe imperfea ions, or to convert crude iron into the malleable ftate. 1. In the firft cafe, that iron which contains an excefs of car- bone is agitated or ftirred as it flows out. It is kept a long time expofetl to the aaion of the bellows, and the fmalleft Doffi- ble quantity of charcoal is made ufe of. We fee that in this procefs the propereft methods are uSed to Sacilitate the combuf- tion oS this exceSs of the carbonaceous principle. 2. In the Second cafe, that kind of iron in which the princi- ples exift in accurate proportions, requires only* the aaion of neat to unite and volatilize the two foreign principles. The crude iron is put into a flare of ebullition by the difengagement of the acid-nhich is formed, «nd exhale;. 2...U 34$ Various States of Iron. 3- In the third kind, or that which contains oxigene in cx- cefs, the bellows are urged lefs violently; and the metal is pen- etrated with coal in order to combine with the oxigene. Here therefore we fee theory and praaice go together. The former explains the ufual manipulations, and affords us principles in cafes wherein experiment too Srequently fails. Steel is a kind of iron which contains carbone only ; and its exiftence may be proved by all the experiments which have been mentioned as demonstrations that crude iron contains it. Carbone may be given to iron—1. In the fufion of the ore. 2. Or, afterwards, by the cementation of iron with coaly fub- ftances. 1. In fome parts of Hungary, and in the county of Foix, iron ores are wrought which contain the m-tal nearly in the difen- gaged State ; and the caft iron, when duly hammered, affords Iron and fteel in a greater or lefs quantity, according to the management of the fire, the quantity of air, afforded by the tuyere, the quantity of coal made ufe of, and the nature of the ore. In this operation, the iron being fcarcely at all calcined in the ore, becomes charged with coaly matter only, and the re- fult is fteel. 2. If the coaly principle be combined with iron in a duaile State,, and deprived oS all foreign matter, the combination being effeaed by a cementation or otherwise, the iron will pafs to the Slate of fteel ; and the qualities of this fteel will vary according to the proportions oS carbone. The purity of the iron, and the care which is taken to avoid the oxidation of the metal, eftablifh the various kinds of fteel which are met with in commerce. The nature and the principles of fteel being once admitted and eftablifhed, the following faas will explain themfelves. 1. Since fteel contains no foreign principle but carbone, it is not furprifing that it remains unchanged by a violent heat in clofe veffels. 2. Steel, repeatedly heated, and expofed while hot to a cur- rent of air, lofes its properties, and paffes again to the ftate of foft iron. 3. Steel kept plunged for a time in crude iron in which oxi- gene predominates, becomes itfelf converted into foft iron. 4. Soft iron kept for a time plunged in crude iron, wherein carbone predominates, becomes converted into fteel. 5. Iron, by paffing to the flate of fteel, increafes in weight one hundred and Seventieth part. Duaile iron would be a very foft metal, if it were cleared of all foreign fubftances. Various States cf Iron. 347 From all thefe faas we may conclude—i. That crude iron is a mixture of iron, carbone, and oxigene. 2. That the produas of crude iron are white, grey, or black, according to the propor- tions of oxigene and carbone which it contains. 3. That the fteel of cementation is merely a mixture of iron and carbone. 4. That fteel which is over cemented, is an iron containing too large a quantity of carbone. 5. That iron would be a very foft metal, if it were not mixed with a greater or lefs quantity of oxigene and carbone. Forged iron is diftinguiffied into foft iron, and eager or brit- tle iron, by us (the French) called Rouvvain. This laft has a coarfer grain than the other : it is divided into red ihort iron, and cold Short iron. The caufe oS this phenomenon is known ; it ariSes Srom a phoSphate oS iron, which was difcovered by Bergmann. This celebrated chemift conftantly obferved a precipitate to be formed in the Solutions oS cold Short iron in the Sulphufick acid. It was a white powder, which he called Si- derite, and at firft SuppoSed to be a peculiar metal ; but Mr. Meyer of Stetiu has proved that it is a true phofphate of iron. Soft iron does not afford it. All the irons of Champagne afford about a dram, or gros, in the pound of iron. In order to obtain fiderite, it is neceffary that the folution Should be Saturated by a gentle heat on the Sand bath. If the folution be made too quickly, the fiderite is then mixed with ochre, which alters its purity and whitenefs. A precipitate is formed, which take6 place fo much the more Speedily, as the folution is more diluted with water each time after filtration. The precipitate is formed in the firft three or four days ; a fecond is obtained towards the fixth day ; and that which afterwards falls down is mixed with ochre. Siderite may likewife be obtained by diffolving iron in the nitrick acid, and evaporation to drynefs. The iron is oxided by this firft op- eration. More nitrick acid being poured on this refidue, dif- folves only the fiderite, without touching the oxide of iron. A fecond evaporation muft then be made ; and the refidue muft be diluted with water, to evaporate the laft portions of nitrick acid : and that which remains is fiderite. It is foluble in the fulphurick, nitrick, and muriatick acids, from which ic may be precipitated by pouring into the folution as much alkali as is ne- ceffary to faturate the acid Solvent. If the alkali be added in ex- cefs, ochre is then precipitated ; and the refult is a phofphate, and a fait arifing from the union of the acid made ufe of and the alkali which has ferved for the precipitation. The fixed and volatile alkalis, and lime water, decompofe fiderite. It is likewife deepmpofed by projeaing it upon fufed sitre. 34* Habifwhs of Iron. When it has been precipitated by ammoniack, cryftals may be obtained by evaporation, which when treated with powder of charcoal affords phofphorus. The ochreous precipitate affords iron by reduaion ; it is therefore a combination of the phof- phorick acid and iron. Every Solution oS iron is precipitated in the Sorm oS fiderite by the phofphorick acid. The effea of the tempering of iron likewife deferves the at- tention of the chemift. 1 am of opinion that the hardnefs and brilliancy which iron acquires by this operation j arifes from its. integrant parts, which are feparated by the heat, being kept an4 left at a certain diftance from each other by the fudden cold, which drives out the heat, without bringing the conftituent prin- ciples of the mafs together. The iron is then more brittle, be- caufe the affinity of aggregation is lefs. Iron is eafily oxided. A bar of iron which is heated a long time in the forge furnace, becomes oxided at its furface ; and the coatings of metal which pafs to the ftate of oxide, are fepa- rated from the mafs in the form of fcales. The moft degraded and the moft altered metal, in the ftate when it is no longer at^ traaed by the magnet, forms an oxide of a reddiffi brown col- our, known by the name of Aftringent Saffron of Mars, or the Brown Oxide of Iron. The colour of this oxide varies according; to its degree of ox- idation. It is yellow, poppy-colour, or red ; and is eafily re- duced into a black powder, when heated with coaly matters. The combined aaion of air and water conftitutes a martial oxide, known by the name of Aperitive Saffron of Mars. This compofition is produced by the combination of oxigenous gas and carbonick gas with the iron. The exposition oS the iron to a humid atmofphere rufts it Speedily, and cauSes it to pafs to the ftate of aperitive Saffron oS Mars. This preparation is a true carbonate of iron. Water likewife r.as upon iron. If iron filings be put into this liquid, and be agitated from time to time, the iron becomes divided, and blackens ; and by decanting the turbid water, a black powder is depofited, which is called the Martial .ZEthiops of Lemery or the Black Oxide of Iron. It is a commencement of calcination effeaed by the air contained in the water ; but more efpecially by the decompofition of the water itfelf. The fixed and volatile alkalis, in the fluid ftate, being digelled upon iron, oxide a flight portion, which falls down in the form of aethiops. All acids aa more or lefs upon iron. 1. The concentrated fulphurick acid is decompofed by boil- ing upon this metal. If the mixture be difliikd to drynefs, the Habitudes of Iron. 349 »etort is found to contain fublimed fulphur, and a white mafs, partly Soluble in water, but incapable oS cryftallization. But if the diluted Sulphurick acid be pcured upon iron, a con- siderable- effervefcence ariSes in confluence oS the disengage- ment of hydrogenous gas. In thL operation, the water is de- compofed, its oxigene is employed to calcine the metal, while the hydrogene is difengaged ; and the acid aas upon and dif- folves the metal without being decompofed. This folution, when concentrated by evaporation, affords the fulphate of iron, which we have already treated of. 2. The nitrick acid is decompofed rapidly upon iron. The folution is of a red brown colour, and fuffers the oxide of iron to fall down at the expiration of a certain time. If new iron be plunged in this folution, the acid diflblves it, and lets fall the oxide which it held in folution. * If the Solutions be concentrated, martial ochre of a red brown colour falls down. If the concentration be carried ftill further, a reddiffi jelly is formed, which is partially foluble in water. Iron precipitated from its folution by the carbonate of pot- afh, is eafily diffolved by the Superabundant alkali, and Sorms the martial alkaline tincture oS Stahl. Mr. Maret has propofed to precipitate the iron by the cauf- tick alkali, to make the aethiops immediately. Mr. Darcet, in rendering an account oS the proceSs pS Mr. Maret to the Royal Society of medicine, has propoSed that oS Mr. Crohare, which confifts in boiliug upon the iron water acidulated with the mu- riatick acid. Mr. De Fourcroy made a courSe oS experiments upon the martial precipitates, which throws much light upon the caufes oS the aftonifhing varieties obServed in them. He has proved that the whole depends either on the nature oS the acid, or the manner oS operating at the time of making thefe precipitates, or the quality of the precipitant. 3. The diluted' muriatick acid attacks iron with vehemence. Hydrogenous gas is difengaged, which arifes from the decompo- sition oSthe water. If the Solution be concentrated, and leSt to cool when it is oS the thickneSs of fyrup, a magma is formed ; thin, flattened cryftals are perceived, which are very deliqueScent. The muriate of iron, diftilled in a retort by the Duke D'Ayen, exhibited very Singular phenomena. The firft produa was an acid phlegm. At a ftronger heat, a non-deliquefcent muriate of iron fublimed, at the fame time that very tranfparent crvltals rofe to the roof of the retort, in the form of the blades of razor*, which decompofed the light in the fame manner as the beft prifms. At the bottom of the retort there remained a ftyptick 35a Formation of Ink. defiquefeent fait, of a brilliant colour, and a foliated appearance, which exaaiy refembled the large plated talc, improperly called Mufcovy GlaSs. This laft Salt expoSed to a violent heat, afford- ed a Sublimate more aftoniihing than the former produas. It was an opaque Subftance, truly metallick, which exhibited Sec- tions oS hexahedral prifms, polifhed like fteel. It was iron re- duced, and fublimed. 4. It was long fince known that iron is precipitated from its Solutions by vegetable aftringent fubftances ; and the black dyes, and the Sabrication of ink, are founded on this known faa. But it was not till lately that an acid has been proved to exift in thefe Subftances, which comhined with the iron, and which may be obtained from all thefe aftringent vegetables, either by fimpfe, diftillation, or by mere digeftion in cold water. The moft fim- ple procefs is the following : Infufe one pound of powder of nut-galls in 2} pints of pure water. Leave the mixture together for four days, frequently Shaking the infufion. Then filter, and leave the fluid in a veflel fimply covered with blotting paper. The liquid becomes cover- ed with a thick pellicle of mouldineSs, and a precipitate falls down in proportion as the infufion evaporates. Thefe precipi- tates collected, and diffolved in boiling water, form a liquor of a blown yellow colour, which, evaporated by a gentle heat, de- pofites— 1. A precipitate which refembles fine fand. 2. Cryftals difpofed in the form oS a Star. This Salt is grey ; and it is im- poffible to obtain it of a whiter colour by any repetition of So- lutions and crystallizations. It is an acid which effervefces with chalk, and reddens the infufion of turnfole. Half an ounce of this fait is foluble in an ounce and an half of boiling water, or twelve ounces of cold water. Boiling fpirit of wine diffolves its own weight pf this acid; but cold fpirit diffolves only one fourth. This fait is inflammable in the fire. It melts, and leaves a coal of difficult incineration. When this acid is diftilled in a retort, it becomes at firft fluid, gives out an acid phlegm, but no oil; and, towards the end, a white Sublimate rifes, which attaches itfelf to the neck of the retort, and remains fluid as long as it is hot, but afterwards crystallizes. Much coal is Sound in the retort. The Sublimate has ncarlv the tafte and fmell of acid of benzoin, is as foluble in water.as in Spirit'of wine, reddens the infufion of turnfole, and precipitates.metallick Solutions with their different colours, and iion bkek." ' Difcovery of Ptufflan Blue. 35' The folution of the Salt of the nut-gall, poured into a fo'uti^n •f gold, renders it of a dark green ; and precipitates a bro v.i powder, which is gold revived. The Solution of filver becomes brown ; and at length depofites a grey powder, which is revived filver. The folution of mercury is precipitated of a yellow orange colour. The folution of copper affords a brown precipitate. The folution of iron becomes black The folution of the acetite of lead is precipitated white. This fait is changed into the oxalick acid, if the nitrick acid be diftilled from it. The bafis of ink confifts of a folution of iron by the gallick acid. To make good ink, take one pound of nut-galls, fit ounces of gum arabick, and fix ounces of green copperas, with four pints of common water. The nut-galls muft be bruifed, and infufed for four hours without boiling. The pounded gum muft be firft added, and fuffered to diffolve ; and laftly, the cop- peras, which immediately converts the fluid to a black colour. Lewis, of the Royal Society of London, made many refearches on this Subjea ; but he always returns to the Sorementioned fubftances. Powdered Sugar is Sometimes added, to render th© ink Shining. 5. The vegetable acid likewiSe diffolves iron with facility- It is this which holds the metal fufpended in vegetables ; and it may be precipitated from wine in the form of aethiops, by the means of alkalis. 6. Cream of tartar, or the acidulous tartrite of pot-afh, likewife diffolves iron ; and the various degrees of concentration of this folution forms the foluble martial tartar, the aperitive extraa of Mars, and the balls of Nancy. 7. The folution of iron, by the oxalick acid, affords prifmat- ick cryftals of a greeniffi yellow colour, and a fomewhat aftrin- gent tafte, foluble in water, and eiflorefcing by heat. 8. Iron diffolved by the pruflick acid, forms Pruffian blue, or the prufliate of iron. A Singular mistake gave rife to the difcovery of this fubftance. Diefbach, a chemift of Berlin, being defirous of precipitating a decoaion of cochineal with fixed alkali, borrowed of Dippel an alkali upon which he had feveral times diftilled animal oil ; and as the decoaion of the cochineal contained fulphate of iron, the liquor immediately afforded a beautiful blue. The experiment being repeated was followed with fimilar refults ; and this col- our became an objea of commerce, under the name of Pruffian Blue. 352 theory of Pruffian Blue. Pruffian blue was announced in the Memoirs of the Acade- my of Berlin in the year 1710, but without any account of the procefs, which was kept a Secret until other chemifts difovered it. The procefs was rendered pubiick in the year 1724, in the Philofophical Tranfaaions, by Woodward ; who declared that he had received it Srom one of his friends in Germany. To make Pruffian blue, four ounces of alkali are mixed with the fame weight of dried bullocks blood, and the mixture expo- fed in a crucible, which is covered in order to flifle the flame ; the fire is kept up until the mixture is converted into a red-hot coal. This charcoal is thrown into water which is afterwards filtered, and concentrated by evaporation. The liquor is known by the name of the Phlogifticated Alkali. On the other hand, twoouncesof the fulphate of iron, andfour ounces of the fulphate of alumine are diffolved in a pint of water. The two folutions are mixed and a bluiffi depofition falls down, which is rendered ftill more intenfely blue by waffiing it with muriatick acid. Such is the procefs ufed in chemical laboratories ; but in the works in the large way another method is followed. E- qual parts of the rafpings of horns, clippings of fkins, or Other animal fubftances, are taken and converted into charcoal. Ten pounds of this coal are mixed with thirty pounds of pot-afh, and the mixture is calcined in an iron veffel. ASter twelve hours ignition, the mixture acquires the form of a Soft pafte, which is poured out into veffels of water. The water is then filtered ; and the Solution mixed with another, confifting of three parts of alum, and one the fulphate oS iron. I have likewiSe made Pruffian blue by calcining and burning in the Same veffel equal parts of the Shavings of horns and tar- tar. I received the animal oil and the ammoniack, afforded by the calcination of thefe fubftances in large cafks, which commu- nicated with each other, and formed an apparatus after the man- ner of Woulfe. It has likewife been obServed that the tips of the thyme, the fun-flower, and feveral other vegetable Subftances, when treated with alkali, communicate to it in a certain degree, the property of precipitating iron oS a blue colour. Much reaSoning has been exhibited on the etiology oS this phenomenon. Meffrs. Brown and Geoffroy confidered Pruffi- an blue as the phlogifton of iron, developed in the lixivium of blood. The abbe Menon imagined that the colour of iron was blue, and that the phlogifticated alkali precipitated it in its nat- ural colour. Mr. Macquer refuted the opinion of his predeceffors in the year 1752 ; and propofed a fyftem, in which he confiders Pruf- Analyfis of Pruffian Blue. £53 fun blue as iron fuperfaturated with phlogifton. This Skil- ful chemift proved that the blue is not Soluble in any reSpea in acids; and that the alkalis are capable of diffolving the colour- ing matter of the Pruffian blue, and of becoming faturated with it to fuch a degree as to be no longer capable of effervefcing. Mr. Sage affirmed that the iron was faturated with the phof- phorick acid ; and the celebrated Bergmann likewife fufpeaed the exiftence of fome animal acid, as is proved by his notes on the leffons of chemiftry of Scheffer. But it was referved to the celebrated Scheele to convert thefe fufpicions into certainty. He has proved that the lixivium of blood, expofed for a cer- tain time to the air, lofes the property of precipitating iron of a blue colour ; and he has fhewn that this circumftance depends on the carbonick acid of the atmofphere, which difengages the colouring part. By adding a fmall quantity of fulphate of iron to this lixivium, it is no longer changed in confequence of its re- maining in the carbonick acid. By boiling this lixivium upon an oxide of iron, it is likewife no longer capable of change in the carbonick acid. The iron has therefore the property of fixing and retaining the colouring principle ; but it is neceffary that it Should not be in the ftate of oxide. Pruffian blue, treated in the way of diftillation with the ful- phurick acid, permits a fluid to efcape that holds the pruffick acid in folution, which may be precipitated upon iron. The proceffes of Scheele, to obtain this acid in a ftate of pu- rity, confift in putting two ounces oS pulverize! Pruffian blue into a glaSs cucurbit, with one ounce oS red precipitate, and fix ounces oS water. This mixture is to be boiled Sor Some min- utes, continually ftirring it. It then affumes a yellow colour In- clining to green. The fluid being filtered, two ounces oS boil- ing water are to be thrown on the refidue. This liquor is a prufliate oS mercury, which cannot be decompoSed either by alkalis or acids. The Solution is then poured into a bottle, in which an ounce oS newly-made filings of iron is put: three gros of concentrated fulphurick acid are to be add«^d, and the whole agitated ftrongly for feveral minures. The mixture be- comes perfeaiy black by the reduaion of the mercury ; the li- quor lofes its mercurial tafte and exhibits that of the colouring lixivium. After fuffering it to Hand at reft for a time, it is de- canted, put into a retort, and diftilled by a gentle fire. * The colouring principle paffes firft, becaufe more volatile than water. The operation muft be put an end to, as foon as one quarter of the liquor has paffed over. As this produa contains a fmall quantity of fulphurick acid, it may be cleared of it by re-diftil- ling it from pulverized chalk by a very gentle, fire. The 2...W 354 , Analyfis Of Pruffiatt Acid. pruffick acid then comes over in a ftate of the greateft purity. Scheele recommends that the veffels be well luted, becauSe the acid would otherwiSe eScape on account of its great levity. It is even of advantage to put a fmall quantity of water into the receivers, to abSorb the acid ; and it would likewiSe be very pro- per to Surround them with pounded ice. This acid has a particular Smell which is not diSagreeable j and its tafte is fweet. It does not redden blue paper ; but renders the Solutions of foap and of the fulphure of alkali turbid. Mr. Weftrumb pre- tends that the pruffick acid is the fame as the phofphorick ; for he obtamed fiderite from Pruffian blue, and formed animal earth by mixing the lixivium of blood with a Solution of calcareous earth. The folution of iron in the pruffick acid affords Pruffian blue. We are indebted to Mr. Berthollet for a very interesting feries of experiments upon the pruffick acid, and its combinations. The oxide of iron is capable of exifting in two different ftates in combination, with the pruffick acid. If the oxide predomi- nates, the combination is yeilowifh ; but if its proportion be lefs, the produa is Pruffian blue. All the acids are capable of dif- folving the portion or Surplus of oxide which Conftitutes the difference between the firft and fecond combination. The prufliate of pot-affi contains oxide of iron. If an acid be poured in, this oxide is diffolved, and is precipitated by dou- ble affinity in the form of Pruffian blue. The prufliate of pot- affi made by a gentle heat, afterwards evaporated to drynefs, then re-diflblved and filtered, no longer affords the blue upon the addition of acids. It cryftallizes in fquare plates with their edges cut flantways, forming oaahedrons, whofe two oppofite pyramids are truncated. This folution of the prufliate of pot- affi, when mixed with the fulphurick acid, depofites Pruffian blue, if it be expofed to the folar light, or to a ftrong heat. In thefe proceffes the prufliate of alkali may be entirely decompof- ed ; the prufliate of iron when precipitated by the aaion of the alkaline prufliate, carries down with it a notable proportion of alkali, of which it may be cleared by wafhings, which contain the alkaline prufliate. It is the farrfe with regard to precipita- tions by the pruffiates of lime and ammoniack. The prufliate of mercury cryftallizes in tretahedral prifrrrs, terminating in quadrangular pyramids, whofe planes anSwer to the angles of the prifms. Iron in Its metallick ftate decompo- fes the prufliate oS mercury, and deprives it both oS its oxigene and its acid. The oxide of mercury likewife decompoSes the prufliate oS iron and Seizes Its acid. The prufliate of mercury is but imperfeaiy decompofed by the fulphurick and muriatick Analyfis of Pruffian Acid. 355 acids. TheSe acids Sorm triStiles, or triple Salts with it. The precipitate of the nitrate oS barytes by the pruffick acid, is not the compound which Bergmann fuppofed it to be, but is mere- ly a trifule. > . . The pruffick acid readily precipitates alumine from its- nitrick folution ; the alumine neverthelefs yields its pruffick acid to iron. The oxigenated muriatick acid, when mixed with the pruffick acid, is again converted to the ftate of common muriatick acid: the pruffick acid affumes a more lively fmell, becomes more vol- atile, is deprived of its affinity to alkalis and lime ; it precipi- tates iron of a green colour ; and the green becomes blue if the precipitates be expofed to light, or if it be treated with the ful- phureous acid. The pruffick acid, impregnated with the oxigenated muriat- ick acid, and expofed to light, affumes the fmell of an aromat- ick oil, is colfeaed at the bottom of the water in the form of an oil which is not inflammable, and rifes in vapour by a gentle heat. By repeating this procefs it may be totally decompofed ; and then this fpecies of oil becomes concrete, and is reduced in- to cryftals. The acid appears to have undergone a partial combuftion in this operation ; at leaft the light and the fulphureous acid do not reftore it but by depriving it of oxigene. The oxigenated pruffick acid, mixed with lime or a fixed alkali, becomes totally decompofed. Volatile alkali is difengaged ; and if the alkali was very cauftick, fuch as the alcohol of pot-affi, it becomes ef- fervefcent. The pruffick acid of Scheele is only decompofed in part by this procefs; whence Mr. Berthollet concludes that it is com- pofed of hydrogene, nitrogene, and carbone. Thefe experiments do not prove that oxigene exifts in this acid. The water affords that which enters into the carbonick acid, produced by the diftillation of the pruffick acid. Pruffian blue takes fire more eafily than Sulphur, and detonates ftrongly with the oxigenated muriate of pot-affi. The prufliate of mer- cury detonates ftill more ftrongly with the nitrate of mercury. The gas of thefe detonations has not yet been colleaed. The pruffick acid, combined with alkali and the oxide of iron, cannot be feparated by any acid without intervention of heat or light*; and when it is difengaged, it is no longer capable of feparating iron from the weakeft acid, unlefs it be in the way of double affinity. Mr. Berthollet thinks that the elaftick ftate of this acid diminiffies this affinity ; and that it is neceffary, in order ihat it may eafily enter into combination, that it ffiould have loft 35°" Habitudes of Iron. fome of its fpecifick heat. It is this which renders the oxige- nated acid fo feeble. Pruffian blue afforded me, by diftillation, in the ounce, one gros twenty-four grains of ammoniack, thirty-fix grains of the carbonate of ammoniack, four gros twelve grains of oxide of iron, or alumine, and one hundred and Sixty-four inches of hydrogen- ous gas burning with a blue flame. The ammoniack comes over in combination with a Small quantity of the colouring principle, which it takes up, and holds in folution : the fulphurick acid renders this vifible. Ammoniack heated upon Pruffian blue decompoSes it, by Seiz- ing the colouring matter. Lime-water digefted upon Pruffian blue diffolves the colour- ing principle by the affiftance oS a gentle heat ; the combination is rapid, and the water acquires a yellow colour. By filtration, the liquor paffes of a fine bright yellow, no longer converts fyr- up of violets to a green, and is no longer precipitated by the car- bonick acid. It appears to be completely neutralized, and af- fords an exceedingly fine blue, when poured into a folution of the Sulphate of iron. The prufliate of lime has been propofed, by Meffrs. Fourcroy and Scheele, as the moft accurate means of* afcertaining the prefence of iron in any mineral water. The pure fixed alkalis immediately difcolour Pruffian blue in the cold. This combination produces heat ; and the pure alka- lis ought to be preferred, to the carbonates of alkali in experi- ments of this nature. Magnefia likewiSe Seizes the colouring matter of Pruffian blue ; but much more weakly than lime-water. A. mixture of equal parts of fteel filings and nitrate of pot-afh. thrown into a crucible ftrongly ignited, detonates at the end of a certain time, with the difengagement of a confiderable quaiv tity of very bright fparks. The refidue, when wafhed and fil- tered, affords an oxide of iron of a yeilowifh colour, known by the name of Zwelfer's Saffron of Mars. Iron decompofes the muriate of ammoniack very well. Two gros of fteel filings, and one gros of this fait, afforded Mr. Buc- quet, by diftillation in the pneumato-chemical apparatus over mercury, fifty-four cubick inclies of an aeriform fluid ; half of which was alkaline gas, and the other half hydrogenous gas. This decompofition is founded on the ftrong aaion of the muriatick acid of iron. One pound of the muriate of ammoniack in powder, and one ounce of fteel filings, fublimed together, form the Martial flow-. ers, or Ens Martis. Thefe flowers confift merely of the muri- ate of ammoniack, coloured, and rendered yellow by arf oxide of iron. Tin Plates. Ufes of Iron. 357 The oxide of iron decompofes the muriate of ammoniack much better. This is an effea of double affinity. The am- moniack which rifes is fometimes effervefcent. A mixture of good filings of fteel and fulphur, moiftened with a fmall quantity pf water, becomes heated in the courfe of feveral hours. The water is decompofed, the iron rufts, the fulphur is converted into acid, the hydrogenous gas of the wa- ter exhales, and the heat is fometimes fufficient to fet the mixture on fire. This phenomenon conftitutes the volcano of Lemery. There is the ftrongeft analogy both in the phenomena and effeas of the infla'mmatiqn of this volcano, and the decompofi- tion of pyrites. Sulphur combines eafily with iron by fufion, and then forms a true martial pyrites. Iron may be alloyed with feveral metallick fubftances; but the only alloy which is ufed in the arts is that which it contraas with tin, to form white iron, or tin plates. To form tin plates (commonly known by the name of Tin in England) the fofteft iron is chofen, which is reduced into very thin plates. Care is taken to polifh or clean the furface very well; and this is done in feveral ways. The pieces are rub- bed with fand-flone, and afterwards kept for three times twenty- four hours in water, acidulated by the fermentation of malt, turning them from time to time. They are afterwards cleaned, dried, and are then ready for tinning. Sal ammoniack is like- wife ufed in fome manufaaories. For this purpofe the plates are difpofed in a chamber, in which a certain quantity tf fal ammoniack is volatilized. The fait forms a covering over the whole furSace of every plate, and poffeffes the double advant- age of clearing it from ruft, and affording the coaly principle neceffary to prevent the calcination of the metal. When the iron is well cleared, the plates are plunged verti- cally into a bath of tin, whofe furface is covered with pitch or tallow. They are turned in the bath; and when taken out they are wiped with faw-duft or bran. rl he ufes of iron are fo very extenfive, that there are few arts which can be praaifed without it. It is with juftice con- fidered as the foul of all the arts. Some of its ores are ufed in their native ftate ; fuch as the haematites, which is made in- to burnifhers. The fulphate of iron is the bafis of all black colours, inks, Sec. The ochres are ufed by painters, under the name of Umber • and the brown red has the moft extended ufe. With us (in France) it is applied to give a colour to brick pavements to paint our doors and windows, to fmear our calks, and tg fecure {hem from decay and infeas in fea voyages. 358 Properties of Copper. Caft iron is ufed to make boilers, chimney-grates, hesrths, pots, &c. The inftruments of agriculture are made of this metal: fteel is ufed not only as fteel; but its hardnefs renders it proper to cut and work the other metals. The magnetical property of iron has led to the diScovery of the mariner's compafs; and this metal, if it were produaive of no other advantage to mankind, would on that account be en- titled to their greateft attention. Pruffian blue is an agreeable colour, greatly efteemed, and much ufed. Iron likewife furnifhes the art pf medicine with remedies. It is the only metal which is not noxious; and it has Such an analogy with our organs, that it appears to conftitute one of the elements of the human frame. Its effeas in general confift in ftrengthening the ftomach; and it appears to poffeSs the proper- ty of paffing m the circulation under the form of aethiops. The valuable experiments of Mr. Menghini, published in the Me- moirs of the Inftitute of Bologna, have proved that the blood of perfons who take martial remedies is thicker, and contains more iron. Mr. Lorry obferved that the urine of a Sick perSon, to whom he adminiftered iron in a ftate of extreme divifion, was manifeftly coloured with the nut-gall. CHAPTER XL Concerning Copper. COPPER is a reddiffi metal, hard, elaftick, Sonorous, and affording a diSagreeable Smell by friaion. It tafte is ftyptick, and naufeous. One cubick foot of copper weighs five hundred, and forty-five pounds. The fpecifick gravity of caft copper not hammered is 7.7880.—Briffon. The alchemifts diftinguiffied this metal by the name of Venus, on account of the facility with which it unites and is alloyed with other metals. It may be reduced into very thin leaves, and drawn into very fine wire. The tenacity of this metal is fuch, that a wire of one tenth of an inch in diameter, is capable of fupporting a weight of two hundred and ninety-nine pounds four Ounces*, without breaking. This metal is capable of affeaing a regular form. The abbe Mongez obferved it in folid quadrangular pyramids, Sometimes inSerted into each other. Ores of Copper. 35$ Copper is found [in various forms in the bowels of the earth. 1. Native copper.—This copper exifts fometimes in leaves in a gangue of quartz. It is likewife found in compaa maffes at Japan. There is one of thefe pieces in the royal cabinet, which weighs ten or twelve pounds. Native copper is ufually diffemiriated in a browniffi martial earth, fufceptible of a poliffi. When this ore is rubbed with a flint, the traces appear of a beautiful copper-colour. Ores of this kind are Sound at Kaumfdorf in Thuringia—Sage, Analyfe Chimique, t. iii. p. 205. We have likewiSe Sound native copper at Saint Sauveur. It has the Sorm oS nodules reSembling ftalaaites. Moft of the na- tive coppers appear to be Sormed by cementation, or by the pre- cipitation of this metal diffolved in an acid, and thrown down by martial falts. ' Mr. Sage thinks that this metal may likewife be precipitated from its folutions by phofphorus. To effea, fays he, the pre- cipitation of copper by phofohorus, twelve grains of this metal are to be diffolved in half a gros of nitrick'acid. The folution muft be poured into half a pint of diftilled water, into which a cylinder of phofphorus, two inches long, weighing forty-eight grains, muft be plunged. The furface becomes almoft immedi- ately black, and is covered with particles of copper poffeffing the metallick colour and brilliancy. At the end of feveral days, oaahedral cryftals are feen, whofe infertions into each other produce elegant dendrites ; and at the end of ten days, the twelve grains of copper are completely reduced, as is proved by pouring ammoniack into the water. If it do not exhibit a blue colour, it is proof that the fluid contains no copper. 2. Copper mineralized by fulphur forms the yellow ore of cop- per. This ore is of a golden colour, and the ignorant are often deceived by its flattering appearance. It contains a larger quantitv of copper in proportion as the fulphur is lefs in quan- tity, and gives fewer fparks with the Steel. It fometimes cryf- tallizes in beautiful oaahedrons. I poffefs two fpecimens cov- ered over with trihedral pyramids of near an inch long, and be- tween four and five lines in diameter at the bafes. When the fulphur is fo abundant that the proportion of cop- per will no longer pay for the working, the ore is called Macar- Site. The marcafite cryftallizes in cubes or in oaahedrons, which eafily effloreSce. The yellow copper ore is found in various ftates according to the courfe of its decompofitior:. The firft imprtffion of hepatick 3°o Ores of Copper. vapours colours the furface in a thoufand Shades, in which ftate it is known by the name oS Peacocks Tail, Pigeons Neck, &c. The laft degree oS alteration oS this ore, effected by the Sim- ple diSengagement oS Sulphur, Sorms the hepatick copper ore. The yellow colour is then converted into an obScure brown col- our : this ore appears then to contain no other principles but water, copper, and iron, which laft is always more or leSs abun- dant in theSe ores. The yellow copper ore Sometimes Sorms Sulphate of copper in its decompofition. This fait is diffolved in water, and forms fprings more or leSs loaded with it, Srom which the copper may be obtained by cementation. Old iron is thrown into the wa- ter ; the copper is precipitated, and the iron takes its place. In this way it is obtained in Hungary, and we might ufe this econ- omical procefs in feveral parts of our province. I have Stalac- tites in my colfeaion, fent me from Cevennes, which are col-, oured blue by a very confiderable quantity of copper. In Ge- vaudan,-at half a quarter of a league from St. Leger de Peyre, feveral fprings of water impregnated with copper are found, which run into a valley. The inhabitants of this canton drink a glafs of the water occafionally as a purgative. The fkefetons of animals are fometimes found in copper mines penetrated with that metal. Swedenburg has given an engraving of the figure of a fkeleton of a quadruped taken out of a copper-mine and coloured by that metal. In the royal cab- inet there is a human hind, green at the extremity of the fin- gers, the mufcles of which are dried and greeniffi. According to the report of Mr. Level, conful of mines, there was found at Fahlun in Sweden, in the great copper mine, a human carcafe, which had remained there forty years, with the flefh and bones entire, without corruption, and without emitting any fmell. The body was clothed and entirely incrufted with vitriol.— Aaa Literaria Suec. tri. i. anno 1722, p. 25a. The turquoife ftones are merely bones coloured by the oxides of copper. Mr. De Reaumur, in the year 1725, gave an ac- count to the Academy of the turquoifes found in Lower Languedoc. The colour of the turquoife. frequently becomes converted into green, which depends on the alteration of the me- tallick oxide. The turquoife of Lower Languedoc emits a fe- tid fmell by the action of fire, and is decompofed by acids. The turquoife of Prnffia emits no fmell, and is not attacked by acids. Mr. Sage fufpeaed that the offeous part is agitized in thefe laft. 3. Grey copper ore.—The copper is mineralized by arfenick. It has a grey colour, and an appearance nearly vitreous. It ufu- ally contains fziver; and., when wro-jght to extraa this precious Ores of Copper. 361 rnetil, it is called the Grey Silver Ore. It affeas a tetrahedral. form ; and arfenick is the moft predominant of its principles." 4. The grey antimonial copper ore.—This differs from the for- mer, becaufe it contains'fulphur and antimony, and is much more difficult to be wrought. When expofed to the fire, it be- comes as fluid as water; the fulphur is volatilized with the an- timony and the arfenick. The refidue of the torrefaaion is a mixture of tile antimony and copper, and fometimes it contains filver likewiSe. 5. Copper ores, in their decompofition, are reduced to a more or lefs perSea ftate of oxidation. The carbonick acid frequent- ly unites to the metal, and becomes the mineralizer. This fub- ftance is known by the name of Mountain Blue, Azure of Cop- per, Mountain Green, Malachite. A. The azure of copper cryftallizes in rhomboidal tetrahe- dral prifms, rather flattened, terminating |in dihedral fummits : thefe cryftals are of the moft beautiful blue ; they are frequent- ly altered by expofure to the air, and become converted into malachite. Mr. Sage has imitated the azure, both in the form and col- our, by diffolving copper, in the cold, in water Saturated with Carbonate of ammoniack. When the azure of copper is of a lefs brilliant colour, and in the pulverulent form, it is called Mountain Blue. B. The malachite cryftallized in oaahedrons has been found in Siberia. This ore is frequently ftriated,' formed into fmall tufts of a Silky appearance, or in very clofe parallel fibres. The malachite is frequently covered with protuberances. This fig- ure appears to announce that it has been formed in the fame manner as the ftalaaites. Mountain green differs from the malachite only in its pulve- rulent form, and the mixtures which alter it. The alterations of the copper ores, and native copper likewife, produce a cupre- ous oxide, which bears the name of Red Copper Ore. The mine of Predanah, in the county of Cornwall, has afforded the fineft fpecimens of red copper ore. The metal is nearly in the metallick ftate, and has the*form of oaahedral cryftals. The granular red copper ore differs from this only in its figure. It fometimes has a brown martial earth for its gangue. The azure, the malachite, and the red copper require no oth- er procefs but mere fufion with coal to convert them into metal; the other kinds require to be cleared of their mineralizer by tor- refaaion, and afterwards to be fufed with three parts of black flux. To affay a fulphureous copper ore, Mr. Exchaquet propofes to make two gros of the crude ore, and one of the nitrate of pot- 2...X S6'2 Working of Copper Miner. afh j which, aSter pulverization, are to be detonated in an ignit- ed crucible. The matter becomes hard after the detonation ; upon which the fire is to be increaSed and kept up, in order that the Sulphur may be diffipated. The fire is then to be ftill more ftrongly urged, until the ore enters into fufion ; and a mixture of half an ounce Of tartar, one quarter of an ounce of Salt, and a Small quantity of charcoal, is to be added in equal portions. . An effervefcence takes place at each projeaion of the mixture. The fire is then to be ftill more Strongly raiSed, and the crucL ble covered, arid kept in this State for half an hour, in order that the copper may flow into a mass. In this way a very mal- leable button of copper is obtained. The working of copper ores varies according to their com- pofition. But, as the fulphureous ores are moft commonly wrought, we Shall confine ourfelves to the procefs which is moft fuitable to their nature. The metal is firft picked or Sorted ; afterwards pounded in a mill, and waffied, to Separate the gangue, and other Soreign Sub- ftances ; it is then roafted to drive off its mineralizer; and af- terwards SuSed in the blaft Surnace. The reSult of this firft fu- fion is black copper : which is again fufed in the. refining fur- nace, to diffipate all the fulphure which has withstood the pre- ceding operations. When it is very pure, it is poured into a broad veffel, or reft ; a fmall quantity of water is thrown on its fur- face, which, being by that means cooled, feparates from the reft, and is taken up. This is the copper in rofettes, which is taken to' the hammer to be beat into proper form. • The feveral opera- tions are different in various places. In fome countries, the ore is roafted as often as eight times •, in others one or two are fuf- ficient ; and in feme places it is not roafted at all. This varie- ty depends—i. On the variations of praaice: thofe who roaft but little, employ more time and care in the fufion and refining. 2. On the nature of the ore : when it is rich in iron, the roaft- ings are neceffary to difpofe this metal to fufion. The method of roafling is likewife prodigioufly varied. Pie- ces of the mineral are fometimes heaped up on a bed of combuf- tible matter, and in this manner the calcination is performed j but, when this ore abounds with fulphur, it may be extraaed by the ingenious procefs ufed at St. Bell, and defcribed by Meffrs* Jars in their excellent work. The fufion is commonly performed in the blaft furnace; but at Briftol, in England, the ore is roafted in a reverberatory Sur- face, and SuSed into black copper. The refining Surnace conftruaed at St. Bell, by Meffrs. Jars, i.vtfpXS to rne to be one of the beft. They have published ax* Properties of Copper. 363 excellent defcription of it, which maybe confulted in their Min- .eralogical Travels. The refining of copper confifts in depriving it of the fulphur and iron wrhich it may ftill retain. The fulphur is diffipated by fire, and bellows properly direaed ; and the .iron is feorified by the affiftance of fome pounds of lead fufed with the copper. The Skilful mineralogilts whom I have juft quoted, make ufe of a reverberatory furnace, lined with char- coal ; and fufe and fkum their copper, without ufing lead. When the copper contains a fufficient quantity oS filver to ad- mit oSextraaion, the following procefs is ufed :—1. Seventy- five pounds of copper are fufed with two hundred and feventy- five of lead. The alloy is caft into flat pieces, which are called Loaves of Liquation. 2. Thefe loaves are expofed to a heat fufficient to fufe the lead, which carries the filver with it, and leaves the copper, which on account of its being more difficult to fufe, retains the original form ef the loaves; and is every where penetrated by the interftices through which the fufed metal made its efcape ; thefe are called Dried Loaves of Liqua- tion. 3. They are carried into a fecond furnace, where they are expofed to a ftronger heat, to deprive them of the fmall quantity of lead which they ftill retain. 4. The lead is after- wards taken to the cupel, where it is fufed, and feparated from all the filver it had taken up. Copper is altered by long expofure to the air. Its Surface ■becomes covered with a greeniffi coating, which is very hard, and known to the antiquarians under the name of Patin. This is the feal which attefts the antiquity of ftatues and -»models covered with it. Copper, expofed to the fire, becomes blue, yellow, and at laft violet. It does not flow until It is ftrortgly ignited. When in contaa with the coals, it gives a blue greeniffi tinge to the flame ; and if it be kept a long time in fufion, part of it is volatilized. When copper is heated in contaa with air, it burns at its furface, and becomes changed into a blackiffi red oxide. This oxide may be feparated by Striking the plate which has been ignited, or by plunging it in water. When the oxide has been pounded, and moft ftrongly calcined, it affumes a brown red colour, and may be converted into a glafs of a brown colour by a more violent heat. * 1. The fulphurick acid only aas on copper when concen- trated, and very hot. It then diffolves it, and eafily affords blue cryftals of a rhomboidal form. The fulphate of copper is knOwn .in commerce by the name of Blue Vitriol, Cfprixn Vitripl, Blue Copper, Sec. 3 6*4 Properties of Copper, Two methods are ufed to make the fulphate of copper which is met with in commerce. The firft confifts in calcining the cupreous pyrites, and caufing them to efflorefce, in order to de- yelope the fidt, which is then extraaed by lixiviation. The Se- cond confifts inSorming this pyrites artificially, burning it, and lixiviating it, to extraa the Salt. This Salt poffeffes a very ftrong ftyptick tafte. It is eafily fu- fible by heat, which diffipates its water of cryftallization, and changes its colour to a bluifli white. The Sulphurick acid may be extraaed by a very ftrong fire. Lime and magnefia decomr pofethis fait ; and the precipitate is of a bluiffi white colour. If it be dried in the open air, it becomes green. Ammoniack likewife precipitates the copper in a whitifh blue ; but the pre- cipitate is diflblved nearly the Same inftant that it is Sormed ; and the reSult is a folution of a beautiful blue colour, known by the name of Aqua Celeftis. This fait contains in the quintal thirty pounds acid, forty- three water, and twenty-feven copper. 2. The nitrick acid attacks copper with efferveScence, at the fame time that it becomes decompofed, and emits abundance of nitrous gas. When it is propoSed to obtain this gas by the ac- tion of the acid upon the copper, it is neceffary to have the pre- caution of weakening the acid, and to prefent the copper in pieces of confiderable magnitude. If thefe circumftances be not attended to, the acid attacks the metal with Such violence, as Suddenly to emit a prodigious quantity ( f gas ; immediately aSter which an abSorption takes place, and the water of the jar paffes into the bottle. In this cafe ammoniack is formed. The diluted nitrick acid perSeaiy diffolves copper : the Solution is blue. IS it be fpeedily concentrated, no other reSult is obtained but a magma without cryftals ; but iS it be leSt expofed to the air, it affords cry(lals in long parallelograms. By leaving a fo- lution of this kind to fpontaneous evaporation, I have obtained rhomboidal cryftals, which, inftead of being blue, as they are ufually deScribed, are white. They decrepitate upon the coals, emit a red gas by mere heat, and nothing remains but a grey oxide. 3. The muriatick acid does not diffolve copper unleSs It be boiling and concentrated ; the Solution is green, and affords priSmatick cryftals of confiderable regularity when the evapora- tion Is flow. This muriate is of an agreeable grafs-green col- our ; its tafte is cauftick, and very aftringent ; it fuSes by a gentle heat, and congeals into a maSs ; in which the acid is So adherent, that a very ftrong fire is required to diSengage it. It is very deliqueScent. Ammoniack does not diffolve the oxide of Formation of Verdigris. go"* this muriate with the fame facility as it does that of the other cupreous falts. This obfervation was made by Mr. De Four- croy ; which I think may be explained from the circumftance that the muriatick acid Suffers the copper to be precipitated in the metallick form, inftead of giving out a portion of its oixgene which would facilitate the aaion of the alkali. 4. The acetous acid, when made to aa either hot or cold up- on copper, only corrodes it, and produces the fubftance known in commerce under the name of Verdigris. The verdigris which is moft ufed in the arts has been long fabricated at Mont- pel Her exclufive!y. The prejudice which prevailed, that the cellars oSthis city alone were proper Sor this operation, preferv- pd this commerce till lately in its han^s. But the progreSs of information has Succeffively put it in the power oS other coun- tries to partake in this manufaaure. The procefs ufed at Montpellier confifts in fermenting the refufe oS grapes with Sour wine.* This refufe is afterwards laid in alternate ftrata, with plates of copper fix inches long and five broad. In this ftate they are left for a certain time ; after which they are taken out, and placed edgewife in a cellar, where they are fprinkled with Sour wine : in this fituation the verdi- gris Swells up ; and is aSterwards Scraped off, put into Sacks of leather, and exported to foreign countries. Ready-made vinegar is ufed at Grenoble, and the plates of copper are Sprinkled with it. The verdet or verdigris of Grenoble contains one Sixth lefs of copper; the vinegar which is obtained is flronger and more a- bundant. It has not the empyruematick fmell of that of Mont- pellier. The copper is therefore partly diffolved in the verdet of Grenoble ; becaufe it has been firft reduced into an oxide by the impreffion of the vinegar, and afterwards attacked by the fubfequent affufion pf the fame acid. It is therefore an acetate of copper. The oxides of copper, diffolved in vinegar, Sorm a Salt known by the name oS Cryftallized Verdigris, Cryftals oS Venus, Ace- tate oS Copper. To obtain this Salt, the vinaffe or four wine is diftilled ; and this weak vinegar boiled on the verdigris. The folution is then conveyed into a boiler, where it is concentrated until a pellicle appears. Sticks are then plunged in the bath ; and at the end of a certain number of days the fticks are again taken out, cov- ered with rhomboidal cryftals of a blue colour. Thefe clufters * Vinaffe. 3<5o" Habitudes of Copper. of cryftals, weighing each from four to fix pounds, arc wrapped up in paper, and diftributed for Sale. The vinegar may be diSengaged by diftillation from theSe cryftals ; and the refidue is a cupreous oxide, which poffeffes the charaaers oS pyrophorus. Vinegar, diftilled on manganeSe, diffolves copper ; whioh proves that it has taken up oxigene. The acetick acid, or rad- ical vinegar, differs from ordinary vinegar, in containing a great- er quantity of oxigene ; and it is this oxigene which renders it proper to diffolve copper in the metallick ftate. The acetate of .copper may likewife be formed by decompofing fait of Saturn, or fugar of lead, by.the fulphate of copper. The fulphate of lead falls down : and the folution when concentrated, affords a cupreous acetate. 5. The pure fixed alkalis, digefted in the cold with filings of copper, become of a blue colour ; but ammoniack diffolves it much more fpeedily. I put copper filings into a bottle with very cauftick ammoniack, and kept the bottle Slopped for two years ; the copper was deprived of its colour, and became Sim- ilar in appearance to a grey clay ; whereas a fimilar veffel, in which I had placed the Same mixture, but leSt open, Soon afford- ed me very Small blue cryftals ; and the whole concluded by affording only a hard Stratum of green matter, refembling mal- achite. Copper is precipitated Srom its Solutions by iron. For this purpoSe nothing more is required than to leave the iron in one of the folutions oS the other metal, which need not be Strong. The phenomenon may be rendered very Surprising, by pouring the Solution of the fulphate oS copper upon the clean SurSace of a piece of iron ; for this furface inftantly becomes covered wiih copper. The copper obtained by this means, is known by the name of Copper Cementation. This precipitation of one metal by another, has given rife to a belief that the iron was converted into copper : and I could, from my own knowledge, mention the names of individuals who have been impofed on by this phenomenon. Copper mixes with moft oS the metals ; and Sorms— 1. With arSenick, the white tomback. • 2. With biSmuth, an alloy of a reddiSh white colour, with cubick facets. 3. With antimony, a violet-coloured alloy. 4. It may be combined with zinc by fufion, or by cementa- tion with lapis calaminaris. By the firft procefs, Similor, or the Manheim gold, is obtained ; the produce of the fecond is brafs. Habitudes of Copper. 3*7 5. Copper, plunged in a Solution oS mercury, affumes a white colour, which ariSes Srom the mercury which is displaced by the capper. 0. Copper is eafily united with tin; and on this depends the art oS tinning ; Sor which purpoSe it is neceffary to clean the Sur- face oS the metal perSeaiy; becauSe the oxides do not combine with the metals. This firft obfea is accomplifhed by rubbing the metals intended to be tinned with the muriate of ammoni- ack, or by Scraping it effeaually ; or even by palling a weak acid over its whole Surface. After this operation the tin is applied by fufing it in the veffel intended to be tinned, then Spreading it about with old rags rolled up; and the oxidation oS thefe met- als is prevented by means of pitch. Copper, SuSed with tin, Sorms bronze, or bell-metal. This alloy is more brittle, whiter, and more Sonorous, in proportion fo the quantity oS tin that enters into its combination : it is then uSed to make bells. When it is intended to be applied to- the purpoSe of cafting Statues, or forming great guns, a larger proportion of copper is ufed; becaufe in this cafe folidity is one of the firft requifites. 7. Copper and ironcontraa very little union. 8. Copper, alloyed with filver, renders it more fufible; and thefe two metals are combined to form folders. Hence it is that verdigris is occafionally obferved in pieces of filver, at thofe parts where joinings have been made by means of the folder. Copper precipitates filver from its folution in the nitrick acid. This method is ufed in the mints to feparate the filver from the acid, after the operation of parting. Copper is very much uftd in the arts. All the boilers in dye. houfes which are intended to contain compofitions that do not attack this metal, are made of copper. It is at prefent ufed as a fheathing for the bottom of Ships. All our kitchen utenfils are made of it; and, in Spite of the dan- ger to'which we are daily expofed of being poifoned, and not- withstanding the flow and deftruaive impreffion this metal can- not but produce upon us individually, there are few houfes from which this metal is yet banifhed. It is a defirable objea that a law might be paffed to prohibit its ufe amongft us ; #as has been done in Sweden, at the Solicitation of the Baron de Schof- fer, to whom the pubiick gratitude has ereaed a Statue of the fame metal. It is an allowable infringement of perfonal liberty, when government take upon them to direa the conduct of indi- viduals in fuch a manner as to fecure their own fafety. There is no year paffes in which feveral perfons are not poifoned, by hams, or other food which is fuffered to remain in copper veffels. 3^8 Properties of Mercury. Tinning is not a complete remedy againft this danger j for it leaves an infinity of points where the copper is uncovered.* The fulphate of copper is very much ufed in dying. The cryftals of Venus, and verdigris, are likewife ufed in painting ; they enter into the compofition of colours, varnilhes, Sec. ' The variou3 alloys of copper with other metals, renders it highly valuable in the arts. Brafs, bronze, and bell-metal, are very extenfively ufeful. CHAPTER XII. Concerning Mercury. MERCURY differs from all other metals, by its property of retaining the fluid ftate at the ordinary temperature of the at- mofphere. It poffeffes the metallick opacity and brilliancy; and even ac- quires malleability when deprived of fluidity by a proper degree of cold. The beft afcertained experiment which has been made on this phenomenon, was performed by the Academy of Pe- tersburg, in 1759. The natural cold was increafed by a mix- ture of Snow and highly concentrated nitrick acid ; and the thermometer of De Lifle was caufed to fall to 213 degrees, which correfponds with 46 below o of Reaumur. At this pe- riod the mercury appeared to defeend no lower: the bulb of the thermometer being then broken, the metal was found to be in a congealed ftate, and bore to he flattened by the hammer. Mr. Pallas congealed mercury, in 1772, at Krafnejark, by the natural cold : he then found that; it refembled foft tin. It has been af- certained in England that the degree of its congelation was the* 32d of Reaumur! Mr. Matthew Gutherie, conful at the court of the Emprefs of Ruffia, proved that the degree of cold of this congelation was 32 degrees below o of Reaumur ; and that, when the mercury is purified by antimony, it congeals at 2 de~ grecs lower.—See the Journal Encyclopedique, September, * It may befid?sbe doubted whether the etftrerrjely thin white coating, which conceals the internal furface of tinned cbpptr, be not a kind of bell or Speculum metal, inftead of tin, as it is generally fuppofed to be. T. f For an account of this fubjedt, fee Dr. Bl^gden's Hiftory of the Con- jretation of Mercu:-;', in the fevemy-niird voiuiue of the Philofophica Tr.infaciioiiM. Ores of Mercury. 3*9 Mercury is as indeftruaible by fire as gold and filver ; and its properties in general have caufed it to be arranged among the perfea metals. A cubick Soot of this metal weighs 949 pounds ; and its fpe- cifick gravity is 13.5681.—Briffon. Mercury has been found in the earth in five different ftates. 1. Virgin Mercury is found iri moft of the mines of this metal. Heat alone, or mechanical divifion of the ore, is fufficient to ex- hibit it in the metallick form. Native mercury has been fodnd in digging the foundations of fome houfes at Montpellier ; and this metal has been conftanti ly mixed and confounded with a grey or red clay, which Sorm 3 a bed almoft coritiriubus, at a few feet beneath the foundation of this town. The obfervations which I have had occaSion to make on this fubjea, have afcertained that the mercury exifts in a Stratum of decompofed grit-ftone, very argillaceous, ferru- ginous, and ochreous ; of a red, broWn, or grey colour. Iri this clay, the globules of mercury, in confiderable abundance, Were eafily distinguishable, lying upon gteyiffi plates. Traces are perceived which reSemble dendrites ; and its impreffions are formed by layers of the oxide of mercury. Several pounds of mercury have likewife been fourid in a Well at Vienne in Dauphiny; and Mr. Thouvenel has pointed but to us three mines of this metal iii the fingle province of Dauphiny, according to the indications of Bletori. 2. Mr. Sage read to the Academy, on the nth of May, 1782, the analyfis of an ore of mercury, in the form of a folid oxide* which came frofn Idria in Friuli. It is of a brown red colour 5 and its fraaure is grahulated. It is reducible by mere heat ; and affords oxigenated gas. It emits only half the quantity af- forded by red precipitate j becaufe this oxide contains metallick mercury. It affords ninety-one pounds of mercury per quintal* and a Small quantity of filver. 3. The muriate oS mercury, or corrieous mercury, has been Sound native in the mine oS MuSchel-Lamburg, in the dutchy of Deux-Ponts. Mr. Sage obtained eighty-fix pounds of mercurv per quintal. Mr. Woulfe has likewife discovered, in 1776, a very ponder- ous white, green, or yellow cryftallized ore of mercury; in Which he proved the exiftence oS the Sulphurick and muriatick acids. 4. Mercury is Sometimes naturally amalgamated with other ijietals, Such as gold, filver, arSenick, copper, &c, 2...Y 317° Mines of-Almaden. 5. Mercury is ufually mineralized by fulphur; and the pro- dua is cinnabar or aethiops, according to the colour. Cinnabar is found under different forms. 1. In red cryftals, confifting of two triangular pyramids, truncated, and joined bafe to bafe, or elSe Separated by a very Short intermediate priSm. Cinnabar has likewiSe been found cryftallized in tranfparent .plates. 2. Cinnabar is almoft always found in maffes, more or lefs compaa ; the colour varies from deep black to the brightest red. In this laft ftate it is diftinguiflied by the name of vermillion. Cinnabar has Sor its gangue, quartz, clay, calcareous earth, ponderous Spar, and even coal The ore which the Germans called Brandertz, has for its gangue a bituminous matter, which burns perfeaiy well; and it affords only Six pounds of mercury in the quintal. The principal Cinnabar mines which are wrought in Europe, are thofe of the Palatinate and thofe of Spain. Mr. Sage in- formed us, in 1776, of the procefs ufed in the Palatinate ; and we are indebted to Mr. De Jufficu for a deScription of the meth- od ufed in Spain. In the Palatinate, the pounded and Sifted ore is mixed with one third of lime ; and the mixture introduced into iron cucur- bits, one inch thick, three feet nine inches long, one foot wide, with an opening of five inches. Thefe veflels are difpofed in a gallery. Forty-eight of thefe retorts being arranged in two parallel lines, a fecond row is placed above the firft. To the neck of each cucurbit an earthen pot .is adapted, which is one third filled with water, and accurately luted on. The gallery is heated at the two extremities; feveral apertures formed in the dome ferve the purpofe of chimneys ; and the diftillation is ef- feaed by a fire kept up for ten or twelve hours. This procefs was followed at Almaden till the year 1647, when the following was adopted, as being more fimple and eco- nomical. The furnace is twelve feet high, and four/eet and an half diameter within. At the diftance of five feet and an half from the ground, is an arch upon which the ore is difpofed, and a fire is kindled in the afh-hole. The fublimed mercury efcapes through twelve apertures formed in the upper part of the labor- atory. To thefe apertures, rows of aludels, inferted one in the other, are adjufted, and difpofed parallel upon a terrace, which terminates in a fmall building feparated into as many chambers as there are files of aludels. Each chamber has a cavity in the middle, to receive the fmall quantity oS mercury which may ar- rive to that diftance. Congelation of Mercury. 371 Every furnace contains two hundred quintals of cinnabar, and the fire is kept up for three days. The fulphur which burns is difengaged in the form of fulphureous acid, and efcapes through fmall chimneys made in each chamber. Every repeti- tion of the procefs affords from twenty-five to fixty quintals of mercury. The mine of Almaden has been wrought from time immemo- rial. Its veins are from three to fourteen feet in breadth ; and their breadth is even larger where they join. Hitherto no method has been difcovered to fix mercury but that of extreme cold. This metallick fubftance, naturally fluid, is capable of rifing even by' a very moderate fire ; as is proved by an experiment oSMr. Achard, who having leSt a difh contain- ing twenty pounds of mercury over a furnace which was daily heated, experienced a Salivation £t the end of feveral days ; as did likewife two other perfons who had not quitted the cham- ber. He eftimates this heat at about eighteen degrees of Reau- mur.—Journal de Phyfique, Oaober, 1782. It is dangerous to oppofe the evaporation or dilatation of this metal which is produced by heat. In the year 1732 an alchemift prefented himfelf to Mr. Geoff- roy, pretending he had difcovered the means of fixing mercury. He inclofed the metal in an iron box, and this box in five others, which were placed in a Surnace ; the explofion was So ftrong, that it burft through the boards oS the floor. Mr. Hellot has related a fimilar fact to the Academy. Mercury boils in the Same manner as other liquids when it is heated ; and Sor this purpoSe it does not even require a very con- siderable heat ; the ebullition confifts merely in its tranfition to the vaporous ftate : Sor it may be diftilled like all other fluids, and by that means cleared of its impurities. Boerhaave had the patience to diftil the fame mercury five hundred times Succes- sively : and the metal Suffered no other change, than that it af- Sorded a grey powder, which required only trituration to convert it again into running mercury. Mercury is not eafily changed in the air ; but IS the aaion of the air be affifted by heat, the mercury gradually lofes its fluidi- ty ; and at the end oS Several months forms a red oxide, which alchemifts have diftinguiffied by the name oS Precipitate per fe. The apparatus made ufe oS for this operation is a very large and very flat bottle, cloSed with a Stopper, in which there is a capil- lary perforation. The mercury within the bottle by this means poffeffes the contaa oSair ; and by diSpofing the apparatus upon a Sand bath, and keeping up the State oS ebullition in the fluid, the oxide may be obtained in the courSe of feveral months. 372 Aclion $f Acids on Mercury. This oxide gives out its oxigene by fimple heat, without any ntermedium ; and the mercury refumes its metallick Sorm ; one: ounce affords about a pint. A quintal of mercury takes up a- bout eight pounds oS oxigene. The red oxide oS mercury, ex- poSed to heat, Sublimes in clofe veffels, and may be converted inr to a very beautiSul glaSs. I have obServed this on all occafions when I have made the red oxide by means oS the nitrick acid, according to the proceSs which I Shall immediately defcribe. It is certain that mercury upon which water is boiled, com- municates a vermifuge property to that liquid, though the moft accurate experiments of Lemery have Shewn that the metal does not perceptibly loSe weight; which proves that the principle taken up by the water is very Sugaceous, and So light that it does not conftitute any fcnfible part of the weight. Water which has remained for a certaih time over mercury contraas a very evident metallick tafte. i. The fulphurick acid does not aa upon mercury unlefs affifted hy heat. In this caSe, Sulphureous gas is diSengaged ; and a white powder Sails down, the quantity of which becomes greater in proportion as the acid is decompoSed. This oxide weighs one third more than the mercury made uSe of. It is, cauftick; if hot water be poured on it, it becomes yellow j and. if it be urged by a violent heat, it affords oxigenous gas, and the mercury refumes its natural form. This yellow oxide, obtained by means of the fulphurick acid, is known by the name of Turbith Mineral. It has long been confidered as a fulphate of mercury. Mr. Baume has proved that it does not contain a particle of acid ; and it appears that the water which develops its yellow colour, feizes the fmall quantity of undecom- pofed acid which was mixed with the oxide. If the water which has been poured on it be evaporated, a Salt is obtained in fmall, foft, and dehquefcent needles, which may be deprived of their acid by the fimple affufion of water. This fluid precipi- tates the mercury from them in the form of turbith. 2« The nitrick acid of commerce, at the Strength of thirty- five degrees, diSfolves mercury with violence, even without the affiftance of heat. This folution is accompanied with the dif- engagement of a considerable quantity of nitrous gas ; be- caufe it is neceffary that the acid Should reduce the metal to the ftate of oxide before it can aa upon it. One part of the acid, is consequently employed in difpofing the metal for folution, and the other diffolves it in proportion as it is oxided. This is, what happens when the fulphurick acid is digefted upon a met- al; one portion is decompofed, and reduces the metal into aq e^ide, while the other diffolves it.. Mercurial Salts. 373 The manner of effeaing the folution of mercury in the ni- trick acid, has an influence on the properties of the mercurial nitrate. Bergmann has obferved that the folution which is made flowly and quietly, without difengagement of nitrous gas, affords no precipitate on the addition of water; whereas that which is made by the affiftance of heat, and with lofs of nitrous gas, affords a precipitate. It appears that the nitrick acid, affift- ed by heat, is capable of becoming loaded with an excefs of mercurial oxide, which it lets fall when diluted with water. The method of performing the folution, and the procefs made ufe of to cryftallize it has an equal influence upon the form of the cryftals. i. The folution made in the cold, and left to fpontaneous evaporation, affords cryftals which appeared to Mr. De Lifle to be oaahedral pyramids, truncated near their bafe, and having the four angles refulting Srom the junaion of the baSes of their pyramids likewife truncated. 2. If the fame folution be evaporated, long and acute blades are obtained, lay- ing one upon the other, and ftriated obliquely acrofs. 3. The Solution of mercury effeaed by heat, affords flat and acute nee- dles, ftriated lengthways. The nitrate of mercury is corrofive; it detonates upon coals when it is very dry, and emits a whitifh flame of confiderable brilliancy. The rriercurial nitrate, heated in a crucible, is fufed, and emits a confiderable quantity of nitrous gas together with its water of cryftallization. The remaining oxide becomes yellow; and at length affumes a lively red colour, and forms the fub- ftance called Red Precipitate. In order to make a very fine red precipitate, the mercurial Solution muft be put into a retort, and diftilled until no more vapours come over. An additional quantity oS nitrick acid mufl then be poured on the remainder, and likewiSe diftilled off. ASter three or Sour repeated distilla- tions, a very beautiful precipitate is obtained in fmall cryftals of a very Superb red colour. The Solution of mercurial nitrate forms mercurial water. It is of ufe to afcertain the prefence of fulphurick and muriatick falts in mineral waters. The acids, the alkalis, the earths, and fome of the metals, likewife precipitate mercury from its folution in the nitrick acid. Thefe precipitates always confift of the oxides of mercury in a greater or lefs degree of perfeaion, according to which circum- ftances their colour is fubjea to variation. On this head, Lemery, Baume, &c. may be confulted. Mr Bayen has difcovered that fome of thefe precipitates pof- ,feSs the property of fulminating, when mixed with a fmall 3F4 Fulminating Mercury. quantity of fublimed fulphur. This chemift has pointed out three—i. The precipitate of mercury Srom its Solution in the nitrick acid, by the affiftance of the carbonate of ammoniack. 2. The precipitate oS the Same fluid by lime-water. 3. The precipitate of the folution oS corrofive Sublimate by lime-water. HalS a gros is to be triturated with fix grains oS fublimed Sul- phur. After the detonation, a violet-coloured powder remains which affords a.Sine cinnabar by Sublimation. 3. The muriatick acid does not Senfibly aa upon mercury : but if it be digefted for a long time upon the metal, it oxides it, and at length diffolves the oxide, as may be concluded from the experiments of Homberg, inferted in the volume of the Acade- my of Sciences for the year 1,700. The muriatick acid completely diflblves the mercurial oxides. ' When theSe oxides are nearly in the metallick ftate, or charged with a Small quantity of oxigene, the muriate of mercury is formed. When, on the contrary, the oxide of mercury is fat- urated with oxigene, the oxigenated muriate of mercury, or corrofive Sublimate of mercury, is formed. Corrofive Sublimate may be formed according to two methods; in the dry way, or in the humid v/ay. To make this fait in the dry way, the operator may proceed in various manners. 1. Equal parts of dried nitrate of mercury, decrepitated mu- riate of foda, and fulphate of iron calcined to whitenefs, are mixed together. This mixture being expofed to Sublimation, the produa which ariSes is corrofive Sublimate. 2. Running mercury is uSed in Holland inftead of the ni- trate of mercury ; and the fame refults may be obtained by u- 6ng any oxide of mercury whatever. 3. Equal parts of the fulphure of mercury, and the decrepi- tated muriate of foda, afford the fame fait by Sublimation. This proeeSs oS Kunckel has been revived by Boulduc. 4. Mr. Monnet affures us that he obtained corrofive Subli- mate by treating the dry muriate oS Soda, and a mercurial oxide, in the way of diftillation in a retort. If mercury be diffolved In the oxigenated muriatick acid, the folution, when concentrated, affords very fine corrofive Sublimate. It may likewiSe be obtained by precipitating the mercury Srom mercurial water by the Same acid, and evaporating the Solution. I have obtained very fine Sublimate by prefenting a mercurial ©side, Sufficiently loaded with oxigene, to the ordinary muriatick acid. One pound oS muriatick acid, at the ftrength of twenty- five-degrees, poured upon one pound of red oxide by the nitrick acid,decolours it, in a Short time diffolves it with a violent heatj Mercurius Dulcis. ns and this folution, diluted with water, and properly evaporated, affords from twelve to fourteen ounces of cryftals of corrofive Sublimate. The corrofive muriate of mercury has a ftyptick tafte, Sollow- ed by an exceedingly diSagreeable metallick tafte. When plac- ed on hot coals, it is diffipated in Sumes ; when flowly heateil in Subliming veffels, it riSes in priSmatick cryftals, So much "flat- tened, that their Saces are Scarcely diftinguifhable. The affem- blage of thefe has induced authors to compare them to fword blades lying acrofs each other. This fait is foluble in nineteen parts of water; and when the folution is poncentrated, it affords cryftals Similar to thdfe obtained by Sublimation. Barytes, magnefia, and lime decompoSe this Salt. Half a grds of corrofive fublimate in powder, thrown into a pint of lime- water, forms a yellow precipitate. This fluid is known by the name of Phagedenick Water. Fixed alkali precipitates the mercury in an orange-coloured oxide ; and volatile alkali in the form of a white-powder, which becomes brown in a fhort time. The fame muriatick acid, combined with a lefs perfea oxide of mercury, forms the mild muriate of mercury, or mercurius dulcis. This combination may likewife be made by two meth- ods ; by the dry, or the humid way. i. In the dry way, four parts of corrofive muriate of mercu- ry are triturated in a mortar with three of running mercury. When the mercury has difappeared, the mixture is put into phials, and fublimed three Succeffive times, in order that the combination may be more accurate. This fublimate differs from corrofive fublimate by its infolubility in water, its Infipidity, arid the form of its cryftals, which are tetrahedral pyramids, termi- nated by four-fided pyramids. To obtain this regular form, it is necefliry that the Sublimation ffiould be made at a moderate heat; for, if the heat be Sufficient to liquefy the fait, the refuk is merely cruft, with no appearance oS cryftals. As the tritura- tion of corrofive fublimate is dangerous, on account of the pow- der which rifes, Mr. Baume pours a fmall quantity of water upon the mixture. This liquid accelerates the trituration, and pre- vents therifing of the deftruaive powder. Mr. Bailleau has propofed the incorporating of corrofive fub- limate with water, and triturating it with running mercury. The combination is completed by digefling the mixture on a fand bath by a gentle heat. The matter becomes white, and requires only a finale fublimation. Whenever it is SuSpeaed that mercurius dulcis Still retains a portion of corrouvs Sublimate, 37* Mercurial JEthhps. nothing more is neceffary to be done than to triturate it, and pour boiling water upon it; for by this means the whole of the foluble fait which may have remained, is carried off. Mr. Baume has proved that there fe no intermediate ftate be- tween mercurius dulcis and corrofive fublimate. IS leSs mercury be added to the Sublimate, a proportional quantity of mercurius dulcis only Sublimes, and the reft riSes in the Sorm of corrofive fublimate ; if a greater quantity oS merciiry be added than is ne- ceffary to convert the whole into mercurius dillcis the excefs re- mains in the form of running mercury. The fame chemift has likewife proved, that a portion of the mercury is always loft at each Sublimation ; and that a Small quantity of corrofive fublimate is formed, which ariSes from the alteration of the mercury. Hence it follows that the mercurial panacea, which is made by fubliming mercurius dulcis eight or nine times* is a more fufpicious remedy than the mercurius dulcis itSelf. 2. Mercurius dulcis may likewife be made by decompofing mercurial water by a Solution of the muriate of Soda. The white precipitate which is obtained may be Sublimed, and forms an excellent mercurius dulcis. I communicated this proceSs to the Society of Sciences at Montpellier two years before Mr. Scheele made it known. The corrofive muriate of mercury differs therefore from the mild muriate by the ftate of its acid. The mercurial oxides are equally foluble in the other acids. 3. A folution of borax, mixed with mercurial water, forms a Very abundant yellow precipitate, which is nothing elfe but the combination of the acid of borax and mercury. A fmall quan- tity of this fait remains in folution, which may be obtained Iri brilliant cryftals by evaporation. 4. The acetous acid likewife diffolves the oxide of mercury, and affords white foliated cryftals. Mercury precipitated from a folution of the acetate of mer- cury, combines with the acidulous tartrite of pot-afh, and forms vegeto-mercurial water of Preffavin. The acetate of meicury is the bafis of Keyfer's pills. 5. Mercury, artificially mixed with fulphur, forms the red or black fulphures, known, on account of their colour, by the names Of iEthiops or Cinnabar. To form the iEthiops, or black oxide of mercury, three meth- ods may be followed. 1. Four ounces of mercury may be triturated with twelve Ounces of fublimed fulphur in a glafs mortar. The refult is a black powder, called iEthiops Mineral. Mercurial ASthiops. 377 2. Four ounces of fulphur may be fufed in a crucible, and one ounce of mercury extinguished in it. The mixture readily takes fire, but the inflammation is to be prevented j and the blackifh refidue, being pounded, affords a greenifli powder, which is a true aethiops. 3. The aethiops may be made by pouring the fulphure of pot-affi upon mercurial water. TheSe aethiops afford by Sublimations cinnabar, or the red Sulphurated oxide. But in order to make it with a greater de- gree of accuracy, four ounces of Sublimed Sulphur are SuSed in an unglazed earthen pot, and one pound oS mercury mixed with it by ftirring or agitation. When theSe Subftances have combined to a certain degree, the mixture Spontaneously takes fire, and is Suffered to burn about a minute. The flame is then Smothered, and the refidue pulveriSed, which forms a vio- let powder, uSually weighing about Seventeen ounces five gros. This powder being Sublimed, affords a Sublimate of a livid red colour; which, when pounded, exhibits a fine red colour, known by the name of Vermillion. Three parts of cinnabar, mixed with two ounces of iron fit* ings, afford very pure mercury by* diftillation, which is called mercury revived from cinnabar. Lime, the alkalis, and moft of the metals, may be fubftituted inftead of the iron. Mercury amalgamates with moft other metals. On this , property is founded the art of water-gilding, or gilding upon metals, the tinning of glaffes, the working of gokj. and filver mines, &c. Mercury is likewife ufed in the conftruaion of meteorologi- cal inftruments, in which it poffeffes the advantage over other fluids—r 1. That it does not eafily freeze. 2. It is more eafily and gradually dilatable, according to the fine experiments of Meffrs. Bouquet and Lavoifier. 3. It is very nearly of the fame cjuality in different fpecimens. Mercury may be ufed in fubftance as a remedy againft the volvulus, and it has never been obferved to produce bad effeas. It is mixed with fat, to form unguents very much ufed in venere- al cafes. Thefe arc prepared with one third or half their weight of rhercury, according to the exigence of the cafe. The mercurial water is ufed as an efcharotick. The red oxides anfwer the fame purpofe. The mild mercurial muriate is ufed as a purgative. It en- ters into the compofition of pills which are ufed in venereal caf- es, with the intention of carrying off the morbifick matter by the Skin. 2...Z 37^ Native Silver. The corrofive muriate of mercury is of very extensive ufe, more efpecially againft venereal diforders. This remedy re- quires Skill and prudence ; but I have received it as the com- mon opinion of all phyficians of reputation, that it is the moft powerful and certain remedy poffeffed by the art of medicine. In a large dofe it irritates the fyftem, affects the ftomach, occa- fions fpafms in the lower belly, and leaves impreffions which are difficult to be eradicated. Cinnabar is uSed in fumigations, to deftroy certain infea* which attach themSelves to the Skin. It is likewife ufed asa pigment. CHAPTER XIII. Concerning Silver. t ' SILVER is a metal of a white colour, poffeSfing neither fmell nor tafte, nearly unalterable by fire, very duaile and tenaceous. A cubick Soot of this metal caft weighs feven hundred and twelve pounds ; the fpecificlc*gravity of caft filver is 10.1752. See Briffon.—It is found in the earth in five different States, which we Shall proceed to confider. 1. Virgin or native Silver.—Native filver is found in various forms. 1. In ramifications compofed of oaahedrons inferted one in the other. This variety is known by moft mineralogists under the name of Virgin Silver in Vegetation. Four procef- fes, indicated by Mr. Sage, are known for the cryftallization of filver: amalgamation, reduaion by phofphorus, reduaion by copper, and fufion. A detail of thefe four proceffes may be feen in his Analyfe Chimique, book iii. p. 238, et feq. Native filver is likewife found in fmall capillary, flexible, and intertwined- threads. The decompofition of the red or vitreous Giver gives rife to this fpecies ; it may even be produced by a- flow calcination of one of thefe ores. Silver is likewife Sound in irregular forms ; either in fmall plates difperfed in the gangues, or in maffes. Albinus reports, in the Chronicle of the Mines of MiSnia, that in the year 1478, a lump of native Silver was found at Schneeburg, weighing four hundred quintals. Duke Albert of Saxony defcended into the mine to fee this Surprising maSs of filver, and had dinner Served up upon it. 2. The vitreous filver ore, or Silver mineralized by fulphur. —This ore is of a grey cplour, and may be cut like lead. It cryf- Ores-of Silver. 379 tallizes in oaahedrons, or in truncated cubes, afrid is moft fre- quently found of an indeterminate figure. The fulphur may be extraaed by heat. It affords about Sixteen pounds in the quin- tal. When the fulphur is contained in a greater proportion in this ore, it becomes black, porous, and Sriable. 3. Red filver ore : filver mineralized by Sulphur and arSen- ick.-—This Species cryftallizes in hexahedral pyramids, termina- ting in an obtufe trihedral pyramid, with rhombick faces. It is frequently found in irregular maffes of no determinate figure. It poffeffes the colour and tranfparency of the ruby. Mr. Sage has obtained from this ore, by diftillation, water, carbonick acid, and the fulphurated yellow and red oxides of ar- fenick. If this ore be calcined in a tell, and the mineralizer be Suffered to exhale, the refidue is found to be in the metallick ftate, exhibiting contorted threads of filver at its furSace. Part oS the filver paffes to the ftate oSgrey oxide in this operation. 4. White antimonial filver ore : filver and antimony miner- alized by Sulphur.—This ore is as white as filver ; it is brittle, and of a granulated fraaure. Sometimes it is found in hexa- hedral priSms, truncated and flat at each end : this kind is found in the principality of Furftenburg. When expofed to heat, k becomes as fluid as water, emits antimony and Sulphur, and leaves the Silver behind, together with an oxide oS antimony. This Semi-metal is cleared off by Sufion, affifted by proper fluxes, and cupellation. 5. The corneous ore of filver, or muriate of filver—This fpe- cies is of a dirty yellow grey : it is SoSt, and may be eafily brok- en or cut. A gentle heat cauSes it to flow ; it Sublimes with- out decomposition, is moft Srequently Sound oSno regular Sorm, but Sometimes cryftallized in cubes. The muriatick acid is its mineralizer. Mr. WoulSe has fhewn that it likewiSe contains a fmall quantity of fulphurick acid. 6. Silver is alfo very frequently alloyed with various metals, Such as lead, copper, bifmuth, cobalt ; and thefe ores are Some- times wrought on account of the quantity of filver they contain. The manner oS working a filver ore varies according to its nature ; but all the proceffes uSed in the various countries may be reduced to the following : 1. In Peru and Mexico the mineral is pounded, roafted, waffied, and aSterwards triturated with mercury in copper boil- ers filled with water kept at the boiling heat. The whole is ag- itated by means oS a kind oS mill. The amalgam is aSterwards expreffed in a Skin ; then heated, to drive off the remaining mercury ; after which procefs the filver remains alone. 38© Alloy of Silver. K • This method is defcaive—i. Becaufe the fire volatilizes a portion of the muriate oS filver which abounds in theSe ores. 2. The waShings carry with them a portion of the oxide oS fil- ver. 3. The mercury does not amalgamate either with the muriates of Silver, or the Sulphates of that metal. 2. When Silver ores, mineralized by fulphur or arSenick, are to be wrought, they are roafted, pounded, wafhed, and fufed with lead. This metal feizes all the filver, from which it is again feparated by cupellation. 3. When the filver ore is poor, it is fufed with cupreous py- rites, and the mixture treated in the way of liquation.—See tho article Lead. To determine the degree of purity of the filver, a given weight of filver is fuppofed to be compofed of twelve parts, called pen- ny weights ; each penny weight is divided into twenty-four grains. Silver, clear of all mixture, is faid to be twelve penny weights fine. In order to affay filver, and to aScertain its degree of SineneSs, the regulation of the Court of Monies of France prefcribes, that thirty-fix grains of filver be taken, and wrapped in a plate of lead containing no fine metal, and then expofed to cupellation. From the lofs which the button of Silver that remains on the cupel has fuffered, a judgment is made of the quantity of alloy. If the lofs be one twelfth of the whole, the filver is faid to be eleven penny weights fine. The details relating to this opera- tion may be feen in L'Art £effayer FOr et PArgent, par M. Sage. Silver may be rendered hard by mixing it with copper ; and for this reafon it is alloyed with that metal for filverSmiths worlo, as well as for the coinage. The law permits one twelfth of al- loy in filver money ;* and it is this portion of copper which renders the folution of filver coin in the nitrick acid blue. Silver is not changed by the contaa of air. A confiderable heat is required to fufe it ; but it may be volatilized by ftrong fire without alteration, as is proved by the capital experiments of the Academicians of Paris, made in the focus of the lens of Mr. Trudaine. This metal emits a thick fume, which whitens plates of gold expofed immediately over it. Junker converted filver into glafs, by treating it in a way of reverberation, after the manner of Ifaacus Hollands, in a very ftrong fire. Macquer, by expofing filver twenty times fucceflively to the porcelain furnace of Seves, obtained glafs of an olive green col- pur. It was likewife obferved that this metal, when expofed to * The .Britiih coinage is 11 ounces 3 penny weights fine. T, Habitudes of Silver. 3«' the'focus of a burning mirror, prefented a white pulverulent matter on its furSace, and a greeniffi vitreous covering on the Support upon which it was placed. Though theSe experiments clearly prove that filver is capable of combining with oxigene, the difficulty which is found in ef- feaing this combination, and the facility with which this air is difengaged from the oxides of filver, prove that there is but little affinity between thefe two fubftances. If filver in a ftate of extreme divifion be preSented to the concentrated and boiling Sulphurick acid, Sulphureous gas is dif- engaged : the filver is reduced into a white matter, which is a true oxide of filver ; and contains a fmall quantity of fulphate, which may be obtained in fmall needles, or in plates formed by the union of thefe needles lengthways, as Mr. De Fourcroy has obferved. This Salt flows by heat, and is very fixed. If Silver be precipitated by metals or alkalis, thefe precipitates are reduci- ble without addition. The nitrick acid diffolves filver with rapidity: much nitrous gas is difengaged. The folution is at firft blue: but this colour disappears when the filver is pure ; and degenerates into a green colour, iS it be alloyed with copper. The nitrick acid is capa- ble of diffolving more than half its weight of filver. The Solution then lets Sail cryftals in hexagonal, triangular, or Square plates, which are calledNitrateof Silver,Lunar Cryftals, Lunar Nitre, &c. The folution of thefe cryftals, generally known by the name of Solution of Silver, is very cauftick. It colours the fkin black, burns the epidermis, and fo completely deftroys its organization, that the fpot difappears only by the renewing of the fkin. The nitrate of filver melts on burning coals ; but if it be ex- pofed to a gentle heat, in earthen or metallick veffels, it liquefies, and may then be caft in moulds. This fufed nitrate of filver forms the lapis infernalis. Care muft be taken to pour it out as foon as it is fufed ; becaufe otherwife the acid would be dif- engaged, the filver would be revived, and the lapis infernalis, or lunar cauftick, would lofe its virtue. Lapis infernalis, made with pure filver, and prepared as above defcribed, is whitifh ; whereas it is blackiffi whenfuffered to re- main in fufion for any time. ' Lapis infernalis is very frequently mixed with nitrate of cop- per. This fraud is reprehenfible, becaufe it is an alloy which renders wounds of a bad charaaer. - The lapis infernalis is ufed as an efcharotick, and to corrode fungous excrefcences. ' - Silver may be precipitated from its folution by lime-water, alkalis, and feveral metals. Thefe laft exhibit very important phenomena. 3'* Habitudes of Silver* <■.. I. A plate pf copper, iramerfed in a'folution of filver diluted in" water, precipitates the metal. It adheres at the moment of precipitation to the furface of the copper, where it forms a kind of mofs. In proportion as the filver is precipitated, the water affumes a blue tinge ; which proves that the copper is diffolved in the nitrick acid, in the room of the filver. When the whole of the filver is difengaged, the water is to be decanted, the Sil- ver dried, and fufed in crucibles, to, be caft into ingots. This filver almoft always retains a fmall quantity of copper; of which it may be deprived by cupellation with lead, which ren- ders the filver pure; this proceSs is uSed in the mints* where the parting operation of gold from filver is performed. • The firft ftep confifts in feparating the filver by means of nitrick acid j and this is afterwards precipitated by the addition of copper.^ 2. The filver is likewife precipitated by mercury. In this operation it amalgamates with a fmall quantity of the mercury, and forms tetrahedral cryftals terminated by a tetrahedral pyra- mid, which cryftals are articulated into each other. This ar- rangement gives them the form of a vegetation ; and has caufed the precipitate to be known by the name of the tree of Diana, Arbor Diana. Lemery, Homberg, and other chemifts, have fucceflively published proceffes to produce this phenomenon ; but that which has fucceeded beft in my hands, is defcribed by Mr. Baume* Six gros of the folution of filver, and four of that of mercury, both well Saturated, are taken, and diluted with five ounces oS diftilled water. TheSe are to be put into a conical veflel; and an amalgam of feven parts of mercury, and one of filver, is to be poured in. A multitude of fmall cryftals inftant- ly appear to difengage themfelves Srom the furface of the amal- gam, upon which new ones articulate themfelves; and a veget- ation is produced, which perceptibly rifes under the eye of the fpeaator. To render this phenomenon more Striking, I decant the exhaufted water, and Substitute SreSli; by this means I can fill any veffel whatever with thefe vegetations. The mercury amalgamated with the filver, in this operation, may be Separated by means oS fire. The muriatick acid does not diffolve filver, but it Speedily diflblves its oxides. The oxigenated muriatick acid diffolves filver. To produce a certain and fpeedy combination of the muri- atick acid with filver, this acid is to be poured into a Solution of the nitrate oS filver. A precipitate immediately Sails down, which is known by the name of Luna Cornea. This muriate of Silver is very fufible ; and runs into a grey and tranfparent fubftance, considerably refembling horn. If a Stronger degree Fulminating Silver, 3«3 of heat be applied, it is decompofed, part is volatilized, and the other part reduced into filver. The muriate of filver, expoSed to the light of the fun, be- comes brown in a Short time. Oxigenous gas is diSengaged ; which may be colfeaed by placing it under water, according to the proceSs of Mr. Berthollet. Moft of the folutions of the metals have the fame property. Lunar nitre likewife becomes coloured, and emits its oxigene and nitrous gas. One pound of boiling water does not diffolve more than three or four grains of muriate of filver, according to the observation of Mr. Monnet* The alkalis are capable of decompofing the muriate of filver, and Separating the metal. The filver may be difengaged from its muriate by fufion with three parts of black flux. Mr. Berthollet has taught us the following procefs, to form the molt dreadful and the moft aftoniShing fulminating' powder we have yet been acquainted with. Take, fine Silver of cupella- tion ; diffolve it in nitrick acid; precipitate this folution by lime- water ; decant the water, and expofe the oxide for three days to the air. Mr. Berthollet is of opinion that the prefence of light has fome influence in the fuccefe of tins?experiment. Mix this dried oxide in ammoniack, or volatile alkali, and it will affume the form of a black powder j decant the fluid, and leave the powder to dry in the open aifc, This as the fulminat- ing filver. ^ Gunpowder, and even fulminating gold itfelf j cannot be com- pared with this new produa. The contaa of fire is neceffary to cauSe gunpowder to detonate ; and a determinate degree of heat is required to cauSe fulminating gold to fulminate : but the contaa of a cold body is fufficient to produce the detonationof fulminating Silver. -In a word, this produa,once obtained, can no longer be touched : no attempts muft be made to indofbjt in a bottle, but it muft be left in the capSule wherein the evap- oration was performed. It is ufelefs to obferve, that the fulmination ought not to be attempted but with fmall quantities ; the weight of a grain, for example : for a larger maSs would give riSe to a dangerous deto- nation. The neceSfity of making this preparation with the face covered with a mafk with glaSs-eyes, may be eafily conceived. It is prudent to dry the fulminating filver in fmall metallick cap- fules. The following experiment will complete the notion which ought to be formed of the fulminating property of this prepara- tion. 384 Properties of Gold. Take the ammoniack which was ufed in the conversion of the oxide of filver into the black precipitate which forms fulminat- ing filver : put this ammoniack into a Small mattraSs of thin glafs, and let It be Subjeaed to the degree of ebullition neceffary to complete the combination. Take the mattrafs from the fire ; and a rough covering of cryftals will be formed on its internal furface which is beneath the fluid. If one of thefe cryftals be- neath the cold fluid be touched, an explofion takes place which breaks the mattrafs. The procefs for obtaining fulminating Silver being defcribed, its effeas known, and the cautions neceffary for repeating the experiment being well afcertained, we fhall fpeak a word con- cerning the theory of the phenomenon : it is the fame as that of fulminating gold, laid down by Mr. Berthollet.—See the Me- moirs of the Royal Academy of Sciences, for the year 1785. In this operation, the oxigene, which adheres very flightly to the filver, combines with the hydrogene of the ammoniack. From the combination of the oxigene and the hydrogene, water in the ftate of vapour is produced. This water, inftantly vaporized,' and poffeffing all the elasticity and expanfive Sorce of that State, is the principal cauSe'of the phenomenon ; in which the nitro- gene, which is diSengaged from the ammoniack, with its whole expansibility, likewiSe bears a principal part. After the fulmination, the filver is found reduced or revivi- fied ; that is to fay, it has reSumed its metallick ftate. It again becomes the fame white, brilliant, and pure metal which it was when taken out of the cupel. The principal ufe of Silver is in coinage, as the representative fign of the value of other commodities. Its metallick brilliancy has cauSed it to be adopted as an orna- ment ; its hardneSs and unchangeableneSs in the air, render it ve/y valuable. It is alloyed with copper, to Sorm folder ; whence it happens that filver utenfils are fubjea to ruft and verdigris, at the places where they are Soldered. CHAPTER XIV. Concerning Gold. GOLD is the moft perfea, the moft duaile, the moft tena- cious, and the moft unchangeable, of all the known metals. A cubick foot of pure gold, caft and not hammered, weighs 1348 pounds ; and its Specifick gravity is 19.2581.—See Briffon. Ores of Gold. 38.« Gold has neither Smell nor tafte ; its colour is yellow, and this varies according to the purity oS the metal. 1. As Gold is Subjea to very little alteration, it is almoft al- ways Sound in the native ftate; and under this Sorm it exhibits the Sollowing varieties :—1. It is Sound in octahedrons in the Gold mines of Boitza in Tranfylvania. Thefe oaahedrons are fometimes truncated in fuch a manner as to have the appearance of hexagonal plates. This native gold is alloyed with a fmall quantity of filver; which, according to Mr. Sage, gives it a pale yellow colour. It has likewiSe been Sound crySlallized in tetrahedral priSms, terminated by Scur-fided pyramids. The amalgam made with certain precautions is likewiSe capable of Caufing gold to affume a form nearly fimilar, according to Mr. Sage ; and gold reduced by phofphorus fometimes exhibits oaahedral cryftals. Gold likewife cryftallizes by fufion. Meffrs. Tillet and Mon- gez obtained it in fhort quadrangular pyramids. 2. Native gold fometimes exhibits fibres or filaments of vari- ous lengths •, it is likewife found in plates diffeminated on a gangue. The gold ore of Lagardet, a few leagues diftant frorh Alemont in Dauphiny, is of this kind. 3. Gold is likewife found Sometimes in Small plates or Spangles, difperfed in Sand or earths : under this Sorm it is Sound in the auriferous rivers, fuch as the Ariege,.the CeZe, the Gardon, the Rhone. Thefe fmall plates are Sometimes one line in diameter, but moft commonly too fmall to be feen by the naked eye. 4. Gold is fometimes found in irregular maffes ; in which inftance it is known by the name of Gold Duft. Very large pieces of this kind are found in Mexico and Peru. 3. Gold is fometimes mineralized by fulphur, by the means of fire. The auriferous pyrites are frequently found in Peru,. Siberia, Sweden, Hungary, &c. To afcertain whether a pyrites Contains gold or not, it muft be pounded, and nitrick acid pour- ed upon it until it takes nothing more up. This folution mult then be diluted with much water. The lio-hteft infoluble parts may be carried off by wafhings ; and the refidue, upon exami- nation, will fhew whether it contains gold or not. When the martial pyrites is decompofed, the gold is always difengaged ; and it is probable that the fmall plates of gold in the auriferous rivers, are afforded by a decompofition of this kind. Gold is fometimes mineralized by fulphur, with the affiftance of zinc, as in the gold mine of Nagyag. This ore likewife con- tains lead, antimony, copper, filver and gold. 4. Mr. Sage has given a defcription and analyfis of an arfer.-8 ical ore of gold. S... A 386 Method of Working Geld Ores. 5. Gold likewife exifts naturally in vegetables. Becher ob- tained it. Henckel affirmed that they contained it; and Mr. Sage has refumed this enquiry, and found it according to the following table, which exprefles the quantities of gold obtained from the quintal of the feveral earths. Ounces, Gros. Grains. Rotted manure (.terreau) o 1 S 6 Earth of uncultivated ground > 3 i6 (terre de Bruyere) > Garden mould o S o Mould of a kitchen gp.rden "p manured with dung yearly > % 3 40 for fifrty years j Thefe refults were at firft contefted ; bat at prefent it ap- pears to be generally agreed that gold is obtained, but in a lela quantity. Mr. Berthollet obtained forty grains and eight twen- ty-fifths of gold in the quintal of afhes. Meffrs. Rouelle, Dar- cet, and Deyeux likewife obtained it. It is therefore a phyfical faa, that gold exifts in vegetables. The method of working the ores of gold is nearly the fame at that ufed with filver ores. When the gold is in a native ftate, nothing more is required than to divide the ore by the pound- ing mill, and afterwards to waSh and amalgamate it. If the ore be mineralized, it is torrefied, pounded, wafhed, SuSed with lead, and afterwards cupelled, "lliquation is likewife ufed for poor ores. Thofe perfons who explore the gold in fmall plates diffemi- nated in the fand of certain rivers,' are known in France by the name of Orpailleurs, or Pailloteurs. The paiiloteurs of the river TJze, after having afcertained that the earth is fufficiently rich to be wrought, place a table feveral feet in length, and a- bout a foot and a half in width, on the banks of the river with ledges round three of its fides. Pieces of fluff with along nap are nailed on to this board ; and the fand is thrown upon it, and wafhed to carry a«vay the lighter particles. When the (luff is fuf- ficiently charged with the fmall particles of gold, it is Shaken in- to a veffel, agitated with water to carry off the lighteft fand, and afterwards amalgamated with mercury.* Mr. Ell has given us an ample account of the procefs ufed in working the gold ores * For a very full account oS the treatment of auriferous Sands, the fol- lowing works may be confulted :—1. The Memoir of Mr. Reaumur on the Auriferous Sands of France, printed among thofe of the Academy for the year r7i8. 2. The Memoir of Mr. Guettard on the Ariege, inlerted in thevolume 101-1761. 3. The Memoir upon the Gold which is obtained from the Ariege in the county of Foix, by the Baron de Dietrich. In this laft work, the various proceffes are difcuffed ; and this celebrated miner- alogist propofes others more economical and advantageous. Method of Working Gold Ores. 387 in Spanish South-America. A fufficient quantity of water" is procured to wafh them. A Stream is made to carry off the earth, and every lighter fubftance. Negro Slaves, difperfed on the banks, throw in frefh earth ; while others, Standing in the brook, work it about with their Seet and hands. Care is taken to lay pieces of wood acrofs the current of the water, to retain the lighter particles of the metal. This work is continued for a month, and even for years together. When it is propofed to terminate it, the water is turned off; and then, in prefence of the mafter, the workmen take up the fand with wooden veffels, in the form of (hallow funnels, of one foot in diameter, at the bottom of which is an aperture of one inch in width. ThisdiSh is filled with fand ; and by a circular motion the lighter fubftan- ces are caufed to flow off, while the heavier fettle to the bot- tom. The platina is afterwards feparated grain by gram, with the blade of a knife, upon a Smooth board. *The reft is amalgamated, firft by working with the hands, and afterwards with a wooden peftle in mortars of guaiacum wood : after which the mercury is feparated from the gold by fire. The Baron de Born has reduced the method of working all the ores of filver and gold to one fingle procefs. The account which he has given of this procefs in his work, may be reduced to the following operations: 1. The mineral is pounded, divided, and Sifted. 2. It is properly roafted. 3. It is mixed with muriate of Soda, water, and mercury-; and agitation is uSed to facilitate the amalgamation. 4. The mercury is expreffed from the amalgam. 5. fhe expreffed mercury is expofed to diftillation. 6. The filver is refined by the cupel. TheSe operations were firft executed at Schemnitz in Hunga- ry, and afterwards at Joackimftal in Bohemia, in the prefence of the greateft mineralogists in Europe, fent hither by the vari- ous Sovereigns of Europe. The muriate of foda is ufed to decompofe the fulphates pro- duced by the calcinations. To determine the finencfs of gold with accuracy, the pureft is SuppoSed to be twenty-four carats, and thefe carats are divid- ed into thirty-Second parts; the carat is always reprefented by a grain poids dc marc. The law direas the operations to be performed upon twenty- four grains of gold, tolerates twelve, and prohibits fix, on ac-. count of the difficulty of appreciating the divisions which refult from thefe fmall quantities. 388 FffieB of Heat on GM. In the parting affay, very pure Silver muft be made ufe of, This is mixed with the gold in the proportion of Sour to one, which has occafioned the name of Quartation to be given to the procefs. Mr. Sage has Sound that two parts and a halS of filver to one of gold form the mixture moft proper for making the cornet of affay. The two metals are wrapped up in a thin piece of lead four times the weight of the gold, and this mixture is put into the cupel when it is very hot. The refult of the cupel- lation is a button containing fine gold and fine filver. This is flattened, lamellated, and rolled up into a fpiral; put into a fmall mattrafs, and fix gros or drams of" pure nitrick acid, at thirty- two degrees of concentration, are poured on it. As foon as the mattrafs is heated, the metal becomes brown, the filver is diffolv^ ed, and much red vapours are diSengaged. At the end oS fifteen minutes the Solution is decanted ; and an ounce of very pure acid, rather more concentrated, is poured on, to carry away the laft portions oS filver. This Solution is decanted, after a digef- tion of fifteen or twenty minutes ; at which period warm water is added, and the cornet is waffied until the water comes off taftelefs. It is then dried in a crucible, weighed, and the fiue- nefs judged by the diminution of its weight. Schindlers and Schutlerhave maintained that gold always re- tains a fmall quantity of Silver, which they have called the Inter-* halt, or Surplus. Mr. Sage Sound a Sixty-fourth part of a grain in the beft conduaed affay. In order to feparate tht filver which is diffolved in the nitrick acid, this folution is diluted with a confiderable quantity of wa- ter, and flat pieces of copper are plunged in it ; which, precip- itate the filver, as we have obferved in treating of the Solution of filver. Gold, expoSed to fire, becomes red-hot before it melts. When melted it fullers no alteration.* Kunckel and Boyle kept it in aglafs-houSe Surnace for feveral months without change. Homberg has neverthelefs obferved that this metal, expofed to the focus of the lens of Tfchirnaus, fmoked, was volatiiized, and even vitrified in part. Mr. Macquer has verified thisobfervation by the mirror of Mr. De Trudaine ; he obferved the gold fume become volatilized, and covered with a dull pellicle, which con- ftituted a violet-coloured oxide towards the middle. Gold is not attached by the fulphurick acid. The nitrick acid appears to have a real aaion unon it. Brandt IS the firft who announced the folution oS gold by this acid. * Gold when fafed by a ftrong heat is of a beautiful green colour during khe felipn. • Nitrous Solution of Gold. 3«9 The experiments were made in the prefence of the King of Sweden, and verified by his Academy. Meffrs. Scheffer and Bcrgmann have confirmed the affertion of Brandt; and Mr. Sage afterwards publifhed a feries of experiments, on this fub- ject. I am convinced, from my own experiments, feveral times repeated, that the pureft nitrick acid attacked gold in the cold, and diflblved a fixty-fourth part of a grain. When very pure nitrick acid is boiled upon gold equally pure, the folution may be afcertained in three ways—1. By the diminution of the weight of the metal. 2. By evaporation of the acid ; in which cafe a purple fpot remains at the bottom of the evaporatory vef- fel. 3. By the parting operation, by means of a plate of filver put into the liquor. In this cafe black flocks are in a ffiort time difengaged, which confift of the gold itfelf. Thefe phe- nomena appear to announce a true folution ; and not a fimple divifion or SuSpenfion, as was SuppoSed. The quantity of gold diffolved appeared to me to vary accord- ing to the ftrength of the acid, the time of the ebullition, and the thicknefs "" M. L. affirms that platina is malleable in its natural ftate 5 and he paffed it through the flatting mill in the "prefence of Meffro. Tillet and Darcet. "3 ' t Platina undergoes no alteration by expoSure to the air ; and* fire alone does riot even appear to poffeSs the power of changing it. Meffrs. Macquer and Baume kept it feveral days in a glafs- houfe furnace, without its grairis having Suffered any other change than that they were Slightly agglutinated. It has never- theless been ascertained that heat, kept Up for a long time, tat- riifhes its furface, an J increafes its Weight?'' Margraff formerly. made this obfervation. ' Platina expofed to the focus of the burning mirror of Mr. De Trudaine, fumes and melts. This metal may be hammer- ed like gold and filver. It may likewife be fufed upon char- coal, by the affiftance of oxigenous gas. This fubftance refills the aaion oS the acids, fuch as the Sulphurick, the nitrick, and the muriatick acids -„ it is foluble only in the oxigenated Characters of Platina, 305 muriatrck and ,£he, nitro-muriatick acids. One.. pound of fhe latter, digefted on.anf ounce of platina^ firft affumes a yek Jow. cblour,, «ien an^ orange .colour, ancj laftly a very obfcure $rown. This Solution tinges animal Subftances brown; it jponlaneoufly depofites .: fmall irregular Sawn coloured cryftals; but. |f ft, b^ concentrated* larger cryftals are obtained, fometimes of ahAoc*tahedral form, as, Bergmann has obferved. The muri- ate of platina is Scarcely cauftick, though Sharp; it fufes in the fire, jives out its acid, and leaves, an ob/cure grey oxide. . Thefulghurick.acid, poured on. this folution, forms a rirecip- itafe of a dark cplour;; the precipitate occasioned by the muri- atick acid, is yeilowifh. The alkalis precipitate platina frOm its folution ; but if it be gradually precipitated by pot-afh, the precipitate 13 diflblved by the alkali in proportion as it is formed. A folution of the muriate of ammoniack, poured info a folu- tion of platina, forms'an orange-coloured precipitate, which is a true faline fubftance, totally Soluble in water. This grecifri> tate ha6 been fufed by Mr.,De Lifle in a common fire (of a fur-: nacej. The reSult of the fufion is platina, Still altered by Some pprtion of faline matter; for it does, not acquire ductility but by,expofure to a much Stronger heat.. t The property which the muriate of ammoniack pofleffes of precipitating platina, affords a very fimple .method of ascertain- ing the mixture of this metal with gold: fo that the Sear of this alloy, which had alarmed (he Spanish ministry fo much as to occafiori them to forbid its being wrought, does not at prefent exift, as we poffefs a fimple method of ascertaining the fraud : and it is much to be wiffied that this very precious metal fhould be reftored to the arts, to which it cannot but be very ufeful, by its brilliancy, its. hardnefs, arid its unchangeable nature. ; The procefs of Mr. De Lifle to fufe .platina, was published 1774. Mr. Achard published a fimpler,method* pearly at the fame time : it confifts.in taking two grofc fit, platina, two gros of the wbate oxide of arfenick, two gros of .the acidulous tartrite of pot-afh, and putting them into a crucible well lilted. This is to be expoSed for an hour.to a violent fire, which fufes the platina ; but it is brittle, and whiter than ordinary platina. It is then to be expoSed to a confiderable heat under a mufffe; by which means all the arfenick which, was combined with the pla- tina is diffipated, and this metal leSt in. a State of purity. Vef- fels of platina may be formed, by filling clay moulds with the alloy of platina and arfenick ; and expofing' the mould in the muffle, to diffipate the femi-metal.. 390 Methods of Fufing Platina. t Mr. De Morveau fubftituted the arfeniate of pot-afh to ad- vantage, inftead of arfenick ; and he had already fufed platina with his vitreous flux, made of pounded glafs, borax, and char- coal. r Mr. Pelletier fufed platina, by mixing it with phofphorick f£*afs and charcoal. The phofphorus then unites with the plati- na *, and the phofphure of platina is expofed to a degree of heat fufficient to volatilize the phofphorus. Mr. Baume advifes to fufe platina with a flight addition of lead, bifmuth, antimony, or arSenick ; and to keep the alloy in the .fire a long time, to diffipate the metals which have facilitat- ed the? fufion. J' PSajina may likewife be fufed with a metal foluble in an acid: the mixture being pulverized, the alloyed met al may be diflblv- ed ; and the powder of platina may then be fufed with the flux ojf.De Morveau. - ^Inftead of ufing a foluble metal, a calcinable metal may be employed, and treated as before. * ^The cubick foot of crude platina weighs 1092 livres 1 ounce 7, gros 17 grains ; platina purified and fuSed weighs 1365 li- vres *, and purified platina forged weighs 1423.8.7.64. Moft of the neutral Salts have no perceptible aaion upon pla- tina. The reSults of feveral curious experiments may be feen in the Memoirs of Margraff. .. The nitrate of pot-afh alters platjna, according to the experi- ments of Lewis and Margraff. Dr. Lewis by heating a mix- ture of one part of platina and two parts of this nitrate, during three times twenty-four hours, obferved that the metal affumed a rufty colour. By diffusing the mixture in water, the alkali was diffolved j and. the platina, deprived of all the foluble mat- ter, is diminished one third. The powder taken up by the alka- li is the oxide of iron, mixed with the oxide of platina. TheSe. experiments, as likewiSe the property which platina poffefles of being aaed on by the magnet, prove that it contains iron ; and Mr. de Buffon has concluded that this metal is a nat- ural alloy of gold and iron. But it has been objeaed that the* artificial alloy of thefe two metals, made in every poffible pro-. portion, never refembles platina ; that this metal departs more from the properties of gold in proportion as it is deprived of iron 3 fo that it is confidered as a truly peculiar metal. This metal is capable of being alloyed with moft of the known metals. Scheffer firft affirmed that arfenick rendered it fufible. ' Meffrs. Achard and De Morveau have availed themfelves of this property to fufe it, and compofe veiTels. • Alloys of Platina. • 39? Platina eafily unites with bifmuth. The refult is eager, very brittle, difficultly cupelled ; and the refult is a maSs which hat little duaility. Antimony likewiSe facilitates the fufion of platina. The al- loy is brittle ; part of the antimony may be difengaged by fire ; but a fufficient quantity remains in combination to deprive the platina of its weight and duaility. Zinc renders this metal more fufible. The alloy is very hard; great part of the zinc may be volatilized by fire ; but the pla- fina always retains a fmall quantity. This metal unites eafily with tin. This alloy is very fufible, and flows clear; it is eager, and very brittle : but when the tin is in a large proportion, the alloy is duaile ; its grain is coarfe, and it becomes yellow by expofure to the air. Lead unites very well with platina. A Stronger heat is requir- ed to fufe this than the foregoing alloy. It is not duaile j is no longer capable of being abforbed by the cupel, the abforption only taking place when the lead is in excefs ; but the platina re- mains always united to a confiderable portion of the metal. Neverthelefs Meffrs. Macquer and Baume cupelled one ounce ■» of platina and twenty ounces of lead, by expofing this alloy, for fifty hours, in the hotted part of the porcelain furnace at Seves. Mr. De Morveau had the fame refult in Mr. Macquer*s wind- furnace : the operation lafted between eleven and twelve hours; Mr. Baume obferved that the platina obtained by this procefs pofleffes the power of being forged and foldered completely, without the affiftance of any other metal, which renders it a moft valuable acquisition in the arts. *Dr. Lewis could not unite forged iron with platina; but hav- ing melted crude iron with this metal, there refulted an alloy fo hard that the file could not touch it; it was duaile in the cold/ but broke Short when hot. Copper and platina alloyed together form a very hard metal, which is duaile, while the copper predominates in the propor- tion of three or four to one ; it takes a fine polifh, and was not tarnifhed during the fpace of ten years. Platina, alloyed with filver, deprives it of its duaility, increaf- es its hardnefs, and tarnifhes its colour. Thefe two metals may be feparated by fufion and repofe. Lewis obferved that the Sil- ver which is fufed with platina is thrown up againft the fides of the crucible with a kind of explofion : this phenomenon appears to be owing to the Silver, as Mr. Darcet found it break porcelain balls in which it was inclofed, and out of which it was projeaed by the aaion of the fire. ,> %$$ Concerning Tungsten, Gobi is ncjt.«£ Tungften, or the Heavy. Stone of the .Swed^Si;. the,other known by the name of Wolfram by mine**- aiogifts. "VVeShall examine-eacb feoasaielyi. ; AS.T1C1X i Concetoing. Tungften. TuiR*ig*o isii^iuManceofan opaque' white cofewj Very heavy| atod c^a^mbd^ateSdtgTeeorhardntSs: its dryftals'are'octahe- drons. . Its fpecifick gravity is dlotfctei according to BYiSfon';' fronr 4.09^ tcV 55 8; according to Kirwan. The* cUbick'fbot weigh^42,4^rvres.'-io-ounces 3•grosser'grainsi Wheirexpofed' withoutadditronto:theiffime•Qf^theoioV-plp"eJ, it-decrepitatis without -nfeklng. "With4ot!a1r is divided with'a Ih^hterret^eTctmceiris/partr^'foluble in thenatfve phofphate, or n^rocofmickHialt.V arrtpafrbrds a fine blue- colour Without the leaft'appearance of'red in therefraaed light," as happens with cobalt. It is foluble in borax without efferveffcertctr. ExtraBion of the Acid of Tungsten, |$£ Bergmann affirm* that by pouring the muriatick acwf vtpptH pulverized tungften the powder immediately aflumes a fke bright yellow colour. To this* charadter fcTcheele adds tlWttf of becoming bluiffi when boiled in the fulphurick acid. - This fubftance has a Sparry appearance, arid' was fbrijf con- founded with the white tin ore. Ft is found at Bitfberg, at Ridd- harhittan, at Marienburgv at' Altemburg in Saxony; and at Sau- kerg near BhreuSriederfifof SfT , Mr. RaSpe, in Grell's Annals for June r 7$$-, gave an account7 of two mine* of- tungften in the province of Cornwall, fTdrit Which thoufands of tons might be extraaed. This phtlofopher obtained the metal in- the proportion of about thirty-fix llvfe? the quintal. He adds that this metal contains* little iron ;that it is very fixed, and refractory in the fire ; and that ira&s on glafs. like the hardeft fteel. r Cronftedt arranges- the tungften- among1' the* now ores ; arn$f defines it to be ferrvma*li&f3*nt terra vuadttm incogjiitifrinthtfr ntixtum. • &£ Scheele has affirmed that it is a fait refUltrrtg from the com- bination, of calcareous earth with a peculiar acid j which acidr combined with lime-water, regenerates tungften: Bergmann confiders the acid earth of tungften as a metalEcJr acid. •.-.-...> Several proceSTes are at prefent known for extraftimjtho a,cidi of tungften. 1. Any defired quantity of this mineral is to be pulverised, and fufed with four times its weight of carbonate of pot-aft^. and poured out upon a plate of. metaL The mafs is then to he' diffolved in twelve parts oft boiling water* A white powdarSetMr arates during the Soluiifift and falls to the bottom of the veffefc This precipitate is a true carbonate oftfime, mixed with a fmatf' quantity of quartz, and a portion of undecorapofed tungften. The carbonate of lime: may be taken up from the pfeeipkare-bjt' nitrick acid ; and the remaining tungften being mixed with the former proportion of carbonate of pot-aSh, is to be fufed't diffolv- ed, and by a repetition of theSe operations will at length be to- tally decotripoSed. The water in which the fufed maffes were wafhed, holds in folution a fait formed by the tungitick acid and, the alkali made ufe of. If this folution be faturated with ni- trick acid, it feizes the alkali; the folution becomes thick ; and a white powder Sails down, which is the tungftick acid. 2. Scheele tfie author of* this firft proceSs, propofes a Second, which confifts in digefting three parts oS weak nitrick acid upon one of pu^verifed tungften. This powder becomes yellow; the fluid is then decanted, and two parts of aramonuck are poured 4°° Acid of Tungsten* upon the yellow ponder. The powder then becomes white ; and in this way the repeated aaions of the acid and the alkali are applied until the tungften is diffolved. Out of four fcruples, treated by Scheele in this manner, there were three grains of infoluble matter, which was a true quartz. By adding the pruf- liate of pot-affi to the nitrick acid made ufe of, he obtained two grains of Pruffian blue; pot-afh precipitated three of chalk; and the ammoniack uniting to the nitrick acid, precipitated an acid powder, which is the true tungftick acid. In this experiment the nitrick acid feizes the lime, and uncov- ers the tungftick acid, which is Seized by the alkali. The muriatick acid may be Substituted to advantage inftea4 of the nitrick acid, and even gives it a yellower colour. Scheele and Bergmann considered this acid powder as the true tungftick acid in a ftate of purity. Meffrs. Delhuyars have af- ferted that this acid was mixed with the acid made ufe of in obtaining^, and alfo with the alkali; they affert that the yellow powderjhhich is uncovered by the digeftion of the nitrick acid, 15 the true acid oxide of tungften without mixture. The white powder which is obtained by decomposing the al- kaline folution of tungften by an acid, is acid to the tafte, red- dens the tinaure of turnSole, precipitates the Sulphure of alkali of a green colour, and is foluble in twenty parts of boiling water. Properties of the white powder cb- Properties of the yellow matter ob- tained by decompofing the folution tainedby fire or by acids. of the ore of tungften by an acid. x. An acicf tafte, reddening the i. Infipid, reddening the tincture ihcture of'turnfole. of turnfole. %. Expofed to flame urged by a. Treated with the Wow-pipe, the blow-pipe, it paffes to a brown it preferves its yellow colour in the aqd black colour, without afford- the exterrfalflame ; but Swells up and ing either fumes or Signs of fuSipn. and becomes black, without filling, in interiour blue flame. 3. It Is foluble in twenty parts 3. It is infoluble, but capable of be- •f boiling water. coming fp divided as to paSs through the filters. 4. It becomes„yeHow by boiling 4. The three mineral acids have no ijithe nitrick and muriatick acids, action upon it. and bluifh in the fulphurick acid. From this comparison it appears that the acid is purer in the yellow powder than in the white ; and the faline combinations of thefe two fubftances have confirmed Meffrs. Delhuyars iri their opinion. The yellow acid, combined with pot-afh, either in the dry or humid way, forms a fait with excefs of alkali. If a few drops cf nitrick-acid^.be poured oh this fait, a white precipitate is inr ftantly" formed, which Isrediffolvedby agitation. y/hcn all the Properties of Wolfrdm, ajb\ alkali is faturated, the folution is bitter; if more acid be poured iri, the precipitate which falls down is no longer foluble. This precipitate, when well edulcorated, is exaaiy of the fame na- ttire as the white powder we have fpoken of. The experiments of Meffrs. Delhuyars, and of Mr. De Morveau, prove very clear- ly that this white powder contains the acid of tungften, a por- tion of the pot-afh with which it was before combined, and a fmall quantity of the precipitating acid. It is therefore well proved that the yellow matter is the pure oxide, and the true tungftick acid. It is likewife very certain that this acid exifts ready formed in the metal ; and that its ox- igene is afforded neither by the decompofition of another acid^ nor the fixation of the oxigenous gas of the atmofphere; it ap- pears to exift in the rtiineralj and to cdhftitute a kind of fait of many principles. ••;l . The pure tungftick acid' diffolves ammoniack ;■' but the reSuIt is always wlth.exceis of alkali. This folution affords by evapo- ration fmall cryftals, of a penetrating bitter tafte, foluble in wa- ter, arid then reddening blue paper.' The alkali is eafily fetJa-' rated -, and thefe cryftals return b£ calcination to the flate of yellow powder, entirely fimilar to that which entered into its compofition. If tfie1 calcination be made in clofed veffels, the refidue is of a deep blue colour} for the yellow colour does not appear-.unlefo the calcination be made in the open air. ,^ The experiments of Mr. De Morveau permitted him to clafs the affinities of this acid in the following order, which is the fame as that of the arfenical acid : lime, barytes, magnefia, pot* affi, foda, ammoniack, alumine, metallick fubftances. ARTICLE tt i.' Concerning Wolfram. ' Wolfram is of a blackifh brown colour, fometimes affecting the Sorm of an hexahedral compreffed priSm, terminated in a dihedral Summit. Thefe furfaces are frequently ftriated longi- tudinally,.'Its fraaure is lamellated, foliated, and the leaves are flat, though rather confided. Externally it refembles fchorl; but'is not fufible, and is incomparably heavier. Some mineralogists have taken it for an arfenical ore of tin % others for manganeSe, mixed with tin and iron. Meffrs. Del- huyars, who made a Stria analyfis of it, found it to contain manganefe 22, oxide 13*, quartaofe powder 2, yellow powder or tungftick acid 65. ; 9...C 4^2 'Aj/'oys ef Wolfram. The wolfram which was analySed by thefe chemifts, came Srom the tin mines of Zinuwalde, 01 the frontiers of Saxony aniBohemia. Its fpecifick gravity was 6.835. Wolfram does not melt by the blow-pipe without addition, its angles being fcarcely rounded. With the native phofphate, or microcofmick Salt, it melts with efferveScence, and affords a glafs of a hyacinth colour. It effervefces with Borax, and forms a greenifh yellow glafs m the blue flame. This glafs becomes red in the external flame. Pulverized wolfram upon which the muriatick acid is boiled, affumes a yellow colour like tungften. Meffrs. Delhuyars SuSed in a crucible two gros of pulverized wolfram, and four gros of pot-affi. The fufed mixture being pour- ed out on a plate of copper, a black matter remained in the crucible ; which, when well edulcorated, weighed thirty-feven grains, and was found to be a mixture of iron and manganefe. The mafs which had been poured out was diffolved in water, filtered, and Saturated with nitrick acid. It afforded a white precipitate, absolutely fimilar to that obtained from tungften by a fimilar procefs. The procefs of Scheele by the humid way, Succeeds equally well, and even appeared to Meffrs. Delhuyars to be more advan- tageous. They prefer the difengagement, by mere heat, of the ammoniack which holds the tungftick acid in Solution. One hundred grains of wolfram, treated with the muriatick acid and ammoniack, afforded them fixty-five grains of a yellow powder, Which is the pure acid. This yellow acid powder unites with moft of the metals. Meffrs. Delhuyars relate the following faas : 1. One hundred grains of gold leaf, and fifty grains of the yellow matter, urged by a violent heat for three quarters of an hour, in a crucible lined with charcoal, afforded a yellow button, which crumbled in pieces between the fingers, and internally exhibited grains of gold, with others of a grey colour. This button weighed one hundred and thirty-nine grains ; and was cupelled with'lead, though with difficulty. 2. Similar proportions of platina and the yellow matter, treat- ed in the Same way (Sor an hour and a quarter,) afforded a fria- ble button, in which grains oS platina were diftinguifhable, of a Whiter colour than ordinary. It weighed one hundred and forty grains. £. With filver, the yellow matter formed a button of a white greyiffi colOur, rather fpungy, which extended itfelf eafily by a few Strokes of the hammer -, but on continuing them, it Split in Alloys of Wolfram. W pieces. This button weighed cne hundred and forty-two grains, and the mixture was perfea. 4. With copper, it afforded a button of a coppery red colour, inclining to grey, which was fpungy, and confiderably duaile. It weighed one hundred and thirty-three grains. 5. With crude or caft iron, of a white quality, it afforded a perfea button, whofe fraaure was compact, and of a greyifh white colour. It was hard, brittle, and weighed one hundred and thirty-feven grains. 6. With lead, it afforded a button of an obfeure grey colpur, with very little brilliancy, fpungy, very duaile, and Splitting in- to leaves when hammered. It weighed one hundred and twen- ty-Seven grains. 7. The button Sormed with tin was oSa lighter grey than the preceding, very Spungy, Somewhat duaile, and weighed one hundred and thirty-eight grains. 8. The button "of antimony was of a bright grey, rather fpungy, brittle, and eafily broken ; it weighed one hundred and eight grains. 9. That of biSmuth preSented a fraaure which, when feen in one direaion, was oS a-grey colour, and metallick luftre ; but in another direaion it appeared like an earth without any luftre : but in both caSes an infinity oS pores were Seen over the whole maSs. It weighed Sixty-eight grains. 10. The button Sormed with zinc was of a black greyifh col- our, and an earthy aSpea, very Spungy, and brittle : it weighed forty-two grains. 11. With common manganeSe it afforded a button of a bluifh grey colour, and earthy aipect. Its internal part, examined with alens, refembled an impure fcoria of iron j it weighed one hun- dred and feven grains.* Thefe e::p-r;ments confirm the SuSpicion of the celebrated Bergmann : who, Srom the fpecifick gravity of this fubftance, and its property cf colouring the native phofphate and borate of foda, concluded thai it was of a metallick nature. The change of colour which accompanies its reduaion, its increafe of weight by calcination, its metallick aSpea, and its uniting with other metals, are incomeflable prooSs of its metal- lick nature. The yellow matter muft thereSore be confidered as a metallick oxide ; and the button obtained by expofing this oxide to a ftrong fire, with powder of charcoal, is a true metal. * In Cullen's Tranflation of the Chemical Analyfis of Wolfram, printed in London in 178;, 1 find the word brown in everyplace where M.Chap- taJ fus ijflJ the wotd gr//l or grey. Not having the original, fcannot Speak virr. certainty j but from circumilancts, conclude this Lit to be right. T ftcty. k Cofutming Molybdena. Meffrs. Delhuyars having put one hundred grains of the yel- low matter into a lined crucible well clofed, and expofed it to a ftrong heat for an hour and a half, found upon breaking the crucible, when cold, a button which was reduced to powder be- tween the fingers : its colour was grey. On examining it with the magnifier, an affemblage of metallick globules were feen, among which fome were of the bignefs of a pin's head, and when broken exhibited a metallick fraaure reSembling fteel. It weighed fixty grains and of courfe there was a diminution of forty. Its fpecifick gravity was 17.6. Having calcined a part pf ft, it became yellow with ^£ increafe of weight. The ni- trick and the nitro-muriatick acid changed it into a yellow pow* der. The fulphurick and muriatick acids diminished its weight, and their folution let Sail Pruffian blue. The metallick grains always remained after the aaion of thefe acids. This metal {hews various properties, which diftinguiffi it from all others knowri. 1. Its fpecifick gravity is 17.6. 2. It forms peculiar glafs with the feveral fluxes. 3. It is almoft absolutely inSu- Cbfe; much leSs fufible than manganefe. 4. Its oxide is of a yellow cqlour. 5. It forms peculiar alloys with the known met- als.* 6. It is infoluble in the fulphurick, muriatick, nitrick, and nitro-muriatick acids ; and thefe two laft convert it into an ox- ideT[" 7. The oxide combines with alkalis. 8. The oxide is in- foluble in the fulphurick, nitrick and muriatick acids, and af- fumes a blue colour with this laft. Wolfram ought to be confidered as an ore, in which this meN al is combined with iron and manganefe, as Meffrs. Delhuyars h^e proved.. CHAPTER XVII, Concerning Molybdena* < TWO fubftances have long been confounded together under the name of Black Lead Ore, Mineral Lead, Plumbago, and Mo- lybdena, which the more accurate analyfis of the celebrated Scheele-has proved to be oS a very different nature. Molybdena cannot be conSounded with the mineral of which black lead pencils are made, which is called Plumbago. The charaaeriftick differences are Sufficiently evident to leave no doubt on this SubjecT- ,. . Molybdena is compofed of Scaly particles, either, large or fmall, and flightly adherent to each other. It is SoSt and fat to Molybdena and its Oxide. 40* the touch, foils the fingers, and makes a trace of an affi grey colour. Its aSpea is bluifli, nearly refembling that of lead. The mark it makes on paper has an argentine brilliancy ; where- as thoSe oS plumbago are of a darker and leSs Shining colour j its powder is bluiffi ; by calcination it emits a Smell of Sulphur, and leaves a whitifh earth. The nitrick and the arSenical acid* are the only acids which attack it effeaually ; it is foluble in fo- da with efferveScence before the blow-pipe; it caufes the ni- trate of pot-affi to detonate, and leaves a reddiffi refidue ; whem expoSed to the flame of the blow-pipe in the Spoon, it emits a white Sume. Plumbago is leSs fat, leSs granulated, and eompoSed of fmall brilliant particles. It loSes in the fire Ty^. of its weight, and the refidue is an oxide of iron. Molybdena has been Sound in Iceland, in Sweden, in Saxony, in Spain, in France, &c. ; that of Iceland is found in plates, in a red feld fpar mixed with quartz. Mr. Haffenfratz gave Mr. Pelletier Samples of molybdena Sim- ilar to thofe of Iceland, which he had colfeaed in the mine named Grande Montagne de Chateau Lambert,near Tillot,where 3 copper mine was formerly wrought. William Bowles appears to have found molybdena near the village of Real de Monafterio ; it is in banks of grit ftone, Some- times mixed with granite. The molybdena of Nbrdberg in Sweden is accompanied with iron that obeys the magnet. The molybdena of Altemberg in Saxony nearly refembles that oS Nordberg. Mr. Pelletier analySed all theSe Species; and his work may be conSulted in the Journal de Phyfique Sor 1785 ; but the ex- eriments we Shall here relate were made .with that oS Altem- erg. Molybdena, expoSed to heat on a teft, becomes covered, af- ter the Space of an hour, with a white oxide; which, when col- feaed by a procefs fimilar to that ufed with the fublimed oxide of antimony, has all the appearances of this laft fubftance. The whole of the molybdena may by this means be converted into oxide. We are indebted to Mr. Pelletier for this fine experi- ment, which had efcaped'Scheele. Molybdena is indeftruaible in clofe veflels, and prodigioufly refraaory, according to the experiment of Mr. Pelletier, made with balls of porcelain expofed to the moft intenfe heat. Molybdena treated with the blac* flux was not reduced, nor even deprived of its fulphur. * 4** MtSybdena and its Oxide, Molybdena fufed with iron affords a button, which refemblea dobalt; it unices likewiSe perfeaiy with copper ; but when mix- ed, with lead andtin, k renders them fo refraaory that the re- fuhs are pulverulent and infufible alloys. i The oxide of molybdena obtained by calcination, or by the a&ion of the nitrick acid, is not reducible when treated with black flux, alkali, charcoal, or the other faline fluxes ; neverthe* lefs if the oxide of lead or copper be added, the metals which reSult are alloyed with a portion of molybdena, which may be feparated. . . The oxide of molybdena made into a pafte with oil, dried by the fire, put into a lined crucible, and urged by a violent heat for two hours, afforded Mr. Pelletier a Subftance flightly aggluti- nated, which could be broken with the fingers. It was black* but perceptibly of a metallick aSptdt. When viewed with the nHgnifter,. Small round grains of a greyifh metallick colour were feen, which are thie metal of molybdena. It is prodigioufly re- &a&ory.4 for the fire which Mr. Pelletier gave was Stronger than that which Mr. Darcet ufed in the Same forge to SuSe platina and manganeSe. - i. Molybdena-is calculable., and paffes to the ftate of a very white oxide. 2. It detonates with nitre, and the refidue is an oxide of manganefe mixed with alkali. 3. The nitrick acid cqnverts.it into'a white acid oxide. 4. The alkalis difengage hy- drog-cnous gas from k in the dry way, and the refidue is the ox-.; rde of manganeSe and alkali. 5. It alloys with the metals iri. different manners. Itsalloys with iron, copper,, and filver, are very Sriable. 6, When created with Sulphur it regenerates the. mineral molybdena. .According-to M** Kirwan, the mineral of molybdena containg $&y>five pounds fulphur, and forty-five metal. The iron is ac- cidental.- ■;_._ __ • ,( To reduce the mineral molybdeha to powder, Scheele direas that it be triturated in a mortar with a fmall quantity of fulphate of pot-aSk. The powder is aSterwards wafhed in hot water, to carry off the Salt, and the molybdena remains pure. This ore is a true pyrites, which when treated with the* Wow-pipe, emits a white acid fume. But as this method affords only a fmall quantity of oxide, another method is, ufed to obtain it. Thirty parts of nitrick acid are diS- tiifed on one.of powder of molybdena ; care being taken to-ufe a large retort, and to pour 4he acid on at feveral timesr hjKving previoufly diluted it with qne fourth- of; "water.. There-- eeiver being luted on, the*diftillation is perf£Tme4 on tjie fand- bath. When the fluid begins to boil, a confiderable quantity of Acid of Molybdena* 4*7 nif rous gas comes over. The diftillation being continued to dry- hefs, there remains a powder, upon which an additional dofe of riitHck acid is poured ; and this management is repeated until all the nitrick acid has been ufed. At the end of the proeefs there remains a refidue as white as chalk, which is to be waffied with water to carry off a fmall quantity of fulphurick acid, which ia formed by the decompofition of the nitrick acid upon the Sul- phur. After this edulcoration there remain fix gros thirty-fix grains of an acid powder, when the operation has been made with thirty ounces of nitrick acid, and one ounee Of molybdena. It is the molybdick acid. The arfenical acid diftilled from the mineral molybdena, like- wife affords the molybdick acid. >■ It is evidently feen that its formation, like that of the arfeni-: cal acid, is owing only to the decompofition of the acid made-; uSe oS, and the fixation of their oxigene on the metal employed* This acid is white, and leaves a perceptibly aeid and metall^ ick tafte on the tongue. Its fpecifick gravity compared with that of pure water is 3.460 : 1.000, according to Bergmann. It undergoes no alteration in the air. It does not rife in Sublimation, but by the affiftance of ih$ air. It colours the native phoSphate of a beautiful green. If it be diftilled with three parts of fulphur, the rnineral mo- lybdena is regenerated. This acid is foluble in five hundred and Seventy times its weight of water at a mean temperature; The folution is very acid ; decompofes the Solutions of foap $ precipitates the Sulphures of alkali. It becomes blue and con- sistent by cold. The concentrated fulphurick acid diflblves a large quantity of it. The folution affume3 a fine blue colour; andf becomes thicK by cooling. This colour disappears by heat, and returns again" as the fluid cools. The muriatick acid diflblves a confiderable quantity by the' affiftance of ebullition. IS the folution be diSttlled, it leaves a* refidue of an obfeure blue colour. By an increafe of heat, white" fublimate rifes mixed with a little blue ; the fuVning muriatick acid paffes over into the receiver. This fublimate attraas hu- midity, and is nothing but the molybdick acid volatilized by the muriatick. This folution of the molybdick acid precipitates filver, mercu- ry, and lead from their folutions in the nitrick acid. It likewiSe precipitates lead from its lbUition of the muriate of lead, bid* not the other metal*. 4<* 4cid of Molybdend, The molybdick acid takes barytes from the nitrick and muri-» atick acids. In the dry way it decompofes the nitrate of pot-afh, and * the muriate of foda ; and the acids pafs over in the fuming ftate. It diSerigages the carbonick acid from its combinations, and unites with the alkalis. It even partly decompofes the fulphate of pot-afh by the af- fiftance of a ftrong heat. It diflblves feveral metals, and affumes a blue colour in pro- portion as it yields its oxigene to them. The combinations of this acid with the alkalis are little known. Scheele however has obferved, that fixed alkali renders this acid earth more foluble in water ; that the alkali prevented the acid from rifing ; that the raolybdite of pot-affi is precipitated by cooling in fmall granulated cryftals. The oxigene adheres but flightly to the molybdick bafe : for this acid boiled with the femi-metals does not fail to affume a blue colour. Hydrogenous gas paffed through it is fufficient to produce the blue colour. Molybdena, as Mr. Pelletier has obferved, has great refem- blance in its chemical refults to antimony ; fince, like that femi- metal it is capable of affording by calcination an argentine ox- ide, capable of vitrification. t>ARt THE FOURTti. CONCERNING VEGETABLE SUBSTANCES. INTRODUCTION. X HE mineral bodies upon which we have hitherto treated, poffefs no liSe or vital principle, properly fjseaking j neither do they exhibit any phenomena dependant upon internal Organization. The cryftallization affeaed by Subftances of this , kingdom, appears to be exceedingly different from the organ!* zation of living beings. It produces no advantage to the indi- vidual ; and at moft ferves only to prove the great harmony ol nature, which marks its feveral produaiortS with conflant and invariable forms. But the organization of vegetable and animal beings difpofes thofe bodies in fuch a manner as is reSpeaivety the moft proper to accomplish the two final purpdSes of nature ; namely, the Subfiftence and reproduaion of the individual.* It cannot be denied that vegetables are endued with a prihci* pie of irritability, which developes in them both fenfation and motion : the motion is fo evident In certain plants, that it may be produced at pleafure, as in the fenfitive plant,, the Stamina Of the opuntia, &c. The plants which follow the courfe of the fun j thofe which in hot-houfes incline towards the apertures that admit the light; other plants Which contraa and Shut up by the punaure of an infea ; thofe whofe roots turn out of their direa or original courfe to plunge themfelves into a fa- vourable foil, or water—have not thefe a degree of fenfation of touch which may be compared to the Senfibility oS animals ? The difference of the Secretions in various organs, Suppofes a differ* ence in the irritability of each refpeaive part. The reproduaion of vegetables is effeaed in the fame man- ner as that of animals; and modern botanifts have Supported the comparison between theSe two funaions in the moft happy and conclufive manner. • * For the developement of th erries, fuch as the unauous property. Oils are diftinguiffied, relative to their fixity, into fat oils, *and effentialoils. We Shall deScribe them in this article under Athe names of Fixed Oils and Volatile Oils. The difference be- tween thefe two kinds of oils do not merely confift in their various degrees of volatility, but alfo in their habitudes with the feveral re-agents. The fixed oils are infoluble in alcohol, but the vola- tile oils are eafily diffolved : the fixed oils are in general mild ; • while the volatile are acrid and even cauftick. It appears nevertheless that the oily principle is the Same ia both; but it is combined with mucilage in the fixed oils, and 1 with the fpiritus rector, or aroma, in the volatile oils. By burn- ing the mucilage of fixed oils by diftillation, they become more and more attenuated ; the fame may likewife be done by means of water, which diffolves this principle. By diftilling volatile roil with a Small quantity of water, by the gentle heat of a water bath, the aroma is feparated, and this may be again reftored by re-diftilling it with the odorant plant which originally afforded if. Volatile oil is uSually found in the moft odorant part of any plant. In unbelliSerous plants it is Sound in the Seed; in the geum, the root affords it ; and in the labiated plants it is found in the branches and leaves. The fimilitude between volatile- oils and ether, which appears to be merely a combination of ox- igene and alcohol, proves that the volatile oils may be nothing but a combination oS the fermenteScible bafis of Sugar with oxi- gene. Hence we may form a notion how oil is formed in the diftillation of mucilage and of Sugar ; and we fhall no longer be furpriSed to find that the volatile oils are acrid and corrofive, that they redden blue paper, attack and deftroy cork, and ap- proach to the properties oS acids. We Shall now proceed te preat of fixed and volatile oils Separately. DIVISION I. Ppncerning Fixed Oils- Moft of the fixed oils are fluid ; but the greater number are capable oS palling to the Slate of folidity, even by a moderate degree of cold. There are fome which conftantly poffeSs that form in the temperature of our climates ; fuch as the butter of pacao, wax, and the pela of the Chinefe. They all congeal at different degrees of cold. Qiive oils become folid at 10° below zero of Reaumur ; oil of almonds, at the fame degree; but nut Ail does not freeze in our climates. Oil of Almonds. 42f The fixed oils poffefs a very evident degree of unauofity, do pot mix either with water or alcohol, are volatilized at a degree pS heat Superiourto that of boiling water, and when volatilized they take fire by the contaa of an ignited body. The fixed oils are contained in the kernels of fhell fruits or nuts; in the pippins, and fometimes in all the parts of fruits, fuch as olives and almonds, all whofe parts are capable of afford- ing them. The oil is ufually made to flow by expreflion out of the cellules which contain it: but each fpecies requires a different manage- ment. i. Olive oil is obtained by expreflion from the fruit of the olive tree. The procefs ufed by us is very fimple. The olive is cruffied by a mill ftone, placed vertically, rolling upon an horizontal plane. The pafte thus formed is ftrongly preffed in a prefs ; and the firft oil which comes out is called Virgin Oil. The marc or pulp is then moiftened with boiling water ; the mafs is again preffed j and the oil which floats upon the water carries with it part of the parenchyma of the fruit, and a great part of the mucilage, from which it is difficultly cleared. The difference in the kind of olive produces a difference in the pil ; but the concurrent circumftances likewife eftabliffi other differences. If the olive be not fufficiently ripe, the oil is bitter; if it be too ripe, the oil is thick and glutinous. The method of extracting the oil has a very great influence on Its quality. The oil mills are not kept fufficiently clean ; the mill Stones, and all the utenfils, are impregnated with a rancid oil, which cannot but communicate its flavour to the new oil. In fome cou- tries it is ufual to lay the olives in heaps, and fuffer them to ferment before the oil is drawn. By this management the oil is bad ; and this procefs can only be ufed for oil intended for the lamp ©r for the Soap boiler. 2. OH of almonds is extraaed from that fruit by expreflion. For this purpofe dry almonds are put into a coarfe fack, and ag- itated rather ftrongly, to difengage an acrid powder which ad- heres to the Skill- They are then pounded in a marble mortar into a pafte, whfeh is wrapped in a coarfe cloth, and fubjeaed to the prefs. This oil is greeniffi and turpid when frefh, becaufe the aaion pf the prefs caufes part of the mucilage to pafs through the cloth; as it becomes older it is clearer, but is acrid by the decom- pofition of the fame mucilage. Some perfons throw almonds into hot water, or expofe them to fteam, be lore they prefis them j but this addition of water difpoSes the oils to become rancid more Speedily. 43? Oil of Afmondj. IJy this pr*cej(s the oil of all kinds, of ajbaond* nuts, and feeds, isay be,extracted. 3. Linfeed oil is extraaed from the feed of the plant linun*. As this feed contains much mucilage, it is torrefied before k is fot>je£ted to the prefs. This previous, treatment gives the oil a disagreeable enapyjeumatick favour ; but at the Same time de- rives it of the property of becoming rancid, and renders it one of the moft drying oils. All mucilaginous Seeds, all kernels, and the Seeds of henbane and of the poppy, ought to be treated iMhe fame manner. If a fat oil be diftilled in a proper apparatus of veflefe, the pjeodua is*phlegm \ an acid; a fluid or light oil, which becomes thicker towards the end ; much hydrogenous gas, mixed with carbonick acid ; and a coaly refidue, which affords no alkali. I have obServed that the volatile oils afford more hydrogenous gas, and the fixed more carbonick acid : this laft product depends on the mucilage. By diftilling the fame oil repeatedly, it is more and more attenuated, becomes very limpid and very vola- tile, with the only difference it has required the peculiar odour communicated by the fire. The volatilization of the oil may be accelerated by diftilling it from an argillaceous earth ; by this means it is in a Short time deprived of its colouring part: and the heavy oils which afford bitumens, when diftilled once or twice from clay alone, Such as that of Murviel, are rendered per- feaiy colourlels. The ancient chemifts prepared oleum philqfo- phorum by diftilling oil from a brick previously impregnated with it* i. Oil e^fih/ combines with oxigene. This combination is cither flow or rapid. In the firft cafe, rancidity is the confe- quence ; in the fecond inflammation. Fixed oil expoSed for a certain time to the open air, abSorbs the oxigenous gas, and acquires a peculiar odour of fire, an acrid and burnt tafte, at the Same time that it becomes thick and coloured. If oil be put in contaa with oxigene in a bottle, k becomes more fpeedily rancid, and the. oxigene is abforbed* Scheele obServed the abSorption of a portion or" the air before the theory was well afcertained. Oil is not fubjea to alteration m cloSed veflels. It Seems that oxigene, combined with the mucilage, confti* tutes rancidity ; and that, when combined with the oil itSelf, it forms drying oil. The rancidity of oils is therefore an effea analogous to the calcination or oxidation of metals. It effentially depends on the combination of pure air with the extraaive principle, which is naturally united with the oily principle. We may carry this Petrification tf Oris. 431 inference to demonstration, by attending to the pToceffes ufed to counteraa or prevent the rancidity of oils. A. When olives are prepared for the table, every endeavour is ufed to deprive them of this principle, which determines their fermentation ; and for this purpofe various methods are ufed. In fome places they are macerated in boiling water, charged with Salt and afomatieks; and, after twenty-four hours digeftioti, they are Steeped in dear water, which is renewed till their tafte is perfeaiy mild. Sometimes nothing more is done than to macerate the Olive? in cold water ; but they are frequently ma- cerated in a lixivium of quick-lime and wood afhes, after which they arft Wafhed in ckeaf water. But in whatever manner the preparation is made, they are preferved in a pickle charged with fome aromatick plant, fuch as coriander and fenhel. Some per- fons preferve them whole; others Split them, for the mfcrc complete extraaion of their mucilage, and in order that they may be more perfeaiy impregnated with the aromaticks. All theSe profeffes evidently tend to extraa the mucilaginous principle, which is Soluble in water, and by this means to pre- ferve th* fruit From fermentation. When the operation is not Well made, the olives ferment and change. If olives be treated With boiling water, to extraa the mucilage, before they are Submitted to the prefs> a fine oil will be obtained, without dan» get of taftcidity. S. When the oil is made, if it be ftrongly agitated in wa. ter, the mucilaginous principle is difengaged ; and the oil may be afterwards preferved for a long time without change. I have preferved oil of the marc of olives, prepared in this man- ner, for feveral years, in open bottles, without any alteration. C. The torrefaaion to which feveral mucilaginous feeds art fubjeaed before the extraaion Of the oil, renders them lefs fuf* Ceptible of change, becaufe the mucilage has been deftroyed. D. M. Sieffert has propoSed to ferment oils with apples or pears, in order to deprive rancid oils of their acrimony. By this means they are cleared of the principle which had combin- ed with them, but now becomes attached to other bodies. Mucilage may therefore be confidered as the feed of fermen- tation. When the combination of the pure air is favoured by the vol- atilization of the oil, inflammation and combuftion are then fhe Confequence. To carry this combination into effea, the Oil ihuft be volatilized by the application of a heated body; and the flame which is produced is then fufficient to maintain the de- gree of volatility, and fupport the combuftion. When a Current •f air is caufed to pafs through the middle of the wick and the 43l Combinations of 0/7/. flame, the great quantity of oxigene which muft then neceflarU ly pafs, occafions a more rapid combuftion. Hence it is that the light is Stronger, and without Smoke; for this is deftroyed and conSumed by the violent heat which is excited. The lamps of Palmer are likewiSe entitled to our particular attention. By caufing the rays to pafs through a liquor colour- ed blue, he perfeaiy imitates the light of the day; which proves that the artificial rays require to be mixed with the bluej to imitate the natural ; and the folar rays which pafs through the atmofphere, may owe their colour to their combination with the blue colour which appears to predominate in the air. If water be projeaed upon oil in a State of inflammation, it is known that extinaion does not happen, becaufe the water is decompofed in this experiment. If the produa of the com- buftion of oil be colfeaed, much water is obtained, becaufe the combination of its hydrogene with oxigene produces that fluid. Mr. Lavoifier has proved that one pound of olive oil contains, Coal or carbone, 12 ounces, 5 gros, 5 grains ; Hydrogene, 3 2 67. The art of rendering oils drying, likewife depends on the combination of oxigene with the oil itfelf. For this purpofe, nothing more is required than to boil it with oxides. If an oil be heated upon the red oxide of mercury, a confiderable ebulli- tion enfues, the mercury is reduced, and the oil becomes very drying : this is an obfervation of Mr. Puyiriaurin. The oxides of lead or copper are commonly ufed for this purpofe. An ex- change of principles takes place in this operation ; the mucilage combines with the metal, while the oxigene unites with the oih Oil may likewife be combined with the metallick oxides by double affinity, after the manner of Berthollet. For this pur- pofe a Solution of foap Is poured into a metallick folution. By this means a foap of a greea colour is prepared with a fulphate of Copper j and, with that of iron, a foap of a deep brown col- our, of confiderable intC'firy. It appears that, in the combinations of fixed.oils with the ox- ides of lead, a fubftance is difengaged, and fwims at the top, which Scheele called tii- Sw.et Principle, and feems to be fim- ply mucilage. 2. Oil combines with Sugar, and affords a kind of foap, which may be eafily diffufed in water, and kept SuSpended. The trituration oS almonds with Sugar and water, forms the lac amygdale, orgeat, and other emulfions. Combinations of this kind exift ready formed in the vegetable kingdom. 3. Oil unites read'ty with alkalis; and the refult of this un-* ion is the well-known compound, foap. Te this eieapot-afh, ManufaBure of Soaps. 433 •V pure alkali may be triturated with oil, and the mixture con- centrated by fire. The medicinal Soap is made with oil oS Sweet almonds, and halS its weight oS pot-affi or cauftick alkali. The Soap becomes hard by ftanding. To make the Soap oS commerce, one part oSgood Soda of Al- icant muft be boiled with two of quicklime, ,in a fufficient quantity of water. The liquor is then to be ftrained through a cloth ; and evaporated to that degree, that a phial which con- tains eight of pure water, may hold eleven of the faline folution, which is ufually called Soap Lye or Lees. One part of this lixivium, and two of oil, boiled together, till upon trial with a Spatula it eafily Separates, and Soon coagulates, Sorm Soap. In moft manuSaaories the lixivium is prepared without heat. Equal volumes of pounded foda of Alicant, and quicklime pre- vioufly flacked, are mixed together. Water is thrown on this mixture, which filters through, and is conveyed into a proper veffel. Water is poured on till it paffes through without ac- quiring any more fait. In this way thefe kinds of lyes are ob- tained, which differ in ftrength ; that which paffes firft is the ftrongeft, and the laft is almoft mere water. Thefe are after- wards mixed with oil in boilers, where the mixture is favoured by heat. The weak lye is firft added, and afterwards gradually the Stronger ; and the ftrongeft is not added till towards the end of the procefs. To make the foap marbled, they make ufe of foda in the mafs, blue copperas, cinnabar, Sec. according to the colour defired. A liquid green or black foap is likewife made by boiling the lixivium of foda, pot-affi, or even wood afhes, with the marc of the oils of olive, of nuts, or of nape ; or with fat, or fiffi oil, &c. The black Soap is made in Picardy, and the green in Hol- land. The Marquis de Bouillon has propoSed to make Soaps with animal Sat. At Aniane, in the neighbourhood of Montpellier, a foft foap is prepared with cauftick lixivium of wood afhes, and the oil or the marc of olives. If foap be expofed to diftillation, the refult is water, oil, and much ammoniack; and there remains in the retort a large quan- tity of the alkali ufed in the fabrication of the foap. The am- moniack which is produced in this experiment appears to me to arife from the combination of the hydrogenous gas of the oil with the nitrogene, a conftituent principle of the fixed alkali. Soap is foluble in pure water; but it forms curds, and is de- compofed in water abounding with fulphates : becaufe the ful- phurick acid feizes the alkali of the foap ; while the earth com- bines with the oil, and forms a foap which Swims at the furface. 3-G 434 FffieBs of Acids on Oils. Soap is likewife foluble in alcohol by the affiftance of a gentle heat; and forms the eflence of foap, or opodeldock, which may be feemed at pleafure. Soaps are capable of combining with a larger quantity of oil, and rendering it foluble in. water. Hence their property of cleanfing cloth*,, linens, &c. They are uSed as deobftruents in medicine. 4. The fixed oils unite likewiSe with acids. Meffrs. Achard, Cornette, and Macquer, have attended to theSe combinations. Achard gradually adds the concentrated Sulphurick acid to the fixed oil; the mixture being triturated, a mafs is obtained which is Soluble in water and in alcohol. The fuming nitrick acid immediately turns the fixed oils black, and fets fire to fuch as are drying. It is in this cafe decompofed with a rapidity fo much the greater, as the oil has a greater af- finity with the oxigene. On this account it is that the inflam- mation of the drying oils is more eafily effeaed than that of the others. Thofe acids whofe conftituent parts adhere moft ftrongly to- gether, have but a very feeble aaion on oils; a circumftance which proves that the effea of acids upon oils is principally owing to the combination of their oxigene. It is by virtue of this Strong affinity of oils with oxigene, that they poffefs the power of reviving metals. The oxigene then quits the metal, and unites with the oils, which become thick and coloured. It likewife follows from hence that drying oils ought to be preferred for this ufe ; and we find that praaice agrees with theory in this refpea. DIVISION II. Concerning Volatile Oils. Fixed oil is combined with mucilage, volatile oil with the fpiritus reaor, or aroma ; and it is this combination or mixture which constitutes the difference between them. The volatile oils are charaaerized b> a ftrong Smell, more or leSs agreeable ; they are Soluble in alcohol, and have a penetrating and acrid tafte. All the aromatick plants contain volatile oil, excepting thoSe whoSe Smell is very tranfient, Such as jeffamine, violets, lilies, &c. The volatile oil is fometimes diftributed through the whole plant, as in the Bohemian angelica ; fometimes it exifts in the bark, as in cinnamon. Balm, mint, and the greater abfin- thium, contain their oils in the Item and leaves ; elicampane, the iris of Florence, and the caryophyllata, in the root. All. Volatile or Effential Oils. 435 the refinous trees contain it in their young branches; rofemary, thyme, and wild thyme, contain their efferrtial oils in their leaves and buds ; lavender, and the roSe, in the calyx oS their flowers j camomile, lemon, and orange trees, in the petals. Many Sruits contain it through their whole Subftance, Such as pepper, juni- per, Sec. Oranges and lemons in the zeft and peeling which incloSe them. The Seed oS umbelliSerous plants, Such as anniSe and Sennel, have the veficles of effential oil arranged along the projeaing lines on their fkin : the nutmeg tree contains its effen- tial oil in the nut itSelS.—See L'IntroduBion a /' Etude du Regne Veg. par M. Buquet. p. 209—212. The quantity oS volatile oil varies according to the ftate of the plant. Some afford moft when green, otbers when dry ; but fhe latter conftitute the fmallett number. The quantity likewiSe varies according to the age of the plant, the foil, the climate, and the time of extraaion. The volatile oils likewife differ in their confiftence. Some are very fluid, as thofe of lavender, rofemary, and rue ; the oils of cinnamon and faflafras are thicker; there are fome which con- stantly preferve their fluidity : others which become concrete by the flighteft impreffion of cold, as thofe of annifeed and fennel: others again poffeSs the concrete Sorm, Such as thoSe oS roSes, of parfley, and of elicampane. The volatile oils likewife vary in their colour. The oil of rofes is white ; that of lavender, of a light yellow : that of cin- namon, of a brown yellow ; the oil of camomile is of a fine blue ; that of millefoil, of a fea-green ; that of parfley, green, &c. The weight is likewife different in the different kinds. The oils of our climates are in general light, and fwim upon water ; others are nearly of the fame weight; and others are heavier, Such as the oils oS SaffaSras and oS cloves. The Smells oS effential oils vary according to thoSe of the plants which produce them. The tafte of the volatile oils in general is hot; but the tafte of the plant does not always influence that of the oil; for ex- ample, the oil of pepper has no acrimony, and that which is obtained from wormwood is not bicter. We are acquainted with two methods of extraaing the vola- tile oils—expreflion and diftillation. 1. Thofe oils which are, as it were, in a naked ftate, and con- tained in projeaing and vifible receptacles, are obtained by ex- preflion. Such are thoSe of citrons, oranges, cedrat, and berga- motte ; the oil iffues out of the fkin of thefe fruits when preffed. It may therefore be procured by a ftrong preffure of the peeling 436 ExtraBion of Volatile Oils. againft an inclined glafs. In Provence and in Italy they art rafped ; by which means the veficles are torn, and the oil flows into the velfel deftined to receive it: this oil Suffers the parenchy- ma which goes along with it to fubfide, and becomes clear by Handing. If a lump of fugar be rubbed againft thefe veficles, it imbibes the volatile oils; and forms an olco-faccharum, foluble in water, and very proper to give an aromatick flavour to certain liquids. 2. Diftillation is the method moft commonly ufed in the ex- traction of volatile oils. For this purpofe, the plant or fruit v/hich contains the oil is placed in the boiler or body of the alembick. A quantity of water is then poured in, fufficient to cover the plant, and the water is heated to ebullition. The oil which rifes with this degree of heat, comes over with the water, and is colfeaed at the furface in a particular receiver, called the Italian receiver, which fuffers the furplus of water to efcape by a fpout ifluing from the belly of the veffel, whofe orifice is low- er than that of the neck of the receiver; fo that by this means the oil is colfeaed in the neck, without a poffibility of its eSr caping. The water which paffes over in diftillation is more or lefs charged with oil, and the odorant principle oS the plant, and Sorms what is known by the name of Diftilled Water. Thefe waters ought to be returned again into the cucurbit when the Same kind of plant is again diftilled ; becaufe, being Saturated with oil, and the aromatick principle, they contribute to aug- ment the ulteriour prod udt. When the oil is very fluid or very volatile, it is neceffary to annex a worm pipe to the alembick, and to have the precaution of keeping the water at a very cold temperature ; but when, on the contrary, the oil is thick, the worm pipe muft be remov- ed, and the water of the reSrigeratory kept at a moderate tem- perature. In the firft way, the oils of; balm, mint, fage, laven- der, camomile, Sec. may be diftilled ; and by the fecond, the oils cf rofes, of elicampane, of parfley, of fennel, of cumin, &c. The oil of cloves may likewife be extracted by diftillation per defeenSum, which is determined by applying the fire above the material. . . Volatile oils are very Subjea to be adulterated, either by mix- ture with Sat oils, or with other effeimal oils, Such as that oS tur- pentine, which is cheaper ; or by mixing them with alcohol. In the firli caSe the fraud is eafily deteaed—i. By diftillation, be- cauSe volatile oils riSe at the heat of boiling water. 2. By cauf- ing blotting paper to imbibe fome of the mixture, and expofing !l 10 a decree ox heat Suorient to drive oft" the volatile oil. 3. Properties of Volatile Oils. 437 By means of alcohol, which becomes turbid and milky by the infolubility of the fixed oil. The volatile oils which have a very ftrong fmell, fuch as thofe of thyme and lavender, are often fophifticated by oil of turpentine. In this cafe the fraud may be difcovered by Soaking a fmall piece of cotton in the mixture, and leaving it expofed to the air a fuf- ficient time for the fmell of the good oil to be diffipated, and leave only that of the adulteration. The fame end may be an- fwered by rubbing a fmall quantity of the mixture on the hand, in which the peculiar fmell of oil of turpentine is developed. Thefe oils are likewife falfified by digefting the plant in oil of ol- ive before diftillation. In this manner the oil of camomile is prepared. The very light oils, fuch as thofe of cedrat or bergamotte, are often mixed with a fmall quantity of alcohol. This fraud is ea- sily deteaed by the addition of a few drops of water, which im- mediately become white, becaufe the alcohol abandons the oil to unite with the water. The volatile oils are capable of uniting with oxigene, with al- kalis, and with acids. 1. Volatile oils abforb oxigene with greater facility than the fixed oils. They become coloured by the abSorption, grow thicker, and pafs to the ftate of refin ; and when they are thickened to this point, they are no longer capable of ferment- ing, but fecure from all putrefaaion fuch bodies as are pene- trated and well impregnated with them. On this is founded the theory of embalming.—The aaion of acids upon thefe oils, cau- fes them to pafs to the ftate of refin ; and there is no other dif- ference between volatile oil and refin, than that which arifes from this addition of oxigene. All the oils, when they affume the charaaer of refin by this combination oS oxigene, fet Sail needle-Sormed cryftals oS cam- phor. Mr. Geoffroy has obServed them in the oil of fever-few, marjoram, and turpentine. Acad. 1721, p. 163. When the oil is changed by the combination of oxigene, it gradually lofes its fmell and volatility. To reftore this oil to iiS original ftate, it is diftilled. A thick matter remains in the diftilling veffel, which confifts oS refin perfeaiy formed and is thus feparated from the oil, which ha§ not yet undergone the fame alteration. 2. The habitudes oS acids are not the Same with all volatile oils. 1. The concentrated Sulphurick acid thickens them : but, if it be diluted, it forms iavonules. 2. The nitiick acid, when concentrated, inflames them ; bur, when diluted, it caufes them gradually to pafs to the ftate of refin. Borrichius appears to 43' Camphor. have been the firft who inflamed oil of turpentine with the ful- phurick acid, without the nitrick acid. Homberg repeated this delicate experiment with the other volatile oils. The inflamma- tion of oik is fo much the more eafily effeaed, aS the oil is more drying or greedy of oxigene, and the acid more eafily de- compofed. 3. The muriatick acid reduces oils to the Saponace- ous ftate, but the oxigenated muriatick acid thickens them. 3. Starkey appears to have been one of the firft who at- tempted to combine a volatile oil with a fixed alkali. His pro- ceSs is long and complicated, like thoSe of the alchemifts ; and the combination it afforded was known by the name of Starkey's Soap ; the procefs of this chemift was So long merely becauSe , he uSed the carbonate of pot-afh, or mild vegetable alkali; but if ten parts of cauftick alkali, or lapis caufticus, be triturated hot with eight parts of oil of turpentine, the foap is inftantaneoufly formed, and becomes very hard. This is the procefs of JMr. Geoffroy.—Acad, des Sciences, ann. 1725. Concerning Camphor. Camphor is obtained from a fpecies of laurel which grows in China and Japan. Some travellers affirm that the old trees contain it fo abundantly, that on fplitting the trunk it is found in large tears, fo pure as to have no need of reaification. To extracl the camphor, the roots of the trees are ufually chofen ; or, in want of thefe, all the other parts of the tree. Thefe are put, together with water, into an iron alembick, which is covered with its head The capital is fitted up internally with cords of rice ftraw, the joinings are Juted, and the diftillation proceeded upon. Part of the camphor Sublimes, and attaches itfelf to the Straw within the head ; while another portion is carried into the receiver with the water. The Hollanders purify camphor by mixing an ounce of quick-lime with every pound of the fub- ftance, and fubliming it in large glafs veffels. Camphor, thus purified, is a white concrete cryftalline Sub- stance, of a ftrong fmell and tafte, foluble in alcohol, burning with a white flame, and leaving no refidue : reSembling volatile oils in many reSpeas, but differing Srom them in certain proper- ties ; Such as that of burning without a refidue ; of diffolving quietly, without decompofition or alteration, in acids ; and of- being volatilized by a gentle heat, without change of its nature. Camphor is obtained by diftillation from the roots of zedoa- ry, thyme, rofemary, Sage, the inula helenium, the anemony, the pafque flower or pulSatilla, &c. And it is to be obServed, Properties of Camphor. 43 '■) that all thefe plants afford a much greater quantity of camphor when the fap has been fuffered to pafs to the concrete ftate, by a deficcation of feveral months. Thyme and peppermint, flow- ly dried, afford much camphor ; whereas the frefh plants afford volatile oil : moft of the volatile oils, in paffing to the ftate of refin, alfo let fall much camphor. Mr Achard has likewife ob- ferved that a fmell of camphor was difengaged when he treated the volatile oil of fennel with acids. The combination of the diluted nitrick acid with the volatile oil of anife, afforded him a large quantity of cryftals, which poffeffed moft of the proper- ties of camphor. He obtained a Similar precipitate by pouring the vegetable alkali upon vinegar faturated with the volatile oil: of angelica. From all htefe faas, it appears, that the bafe of camphor forms one of the conftituent principles of fome volatile oils ; but it is in the liquid ftate, and does not become concrete but by combining with oxigene. Camphor is capable of cryftallization, according to Mr Ro- mieu, whether in fublimation, or when it is flowly precipitated from alcohol, or when alcohol is fuperfaturated with it ; it pre- cipitates in flender filaments, cryftallizes in hexagonal blades at- tached to a common axis, and it fublimes in hexagonal pyra- mids or in polygonal cryftals. Camphor is not foluble in water ; but it communicates its fmell to that fluid, and burns on its furface. Romieu has ob- ferved that fmall pieces of camphor, of one third or one fourth of a line in diameter, being placed on the furface of pure water in a glafs, have a rotatory motion : and this appears to be an? efearical phenomenon ; for the motion ceafes if the water be touched with a conduaing fubftance ; but continues if it be touched with an infulating body, fuch as glafs, fulphur, or re- fin*. Bergen has obServed that camphor does not turn upon hot water. Acids diffolve camphor without producing any alteration in it, or becoming themfelves decompoSed : the nitrick acid dif- folves it quietly ; and this Solution has been called Oil oS Cam- phor. Camphor precipitated from its Solution In acids by the addition of alkalis, is heavier, hardet, and much lefs combufti- ble, according to the experiments of Mr. KoSegarten. By dif"- tilling the nitrick acid Several times Srom this Subftance, it ac- quires all the properties oS an acid which cryftallizes in parallel- opipedons. To obtain the camphorick acid, nothing more is required than to diltll the acid at Several times Srom the cam- phor, and in a large quantity. Mr. KoSegarten diftilled the ni- trick acid eight times Srom camphor, and obtained a Salt cryftal- 44° Ufes, &c. of Camphor. lized in parallelopipedons, which reddened the fyrup of violets^ and the tinaure of turnfole. Its tafte its bitter ; and it differs from the oxalick acid in not precipitating lime from the muri- atick acid. With pot-afh it forms a Salt which cryftallizes in regular hex- agons. With Soda it affords irregular cryftals. With ammoniack it Sorms cryftalline maffes, which exhibit Cryftals in needles and in priSms. With magnefia it produces a white pulverulent Salt, which may again be diffolved in water. It diffolves copper, iron, biSmuth, zinc, arSenick, and cobalt. The Solution of iron affords a yeilowifh white powder, which is inSoluble. This acid forms, with manganeSe, cryftals whoSe planes are parallel, and in Some reSpeas reSemble baSaltes. The camphorick acid, or rather the radical of this acid, exifts in Several vegetables ; fince camphor may be extraaed Srom the oils oS thyme, of cinnamon, of turpentine, of mint, of feverfew, of faffafras, &c. Mr. Dehne has obtained it from the pafque flower, or pulfatilla ; and Cartheufer has indicated feveral other plants which contain it. Alcohol readily diffolves it, and it may be precipitated by wa- ter alone : this folution is known in pharmacy by the name of Camphorated Spirit of Wine, or Camphorated Brandy, when brandy is the folvent. The fixed and volatile oils likewife diffolve each other by the affiftance of heat; the folutions let fall cryftals in vegetation, fimilar to thofe which are formed in the folutions of fal-ammo- niack, compofed of very fine filaments adhering to a middle part. This obfervation was made by Mr. Romieu. Acad, des Sciences, 1756. Camphor is one of the bed remedies which the art of medi- cine poffeffes. When applied to inflammatory tumours, it is re- Solvent ; and, internally taken, it is antiSpaSmodick, eSpecially when diffolved in brandy. It is given in Germany and in En- gland in the doSe of feveral drams per day ; but in France our timid phyficians do not preScribe it in a larger doSe than a Sew grains. It mitigates heat in the urinary paffage. It is given triturated with yolk oS egg, Sugar, &c. It has likewiSe been SuppoSed that its Smell deftroyed or drove away moths, and other inSeas which feed upon cloth, &c. Reftnous Subfaneee.. 44* ARTICLE III. Concerning Refins, The name oS Refin is ufed to denote inflammable Subftances foluble in alcohol, uSually affording much Soot by their combuft- ion ; they are Hkev/iSe Soluble in oils, but not all in water. All the refins appear to be nothing elSe but oils rendered concrete by their combination with oxigene. The expoSure of theSe to the open air, and the decompofition of acids applied to them, evidently prove this conclufion. Refins in general are leSs Sweet than the balfams. They af- ford more volatile oil, but no acid by diftillation. There are Some among the known refins which are very pure and perfeaiy Soluble in alcohol, Such as the balm oS Mecca and oS Copahu, turpentines, tacamahacaj elemi : others are leSs pure, and-contain a Small portion of extraa, which renders them not totally foluble in alcohol ; fuch are maftick, Sandarach guaiacurri, laudanum, and dragon's blood. i. The balSam of Mecca is a fluid juice which becomes thick and brown by age. It flows from incifions made in the amyris opobalfamum. It is known by the different names of Balm of judea, of Egypt, of Grand Cairo, of Syria, of Conftantinople, &c. Its fmell is ftrong, and inclining to that of lemons ; its tafte is bitter and aromatick. This balfam, diftilled by the heat of boiling water, affords rnuch volatile oil. -- ( It k balfamick ; and is given incorporated with fugar, or rhixed with the yolk of egg. It is aromatick, vulnerary, and hewing. 2. The balfam of Copahu flows from a tree called Copaiba in South America, near Tolu. It affords the fame produas, and poffeffes the fame virtues, as the foregoing. 3. The turpentine of Chios flows from the turpentine tree, which affords the piftachios. It is fluid, and of a yeilowifh white colour inclining to blue. This-plant grows in Cyprus, at Chios, and Is common in the South of France. The turpentine is obtained only from the trunk and large branches. Incifions are made firft at the low- er parts of the tree, and afterwards by degrees higher up. This turpentine, diftilled on the water-bath, without addition affords a very white, very limpid, and very fragrant volatile oil: a more ponderous oil may be extraaed at the heat of boiling water ; and the refidue which is called Boiled Turpentine,, af- 3...H 44* Various Refmous Subftances. fords by diftillation, in the reverberatory furnace, a weak acid, a Small quantity oS brcwn confiltent oil, and much coal. The turpentine of Chios is very rare in commerce. Venice turpentine is extracted from the larix : its colour is a bright yellow, its confiftence limpid, its fmell ftrong and aromatick, a:id its tafte bitter. The tree which affords it is that which affords manna. Holes are bored during the Summer near the bottom of the trunks of thefe trees, into which Small gutters or tubes are inSerted, to convey the juice into veffels intended to receive it. The refin is obtained only from trees in full vigour ; the old trees very often have confiderable depofitions of refin in their trunks. " This turpentine affords the fame principles as that of Chios. It is ufed in medicine as a detergent for ulcers in the lungs, kidneys, &c. either incorporated with Sugar, or mixed with the yolk of an egg to vemfer it more miScible with aqueous potions. The Soap of Starky, which we have Spoken of under the article of Volatile Oils, is made with this turpentine. The refin known in commerce by the name of Strafburgh Turpentine, is a refmous juice of the confiftence of a fixed oil, of a yeilowifh white colour, a bitter tafte, and a more agreeable fmell than the preceding refins. It flows from the yew-leaved fir, which is very common in the mountains of Switzerland. This refin is colfeaed in blifl- ers, which appear beneath the bark in the ftrong heats of fum- mer. The peafants pierce thefe veficles with the point of a fmall horn, which becomes filled with the juice, and is from time to time emptied into a larger veffel. The balm of Canada differs from the turpentine of the fir in its fmell only, which is more pleaSant. It is obtained from a fpecies of fir which grows in Canada. t % Oil of turpentine is more particularly ufed in the arts-. It is the great folvent for all refins ; and, as it evaporates, it leaves them applied to the furface of bodies on which the mixture has been fpread. As refins ar_ the bafis of all varnifhes, alcohol and oil of turpentine muft be the vehicles or folvents. 4. Pitch is a refinous juice of a yellow colour, more or lefs inclining to brown. It is afforded by a fir named Picea or E- picea. Incifions are made through the bark ; and the wound is renewed from tim? to time, as the lips become callous. A vigorous tree often affords forty pounds. Pitch melted, and expreffed through bags of cloth, is render- ed purer. It is packed in barrels, by the name of White Pitch, or Burgundy Pitch. White pitch mixed with lamp black, forms black pitch. Various Refmous Subftances. 443 White pitch kept in fufion becomes dry. The deficcation may be facilitated with vinegar, and leaving it for a time over the fire. It then becomes very dry, and is called Colophony. Lamp-black is the foot of burned pitch. It is likewife pre- pared by collecting the foot of pit-coal. 5. Gallipot is a concrete refirious juice, of a yeilowifh white colour and ftrong fmell. This juice comes from Guienne, where it is afforded by two fpecie^s of pine, the pinus tnaritima major, et minor. When thefe trees have acquired a certain Size, a hole or notch is cut through the bark, near the bottom of the trunk. The refin iffues out, and flows into veffels placed beneath to receive it. Care is taken to keep the wound open, and to renew it. The refin flows during the Summer ; but that which iffues out during the fpring, autumn, and winter, dries againft the tree. The Pine likewife affords tar, and the oil called huile de Cade, For this purpofe the wood of the trunk, branches, and roots, is heaped together and covered with turf, over which a fire ,is lighted, as if to convert them into charcoal. The oil which is difengaged, not being at liberty to efcape, falls to the bottom in- to a channel or gutter, which conveys it into a tub. The moft fluid part is fold under the name of huile de Cade ; and the the thicker part is the tar ufed for paying or painting the parts of Shipping and other veffels. The combinations of feveral refins, coloured by cinnabar and minium forms fealihg-wax. To make the wax, take half an ounce of gum-lac, two drams of turpentine, the fame qu antity of colophony, one dram of cinnabar, and the fame quantity of minium. The lac and and the colophony, are to be firft fufed, after which the turpentine is to be added, and laftly the colour*. ing matters. 6. Maftick has the form of white tears of a farinaceous ap- pearance, having little fmell, and a bitter aftringent tafte. Maf- tick flows naturally from the tree, but its produce is accelerated by incifions. The leffer turpentine tree, and the lentifcus, af- ford that which is met with in commerce. Maftick affords no volatile oil when diftilled with water. It is almoit totally foluble in alcohol. This refin is ufed in fumigations. It is chewed, to ftrengtfi- en the gums ; and it forms the bafis of feveral drying var- niffies. 7. Sandarach is a concrete refinous juice, in dry white tranf- parent tears, oS a bitter and aftringent taite. It is obtained Srom moft Species oS the juniper, and is Sound between the bark and the wood. 444 Balfams. Sandarach is almoft totally foluble in alcohol, with whichi It forms a very white varniffi, that dries Speedily. For this reaSon, the refin itSelfis known by us under the name of Varniffi, (vernis.) 8. Labdanum is a black refinous juice, dry and friable, of a ftrong Smell, and a diSagreeable aromatick tafte. It tranSudes from the leaves and branches of a kind of ciftus, which grows in the ifland of Candia. Tournefort, in his Voyage to the Le- vant, informs us that when the air is dry, and the refin iffues out of the pores of the ciftus, the peafants ftrike all the parts of thefe trees with a kind of whip, made with feveral thongs of leather, fixed to the end of a ftaff. The juice adheres to the leather, and is cleared off with a knife. This is pure labdanum, and is very rare. That which is known by the name of labda-- - num in tortis, is mixed with a very fijie ferruginous fand, for the purpofe of increasing its weight. 9. Dragon's blood is a refin of a deep red In the mafs, but brighter when in powder. It has neither tafte nor fmell. It is obtained from the drakena, in the Canary iflands, from which it flows in tears during the dog-days. It is alfo obtained from the petro-carpus draco. The parts are expofed to the va- pour of hot-water ; the juice iffues out in drops, which are col- feaed and wrapped up in the leaves of reeds. The dragon's blood of the Shops, which has the form of flat- tened orbicular loaves, is a compofition of various gums, to which this form is given, after they have been coloured with a Small quantity of dragon's blood. Dragon's blood is foluble in alcohol : the folution is red : the refin itSelS may be precipitated oS the Same colour. This refin is uSed in medicine as an aftringent. ARTICLE IV, Concerning Balfams. Some authors define balfams to be fluid inflammable fubftan- ces ; but there are Some which are dry. Others again give this name to the moft fragrant among the refins. M. Bucquet has confined this denomination to fuch refins only as have a Sweet flavour, capable of being communicated to water ; and which more efpecially contain fragrant acid and concrete falts, which may be feparated by decoaion or Sublimation. It appears therefore that thefe fubftances contain a principle not found in refins, which, combining with oxigene, forms an acid ; while the oil, faturated with the fame air, forms the refin. This acid Varieties of Benzoin. 445 fait is foluble in water and alcohol. As the chemical analyfis points out a fufficiently Striking difference between balfams and refins, we think it proper to treat them feparately. The fubftajices called Balfams are therefore refins united with a concrete acidJjalt. We are acquainted with three principal kinds ; viz. benzoin, the balfam of Tolu, and the ftorax cal- amita. i. Benzoin is a coagulated juice, of a pleafant Sragrant Smell, which becomes Stronger by Sriaion and heat. Two varieties oS this fubftance are known ; the benzoe amyg- daloides, and the common benzoin. The firft is eompoSed of the moft beautiSul tears of this balSam, conneaed together by a gluten oS the Same nature, but browner, and of the afpea of nutmegs in its Sraaure. The Second is merely the juice itSelf, without any mixture oS theSe fine and very pure tears. It comes to us Srom the kingdom oS Siam, and the ifland of Sumatra ; but we do not know the tree that affords it.* Benzoin laid upon hot coals, fuSes, Speedily, takes fire, and e- mits a ftrong aromatick Smell. But if it be merely heated, with- out Setting it on fire, it fwells up, and emits a more pleafant though lefs powerful fmell. Benzoin pounded, and boiled in water, affords an acid fait, which cryftallizes in long needles by cooling. This fait may alfo be extraaed by fublimation. It rifes by a degree of heat even lefs than that which is required to raife the oil of benzoin ; and this is the fubftance calfed Flowers of Benzoin, or the Sub- limed acid of Benzoin. Neither of thefe proceffes are econom- ical ; and in the preparation of thefe articles, in the large way, I begin by diftilling the benzoin, and caufe all the produas to pafs confounded together into a capacious receiver. I then boil the produa in water, and by this means I obtain a much greater quantity of the fait of benzoin : becaufe, in this ftate, the water attacks and diflblves the whole contents ; whereas the moft accurate trituration will not produce the fame effea. The fublimed acid of benzoin has a very penetrating aromat- ick fmell, which excites coughing ; more efpecially if the fub- liming veffels be opened while yet hot. It reddens the fyr- up of violets, and effervefces with the alkaline carbonates. It unites with earths, alkalis, and metals, and forms benzoates, of which Bergmann and Scheele have given us fome account. Alcohol diffolves benzoin totally, without leaving any refidue but fuch foreign impurities as the balf.im may happen to con- * For a drawing and deScription of uiis tree, co nf-lt Dryander, in the Flii!. Tranf. vol. lxxvii.No. ?r. 44<* Balfam of Tolu. Storax or Styrax. tain. It may be precipitated by the addition of water ; and then cowftifutes the opaque fluid called Lac Virginale. Benzoin is ufed as an aromatick in medicine ; but it is fel- dom ufed in fubftance, becauSe of its Sparing folubrtty : its tinc- ture, and volatile acid are uSed. The latter is aifgood incifive medicine to be adminiftered in pituitous obftruaions of the lungs, the kidneys, &c. It is given in extraas, or diffolved in water. Benzoin is employed in fumigations for indolent tumours. The oil is likewife an excellent refolvent. It is applied by fric- tion to members affiled with cold rheumatick and paralytick diforders. 2. The balfam of Tolu, of Peru, or of Carthagena, hasa mild and pleafant fmell. It is met with in commerce in two different forms ; either in ftdls or in the fluid ftate. The coco is foftencd in boiling water, and the balfam flows out in the fluid form. The tree winch affords it, is the Toluifera of Linrrceus. It grows in Somh America, in the diftria called Tolu, between* Garthagena and Nombre de Dios. The fluid balfam affords much volatile oil when diftilled by the heat oS boiling water. An acid Salt may be extraaed Srom tins balSam, which great- ly refembles that of'benzoin ; and may be obtained by the Same proceffes; but this Sublimed Salt is commonly brown,becauSe it is- SOrled by a portion of the balSam, which rifes with a lefs heat than benzoin does. This balfam is foluble in alcohol, and may be precipitated by the addition of water. It is much ufed in medicine, as an aromatick, vulnerary, and antioutvefcent remedy. It is adminiftered either triturated with Sugar, or mixed with fome extraa. A fyrup is prepared from it by diverting it in a gentle heat with Sugar; or by diflolvingit in alcohol, adding Sugar, and Suffering the alcohol to diffipate fpontaneoufly. It :s falfiried by macerating the diftilled oil of benzoin upon the buds of the balm-fcented poplar, and adding a fmall quanti- ty of the natural balfam. Storax or llyrax calamita is a juice of a very ftrong but plea- fant fmell. Two varieties are known in commerce : the one in reddifih clean tears ; the other in maffes of a blackifh red col- our, foft and fattv. . The plant which affords it is called the oriental liquid am- ber. It has been long fuppofed to be the ftyrax folio mail co- tonsi C. B. which is known in Piover^, in the wood of Li Balfams. Gum Refins. 447 Chafreufe de Montrieu, by the name of Alibouffer ; and, ac- cording to Duhamel, affords a very odorant juice, which he took for Storax. Its habitudes during analyfis are the fame as.the preceding and it exhibits the fame phenomena. It was formerly brought to us in canes or reeds, whence,us name of Storax calamita. Thefe three balfams form the bafe of thofe fragrant paftils which are burned in the chambers of the fick, to conceal or dif- guiSe bed Smells. TheSe balSams are made into maffes by means of gum; with the addition of charcoal arid the .nitrate of pot- afli, to facilitate combuftion. • ARTICLE V. Concerning Gum Refins. The gum refins are a natural mixture of extraa and refin. They feldom flow naturally from plants, but iflue out from in- cifions made for that purpofe. They are Sometimes white, as in the tithymalus and the fig-tree ; fometimes yellow, as in the chelidonium : fo that we may confider thefe fubftances as true emulfions, whofe conftituent principles vary in their propor- tions. The gum refins are partly foluble in water, and partly in alcohol. One charaaer of gum refins is, that they render water turbid in which they are boiled. This clafs is fufficiently numerous : but we ffiall only treat of the principal fpecies, and more efpecially thofe which are ufed in medicine. I. 01ibanum,or frankincenfe, is a gum refin, in tears of a yeilowifh white colour and transparent. Two kinds are known in trade : the male incenSe, in Small very pure tears; and the fe- male incenSe, in large and impure tears. The tree which affords it is not known. Some authors Sup- poSe it to be the cedar with cypreSs leaves. Olibanutn contains three parts oS refinous matter, and one of extraa. When it is boiled in water, the folution is white and turbid, like that of all the juices of this clafs. When it is frefh, it affords a quantity of volatile oil. Olibanum is ufed in medicine as a refolvent. But its chief ufe is in our temples, where it has been adopted as one of the inftruments of v.orffiip of the Divinity. It i-. ufed in hofpitals, to difguife the fmell of the putrid air which u exhaled. M- Achard has proved. that this proceeding ■44$ Scammeny. Gum Gut tee. has no other effea than that of deceiving the fenfe of fnielf. ing. 2. Scammony is of a blackiffi grey colour, a bitter and acrid tafte, and a ftrong naufeous fmell. Two varieties are met with in commerce ; one of which comes from Aleppo, and the Other from Smyrna. The firft is paler, lighter, and more pure ; the fecond is black, heavy, and mixed with foreign fubftances. It is extraaed from the convulvulus fcammonia, principally from the root. For this purpofe incifions are made at the head of the root: it is colfeaed in mufcle fhells. But moft of that met with in trade is obtained from fhe roots by expreflion. From the refults of the analyfis of Geoffroy and Cartheufer, it appears that the proportion of the component parts varies in the different fpecimens examined. The latter obtained near one half oS extract:, whereas the Sormer only one Sixth. Scammofiy is uSed in medicine as a purgative, in the dofe of feveral grains. When triturated with fugar and almonds, it forms a very agreeable purgative emulfion. When Softened by a mixture of the juice of liquorice, or of wild quinces, it forms the diagredium. 3. Gum guttse has a reddiffi yellow colour: it has no fmell, but its tafte is acrid and cauftick. Gum guttse was brought to Clufius in 1630. It comes from the kingdom of Siam, from China, and from the ifland of Ceylon, in cylinders of various Sizes. The tree which affords it is called Coddam Pulli. Her- man reports, from his own observation as an eye witnefs, that a milky and yeilowifh juice flows from incifions made in thefe trees; that this juice becomes thick by the heat of the fun ; and that, when it is in a ftate fit to be handled, it is formed into large globular maffes. Geoffroy has extraaed five fixths of refin Srom gum guttae. CartheuSer has afcribed to it more extraaive than refmous mat- ter. Gum guttse is Sometimes ufed as a purgative, in a doSe oS a Sew grains. But the principal uSe of this Substance is in paint- ing, where it is recommended by the beauty oS its colour. 4. Affa fcetlda is met with in tears of a yeilowifh white col- our ; but moft commonly in the form of loaves formed by the aggregation of a number of the tears. It has an acrid and bit- ter tafte, and its fmell is one of the moft difagreeable. The plant which it affords is called Ferula Affa Fcetida. This plant grows in Perfia : and the juice of its root is ob- tained by expreflion, according to Kaempfer. It is fluid and white when it iffues from the plant, and it emits an abominable Elaftick Gum. 44J fmell when recent. This juice lofes its Smell, and becomes col- oured, as it dries. But it ftill preServes fmell enough to entitla it to the name of Stercus Diaboli. The Indians find its flavour agreeable ; they uSe it for feafon- ing, and call it the food oftthegods : a proof which evinces, be- yond every argument, that taftes muft not be diSputed. Cartheufer found it to contain one third of refin. It is a folvent and difcutient remedy ; and more particularly Valuable as a moft powerSul antihyfterick. 5. Aloes is a juice of a red brown colour, and very confider- able bitternefs. Three fpecies are diftinguiflied—the foccotrine aloes, the hepatick aloes, and the coballine aloes ; they differ only in their degree of purity. M. de Juffieu, who faw thefe three varieties prepared at Morvicdro in Spain, affures us that they are all obtained Srom the aloe vulgaris. The firft va- riety is obtained by making incifions in the leaves. Time is allowed Sor its impurities to Subfide perfectly. The fluid is jhen decanted from the dregs, and left to become thick : after which it is put into leathern facks for fale, under the name of Soccotrine aloes. A juice of the fame nature is obtained by expreflion from the fame leaves, which, when clarified in the fame manner, forms the hepatick aloes : and the coballine aloes is obtained by a ftronger preffure. The Soccotrine aloes contains no more than one eighth of refin, according to Boulduck. The hepatick aloes contains half its weight. Aloes is very much ufed in medicine as a purgative, tonick, alterative, and vermifuge. 6. Gum ammoniack is fometimes met with in fmall tears, white within, and yellow without. But they are often united in the mafs, refembling the benzoe arnygdaloides. Its fmell is fetid; and its tafte acrid, bitter, and rather naufeous* This juice comes from the defarts of Africa, and the plant which affords it is unknown : it is prefumed to be of the clafs of umbelliferous plants, from the figure of the feeds Sound in it. Gum ammoniack is very much ufed in medicine. It is a very good alterative; and is given in pills, incorporated with Sugar, or in Some extraa. It may even be diflblved or diffufed in wa- ter ; this liquid becomes turbid, and of a yeilowifh white. Gum ammoniack enters into the compofition of all difcuffive plafters. . Concerning Caoutchouck, or Elaftick Gum. Elaftick Gum is one of thofe fubftances which it is difficult to clafs. It burns like refins; but its foftnefs, its elafticity, and its infolubility in the menftruums which ufually diflblve refins, do not allow us to clafs it among thoSe bodies. 3-1 4S» Elaftick Gum, The tree which affords it is known by the name of Seringa by the Indians of Para. The inhabitants of the province of Ef- meraldas, a province of Quito, call it Hhava ; and thofe of the province of Mainas, Caoutchouck. Mr. Richard has proved that this tree is of the family of the euphorbia ; and Mr. Dorthes has obferved, that the coccus which are covered with a down that refembles Small Straws, were cov- ered with a gum very much reSembling the elaftick gum. TheSe inSeas feed on the euphorbium; but thofe which come Srom other Situations afford the feme juice. We are indebted to Mr. Condamlne for an account, and ac- curate details, concerning this tree. (Acad, des Sciences 1751.) This academician informs us, after ' M. Frefuau, engineer at Cayenne, that the caoutchouck is a very lofty tree. Incifions are made in the bark ; and the white juice, which flows out in a more or lefs liquid ftate, is received in a veffel placed for that purpofe. This is applied in fucceffive coatings upon a mould of • clay, and dried by the fire, or in the fun. All forts of defigr* are traced upon it while foft ; and, when it is dry, the clay mould is crufhed, and the pieces fhaken out. This gum is very elaftick, and capable of great extenfion. When elaftick gum is expoSed to the fire, it becomes foft, fwells up, and burns with a white flame. It is uSed for illumi- nation inftead of candles at Cayenne. It is not at all foluble either in water or alcohol. But Mac- quer has affured us that ether is its true folvent; and upon this property he has instituted the art of making bougies for chirur- gical ufes of elaftick gum, by applying this folution upon a mould of wax till it is of the requifite thicknefs. Mr. Bernaird, to whom we are indebted for important obfer- vations upon this fubftance, found only the nitrick ether to dif- folve elaftick gum. Very pure fulphurick ether did not per- ceptibly aa upon it. If elaftick gum be put in contaa with a volatile oil, fuch as that of turpentine, or even if it be expofed to the vapour of that fluid, it fwells, foftens, and becomes very pafty. It may then be fpread upon paper, or applied as a varniffi to cloth ; but this covering preferves its adhefive quality, and does not lofe it for a long time. The mixture of volatile oil and alcohol forms a better folverit than the pure oil, and the varniffi dries more Speedily. Mr. Bernaird has concluded from his experiments that the elaftick gum is a fat oil, coloured by a matter foluble in alcohol, and foiled by the fmoke to which the gum is expoSed in drying, If linfeed oil be rendered very drying by digesting it upon the oxides of lead, and it be afterwards applied with a fmall bruffi Vnttn'of'the Ch'mefe. 451 upon any furface, and dried by the fun or in the fmoke, it af- fords a pellicle of a confiderable degree of firmneSs, evidently transparent, burning like the elaftick gum, arid wonderfully elaftick and extensible. IS this very drying oil be leSt in a wide {hallow veffel, the SurSace becomes thick, and Sorms a membrane which has the greateft analogy with the elaftick'gum. A. pound of this oil Spread upon a'ftone, and expoSed to the air for fix or feven months, acquired almoft all the properties of elaftick gum. It was ufed to make catheters and bougies; was applied to varniffi balloons, &c. Some gum refins are cleared by art of their extraaive princi- ple for the purpofe of applying them to various ufes. Such is the intention of the procefs ufed to make bird-lime. This is made from different fubftances, as the berries of mifletoe, the fruit of the febeften, Sec. But the beft is made of the hollyoak. Thefe trees are peeled in the month of June or July : the outer bark is rejeaed, and the fecond is boiled in fpring water for feven or eight hours. It is then made into molaffes, which are buried in the ground, and covered with ftones, for feveral layers one over the other. ASter having previoufly drained off the moifture, they are Suffered to ferment for fifteen days, until the matter has acquired the adhefive confiftence of pafte. The mafs is then beaten till it becomes capable of being wrought with the hands, or kneaded; after which it is waffied in a run- ning ftream. Laftly, it is placed for three or four days in another veflel, that it may throw up its fkum or impurities ; in which la*ft ftate it is put into proper veffels, and kept for ufe. The following compofition is likewife made ufe of under the name of bird-lime. Take one pound of bird-lime, one pound of goofe-greafe ; add to this one ounce of vinegar, half an ounce of oil, and the fame quantity of turpentine. Boil the mixture for feveral minutes, and heat the mafs when you are defirous of ufing it as a cement. It may be prevented from freezing in winter, by adding a fmall quantity of petroleum. Concerning Varnifh. The Pere dTncarville has informed us that the tree which af- fords the Varniffi of China is called Pfi-chou by the ChineSe. This tree is propagated by off-Sets. When the cultivator is de- firous of planting this, he takes a branch, which he wraps up in a mafs of earth, by means of flax. Care is taken to moiften this earth ; the branch puffies out roots, and is then pruned and transplanted, This tree grows to the Size of a man's leg. 4J1 Art of Varnijhing. This varniffi is drawn in fpring. If it be a cultivated tree, it affords three gatherings. It is extraaed by incifions made in the Spring ; and when the varniffi which is received in Shells does jiot flow, feveral hog's briftles, moistened with water or fpittle are introduced into the wound, and caufe it to run. When the tree is exhaufted, the uppej part of it is wrapped in Straw, which is fet on fire, and caufes the varniffi to precipitate to the bottom of the tree, where it flows out of perforations made for that purpofe. Thofe who coll»a the varniffi fet out before day-break, and place their Shells beneath the apertures. The Shells are not left longer than three hours in their place, becaufe the heat of the fun would evaporate the varniffi. The varniffi emits a Smell which the workmen are very care- ful to avoid reSpiring. It produces an effea which they call the bud of the varniffi. When the varniffi iffues Srom the tree, it reSemhles pitch. By expoSure to the air it naturally becomes coloured, and is at laft of a beautiful black. The juice which flows from incifions made in the trunk and branches of the thus toxicodendron, poffeffes the fame proper- ties. The tree that grows in our climates affords a white mil- ky fluid, which becomes black and thick by the contaa of the air ; its colour is the moft beautiful black : and it would be eafy to introduce this valuable fpecies of induftry into the kingdom, becaufe the tree grows wonderfullv well in all climates, and refills the cold oS the winter. To make the Varniffi bright, it is evaporated by the Sun ; and a body is given to it with hog's gall, and the Sulphate of iron, or martial vitriol. The Chinefe ufe the oil of tea, which they render drying by boiling it with orpiment, realgar, and arSenick. The varnifhes moft uSed in the arts have all oS them the refins for their baSe ; and the fundamental faas in this valuable art are reducible to the following principles. k To varnilh any fubftance, confifts in applying upon its fur- face a covering of fuch a nature, as fhall defend it from the in- fluence of the air, and give it a fhining appearance. A coat of varnifh ought therefore to poffefs the following properties :—i. It muft exclude the aaion of air ; becaufe wood and metals are varnifhed to defend them from decay and ruft : 2. It muft refift water ; for otherwife the effea of the varniffi could not be permanent. 3. It ought not to alter Such colours $9 are intended to be preServed by this means,. ArtofYarniJbing. Fecula. 45. j It Is neceffary therefore that a varniffi Should be eafily extend- ed or Spread over the SurSace, without leaving pores or cavities; that it ffiould not crack or Scale ; and that it ffiould refift water. Now refins are the only bodies that poffeSs theSe properties. Refins consequently muft be uSed as the bafes of varnifh. The queftion which of courSe preSents itfelf muft then be, how to dilpoSe them for this ufe ; and for this purpofe they muft be diffolved, as minutely divided as poffible, and combined in fuch a manner that the imperfeaions of thofe which might be difpo- fed to Scale, may be correaed by others. Refins may be diffolved by three agents—1. By fixed oil. 2. By volatile oil. 3. By alcohol. And, accordingly, we have three kinds of varniffi, the fat or oily varniffi, effential varniffi, and fpirit varniffi. Before a refin is diffolved in fixed oil, it is neceffary to render the oil drying. For this purpoSe the oil is boiled with metallick oxides ; in which operation the mucilage of the oil combines with the metal, while the oil itfelf unites with the oxigene of the oxide. To accelerate the drying of this varnifh, it is neceffary to add oil of turpentine. The effential varnifhes confift of a Solution of refin in oil of turpentine. The varniffi being applied, the effential oil flies off, and leaves the refin. This is ufed only Sor paintings. When refins are diffolved in alcohol, the varnifh dries very Speedily, and is fubjea to crack ; but this fault is correaed by adding a fmall quantity of turpentine to the mixture, which ren- ders it brighter, and lefs brittle when dry. The coloured refins or gums, Such as gum guttse, dragon's blood, &c. are uSed to colour varniffies. To give luftre to the varniffi after it is laid on, it is rubbed with pounded pumice ftone and water ; which being dried with a cloth, the work is aSterwards rubbed with an oiled rag and tripoli. The SurSace is laft oS all cleaned with SoSt linen cloths, cleared oS all greafineSs with powder of Starch, and rubbed # bright with the palm of the hand. ARTICLE VI. Concerning the Fecula. of Vegetables. The fecula appears to be only a flight alteration of mucilage \ for it differs Srom that Subftance' iu no other reSpea than in be- ing inSofeulc- in cold water, in which liquid it falls with wonder- fV qufekneL If \\ be put into hot water, it forms a mucilage, 454 Various kistds of Fecula. and-refumes all its charaaers. It feems that the fecula is fim- ply a mucilage deprived- of calorick. In faa a young plant is all mucilage; the old plants and fruits afford little fecula, be- caufe the heat is Stronger in young than in old plants, according to Dr. Hunter. There are few plants which do not conta!n fecula. Mr. Parmentier has given us a lift of all thofe which afford it, in his experiments. {See his Recherches fur les VegeteauxNourif- fans.) But the feeds of gramineous and leguminous vegetables, as well as the roots, which botanifts call Tuberofe, contain it taoft plentifully. Nothing more is required, in order to extraa the fecula, than to bruife or grind the plant In water; and the fecula which is at firft SuSpended in that fluid, foon falls to the bottom. We fliall not in this place attend to any other fecula but fuch as are wfed in the arts or in medicine. Such are tliofe of bryony, of potatoes, caffava, fago, falep, ftarch, &c. i. The fecula of bryony is extraaed from the root of that -plant. The bark is firft taken off from the root, which is then rafped, and Submitted to the prefs. The juice which flows out by expreflion is rendered white and opaque by a fecula which fubfides. The liquid is then decanted off, and the fecula dried. It is ftrongly purgative, on account of a portion of extraa which it retains j but it may be deprived of its purgative virtue by careful waShing ia water. If water be poured on the marc which remains beneath the preSs, a large quantity is obtained which is not purgative, becauSe the extraaive matter was forced out by the firft operation. Mr. Baume has propoSed to Substi- tute this fecula inftead of ftarch. The fecula is afforded by fimilar treatment of the roots of corn-flag and arum. 2. That which is generally known by the name of potatoe flour, is nothing but the fecula of this root obtained by ordinary and eafy proceffes. The root being well waShed, it is pounded. or crufhed in Such a manner as perfeaiy to deftroy its texture. The pulp is then put into a Sieve, and water poured on it, which carries off the fecula, and depofites it at the bottom of the re- * ceiving veffel. The water, which is coloured by extraaive mat- ter, and part of the parenchyma that remains fufpended, is de- canted off, and the deposition is wafhed feveral times. The colour of the fecula grows whiter as it dries ; and when dry it is very white and fine. As this fecula has become an article of common ufe for fome time paft, feveral inftruments have been contrived which are more or lefs fuited to bruife the potatoes. Rafps have been propofed turning in cylinders, mills armed with points of iron, &c. Various kinds cf Fecula. 455 3. The caffava of the Americans is extraaed from the roots et the maniock. This plant contains an acrid and very danger- ous poifon, of which it muft be very carefully deprived. The Americans take the freffi root of maniock, which they peel, rafp, and inclofe in a bag or fack formed of ruffies, and of a very open texture. This bag is fufpended from a ftaff; and a very heavy veflel is fattened to its lower part, which draws the bag down, fo as in Some meafure to comprefs the root, at the fame time that it receives the juice as it flows out. The juice is a moft dreadful poifon. When the root is well cleared of the juice, it is put into the fame bags, and expofed to dry in the fmoke. The Sifted root is called Caffava. To convert it into food, it is Spread out on a hot brick, or plate of iron ; and when the furface which refts immediately on the brick is of a reddiffi brown colour, it Is turned, to bake the other fide j and in this ftate it Sorms what is called Caffava bread. The expreffed juice carries with it the fineft part of the fecula which quickly fubfides j and this Secula, known by the name o£ Mouchaffe, is ufed to make paflry. The poifonc.s extraa which moft of thefe roots that abound in fecula contain, ought cleared of every foreign principle. There are likewiSe coloured Seculse, Such as indigo, which we fhall treat of when we come to the article dying. The uSes of feculoe are very numerous. 1. They conftitute a very nouriffiing food, becaufe the nutri- tive virtue of gramineous vegetables refides in them. Thofe feeds which man Jhas appropriated for his food, contain much ; and thefe feculse form a very nouriffiing jelly with hot water. It may be feen, in the work of Mr. Parmentier, that this is truly the moft fuitable nourishment for man. Some of thefe are e- ven entirely devoted to this purpofe, fuch as the caffava. In the northern climates, the lichens form almoft the whole of the food of man, and fuch animals as are not carnivorous ; and thefe lichens, according to the experiments of the Academy of Stockholm, afford an excellent ftarch by Simple grinding. The rein-deer, the Stags, and the other fallow cattle of the north of Europe; fubfift on the lichen rangiferinus. The Ice- Vegetable Gluten. 4S7 landers obtairi a very delicate gruel with fecula of the lichen Ice- landicus. 2. Starch boiled in water, and coloured with a fmall quantity of azure, forms a pafte which is ufed to give brightnefs, firm- nefs, ftrength and an agreeable colour to linen. The feculse are alfo ufed to make hair powder; and this con- sumption, which is prodigious, might be fupplied by ftarch made from lefs valuable plants than the gramineous ; and, if this were done, the Objeas of luxury would not enter into competi- tion with our immediate wants. ARTICLE VII. Concerning the Vegetable Gluten. The glutinous principle, which on account of its properties refembling thofe of animal fubftances, has been called, the Veg- eto-Animal fubftance by fome chemifts, is more particularly ob- tained from gramineous vegetables. We are indebted to Bec- cari for the difcovery of this fubftance ; and the analyfis of far- inaceous fubftances has fince been enriched with various impor- tant faas. To make the analyfis of any farina, the methods employed are fuch as are fimple, and incapable of decompofing or alter- ing any of its conftituent parts. A pafte is formed with the flour and water ; and this is kneaded and wrought in the hands under water, till it no longer communicates any colour to that fluid. The fubftance which then remains in the hand is tena- cious, duct:ile, and very elaftick ; and becomes more and more adhefive, in proportion as the water which it had imbibed flies off by evaporation. In this fame operation the fecula falls to the bottom of the water ; while the extraaive matter remains 'in folution, and may be concentrated by evaporation of the fluid. # If the glutinoussmatter be Stretched out, and then let go. It returns by fpontaneous contraaion to its original form. If in be left fufpended, it becomes extended by its weight ; and forms a very thin tranfparent membrane, which exhibits a kind of net- work, refembling the texture of the membranes of animals. 'M. Beccari has ©bfcrved that the proportion of glutinous mat- ter varies prodigioufly in the feveral feeds of gramineous vege- tables. Thofe of wheat contain the lajgeft quantity ; but hs never found it in the garden SlufFor plants which are ufed by us for food. The ijuantity of glutinous matter alfo varies in the feme kind of grain, according to the nature of the foil which ha> fup; ( rted ir. Humid fituations afford fcarcely anv 3...K '' 45'8 Vegetable'Gluteh. The glutinous matter emits a very charaaerifticfc aritrrial fmell. Its t^fte is infipid ; it Swells up upon hot coals ; becoiriss fotfA and perfeaiy dry in a dry air, or by a gentle heat ; in which ftate it refembles glue, and breaks Short like that fubftance. if in this State it be placed upon burning coals, it curls up, is agi- tated, and burns like an animal fubftance. By diftillation it af- fords the carbonate of ammoniack. Frefh-made gluten, expofed to the air, re'adily putrefies ; and when it has retained a fmall quantity of ftarch, this laft paffes to the acia. fermentation, and retards the putrefaaion of the gluten : and in this way a ftate is produced refembling that of cheefe. Water does not attack the glutinous part. If it be boiled with this fluid, it lofes its extensibility and adhefive quality ; a circumftance fo much the more remarkable, as it was indebted to that fluid for the developement of thefe qualities ; for this principle exifted without cohefion in the flour ; and when it is deprived of water by drying, it alfo lofes its elasticity and gluti- nous quality. Alkalis diffolve it, by the affiftance of a boiling heat. The So- lution is turbid ; and depofites the gluten by the addition of acids, but deprived of its elafticity. The nitrick acid diffolves gluten with aaivity ; and this acid at firft emits the nitrogenous gas, as when treated with animal fubftances. This is followed by an emiffion of nitrous gas ; and the refidue, by evaporation, affods the oxalick acid in cryftals. The fulphurick and muriatick acids likewife diffolve it. M. Poulletier has obferved, that falts with bafe of ammoniack may be obtained from thefe combinations diffolved in water or alcohol, * and evaporated in the open air. If the gluten be diffolved in the vegetable acids feveral times repeatedly, and precipitated by alkalis, it is reflored to the ftate of fecula : and according to Macquer, if vinegar be diftilled by a gentle heat from this fubftance, it is reojjced to the ftate of mucilage. This fubftance therefore poffeffes a very decided animal char- aaer. It is to this gluten that wheat owes its property of mak- ing a good pafte with water, and the facility with which it rifes. Rouelle difcovered a glutinous fubftance analagous to the pref- ent in the green fecula of plants," which afforded ammoniack, and empyreumatick oil, by diftillation. The expreffed juice of the herbaceous plants likewife afforded it; fuch as that of bo- rage, hemlock, forrel, &c. The Gluten is fometimes deftroyed by the fermentation of flour ; by which change it is deprived of the wholefome quali- Fermentation of Bread. Sugar. 4^9 tics itbefore poffeffed,, and is incapable of rifing, and forming good bread. Terina, or flour, is therefore compofed of three principles— the amylaceous principle, or ftarch ; the faccharine principle ; and the animal or glutinous principle. Whenever therefore, by a fuitable divifion, thefe principles are mixed together, and the fermentation is affifted by the known methods, each of thefp principles being capable of a different kind of fermentation, pecomes depofed, in its own peculiar manner. The Saccharine principle undergoes the Spirituous fermentation : and the amyl- aceous is changed by the acid fermentation. The panary fer- rnentation may therefore be confidered as an union of thefe three different fgontaneous changes. But as Soon as the leading phe- nomena of the Serrnentation are well developed ; and the prin- ciples, ^lrej|d"y well mixed and affimilated, have by this means Suffered a change oS their reSpeaive natures ; the Serrnentation "s flopped by baking : and the bread is Sound to be much lighter in confequence of thefe preliminary operations. The art of making bread was not known at Rome until the year 585. The Roman armies, on their return from Macedo- nia ; brought Grecian bakers into Italy. Before this time the Romans prepared their flour in no other way than by making it into pap or foft pudding; for which reafon the Romans, ac- < cording to Pliny, were called eaters of Pap.* See Aubery. ARTICLE VIII. Concerning Sugar. Sugar is likewife a conftituent part of vegetables, exifling in considerable quantities 'n a number of plants. It is afforded by the maple, the birch, wheat and turkey corn. Margraff ob- tained it from the roots of beet, red beet, fkirret, parfnips, and dried grapes. The procefs of this chemift confifted in digefting thefe roots, rafped or finely divided, in alcohol. This fluid dif- folves the Sugar ; and leaves the extraaive matter untouched, which Sails to the bottom. In Canada the Inhabitants extraa Sugar from the maple (acer montanum candidum.) At the commencement of fpring they heap fnow in the evening at the foot of the tree, in which they previoufly make apertures for the paffage of the returning fap. * Pulte autem non pane, vixifie longo tempore Romanos manifeftum quonium inde et Pulmenraria hodieque dicuntur. Plin' Hift. Nut. ib xviii. cap. yiii, et xi.—The date is 580 ab urbe condica. T. 4 ° • Boiling and Refining of Sugar. Two hundred pounds of this juice afford by evaporation fifteen of a brownifh fugar. The quantity prepared annually amounts to fifteen thoufand weight. The Indians likewife extraa Sugar Srom the pith of the bamboo. But the fugar which is fo unlverSally ufed is afforded by the fugar cane (arunda SacchariSera) which is raiSed in our colonies, When this plant is ripe, it is cut down, and cruflied by paffing it between iron cylinders, placed perpendicularly, and moved bywater or animal ftrength. The juice which flows out by this ftrong preffure is received in a Shallow trough placed be- neath the cylinder. This juice is called vefou ,• and the cane, after having undergone this preffure, is called begaffe* The juice is more or leSs Saccharine, according to the nature of the foil on which the cane has grown, and the weather that has pre- dominated during its growth., It is aqueous when the foil or the weather has been humid ; and in contrary circumftances it is thick and glutinous. The juice of the cane is conveyed into boilers, where it is boiled with wood afhes and lime. It is fubjeaed to the fame operation in three feveral boilers, care being taken to remove the fkum as it rifes. In this ftate it is called Syrup ; and is a- gain boiled with lime and alum till it is fufficiently concentrated, when it is poured into a veflel called the Cooler. In this veffel it is agitated with wooden Stirrers, which break the cruft as it forms on the furface. It is afterwards poured into calks, to ac-. celerate its cooling j and, while it is ftill warm, it is conveyed into barrels Handing upright over a ciftern, and pierced through their bottom with feveral holes flopped with cane. The fyrup which is not condenfed filters through thefe canes into the cif- tern beneath; and leaves the fugar in the ftate called CoarSe Sugar, or Mufcovado. This Sugar is yellow and Sat, and is pu- rified in the iflands in the following manner :—The fyrup is boiled, and poured into conical earthen veflels, having a fmall perforation at the apex, which is kept clofed. Each cone, re- verfed on irs apex, i.s fupported in another earthen veflel. The fyrup is ftirred together, and then left to cryftal'ize. At the end of fifteen or Sixteen hours, the hole in the point of each tone is opened, that the impure fyrup may run out. The bafe of thefe fugar loaves is then tui.en out, and white pulverized fu- gar fubftituted in its ftead ; which heing well preffed down, the whole is covered with clay, moiftened with water. This water filters through the mafs, carrying the fyrup with it which was * Thefe are the names in the French Sugar colonics. I do not find the #prreipc:.d:i.g terms in any -± our w?iters. T, Habitudes of Sugar. 4 found to be deprived of the oil, which remains on the cotton. Spielmann, after Pott, pro- pofes to diftil it with the muriatick acid ; it then fublimes white aud pure. Bourdelin clears it of its oil by detonation with ni- * .'.c:de ;a ths ori£;n2l; doubtlefs by overfight. T. 5! a Volcanoes. tre. This fait is prepared in the large way at Koningfberg, where the Shavings and chips of amber are diftilled. The fuctinick acid has a penetrating tafte, and reddens the tinaure of turnfole. Twenty-four parts of cold water, and two of boiling water, diffolve one of this acid. If a faturated folution of this fait be evaporated, it cryftallizes in triangular priSms, whoSe points are truncated. Mr. de Morveau obServes that its affinities are barytes, lime, alkalis, magnefia, &c. The oil of amber has an agreeable fmell: it may be deprived of its colour by diftillation from white clay. Rouelle diftilled it with water. When mixed with ammoniack it forms a liquid foap, known by the name of Eau de Luce. To make eau de luce, I diffolve Punick wax in alcohol, with a fmall quantity of oil of amber; and on this I pour the pure volatile alkali. Alcohol attacks amber, and acquires a yellow colour. Hoff- mann prepares this tinaure by mixing the fpirit of wine with an alkali. The medical ufe of amber confifts in burning it, and receiv- ing the vapour on the difeafed part. Thefe vapours are Strength- ening, and remove obftruaions. The oil of amber is applied to the Same uSe. A Syrup of amber is made with the fpirit of amber and opium, which is uSed to advantage as a Sedative ano- dyne medicine. The fineft pieces of amber are ufed to make toys. Wallerius affirms that the moft tranfparent pieces may be ufed to make mirrors, prifms, &c It is faid that the king of Pruffia has a burning mirror* of amber one foot in diameter ; and that there is a column of amber in the cabinet of the Duke of Florence ten feet high, and of a very fine luftre. Concerning Volcanos. The combuftion of thofe enormous maffes of bitumen which are depofited in the bowels of the earth, produces volcanos. They owe their origin more efpecially to the ftrata of pyritous coal. The decompofition of water upon the pyrites determines the heat, and the produaion of a great quantity of hydrogen- ous gas, which exerts itfelf againft the furrounding obftacles, and at length breaks them. This effea is the chief caufe of earthquakes ; but when the concourfe of air facilitates the com- * So in the original ; but the matter as well as the properties of this fubftance put it out of doubt that it fhould be lens. T. Volcanick Phenomena. 513 bullion of the bitumen and the hydrogenous gas, the flame is feen to iffue out oSthe chimneys or vents which are made : and this occafions the fire of volcanos. ' There are many volcanos ftill in an aaive ftate on our globe, independent of thofe of Italy, which are the moft known. The abbe Chappe has defcribed three burning in Siberia. Anderfon and Von Troil have defcribed tliofe of Iceland. Afia and Afri- ca contain feveral: and we find the remains of thefe fires or volcanick produas in all parts of the globe. Naturalifts inform us that all the fouthem iflands have been volcanized ; and they are feen daily to be formed by the aaion of thefe Subterraneous fires. The traces of fire exift even im- mediately around us. The fingle province of Languedoc con- tains more extina volcanos than twenty years ago were known to exift through all Europe. The black colour of the ftones, their fpungy texture, the other produas of fire, and the identi- t ty of thefiTfubftances with thofe of the volcanos at prefent burning, are all in favour of the opinion that their origin was the fame.* * A volcano was announced and defcribed to be burping in Langfledoc, refpecYmg which it is neceiTiry to give fome elucid.itio.i. This pretended volcano is known by the nam; of the Phofphorus of Venejan. • Venejan is a village Situated at the distance of a quarter of a league from the high road between St. Efprit and Bagnols. From time immem- orial at the return of fpring, a fire was feen from the high road, which in- creafed during the Summer, was gradually extinguu'hed m autumn, and wasvifible only in the night. Several perSons had a: various times directed their courfe from the high road, in a right line towards Venejan, to verify the fac"Lup°n the Spot ; but the neceffity ol-defcendaig uito a deep valley • 'before they could arrive thither, occafioned them todole light or the hre ; and on their arrival at Venejan no appearance was Seen in the leafl: refembling the fire of a volcano. Mr. dc Genffane defcribes this phenomenon, and compares it to theflafhingofa ftrong aurora borealis : he even fays that the country is volcanick. Hift. Nat. du Languedoc, Diocefe de'Uzes.— At length, in the courfe of the laft four or five years, it was obferved that thefe fires were multiplied in the fpring; and that, inftead of one,, there were three. Certain Philofophers of Bagnols undertook the project of ex- amining this phenomenon, more clof-ly, and for this purpofe they repaired • to a Spot between the high road ana Tenejan armed with torches, Speaking trumpets, and every other implement, which they conceived to be necefiary for making their obfervations. At midnight, lour or five of the party were deputed and directed towards the lire,; and thofe who remained behind directed them conltantlv in their way by means of their Speaking trumpets. They at kit arrived ^ the village, where they found three croupes of women winding filk in the middle of the ftreet by the light ot afire made of hemp Stalks. All the volcanick phenomena then disap- peared, and die explanation of the obfervations made on this fubject be- came very-fimple. fn the Spring,; the fire wjj weak, becaufe it was fed with wood, which afforded heat and light ; during the fummer, hemp ftalks were burned, becaufe light only was wanted. At that time there were three fires, becaufe th; fair of Saint Efprit was uear at hand, at which 3...R 5*4 Volcanick Phenomena. When the decompofition of the pyrites is advanced, and the (j vapours and elaftick fluid can no longer be contained in the bow- els of the earth, thevground is ihaken, and exhibits the phenom- '' ena of earthquakes. Mephitick vapotlrs are multiplied on the ■ furface of the ground, and dreadful hollow noifes are heard. In Iceland, the rivers and fprings are fwallowed up ; a thick fmoke t' \ mixed with Sparks and lightning is then diSengaged from the crater ; and naturalifts have obServed that, when the Smoke of VeSuvius takes the Sorm of a pine, the eruption is near at hand. To thefe preludes, which Show the internal agitation to be great) and that obftacles oppofe the iffue of the volcanick matters, Succeeds an eruption of ftones and other produas, which the la- va drives before it : and laftly appears a river of lava, which. Slows out, and fpreads itfelf down the fides of the mountain. At this period the calm is reftored in the bowels of the earth, and the eruption continues without earthquakes. The violent # efforts of the included matter fometimes caufe the fides of the mountain to open ; and this is the caufe which has fucceffively formed the fmaller mountains which Surround volcanos. Mon- te nuovo which is a hundred and eighty feet high, and three thou- fand in breadth, was Sormed in a night. This crifis is Sometimes Succeeded by an eruption oS afhes, which darken the air. TheSe afhes are the laft reSult oS the al- teration oS the coals ; and the matter which Is firft thrown out . is that which the heat has halS vitrified. In the year 1767, the afhes oS VeSuvius were carried twenty leagues out to Sea, and the < ftreets of Naples were covered with them. The report of Dion, concerning the eruption of Vefuvius in the reign of Titus, where- in the afhes were carried into Africa, Egypt, and Syria) feems to be fabulous. Mr. de SauSTure obferves that the foil of Rome ■> is of this charaaer, and that the famous catacombs are all made in the volcanick afhes. It muft be admitted, however, that the force with which all thefe produas are thrown, is aftonifhing. In the year 1769, a ftone twelve feet high, and four in circumference, was thrown to the diftance of a quarter of a mile from the crater : and in the year 1771, Sir William Hamilton obferved ftones of an enor-' mous fize, which employed eleven Seconds in Sailing. The eruption oS volcanos is frequently aqueous : the water, which is confined, and favours the decompofition oS the pyrites * ri thev fold their filk, and which consequently put them under the necefli- V ty >>f expediting their work. As theSe obfervers announced their arrival .,, with much none, the country people drove them back by a Shower of ftones, which the Don Quixotes of natural hiftory might have taken for a volcanick eruption. Volcanick ProduBs. • r 15 is fometimes ftrongly thrown out. Sea Salt isffound among the ejeaed matter, and likewiSe Sal ammoniack. In the year 1630, a torrent oS boiling water, . mixed with lava, deftroyed Portici and Torre del Greco. Hamilton Saw boiling water ejeaed. The fprings oS boiling water in Iceland, and all the hot Springs which abound at the SurSace oSthe globe, owe their heat only to the decompofition oS pyrites. Some eruptions are of a muddy fubftance ; and thefe form the tufa, and the puzzolano. The eruption which buried Her- culaneum is of this kind. Hamilton found,; an antique head, whofe impreffion was well enough preferved to anfwer the pur- pofe of a mould. Herculaneum, at the leaft depth, is feventy feet under the furface of the ground, and often at one hundred and twenty. The puzzolano is of various colours. It is ufually reddifh j fometimes grey, white, or green ; it frequently confifts of pum- ice ftone in powder; but fometimes it is formed of calcined clay. One hundred parts of red puzzolano afforded Bergmann, filex 55, alumine 20, lime 5, iron 20. When the lava is once thrown out of the crater, it rolls in large rivers down the fide of the mountain to a certain diftance, which forms the currents of lava, the volcanick caufeways, &c. The furface of the lava cools, and forms a folid cruft, under which the liquid lava flows. After the eruption, this crufl {,,. fometimes remains, and forms hollow galleries, v/hich Meffrs. Hamilton and Ferber have vifited : it is in thefe hollow places that the fal ammoniack, the marine fait, and other fubftances Sublime. A lava may be turned out of its courfe by oppofing banks or dikes againft it: this was done in 1669, to lave Catan- ia ; and Sir William Hamilton propofed it to the king of Naples, to preferve Portici. The currents of lava fometimes remain feveral years in cool. ing. Sir William Hamilton obferved, in 1769, that the lava which flowed in 1766 was ftill Smoking in Some places. When the current oS lava is received by water its cooling is quicker; and the maSs oS lava Shrinks So as to become divided into thoSe columns which are called baSaites. _ The Samous Giants Cauleway is the moft aftonifliing effea of this kind which < we are acquainted with. It exhibits thirty thoufand columns [ in front, and is two leagues in length along the fea coaft. Thefe columns are between fifteen and fixteen inches in diame- ter, and from twenty-five to thirty feet long. The bafaltes are divided into columns of four, five, fix, and J' feven fides. The emperor VeSpafian made an entire llatue ;■ with fixteen children, out oS a fingle column of bafaltes, which r he dedicated to the Nile, in the temple of Peace. 5*6 Volcanick ProduBs. Bafaltes afforded Bergmann, per quintal, filex 56, alumine 15, lime 4, iron 25. Lava is Sometimes Swelled up and porous. The lighteft is called pumice-ftone. The Subftances thrown out by volcanos are not altered by fire. They ejea native Subftances, Such as quartz, cryftals oS ame- thyft, agate, gypSum, amianthus, Seld-Spar, mica, Shells, Schorl, &c. The fire of volcanos is feldom ftrong enough to vitrify the matters it throws out. We know only of the yellowllh capilla- ry and flexible glafs thrown out by the volcanos of the ifland of of Bourbon on the fourteenth of May 1766, (M. Commerfon,) and the lapis gallinaceus ejeaed by Hecla. Mr. Egolfrjoufon, who is employed by the Obfervatory at Copenhagen, has fettled in Iceland, where he ufes a mirror of a telefcope which he has made out of the black agate of Iceland. The flow operation of time decompofes lavas, and their re- mains are very proper for vegetation. The fertile ifland of Si- cily has been every where volcanizcd. I obferved feveral an- cient volcanos at prefent cultivated ; and the line which Sepa- rates the other earths from the volcanick earth, conftitutes the limit of vegetation. The ground over the ruins of Pompeia is highly cultivated. Sir William Hamilton confiders fubterrane- an fires as the great vehicle ufed by nature to extraa virgin earth out of the bowels of the globe, and repair the exhaufted furface. The decompofition Of lava is very flow. Strata of vegetable earth, and pure lava, are occafionally found apphed one over the other ; which denote eruptions made at diftanees of time very remote from each other, fince it requires nearly two thoufand years before lava receives the plough. An argument has been drawn from this phenomenon to prove the antiquity of the globe : but the filence of the moft ancient authors concerning the volcanos of our kingdom, of which we find fuch frequent traces, proves that thefe volcanos have been extinguished from time immemorial; a circumftance which carries their exiftence to a very dilr.«mt period. Befides this, feveral thoufand years of con- nected obfervations have not afforded any remarkable change in Vefuvius or E:na ; neverthelefs, thefe enormous mountains are ail volcanized, and consequently formed of ftrata applied one upon the other. The prodigy becomes much more ftriking, when we obServe that all the Surrounding country, to very great distances, has been thrown out of the bowelsof the earth. The height of Vefuvius above the level of the fea is three thou- fand fix hundred :md fifty-nine feet ; its circumference thirty four thouSand .'our hundred and forty.four. The height of Et- Petrified Vegetables. _ CI7 na is ten thoufand and thirty-fix feet; and its circumference one hundred and eighty thoufand. The various volcanick produas are applicable to feveral ufes. 1. The puzzolano is of" admirable ufe for building in the wa- ter : when mixed with lime, it fpeedily fixes itSelS, and water does not SoSten it, Sor it becomes continually harder and harder. I have proved that calcined ochres afford the Same advantage Sor this purpoSe ; they are made into balls, and baked in a pot- ter's furnace in the ufual manner. The experiments made at Sette, by the commiffary of the province, prove that they may be fubftituted with the greateft advantage, inftead of the puz- zolano of Italy. * ' 2. Lava is likewife fufceptible of vitrification ; and in this ftate it may be blown into opaque bottles of the greateft light- neSs, as I have done at Erepian and at Alais. The very hard la- va, mixed in equal parts in wood afhes and Soda, produced an excellent green glaSs. The bottles made of it were only half the weight of common bottles, and much ftronger; as was proved by my experiments, and thofe which Mr. Jolly de Fleu- ry, ordered to be made under his adminiftration. 3. Pumice ftone likewife has its ufes ; it is more efpecially ufed to polifh moft bodies which are fomewhat hard. It is em- ployed in the mafs or in powder, according to the intended pur- pofe. Sometimes, after levigation, it is mixed with water to render it Softer. CHAPTER III. Concerning the Decompofition of Vegetables in the Bowels of the Earth. HERBACEOUS plants, buried in the earth, are flowly decom- pofed; but the waters which filter through and penetrate them relax their texture. The falts are extraaed ; and they become converted into a ftratum of blackifh matter, in which the vege- table texture is' ftill difcernible. Thefe ftrata are Sometimes perceived in digging into the earth. But this alteration is infi- nitely more perceptible in wood itSelf, than in herbaceous plants. The ligneous body oS a tree buried under the ground becomes of a black colour, more friable, and breaks Short; the fradure is Shining ; and the whole mafs appears, in this ftate, to fortn an uniform fubftance, capable of the finell polifh. The wood thus changed is called Jet. In the environs of Monrpellier, near St. John de Cucule, Several cart loads oS trunks of trees have been dug up whofe form was perfeaiy preferved, but which were convert- rd into jet. In the works at Nifmes pieces of wood were found eiuiivly Converted into the ftate of jet. In the neighbourhood 51$ Combuftion of Vegetables. ofVachcry, in Gevaudan, a jet is found, in which the texture of the walnut tree is very difcernible. The texture of the beech is feen in the jet of Bofrup in Scania. In Gnelbre a foreft of pines has been difcovered buried beneath the Sand ; and at Beichlitz two ftrata oS coal are wrought, according to Mr. Jars, the one bituminous, and the other oS SoSfil wood. I preferve in the cabinet oS mineralogy of Languedoc, feveral pieces of wood whofe external part is in the ftate of jet, whne the inter- nal part ftill remains in the ligneous ftate ; So that the tranfition from the one to the other may be obServed. Jet is capable oS receiving the moft perfea polifli. It is made in toys, fuch as buttons, fnuff boxes, neck lace3, and other ornaments. It is wrought in Languedoc, near Saint Colombe, at the diftance of three leagues from Caftelnaudray. It is ground down, and cut into facets, by mills. Jet foftens in the fire, and burns with the emiffion of a fetid odouT. It affords an oil which is more or lefs black, but may be rendered colourlefs by" repeated distillations Srom the earth of Murviel. CHAPTER IV. Concerning the Action of Air and Heat upon Vegetables. WHEN the heat is applied to a vegetable expofed to the air, certain phenomena are produced, which depend on the com- bination of pure air with the inflammable principles of the plant; and this is combuftion. In order to produce a commencement, a heated body is ap- plied to the dry wood which is intended to be fet on fire. By this means the principles are volatilized in the fame order as we have pointed out in the preceding article. A fmoke is produc- ed, which is a.mixture of water, oil, volatile Salt-, and all the gafeous produas which reSult from the combination oS vital air with the Several principles oS the vegetable. The heat then in- creaSes by the combination oS the air itSelf, becaufe it paffes to the concrete ftate : and when this ^heat is carried to a certain point, the vegetable takes fire, and the combuftion proceeds un- til all th» inflammable principles are deftroyed. In this operation there is an abforption of vital air, and a pro- ducfion of heat and light. The combuftion will be ftronger in proportion as the inflammable principle is more abundant, as the aqueous principle is lefs abundant, as the wood is more re- finous, and as the air is purer and more condenfed. Vegetable Fibres. J»9 The difengagement of heat and light is more -considerable* ac- cordingly as the combination of vital air is ftronger in a given time. The refidues of combuftion confift of fubftances which are volatilized, and fixed Subftances ; the one forms the foot, the other the a flies. The Soot partly ariSes from fubftances imperfeaiy burned, decompofed only in part, which have efcaped the aaion of vital air. Hence it is that the Soot may be burned over again: aad hence likewiSe it is that, when the combuftion is very rapid and effeaual, there is no perceptible Smoke ; becauSe all the inflam- mable matter is then deftroyed, as in the cylinder lamps, violent fires, &c. The analyfis oS Soot exhibits an oil which may be extraaed by diftillation ; a refin which may be taken up by alcohol, auji which arifes either Srom the imperSea alteration of the refin of the vegetable, or the combination oS vital air with the volatile oil. It likewiSe affords an acid, which is oSten formed by the decompofition of mucus ; and it is this acid, of great utility in the arts, for which the Academy of Stockholm has defcribeda furnace proper for colfeaing it. Soot likewife affords volatile falts, fuch as the carbonate of ammoniack, and others. A flight portion of fibrous matter is likewife volatilized by the force of the fire, and we find it again in the foot. The fixed principle remaining after combuftion, forms the afhes. They contain Salts, earths, and metals, oS which we have already treated. The Salts are fixed alkalis, Sulphates, ni- trates, muriates, &c. ; the metals are iron, gold, manganeSe, &Cr, and the earths are alumine, lime, filex, and magnefia. CHAPTER V. Concerning the Action of Air and Water, which determine a Commence- ment of Formentation that Separates the Vegetable Juices from the Lig- neous Part, WHEN the decompofition of vegetables is facilitated by the alternate aaion of air and water, their organization becomes deftroyed; the conneaion between the various principles is broken ; the water carries away the juices; and leaves the fibrous Skeleton naked, fufficiently coherent, and fufficiently abundant in certain vegetables, to be extraaed in this way. Hemp i* prepared in this manner. The abbe Rozier attributes the ad- vantage of watering to the fermentation of the mucilaginous part. M. Prozet has proved that hemp contains an extraaive 520 Vegetable Fibres. and refinous part; and that the watering deftroys the former, and the fecond is detached almoft mechanically. It has been obferved that the addition of a fmall quantity of alkali favours this operation. ' Running water is preferable to Standing water; becauSe Stand- ing water keeps up and developes a ftronger Serrnentation, which attacks the ligneous part. It has been obferved that flax prepared in running'water is whiter and ftronger than that which is prepared in Handing water. The flagnant water has likewife the inconvenience of emitting an unpleafant Smejl, pernicious to the animal economy. The addition of alkali correas and pre- vents this effea. In the diocefe of Lodeve the young fhoots of the Spanifh genet are prepared by a very fimple procefs. It is fown on the high grounds, where it is left for three years ; at the end of which time the fprigs or young fhoots are cut, and formed into bun- dles, which are fold from twelve to fifteen fous each. The firft operation confifts in crufhing them with a beetle. The follow- ing day they are laid in a running ftream, with ftones upon them, to prevent their being wafhed away. In the evening they are taken out, and laid in a heap on the banks of the river, upon Straw or fern, covering them with the fame, and loading the heap with ftones : this operation they call mettre a couvert. Every evening they throw water on the heap. At the end of eight days they open the mafs, and find that the bark is eafily feparated from the wood. They take.the packets, one after the other, and beat and rub them ftrongly with a flat ftone, till the epidermis of the extremities is well cleared off, and the whole Stem becomes white. It is then hung to dry ; and the bark which was feparated from the ligneous fubftance, is carded and fpun, and made into very ufeful cloth. The peafants are ac- quainted with no other linen for cloths, facks, Shirts, Sec. Eve- ry one prepares his own, none being made Sor Sale. The genet, genifta juncea, has likewiSe the advantage oS af- fording a green food to cattle during the winter ; at the fame time that it fupports the earth by its roots, and prevents its be- ing carried down into the vallies. The bark of the mulberry tree may be treated in the fame manner. Olive de Serres has defcribed a good procefs for this purpofe. It is the fkeleton formed by the vegetable fibre only, and de- prived of all foreign matter, .which is ufed to make cloth ; it is the moft incorruptible principle of vegetation, and when this fibre, being converted into cloth, can no longer be ufed as Such, it is Subjeaed to extreme divifion, to convert it into paper. The operations for this purpofe are the following -.—The rags are Vegetable Fermentation. 521 cleaned, and laid in water to rot j after which they are torn by hooked peftles moved by water : the fecond peftles under which they are made to pafs, are not armed with hooks like the firft, but merely with round nails ; the third are of wood only. By this means the rags are converted into a pafte, which is attenu- ated ftill more by boiling. This pafte is received in wire moulds, dried, and forms blotting paper. Writing paper is dip- ped in fize, and fometimes glazed. CHAPTER VI. C oncerning the Action of Air, of Heat, and of Water, upon Vegeta- bles. WHEN the various juices of vegetables are diffufed in water, and the aaion of this fluid is favoured by the combined aaion of air and heat, a decompofition of thefe juices enfues. The oxigenous gas may be confidered as the firft agent of fermenta- tion : it is afforded either by the atmofphere, or by the water which is decompofed. It was from an obfervation of thefe faas that Becher thought himfelf authorized to confider fermentation as a kind of combuf- tion :—" Nam combuftio, feu calcinatio per fortem ignem, licet putrefaaionis fpecies, eidemque analoga fit—fermentatio ergo definitur, quod fit corporis denfioris rarefaaio, particularumque aerearum interpofitio, ex quo concluditur debere in aere fieri, nee nimium frigido nee nimium calido, ne partes raribiles expel- Iantur, in aperto tamen vafe, vel tantum vacuo ut partes rare- fieri queant; nam ftriaa clofura, et vafis impletio, fermentation- em totaliter impedit"—Becher, PhyS. Subft. S. i. 15, v. cap. 11, P-3*3- The conditions neceffary for the eftabliShment of fermenta- tion are—1. The contaa of pure air. 2. A certain degree o£ heat. 3. A quantity of water more or lefs confiderable, which produces a difference in the effeas. The phenomena which effentially accompany fermentation are—1. The produaion of heat. 2- The abforption of oxi- genous gas. Fermentation may be affifted—1. By increafing the mafs of fermentable matter. 2. By ufing a proper leaven. 1. By increafing the fermentable mafs, the principles on which the air muft aa are multiplied ; confequently the aaion of this element is facilitated ; more heat is therefore produced by the fixation of a greater quantity of air ; and confequently the fermentation is promoted by the two caufes which moft em- inently maintain it, heat and air. 3...T $22 Conditions for Spirituous Fermentation. 2. Two kinds of leaven may be diftinguifhed. I. Bodies eminently putrefeible, the addition of which haftens the fermen- tation. 2. ThoSe which already abound with oxigene, and which confequently afford a greater quantity of this principle of Ser- rnentation. This effea is produced by the inhabitants of the banks of the Rhyne, by throwing frefh meat into the vintage, to haften the fpirituous fermentation (Linne Amcenit, Acad. Differt. de Genefi Calculi) : and fo likewife the Chinefe throw excrements into a kind of beer, made of a decoaion of barley *nd oats. And on this account it is that the acids, the neutral falts, chalk, rancid oils, and the metallick calces* &c. haften Ser- rnentation. The produas of fermentation have caufed different fpecies to be diftinguifhed ; but this variety of effeas depends on the va- riety of principles in the vegetables. When the faccharine prin- ciple predominates, the refult of the fermentation is a fpirituous liquor ; when, on the contrary, the mucilage is moft abundant, the produa is acid ; if the gluten be one of the principles of the vegetable, there will be a produaion of ammoniack in the fermentation : fo that the fame fermentable mafs may undergo different alterations, which always depend on the nature and re- fpeaive properties of the conftituent principles, the Sufceptlbili- ty of change, &c. Thus a faccharine liquid, aSter having un- dergone the Spirituous fermentation, may be fubjeaed to the acid fermentation by the decompofition of the mucilage which had refilled the firft Serrnentation : but instil caSes the concourSe of air, water, and heat, is neceffary to develope fermentation. We fhall therefore confine ourfelves to the examination of thefe three agents—r. On the juices extraaed from vegetables, and diffufed in water, which conftitutes the fpirituous and acid fer- mentations ; 2. On the vegetable itSelS, which will lead us to> the formation of vegetable mould, ochres, &c. ARTICLE I. Concerning the Spirituous Fermentation and its Prod'ie nult is 'W.'red. and the time a."r.r*.'icr.. The fh'ud malhing afferds fmall fe-«r. V. 5*6 Spirituous Fermentation, and put into calks, where it continues to ferment, and throw* off a frothy fcum by the bung, which becomes four, and ferves as a ferment for future brewings under the name of Yeaft. The produa of all the fubftances is a liquor more or lefs col- oured, capable of affording ardent fpirits, by diftillation, of an aromatick and refinous fmell, a penetrating hot tafte, which ftimulates the aaion of the fibres. Wine is an excellent drink, and is alSo ufed as the vehicle of certain medicines. Suchare— 1. The emetick wine, which is prepared by digefting two pounds of good white wine on four ounces of the crocus metallorum. 2. Chalybeated wine, made by digefting one ounce of fteel filings in two pounds of white wine. 3. The wines in which plants are infufed ; fuch as wormwood, Sorrel, and the liquid laudanum of Sydenham, which is made by digefting Sor Several days two ounces of Sliced opium," one ounce of faffron, one dram of pounded cinnamon and of cloves, in one pound of Spanish wine. We fliall proceed to examine the conftituent principles of theSe Spirituous liquors by taking that oS grapes for an example. The moment the wine is in the calk, a kind of analyfis takes place, which is announced by the Separation oS Some oSits con- stituent principles; Such as the tartar which is depofited at the fides, and the lees which are precipitated to the bottom : So that there remain only the ardent Spirit and the colouring matter . diffuSed in a volume of liquid, which is more or leSs confider- able. 1. The colouring principle is oS a refinous nature, and is con- tained in the pellicle oS the grape ; and the fluid ir. not coloured until the wine is Sormed ; Sor until then there is nothing which " can diffolve it; and hence it is that white wine may be made of red grapes, when the juice oS the grape is expreffed, and the half thrown away. If wine be evaporated, the colouring principle remains in the refidue, and may be extraaed by Spirit of wine. Old wines lofe their colour, a pellicle being precipitated, which is either depofited on the fides of the bottles, or falls to the bottom. .If wine be expofed to the heat of the fun during the fummer, the colouring matter is detached in a pellicle, which falls to the bottom j when the veffel is opened, the dif- colouring is more Speedy, and it is effeaed^ in two or three days during the Summer. The wine thus deprived of its colour is not perceptibly weakened. 2. Wine is uSually decompoSed by diftillation ; and the firft produa of the operation is known by the name of Brandy. Diftillation of Ardent Spirit. C27 Btf% lies have been made fince the thirteenth century; and it- was in Languedoc where this commerce firft originated. Ar- nauld de Villeneuve appears to have been the author of this difcovery. The alembicks in which wine was diftilled confifted for a long time of a kind of boiler, furmounted with a long cyl- indrick neck, very narrow, and terminating in an hollow hemi- sphere, in which the vapours were condenSed. To this Small capital was adapted a narrow tube, to convey the fluid into the Serpentine or worm pipe. This diftiltatory apparatus has been Succeffively improved. The column has been considerably low- ered ; and the Stills generally adopted for the diftillation of wines in Languedoc are nearly of the following form. The body of the ftill is flat at bottom, and the fides rife perpendicularly to the height of twenty one inches. At this height the fides in- cline inwards, fo as to diminish the opening to twelve inches. This opening ends in a neck of feveral inches long, which re- ceives the bafis of a fmall covering called the head, which ap- proaches to the figure of an inverted cone. From the angle of the upper bafe of the capital, there iffues a fmall beak, intended to receive the vapours of brandy, and tranfmit them into the worm pipe to which it is adapted. This worm pipe has five or fix turns, and is placed in a tub, which is kept filled with cold water, to condenfe the vapours. The body of the Still is ufually Surrounded by the mafonry as high as the neck, and the bottom only is expofed to the immedi- ate aaion of the fire. An aSh-hole, which is too fmall, a fire- place large enough, and a chimney place oppofite the door of the fire-place, conftitute the furnaces in which thefe Stills are fixed. , The ftill is charged with between five and fix quintals of wine : the diftillation is made in eight or nine hours; and from fixty to Seventy.five pounds of pit-coal are confumed in each diftillation. Every judicious perfon muft be aware of the imperfeaion of this apparatus. Its principal faults are the following : i. The form of the body is fuch as to contain a column of wine of confiderable height and little breadth, which being aa« ed.on by the fire at its bafe, is burned at that part before the up- per part is heated. 2. The contraaion of the upper part renders the diftillation more difficult and Slow. In Sa£t, this inclined part being con- tinually Struck by the atr, condenfes the vapours, which inceS- fantly return into the boiler. It likewiSe oppoSes the free paf- fage of the vapours, and forms a kind of eolopile, as Mr Baume has obferved j So that the vapours, being compreffed at this nar- row neck, reacT on the wine, and oppofe its further afoent. 528 Diftillation of Ardent Spirit. 3. The capital is not conftruaed in a more advantageous manner. The upper part becomes of the fame temperature ai the vapours, which cannot therefore be condenfed, and, by their reaaion, either, fufoend or retard the diftillation. 4. In addition to this imperfea form of the apparatus, is joined the moft disadvantageous method of administering the fire. The afh-hole is every where much contraaed ; the fire- place is very large, and the door Shuts badly. In confequence of this, a current of air paffes between the combuftible matter and the bottom of the ftill, and the flame is driven into the chimney, without being turned to advantage. A violent fire is therefore required to heat the ftove only to a moderate degree, in this defective conftruaion. . Several other degrees of perfeaion have been fucceflively ob- tained in the manufaaories of Mr. Joubert : but I have judged it poflible to add ftill more to what was known, and the follow-. ing are the principles I fet out from. The whole art of diftillation is reduced to the two following principles:—1. The vapours ought to be difengaged, and raifed in the moft economical manner ; 2. And their coiidenfation ought to be as Speedy as poSfible. To anfwer the firft of thefe conditions, it is neceffary that the boiler Should prefent the largeft poSfible Surface to the fire, and that the heat Should be every where equally applied. 2. The fecond condition requires that the afcent of the vapours Should not be impeded, and that they fhould ftrike againft cold bodies, which Shall rapidly condenSe them. The Stills which I have conftruaed upon theSe principles are more broad than high ; the bottom is concave, in order that the fire maybe nearly at an equal diftance from all the points of its furface ; the fides are elevated perpendicularly in fuch a man- ner that the body exhibits the form of a portion of a cylinder ; and this body is covered with avail capital, furrojunded by its refrigeratory. This capital has a groove or channel, projeaing two inches at its lower part within : the fides have an inclina- tion of Sixty-five degrees ; becauSe I have afcertained that, at this degree, a drop of brandy will run along without falling again into the ftill. The beak of the capital is as high and as wide as the capital itfelf, and infenfibly diminishes till it comes to the worm-pipe itfelf. The.refrigeratory accompanies the beak, or neck, and has a cock at its further end, which fuffers the water to run out, while its place is fupplied by other cold : water, which inceffantly flows in from above. When the water of the refrigeratory begins to be warm, a'. cock is then opened, that it may efcape in proportion as it i* Diftillation of Ardent Spirit. 529 more plentifully fupplied from above. By this means the wa- ter is kept at an equal temperature, and the vapours which ftrike againft the fides of the head are condenfed, at the fame time that thofe which rife fuffer no obftacle, as they are fubjeaed to no contraaion of fpace. In this conftruction, the worm pipe may be almoft difpenfed with, becaufe the water in the worm tub does not become perceptibly heated. Thefe proceedings are very economical and advantageous for the quality of the brandy is better, and the quantity is larger. The diftillation of the wine is kept up until the produa is no longer inflammable. This brandy is put into calks, when it be- comes coloured by the extraaion of a refinous principle contain- ed in the wood. The wine of our climates affords one fifth or one fourth of brandy, of the proof ftrength of commerce. The diftillation of brandy by a more moderate heat affords a more volatile fluid, called Spirit of Wine, or Alcohol. To make common fpirit of wine, brandy is taken and diftilled on a wa- ter bath by diftillation.* This Spirit of wine may be purified and reaified by fubfequent distillations, and taking only the SirSt portions which come over. Alcohol is a very inflammable and very volatile Subflance. It appears to be formed by the intimate union of much hydrogene and carbone, according to the analyfis of Mr. Lavoifier. This fame chemift obtained eighteen ounces of water by burning one pound of alcohol. If well dephlegmated alcohol be digefted upon calcined pot-afh, and afterwards diftilled, a very fweet al- cohol is obtained, and a faponaceous extract which affords alco- hol, ammoniack, and an empyreumatick oil. In this experiment the formation of volatile alkali appears to arife from the combi- nation of the hydrogene of the alcohol with the nitrogene of the pot-afh. There are various methods ufed in the arts to judge of the degree of concentration of fpirit of wine. Gunpowder is put into a Spoon, and moiftened with Spirit of wine, which is fet on fire: if the powder takes fire, the fpirit is confidered to be * The ardent fpirit fold in London by the ftame of Spirit of "Wine, or Lamp Spii it, is made by the rectifiers of malt and melaffes fpirit in Lon- don, by diftillation of tJfce refidues of their compounded fpirits. It is pret- ty conftantly of the fpecifick gravity of o,&45 at |he temperature cf 60 l&hrenheit ; and may, by careful n-iaificatioa, brf-brought nearly up to o,8ao. Dry alkali deprives it of mo: e of its water. On the Subject of the Strength of fpiiits, confult l^'agdea in Phil. Tracf. vol. bxxxi. T. ♦ 3...U « 53» Formation of Ether. good ; but the contrary, if this effea does not take place. But this method is fallacious, becauSe the effea depends on the pro- portion in which the fpirit of wine is ufed ; a fmall quantity al- ways inflames the powder ; and a Strong doSe never produces; th.is effea, becauSe the water which remains Soaks into the pow- der, and defends it from the combuftion. The areometer of Mr. Baume is not to be depended on ; be- caufe, in the ufe of it, no account is kept of the temperature of ihe atmofphere, which, by changing the denfity of the fpirit of wine, is produaiveof a change in the refult as given by this in- strument. That of Mr. Bories is more accurate, becauSe the thermometer is adapted to it ; and is now ufed in commerce. Alcohol is the folvent of refins, and of moft aromatick Sub- ftances ; and confequently it forms the bafis of the art of the varnifher and of the perfumer. Spirit of wine combined with oxigene forms a liquor nearly. inSoluble in water, which is called ether. Ether has been formed with moft of the known acids. The moft ancient of all is the vitriolick or fulphurick ethef. To make this, a certain quantity of alcohol is put into a retort, arid an.equal weight of concentrated fulphurick acid is gradu- ally added. The mixture is Shaken and agitated, to prevent the retort from breaking by the partial effea of the. heat which arifes. The retort is then placed on a heated fand bath, a re- ceiver is adapted, and the mixture is heated to ebullition. Alco- hql firft paffes over •, foon after which, Streams of fluid appear in the neck of the retort, and within the receiver which denote the rifing of the ether. Its fmell is agreeable. Vapours of ful- phureous acid fucceed the ether ; and the receiver muft be ta- ken away the moment they appear. If the diftillation be contin- ued, fulphureous ether is obtained, and the oil which is called Etherial Oil, or the fweet oil of wine ; and that which remains in the retort is a mixture of undecompofed acid, fulphur and a matter refembling bitumens. We fee that in this operation the fulphurick acid is decom- pofed ; and that the oxigene by combining with the hydrogene and the carbone of the alcohol, has formed three ftates, which we alfo find in the diftillation of fome bitumens—i. A very vol- atile oil or ether. 2. Etherial oil. 3. Bitumen. If the fulphurick acid be digefted upon ether, it converts the \$hofe gradually into etherial oil. When the ether is mixed with fulphureous vapours, it muft be reaified by a gentle heat; a few drops of alkali being firft poured in, to combine with the acid. Formation of Ether, 531 Sulphurick ether maybe made very economically, by ufing a leaden ftill with a head of copper well tinned. In this way I prepare it by the quintal without any difficulty. Mr. Cadet "has propofed to pour on the refidue of the retort one third part of good alcohol, and to diftil it in the ufual Way. Ether is very light, very volatile, and of a pleafant fmell. It is fo eafily evaporated, that if a fine rag be fteeped in this liquor then wrapped round the ball of the thermometer, and the instru- ment be agitated in the air, the thermometer finks to the freez- ing point.* Ether eafily 'burns, and exhibits a blue flame. It is very Spar- ingly foluble'in wafer. Ether is an excellent antifpaSmodick. It mitigates pains • pf the colick as if by enchantment, as it does likewife external {Kilns. The celebrated Bucguet had accuftomed himSelf fo much to this drink, that he took two pints per day : a rare ex- ample of the jsower of habit on the constitution. The mixture of two ounces of fpirit of wine, two ounces of ether, and twelve drops of etherial oil, forms the anodyne li- quor of Hoffman. Meffrs. NaVier, Woulfe, Laplanche, Bouge, and others, have defcribed various proceffes for making nitrick ether, which are more or lefs eafily imitated. For my part, I take equal parts Of alcohol, and nitrick acid of commerce, of the ftrength of be- tween thirty and thirty-five degrees. I put the whole into a tu- bulated retort, which I fit to a furnace, and adapt two receivers one fucceeding the other. The firft Teceiver is immerSed in a veffel of water. The fecond is Surrounded by a wet cloth ; and a Siphon communicates Srom its tubulure to a veffel of water in which it is plunged. When the heat has penetrated the mix- ture much vapours are diSengaged, which are condenSed in ftriae, on the internal furfaces of the receivers, whofe external * Mr. Carvallo has defcribed, in the Philofophical Tranf. for 1781, a pleafing experiment of freezing water by means of ether. The ether is put into a vial fo as not completely to fill it; and in the neck of this vial is fitted by grinding, a tube whofe exteriour end is drawn out to a capilla- ry finenefs. Whenever the bottle thus flopped is inverted, the ether is urged out of the tube into a fine Stream, in confequence of the preffure ex- erted by the elaftick etherial vapour which occupies the fuperionr Space of the bottle. This ftream is dire&ed on the outlide of a linall glaSs tube containing water, which it Speedily cools down to the freezing point; at which inftant the water becomes Suddenly opaque, in confequence of the ic,y cryftallization. If a bended wire be previoufly immerftd in the water, it may afterwards be drawn out, and the ice along with it. T. 53 2 Formation of Ether. furface is kept conftantly cold. The ether which I obtain is ve- ry pure and very abundant.* ^. When the precaution of diftilling it properly is attended to, Tnis ether becomes nearly fimilar to the vitriolick. Meffrs. de Laffone and Cornette have obServed that it was more Sedative. The diftillation oS the muriatick acid with alcohol produces only a mixture oS thefe two liquors, which is called the Dulcifi- ed Muriatick Acid. BeSore the theory of ethers, and the Simple procefs of com- bining a furplus of oxigene with the muriatick acid, were known, methods were invented to procure the muriatick ether, but fub? Stances were always made ufe of in which the muriatick acid was oxigenated. In this manner it was that the baron de Bornes propofed the concentrated muriate of zinc, mixed and diftilled with alcohol; and that the Marquis de Courtanvaux diftilled the mixture of a pint of alcohol with two pounds and a half of the fuming muriate ot tin. The theory of the formation of ether has in our time led to Simpler proceffes. Mr. Pelletier introduces a mixture of eight ounces of man- ganefe, and a pound and a half of muriate of foda, in a large tubulated retort; twelve ounces of fulphurick acid, and eight ouncej of alcohol, are afterwards added. Diftillation is then proceeded on ; and ten ounces of a very etherial liquor are ob- tained, from which four ounces of good ether are afforded by diftillation and reaification. The very concentrated muriatick acid, diftilled from manga- nefe in the apparatus of Woulfe, affords more ether. It is even Sufficient, for this purpofe, to pafs the oxigenated muriatick acid through good alcohol to convert it into ether. This muriatick ether has the greateft analogy with the ful- phurick. It differs from it in two charaaers only—1. It emits, in burning, a fmell as penetrating as that of the fulphurick acid. 2. Its tafte is ftyptick, refembling that of alum. From thefe experiments it is evident that ether is merely a combination of alcohol with the oxigene of the acids made ufe » The ingenious author has forgotten to caution the inexperienced chem- ift againft the danger of mixing thefe two liquors. The nitrous acid must be V'-ry gradually added to the fpirit of wine, by fmall portions at a time. It is faid, and with reafon, to be of great importance, that the nitrous acid be added to the fpirit, and not the fpirit to the acid ; for, in this laft cafe, the mixture will, during the greateft part of the time of the operation ot combining the fluids conf.ft of a large portion of acid, with a lmaller por- tion of fpirit; whereas, where the contrary method is adopted, the pro- portion of fpirit will always be greater than that of the acid, until the t.-i? tju.uiuiy of acid is added. T. Purification of Tartar. 533 of. I have even obtained an etherial liquor by repeated distil- lations of good alcohol from the red oxide of mercury. The idea of Macquer, who confidered ether as fpirit of wine dephlegmated, or deprived of water, had little foundation ; for the diftillation of the fpirit of wine from the moft concentrat- ed or drieft alkali, never, affords any thing but fpirit of wine more or lefs dephlegmated. Concerning Tartar. Tartar is depofited on the fides of calks during fermentation : it forms a lining more or lefs thick, which is feraped off." Thi§ is called crude tartar, and is fold in Languedoc from ten to fif- teen livres the quintal. All wines do not afford the fame quantity of tartar. New-: man remarked that the Hungarian wines left only a thin Stra- tum ; that the wines of France afforded more ; and the Rhen- ifh wines afforded the pureft and the greateft quantity. Tartar is diftinguifhed, from its colour, into red or white : the firft is afforded by red wine. The pureft tartar exhibits an imperfeaiy cryftallized appear- ance : the form is the fame we have affigned to the acidulous t.mrite of pot-afh ; a.nd it is this quality which is called grained tartar (tartre grenu) in our refineries at Montpellier. The tafte of tartar is acid and vinous. One ounce of water, at the temperature of ten degrees above o of Reaumur, diffolves no more than i o grains : boiling water diffolves more, but it falls down in cryftals by cooling. Tartar is purified from an abundant extraaive principle by proceffes which are executed at Montpellier and at Venice. The following is the procefs ufed at Montpellier :—The tar- tar is diflblved in water, and Suffered to cryftallize by cooling. The cryftals are then boiled in another veffel, with the addition of five or fix pounds of the white argillaceous earth of Murveil tp each quintal of the Salt. ASter this boiling with the earth, a very white Salt is obtained by evaporation, which is known by, the name of Cream of Tartar, or acidulous tartrite of pot-afh. M. Defmaretz has informed us (Journal de Phyf. 1771) that the procefs ufed at Venice confifts—1. In drying the tartar in i.on boilers. 2. Pounding it, and diffolving it in hot water, which by cooling affords purer cryftals. 3. Rediffolving thefe cryftals in warer, and clarifying the folution by white of eggs and allies. The procefs of Montpellier is preferable to that of Venice. The addition of i\r~. afhes introduce^ a foreign fait, which alters, ;he purity of the product. 584 Acid xf Tartar obtained. The acidulous tartrite of potafh cryftalli*ze"s ill feWahedwl priSms cut off flantwife. This Salt is ufed by the dyers as a mordant: but its grfcateft consumption is in the north, where it is ufed at table as a fea- foner. Tartar appears to exift in the muft, and consequently in thfe grape itSelf. This has been afcertained by the experiments of De Rouelle and the marquis de Bullion. This fait exifts in many other vegetables. It is Sufficiently proved that tamariSck and Sumach contain it; and the fame is true of the barberry, of balm, carduus benediaus, reft-harxowt. Water-germander, and fage. The acidulous tartrite of pot-aSh may be decompofed by- means of fire, in the way of diftillation ; in which cafe the acid and the alkali are obtained feparately. This decomposition may alfo be affeaed by the fulphurick acid. The celebrated Scheele has defcribed a procefs of greater ac- curacy for obtaining the acid of cream of tartar. Two pounds of the cryftals are diffolved in water, into which chalk is thrown by degrees, till the liquid is faturated. A pre- cipitate is formed, which is a true tartrite of lime, is taftelefs, atid cracks between the teeth. This tartrite is put into a cucur- bit ; and nine ounces of fulphurick acid, with five ounces of water, are poured on it. After twelve hours digeftion with oc- casional ftirring, the tartareous acid is Set at liberty in the folu- tion, and may be cleared of the fulphate of lime by means of cold water. This tartareous acid affords cryftals by evaporation ; which when expofed to the fire, become black, and leave a Spongy coal behind. Treated in a retort, they afford an acid phlegm, and Some oil. The tafte of this acid is very Sharp. It combines with alkalis, with lime, with barytes, alumine, magnefia, &c. The combination of pot afh with this acid forms cream of tartar, when the acid is in excefs; which is capable oS entering. into combinations, and forming triple Salts. Such is the Salt of Seignette, or tartrite of foda, which cryftalizes in tetrahedral rhomboidal priSms. The aciduleus tartrite of potafh is very fparingly foluble in ^vater. Boiling water diffolves only one twenty-eighth part. The addition of borax has been propoSed to facilitate the Solu- tion j as likewiSe Sugar, which is lefs efficacious than Uorax, but makes a very agreeable and purgative lemonade with this £lt. affirmation\of Vinegar* 535 ARTICLE II. Concerning the Acid Fermentation. The mucilaginous principle is more efpecially the fubftance- on which the acid fermentation depends ; and when it has been deftroyed, in old and generous wines, they are no longer capable of alteration, without the addition of a gummy matter, as 1 find from my own experiments. It is not true, therefore to fay- that all Subftances which have paffed through the vinous. fer- mentation, are capable of paffing to. the ftate of vinegar ; fince this change depends on the mucilage, which may not in all cafes- be prefent. There.are, therefore, three caufes necefiary to produce the acid fermentation in fpirituous liquors. 1. The exiftence of mucilaginous matter, or muetlage. 2. A degree of 1 heat between eighteen and twenty-five degrees of Reaumur. 3. The preSence of oxigenous gas. ''The proceSs indicated by Boerhaave for making vinegar, is ftill the moft frequently rffed. It confifts in fixing two cafks in a warm room or place. Two falSe bottoms of baSket work are fixed at a certain diftance from the bottom, upon which the refafe of grapes and vine twigs are placed. One of thefe tuns is filled with wine, and the other only half filled. The fermen- tation begins in this laft ; and, when it is in full aaion, it is checked by filling the cafk up with wine out of the other. The fermentation then takes place in the laft mentioned cafk, that remained half filled ; and this is checked in the Same manner by pouring back the fame quantity of liquid out of the other ; and in this way the procefs is continued till the vinegar is made, which is uSually in about fifteen days...' When the fermentation developes itfelS, the liquid becomes heated and turbid ; a great number of filaments are feen in it; it emits a lively fmell ; and much air is abforbed, according to> the observation of the abbe Rozier. A large, quantity of lees is formed, which fubfides when the vinegar becomes clear. This lees is very analogous to the fi- brous matter. Vinegar is purified by diftillation. The firft portions which paSs over are weak ; but Soon afterwards the acetous acid ariSes, and is ftronger the later it comes over in the diftillation. The fluid is called Diftilled Vinegar \ and is thus cleared of. its col- ouring principle, and the lees, which is always mere or lefi> abundant. 53$ Radical Vinegar, or Acetick-Acid. Vinegar may likewife be concentrated by expofing it to thd froft. The Superabundant water freezes, and leaves the acid more condenSed. The preSence of fpirit of wine, mucilage, and air, are necef- fary to form vinegar. Scheele has made it by decompofing the nitrick acid upon Sugar and mucilage. I communicated to the academy at Paris (vol. 1786) an observation of ( fome curiofity refpeaing the formation of vinegar. Diftilled water, impreg- nated with vinous gasj affords vinegar : at the end of fome months, a depofition is made of a fubftance in flocks, which is analogous to the fibrous matters of vegetables. When the wa- ter contains fulphate of lime, an execrable hepatick odour is de. veloped, a depofition of fulphur is afforded, and all this is ow- ing only to the decompofition of this fulphurick acid. As in the above experiments I had placed the water above the vinous fluid in fermentation, to impregnate it in the carbon. ick acid, the alcohol which evaporates with the acid carried the mucilage with it ; and the effeas, I obferved, are referable to this fubftance. The acetous acid is capable of combining with a ftronger dofe of oxigene ; and then forms radical vinegar, or the acetick acid. To form the acetick acid, the metallick oxides are diffolved in the acetous acid ; the fait which is obtained being then ex- pofed to diftillation, affords the oxigenated acid. It has a very- lively Smell, is cauftick, and its aaion upon bodies is very dif- ferent from that of the acetous acid. This acetick acid has the advantage of forming ether with al- cohol. For this purpofe, equal parts of the acid and alcohol ' are to be diftilled together. The produa of the diftillation is to be again added to the refidue in. the retort; and a fmdi . quantity of the water of Rabel is likewife to be added. The ; whole becomes converted into ether. The combination of the acetous acid with pot-afh forms the acetite of pot-afh. To make this fait, pure pot-afh is faturated with diftilled vin- . egar, the liquor filtered, and evaporated to dryneSs in a glafs,.v veffel over a very gentle fire. The acetite of pot-afh has a pen- etrating acid tafte ; is decomposed by diftillation ; and affords an acid phlegm, an empyreumatick oil, ammoniack, and a large quantity of very odorant gas, formed of carbonick acid and hy- ..' drogene. The coal.contains much fixed alkali in a difengaged ftate. This Salt is very Soluble in water, and deliqueices in the air. .... PutrefaBion of Vegetables. 5«7 The fulphurick acid poured upon it, decompofes it ; and the produas which come over are fulphurick acid and acetick acid» , The acetous acid likewife combines with foda ; and this combination is improperly called Cryftallizable Terra Foliata. The acetite oS Soda cryftallizes in ftriated priSms, and does not attraa the humidity of the air. When thefe falts are diftilled, they leave a refidue, which forms an excellent and very aaive pyrophorous. The acetous acid likewiSe combines with ammoniack. The acetite which is produced is called the fpirit of MindereUs. This Salt cannot be evaporated without the lofs of a confiderable part on account of its volatility : but, by a long evaporation, it af- fords needle formed cryftals, of a hot and penetrating tafte, and attraaing moifture from the air. Lime, fixed alkalis, mere heat or fire, and the acids, decompofe this fait. The fulphate of pot-afh, fprinkled with the acetick acid, forms the fait of vinegar. ARTICLE ltt. Concerning the Putrid Fermentation. In order that vegetables may undergo the two fermentations we have treated of, it is neceffary that the juices fhould be ex- traaed, and prefented in a confiderable volume. A due degree of heat, together with other circumftances artificially brought together, are likewife neceffary ; for a grape, left on the ftalk, produces neither ardent fpirit nor vinegar, but rots. It is this new kind of alteration we Shall at prefent proceed to treat of. This fermentation is the moft natural termination Of the veg- etable. It is indeed the only end to which the natural courfe of things is direaed ; fince it is by this means that the exhaufted SurSace oS the globe is repaired. The two other Sermentations are the mere effeas of art, and form no part of the great plan of nature The life of the greateft part of vegetables lafts but a few months ; but the feeds they depofite affure their re-produaion» There are other more robuft vegetables which fupport the cold of winter, and only caft their leaves at that period. The annual vegetables, and vivacious plants, are altered by the combined ac- tion of the caufes we have mentioned : and the refult, accord- ing to the degree of decompofition, is either manure, vegetable earth, or ochre. The conditions of the vegetable fermentation are the follow^ ing- 3...W 5 3* fmfaSiiH df VegWdbles. r. It is ndctffraYy that the ctfgarii ration be impregnated with water. Dried vegetables are rfteferved" without putrifying ; and if they be moifte'n'ed, their fubfequent alteration is prodigioufly actdetated. In this manner it is that plants heaped together become heated, blacken, and take fire, if not fufficiently dried. Fires of this kind are not rar£, and the theory is not difficult to be explained'. Wetted topes, ntoift hay heaped together, and in a word every vegetable Subttance, putrefies or rots with great- er facility, the more perfeaiy its texture is impregnated with \vater. 2. The1 conta*a of ait is the fecond neceffary caufe in the pu- trefaaion of vegetables1. It is reported, in the Ephemerides of the Curious in Natural Phenomena, for 17^7, that ripe cherries were prefdfved for forty years, by indlofirig them in a veffel well luted, and placed at the bottom df a Well. 3. A certain degree of heat is likewiSe neceffary. The heat between five and ten degrees is fufficient to caufe decomrJofL tion. A greater heat dillipates the humidity, dries the vegeta- ble, and preferves it from putrefaaion. Too little heat retards or Sufpends it. 4. It is likewife fieceffsry for the due effea of this decomposi- tion, that the vegetables Should be heaped together, and their juices arftftirfant. A greater quantity of air is then combined with the ve^jetsftle; becaufe the juices and the furfaces are then more con* fideVable % and confequently a greater degree of heat is produv ce*d, which accelerates the decorhpofitiori. When vegetables are heaped together, and their texture is f&fteried by the Humidity With which they are impregnated, to- gether with their dwrt juices, the phenomena of decompofition arfe the following'; the colour of the vegetable is changed ; the gfeen leave's become yellow, the texture becomes lax, and the riafts lefs Coherent ; the Cotouf 6f the vegetable itfelf changer to biar.k or brown ; the rhafs rifes, and perceptibly fwells up jf the heat becomes more ihteflfe, and is perceived on approach- ing the heap j and the fumes which arife have already a fmell, vftiich Sometimes is not disagreeable ; at the fame time bubbles arifd, arid break at the Surface* of the liquid, whett the vegetables are* reduced tb a1 magma. This gas is a mixture of nitrogene hydrogene, and carbonick acid. At this epdcha, likewiSe ah ammbniacal gas is emitted, which is formed in thefe circum- stances : dnd, in proportion as theSe appearances diminish, the ftrohg and offensive odour is Succeeded by another which is fainter and milder, and the maSs becomes dry. The internal patt ftill exhibits the vegetable ftruaur*, when the Stem is folid and the fibrous matter has been the predominating principle j Vegetable Mould. 535* and it then constitutes manure or Soil. Hence it ariSes that the herbaceous plants of a looSe texture, and abounding in juices are not capable oSforming manure by their decompofition, but are reduced into a brown maSs of little confiftence, in which neither fibre nor texture are pbfejnted ; aud #$» is .what, for the moft part, Sorms vegetable mould. Vegetable mould uSually conftitutes the firft covering or Stra- tum of our globe ; and in jjuch cafes jEherein it is difcovered at a depth in the earth, there is no doubt but it has been buried by fome revolution. When a vegetable is cancelled into.earth by this tumultuous fermentation, it ftill retains the remains of the vegetable mixed and confounded with thejother folid. earths .and metallick pro- duas ; and by diftillation it affords oil, nitrqgene gas, and of- ten hydrogene. ' It may therefore be confidered as an inter- mediate fubftance between crude and organick bodies, which participates of the inertia of the one, apd the aaivity of the. o- ther ; and which in this ftate is ftill fubjea to an infenfible fer- mentation, that changes its nature ftill more, and deprives it of all its organick contents. Thefe remains pS vegetables Still con- tained in vegetable earth, Serve as food for pther plants that may grow in it. The infenfible progrefs oS Serrnentation, and the Suaion of vegetables, impoverish the vegetable earth, deprive it of all its organick matter and there remain only the earths and metallick refidue which form the Stiff poor foils and ochres when the ferruginous principle is very abundant. As this muddy earth is a mixture of all the primitive earths, and fome of the metals which are the produa'of vegetation, as well as the oils, the Salts, and other products we meet with in it; we may confider it as the refidue of the vegetable decompo- sition, as the great agent and means by which nature repairs the continual loffes the mineral kingdom undergoes. In this mix- ture of all the principles the materials of all compounds exift j and thefe materials are So much the more diSpoSed to enter into cpmbinations, as they are in a more divided or difengaged State. It is in theSe earths that we find diamonds, quartz-cryftals, Spars, gypSum, &c. It is in this martrix that the bog ores, or ochre- ous ores of iron, are formed ; and it appears that nature has re- served the impoverished refidue oS vegetables for the reproduc- tion or reparation^ the earthy and metallick fubftances of the globe, while the organick remains are made to ferve as nourish- ment for the growth of other Succeeding vegetables. PART THE FIFTH. CONCERNING ANIMAL SUBSTANCES INTRODUCTION. X HE abufe which, at the commencement of- this century, was made of the application of chemiftry to medicine, pccafioned, a Short time afterwards, that all the relations be- tween the Science and the art of healing were mistaken and rejeaed. It would no doubt have been more prudent, as well as more ufeful, to have conneaed thefe mistaken applications ; but chemiftry was not perhaps at that time in a Sufficiently ad- vanced Slate, to be advantageoufly applied to the phenomena of living bodies; and even at this day, we See that, though the^phy- fiology of the human body is enriched with various interefting faas, there is ftill much to be done before they will he fuffi- ciently numerous to exhibit a fatisfaaory maSs of dparine. The imperfea fucceSs of chemiftry in that branch of the fcience which has the ftudy of man for its pbjea, arifes from the very nature of the fubjea itfelf. Some chemifts, by consid- ering the human body as a lifelefs and paffive fubftance, have fuppofed the humours to undergo the fame changes as they would have been fubjea to out of the body ; others from a ve- ry fuperficial knowledge oS the constitution oS theSe humours, have pretended to explain all the phenomena of the animal econ- omy. All have miftaken or overlooked that principle of liSe, which inceffantly aas upon the Solids and fluids ; modifies, without ceafing, the impreffion of external objeas ; impedes the degenerations which depend on the constitution itfelf ; and pre- fents to us phenomena which chemiftry never could have known or prediaed by attending to the invariable laws obferved in in- animate bodies. None of the bodies pf the mineral kingdom are governed by an internal force. They are all Subjeaed to the direa aaion pf foreign fubftances, without any modification from any vital prin- ciple ; and the air, water and fire, produce in them the effeas which are neceffary, conflant, and fubjea to calculation; whence it happens that we a»e able to determine, modify, and Of Animal Bodies. {41 vary the aaion of thefe various agents at pleafure. It is not the Same with living bodies ; they are all indeed Subjea to the influ- ence of external bodies ; but the the effea of thefe is modified by the reaaion of the vital principle, and is varied according to the difpofition of that principle. The chemift cannot therefore determine the effeas a priori, and in a general way. He muft fearch for his refults rather in the living body itfelf than in the operations of his laboratory ; and can have no affiftance from his analyfis but in afcertaimng the nature of their component parts. But their aaion, effeas, or tranfpofitions, can only be known by a ferious Study of the funaions of the living body. Chemiftry can perform every, thing in the mineral kingdom, becaufe every thing depends on the laws of the affinities. But, in the kingdoms of organized beings, this fcience is fubordinate to the laws of the economy of living bodies ; and its refults can only be affirmed to be true, when they are confirmed by obfer- vation. The more the funaions of the individual are independent of organization, the lefs is the empire of chemiftry over them, be- caufe the effeas are modified in a thoufand ways ; and it is this which renders the application of chemical principles to the phenomena of the human body fo very difficult ; for the or- ganization is not only very complicated, but the effeas are con- tinually varied by the powerful influence of the mind. There is not however any funaion in the animal economy, upon which the fcience of chemiftry cannot throw fome light. If we confider them in the healthy ftate, we Shall perceive that eyery organ produces fome change in the humours it receives ; and though the chemift may indeed be ignorant of the manner in which Such changes are produced, it is by his art alone that the difference between the original fluid, and that which has been elaborated, can be afcertained. Befides which, the func- tions of the various organs are exercifed upon external objeas, and thefe objeas come under the confederation of chemiftry. We are at prefent, for example, acquainted with the nature of the air which ferves for refpiration, its effeas on the lungs, and its influence on the animal economy. We are even now able to determine whether any air be good or bad, and know how to correa tha.t which is vitiated, &c. We likewife poffefs fome accurate ideas of the nutritive principle oS certain Subftan- ces ; and chemiftry teaches us how to diSpoSe of the reSpeaive aliments, and adapt them to the various circumftances. The analyfis of waters is fufficiently perfect to admit of our distin- guishing the properties qf that fluid relative to health, and to fefea the b#ft for our own, ufe: fo tha$, while the principle of &4£ Qf A»imal Bodies. J*fe .ntpfides over and governs all the internal operations -of thje human body by a mechanifm which is very imperfectly known to Ms, we.fee neverthelefs that all the funaions receive an impreffion more or lefs direa from external objeas j, that all the materials jftfed for the fupport of the machine are Supplied from without,; rthat principle of life which colfeas and diSpoSes of the materials, .after laws unknown to us, is capable neither of choofingnpr rejc&- ing them jand that the funaions would be very fpeedily altered^, ifchemiftry, founded on obfervation, were not careful to remove .the noxious, and felea fuch bodies as are of advantage to the fyftem- Chemiftry therefore can do nothing in the arrange- ment of the materials, hut poffeffes unlimited power in their fe- feaion and preparation. When the organization is deranged, this defea of order can ^rife.only from external or internal caufes. In the firft cafe, the analyfis .of the air, the water and the food, will afford accurate notions Sufficient to re-eftablifh the Sunaions. In the Secoacj -the chemical examination of the humours may afford informa- tion fufficient to direa .tbe phyfician in pointing out the moft fuitable remedy. Sometimes the humours are decompofed in the body, as in vitro. We obferve all the phenomena of a de- jgeneration and complete difunion oS the principles which com- pofe the blood, in the Scurvy, cachexy, malignant fevers, Szc. It feems as iS, in Such caSes, the vital principle abandoned the government, and leSt the Solids and fluids to the deftruaive ac- tion of external agents ; in confequence of which they become ^ecornppSed in the fame maner as they ufually do when Separat- ed ftpm. the body. When tbe principle of animality is once extmguifbcad, the ,fame cauSes which maintained the Sunaions, and whpSe effeas .were modified by that principle of life, now aa with their • whole energy on the body, and decompofe it, Cbeonuftrj has difcovered methods of extraaing from thefe dead bodies a vari- ety of fubftances of ufe in the arts and in pharmacy. Chemiftry is therefore applicable to the animal economy in the ftate of health,and in the ftate of GckneSs. The chemical art has marked the limits between .vegetable '• .and animal Subftances. TheSe laft afford ammoniack by putre- faaion, while the fermentation of the former developes ardent fpirit. The latter leave a coal which purns eafily .; whUcthe .former become converted into a coal almqft incombustible. An- .imal matters contain much nitrogene, which may be diSengaged by.means oS nitrick acid. The interesting Memoirs of Mefi*. ..Berthollet and De Fourcroy on animal fubftances, anay.be cjpn- fulted to great advantage, Digeftion. Gaftrick Fluid. ft($ CHAPTER I. Concerning Digeftion. -THAT humour which is known by the name of the Gaftrick Juice, is feparated by glands placed between the membranes which line the ftomach ; and; from theSe it is emitted into the ftomach itfelf. In Order to obtain the gaftrick juice in a ftate of purity, the arlirnais rnterftfed to furnrfh it are kept fafting for two days" after which the Stomach is extraaed. frt this manner Spallanzarri obtained thirty Seven Ounces oS this juice out of the two firft Stomaehrof a Sheep. The fame naturalift caufed animals to* ftpalfow thin tubes of metal, pierced with feveral holes, into which he had put Small Sponges, very clean and dry. He cauf- ed crows to fwallow eight at a time, which were vomited up at the end of three hours and a half. The juice which he obtain- ed was yellow, transparent, Salt, bitter, and leaving very little Sediment, when the bird was falling. The gaftrick juice may likewife be procured by the vomiting which is excited by irri- tation during fafting. M. Scopoli has obferved that the moft fluid part only is thrown up by irritation; and that the thicker part does not quit the ftomach but by the affiftance of an emet- ick. M. Gaffe, who had long accuftomed himfelf to Swallow the air, which anfwered the purpofe of an emetick with him, has availed himfelf oS this habit to make fome experiments with the gaftrick juice. He SuSpends his reSpiration, receives air into his mouth, and pufhes it towards the pharinx with his tongue. This ah, rarefied in his ftomach, produces a convulfive motion, Which clears it of its contents'. Spallanzani has obferved that eagles fpontaneoufly emit a confiderable quantity of gaftrick juice, when fafting in the morning. We are indebted to Reaumur and the abbe Spallanzani for very interefting experiments refpeaing the virtue and effeas of the gaftrick juice in digeftion. They caufed animals to fwallow tubes of metajl, perforated in various places, and filled with ali- ments', to examine their effeas. The philofopher of Pavia uv Sed purfes oS thread, and bags of linen and of woollen. He himSelf Swallowed fmall purfes filled with flefh boiled or raw, with bread mafticated, and alSo in its original ftate, &c. and likewife Small cylinders of wood, five lines in length and three in diameter, pierced with holes, and covered with cloth. M. Goffe, availing himfelf Of the facility with which he wa9 able to vomit by means of the air, has taken all kinds of food 544 TheGafln.-kJmc*. and examined the changes they had undergone, by returning them at intervals more or lefs remote Srom the time of deglutition. From theSe various experiments it Sollows—i. That the gaf- trick juice reduces the aliments into an uniform magma, even out of the body, and in vitro ; and that it aas in the Same man- ner on the ftorr.urh after de«;th : which proves that its effea is chemical, ai,d aimolt independent of vitality. 2. That the gaf- trick juice effects the Solution 01 the aliments included in tubes of metal, and confequently deSended Srom any trituration. 3. That though there is no trituration in membraneous Stom- achs, this action powerfully affifts the effea of the digeftive juices in animals whoSe ftomach is muScular, Such as ducks, geefe, pigeons, &c. Some of theSe animals bred up with Suffi- cient care that they might not Swallow ftones, have nevertheless broken Spheres and tubes of metal, blunted lancets, and rounded pieces of glafs, which were introduced into their Stomachs. M- Spallanzani has ascertained that SleSh included in Spheres Suf- ficiently ftrong to refift the muScular aaion, was completely di- gefted. 4. That the gaftrick juice aas by its Solvent power, and not as a ferment; becauSe the ordinary and natural digef- tion is attended with no difengagement of air, nor inflation, nor heat, nor in a word, with any of the phenomena of fer- mentation. M-Scopoli obServes very well that nothing pofitive or certain can be afferted reSpeaing the nature of the gaftrick juice. It is fometimes acid and Sometimes infipid. M. Brugnatelli has found in the gaftrick juice oS carnivorous birds, and Some others, a dif- cngaged acid, a refin, and an animal fubftance, united with a fmall quantity of common fait. The gaftrick juice of ruminat- nating animals contains ammoniack, an extraaive animal fubftance and common fait. In our time the phofphorick faftts have been found difengaged in the gaftrick juice. It appears, from the obfervations of Meffrs. Spallanzani and Goffe, that the nature of the gaftrick juice varies according to that of the aliments. This juice is conftantly acid when the di- et is vegetable. The abbe Spallanzani affirms, contrary to Meffrs. Brugnatelli and Carminati, that birds of prey have never afforded him an acid juice ; and he affirms the fame of ferpents, frogs, fifties, &c. In order to Shew clearly that there is a great difference be- tween tbe gaftrick juices of various animals, it is fufficient to ob- ferve that the gaftrick juice of the kite, the falcon, &c. does not diffolve bread, though it digefts flefh meat; and that the gaftrick juice of the turkey, the duck, &c. has no aaion upon flefh, but converts the h#rdeft grain into a pulp. Properties of Milk. 54- Meffrs. Jurine, Toggia, and Carminati, have made the moft SucccSsful applications of the gaftrick juice in the treatment of wounds. CHAPTER II. Concerning Milk. OF all the animal humours, milk is beyond conrradiaion the leaft animalized. It appears to partake of the nature of chyle ; it preferves the qualities and charaaer of the aJiments ; and for this reafon we are induced to place it at the head of the hu- mours of animal bodies. Milk is feparated in organs called breafts or udders ; and though the clafs of animals with breafts exhibits the greateft analogy in the internal conftruaion of thefe organs, yet the milk varies in the feveral fpecies. In the human fpecies it is more faccharine ; in the cow, milder or fofter : the milk of the goat, and of the afs, are flightly aftringent; and it is for this reafon that they are ordered to be taken in diforders which have weak- ened and exhaufted the human frame.* Milk is the firft food of young animals. Their weak and fee- ble Stomachs are incapahle of digefting and affimilating aliments afforded by the earth ; and nature has accordingly provided them a food more animalized, and confequently more anala- gous to their ftruaure, until their increaSed ftrength permits them to uSe a coarSer Sood. Hunter has obServed that all the animals which diSgorge to feed their young, have glands in the ftomach, which are Sormed during the incubation, and afterwards gradually obliterated. Milk is in general of an opaque white colour, and faccharine tafte. * It Seems moft probable that the pre-eminence ftill given to the milk of the afs, arifes from no better rtafon than the loud and Sonorous voice of the animal which, by a kind of reaibritpg very common among the an- cient phyficians, has led to a couclufion that the milk of iuch a creature muflbe good for the lungs. The root fatyrion, the milk of the goat, and niany.QJther Subftances, formerly flood high in medical estimation, for rea- fons equally obvious and equally Superficial. It muft not however be de- nied but that, when the poSTeffor of an exhaufted constitution becomes ;So far obedient to advice as regularly to take anes milk,, and attend to other circumftances of regimen, he may find himfelf benefited ; and the a fie 3 milk, merely as milk, fubftit'-ted irfktd of fome leis friendly beverage or food, mav be srntuJ^u to a fhare in"the general effect. T. 3...X 546 Acid of Milk, By attending to the various alterations it undergoes when left to itfelf, or when decomposed by chemical agents, we m~/ af£ rive at a perfc& knowledge of its nature. . > Milk expofed to the air is decompofed in a longer or Shv. r?f time, according to the degree of heat of the atmoSphere. Zu if the temperature of the atmofphere be hot, and the mi'1;, 3.1 large quantity, -it may pafs to the fpirituous fermenra-pn. Marco PoUvfhc Venetian who wrote in the thirteenth ce.uury, affirms that the Tartars drink mares milk, fo well prepared that it might be taken for white wine. Claude Strahelenberg re- ports that the Tartars extraa a vinous fpirit from milk, which they call Arki (Defcription de I'Empire de Ruffie.) Joha( George Gmelin, in his Voyage to Siberia, affirms that the milk is Suffered to become four,,and is afterwards diSIfifled, M. Nicolas OferetlkowSky, of St. Peterfburgh, has.proyecU-- r. That milk deprived of its cream cannot produce ardent fpirit, either with a ferment or without- 2. That milk agitated in a clofe veffel affords ardent Spirit. 3. That fermented milk lofes its Spirituous principle by heat, and paffes to jth$ State of vinegar. Journal de Phyf. 1770. Milk •becomes; four in the- fummer, and in three or four days the acidJhas acquired its ftrength. . If the whey be then filtered, and evaporated to half, cheefe is depofited. IS it be ag^in fifter- od, and a Small quantity of the tartareous acid be added, a quan- tity of Small crystals of tartar are Seen to be formed »n the courSej. of an hour aSterwards, which according to Scheele can (not) ariSe only from the Small quantity of muriate potafh (in raiUc, but from an .effential Salt*) which milk alwajs contains. To feparate the various principles contained in four whey, the following procefs may he ufed, which was pointed out by the celebrated Scheele. Evaporate the four milk to one eighth. All the acid feparates, and remains on the filtre. Pour limp water on the refidue ; an earth is precipitated, and the lime combines with the acid. The lime may be difplaced by the oxalick acid, which forms with it an infoluble oxalite, which falls down* and the acid ojf milk remains difengaged. The fluid is then to be evaporated to the confiftence of honey, and upon this very pure alcohol if to be pouted*. ;f he fugar. 0/ milk, and all the other, principlef, are infoluble, except the acid. The mafs being then filtered, * The words in the parenthefes are added, to render the text conforrn- able to Scheele's Effay. T. ■■■;■■ Sugar of Milk. 547 the acid of milk may be feparated from its folvent by diftillation. This is the acid known by the name of Laaick Acid. It pof- feffes the following characters. i. When faturated with potafh, it affords a deliquefcent fait, foluble in alcohol. 2. With foda, a fait not cryftallizable, and foluble in alcohol. 3. With ammoniack, a deliquefcent fait, which Suffers moft of its alkali to eScape beSore the heat has deftroyed the acid. 4. Barytes, lime, and alumine, form with it Salts which are delique cent. 5. Magnefia affords fmall cryftals, which are refolved into a liquor. 6. BiSmuth, Cobalt, anrimotty, tin, mercury, filver, and gold, are not attacked by either hot or cold. 7. It diflblvCs iron and zinc, and produces hydrogenous gas. The Solution of iron is brown, and does not afford cryftals : that of zinc cryftallizes. &. "With copper it affumes a blue colour, which changes to greeft, and afterwards to an obfeure brown, without cryftallizing. 9. When kept in digeftion upon lead for Several days it dif- folves it. The folution does not afford cryftals. A light fedi- ment of a white colour is formed, which Scheele confiders as a fulphate of lead. Whey not four contains a faline fubftance, known by the name of Sugar of Milk. Meffrs. Valgamoz'and Lichtenftein have de. Scribed the procefs uSed to obtain this faline fubftance. The milk is deprived of its cream in the uSual manner, and of its curd by runtiet. It is then concentrated by evaporation till it has acquired the confiftence oS honey, aSter which it is put into moulds, and dried in the Sun. This is called Sugar oS Milk in Cakes (fucre de lait en tablettes) Thefe cakes are diffolved in water, clarified with white of egg, evaporated to the confiftence of Syrup, and Set to crystallize in a cool place. It affords white cryftals in rhomboidal parallelopipedons. Sugar of milk has a flightly Saccharine tafte, infipid, and as it were earthy. It is Soluble in three or four pints' of hot wa- ter. Mr. Rouelle obtained from twenty-four to thirty grains of afhes from one pound oS this Salt burned. Three fourths con- Sifted oS muriate of potafh, and the reft was carbonate of po:- }v neutral cryftallizable fait, foluble in eight times its weight of boiling wa- ter and Separable for the moft part by cooling. 7. With mineral alka'i it forms a fait which lequires oniv five parts of boiling water for its folution. g With volatile alkali it forms a fait which, after being gently dried, has r -;/v, tafte 0 It does not perceptibly act on the metals ; but forms, tSi their calces, falts of very difficult folubility, which therefore Wl down. T« Coagulation of Milk. 549 monly made ufe oS. For this purpoSe the mirk is warmed,»and twelve or fifteen grains of rennet is added to each pint. Gal- lium, the flowers oS thiftle or artichokes, and the internal mem- brane of the ftomach of birds dried, and reduced to powder, Stc. are among the fubftances which may be uSed to turn milk. The whey obtained in this manner is turbid , but may be clari- fied by boiling it with white of egg, and fubfequent filtration. On the mountain of Larzac I have feen the dairy woman plunge her arms up to the elbows in the milk, and change their place from time to time. This was done with a view to haften the feparation of the principles ; and it is probable that the hea», and'perhaps certain emanations from the arm itfelf, might favour that effea. The folid mafs which feparates from whey, contains two other fubftances very interefting to be known; namely cheefe and butter. • ' If any vegetable or mineral acid be put into milk, a coagula- tion follows as is well known. The only difference is, that the mineral acid affords lefs cheefe or curd than the vegetable ; and the various fubftances ufed to coagulate milk, may perhaps aa merely by virtue of the acid the y contain. Olaus Borrichius obtained no acid from curdled milk at a degree of heat incapable of decompofing it. The coagulum which is afforded in all thefe cafes, contains a fubftance of the nature of gluten, which forms the cheefe ; and another fubftance of the nature of oils, which forms the butter. When cheefe is prepared for the table, the butter is not feparated, becaufe it renders it milder and more agreeable. The cauftick alkalis diffolve cheefe by the affiftance of heat. But it is not held in folution by an alkali in milk. . If one part of cheefe newly feparated, and not dried, be mix- ed with eight parts of water flightly acidulated by a mineral acid, and the mixture be boiled, the cheefe will be diffolved, though it would not have been fenfibly acted on by a vegetable acid. This is the caufe why the vegetable acids feparate a much great- er quantity of curd from the fame quantity of milk than the mineral acids do. The caufe why falts, gums, fugar, &c coagulate milk, may be deduced from the greater affinity of the water with thefe bodies than with the cheefe. The earth of cheefe is a phofphate of lime, according to Scheele. No fubftance has a ftronger refemblance to cheefe than the white of ego; boiled. White of egg is diffolved in diluted acid, and al'o in cauftick alkali, and in lime water, and is precipitated from them by acids. 55° C&eefi. Butter, Soheele thinks that the coagulation of white of-egfc, lymph, and cheeSe, is owing to the combination of calorick ; and he proves his opinion as follows : Mix one part of white of egg with four parts of water *, pour in a fmall quantity of pure al- kali ; add as much muriatick acid as is neceffary to faturate it, and the white of egg will coagulate. In this experiment there is a change of principles. The heat of the alkali combiner with the white of egg, and the alkali with the muriatick acid.* Ammoniack diffolves cheefe more effeaually than ficed alka- lis. If a few drops be poured into coagulated milk, it quickly caufes the the coagutum to disappear. Concentrated acids likewiSe diffolve it. Nitrick acid difenga- ges nitrogene. The curd dried, and placed in a proper fituation to under- go a commencement of the putrid fermentation, acquires confift- ence tafte and colour. In this ftate it is uSed at table by the name of Cheefe. At Roquefort, where I have attended the manipulations of the excellent cheeSe which is made there, care is taken to prefs the curd well, in order to expel the whey, and to dry it as accu- rately as poSfible. After this it is taken into caves, where the temperature is two or three degrees above o. The fermenta- tion is developed by a fmall quantity of Salt. The putrefaaion is fufpended by Scraping the furface from time to time ; and the fermentation thus governed by art, and kept under by the cool- nefs of the caves, produces a flow effea upon all the ciieefe, and fucceflively developes the red and blue colours, of which I have given the etiology in a Memoir on the Fabrication of Cheefe at Roquefort, prefented to the Royal Society of Agriculture, and printed in the fourth volume of the Annates Chimiques.^ Butter is the third principle contained in milk. It is feparat- ed from the fcum and the cafeous matter by rapid agitation. The Subftance called cream is a mixture of cheefe and butter * The reafoning oS Scheele is more fully this :—Heat coagulates white of egg, without diminifhing its weight: whence he concludes coagulated white of egg to be a combination of heat with white of egg. Acids expel heat from cauftick alkalis when they combine with them, but none from mild alkalis. A very dilute alkali is ufed in this experiment, that the tem- perature maynot be railed, a«d neverthelefs the effect takes place ; but it does not when a mild alkali is ufed. Whence he concludes that the heat oS the cauftick alkali, inftead of being employed to raife the temperaturfc, has entered into combination with the white of egg, and coagulated it. T \ It is in thefouith volume ol"theAnnates de Ch'fmie that/the author has iniertcd' an extract from this excellent Memoir ou this fubjecu T* Properties of the Blood. e 11 which floats on the top of the milk. Violent agitation converts this into froth; in which ftate it is called whipped cream. Butter has a foft confiftence, is of a yellow golden colour more or lefs deep, of a mild agreeable flavour, melts eafily, and becomes folid again by mere cooling. Batter is eafily changed, and becomes rancid like oils. The acid which is developed may be carried off by water, or by Spir- it of wine, which diffolve it. Fixed alkali diffolves butter, and forms a Soap little known. , ,. Diftillation affords a coloured concrete oil from butter, and a ftrong pungent acid. This oil, by repeated diftillation, becomes altered, and refembles volatile oils. Milk is therefore a mixture of oil, lymph, Serum, and fait. This mixture is weakly united, and the union between the prin- ciples is eafily deftroyed. Milk is Said to be turned when the diSunion of its principles is effeaed by mere repoSe ; but when this feparation is made by re-agents it is Said to be curdled* or coagulated. CHAPTER III. Concerning the Blood. BLOOD is that red humour which circulates in the human bo- dy by means qf thearteries.and veins, and Supports life by Sup- plying all the dtgans with the peculiar juices they demand. It is this humour which receives the produa of digeftion from the ftomach, which it elaborates and animalizes. This hu- mour is with reafon confidered as the Socus oS life. The differ- ence pf temperaments with regard to the paflions, his been at- tributed to it by all the philofophers who have treated this fub- jea. It is in vain that phyficians have changed their fyftem ; for the opinions of the people have been lefs verfatile, and they have continued to attribute all the Shades of temperament to the modifications of the blood. It is likewife to the alterations of this humour that phyficians have for a long time afcribed the caufe of almoft every malady. It is more efpecially entitled to the attention of the chemift. The blood varies in the fame individual, not only with regard to the ftate of health, but likewife at the fame inftant. The blood which circulates through the veins has not the fame in- * Lait tourne and lait caillf. This distinction fcarcely obtains in the Englifh language. T. 55 2 Properties of the Blood. tenfity of colour, nor the fame confiftence, as that of the the arteries; that which flows through the organs of the breafl differs from that which paffes languidly through the viSccra of the lower belly. The blood differs alSo—-i. According to the age. In infancy it is piler and lefs confiftent. 2. According to the tempera- ment., Sanguine perfons have the blood of a vermilion red ; in the phlegmatick it is paler -, and in the cholerick it is more yellow. The temperature of the blood is not the Same in the Several fpecies of animals. Some have the blood hotter, and fome colder than the medium in which they live. Animals with lungs have the blood redder and hotter than thofe which are without that organ ; and the colour and heat are in proportion to the extent and perfeaion of the lungs, as M. Buffon and Brouffonet have obServed. The blood putrefies by a gentle heat. If it be diftilled on the Water-bath, it affords the phlegm of a faint fmell, which eafily putrefies. Blood dried by a proper heat, effervefces with acids ; if expofed to the air, it attraas humidity ; and at the end of feveral months a faline efflorefcence is formed, which Rouelle has afcertained to be Soda. IS the diftillation of blood be carri- ed farther, the produa is acid, oil, carbonate of ammoniack, &c. A fpongy coal remains in the retort, of very difficult in- cineration, in which are found Sea Salt, carbonate of foda, iron, and phoSphate of lime. Alcohol and the acids coagulate the blood ', alkalis render it more fluid. But if the blood received in a Shallow baSon be obServed, the following alterations are feen :—It firft becomes divided into two very diftina Subftances, the one liquid, Slightly greenifh, and called lymph, or Serum ; and the other reddilh and Solid, called the fibrous part of the blood. It is this feparation of the blood which has caufed the exiftence of polypi in the larger vef- fels to be credited, becaufe concretions have been found in thofe veffels after death. We will feparately examine thefe two fub- ftances. Serum has a yellow colour, inclining to green. Its tafte is flightly faline. It contains a difengaged alkali, turns fyrup of violets green, and hardens in a moderateJieat, which is the char- aaer of the lymph. Serum diftilled on a water-bath affords an infipid phlegm, neither acid nor alkaline, but very readily pu- trefying. When this phlegm has paffed over, the refidue is tranfparent like horn, no longer foluble in water,«and affording by diftillation an alkaline phlegm, carbonate of ammoniack, an$ a fetid blackifh oil more or leSs thick •, the remaining coal in the Properties of the Blood. 553 retort is very voluminous, and very difficult to incinerate ; the .j.fhes afford muriate of foda and phofphate of lime. Serum eafily putrefies, and then affords much carbonate of ammoniack. Serum poured into boiling water coagulates >, but it contains a part which is foluble in water, to which it communicates a milky colour, and all the properties of milk, according to Boucquet. Alkalis render the ferum more fluid, but acids coagulate it. By filtering and evaporating the fluid, a neutral fait is obtained, confifting of the acid employed, and foda. It appears therefore that the lymph is kept in the liquid ftate by the predominating alkali. The thickened ferum affords mephitis by the nitrick acid, al*- fifled by a Slight heat; if the fire be increafed, nitrous gas is difengaged ; the refidue affords the oxalick acid, and a portion of malick acid. Serum is coagulated by alcohol j but the coagulum is foluble in water, and in this it differs much from the coagulum formed by acids : this difference depends on the circumftance that the alcohol feizes the water which diluted the ferum ; whereas the acid feizes the alkali which diffolved it. The clot or fibrous part of the blood likewife contains much lymph ; but this may be difengaged by waShing. The water at the fame time carries off the colouring matter, which con- tains much iron : and this coagulated part, when well wafhed, forms a fibrous white fubftance void of fmell ; which, diftilled on the water bath, affords an infipid phlegm, eafily SuSceptible of putrefaaion. The refidue becomes very dry, even by a gen- tle heat ; when fuddenly expofed to a confiderable heat, it Shrinks up like parchment ; but when diftilled in a retort it af- fords an alkaline phlegm, carbonate oS ammoniack, oil, &c. The coal, which is lefs voluminous and lighter than that of lymph, affords the phoSphate of lime by incineration. The fibrous part putrefies with confiderable quickneSs, and affords much ammoniack. The alkalis do not diffolve it, but acids combine with it. The nitrick acid diSengages much nitrogene, and aSterwards diffolves it with efferveScence, and diSengagement of nitrous gas. The refidue affords oxalick acid, and a Small quantity of the malick acid. This fibrous fubftance is of the nature of the mufcular fibre, which caufed Bordeu to call the blood fluid flefh ; and long be- fore the time of this celebrated phyfician, Paul Zacchia afferted that •« caro nihil aliud eft quam Sanguis concretus." (Queft. I.e. 3.. Y 554 Properties of Fat. galis, p. 239 ) This fibrous matter is more animalized than the lymph ; and it appears to be prepared by the very aa of circu- lation to concur in augmenting the parts of the human body. Blood contains much iron. The experiments of Menghini, Bocquet, and Lorry, prove that this metal is capable of paSIing into the blood by the firft paffages, fince patients who are under a courSe oS martial medicine void it by the way of urine. When the coagulated part of the blood has been wafhed, if that part which has retained the colouring matter be burned, and the coal lixiviated, the refidue of this lixivium is in the ftate oS Saffron of mars, of a fine colour, and uSually obedient to the magnet. The colour of the blood has been attributed to iron ; and it is very true that the colour appears to be entirely formed of it, for there exifts no veftige of this metal in the wafhed and dis- coloured coagulum : hut as, on the other hand, the blood does- not become coloured without the concourSe oS air, and as oxi* gene alone is abforbed in reSpiratron, it appears that the colour is owing to iron calcined by the pure air, and reduced to the ftate of red oxide. From this manner of conceiving the phenomenon, we may perceive why animal fubftances are fo advantageous in affifting and facilitating the red die, and why thefe fubftances take col- ours more eafily. CHAPTER IV. Concerning Fat. FAT is a condenfed inflammable juice contained in the cef- lular membrane : its colour Is ufually white, but Sometimes yel- low ; its tafte infipid ; and its confiftence more or leSs firm in the various Species of animals. In cetaceous and other fifh, it is nearly fluid j in carnivorous animals the fat is more fluid than in frugivorous animals, according to Mr. De Fourcroy. In the fame animal it is more folid near the kidneys, and under the Skin, than in the vicinity of the moveable viScera ; as the animal grows old, the fat becomes yellow, and more folid. ConSult De Fourcroy. To obtain fat in a ftate of purity, it is cut into fmall pieces ; the membranes and Smaller veflels are Separated ; it is waflied, then SuSed with a Small quantity of water, and kept in Sufion until all the water is evaporated. This laft fluid which floats above It, boils ; and when the ebullition ceaSes, it is a proof that all the water is diffipated. Fat has the greateft analogy with oils. Like them it is not miScible with water ; it forms foaps with alkalis j and burns in Acid of Fat. c ej the open air, by the contaa oS an ignited fubftance, at a fuffi- cient heat. Neumann treated the fat of the gooSe, of the hog, of the Sheep and of the ox, in a glafs retort by a graduated fire. He obtain- ed phlegm, an empyreumatick and brownifh oil, and a brilliant coal. ^He concludes from his analyfis that there is little differ- ence between fats *, and that of the ox appears only to contain a little more earthy matter. This very imperfea analyfis throws no light on the nature of fat; and we are indebted to Meffrs. Segner and Crell for experiments of a much more interefting kind. We Shall relate the chief. i. Beef fuet diftilled on the water-bath, in a glafs retort, af- fords oil and phlegm ; it forms foaps with potafh : the reddiffi phlegm has an acid tafte ; effervefces with alkali without red- dening the fyrup of violets, which affumes a brown colour by this mixture. 2. The marrow of beef affords the fame produas, excepting that a fubftance firft paffes over of the confiftence of butter. The phlegm has no fmell when cold. Fixed alkali occafions a weak effervefcence. Mr. Crell has inftruaed us in the means of obtaining a pecul- iar acid from fat, which is at prefent diftinguifhed by the name of the Sebacick Acid. He at firft attempted to concentrate this acid by diftilling off the phlegm ; but this did not fucceed, for the liquid in the re- ceiver was as acid as that in the retort. He then faturated all the acid with potafh, and obtained a browniSh fait by evapora- tion, which he fufed in a crucible, to burn the oil which con- taminated it. This fait by folution and evaporation, afforded a foliated fait. He poured four ounces of fulphurick acid upon ten ounces of the fait, and diftilled by a very gentle fire. The febacick acid paffed over in the form of a greyifh vapour ; and half an ounce, very fuming and acrid, was found in the re- ceiver. Crell obferves that, in order to fucceed in this oper- ation, the fait muft be kept a long time in fufion, without which the acid would be mixed with oil, which weakens its virtue. By diftillation of fat in a copper alembick, Mr. Crell obtained the pure acid. But the fire neceffary for this purpofe alters the veffel, caufes the tin to run off, and the acid itfelf becomes charged with copper. It has long been known that the alkalis form a kind of Soap with animal fat. Mr. Crell, by treating this Soap with a Solution of alum, Separated the oil, and obtained the Sebate of potafh by evaporation : the fulphurick acid afterwards diftilled from this Salt, decompofes it ; and by this means the febacick acid is Sep- arated. 5 56 Properties of the Acid of Fat. Mr. De Morveau melted Suet in an iron pot; and to this he added pulverized quicklime, taking care to ftir it continually at the commencement; at the end oS the operation, a confiderable heat was applied, taking care to raiSe the veffels, in order to avoid expoSure to the vapours. When the whole was cold, it was found that the Suet had no longer the Same Solidity. This was boiled in a large quantity of water ; and the lixivium, aSter fil- tration, afforded a brown acrid Salt, which is the Sebate of lime. This fait is foluble in water but would require too much time to purify it by repeated cryftallizations. This purpofe is more eafily anSwered by expofing it to a degree of heat capable of burning the oil; after which, a fingle folution is fufficient to puriSy it. It leaves its oil upon the filtre in the State of coalj and nothing more is then neceffary than to evaporate it. The folution uSually contains a Small quantity of quicklime, which may be precipitated by the carbonick acid. This Salt treated in the Same manner as the Sebate of potafh, affords the febacick acid. This acid exifts ready formed in Suet : two pounds afforded fomewhat more than Seven ounces to Crell. It exifts ready formed in the fat, fince earths and alkalis difengage it. It has the greateft affinity with the muriatick acid, as it Sorms with potafh a Salt which melts in the fire without being decern-. poSed ; it aas powerfully on gold, when riiixed with the nitrick acid ; it precipitates filver Srom the nitrate oS filver ; it Sorms a fublimate with mercury, and the folution of this fublimate is not rendered turbid by the muriate of foda. But though this acid approaches the muriate in feveral-refpeas, it differs from it in others, and hitherto feems to be nothing hut a modification of that acid. With foda, it forms cryftals in needles, and a cryf- tallized fait with lime. It decompofes common fait, &c. Mr. Crell obtained the acid of fat by diftillation from the buN ter of cacao. Spermaceti likewife affords it. The properties of this acid are the following : It reddens blue vegetable colours. It affumes a yellow colour by fire, and leaves a refidue, which announces a partial decompofition. From this circumftance, Mr. Crell confiders it as occupying the middle Space between the vegetable acids which are deftroyed by fire, and the mineral which receives no alteration. Its exiftence in the butter oS ca-, cao, and in fats, is favourable to the notions of Crell on this fub- jea. It attacks the carbonates of lime and alkali with effervefcence, and with them for the falts which Bergmann finds to be very Similar to the acetites with the fame bafis Acid of Fat. Bile. 507 This acid, as Mr. De Morveau obferves, feems to have fome aaion upon glafs. Mr. Crell having digefted it feveral times upon gold, always obtained a precipitate of white earth, which was not lime, but which he prefumes to have been carried up in the diftillation, and could only arife from the retort itfelf. This acid does not perceptibly aa on gold : but it attacks the oxide, and forms a cryftallizable fait, as it does likewife with the precipitates of platina. It unites with mercury and with filver ; yielding the latter to the muriatick acid, but not the former : It takes both from the fulphurick acid, lead from the nitrick and acetous acid, and tin from the nitro-muriatick acid. It attacks neither bifmuth, cobalt, nor nickel. It does not decompofe the fulphates of copper, of iron, or of zinc ; nor the nitrates of arfenick, manganefe, zinc, &c It reduces the oxide of arfenick by diftillation. Crell formed a febacick ether. # From this analyfis it appears that fat is a kind of oil or but- ter rendered concrete by an acid. Its ufes are—1. To keep up the heat of the body, and de- fend the vifcera from the impreflion of external cold. 2. To ferve as nourishment or Support Sor the animal on the occafions of want, ficknefs, &c. CHAPTER V. Concerning the Bile. THE Bile is one oS thoSe humours which it is effential to know, on account oS the influence and effea it has both in the ftate of health and diforder. We fhall even fee that its analy- fis is fufficiently perfea to afford inftruaion in an affinity .of cafes* This humour is feparated in a large vifcusof the lower belly, called the Liver ; it is afterwards depofited in a bladder, or re- fervoir, called the Gall Bladder •, from which it is conveyed in- to the duodenum by a particular channel. The bile is glutinous, or imperfeaiy fluid, like oil; of a very bitter tafte i a green colour, inclining to yellow j and froths by agitation like the folution of foap. -,'.,_ , If it be diftilled on the water bath it affords a phlegm, which is neither acid nor alkaline, but putrefies. This phlegm, acord- ing to the obfervation of Mr. De Fourcroy, often emits a fmell wfernblim; that of muik : bile itfelf has the fame property, ac- 5S-. Diftflhtthn and cording to the geneTal pofe it. The greenifh yellow colour of the excrements of in- fants'at the breaft, arifes from a fimilar decompofition ; and it i* the refinous part which tinges them. From the aaion of Habitudes of the Bile. 559 the bile upon acids, we may deduce thccffea of theSe remedies when the evacuations are putrid, and the degeneration of the bile is Septick. The lymph is then coagulated, and the excre- ments become harder. This fhews the reaSon why the excre- ments oS infants are fo frequently clotted. When the bile remains a long time in the firft paffages, as for example in chronical diforders, it affumes a black colour, - becomes thick, acquires the confiftence of an unguent, and forms a liming oS Several lines in thickncSs in the inteftinal canal, ac- cording to the observation of Mr. De Fourcroy. When fmear- ed on paper, and dried, it becomes green ; diluted with water, it forms a tinaure of a yellow green colour, from which a large quantity of black fcales are precipitated : with alcohol it like=. wife forms a black tinaure, and depofites that laminated brilliant Salt discovered in biliary calculi by Mr. Poulletier de la falle. This humour, which forms the atra bilis of the ancients, w nothing but the bile rendered thick ; and in this cafe the effea of acids, and the danger, of irritating Subftances, may be eafily accounted for. This thickening of the bile clogs the vifcera of the fewer belly, and produces obftruaions. Many diforders are referable to the predominant charaaer of the bile. On this fubjea, the interefting Memoirs of Mr. De Fourcroy may be confulted, in the colfeaion of the Royal Society of Medicine for the years 1782 and 17&3. When the bile becomes thick in the gall bladder, it forms the concretions called biliary calculi. Mr. Poulletier has paid great attention to the analyfis of thqfe ftones. He has obferved that they are foluble in ardent fpirit. When the folution is left to itfelf for a certain time, brilliant and light particles are feen in it, which Mr. Poulletier found only in the human calculi, and which appeared to him to have the greateft analogy with the fait of benzoin. Mr. De Fourcroy has obferved that the difcovery of Mr. De la Salle has been confirmed by the Royal Society (of Medicine,) which has received feveral biliary calculi that appeared to be> forined by a fait analagous to that which was obferved by this chemift. They confift of maffes of tranfparent cryftalline plates, fimilar to mica or talc. The fociety oS Medicine poffeffes in its colfeaion a gall bladder entirely filled with this Saline concre- tion. We may thereSore, as De Fourcroy obServes, admit of two kinds of calculi; the one are opaque, and are afforded only by the condenfed bile ; the others confift of the cryftals we have de- scribed. $6o Parts of Animals. Boerhaave obferved, long Since, that the gall bladder of oxen, , at the end of the winter, was filled with calculi, but that the frefh pafturage diffipated thefe concretions. Soaps have been propoSed as Solvents for thefe calculi. The academy of Dijon has published the SucceSs oS a mixture of eS- fence of turpentine and ether. Frefh vegetables, which are fuch fovereign remedies in deftroying thefe concretions, owe their virtue perhaps to the circumftance that they develope an acid in the ftomach, as we have obferved in treating of the gaf- trick juice. The ufe of the bile, in the animal economy, confifts, no doubt, in dividing thoSe Subftances which have undergone a firft digef- tion in the ftomach ; and giving an efficacy and force to the motion of the inteftines. When its flux is interrupted, it a- bounds in the blood, and the whole body becomes of a yellow tinge. The bile or gall is an excellent vulnerary externally applied : internally taken,, it is a good ftomachick, and one of the beft deobftruents the art of medicine poffeffes. This kind of reme- dies deferves the preference, as being more analogous to the constitution ; and bile is a proper medicine when the digeftion languishes, or the vifcera of the lower belly are clogged. Bile, like other Soaps, removes Spots of oil, or other greafy matter, from fubftances to which they are adherent. CHAPTER VI. Concerning the Soft and White Parts of Animals. THESE parts are perhaps lefs known than thofe of which we have juft treated ; but their analyfis is not lefs interefting : we may even affirm that is more fo •, becaufe the application of the knowledge we may acquire on this fubject, will daily pre- fent itfelf in the commonest purpofes of domeftick life. All the parts of animals, whether membranes, tendons, aponeurofes, cartilages, ligaments, or even the Skin and horns, contain a mucous fubftance very foluble in water, but not in alqohol, and known by the name of Jelly. Nothing need be done to obtain it, but to boil thefe animal Subftances in water, and concentrate the decoaion, until by mere cooling it affumes the form of a folid tremulous mafs. Jellies are very common in our kitchens : apd the cooks are perfeajy well acquainted with the methods of making them, and of giving them Solidity when the temperature of the atmof- Properties of Jellies. Portable Soups. $6,\ > phere Is very hot. This jelly of harts-horn is extraaed by a Similar operation, and aSterwards rendered white with the milk oS almonds. This kind oS food, duly Scented, is Served up at our tables by the name oS blanc manger. Jellies are in general reftorative and nourishing : that oS harts-horn is aftringent and emollient. Jellies in general have no Smell in their*natural ftate, and their tafte is infipid. By diftillation they afford an infipid and inodorous phlegm, which eafily putrefies. A ftronger heatcau- Ses them to Swell up, become black and emit a fetid odour ac- companied with white acrid fumes. An alkaline phlegm then paffes over, fucceeded by an empyreumatick oil, and a little car- bonate of ammoniack. A Spongy coal remains which is with difficulty reduced to afhes, and affords by analyfis muriate of Soda and phofphate oS lime. Jelly cannot be kept above a day in the Summer, or two or three in the winter. When it becomes Spoiled, white livid Spots are Sormed on its SurSace, which Speedily extend to the bottom oS the pots. A large quantity oS nitrogenous, hydro- genous, and carbonick gas is emitted. Water diffolves jellies perfeaiy. Hot water diffolves a large quantity, as they become confiftent only by cooling. Acids likewiSe diffolve them, and alkalis more eSpecially do. The nitrick acid diSengages nitrogene gas, according to the fine experiments oS M. Berthollet. When jelly has been extraaed without long decoaion, and has no lymph mixed with it, it then poffeffes moft of the char- aaers of the vegetable jelly : but it Is feldom obtained without a mixture of lymph 5 and in this cafe it effentially differs from the vegetable jellies, in affording nitrogene gas and ammoniack. If jelly be concentrated to fuch a degree as to give it the form of a cake, it is deprived of the property of putrefying; and by this means the dry or portable Soups are formed. The follow- ing is a receipt for preparing thefe cakes: Calves feet 4 Leg of beef 12 pounds. Knuckle of veal 4 pounds. Leg of mutton 10 pounds. Thefe are to be boiled in a fufficient quantity oS water, and the Scum taken off as uSual; aSter which the Soup is to be Sep- arated Srom the meat by Straining and preffure. The meat is then to be boiled a Second time in other water ; and the two decoaions, being added together, muft be leSt to cool, in order that the fat may be exaaiy feparated. The Soup muft then be clarified with five or fix whites oS eggs, and a Sufficient quantity 3...Z $62 Jellies. Glues. of common fait added. The liquor is then ftrained through flannel, and evaporated on the water-bath to the confiftence of a very thick pafte ; after which it is fpread rather thin upon a N Smooth ftone, then cut into cakes, and laftly dried in a ftove un- til it becomes brittle : thefe cakes are kept in well clofed bottles. The fame procefs may be ufed to mike a portable foup of the fleSh of poultry ; and aromatick herbs may be ufed as a feafon- ing, if thought proper. Thefe tablets or cakes may be kept four or five years. When intended to be ufed, the quantity of half an ounce is put into a large glafs of boiling water, which is to be covered, and fet upon hot afhes for a quarter of an hour, or until the whole is entirely diffolved. It forms an excellent foup, and requires no addition but a fmall quantity of fait. The cakes of ho ckiack, which are prepared in China and are known in France by the name of colle de pen d'dne, are made with animal fubftances. They are.ufed in diforders of the lungs in a dofe from half a dram to two drams. The nature of the fubftances made ufe of, and the method of operating, produce fome difference in thefe produas. -Old or lean animals afford in general better glue than the young and fat. For a full account of the art of making glue, confult L'Art defaire differentes Efpeces de Colle, par M. Duhamel de Monceau, de CAcademie des Sciences. r. To make the ftrong or Englifh glue, the parings of leath- er, the fkins of animals, with the ears of oxen, calves, fheep, Sec are ufed. Thefe matters are firft-digefted in water, to pene- trate the texture of the Skins ; they are afterwards fteeped in lime water, taking care to ftir and agitate them from time to time •, they are then laid in a heap for fome time, afterwards wafhed, and the fuperabundant water preffed out by a prefs. Thefe fkins are then digefted m water gradually heated to ebul- lition. The liquor is afterwards poured out, and feparated with preffure. Liftly, it is thickened by evaporation of the water by heat, and poured on flat poliShed ftones or into moulds, and left to dry and harden. This glue is brittle. It is Softened by heating it with a fmall quantity of water for ufe, and is applied with a bruSh. Car- penters and cabinet makers uSe it to Saften pieces of wood to- gether. 2. The glue of Flanders is merely a diminutive of the ftrong glue. It has not the fame confiftence, and cannot be ufed in glu- ing wood ; it is thinner and more tranfparent than the former. It is made with a more accurate choice of mirtrials, and with greater care. It is ufed bydefigners. Mouth glue is made-of Jelly. Glue'. Jfinglafs. 563 this, to Stitch paper together, by Suflng it again with the addi- tion oS a Small quantity of water, and four ounces of fugar candy to a pound of the glue. 3. The colle de gand is made with the clippings of white gloves, well fteeped in water, and boiled : it is likewife made with the clippings of parchment. In order that thefe two kinds of glue may be fit for ufe, it is neceffary that they be of the confiftence of a tremulous jelly when cold.* 4. FiSli glue, or ifinglafs, is made of the mucilaginous parts of a large fifh commonly found in the Ruffian feas. The Skin, the fins, and the nervous part, are cut into Slices, boiled on a flow fire to the confiftence of a jelly, fpread out to the thicknefs of a Sheet of paper, and formed into cakes or long pieces, fuch as we receive them from Holland. The filk manufaaurers, and more efpecially the ribbon weavers, ufe it to give a luftre to their goods ; it is alfo ufed to Stiffen gauzes, and to clarify or fine wine, by mixing a folution of this fubftance with it. Ifin- glafs enters into the compofition of fome platters. It is. excel- lent to correa acrid humours, and terminate obftinate venereal diforders. GUders fize is made by boiling eel fkins in water with a fmall quantity of lime ; the water is ftrained off, and fome whites of eggs added. When it is intended to be ufed, it is heated, ap- plied to the SurSace intended to be gilded, and when it is dry the gold leaS is laid on. 5. The glue oS Snails is made by expofing fnails to the Sun, and receiving in a glafs the fluid which flows from them. This liquor is mixed with the juice of milk thiftle. It is ufed to ce- ment glafles together, which are afterwards expofed to the fun to dry. 6. To make the glue of parchment, or parchment fize, two or three pounds of the clippings of parchment are put into a pail Df water. Thefe are boiled until half the water is evaporated after which the whole is ftrained through a cloth, and left to fettle. The glue or fize ufed in the paper manufaaories, to fortify the paper, and to repair its defeas, is made with wheat flour dif- fufed in boiling water, and ftrained through a Sieve. This fize muft be uSed the following day, and neither fooner nor later. The paper is afterwards beat with a mallet, fized a fecond time, put into the prefs, to fmooth and unite it, and afterwards tended by hammering. * Thefe weaker glues are called Size by our workmen, who apply the jiame of Glue to the Strong glue only. 564 Mufeular Parts. CHAPTER VII. Concerning tbe MuScular or Flefhy Parts. THE mufcles of animals are formed of longitudinal fibres conneaed together by the cellular membrane, and impregnated with various humours, in which we find partly thofe we have already examined feparately. The analyfis of theSe Subftances by diftillation afforded us lit. tie inftruaion refpeaing their nature. The produas were, wa- ter which eafily became putrid, alkaline phlegm, empyreumat- ick oil, carbonate of ammoniack, and a coal which aftbrdtd by incineration a fmall quantity of fixed alkali, and febrifuge Salt. The proceSs which Succeeds the beft Sor Separately obtaining the various fubftances which compofe mufcles, is the following which has been pointed out to us by Mr. De Fourcroy. i. The mufcle is firft wafhed in cold water : by this means the colouring lymph, and a Saline Subftanee, are taken up. By flow evaporation of this water, the lymph coagulates, and, may be Separated by the filtre j and a continuance of the evaporation affords the faline matter. 2. The refidue of the firft wafhing is digefted in alcpho", which diffolves the extraaive matter, and a portion of the fait \ the extraa is feparated by the evaporation of the alcohol. 3. The refidue of the firft operations is to be boiled in water, which takes up the jelly, the fat part, and the remaining faline and extraaive matter. The fat oil Swims on the furface and may be taken off. 4. After thefe operations, there remains only a white infipid fibrous fubftance, inSoluble in water ; which contraas by heat, like other animal Subftances ; affords ammoniack, and very fetid oil, by diftillation. Nitrogene gas is obtained from it by the nitrick acid. It poffeffes all the charaaers of the fibrous part of the blood in which fluid it is armed, to be afterwards depofited in the mufcles, where it receives the_ laft. charaaer appropriated to it. Mr. Thouvenel, to whom we are indebted for interefting re- fearches on this fubjea, has found in flefli a mucous extractive fubftance, Soluble in water and in alcohol, poffeffing a peculiar tafte which jelly has not; and when this fubftance is very much concentrated, it affumes an acrid and a bitter tafte. Fire devel- opes an aromatick flavour in it. This fubftance evaporated to •IryneSs, affumes a bitter, acrid, and Saline tafte. It Swells up Analyfis of Flefh. $65 upon hot coals, and liquefies; emitting an acid, penetrating Smell, reSembling that oS burned Sugar. It attraas the humid- ity of the air, and forms a faline efflorefcence. In a hot atmof- phere it becomes four, and putrefies. All thefe charaaers indi- cate a refemblance between this fubftance, the faponaceous extraas, and the faccharine matter of vegetables. Mr. Thou- venel, who has likewife analyfed the fait obtained by the decoc- tion and flow evaporation of flefh, obtained it fometimes In form Of down, and fometimes in that of cryftals, whofe figure he could not defcribe. This fait appeared to him to be a phofphate of potafh in frugivorous quadrupeds, and muriate of potafh in carnivorous reptiles.' It is probable, as Mr. De Fourcroy ob- ferves, that'this Salt is a phoSphate of foda or of ammoniack, mixed with the phofphate of lime. Thefe falts are indicated, and even with excefs oS acid, like thoSe of urine, by lime-water and ammoniack, which form white precipitates in the decoaion of flefh. The moft abundant part of mufcles, and that which consti- tutes their predominating charaaer is the fibrous matter. The charaaers which diftinguifh this fubftance are— i. It is not foluble in water. 2. It affords more nitrogene gas by the nitrick acid than other fubftances do. 3. It aSter- wards affords the oxalick acid, and the malick acid. 4. It pu- trefies eafily when moiftened, and affords much concrete ammo- niack by diftillation. The other three fubftances, contained in flefh, namely, the lymph, the jelly, and the Sat part, are the Same Subftances con- cerning which we have already treated, under the Same denom- inations. , From theSe principles we may give the etiology of the form- ation of foup, and follow the fucceffive diSengagements of all the principles we have fpoken of. The firft impreffion of the fire, when a foup is made, is the difengagement of a confiderable fcum, which is taken off until it no longer appears. This fcum arifes merely from the difen- gagement of the lymph, which coagulates by the heat. It af- Sumes, by the impreflion of the fire, a red colour, which it does not naturally poffeSs. At the Same time the gelatinous part i? diSengaged, which re- mains diflblved in the Soup, and congeals only by cooling. It forms on the SurSace oS cold Soup a body more or leSs thick, according to the nature of the fubftances, and the age of the animate; for young animal afford a larger .quantity than fuch ■it are old. $66 Concerning Urine. As foon as the flefh is penetrated by heat, flat round drops ariSe, and float at the SurSace oS the fluid, in which they are not aSterwards diffolved, but congeal by cooling, and exhibit all the charaaers oS Sat. In proportion as the digeftion proceeds, the mucous extraa- ive part Separates : the foup becomes coloured, affumes its pe- culiar odour and tafte ; and it is more particularly to this princi- ple that its properties are owing. The fait which is at the fame time diffolved takes off the in- fipidity of all the before mentioned principles : and at this pe- riod the foup is completely made. According to the nature of the feveral principles which are diSengaged, and the order in which they appear, it- is evident that the management oS the fire is not a matter of indifference. IS the ebullition be haftened, and a proper time be not allowed for the difengagement oS the mucous extraaive matter, the three inodorous and infipid principles are obtained; and this is obServed in Soups made by cocdes who are haftened, or have not time allowed to pay a due attention to their work. When on the contrary, the digeftion is made over a flow fire, the princi- ples Separate one after the other, in order ; the Skimming is more accurately performed ; the aromatick flavour which is difr engaged combines more intimately, and the foup is of an excel- lent flavour. Thefe are the foups of the good women who per- form better with a fmall quantity of meat, than profeffed cooks with their ufual prodigality, and in this cafe we may fay that the form is of more value than the fubftance. The heat muft not be applied too long ; for the great evap- oration, by concentrating the principle of Smell and tafte at the Same time with the Salt, renders them acrid and bitter. CHAPTER VIII. - f Concerning Urine. URINE is an excrementltious humour cf the body ; and it is one of the fluids of which it is of the greateft importance to poifefs an accurate knowledge; becaufe the praaical phyfician may derive the greateft advantage from information of this na- ture. It is known to what a degree of extravagance the mar- vellous pretenfions of this kind have been carried. The de- lirium has proceeded to fuch a height, as even to pretend to af- certain Srom the urine, not only the nature of the diforder, and the character of the patient, but likewife the fex and condition. CharaBers of Urine. £67 The true phyfician has never given into this excefs: but he has always derived affiitance, in his praaice, Srom the charac- ters exhibited bv the urine ; an 1 this is the humour Srom which he may draw the m )(t fatisfid >ry indications. It carries out, as we may fay, the internal charaaer ; and a phyfician who knows how to form a ju tgment upon its properties may deduce the moft inftruaive confequences from it. Munro, in his Treatife of Comparative Anatomy, his deScribed the organs which, in birds, Supply the place oS the kidneys : they are placed near tbe vertebral column ; and communicate, by two duas, to the vicinity oS the anus. He affirms that the urine oS birds is that whitifh Subftanee which almoft always accompanies the excrements. Chemical analyfis ought to enlighten the phyfician in his re- Searches concerning the Urine. She nature of the principles it carries off in certain circumftances, affords vaft information refpeaing the predominant principle in the fluids of the human body. Its various ftates mew the difpofition of the conftitution. Perfons of a very irritable habit have the urine of a lighter col- our than others; gouty perfons evacuate turbid urine ; and it has been obferved that, when the bones become foft, the urine carries off the phofphate of lime, which conftitutes their bafis ; inftances of which were obferved in the perfons of Mrs. Supiot, the widow Melin, &c. The various ftates of any diforder are always pointed out by the ftate of the urine ; and the truly praaical phyfician will there obferve Signs of crudity and con- coaion which will direa his proceedings. Urine is likewife an humour interefting to be known on ac- count of the various ufes to which it is applied in the arts, b was from this fubftance alone that phofphorus was, for a long time extraaed ; it is to this fluid that we owe the developement of the blue colour of turnfole, and the violet of archil; it may be fuccefsfully employed in forming artificial nitre-beds ; it power- fully contributes to the formation of fal ammoniack ; it may be ufed to prepare the alkali in the minufaaure of Pruflian blue ; and, in a word, it may be applied in all the operations wherein the concurrence of an animal humour is required. Urine, in its natural ftate, is tranSpirent, of a citron yellow- colour, a peculiar fmell, and a faline tafte. It is more or lefs abundant, according to the feafons, and the ftate of the individual. It is futlfeieut to obferve, on this fub- jea, that tranSpiration, and more eSpecially perSpiration or Swei', Supply the place of the Secretion oS urine ; aim th«t con- sequently, when the tranSpiration U great, the urine is net abun- dant. 5^8 Analyfis of Urine. Phyficians diftinguifh two kinds of urine. The one is emit- ted one or two hours after drinking ; this is aqueous, contains fcarcely any falts, and has neither colour nor Smell : it is this which is evacnated So plentifully during a courfe of mineral wa- ters. The other is not evacuated until after the funaions of fanguification are finifhed : and may be called Faeces Sanguinis. This is all the charaaers we have enumerated and affigned to urine. It is carried by the arteries into the kidneys, where it is feparated, and poured into the receptacles of thefe organs, whence it paffes, by the ureters, into the bladder ; where it re- mains a longer or Shorter time according to the habitude of the perSon, the nature of the urine, the irritability or magnitude of the bladder itfelf. The urine has been long confidered as an alkaline fluid : but in our time it has been proved to contain an exceSs oS acid. It appears Srom the experiments oS M. Berthollet— i. That this acid is of the nature of the phofphorick acid. 2. That the urine of gouty perfons contains leSs of tbis acid ; whence he conjeaures, with reafon, that this acid retained in the blood, and conveyed into the articulations, produces an irritation, and confequently a flux of humours, which caufe pain and fwelling. The analyfis of urine by diftillation has been accurately made by various chemifts, but more efpecially by Rouelle the younger. Much phlegm is obtained, which putrefies with the greateft fa- cility, and affords ammoniack by its putrefaaion, though It does not itfelf contain that fubftance. At the fame time a fubftance is precipitated of an earthy appearance, but which in reality is a true phofphate of urine. It is this fame fait which forms the Sediments of urine, which is obferved by expofing it to cold dur- ing the winter, even though the urine be of a perfon in perfea health. When urine has, by a fufficient evaporation, acquired the confiftence of fyrup, it need only be expofed, in a cool place, to obtain cryftals, in which analyfis has proved the exift- ence of the phofphates of foda and of ammoniack. This pre- cipitate of cryftals has been diftinguifhed by the name of fufible fait, native fait, microcofmick Salt. Urine may be deprived of all faline matter by repeated folutions, filtrations, and evapora- tions ; the matter which adheres to thefe cryftals, and of which they may be cleared by thefe operations, is foluble partly in al- po'hol and partly in water. The Saponaceous Subftanee, or thrt which is Soluble in alcohol, is capable of cryftallization, dries difficultly, and affords by diftillation a fmall quantity of cii, carbonate of- ammoniack, Of muriate of ammoniack, and tie refidue converts fyrup of vialets to a green. 1 he extraaive principle is eafily dried, and exhibits the Same phenomena in. diftillation as animal Subftances. See Rouelle. . Analyfis. of Urine. $69, The phenomena exhibited by the fponraneous decompofition of urine are very interefting to be known ; on which fubjea An excellent memoir of Mr. Halle in the volume of the Society. of Medicine for 1779, may be confulted. Urine left to itfelf foon lofes its Smell, which is Succeeded by a fmell of ammoniack, which is likewife diffipated in its turn. The colour becomes brownifh, and the fmell fetid and naufeous. We are indebted to Mr. Rouelle for a valuable observation—that crude urine, urina potus, prefents very different phenomena ; and that it be- comes covered with mouldinefs, like the expreffed juices of vegetables. Putrefied urine has much lefs acid in the diSengag- ed ftate than when it is Srefh. The fixed alkalis and lime difengage much ammoniack from urine by decompofing the phofphate of ammoniack. The acids deftroy the fmell of urine by combining with the ammoniack, which is the principal vehicle of that fmell. We may therefore confider urine, in its natural ftate, as wa- ter holding in folution matters purely extraaive, and phofphor- , ick or muriatick falt3. TheSe phofphorick Salts have lime, am- moniack, cr Soda, Sor their bafis ; we fliall take a flight view of each In particular. That which is called fufible fait, is nothing but a mixture of all the falts contained in urine, clogged with the extraaive prin- ciple. All the ancient chemifts advifed evaporation and repeat- ed filtration, to clear them from this animal extraa; but Meffrs. Rouelle and the Duke de Chaulnes have obferved, that great part of the felt is difengaged and diffipated by thefe operations to fuch a degree that three fourths are loft. To avoid moft of this lofs, the Duke de Chaulnes advifes folution, filtration, and Cooling in well clofed veffels. Two ftrata of fait are then ob- tained ; the upper of which appears to have the form of Square tables, wherein Rouelle obServed tetrahedral priSms flattened with dihedral Summits. This is the phoSphate of foda : and be- neath this lies another fait cryftallized in regular tetrahedral prifms, and is tbe phofphate of ammoniack. 1. The phofphate of ammoniack ufually exhibits the form of a verv compreffed tetrahedral rhomboidal prifm : but this form varies much ; and the mixtures of the phofphate or muriate of foda cauSe an infinity oS modifications in it. The tafte of this fait is cool, afterwards urinous, bitter and pungent. ^ This falts Swells up on the coals, emits,a ftrong fmell of am- moniack, and melts by the blow pipe into a very fixed and verf fufible glafs. 4...A 57 o Phofphate of Soda. . It is'Soluble in water. Five parts of cold water, at ten degrees of.Reaumur, diffolved only one of this fait, but at theremper.i- ture of fixty degrees this fait is decompofed, and a portion of its acid is volatilized. It ferves as a flux to all the earths ; but-in this cafe its alkali is difengaged, and the phofphorick acid unites with the earth, as I, find by experiment. Bergmann propofed it as a flux. The fixed alkalis and lime-water diSengage the ammoniack. When this Salt is heated with charcoal, it affordsphoSphortis. ■ 2. The phoSphate of foda was made known in 1740 by Haupt, under the name of fal admirable perlatum. Hellot be- fore him, and Pott feventeen years after him, took it for felen- ite. Margraff gave an accurate defcription of it in his Memoirs, in 1745 ; and Rouelle the younger defcribed it at full length in 1776, under the name of fufible fait with bafe of natrum. All agree that it differs from the preceding in not affording phof- phorus with charcoal. According to Rouelle, its cryftals are flattened irregular te- trahedral prifms, with dihedral fummits. The four fides of the prifm are two irregular alternate pentagons, and two longrhom- bi truncated. Slope wife. When expofed to heat it fufes, and affords a glafs wliich be - comes opaque by cooling. It is foluble in diftilled water and the folution turns fyrUp of violets green. It does not afford phofphorus with charcoal. Lime difengages the foda. It may even be obtained in a cauf- tick ftate, if the precipitation be effeaed by lime water. The mineral acids, or even diftilled vinegar, decompofe it by feizing its alkali. Mr. Prouft, to whom we are indebted for all the accurate information we poffefs concerning thefe fubftances was of opinion, that the bafe to which the foda adhered was not the phofporick acid, but a very Angular fait, whofe properties greatly refemble thoSe of the acid of borax. He found this fait in the mother water, after having decompofed the phoSphate of Soda by the acetous acid, and obtained the acetite of foda by cryftallization. He obtained this fame Salt by diffolving and evaporating the refidue of the diftillation of phofphorus. One ounce of phofphorick glafs contains five or fix drams. This fait was chara&erifed by the following properties : 1. It cryftallizes in parallelograms. 2. Its tafte is alkaline, and turns fyrup of violets green. 3. It fwells up in the fire, reddens, and melts. 4. It efflorefces in the air. This may not take place when the phofporick acid has not been fufficiently decompofed by the diftillation to leave the alkali diSengaged, as I have obServed. Calculus of the Bladder. 5*71 5. Boiling water diffolves fix gros per ounce. 6. It affifts the vitrification of earths, and forms a "perfea glafs with Silex. 7. It decompofes nitre and marine Salt, and Separates their acids. 8. It is infoluble in alcohol. Mr. JClaproth has published in Crell's Journal an analyfis of the Sufible Salt, in wnich he has Shewn that the pearly Salt, or Salt oSProuft, is merely the phoSphate oSScda. To prove this nothing more need to be done than to diffolve this Salt in water and to add a Solution oS nitrate of lime. The nitrick acid feizes the foda, and the phofporick acid is precipitated with the lime. The phofporic acid may afterwards be feparated by means of the fulphrick acid. If the phofphorick acid obtained by the flow combuftion of phofphorus be faturated with foda Slightly in exceSs, the Sufible Salt is Sormed ; if this'excefs be taken up by vinegar, or if more phofphorick acid be added, the fubftance defcribed by Prouft is formed. The phofphate of foda is not decompofable by charcoal; and it is at prefent clearly feen why the fufible fait affords but little phofphorus ; and why Ku^ckel, Margraaf, and others recom- mended a mixture of the muriate of lead ; for by this means the phofpate of lead was formed, which permits the decompo- fition of the phofphorick acid, and affords phofphorus. Concerning the Calculus of the Bladder. Paracelfus made Some reSearches concerning the calculus of the bladder which he calls duelech. He confiders it as a Sub- Stance intermediate between tartar andflone, and thinks that its Sormation is owing to the modification of an animal refin : he fuppofies it to be abSolutely fimilar to the matter oS the gout. Vanhelmont does not admit of this analogy; and confiders the calculus as an animal coagulum produced by the falts of urine, and a volatile earthy fpirit. Boyle found this calculus to be compofed of oil and volatile fait. Boerhaave fuppofed it to confift of a fubtle earth, intimately united with alkaline volatile falts. Hales has obferved that a calculus of the weight of two hundred and thirty grains afforded fix hundred and forty-five times its volume of air, and that there remained only a calx of the weight of forty-nine grains. Independent of this chemical information, fome phyficians, fuch as Alfton, De Haen, Vogel, Meckel, &c. had obServed the folvent power of foap, lime-water, and alkalis. S7* Calculus of th* Bladder, But we poffeffed no accurate ideas on this Subjea until it was ferioufly taken up by Scheele and Bergmann. The bezoar oS the bladder is Sormed for the moft part of a peculiar concrete acid, which M. De Morveau calls the Lithiafick Acid. (The Ency- clopedic Methodique may be confulted, from which the prefent article is an extract.) \ The calculus is partly foluble in boiliftg water. The lixivi- um reddens the tinaure of turnfole ; and by cooling depofites moft of what it had diffolved. The cryftals thus Separated are the concrete lithiafick acid. Scheele has likewife obferved—i. ■ That the fulphurick does not diffolve the calculus unleSs affifted by heat, and that it is then converted into the ftate of fulphureous acid. 2. That the muriatick acid has no aaion upon it. 3. That the nitrick acid diffolves it with effervefcence, and diSengages nitrous gas and carbonick acid. This Solution is red $*it contains a diSengaged acid, and tinges the fkin oS a red colour. This Solution is not precipitated by the muriate of barytes, nor rendered turbid by by the oxalick acid. 4, That the calculus was not attacked by the carbonate of pot afh ; but that the cauftick alkali diffolved it, as well as the volatile alkali., jg. That one thouSand grains of lime-water diffolved 5^37 by mere digeftion, and that it was again precipitated by acids. . 6, That all urine even that oS in- fants, held a fmall quantity of the matter of calculus in folntion ; which perhaps may be the caufe, that. when, tbis matter:finds a nucleus in the bladder, it more, eafily encruSts it. I have Seen a calculus with a large plum Stone in its centre. 7. That the brick coloured depofition from the urine in fevers; is of the na- ture of the calculi. Thefe experiments exhibit feveral important confequences with regard to the compofition oS the calculus, and the proper- ties of the lithick acid. The calculus contains a fmall quantity of ammoniack. The coaly refidue of, the combuftion indicates an animal fubftance of the nature of jelly. The celebrated Scheele did not find it to contain a particle of calcareous earth ; but Bergmann pre- cipitate d,a true fulphate of lime, by pouring the Sulphurick in- to the nitrous Solution of the calculus. He admits that the . Jime is very fmall in quantity, as it rarely exceeds the two hunr dredth part of the entire weight. The fame chemift has detea- ed a white Spongy Subftanee, not Soluble in water, nor attacked by Spirit oS wine, or acids, or alkalis, which at laft affords a coa" of difficult incineration, and which the nitrick acid does not dif- folve, even in the ftate of afhes ; but this matter exifts in fo fmall a quantity, that he could not procure enough to examine. Arthrftick Concrethns*. 57? it. The calculus is not therefore analogous to bones in its na- ture ; neither is it a phoSphate oS lime, as has been pretended. TheSe are tbe reSults oS the chemifts of the north ; but I muft obServe that, aSter having decompofed many calculi by the cauf- tick alkali, I have precipitated lime, and Sormed phoSphates of potafh. Some phyficians, Such as Sydenham, Cheyne, Murray, See. have thought that the arthritick concretions were oS the Same nature as the calculus. The uSe which Boerhaave made of al- kalis in the gout ; the virtues admitted by Fred. Hoffman in the thermal waters of Carlefbad, which contain foda, with an excefs of carbonick acid ; the authority of Springsfeld, who af- ferts that the calculus is very fpeedily diffolved in theSe waters, even in the urijpe of thoSe w ho drink them ; the SucceSs of lime water, ufed by Alfton in the gout—all confplre to give fome credit to the opinion of thefe early phyficians. But the Sol- lowing experiments do not agree with this notion. VanSwieten affirms that the arthritick concretion neve* ac- quires the harShnefs of the calculus. Pinelli (Philof. Tranf.) diftilled in a retort three ounces of the arthritick matter colfeaed .from the articulations of feveral gouty perfons ; and he obtain- ed ammoniack, with Some drops of oil, the refidue weighing {wo gros. This refidue, which was Soluble in the muriatick, Yrilphurick and acetous acid, was not attacked by volatile alkali. An observation oS Mr. Rcering was published in the memoirs of the academy of Stockholm for 1783, which afcertains that the concretions expeaorated by an old man fubjea to the gout, were found to be of the nature of bone, or phofphate of lime. But one of the neweft and moft important faa9 is that of Wat- fon, in the Medical Communications of London, vol. i. 1784. He concludes, from the examination of the arthritick concretions of a gouty body, that this fubftance is very different from the matter of the calculus, fince it is foluble in rhe fynovia, and ea- fily mixes with oil and water, which the calculus does not. It Sollows from our obfervations on the lithick acid, that this acid is concrete, and fparingly Soluble in water ; that it is de- composed', and partly Sublimed by diftillation. This acid de- compoSes the nitrick acid, unites with earths, alkalis, and me- rallick oxides. It yields its bafes to the weakeft vegetable acids not excepting the carbonick. 574 Difcovefy of Phofphorus. CHAPTER IX. Concerning Phofphorus. PHOSPHORUS is one of the jnoft aftoniftiing produas of chemiftry. It is pretended that^traces of the .knowledge of this fubftance exift in the writings ofthe earlieft chemifts : but the moft ipofitive information we poffefs on this fubjea is found in thehiftory,given by Leibnitz, in the Melanges.de Berlin for 1710. He gives the difcovery to Brandt, a chemift of Hamburgh, ,who.during a courfe of experiments upon urine, with a view of extraaing a fluid proper to convert filver into_gold, difcovered phofphorus in the year 1667. He communicated his difcovery to.Kraft, who Showed it to Leibnitz, and being- qfttrwards ,in England he communicated it to Boyle.* Leibnitz caufed the fijft inventor to be introduced to the Duke of Hanover, before ■whom he performed the whole operation ; and a fpecimen ofthe < phofphorus was fent to Huygens, who Showed it to the Acade- my, of Sciences at Paris. It.is faid that Kunckel had affociated himfelf with Kraft to .purchase the procefs from Brandt. But Kunckel having been deceived by Kraft, who kept the fecret to himfelf,.knowing that urine was made ufe of, fet to work, and difcovered a procefs for making the fubftance ; and it is thib which led chemifts to call it by the name of Kunckel's Phofphorus. * As Boyle communicated the procefs for making phofphorus to the Royal Society asa di'covery of his own, and it is entered as Such in the "Phiiolophical Tranfaetions, 1 cannot avoid animadverting on this lmpeach- meat of his integrity, which is copied from one chemical book into ai.o- • tber. It is grounded on no better foundation than the affertion of Kraft, a dealer in Secrets, who, after having deceived his friend Kunckel, affo- ciated.with him for the purchafe of this fecret. 1 might infitt, 111 defence of the candour ar.d otherwife unimpeached integrity of Boyle, that his af- fertion ought infinitely to outweigh that ot the other. Not to mfift, how- ever upon this, it may be noticed that this new and famous product was known to have been extritfed from urine ; that Kunckel is univerfally ad- mitted as the difcoverer, from his having formed it upon no fuller inform- ation than this ; th it Boyle might with equal probability be admitted to have difcovered it in the fame manner, and upon information equally flight; and that the probability of this is rendered incomparably greater by the con lideration that none of thefe chemifts made any complicated experiments, but merely applied the force of fire to uiine ui.ul thii product at laft came over. T. Procefs for making Phofphorus. 575 Though the procefs was rendered pubiick, Kunckel, and a German called Godefred Hatwith,f were the only perfons who prepared phofphorus for a long time, ft was not till the year 1737, that it was made in the laboratory of the Royal Garden ar Paris. A foreigner executed this operation in the prefence of Meffrs. Helbt, Du Fay, Geoffroy, and Du Hamel. An ac- count of the operation may be feen in the volume of the Acad- emy for 1737. Hellot has collected all the effential circum- ftances. Margraaf, in the year 1743, published a new and more eafy method, which has been followed until Scheele and Glian taught us to obtain it from bones. The procefs of Margraaf confifts in mixing the muriate of lead, which remains after the diftillation of four pounds of min- ium and two of fal ammoniack, with ten pounds of the extract of urine of the confiftence of honey. Half a pound of charcoal in powder is added ; the mixture is dried in an iron pot until it is reduced to a black powder. This powder is to be put into a retort; and the volatile alkali, the fetid oil, and the fal am- moniack, diftilled off The refidue contains the phofphorus. It is affaved by throwing a fmall quantity on hot Coals : if st emits a fmell of garlick, and a phofphorick flame, it is to be put into a good earthen retort, and diftilled. Much more phofpho- rus is obtained bv this than by the old procefs ; and this de- pends on the addition of the muriate of lead by Margraaf, which decompofes the phofphate of foda, forming a phofphate of lead, which affords phofphorus ; whereas the phofphate of foda is not decbmpofable by charcoal. The famous chemift of Berlin has likewife proved that it was the fufible fait of urine which affords the phofphorus. Mr. Gahn publifhed in the year 1769, that the earth of cal- cined bones confided of lime united with the acid of urine ; but S^ele was the firft to prove that by decompofing this Ud of bones bvthe nitrick aril Sulphurick acids, evaporating the refi- due in which the phofphorick acids exift in a difengaged ftate, ' and diftilling the extraa with powder of charcoal, phofphorus is obtained. Thefe circumftances, related by Bergmann bimfeft in his notes to the Chemiftry of Scheffer, attribute to Schefcfe the difcovery of extraaing phofphorus from bones. ^ It ™ not until the year 1775 that the procefs was publifhed in the Ga- zette SaluTaire de Bouillon. Additions and improvements hav«e bten fucce-ffively made in this procefs of which accounts may dc feen in the Diftionnaire Encyclopedique. , , . , The procefs which has moft conftantly Succeeded with me, is the Sollowing : f Spelled Hanckwitz by moft authors. He was instructed by Boyle. T- 576" Phofplurus and Phajphoriek Glafs. The hardeft bones are Selected and bur,ned. By this combuf- tion the external part becomes white, white the internal part u blackifh. TheSe burned bones muft then be pulverized, and put into a turine, or in a round hooped wooden veffel. Half the weight of oil of. vitriol is then to be poured on, and conftantly Stirred. During the agitation a considerable heat is excited. The mix- ture mult be left in a digeftion for two or three days ; after which, water muft be gradually added, and ftirred. I digeft this laft mixture upon the fire, in order to increafe the. Solvent power of the water. The water of the lixivium is then to be evapprated in veffels of ftone ware, filver, or copper. Mr. Pelletier Tecommends this laft metal; becaufe, according to him, the phofphorick acid does not attack copper. The evaporation muft be carried to dry- nefs : more boiling water muft be poured on the refidue; and this wafhing muft be continued until the matter be exhaufted, which may be known by the water being no longer tinged yel- low. All theSe waters are to be evaporated, and afford an ex- traa. ** To feparate the fulphate of lime, the extraa muft be diffolved in the leaft poffible quantity of water, then filtered, and the fait remains on the filtre. This extraa may be mixed with powdeV of charcoal, and diftilled; but I prefer converting it into ani- mal glafs : for which purpofe I put the extract into a large cru- cible, and urge the fire. It Swells up at firft, but at laft Settles ; and at that inftant the giaSs is made. This glafs is white, of "a "milky colour. Becher was perfeaiy acquainted with it; but concealed his procefs, on account of the abufes which, according to him might be made of it—propter varios abufus. He tells us, in proper terms, homo vitrum eft, et in vitrum redigi potejl, ftcut tft omnia ammalid. He regrets that the Scythians, who drank out pf dlfguftjng feulls, were not acquainted with the art of convert- ing them into glafs. He Shews that it would be poffible fo form a feries of one's anceftors in glafi., in the fame manner as \ye poffefs them in painting, &c I obferved once to my great aftonifhment, that the phofphot- ick glafs I had juft made, emitted very ftrong efearick Sparks1; theSe flew to the hand at the diftance oS two inches. I exhibit- ed this phenomenon to my audience oS pupils. This glafs loft "the property in two or three days, though preServed in a capSule of common glafs. It fometimes happens that this glafs is deliquefcent, but it is then acid ; and this circumftance arifes from top large a quan- t)iftillation, &c. of Phofphorus. 577 ttty of fulphurick acid, or from this acid not having been fatur- ated by a digeftion oS Sufficient continuance. I have likewiSe obtained glaSs oS the colour of turquoife, when I perSormed the evaporation in copper veffels. This glafs may be deprived of the bubbles it ufually contains, by keeping it Sor a time in a violent heat; it is then transparent, and may be cut like a diamond. According to Crell, its Speci- fick gravity is to thatoS water as three to one, while that of di- amond is as three and a half to one. This glafs, is inSoluble in water, &c A fkeleton oS nineteen pounds, burned, affords five pounds of phofphorick glafs. I pulverize this glafs, mix it with equal parts of powder of charcoal, put it into a porcelain retort well coated, the beak of which I partly plunge into the water ofthe receiver, fo that noth- ing can efcape but air or phofphorick gas. I adapt a large tube to the tubulure of the receiver, and plunge it into a veffel filled with water. The fire being raifed by degrees, the phofphorus comes over the moment the mixture is ignited. The phoSphorus Sublimes, partly in the form of a fume which congeals ; and is precipitated upon the furface of the water, partly in the form of inflammable gas, and partly refembling melted wax, which drops in beautiful tranfparent tears from the neck of the retort. The theory of this operation is eafily explained. The phofphor- ick acid is difplaced by the fulphurick acid, as is Shewn by the large quantity of fulphate of lime which is obtained. All the other operations tend only to concentrate this phofphorick acid which is ftill combined with other animal fubftances, and the diftillation with charcoal decompoSes the phoSphorick acid ; its oxigene unites with the coal, and affords a carbonick acid, while the phoSphorus itSelS becomes diSengaged. To puriSy the phoSphorus, a piece oS chamois leather is moift- ened, and the maSs oS phoSphorus is put into it. This being immerSed in a veffel of boiling water, the phofphorus melts, and and is paffed through the Skin like mercury. The fkin cannot be uSed more than once j the phoSphorus, which might be paffed a fecond time, would become coloured. This proceSs was con- trived by Mr. Pelletier. In order to form phofphorus into fticks, a Sunnel with a long neck may be uSed, the lower orifice being cloSed with a Small cork, or piece oS Soft wood. The funnel is then to be filled with water, and phofphorus put in it; and this being plunged in boiling water, the heat is communicated to that of the funnel; and melts the phofphorus, which runs into the neck, and takes that form. The funnel is then removed into a veffel of cold water j and when the phoSphorus is perfeaiy cooled, the cork 4-.B --I78 ■'Properties efPhofphorous. is taken out, and. the phofphorus thru ft out of its mould with a Small piece of wood. Phofphorus is kept under water. After a certain time it lo- fes its tranfparency, becomes covered with a white powder, and the water is acidulated.* In whatever manner phofphorus may be made, it is always one and the Same Subftanee, charaaerized by the following properties : It is of a ffefih colour, and evidently tianfpareht. It has the confifterrce of wax ; and may be cut in pieces witb a knife, or twifted a Sunder with the'fingers ; in which laft cafe the precaution muft be taken of frequently plunging it into wi- ter> to prevent its taking fire. When phofphorus is placed in contaa ..witty the air, it emirs a white fume. . It is luminous in the dark ; and a folid Slick of phofphorus may be ufed to write with, like a crayon. The marks are vifible in the dark ; and this means has often been ufed to create fear and aftonifhment in the minds of the igno- rant. When phofphorus is expofed to twenty four-j- degrees of heat it takes fire with decrepitation, burns with a very bright flame, and emits a very abundant white fume which is luminous in the dark. The refidue ofthe combuftion is a red cauftick fubftance which attraas the humidity of the air, and becomes refolved into a hqior. This is the phofphorick acid, which we Shall proceed to treat of. Mr. Wilion affirms that the folar rays fet fire to phofphorus; and proves that this flame has the colour proper to the phoSpbo- rus, and not that of the ray itfelf.—Letter of Mr. Wilfon to Mr Euler, read at the Royal Society of London in June, 17J79. An advantageous ufe has lately been made pf the combuftiple propertyof phofphorus,to procure fire conveniently,andin all Situ- ations, by means of phofphorick tapers or matches, and the phi- lofophicaljhottfes, the method of making which we Shall pointout. * This flow acidification ofthe phofphorus feems to be reverfed by the fun's light. Sticks of phoSphorus, which had become covered, with a wnite powder, were expofed under water to the fun's light, which con- vert them, to an otange yellow colour in Such parts as were acted upon by the direct, light. .This fact appears to be ofthe fame nature as the col- ouring of the nitrous acid, and other fimilar phenomena. T. -|- Twenty-four degrees of Reaumur anfwer to eighty-fix of Fahrenheit. The vivid combuftion of phofphorus take's place a< different temperatures, according to its purity; but the prefent is very low. By taking phof- phorus into a freezing atmoSphere,its hunt flame difappears, and it Seems to require.a temperature ef fixty degres to revive it. I found the. Vivid corabuftioa. to take place at one hundred and fixty degrees. . T. Phofphorick Bougies. 57$*" i. The moft Simple procefs for making the phofphorick match- eSj.confifts in taking a glaSs tube, Sour inches long ^ and one line in diameter, cloSed at one end. A Small quantity of phofpho- rus is introduced into the tube, and puftied to its further end ; after which a taper covered with a fmall quantity of wax is in- troduced into the fame tube. The open end is then hermeti- cally Sealed, and the other end is plunged into boiling water. The phofphorus melts, and fixes itfelf upon the match. A line is drawn at one'third of the"length of the tube, with a flint, that it may be broken as occafion may require. The match is to be drawn out quickly, to enflame the phof- phorus. ,,./,',, The procefs of Mr. Lewis Peyla, to make the inflammable bou-des, confift in taking a glaSsfiibe, five inches long'and two lines wide, one end of which is fealed with the blow pipe. Small tapers of wax are prepared with three double threads of cot- ton twifted together. The extremity of the match or taper is half an inch long, and muft not be covered with wax. r A piece of lead is laid in a Saucer filled with water; and upon this' the phofphorus is cut, beneath the water, into frag- ments of the fize of a grain of millet. One of thefe grains is to be dried, and introduced into the tube of glafs ; after which the fortieth part of a "grain of very dry fulphur is to be added, that is to fav, half the weight of the phofphorus. One of the bougies is then taken, and its extremity dipped in very clear oil of wax. If too large a quantity rifes, it muft be dried with a cloth. , . . ■ The match is introduced into the tube with a turning or twitt- ing motion between the fingers. .... The bottom ofthe tube muft then be 'plunged in boiling wa- ter, to foften the phofphorus ; obferving to keep it no longer than three or four Seconds in the water. The other extremity of the tube is afterwards fealed. Thefe bougies muft be kept in a tin tube, to avoid the danger of inflammari. n. , 1. To form the phofphorick bottles, a glafs bottle is heated bv fixing it in a ladle full of fand, and two or three fmall pieces of phoSphorus are then introduced into it. A Small red hot iron wire is uSed to Stir the phofphorus about, and caufe it to adhere to the internal furface of the bottle, where it forms a reddifh coating. The heated wire is introduced repeatedly ; and when ail the phofphorus is thus diftributed within the bottle, it is left open for a quarter of an hour, and afterwards corked. When this is ufed, a corrfmon match tipped with Sulphur is introduced into the bottle, turned round and quickly drawn out. Trie 5^ Habitudes of Phofphorus. phoSphorus which fticks to the fulphur takes fire, and lights the match. The theory of this phenomenon depends on the circumftance that the phoSphorus is ftrongly dried, or half calcined, and needs only the contaa of air to fet it on fire. Phofphorus is foluble in oils, more eSpecially the volatile oils, which then become luminous. If this Solution be kept in a bot- tle, a phoSphorick flaSh, which emits a Small quantity of light, will be feen every time the bottle is opened. The oil of cloves is ufed in this operation. The combination of phofphorus and oil appears to exift naturally in the glow-worm, lampyris SpJen- dldula Linnaei. Forfter of Gottingen obServes, that the fhining matter of the glow-worm is liquid. If the glow-worm be crush- ed between the fingers, the phofphorefcence remamson the fin- ger. Henckel reports in the eighth differtation pf his Pyritolo- gia, that one of his friends, of a Sanguine temperament, after having danced much, perSpired to fuch a degree that he thought his life in danger. While he undreSfed, traces oS phofphorick flame were feen on his Shirt, which left yellow red Spots behind them, reSembling the refidue of burned phoSphorus : this light was long vifible. A phoSphorick gas may be extraaed from phofphorus, which takes fire by the mere contaa oS the air. Mr. Gengembre. has fhe'wn the method of extraaing it, by digefting alkalis upon it, (Memoir read to the academy at Pans the 3d of May, 1783); and at the fame time I Shewed that it might be extraaed by means of acids, which are decompoSed upon phoSphorus. I have likewiSe taken notice, in. my Memoir upon the decomposi- tion of the nitrick acid by phoSphorus, that when the acid is digefted upon it, a gas efcapes, which takes fire in the receiver, and has feveral times afforded me the appearance of SlaShes of lightning Striking through the cavity oS the veffels. But this phenomenon disappeared as foon as the vital air was. abSorb&d. It is to the disengagement oS a'gas of this nature that we may attribute the ignis fatui which plays about burying grounds, ari$ generally iri all places where animals are buried and purrefy. . It is to a Similar gas that we may reSer the inflammable air _ which conftantly burns in certain places, and upon the Surface of certain cold Springs. PhoSphorus is Sound in the three kingdoms. M^ Gahn found the phofphorick acid in lead. Siderite in a phofphorus of iron. The Seeds oS rocket, oS muftard, of garden creffes, and of wheat, treated by Mr. Margraaf, afforded him a fine phoSpfiorus. Mr. Meyer, of Settin has announced, in the Chemica] Annals of Crell for the year 1784, that the green refinous part of the leaves Decompofition of' Phofphorm. r g f ' o£ plants contains the phoSphorick acid. Mr. Pilatre du Roziet". renewed the opinion oS Rouelle in 1780, (Journal de Phyfique for November,) who confidered the phofphorick acid as anala- gous to that of mucilaginous bodies ; and he affirms that the diftil- lation of pyrophorus affords five or fix grains of phofphorus in the ounce. The phoSphorick acid exifts in urine, bones, horns, &c. M, Maret by treating twelve ounces oS beef by combuftion, obtained. three gros of tranfparent phoSphorick glaSs. M- Crell obtained, it from beef Suet and human fat; M. Hankwitz from excre- ments ; Leidenfroft from old cheefe ; Fontana from fifh's bones ; Bernaird from egg fhells, &t. Meffrs. Macquer and M. Struve found the phofphorick acid in the gaftrick juice. - The moft interefting combination of phofphorus is that which4 it forms with vital air. This is always the phofphorick acid ;. but the acid appears to be modified by the manner in which it! is made. Phofphorus unites with the oxigene—1. By deflagration, or. the rapid combuftion. 2. By the Slow combuftion. 3. In thd. hfcmid way, more efpecially by the decomposition of the nitrick acid. 1. If phofphorus be expofed to a dry heat of twenty-four de- grees, it takes fire, emits a white denfe fume, and leaves a red- diSh refidue, which powerfully attraas the humidity of the air, and becomes refolved into a liquor. This combuftion may be performed under glafs veflels in which cafe white flocks are de- pofited on the fides of the glafs, which refolve into a liquor by the contaa of mOift air, and form the phofphorick acid. Care is taken to introduce an additional quantity of vital air when the combuftion of the phofphorus has not been completed. M. Lavoifier has burned phofphorus, by the affiftance of a burning glafs, under a veffel plunged in mercury (Memoirs of the Royal Academy of Sciences, 1777.) Margraaf had obferved that air is abforbed in this operation. M. Morveau, in the year 1772,113d declared the Same Srom his own experiments ; and Fontana proved that phoSphorus abSorbs and vitiates air, like every other combuftible fubftance. Meff. Lavoifier and De la Place found that forty-five grains of phoS- phorus abforbed 65.62 of viral air. The acid obtained by this means is impure. It always con- tains phofphorus in folution, not Saturated with oxigene. 2. PhoSphorus is moft completely decompoSed by the Slow combuftion. For this purpoSe the neck oS a glafs funnel is in- Serted into a bottle, and fticks of phofphorus are difpoSed round in the funnel, fo as not to touch each oilier j a fmall piece of glafs tube being put into the neck, to prevent their falling $kl*\ Propertied of Phofphorick Add. throu'|H.v' A pa'peV' is "tied over the funnel.' Trie phofphorus ' is fldwljr decompofed; and, as it becomes converted into a fluid, it flows into the bottle, where it forms a liquid without fmell or colollfV This acid almoft alWays retains a fmall quantity of un- decc^npofed phofphorus, from which it may be cleared by digef- ting 4lcohol: upon it, which diffolves the phoSphorus without volatilizing the acid. One ounce oS phoSphorus produces in this manner three oun- ces of phoSphorick add. 3. The nitrick acid may be decompoSed by' digeftion upon phofphorus. The nitrous gas diffipated ; and the oxigene re- mains united to the phofphorus, with which it forms phofphor- ick'^cid. When the nitrick acid is very concentrated, the phof- phorus takes fire, and burns at its furface. I publifhed this proceSs, with all the circumftances of the operation, in 1780, the fame year in which the excellent Memoir of M. Lavoifier ' on the fame queftion was printed, and of which I had then nd knowledge. The water in which phofphorus is kept, contraas acidity in the cpurfe of time ; which Shews that the water itSelS is decom- pofed, and yields its oxigene to the phoSphorus. PhoSphorus precipitates Some metallick oxides from their So- lutions in the metallick State. It is obServed that acid is Sormed in this operation ; which proves that the oxigene quits the met- al to unite with the phoSphorus. The'phoSphorick acid s clear, inodorous, without being cor- rofive.-' It may be concentrated to drynefs. Crell having con- centrated it to drynefs, Sound its fpecifick gravity, compared' ' with water, to be as 5. 1. This acid is very fixed. If it* be concentrated In a mattrafs, the water is firft diffipated, a fmell of garlick is foon perceived, which arifes from a portion of- phofphorus, from which this acid is difficultly cleared : and vapours likewife rife. The li-. . qubr becomes turbid, affumes a milky appearance, and a pafty' confiftence ; and if the matter be put into a crucible, on hot coals, it boils confiderably. The vapour which iffues renders the" flame grfcen ; and the. mafs at laft becomes convened into a white tranfparent glaSs inSoluble in water. The phoSphorick acid has no aft'On on quartz. h diflblves clay with ebullition. It diffolves barytes ; and unites to clay with Singular facility, wifn which it forms a felt of Sparing Solubility^ The folution, wlferi well charged, lets fall, at the end1 of Sour-arid-twenty hours, cryftals in Small thin flattened needles, Several lines long, and obliquely truncated- at each end. The phoSphorick acid" Phofphorick Salts. Animal Subftances. n*i precipitates lime fromlime water, and, forms a true phofphate of lime very fim^ai" to the bafis of bones, and decompofable by the mineral acids like that fubftance. v The piiofpnorjck acid, faturated with potaSh, forms a very fo- luble Salt, which affords tetrahedral cryftals terminating in ^te- trahedral pyramids. This phoSphate is acid, Swells up on hot coals, and is difficult t.f fufion. Lime water decompofes it. Soda, combined with the phofphorick acid,.affords a fait of a tafte refembling that of the muriate of foda. This phofphate does nor-cryftallize, buf becomes converted into a gummy and deliquefcent mafs by evaporation. Mr. Sage affirms that phof- phate of Soda prepared with the acid of the flow* combuftion, forms a fait fufceptibleof cryftallization. • • Dr. George Pearfon has combined the phofphorick acid obtain- ed by nitrick acid, with Soda, and obtained, a neutral fait rin r rhomboids. This Salt, though Saturated, turns Syrup of violets green,lflff- flqrefces in the air, and has a Saline tafte reSembling that^of common Salt. It purges in the dole from, fix to eight drains, Without producing either naufea or griping, and has not. a d[fa- greeable tafte. The phoSphorick acid aas only on a Small number of metal- lick fubStafices. On this Subject the works of Meff. Margraaf, and De J*Vlorveau may be confodted. The phoSphorick 'acid has a very evident action on oils. ,X4jx- ed with an equal portion oS olive oil, it acquires a fawn colour .by mere agitation, which fubfifts even after the Separation. .This Shade increaSes iS the two fluids bedigefted togethef ; the acid becomes thick ; and the oil which floats, above becomes black and coaly, and emits a ftrong Smell. CHAPTER X. Concerning certain Subftances obtained from Animals for the ufe of Med- icine and the Arts. THERE is not perhaps any animal produa whofe virtues have not been celebrated by Some oS the phyficians.; and there are few animals which have not at Some time or other K been mentioned as contributing to the advantage oS medicine. Time however has happily condemned ro oblivion thoSe produaions which.ought never to have poffeffed celebrity ; and we fhall ac- cordingly 0" the preSent occafion, attend only to Such as experi- ence has'Shown to poffefs the virtues and powers attributed,to them. . 5^4 Caftoreum. We Shall not therefore treat of the lungs of the fox, the litter of the wolf, the feet ofthe elk, the jaws oS the carp, the nefts of the Swallow, the powder of the toad, the dung of the pea- cock, the heart of the viper, the fat of the badger, nor even that of the hanged malefaaor. Various quadrupeds, cetaceous animals, birds, and fifties, af- ford produces in which chemical and medical experience has as- certained very evident virtues. ARTICLE I. Concerning the Products afforded by Quadrupeds. Under this article we Shall treat of the produas moft in uSe which are extraaed from quadrupeds. Thefe are caftoreum, mufk, and hartShorn. i. Tbe name of Caftoreum is given to an unauous fluid con- tained in two pouches Situated in'the inguinal region of the male or female caftor. An accurate deScription of it may be feen in the Encyclopedic This very odorant fubftance is foft, and nearly fluid when recently extraaed from the animal ; but it dries in the courfe of time. It has an acrid bitter and naufe- ous tafte ; and its fmell is Strong, aromatick, and even ftink- ing. Alcohol diffolves a refin which colours it ; water extraas an abundant principle. By evaporation oS the water a Salt is ob- tained, the nature of which is little known. Caftoreum affords by diftillation a fmall quantity of volatile oil, ammoniack, Sec. The uSes oS caftor in the economy oS the animal are unknown. The ancients had the credulity to believe that the creature itSelf took it when its ftomach was weak. It is ufed in medicine as a powerSul antiSpaSmodick,in the,doSe of a few grains in Subftanee ; and it enters as a component part intoboloufes, extraas, Sec. It is advantageoufly joined with o- pium ; and its Spiritous tinaure is alSo preScribed in Suitable li- quids, in a doSe Srom twenty-Sour to thirty-fix drops. We See clearly from the little chemical information we pof- feSs reSpeaing this Subftanee, that it is a refin joined with a mu- cilage, and a Salt which facilitates the union of its principles. 2. fhe name of mufk is given to a perfume obtained from various animals. In 1726 an animal was received, under the name ofthe Mufk Animal, in the Royal Menagerie, which came from Africa and refembled the civit. Mr. Perrault has left a defcription of it. It was fupported fix years upon raw flefh. M. De la Peyronnie gave a very good deScription of it to the Academy of Sciences Sor the year 1731. • The Muft Animal. Hartfborn. $$$- The organ Which contained the mufk was Situated near the genital parts (it was a Semale.) At the aperture of the bag which contained the mufk the Smell was So ftrong, that M. De H Peyronnie could not inSpea it without inconvenience. This liquor is prepared by two glands, which tranfmit it into the common refervoir through a nuniber of fmall perforations. The other animal which affords mufk in the Eaft, is of the clafs of Squirrels. It is very common in ChineSe Tartary. It carries the mufk in a bag beneath the navel. This bag projea- ing outwards oS the fize of a pullet's egg, is formed of a mem- braneous and mufeular fubftance, provided with a fphinaer. Many glands are obfervable within, which feparate the humour. As foon as the bead is killed, this bladder is cut off and tied up : but its contents are adulterated with the tefticles, the blood, and other offals of the animal; for each creature affords no more than three or four gTos. Mufk muft be cho:en foft, unauous, and odorant; and ought to be confumed totally tipdnhot coals. The mufk of Tonquin, which is moft efteemed,4 is' contained in bags covered with brown hair ; but that Of Bengal is covered with white hair. Mufk contains nearly the fame' principles as caftoreum. The Smell of pure and unmixed mufk is too ftrong and oppreffive. It is rendered mild by mixture with other fubftances. It is lit- tle'ufed in medicine ; is a powerful antifpafmbdick in fome ca- Ses; but ought to be adminiftered with caution, becauSe it often ' excites nervous affeaions inftead oS calming them. The Smell of mufk predominates in certain animals. M. De : la Peyronnie' knew a man from whofe left arm-pit there was .. emitted fo ftrong a fmell of mufk during the fummer, that he was obliged to weaken it to avoid inconvenience. 3. Hartfhorn affords feveral produas which are much em- ployed in medicine. The preference is given to this horn be- cauSe it contains leSs earthy Salt than bones ; but all kinds of horn maybe uSed indiscriminately. Hartfhorn was formerly calcined with the greateft care, and uSed as a remedy againft alvine fluxes. The produas of hartfhorn which are moftly ufed at prefent, are thofe obtained by diftillation. An alkaline phlegm is firft obtained, which is called the Volatile Spirit of Hartfhorn. Next comes over a reddifh oil, more or lefs empyreumatick ; and a very'great quantity of carbonate of ammoniack, foiled and col- oured By the empyreumatick oil. The oil which colours the fait" may be difengaged by means of fpirit oS wine, which dif- fofves it.' The coaly refidue contains natrum, fulphate, and 4...C 586 Animal Oil of Dipple. Spermaceti.^ and phofphate of lime, from which phoSphorus may be obtained by the proceffes already deScribed. . The Spirit and the Salt obtained Srom hartlhorn are uSed in medicine as good antifpafmodicks. The oil duly reaificd Sorms the.animal oil of Dippel. As the Ivgheft virtues have been attributed to this fubftance, a thoufand methods have been attempted to purify it. ror» long time it was ufual to reaify it a great: number of times, m order to have it white and fluid. But Meffrs. Model and Baume have advifed taking only the firft portion which comes over, be- caufe this is the moft attenuated, and the whiteft. Rouelle ad- vifes diftillation with water ; and as the moft volatile part only arifes with the heat of boiling water, there is a certainty of hav- ing it very fine by this means. For my part, I diftil the em- pyreumatick oil with the earth of Murviel, which retains all the colouring part; and by this means I have it at once white and attenuated. This is odorant, and has all the properties ofthe volatile oils: but it turns fyrup of violets green, as Mr. Parmentier has ob- ferved ; which proves that it retains a fmall quantity of volatile alkali. ' This oil is ufed in dofes of a few drops in nervous affections, epilepfy, &c. It is ufed externally, by rubbing it on the fk.n, as a Sedative, and to remove obstructions; but the great virtues formerly attributed to it are not much credited at pref- ent. ARTICLE II. Concerning certain Products afforded by Fifhes. The oil of fifh, and Spermaceti, are the moft uSed among the produas pbtained Srom fifhes. Spermaceti is a concrete oil extraaed Srom the cacholot. The name of Sperma-ceti is very improper. Thefe animals are of a prodigious fize, and afford large quantities of this mat- ter. Plomet relates that in 1688 a Spanilh Ship took a whale whofe head afforded twenty-four barrels of brains, and the bo- dy ninety-fix barrels of fat. This fpermaceti is always mixed with a certain quantity of inconcrefcible oil, which is carefully removed. ,. „ • - Soermaceti burns with a very white flame. It is made into candles at Bayonne and at St. Jean de Luz. Thefe candles are of a white thining colour, become yellow in procefs of time, but not fo foon as wax and the denfe oils. If rit be diftilled on a naked fire, it does not afford an acid phlegm, but rifes totally, at the farne time that it affumes a red- difh tinge. Several repeated distillations deprive it of its natur- al confiftence. Component Parts of Eggs. C$7 The fulphurick acid diffolves it j and this folution is pre- cipitated like the oil of camphor.- The nitrick and muriatick acids have no aaion upon it. Cauftick alka'li diffolves fpermaceti, and forms a foap which gradually acquires folidity. Alcohol diflblves fpermaceti, by the affiftance of heat, but lets it fall as it cools. Ether likewife diffolves it. The fixed and volatile oils diffolve it by the affiftance of heat. This fubftance was formerly much ufed. It was given as an emollient, and foftening remedy; but at prefent it is almoft forfaken, and not without caufe; for it is heavy, infipid, and _, naufeous. The egg, the Scales, and the black fluid oSthe cuttle fifh, are ftill uSed in medicine. The eggs deterge the kidneys and excite urine and the cdurSes. The Scales and bones oS the cuttle-fifh are applied to nearly the Same uSes : they are likewiSe ufed as an aftringent; and enter into dentifrice powders, collyria, &c. The goldfmiths likewife ufe them to make their moulds for caft- ing fpoons, forks, toys, &c. becaufe its fpongy part eafily re- ceives the impreffion of metals. 1 he black humour of the cut- tle-fifh, which is found in a bag near the ccecum, and of which Mr. Le Cat has given a defcription, may be ufed inftead of ink. We read in the Satires of Perfius that tbe Romans ufed it as an ink ; and Cicero calls it Atramentum. It feems that the Chi- nefe ufe it as the bafis of their famous ink. " Sepia pifeis eft qui habet fuccum nigerrimum, inftar atramentl, quern Chinenies cum brodio orizse, vel alterius leguminis, infpiffant et formant, et in univerfum orbem tranfmittunt, fub nomine Atramenti Chinenfis" (Pauli Hermani Cynofura, t. i. p. 17, par. 2.) Piiny was of opinion that the black humour of the cuttle-fifh was its blood. Rondelet has proved that it is the bile. This is the flu- id the cuttle-fifh difgorges when in danger : a very fmall quan- tity is fufficient to blacken a large quantity of water. Calcined oyfler Shells are likewife ufed in medicine as an ab- forbent. The oil extraaed from fifh is of the greateft ufe in the arts. ARTICLE III. Concerning certain Products afforded by Birds. Moft of the birds are ufed at our table6 as a delicate food,but few afford any medical produas. The eagle ftones, to which fo much virtue had been attributed for facilitating labours, the plafters of fwallows nefts, and other fimilar fubftances, have all fallen into negfea, as the natural confequence of the obser- vation of matter of faa being Substituted in the place oS credu- 5&8 Analyfis of Cantharides. lity and fuperftition, The analyfis of eggs begins to be known. . They confift of four parts : an offeous covering, called the fhell i a membrane which covers the conftituent parts of the egg ; the white ; and the yolk, which occupies the centre. The fhell, like bones, contains a gelatinous principle, and the phofphate of lime. The white is ofthe fame nature as the ferum of blood. It renders fyrup of violets green, and contains uncombined chalk; heat coagulates it ; by diftillation it affords a phlegm which ea- fily putrefies ; it becomes dry like horn ; and carbonate of am- moniack, and empyreumatick oil, come over. A coal remains in the retort, which affords foda, and phofphate of lime. M. Deyeux has alfo obtained fulphur by full'mation. Acids and alcohol coagulate it. IS it be expoSed to the air in thin leaves, it dries, and becomes confiftent ; and it is on this property that the cuftom is found- ed of paffing the white of egg over the furface of paintings, to give them that brightnefs which is produced by varnilh, and al- fo to defend them from the air. The drying may be haftened by quick-lime ; and this mixture affords a lute of the greateft tenacity. The yolk of eggs likewife contains a lymphatick fubftance, mixed with a certain quantity oS mild oil, which on account of this mixture is foluble in water. It is this animal emulfion which is known in France by the name of lait depoulle. Yolk of egg expofed to the fire affumes a confiftence lefs hard than the white. If it be bruifed, it appears to have Scarcely any con- fiftence ; and if it be fubjcaed to the prefs, it gives out the oil it contains. This oil is very emollient, and is ufed externally as a liniment. There is the greateft analogy between the egg of animals and the feeds of vegetables ; fince both contain an oil rendered foluble in water by the admixture of a glutinous fub- ftance. The yolk of egg renders oils, and refins foluble ; and this fub- ftance Is accordingly much ufed for that purpofe. Calcined egg fhells is an abforbent.. White of egg is fuccefsfully uSed to clarify vegetable juices, whey, liquors, &c. It coagulates by heat ; and then rifes to the furface of thefe fluids, carrying with it all the impurities they contain. ARTICLE IV. Concerning certain Products afforded by Infects. Millepedes, cantharides, kermes, cochenille, and lac, are the pnly fubftances we Shall here treat of, becaufe thefe are not on- Analyfis of Cantharides. 58* Iy the moft ufed, but are likewife the beft known among the produas of infecls. i. Cantharides—The cantharides are fmall infeas with greenifh wings. They are very common in hot countries ; and are found on the leaves of the afh, the rofe tree, the poplar, the walnut tree, the privet, &c Cantharides in powder, applied to the epidermis, cauSe blist- ers, excite heat in the urine, ftrangury, thirft and fever. They produce the fame effea taken internally in a fmall dofe. We read in Pare that a courtezan, having prefented a ragout pow- dered with cantharides to a young man who Supped with her, this unfortuna/e ,perfon was attacked with a priapifim, and loSs ofbloodbythe anus, of which h- died. Boyle affirms that pains at the neck of the bladder have been produced by the handling of cantharides. We are indebted to Mr. Thouvenel for fome information re- fpeaing the conftituent principles oS theSe inSeas. Water ex- traas a very abundant principle, which colours it of a reddifh yellow, and alSo a yeilowifh oily principle. Ether takes up a green very acrid oil, in which the virtue of the cantharides moft eminently refides. So that an ounce oS cantharides affords— Reddifh yellow bitter extraa Yellow oily matter Green oily fubftance, analogous to wax Parenchyma, inSoluble in water and alcohol To Sorm a tinaure which unites all the properties of can- tharides, a mixture muft be made of equal parts of water and of alcohol, and the infeas digefted in it. If this tinaure be dif- tilled, the fpirit which comes over retains the fmell of canthar- ides. If fpirit of wine alone be ufed, it takes up merely the cauftick part : hence it appears that the virtue of thefe infeas may be increafed or diminifhed according to the exigence of the cafe. The tinaure of cantharides may be ufed with fuccefs exter- nally, in the dofe of two gros, four gros, one or even two ounc- es, in rheumatick pains, feiatica, wandering gout, &c. It heats the parts ; accelerates the circulation ; excites evacuations by perfpiration, urine or Stool, according to the parts to which it is applied. gros. grains. 3 o O 12 o 6o 4 o 8 o 59° Production of Ccchinelle. Mr. Thouvenel tried upon himfelf the effea of the green waxy matter. When applied on the Skin in the dofe of nine grains, it raifed a blifter full of ferofity. 2. The wood lice, millepedes, aSelli, porcelli.—This infea is uSually Sound in moift places, under ftones, or beneath the bark oS old trees. It avoids the light, and endeavours to conceal it- felf when discovered. When it is touched, it rolls up in the form of a globe. This infea is uSed in medicine as an incifive, aperitive and alterative remedy. It is preScribed either pounded- alive and put into a proper liquid, or dried and pulverized, in which laft form they enter into extraas, pills, &c. The mille- pedes are given in the doSe of Sourteen, fiSteen,and twenty grains or more, according to the exigency of the cafe. P.-Jr. Thouve- nel has given us fome information concerning the conftituent principles oS theSe inSeas. He obtained by diftillation an infip- id or alkaline phlegm ; the refidue afforded an extraaive mat- ter, an oily or waxy fubftance Soluble in Spirit oS wine only, and marine Salt with an earthy and an alkaline baSe. 3. Cochenille.—Cochenille is a Subftanee uSed in dying Scar- let and purple. It is met with in commerce in the Sorm of fmall grains of a Singular figure, moftly convex, with little grooves on one fide, and concave on the other. The colour of good cochenille is grey mixed with reddiSh and white. It is at prefent well determined that it is an infect. Simple infpeafon with a magnifier Sufficiently proves this : and the wings and feet of this infect may be developed by expofing it to the vapour of boiling water, or by digefting it with vinegar. The coche- nille is colfeaed in Mexico, upon plants to which the name of Indian Fig, Raquette Nopal, are given. Thefe plants bear fruits which refemble our figs; tinge the urine of thofe who eat them and probably communicate to the cochenille the property which makes it ufeful to the dyer. The Indians of Mexico cultivate the nopal near their habitations, and fow as it were the infea which affords the cochenille. They make fmall nefts of mofs or fine herbs, put twelve or fourteen cochenilles into each nelt, place three or four of thefe nefts on each leaf of the nopal, and fallen them there by the prickles of the plant; in the courfe of a few days, thoufands of fmall infeas iffue out and fix thenj- felyes upon the parts ofthe leaf which are bcft Sheltered, and af- ford the moft nourifhment. The cochenilles are collected fev- eral times in the courfe of the year ; and are deprived of life by Scalding them, or by putting them into an oven ; after which rhey are dried in the Sun. Two kinds oS cochenille are diftin- guifhed : the one which is produced without culture, and is called Sylveftre ; and the other cultivated, which is called Mef- Preparations of Kermes. * 592 Acid of Silk Worms. Mr. Geoffroy has proved,-in a Memoir inferred among thofe ©f the Academy for the year 1714, that this muft have been a kind of comb, approaching to the honeycomb of bees, the cells of which are formed of a fubftance analogous to wax.* The colouring part of lac may be taken up by water, which, when evaporated, leaves the colouring principle difengaged. It is the fine lake ufed for dying. Lake is imitated by extraaing the colouring principle of certain plants by well known proc- effes. CHAPTER XI. Concerning fome other Acids extract ed from the Animal Kingdom. INDEPENDENT of the acids afforded by the various parts •f the human body, which have been feparately examined by us we find acids in moft infeas. Lifter points out one which may be extracted from millepedes (Collect. Acad. torn. ii. p. 303). Mr. Bonnet has obferved that the fluid ejeaed by the great fork- ed tail caterpillar of the willow, was a true acid, and even very aaive (Savans Etrangers, torn. ii. p. 276): Bergmann compares it to the moft concentrated vinegar. The abbe Boiffier de Sau- vageshas remarked, that in that illnefs oS the filk worm, which is called muScardin, the humour ofthe worm is acid. Mr. ChauSfier oS Dijon obtained an acid from graSs-hoppers, from the May-bug, from the iampyris, and feveral other infeas, by digefting them in alcohol. The fame chemift has made an in- terefting courfe of experiments on the acid of the filk worm. He gives two methods of extraaing it. The firft confifts in bruifing the chryfalides, and Straining them through a cloth. The fluid which paffes is ftrongly acid ; but the acid is weakened by various foreign fubftances, of which it may be cleared by digeS- tion in Spirit of wine. The fluid which paffes the filtre after this digeftion, is of a fine orange colour. More fpirit of wine ,is to be poured upon it. At every addition of fpirit a light whitifh precipitate is formed ; a id the additions of fpirit are to be continued until no more precipitate appears. Inftead of bruifing the chryfalides they may be infufed in Spirit of wine, which diffolves all the acid ; and as this acid is lefs vol-. atile than the fpirit, this laft may be evaporated, and the refidue * For a defcription and drawing of the infect which affords the lac, eonfult Keir in thePhilof. Tranf. vol. Ixxi. p. 374 ; alfo Saunders, in the fame work, vol. lxxix for r.he method of purifying the lac ; or a fhort abridgment of both, in Nichoifon's Firft Principles of Chemiftry, p. 400. T. Acid of Ants. 593 filtered. By thefe precautions the acid may be cleared of its fpirit of wine, and of the mucous matter which was diffolved, but remains on the filtre. Mr. Chauffier has proved that this acid exifts in all the ftates of the filk worm, even in the eggs ; but that in the egg and in the worm it does not exift in a difengaged ftate, but combined with a gummy glutinous fubftance. The acid of infeas which is beft known, and upon which moft has been wtitten, is the acid oSants, or the Sormick acid. This acid is So Sar in a diSengaged ftate, that the tranSpiration of thefe animals, and their Simple contaa without any alteration, proves its exiftence. The authors of the fifteenth century had obferved, that the flower of chickory thrown into an ant hill becomes as red as blood.-—See Langham, Hieronimus Tragus, John Bauhin. Samuel Fifher is the firft who difcovered the acid of ants, in a courfe of experiments for the analyfis of animal fubftances by diftillation. He even tried its aaion on lead and iron ; and communicated his obfervations to J. Vray, who inferted them in the Philofophical Tranfaaions in the year 1670. But it was the celebrated Margraaf who more particularly examined the properties of this acid in 1749. He combined it with many fubftances, and concluded that it greatly refembled the acetous acid. In 1777 this fubjea was again refumed by Meffrs. Ar- vidffon and Oerhn ; and treated in a manner which leaves lit- tle to be defired, in their differtation publifhed at Leipfic. The ant which affords the greateft quantity of acid, is the large red ant which is found in dry and elevated places. The months of June and July are moft favourable for the ex- traaion of this acid ; they are then fo penetrated with it, that their fimple paffing over blue paper is fufficient to turn it red. Two methods may be ufed to obtain this acid : diftillation and lixiviation. To extraa the acid by diftillation, the ants are firft dried by a gentle heat, and put into a retort, to which a receiver is adap- ted, and the fire is raiSed by degrees. When all the acid is come over, it is Sound in the receiver mixed with a Small quan- tity oS empyreumatick oil, which floats upon it, and may be fep- rated by a funnel. Meffrs. Arvidffon and Oerhn obtained, in this manner, from each pound of ants Seven ounces and a halS of an acid whoSe Specifick gravity, at the temperature of fifteen de- grees, was to that of water, as 1.0075 to i-oooo In the proceSs of lixiviation, the ants are wafhed in cold wa- ter ; and boiling water is afterwards poured over them, which is filtered when cold. More boiling water is poured over the ref- 4-..D 473 Alkaline Gas I28 Aloes 449 Alum 3©3 Alumine 180 Amalgam 33° Amber 5" Amianthus »"J Animal Subftances 54i Antimony „ »95 4...F Page Apparatus Pneumatick 90 Aqua regia 168 Aibor Dianae 38a Arqhil 481 Aroma 497 Arfenick 28a Ammoniack 127 ^al 165 214 Afbeftos ASphaltes 510 Affa Fcetida 448 Attraction, 5 1 et feq. Aurum Mufivum 33o Azure »99 B. Balances 5s Balloon air 94 Balfams 444 Bark of Vegetables 4*i Barytes 178 Bafaltes 24! Benzoin 445 Beryl %29 Bile 557 Bifmuth 39% Bleaching I6i Blende 306 Blood 105,551 Borate of Ammoniack 175 ----of Potafh 17I ----of Soda ibid Borax and its acids et feq. 169 Brandy 5*6 Brewing S*S Bronze 367 Butter 55° C. Cacholong *37 Calcedony *37 Calorick 7* Camphor 438 Cantharides 588 Caoutchouc 449 INDEX, Carbone Carbonate of ammoniack --------of Potafh -------- of Soda --------of Lime Carnelian Caffava Caftoreum Cat's Eye Charcoal Cheefe Chemiftry Chryfolite Chryfoprafe Cinnabar Clay Cobalt Copper Cream Crucibles Cryftal Cryftallization j8 et feq. D. Diamond Digeftion Diftilling Dying, arts of Eagle ftone Eaith Earth, Calcareous ——- Ponderous ----Magnefian ----Aluminous ----Siliceous Egg Elaftick Gum Elements Emerald Ether Ethiops Martial Evaporation Fat Fayence Fecul.i Feld Spar Fermentation Fire Flefh Flints Fluate of Lime uor Spar Page 87 139 138 139 182 238 455 584 237 56, 502 550 43 229 244 377 50 228 S58 550 48 23° Fulminating Silver Gold Furnaces Fufible Spar 258 543 47 475 G. Galena Garnets Gafes Gaftrick Juice ' Geology Girafol Glafs Gluten, Vegetable Glue Gold TJums Gum GuttJE Gun-powder Gypfum H. Heat Hematites Hepatick Stone Honey Horn-ftone Hyacinth Hydrogenous Gas Hydrophanes 338 W5 178. 179 Jafper 180 Jelly ibid Jet 181 Indigo 587 ; Iron 449 Ifinglafs 7° I 228 j M° Kaolin ?7° Kermes 46 r. K. 554 218 4'.] 245 5*J> 535 71, et feq. 564 235 194 ibid L. Labdanum Laboratory Lac_ Lapis Lazuli Lapis Infernalis Lava r_,ead Light Lime Liquorice « Page 39° 44, ct Seq. I94 316 226 90 544 261 *37 242 457 562 3«4 426 448 154 191 72, et. Seq. 210 ibid 486 222 227 91 238 238 561 517 478 33i 563 219 591 444 43 591 245 381. 241 8a,453 178, 188 505 INDEX. Lithology Luna Cornea Lutes M. Magnefia Magnefian Salts Magnet Manganefe Manna Marble Maftick Mecca, Balfam of Mercury Mercurius Dulcis Metals Mica Milk Mines Molybdena Montgolfier Mortar Mountain Cork Mucilage Muriate of Ammoniack ■ of Potafh ■ ■ ■ of Soda ------of Lime Mufk N. Naphtha Nickel Nitrate of Ammoniack ------of Potafh ------of Soda ------of Lime Nitrogene Gas Nitro-muriatick Acid Nitrous Gas O. Oculus Mundi Oils Olibanum Opal Opium Orpiment Oxigenous Gas Oxides Perfumes Petroleum. Page 175, et feq. 382 49 180 201 334 31c 49* 185 443 44I 368 375 270 220 545 »73 404 94 190 214 425 105 i6z ibid 197 584 509 291 156 15* 155 196 108 167 141 238 42- 449 236 493 284 96,495 133 498 509 Petrofilex Pewter Phofphate of Lime, various Phofphorick Glafs Phofphorus Pit Coal Pitch Flatter Stone Platina Plumbago Pollen Ponderous Earth Porcelain Porphyry Pottery Pot Stone Powder, Fulminating Precipitate Pruffian Blue Putrefaction ^ pyrites Pyrometer of Wedgwood Quartz Realgar Receivers Refins Refpiration Retorts Ruby Sago Sandarach Sal Ammoniack Salt, common Salt Petre Sapphire Scammong Schorles Selenite Serpentine Serum Siderite Silex / Silver Size Slate Smalt Soap Soap Stone 0^ R. Page 235 3*9 198 576 574 £°7 44* 191 393 339 484 179 219 *55 216 213 *5S 56 339 *7>595 95 75 334 *8* 48 44 r lot 47 226 455 443 165 162 163 230 448 240 191 213 SS3 339 181 378 563 222 *32 433 21* INDEX. Soil Solution Soup Spar, Ponderous Spermaceti Starch Steatites Steel Stone, ofthe Bladder Sublimate, Corrofive Sublimation Sugar Sulphate of Ammoniack i-----of Potafh i------of Soda .....of Lime Sulphur Swine Stone Talc Tartar Tin Tinning of Copper Topaz Tourmalin Trapp Trompe Tungften Turnfole Page 551 63 j6i 198 586 457 212 337 57» 374 46 459 »45 144 ibid 191 84*140 909 2X2 533 3*4 367 227 »39 244 278 398 IJO V. Ultramarine Urine Varnifh Vegetables Vermilion Veffels, chem. et feq. Vinegar Violets, Syrup of Vital Air Volcanick Products Volcanos W. Water, its compofition Waters, Mineral Wax Wolfram Wood Woulfe, his apparatus Zaffire Zeolite Zinc Page *55 566 45 * 409 377 44 535 IJI 96 241 51* III, 418 60i 485 401 4L? 5<>j 289 22j