-'?:.*&• - -vi--/:-* '"*■■». r . ■' "^'V . ' 'Tig** ;„' v:« .•>-''.4^'' . ' "•» ■■-«■■ rer*: tfl to-*1' !#»■ fr" *)*\ 'fc -": 0'- uQ^JZQ^u:T.DT)Q®Q®Zjd, in Lewis's Commerce of Arts, v. *.ere this subject is well treated, that the English have called this machine by any appro- priated name. T. PROPERTIES OF METALS. 11 When the mineral is once cleared of its gangue, its mi- neralizer, and all other foreign matter, it constitutes what is called a metal or regulus. Every fact appears to prove that metals are simple sub- stances ; the various alterations to which they are subject- ed, being combinations of the metal itself with other sub- stances. None of these operations either disengage or se- parate any constituent part of the metal itself, as we shall see. Every metal is fused at a certain degree of heat, more or less intense; and in this situation their surface is convex. Messrs. Macquer and Lavoisier having exposed gold to the focus of the lens of Tschimhausen, observed that this metal exhaled in fumes, without being decomposed; as was proved by collecting it unaltered upon presenting a plate of silver, which became gilt. Silver is volatilized in the same manner without decomposition. Metals fused, and cooled slowly, exhibit crystalliza- tions of considerable regularity. The abbe Mongez, and Mr. Brogniart, have succeeded in crystallizing most of them, by varying the process used by the celebrated Houlle in the crystallization of sulphur. Most metals kept in a state of fusion lose their metal- lic brilliancy^ and become converted into an opaque pow- der called Oxide, or Metallic Calx. The oxides, when urged by a stronger heat, are reduced into a vitriforra substance, known by the name of Metallic Glass. Metals acquire weight in their transition to the state of oxide. This circumstance has led several adepts into er- ror, who imagined they had increased the weight of the metal. Geber observes, " Ubi vel minimum augmenti metal- lici inveneris, ibi te dicimns esse ante fores philosopho- rum."—" Et sane conveniens judicium est," adds Becher; " id enim per quod corpus homogeneum augmentum ca- pit, id ipsum est quod pro principio istius corporis haberi potest."—Phys. Subt. Stahl pretended that the calcination of metals arose from the disengagement of phlogiston; and he considered their calces as an earth, or metallic basis. Boyle affirmed that the increase of weight in calcined metals was owing to the combination of the matter of fire; 12 PROPERTIES OF METALS. and Boerhaave ventured to attribute it to the surrounding bodies, which deposited themselves upon the metal. Of all the hypotheses which have been formed upon this sub- ject, that of Stahl has met with the greatest number of supporters : and the blind zeal of his followers has car- ried them so far as even to disguise an unanswerable ob- jection ; namely, that it can never be explained how me- tals, by the loss of one principle, at the same time that they do not acquire another, can become heavier. The reduction of the oxides or metallic calces, without any addition of the charcoal, cannot be explained on this hy- potlu sis. It must be confessed that all chemists were not of this way of thinking: and we find in the writings of Jean R< y, a Physician of Perigord, that he, in the year 163Q,- attributed the increase of weight in calcined metals to the mbmation of air with the metal. He affirms that agU lation facilitates this combination in no other manner than w-.ter renders the sand heavy which is thrown and agi- taJ'-d in that fluid. He reasons like a chemist of considerable skill, to prove that tlic increase of weight cannot be carried beyond a point of saturation; and he concludes his observations in these words : Le travail a He mien ; le profit en soit ate lecteur, et a Dieu seul la gloire—" Mine has been the labour; let the reader enjoy the advantage, and to God alone be the glory."* All these several sketches were never formed into a connected system ; and this doctrine was even completely* unknown, when Mr. Lavoisier proved to us that the cal-- cination of metals was owing merely to the fixation of oxigenous gas, and their reduction to the disengagement of this gas, effected by simple heat, or by its combina- tion with various bases in such instances wherein its ad- hesion to the metal is too strong-to be overcome by mere heat. The proofs upon which this celebrated che- mist has established his opinion, are the following facts. * This is the same Jean Rey, who, being under the necessity of contradicting his friend Libavius on the theory of the calcination of metals, exclaims—' () Truth, how dear art thou to me! since it is in thy power to make me enter into a contest with so dear a friend:" ■. Properties of metals. 13 1. Metals are not oxided either in a vacuum, or in air which contains no part of oxigenous gas. The Count Morozzo, Priestley, Lametherie, and Pictet appear to have oxided lead, tin, and mercufy in the carbonic acid. See the Memoir of Mr. Sennebier, Journal de Physique, Fevrier 1787.—But this pretended oxide is nothing but a metallic carbonate, or the combination of a metal with an acid, which is very far from calcination or oxidation. 2. Metals inclosed under a glass, and properly heated, are oxided only by absorbing the oxigenous gas contained in the mass of air which is insulated; and when this ab- sorption is ended, it is impossible to carry the oxidation any further. 3. Metals oxided in an atmosphere of oxigenous gas absorb it to the last drop. 4. Such oxided metals as are capable of being reduced in closed vessels, give out, on their return to the metallic state, the same quantity of oxigenous gas as they had be- fore absorbed. This doctrine appears to me to be established on the most complete series of proofs which can be desired in matters capable of demonstration. The concurrence of air and of humidity singularly assists the alteration of metals. The water is decomposed in this process, and its hydrogene is dissipated, while its oxigene combines with the metal. This is doubtless the theory of such oxidations as are effected beneath the surface of vva^ ter; and when we find oxides, or metallic calces, in the bowels of the earth, defended from the contact of air, the facts ought to be referred only to the decomposition of water, or of acids which have oxigene for their base. Hence it follows that the alteration of a metal will be the more speedy—1. In proportion as the affinity of the metal to oxigenous gas is stronger. 2. As the quantity of oxigenous gas is greater. 3. As the air is more humid, &c, Metals decompose certain substances in order to unite with their oxigene, and by that means to pass to the state of oxide. This is observable when the nitric acid is di- gested upon certain metals. Metallic substances being considerably numerous, it is necessary to class them, that we may bring together such as possess similar properties, and separate others which differ from them. 14 Concerning arsenic. Ductility serves as a leading character. Metals may be distinguished into such as are ductile, and such as do not possess this property. The name of Metal has been pe- culiarly applied to the former, and that of Semi-metal to the latter kind. Among the metals there are some which are change- able by exposure to air, while others are not sensibly altered in the'same situation. This difference has caused a sub- division of the metals into perfect and imperfect metals. We shall begin by treating of the semi-metals, because for the most part they approach to the saline or stony sub- stances in their qualities; and we shall conclude with the perfect metals, because they possess the metallic qualities in an higher degree. CHAPTER I. Concerning Arsenic. THE substance which is sold in commerce under the name of arsenic, is a metallic oxide of a glittering whiteness, sometimes of a vitreous appearance; exciting. an impression of an acrid taste on the tongue; volatile when exposed to fire, in which situation it .rises in the form of a white fume, with a very evident smell of garlic. Although arsenic is most commonly met with under this form, it may be reduced to the metallic state by treat- ing it with oils, soaps, or charcoal in closed vessels. The celebrated Becher was perfectly acquainted with this pro- cess.—" Si oleum, vel quodcunque pingue, arsenico mis- ceas, et per retortam distilles urgenti igne, sublimabitur in collum arsenicum, insignitur antimonii instar metalliza- tum."—The arsenic which sublimes is of a brilliant grey colour, resembling steel, but it speedily becomes black in the air: it forms crystals, which Mr. De Lisle considers as aluminiform octahedrons. Arsenic is sometimes found native; and it is met with in stalactites, or in protuberant depositions formed of layers more or less distinct and concentric, which are separable PROPERTIES OF ARSENIC. 15 from each other like the coats of an onion, or the laminae of shells, from which it has obtained the name of testace- ous arsenic. In other instances the masses are formed of very small scales; which renders the surface of the speci- men sometimes granulated, and sometimes full of small cavities: it is then called scaly arsenic. Arsenic is also found in friable masses, possessing scarcely any consist- ence. In these various forms we receive it from Bohe- mia, Hungary, Saxony, Saint Marie aux Mines, &c. Arsenic is volatilized by an heat of about 144 degrees of Reaumur. In order to set fire to this metal, it must be thrown into a crucible strongly ignited: and then it exhi- bits a blue flame, and rises in the form of a white oxide. If it be sublimed by a gentle heat, it crystallizes in tri- hedral pyramids, or in octahedrons. Arsenic is not soluble in water. Its specific gravity is 57633, according to Brisson. Its fracture resembles that of steel, but it easily tarnishes. Arsenic appears to exist in the metallic state in its com- binations with cobalt in the testaceous cobalt ore, or with iron in mispickel, according to the observation of Berg- mann. Arsenic unites by fusion with most of the metals; but those which were ductile before this addition, become brittle afterwards. Those which are of difficult fusion alone flow more easily by heat with the addition of arsenic, and those which are very fusible become refractory by the same addition. The yellow or red metals become white with this alloy. Arsenic is often combined with metals in various ores, and is disengaged from them by calcination. In various mine works, long winding chimneys are constructed, through which the arsenical vapours pass, and in which they attach themselves. The crust which is formed in process of time against the internal surface of these chim- neys is taken away, and is the substance met with in com- merce under the name of arsenic. The cobalt ores of Saxony, which are torrefied to separate this semi-metal, afford almost the whole of what is sold. This oxide of ar- , senic is sometimes native, and has been found in Saxony and Bohemia. It is very abundant in such places as are situated in the vicinity of subterranean fires, such as the 16 REALGAR. ORPIMENT*. Solfatara. It is often found crystallized in octahedrons, according to Mr. Sage. The oxide is less volatile than the metal itself; and, as we have before observed, it emits a very evident smell of garlic. If it be sublimed by a strong fire in closed ves- sels, it becomes transparent like glass; but its surface is soon rendered opaque again by exposure to air. It is not rare to find arsenical glass in the arsenic of commerce: it is yellowish, and soon loses its transparency by exposure to air. This glass is sometimes found native in the cobalt mines, and among volcanic products. Eighty parts of distilled water, at the temperature of twelve degrees, are required to dissolve one part of the oxide of arsenic; but fifteen are sufficient at the boiling heat. One part of arsenic is soluble in between seventy and eighty parts of alcohol at the boiling heat.* The oxide of arsenic partakes therefore of the proper- ties of saline substances, and diners from the other metal- lic oxides—1. Because it is perfectly soluble in water. 2. Because the other metallic oxides are without smell, and fixed in the fire. 3. Because those oxides do not contract any union with metals. On the other hand it resembles the metallic oxides__1. In becoming converted into a metallic glass by a strong heat. 2. In forming an opaque insoluble substance, pos- sessing the metallic brilliancy when deprived of oxigene. The oxide of arsenic is capable of combining with sul- phur; and the result is either orpiment or realgar, accord- ing to the manner of operating. Most chemists have a notion that the realgar contains more sulphur than the orpiment; and they have prescribed different proportions to form these two substances. But it has been proved by Mr. Bucquet, that this difference of colour arises only from the manner of applying the fire; nothing more being necessary to convert orpiment into re- algar, than the exposing it to a strong heat: and with the same mixture we may at pleasure obtain either of these products, according to the manner of applying the heat. * If arsenic in its pure metallic state, be kept covered with alko. hoi, it will preserve its metallic brilliancy.-.^. Ed. OXIDE OF ARSENIC 1" Orpiment and realgar are found native in certain places. Linnjeus, Walierius, Bergmann, and Cronstedt have de- scribed them.* Crystals of realgar are found in Solfatara near Naples, according to Ferber; in the mines of Nagyag in Transyl- vania (see Forster's Catalogue;) in the mines of Felsoban- ya in Upper Hungary; in those of Joachimstal in Bohe- mia, and of Marienburg in Saxony. Realgar is common in China; it is made into vases, pa- gods, and other ornamental works. The Indians make use of these vessels to procure a purgative medicine: for this purpose they leave vinegar or lemon juice for several hours in the vessel, and afterwards drink it. Realgar is commonly found in the waters of vvolcan6s, I have almost always observed it in compressed hexahe- dr:;l prisms, terminating in twro tetrahedral summits. Orpiment is less scarce than the realgar. It almost al- ways accompanies this substance; but the orpiment of commerce comes to us from various countries up the Le- vant, in irregular masses, solid or lamellated, and of a beau- tiful orange yellow. The Baron de Born informs us that it is met with, in polyhedral crystals, in a blueish clay near Newsol in Hungary. Lime and the alkalis decompose these two substances, and disengage the oxide of arsenic. The acids and the alkalis exhibit interesting phenome- na with arsenic. The sulphuric acid, when boiled on the oxide of arse- nic, attacks and dissolves it; but this oxide is precipi- tated by cooling. If the whole of the acid be dissipated by a strong heat, the arsenical acid remains behind. The nitric acid, assisted by heat, dissolve the oxides of arsenic, and forms a deliquescent salt, of which we shall presently treat. The muriatic acid attacks arsenic very feebly. Messrs. Bayen and Charlard found its action very weak whether heated or cooled. * A specimen of the sulphuret of arsenic, weighing about four ounces, was found about two miles from Philadelphia, in digging a cellar.— dm. Ed. Vol. II. C 18 SUBLIMED MURIATE OF ARSENIC. In order to form the sublimed muriate of arsenic, or butter of arsenic, equal parts of orpiment and corrosive sublimate of mercury are mixed together. The mixture is distilled by a gentle heat; and the receiver is found to contain a blackish corrosive liquor, which forms the sub- limed muriate of arsenic. Cinnabar comes over if the heat be increased, according to the observation of Mr. If pure potash be boiled on the oxide of arsenic, the alkali becomes brown, gradually thickens, and at last forms a hard brittle mass. This arsenical salt of Mr. Macquer is deliquescent. It is soluble in water, which lets fall brown flocks. It is decomposed by fire, and the arsenic escapes. Acids deprive it of its alkali, &c.* Soda exhibits phenomena nearly similar with this ox- ide ; and Mr. Macquer even affirms that he obtained this salt in crystals. I have proved that ammoniac dissolves the oxide of arsenic by heat; and I have several times obtained cry- stals of arsenic by spontaneous evaporation. I am even of opinion that the alkali is decomposed in these circum- stances, that the nitrogene is dissipated, while the hydro- gene unites with the oxigene of the oxide, and forms wrater. The oxide of arsenic hastens the vitrification of all the earths; but the glasses into which it enters as a compo- nent part, have the property of easily becoming tarnished.' Equal parts of nitre and oxide of arsenic, distilled in a retort, afford a very red and almost incoercible nitric acid. Stahl and Kunckel obtained it by a process nearly * Fowler's solution of arsenic is prepared in the following manner: Take white arsenic in fine powder and potash, of each 64 grains. Boil them in half a pint of water until the arsenic is entirely dis- solved. Then add, when the mixture has grown cold, another half a pint of water, and half an ounce measure of lavender compound. The dose of this medicine for an adult is ten drops, two or three times every day. It is used in intermitting fevers, in rheumatism., in periodical headaches, and in cutaneous eruptions. Dr. Darwin prefers a saturated solution of arsenic, which may be made in an oil flask or tin saucepan. He supposes it acts by stimulating the stomach into strong action, and thus by the associ- ation of this viscus, with the heart and arteries, prevents the torpor of any part of the sanguiferous system.—Am. lid. ACID OF ARSENIC. 19 similar. Macquer having resumed this work, carefully examined the residue in die retort, and found that it was a salt soluble in water, capable of crystallizing in tetra- hedral prisms terminated by four-sided pyramids, unalter- able in the air, fusible by a moderate heat, but without becoming alkalized. Mr. Macquer called it the neutral arsenical salt: he supposed that no acid could decompose it. But Mr. Pelletier proved that the sulphuric, when distilled with it, disengaged its acid. The arseniate of soda differs litde from the arse- niate of potash. Mr. Pelletier obtained this salt crystal- lized in hexahedral prisms, terminated by planes perpen- dicular to their axes. By these several experiments, Mr. Macquer had shewn that arsenic answered the purpose of ^an acid in these com- binations. There remained only one step therefore to be made, to prove that it was really metamorphosed into an acid in these several operations: and it is to the celebrated Scheele that we are indebted for this discover}'. His ca- pital experiments upon manganese naturally led him to it. He has given us two processes to obtain this arsenical acid; the first by means of the oxigenated muriatic acid, and the other by the nitric acid. These acids are distil- led from the oxide of arsenic : the muriatic acid aban- dons its oxigene to the oxide of arsenic, and resumes the characters of the ordinary muriatic acid. The nitric acid is itself decomposed; and one of its principles is dissi- pated, while the other is fixed and combines with the ar- senical oxide. This acid is at present obtained by distilling six parts of nitric acid from one of oxide of arsenic. Mr. Pelletier likewise proposes to decompose the ni- trate of ammoniac by the oxide of arsenic. The residue in the retort is the arseniate of ammoniac, from which the alkali may be driven by a fire long kept up. The re- sidue is a vitreous mass, strongly attracting humidity, and falling into deliquium. It is the pure arsenical acid. Mr. Pelletier has likewise decomposed the neutral ar- senical salt, by mixing it with half a part of oil of vitriol, and urging the fire to such a degree as to ignite the ves- sels. The residue at the bottom of the retort is a white mass, which attracts humidity, and is the arsenical acid. 20 ACID OF APvSENIC A white powder is observable, which is found to be the sulphate of potash or of soda, accordingly as the arseni- cal salt has soda or potash for its basis. From the various processes made use of to form the arsenical acid, it is evident that this substance is nothing but the arsenical oxide, saturated with the oxigene which it takes from the various bodies digested upon it. The nitric acid, or the nitrates used for this purpose, are de- composed ; the nitrous gas passes over very abundantly, and the oxigene remains mixed and united with the oxide of arsenic. This acid possesses the concrete form ; but it attracts the humidity of the air, and becomes resolved into a fluid. It is fixed in the fire; but if it be heated in contact with a coal}' substance, it is decomposed, and the oxide exhales in the form of fumes. It is reduced into arsenic, according to Mr. Pelletier, by passing hydrogenous gas through it. At the temperature of twelve degrees of the thermo- meter of Reaumur, this acid requires only two-thirds of its weight of water to dissolve it; whereas one part of the oxide of arsenic requires twenty-four of water to dissolve it at the same temperature. This acid, when dissolved in water may be again con- centrated, and carried to the state of a transparent glass without any alteration; for it is not by this treatment de- prived of its- power of attracting humidity from the air. When it is in this state of concentration, it acts strongly on the crucible, and dissolves the alumine, according to Mr. Berthollet's experiments. The arsenical acid, saturated with ammoniac, and duly evaporated, -forms a salt crystallized in rhomboides"; which, when urged by heat, loses its water of crystalli- zation, next its. alkali, and is resolved into a vitreous mass. Baiytes and magnesia appear likewise to have a stronger affinity with this acid than the alkalis, according to BerV- mann. Lime decomposes the neutral salts with base of alkali, according to the experiments of the same chemist Arsenic is used by the dyers : it is likewise used as a flux in glass-houses, and in docimastic works ; it also en tcrs as a component part into some glazes. Orpiment and COUXTERPOISON AGAINST ARSENIC. 21 realgar are very much used by painters; but arsenic is one of those productions whose advantages are not suffi- cient to compensate for its bad effects. This metal, which is very abundant, and very frequently met with in mines, causes the destruction of a number of workmen who explore them : being very volatile, it forms a dust which affects''and destroys the lungs; and the unhappy miners, after a languishing life of a few years, all perish, sooner or later. The property which it possesses of be- ing soluble in water, multiplies and facilitates its destruct- ive power; and it ought to be proscribed in commerce, by the strict lawr which prohibits the sale of poison to un- known persons. Arsenic is every day the instrument by which victims are sacrificed, either by the hand of wick- edness or imprudence. It is often mistaken for sugar; and these mistakes are attended with the most dreadful consequences. Whenever there is the least reason to sus- pect its presence, the doubt may be cleared up by throw- ing a small quantity of the powder upon heated coals. The smell of garlic, and the white fumes, are indications of the presence of arsenic. The symptoms which cha- racterize this poison are, a great constriction of the throat, the teeth set on edge, and the mouth strongly heated; an involuntary spitting, with extreme pains in the sto- mach ; vomiting of glairous and bloody matter, with cold sweats and convulsions. Mucilaginous drinks have been long ago given to per- sons poisoned by arsenic. Milk, fat oils, butter, &c. have been successively employed.—Mr. Navier has proposed a more direct counterpoison. He prescribes one dram (gross) of sulphure of potash, or liver of sulphur, to be dis- solved in a pint of water, which the patient is directed to drink at several draughts : the sulphur unites to the arse- nic and destroys its causticity and effect. When these first symptoms are dissipated, he advises the use of mi- neral sulphureous waters. He likewise approves of milk, but condemns the use of oils. Vinegar, which dissolves arsenic, has been likewise recommended by Mr. Sage. >-2 ORE OF COBALT. CHAPTER II. Concerning Cobalt.* COBALT was employed by artists to give a blue co» lour to glass, long before it was supposed to con- tain a semi-metal. We are indebted to Brandt, a cele- brated Swedish mineralogist, for the knowiedge of its properties, and metallic character. The specific gravity of fused cobalt is 78.119. See Brisson. Cobalt is combined in the bowels of the earth with sul- phur, arsenic, and other metallic substances. 1. The arsenical cobalt ore is of a grey colour more or less deep, dull in its fracture, and becoming black on ex- posure to the air; in consequence of an alteration in its arsenical part. This ore of cobalt crystallizes in smooth cubes, and affects several varieties. I have a piece which has the form of tetrahedral pyramids, joined base to base. This species of cobalt sometimes affects a confused crystalliza- tion in dendrites, and is then called Knit-cobalt ore^ Sometimes it is found in protuberances, stalactites, &c. The sulphureous ore of Cobalt resembles the grey sil- ver ore in its texture : it contains iron and silver; and ef- floresces of a lilac colour, mixed with a yellowish green. —Sage, Annul. Chcm. t. ii. Mr. De Lisle possesses specimens of this kind, which came from the mine of B^tnaes at Riddarhyttan. * The word cobalt is derived from cobalus, which was the name of a spirit, that according to the notions of miners haunted mines, de- stroyed the labours of the miners, and often gave tiiem a great de- gree of unnecessary trouble. The miners perhaps gave this name to the mineral out of joke, because it thwarted them as much as the supposed spun, by exciting false hopes, and rendering their labour often fruitless, for it was known at first, to what the mineral could be-applied, as it was thrown aside as useless. It was once custom- ary in Germany, to introduce into the church service, a prayer tint Cod would preserve miners and their works from kobalis and spirit* (Beckman's History of inventions.;—Am. Ed. ASSAY OF COBALT ORES. 23 3. Cobalt is mineralized by sulphur and arsenic, in the mine of Tunaberg in Sudermania.* The crystallization of this species is a cube striated on its six faces, and commonly truncated more or less deeply on its edges. This ore contains, according to Mr. Sage, fifty-five pounds of arsenic, eight of sulphur, twro of iron, and thirty-five of cobalt. 4. The ores of cobalt are sometimes in efflorescence; and the sulphureous ore forms by its decomposition the sulphate of cobalt. The sulphure of cobalt, and the arsenical cobalt ore, pass to the state of oxide in their decomposition ; and the surface becomes covered with a colour of peach flowers, more or less intense. It is sometimes coloured with an efflorescence in the figure of stars formed by radii applied to each other collaterally, and all tending to a common cen- tre. This is an indistinct crystallization, in wrhich Mr. De Lisle thinks he observed tetrahedral prisms terminated by dihedral summits. The flowers Of cobalt are frequently a mere powder, more or less coloured. Those ores which are in a state of complete decomposition are called Soft or Earthy cobalt ores. To assay an ore of cobalt, the first process is torrefac- tion. Two hundred grains are afterwards fused with an ounce and a half of black flux. Mr. Sage is confident that more metal is obtained 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 must be distilled with equal parts of the muriate of am- moniac, until the salt which sublimes in the neck of the retort has acquired a green tinge. Mr. Sage, who gives us this process, observes that seven or eight sublimations are sometimes necessary to deprive the cobalt of all the iron and bismuth which it contains. * Mr. Benjamin Henfrey informs us, that cobalt of a good quality has been found in this country, but he does not say in what part.* —Am. Ed. * Pfan for working mines, p. 3« 24 ZAFFER. AZURE. SMALT. Cobalt is of a light grey colour, compact and brittle. It is not easily fused, is not volatile, resists cupellation, and refuses to amalgamate with mercury. The working of cobalt ores is very simple. It consists in roasting the ore in a reverberator}' furnace terminating in a long chimney, into which the vapours are received. These vapours, or arsenical fumes, attach themselves to the sides, and form a crust, which is cleared off by cri- minals, who are condemned to this work for crimes that by the law deserve death. The cobalt ores of Saxony af- ford all the arsenic of commerce. When the oxide of cobalt is cleared of arsenic, it is known by the name of Zaffer. The zaffer of commerce is mixed with three- fourths of sand. This oxide, fused with three parts of sand, and one of potash, forms a blue glass, which, when pounded, sifted, and afterwards ground in mills, included in large casks, forms Smalt. In order to obtain the blue of -various degrees of fineness, the smalt is agitated in casks filled with water, and pierced with three openings at different heights. The water of the upper cock carries out the lightest blue, which is called Azure of the First Fire : the heavier particles fall more speedily; and the azure brought out by the water of the three cocks, forms the different degrees of fineness known under the names of Azure of the First, Second, and Third Fire. Bohemia and Saxony have hitherto possessed the exclu- sive power of supplying us with these products. A des- cription of these capital w orks may be seen in the minera- logical productions of Messrs. Jars. The works of Saxo- ny have been supplied, for several years, by the cobalt ore discovered in the Pyrenean Mountains in the valley of Gisten. But the Comte de Beust has formed establish- ments which secure to us the benefit of this commerce ; and he lias even been so fortunate as to find, near the vil- lage of Juget, a quartz sufficiently charged with cobalt to admit of being fused without any addition of colouring matter. The establishment of the Comte de Beust is capable of manufacturing six thousand quintals of azure, or enamel blue; and is able not only to supply our wants, but to en- Jf ABITUDE OF COBALT WITH ACIDS. 25 ter into competition with the works of Saxony for the fo- reign trade.* He has likewise, in concert with the Baron Dietrich, discovered the process of making powder blue; a secret which was exclusively in the possession of the Hollanders till the present time. Smalts are used in the preparation of cloths, laces, li- nens, muslins, thread, &c. The azures are mixed with starch, and form the blue so well known and universally used by laundresses. It is likewise employed in forming blue paintings on jfayence, porcelain, and other potteries; crystals and glasses are coloured blue by this substance; and it is also used in painting in fresco. The coarsest blues are used by the confectioners and others, in the way of ornament; and in Germany diey are used as sand for writing-paper. The consumption of smalt, azure, blue sands, and zaf- fers, in the kingdom of France only, is estimated at four thousand quintals, which are sold from seventy-two to six hundred livres the quintal. Cobalt is soluble in the acids. One part of this metal, distilled with four parts of sul- phuric acid, affords the sulphureous acid; and the residue in the retort is the sulphate of cobalt, soluble in water, and capable of crystallizing in tetrahedral rhomboidal crys- tals, terminating in a dihedral summit. Barytes, magnesia, lime, and alkalis decompose this salt, and precipitate the cobalt in the form of oxide. One hundred grains of cobalt dissolved in the sulphuric acid, and precipitated by soda, afford one hunched and forty grains of precipitate, and one hundred and sixty when precipitated by chalk. The nitric acid dissolves cobalt with effervescence. The solution affords crystals in needles, which have not been strictly examined. Tliis salt is deliquescent, boils on the coals, without detonating, and leaves a deep red calx. I * A description of the works of the Comte de Beust may be seen in the Description des Giles des Minerais, des Forges, et des Salins dee Pyrenees, par M. le Baron de Dietrich. Vol. II. D 26 HABITUDE OF COBALT WITH ACIDS. have seen this salt in very short beautiful hexahedral py- ramids. It decrepitates and fuses on charcoal. The muriatic acid does not dissolve cobalt in the cold, but by the assistance of heat it dissolves a portion of it. This acid acts more effectually upon the zaffer, and the solution is of a very fine green, and when diluted with wa- ter constitutes a very singular sympathetic ink: for it passes'from a lilac, or violet colour, to purple, green, and black..* The nitro-muriatic acid likewise dissolves cobalt, and forms the sympathetic ink, which Hellot has called the Ink of Bismitth-t Ammoniac likewise dissolves zaffer, and produces a li- quor of a beautiful red colour.^ * Green- sympathetic ink of cobalt, is prepared in the following manner : Put into an oil flask one part of cobalt and four of the nitric acid. Apply a gentle heat until the solution be nearly completed ; then add common salt equal to the cobalt employed, and four times as much water as nitric acid. If letters be written on white paper with this solution, they will be invisible; but by exposing the paper to a gently heat, they will ap- pear of a beautiful green colour.--->lm, Ed. t The acetic acid will not act upon cobalt in its metallic state, but its oxide is dissolved by it with the assistance of heat. The acetate of cobalt forms a blue sympathetic ink, which may be prepared in the following manner : Put one ounce of cobalt in fine powder into an oil flask, and add to it two ounces of nitric acid. Expose the mixture to a gentle heat, and when the cobalt is dissolved, add a solution of potash to it, until no precipitate takes place. Wash this precipitate in water, and dis- solvent in distilled vinegar, with the assistance of heat, so as to have a saturated solution. Add some sea salt, and the ink will be made.— Am. Ed. % The oxide of cobalt has been administered in rheumatism, in sy- philis, in eruptions of the skin, and in pulmonary consumption. The dose for an adult is from six to twenty grains. It excites sickness of the stomach, and proves laxative.—Am. Ed. ■NICK EI,. 27 CHAPTER III. Concerning Nickel. HYERNE appears to have been the first who treated of nickel, under the name of Kupfernickel, in 1794, in. a work on minerals. Henckel considered it as a species of cobalt, or arsenic mixed with copper. Cramer has likewise placed it among the ores of cop- per; and it was not until the year 1751, that Cronstedt ob- tained a new semi-metal from this pretended mixture. Kupfernickel is found not only in the German districts, but likewise in Dauphiny, and in the Pyrenean Mountains. In digging out a calcareous stone for building, at Bareges, and opposite St. Sauveur, small veins and lumps of nickel were found in the calcareous spar, some parts of which were reduced to the state of green oxide. Mr. Sage, who analyzed that of Biber in Hesse, and that of Allemont, found it to contain gold. In order to obtain nickel from its ore, it must first be torrefied to disengage the arsenic; and die oxide must then be fused with three parts of black flux, and a small quantity of coal. This metal is of a reddish grey colour. The specific gravity of fused nickel is 7,8070. Brisson. As it is very difficult to drive off all the arsenic by a previous torrefaction, the metal, when urged by a violent fire, still suffers arsenic to escape. The methods pointed out by Bergmann and Arvidson to purify nickel, consist in repeated calcinations and reduc- tions; but these operations separate the arsenic only; and Bergmann admits that he did not succeed in completely depriving it of its iron, though he treated it by every- suit- able method. He seems disposed to consider it as a mo- dification of iron. The Dissertation of Bergmann De Nicolo, Opuscula, t. ii. may be consulted on the nature of this metal; and also the Analyse Chimique of Mr. Sage, &c. 28 PROPERTIES OF BISMUTH. The sulphuric acid distilled upon nickel affords sulphu- reous acid, and leaves a greyish residue, which, when dis- solved in water, communicates to it a green colour. The sulphate of nickel effloresces in the air. Nickel is attacked very strongly by the nitric acid. The solution, when evaporated, affords crystals of a beautiful green, in rhomboidal cubes. The nitric acid likewise dissolves the oxide of nickel, and forms with it deliquescent crystals of a fine emerald green, and of a rhomboidal form, according to Bergmann. The muriatic acid dissolves nickel, when heated. The solution produces crystals of the most beautiful emerald green, and of the figure of long rhomboidal octahedrons. Cronstedt has taught us that nickel combines with sul- phur by fusion, and that the result is a hard yellow mine- ral, with small brilliant facets. The same chemist dis- solved this last metal in the sulphure of potash, and formed a compound resembling the yellow copper ores. Nickel does not amalgamate with mercury.* CHAPTER IV. Concerning Bismuth. BISMUTH, or tin-glass, is a semi-metal of a shining yellowish white, disposed in plates and chatoyant. It has some analogy with lead; and, like that metal, it passes off on the cupel, carrying the baser metals alona; with it. * Some chemists have asserted that nickel is magnetic ; but Mr Chenevix has shewn, that the magnetism of common nickel is owing to iron which adheres to it. A portion of this metal, so small as not to be detected by the best chemical tests, when it is combined with nickel, is susceptible of communicating magnetic properties to the whole mass, as strong as if the whole were composed of steel__ Am. E:l. ORES OF BISMUTH. 29 The specific gravity of fused bismuth is 9,8227;—See Brisson. Bismuth is the most easily fused of all the semi-metals, after tin. It requires only the 200th degree of heat. It is found in various states in the bowels of the earth, either native, or combined with sulphur, arsenic, or oxi- gene. 1. Native bismuth is sometimes crystallized in cubes :' Wallerius and Cronstedt found it in this form in the mines of Sehneeburg in S.\xony. These crystals often re-unite in the firm of dendrites, in the spathose or quart- zose gangues. Native bismuth is found in masses, cover- ed with protuberances resembling stalactites. Native bismuth is frequently altered by a slight decom- position of its metallic surface. The native bismuth of Saxony is sometimes irised, and mixed with arsenic: it has a reddish jasper for its gangue. 2. Arsenical bismuth is of a whitish and brilliant grey colour. This ore is sometimes covered with an ochre of bismuth, and often contains cobalt. I have seen pieces of arsenical bismuth, from Sehneeburg, in the form of dendrites on a gangue of jasper. 3. We are indebted to Mr. Cronstedt for the know- ledge of a sulphureous ore of bismuth. That which he has described is of a blueish brilliant grey colour. This species frequently possesses the lamellated texture of the large plated galena, which has caused Linneeus, Wallerius, and others, to give it the name of Galena of Bismuth. It is found at Batneas, at Riddarrhitan in West- manland. It decrepitates on heated coals, and requires to be pulverized, in order to torrefy it without loss. The galena of bismuth is sometimes striated. The sulphureous ore of bismuth is sometimes compact, of an obscure colour, sprinkled with small brilliant points. That of Sehneeburg in Saxony is of this kind. Mr. De La Peyrouse discovered, in 1773, on the moun- tains of Melles in Cominges, 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 of thirty-five livres per quintal. oO HABITUDES OF BISMUTH. 4. Cronstedt, Linnanis, Justi, and De Born, have spo- ken of a bismuth ore of a greenish yellow, found in Saxo- nv, and in Sweden. Mr. Sage communicated to the Aca- dcmv, on the 17th of August, 1780, the analysis of an earthy, solid, jellowish green ore of bismuth. He obtain- ed quartz in the proportion of one-third, some carbonic acid, thirty-six pounds of bismuth per quintal, and twenty- four grains of silver: he found neither copper nor iron. Besides this green ore, he analyzed a yellow, solid, slightly brilliant, and sometimes semi-transparent ore, which af- forded him nearly die same results, but nine pounds more of bismuth. This oxide must be fused in the blast furnace. The fusibility of bismuth renders the working of this ore very simple, and the apparatus may be varied in se- veral way s. Nothinginore is necessary than to throw the ore into the fire, and to make a cavity underneath to re- ceive the semi-metal. Bismuth, when heated to redness, burns with a blue flame, seaicely perceptible. Its oxide rises in the form of a yellowish fume, which, when condensed, forms the flowers of bismuth. Its weight is increased twelve per cent, in passing to the state of oxide. Mr. Darcet has converted bismuth into a glass of a dull violet colour. Bismuth may be substituted instead of lead, in the pro- cess of cupellation. Its vitrification is even more speedv. The sulphuric acid, boiled on bismuth, suffers sulphu- reous acid to escape, and partly dissolves the semi-metal. The sulphate of bismuth does not crystallize, but is very deliquescent. The nitric acid attacks bismuth, and is very speedily decomposed. Nitrous gas is disengaged, Avhile the oxi- gene is fixed in combination with the metal. There is ne- vertheless a portion dissolved which is capable of forming a salt in rhomboidal, tetrahedral prisms, terminating in a tetrahedral pyramid with unequal faces. This nitre deto- nates weakly with reddish scintillations ; and melts, swells up, and leaves an oxide of a greenish yellow colour. This salt loses its transparency in the air, at the same time that its water of crystallization flies off. 5IACISTERY OF BISJJUTH. 31 The muriatic acid does not act on bismuth but in* the course of a considerable time; and for this purpose it must be highly concentrated. The muriate of bismuth is of difficult crystallization, and strongly attracts the hu- midity of the air.* Water precipitates this semi-metal from all its solu- tions ; and the precipitate, when well washed, is known by the name of magistery of Bismuth, or white paint for the complexion. This white is used as a pigment for the skin; but strong or sulphureous vapours, and even the animal transpiration, convert it into metal, and alter its colours. The hair-dressers, when they are desirous of converting hair to a black colour, smear it with pomatum prepared with the magistery of bismuth. Bismuth is used by the pewterers to give hardness to the metallic composition of pewter. Mr. Pott has published a dissertation, in which he af- firms that physicians have made use of some preparations of this semi-metal; but it is proper that it should be pro- hibited, because it almost always retains a portion of ar- senic, and itself partakes of the noxious properties of lead. The white of bismuth is very much used as a paint for the complexion. Its various solutions form sympathetic inks, which are more or less curious, on account of the facility with which this oxide is altered, and becomes black. Schluter, in his Treatise of the Fusion of Ores, pre- tends that it may be used in making the azure blue glass. But it appears, from his own account, that he made use of a bismuth ore very rich in cobalt. For he says, that a moderate fire causes this ore to suffer its bismuth to flow out, and that residue is a grey and fixed earth, which may be employed to advantage in making the blue. This semi-metal unites with all the metals; but very difficultly, in the way of fusion, with the other semi-me- tals, or the metallic oxides. Antiniony, zinc, cobalt, and arsenic refuse this union. Bismuth, fused with gold, renders it eager, and com- municates to it its own colour. It does not render silver * Bismuth inflames in ©xigenated muriatic acid gas.—4m. Ed, 32 ALLOYS OF BISMUTH. so brittle as gold : it diminishes the red colour of copper, but is deprived of its own colour by uniting with lead; the two metals, in this case, forming an alloy of a dark grey colour. When bismuth is mixed in a small propor- tion with tin, it gives it a greater degree of brilliancy and hardness. It may be united with iron by a violent heat. Bismuth amalgamates with mercury, and forms a fluid alloy ; a circumstance which has induced certain unprin- cipled druggists to mix it with that metal. The fraud may be known from the mercury- being less fluid than be- fore, and no other test is necessary than to dissolve the mixture in spirit of nitre ; for the bismuth will be preci- pitated by the addition of water. This property, however, of amalgamating completely with mercury, may cause it to be applied with advantage in the silvering of glasses, by an amalgam of tin, bis- muth, and mercury. This is, perhaps, the circumstance which has obtained it the name of tin-glass. The fusible alloy of Mr. Darcet is a mixture of eight parts of bismuth, five of lead, and three of tin. It melts in water at the seventy-third degree of Reaumur, and flows like mercury.* CHAPTER V. Concerning Antimony. ANTIMONY is a semi-metal which has singularly engaged the attention of alchemists. They consi- dered it as the basis of their great wrork; and it is de- * Baume has given the magistery of Bismuth in three cases of chronic diseases of the stomach with success. The dose at first was one grain three times a day, and it was increased one grain every other day lo six grains for a dose. According to Schroeder, the acetate and tartrate of Bismuth are purgative. Of the latter he says—" Serum purgat potentissime, hydropecos ad miraculum juvat." The calx of this metal is in- serted in the Stras.burg Pharmacopoeia, and it is said to be an ex- cellent remedy in the intermittent fever.__Am. Ed. ARSENICAL ORE OF ANTIMONY, 33 scribed in their writings under the names of the Radical Principle of Metals, Sacred Lead, &c. This semi-metal is famous for the disputes which were maintained 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. Poumier of Caen, a skilful physician and chemist, was degraded by the Fa- culty of Medicine, for having employed it in 1609. This same proscribed metal was re-established in 1624; and at present affords the most powerful remedies pos- sessed by the medical art. Bazilius Valentinus, a zealous partisan of antimony,- pleaded its cause with much warmth and enthusiasm, in a work entitled Currus Triumphalis Antimonii t and Le- mery has written a large volume to decry the preparations of this semi-metal. As this subsfance afforded employment for a long time to the alchymists, its study is rendered particularly diffi- cult by the multiplicity of preparations, and the barbarous names which have been given to them, and to the variety of processes. But by confounding preparations of the same nature; by bringing the analogous products toge- ther, rejecting at the same time the numerous list of bar- barous names which have been bestowed on one and the same thing; and by reducing the processes to that sim- plicity of which the well-known preparations are suscept- ible ; we may succeed in forming an accurate and precise idea of the nature and properties of this metal. Antimony is found in the bowels of the earth, in four different states. 1. In the metallic form. 2. Combined with arsenic. 3. Mineralized with sulphur. 4. In the state of oxide. 1. Some authors pretend that antimony in the metallic state was discovered in the year 1748, by Ant. Swab, in the mine of Sahlburg, in Sweden. Swab affirms that it has the colour of silver, that its texture is formed of large brilliant plates, and that it easily amalgamates with mer- cury. Cronstedt, Wallerius, Linnaeus, and Cartheuser, do not hesitate to admit of native antimony; but Leh- man, Justi, and Vogel deny its existence : and Mr. De Vol. II. E 34 , ARSENICAL ORE OF ANTIM0X7. Lisle thinks that this pretended regulus is nothing but the white arsenical ore of antimony. The abbe Mongez af- firms that he has discovered native antimony at Allemont in Dauphiny. It is the same ore which Mr. Sage has de- scribed under the name of the Arsenical Ore of Anti- mony. If this native Antimony really exists, it is probably crystallized like the metal itself, which is known to us, and whose crystals are either octahedrons inserted one in the other, or cubes placed one upon each other slant- wise. 2; The arsenical ore of antimony may be considered as a true regulus by those who, after Bergmann, do not admit of arsenic as a mineralizer: for the ore is then con- sidered as an alloy of the two reguli. This ore is as white as silver, and exhibits large facets like antimony. The specimen was sent from Allemont in Dauphiny, to Mr. Sage. Its gangue is quartz. Small fasces of the grey and red ores of antimony striated and radiated, and not containing arsenic, are sometimes found in the cavities of this stone. The antimony and the arsenic exist in the metallic state in this ore. The arsenic adheres so strongly to the anti- mony that it cannot be disengaged by torrefaction. Mr. Sage combined the ore with sulphur, and obtained orpi- ment and realgar. This mineralogist has concluded, from his analyses, that the arsenic existed in the proportion of sixteen pounds in the hundred. 3. Aptimony is usually minendized by sulphur, in which combination it exhibits three or four very distinct x'arieties. It is sometimes crystallized of a grey colour inclining to, blue. The crystals are very frequently slen- der, oblong, hexahedral prisms, terminated by tetrahe- dral pyramids. The mines which are wrought in Au- vergne afford us beautiful prisms, of the same geometri- cal form, but thicker than those of the antimony of Hun- gary. These last crystals soon become of an irised co- lour ; but those of the mines of Auvergne are not so speedily changed. I possess a large specimen of anti- mony from the neighbourhood of Alais, which is entirely covered with crystals perfectly similar to those of Hun- gary. It frequently happens Uiat these crystals are con- SULPHUREOUS ORE OF ANTIMONY. 35 fused and indistinct, in which case the ore appears to be formed of very slender prisms applied sidewise to each other. That which is called plumose antimony does not differ from these varieties, excepting that its crystals are very slender and detached. They are usually of a black- ish grey. This variety has been arranged among the ores of silver, because for the most part it contains that metaL Ores of antimony have been found in several parts of France; but our province of Languedoc exhibits very curious specimens. We have them at Malbos in the county of Alais. This mineral has been wrought in the diocese of Uzes; but the want of consumption has pre- vented the we-rks from going on with spirit. Mr. De Gensanne has observed in Vivarais a large vein of ore of antimony in a stratum of pit-coal.'* The decomposition of the sulphureous ore of antimony produces the red antimonial ore. The red ore more es- pecially accompanies the specular antimony of Tuscany. Its surfaces appear to be corroded or rendered carious by decomposition; and when a piece is broken, it emits a powder which has the properties of kermes. The decomposition of sulphureous antimony likewise produces the sulphate of antimony. Some varieties of these antimonial decompositions may likewise be seen in the Analyse Chimique of Mr. Sage. Antimony is found in two states in the course of trade; namely, in the form of crude antimony, and in the me- tallic form. Crude antimony is nothing else but the sulrjhureous ore of antimony cleared of its gangue. For this purpose the ore is put into pots pierced at the bottom, and disposed upon other pots buried in the earth. The uppermost pots which contain the mineral are then heated; the antimony becomes fused, and flows, together witii its sulphur, into * It is said that antimony has been found in New-Jersey, and that a specimen was taken from a vein of that metal, at Sagherties, be- tween Esopus and Kaatskill, in the state of New-York. It is re- ported to exist there in considerable quantity.*—Am. Ed. * Medical Repository, Hexade 2, vol. iv. p. 304. Drayton informs us, that it is also met with in the upper parts t$ South-Carolina. 36 PROCESSES, &C. WITH ANTIMONV. the lower vessels, while the gangue remains in the upper pots. . As the mixture of antimony, and sulphur is very fusi- ble, this process may be varied in a thousand ways. I have myself wrought an antimonial ore with the greatest ceeonomy, by fusing it in a furnace, over the arch of which I had disposed the ore broken into pieces of five or six pounds w eight each. The heat was communicated to the whole mass by five openings in the arch or roof; and the antimony, as it melted, ran down on the outside of the , furnace by means of channels cut in the convex part of the dome. This method afforded forty quintals of anti- mony in twenty-seven hours, by the consumption of be- tween twenty and thirty quintals of combustible matter. We are acquainted w'ith two methods of depriving crude ' antimony of its sulphur. 1. The slow and gradual cal- cination of the ore, which affords a grey oxide, and this urged by a violent heat is converted into a reddish and partly transparent glass of antimony. It does not assume this transparence unless it has been perfectly fused. The glass of antimony is a violent corrosive, but is capable of being conected by mixing or kneading it with yellow wax, and afterwards burning of the wax; or otherwise by triturating it with a volatile oil. This is the cerated antimony of Pringle, so much extolled in dysenteries. 2. Or otherwise, the antimony may be deprived of its sulphur by projecting into an ignited crucible a mixture of eight parts of crude antimony, six of tartar, and three of nitre. By keeping this mixture for a certain time in fusion, the antimony is obtained in the metallic state. In the large works antimony is torrefied in an oven re- sembling that of the bakers. Fifty pounds of dried wine lees or tartar are mixed with a hundred pounds of the ox- ide of antimony, and the mixture is then fused in proper crucibles. The metallic button contains the form of the crucible; and these loaves of antimony exhibit a star on their upper surface, which has been considered as pecu- liarly characteristic; but is in fact nothing more than a confused crystallization formed by octahedrons inserted one in the other. HABITUDES OF ANTIMONY. 37 Copper, silver, and iron, when fused with the sulphure of antimony, seize its sulphur, and reduce it to the state of regulus. This has been distinguished by the name of the metal employed. Thus we hear of the regulus of Mars, of Venus, &x. Antimony is difficult of fusion; but when once melted, it emits a white fume known by the name of Argentine Snow, or Flowers of Antimony. These fumes, when collected, form very brilliant prismatic tetrahedral cry- stals : Mr. Pelletier has obtained them in transparent oc- tahedrons. The argentine flowers of antimony are solu- ble in water, which they render emetic. The volatility and solubility of this sublimed oxide exhibit a resem- blance with the oxide of arsenic before treated of. We are indebted to Rouelle for these observations on the properties of this antimonial oxide. Antimony is very slightly changed by exposure to air, in which it long preserves its brilliancy. The specific gravity of fused antimony is 6,7021.— See Brisson. The sulphuric acid, by slow ebullition upon this metal, is partly decomposed. Sulphureous gas first escapes, and sulphur itself is sublimed towards the end. When four parts of the acid are used with one of the antimony, the residue, after the action of the acid, consists of the. me- tallic oxide, with a small quantity of the sulphate of anti- mony, which may be separated by means of distilled wa- ter. This sulphate is very deliquescent, and is easily de- composed in the fire. The nitric acid is decomposed upon this semi-metal with great facility. It oxides a considerable -part, and dis- solves a portion, which may be suspended in water, and forms a very deliquescent salt, decomposable by heat. The oxide prepared by this means is very white, and verv difficult of reduction. It is a true bezoar mineral. The muriatic acid acts upon antimony only by a long- digestion. Mr. Fourcroy has observed that this acid, long digested upon the metal, dissolves it; and that the muriate of antimony, obtained by a strong evaporation in the form of small needles, is very deliquescent. It is fu- sible in the fire, and likewise volatile. Mr. Monnet has proved that twelve grains of the oxide of antimony are 38 ANTIMONIAL PREPARATIONS. sufficient to saturate half an ounce of the ordinary muri- atic acid. Messrs. Monnet and De Fourcroy have al- ways found that there is a portion of the muriate of anti- mony which is not volatilized by the fire: this depends upon its being strongly oxided or calcined. If two parts of the corrosive muriate of mercury, and one of antimony, be distilled together, a very slight de- gree of heat drives over a butyraceous matter, which is ealled butter of antimony, or the sublimed muriate of an- timony. It may be presumed that the acid in this com- position is in the state of oxigenatcd muriatic acid, as it is in the corrosive sublimate. The sublimed muriate of antimony becomes fluid by a very gentle heat; and by virtue of diis property it may conveniently be poured from one vessel to another : for nothing more is necessary than to plunge the bottle which contains it into hot water, and the muriate may then be poured out in its liquid state. I have several times observed this muriate of antimony erystallized in hexahedral prisms with dihedral summits : two sides of the prism are inclined, and form that which •he ancient chemists distinguished by the name of cry- stals in the form of a tomb. This muriate is used as an escharotic. When the salt is diluted with water, a white powder falls down, called powder of algaroth, or mercu- ■rius vitas. This powder does not contain an atom of the muriatic acid, and is merely an oxide of antimony pro- educed by that acid. Simple water has some action upon this semi-metal.; for we find that it becomes purgative by remaining in contact with it. Wine, and the acetous acid, completely dissolve it: but the emetic wine is an uncertain remedy; because it is impossible to determine with absolute cer- tainty the degree of its energy, which depends upon the very variable degree of acidity of the wine made use of. The emetic wine ought not therefore to be used but in ex+ernai applications. The gastric fluids likewise dissolve this semi-metal, as is proved by the famous perpetual pills. This purgative has been distinguished by the name of Perpetual Pills; because, being very little alterable, the pill may be trans^ mittedirom generation to generation. ANTrMONTAL PREPARATIONS. 39 The acid of tartar forms a very well known salt with antimony, which is much employed in medicine under the name of Emetic Tartar, Stibiated Tartar, or simply E- metic. It is this salt which, in the New Nomenclature, is distinguislied by the name of Antimoniated Tartrite of Potash. In the examination of the various authors who have treated of the preparations of this remedy, as well as by comparing the most celebrated dispensatories, we do not find two which propose an uniform process which is con- stant and invariable in its effects. Some prescribe the crocus metallorum, or semi-vitre- ous oxide of sulphurated antimony ; others the glass of an- timony ; others the liver of antimony, or sulphurated ox- ide of antimony; and others the sublimed oxide : some combine several of these substances. But all in general adopt cream of tartar, or the acidulous tartrite of potash, as a solvent. The processes vary not only in the choice of the sub- stances to be made use of, but even in the proportions in which they are to be employed. We likewise find vari- eties in the quantity of water used as a vehicle, which is not an indifferent circumstance; in the time prescribed to digest the substances together, a circumstance of the greatest consequence to be ascertained, because the satu- ration of the acid depends absolutel) and essentially upon it. The choice of vessels must likewise influence the ef- fect of this remedy. Hoffmann has affirmed that the emetic lost its effect by a long ebullition; and Mr. Bau- me has proved that iron precipitates the antimony after a time, and consequently that the iron vessels prescribed in certain dispensatories ought to be rejected. This variety in the processes must necessarily influence the result; and we cannot be much surprised that Geof- froy, who analyzed several antimoniated tartrites of pot- ash, should have found from thirty grains to two gross and ten grains of metal in the ounce of this salt. Is it not therefore of great consequence to prescribe a uniform process, whose product should be invariable. These heroic remedies, which operate in small doses, ought to produce constant and invariable effects through all Europe. It would be much more advantageous that 40 ANTIMONIAL PREPARATIONS. solemn proceedings should be made for the preparation of these active remedies, than for the composition of the the- riaca, a true pharmaceutic monster, the dose of which may with impunity be varied from a few grains up to three hundred. It follows, from the variety of the effects of these sovereign remedies, that consultations become almost- ineffectual ; because the physician prescribes according to the effects of the remedies he is in the habit of using : and the art of medicine becomes no better than a discou- raging alternative of success and disappointment. At Montpellier, the emetic acts in a dose of one or two grains; but in other places it does not operate in a less dose than ten or twelve : and the stibiated tartar sold by those wholesale dealers in medicine, who supply the country apothecaries, is usually nothing but the sulphate of potash, or vitriolated tartar moistened with a solution of emetic tartar. It is a thing greatly to be desired, that go- vernment, which does not apply its stamp of approba- tion to objects of luxury until they have passed a rigid inspection, should prohibit traders from circulating with impunity, products upon which the health of the citizen so essentially depends. These are the frauds and decep- tions which have engaged me to form an establishment of chemical products, in which intelligence and probity pre. side over all its operations; and I have succeeded in my laboratories so far as to conduct the processes writh suffi- cient economy to afford products faithfully made up, and invariable in their effects, at the same price as those so- phisticated drugs with which the public has hitherto been poisoned. The most accurate process for making an excellent emetic consists in taking very transparent glass of anti- mony, grinding it fine, and boiling it in water, with an equal weight of cream of tartar, until this salt is satu- rated. By filtration, and evaporation with a gentle heat, and subsequent repose, crystals of the antimoniated tar- trite of potash are obtained, whose degree of emeticity appears to be sufficiently constant. The crystals may be obtained in several successive products by repeated eva- porations. Macquer proposed the powder of algaroth, as more v.niform in its power. Messrs. De Lassone and Durande ANTIMONIAL PREPARATIONS. 41 have adopted the opinion of Macquer; and the celebrated Bergmann has followed the ideas of the French chemists, with a few slight modifications. Take five ounces of cream of tartar reduced into pow- der, and two ounces two gros of the powder of algaroth precipitated by hot water, washed and dried. Add wa- ter to these, and boil them gently. By filtration and eva- poration the crystals of emetic tartar are obtained; which may be given in "the dose of three grains, without fa- tiguing the stomach or intestines. The antimoniated tartrite of potash crystallizes in tri- hedral pyramids. It is very transparent, is decomposed on the fire wTith crackling, and leaves a coaly residue. Sixty parts of water dissolve it. It effloresces in the air, and becomes farinaceous. The solutions of this salt throw down a mucilage, which fixes, and forms a pellicle of considerable thickness : it is the mucilage of cream of tartar, which is insoluble in water, and partly soluble in alcohol. The sulphuric acid blackens it, but does not it- self become coloured till after a long -time. The nitric acid dissolves it partly; and is itself decomposed, with the emission of much nitrous gas. The alkalis and lime decompose the antimoniated tar- trite of potash. Antimony, properly mixed with the ni- trate, decomposes that salt completely. Equal parts of the semi-metal and nitre being thrown into an ignited cru- cible, the salt detonates, its acid is decomposed; and at the end of the operation the crucible is found to contain the alkali which served as the base of the nitrate, and the antimony reduced to the state of white oxide: this is called Diaphoretic Antimony. The same preparation may be made by using *the sulphure of antimony; in which case three parts of the nitrate are used to one of the crude antimony. The residue in the crucible, after the detonation, is composed of the oxide of antimony^ fixed alkali, a portion of the nitrate not decomposed, and a small quantity of sulphate of potash. This compound is still known by the name of the Solvent of Rotrou. Water deprives it of all the salts it contains; and leaves only the oxide of antimony, which is called Washed Di- aphoretic Antimony. If a small quantity of acid be poured on the fluid which holds the salts in solution, a Vol. II. F 12 ANTIMONIAL PREPARATIONS. small portion of the oxide of antimonv falls down, which was dissolved by the alkali of the nitre. The precipitate forms the ceruse of antimony, or the pearly matter of Kerkringius. Equal parts of the sulphure of antimony and of nitrate- of potash, detonated in an ignited crucible, form the liver of antimony or sulphurated oxide of antimony; which, when pulverized and washed, produces the saffron of me- tals, or crocus metallorum. The oxides of antimony have been considered as very difficult of reduction ; and it was not without surprise that i at first observed the facility with which they are all re- ducible by the black flux. This prejudice was established and propagated for want of proper experiments. The alkalis do not sensibly act upon antimony: but the sulphures of alkali dissolve it completely; and it is upon this principle that an operation is founded by which we ob- tain a valuable remedy, known by the name of Kermes Mineral, to distinguish it from the vegetable kermes used in.dying. The preparation is simply a red sulphurated oxide of antimony. This remedy, first pointed out by Glauber, who made it with antimony and the solution 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 Pow- der of the Chartreux. This religious man obtained the composition from a surgeon named Laligerie, to whom it had been given by Mr. Chastenay, lieutenant at Landau. Mr. Dodart, first physician to the king, bought the secret in the year 1720; and Mr. Laligerie rendered it public. According to his process, the pounded sulphure of anti- mony is boiled for twro hours, with one fourth of its weight of the solution of fixed nitre or potash, in twice its weight of very pure \vater. After ebullition the fluid is filtered; the kermes falls down as it cools, and is afterwards dried. Laligerie directs that more of the solution of fixed nitre be digested on the metal, till it is completely dissolved. La- ligerie burned spirit of wine or brandy upon it. The li- quor which remains after the kermes is fallen down, con- tains more kermes, which may be disengaged by means of an acid. This kermes, which is paler than the former. ANTIMONIAL PREPARATIONS. 43 is known by the name of Golden Sulphur of Antimony, or the orange-coloured sulphurated oxide of antimony. This process is no longer used. That which succeeded the best with me, consists in boiling ten or twelve pounds of pure alkaline solution with two pounds of the sulphure of antimony. The ebullition is continued for half an hour, after'which the fluid is filtered; and much kermes is ob- tained by mere cooling. I digest new alkali on the anti- mony, until it is consumed. The kermes which I obtain by this means is of a beautiful tufted appearance.* Geoftroy, who analyzed the kermes in 1734 and 1735, found that one gros of kermes contained from sixteen to seventeen grains of antimony, from thirteen to fourteen grains of alkali, and from forty to forty-one of sulphur. But Messrs. Baume, Deyeux, de la Rochefoucauld, and De Fourcroy, are convinced that the washed kermes does not contain an atom of alkali which is not necessary to its virtues. Kermes is likewise one of those remedies in the prepa- ration of which the greatest care ought to be taken. It is nevertheless a substance which all the apothecaries in the country buy at the fair of Beaueaire ; and the analysis which I have several times made of this kermes, has con- vinced me that it very often is nothing else but pounded brick, mixed with vegetable kermes, and sprinkled with a strong solution of emetic tartar. I have found some * Kermes Mineral is prepared by Goetling, in the following man- ner : Reduce separately to powder, and afterwards mix sixteen parts of crude antimony, twenty-four parts of purified potash, and three parts of flowers of sulphur ; introduce the mixture into a crucible, and let it enter into complete fusion. After it has cooled, pulverise the mass, and boil it for half an hour, in one hundred and twenty- eight parts of water; filter it while boiling through a thick cloth, let- ting it run into an earthen pan, containing one hundred and fifty-six parts of water, and leave it exposed to the air in a shallow vessel for two or three days, or until particles of a bright orange colour appear on its surface. Afterwards decant the liquid, wash the deposite in a large quantity of water, then remove it on a filter, and complete the edulcoration ; when this is done, dry it by a gentle heat. This process yields twelve or fourteen parts of the kermes, of a fine red brown colour ; the whole quantity of antimony, except a tri- fling residuum of extraneous matter, is dissolved and converted into kermes, and only a very small quantity remains in the decanted liquor,, in the form of golden sulphur of antimony.—Am, Ed, 44 ANTIMONIAL PREPARATIONS^ which was merely a mixture of the fine brown red and the calx of antimony. Lime and lime-water, digested upon pulverised anti- monv, afford, even in the cold, at the end of a certain time, a kind of kermes, or golden sulphur of a beautiful red colour.* Antimony enters into the composition of printers' types. It is likewise mixed with tin to increase its hardness. It was formerly used as a purgative: for this purpose it was made into cups, in which water or wine was suffered to stand for a night, and taken by the patient the following day. The sulphure of antimony is used as a sudorific in skin disorders. For this purpose it is tied in a cloth, and di- gested in the ptisans appropriated to these disorders. It is administered in pills for the same purpose. The solvent of Rotrou has been much used to dissipate lymphatic concretions, and pituitous swellings. Washed diaphoretic antimony is used in considerable doses to excite perspiration. Some physicians have con- sidered it as a medicine void of effect; and Boerhaave has maintained that its effect is not more considerable than that of Lemnian earth. The kermes mineral is one of the most valuable medi- cines that the healing art is acquainted with. It is inci- * There is a celebrated quack medicine of great repute in Eng- land, known by the name of James's Powders. The analysis of this powder, made by Dr. Picrson some years ago, led the College of Physicians of London to adopt an antimonial preparation, as a pro- posed substitute for the empiric medicine, which is termed the ftul- vis antimonialis. This is prepared by calcining together, first in a gentle and afterwards in an intense heat, equal weights of hartshorn shavings and crude antimony, so that the powder when prepared, is a mixture of phosphate of lime and oxide of antimony. Mr. Chenevix has proposed the following method of preparing the same powder in the moist way, which will be more uniform in its quality, and perhaps made with greater ease. Dissolve, together or separately, in the least possible portion of mu- riatic acid, equal parts of the white oxide of antimony, (procured by adding pure water to the butter of antimony) and of phosphate of lime. Pour this solution gradually in distilled water, previously alka- lized by a sufficient quantity of caustic ammoniac. A white and abundant precipitate will take place, which when well washed and dried, is the substitute proposed for James's powder.—4m. Ed. CHARACTERS OF ZINC 45 ^.ive; and may be administered in all pituitous cases, when the stomach fails, and the lungs are obstructed. In a more considerable dose it is sudorific, and a still larger portion is emetic. It is employed in the dose of from half a grain to three. The tartar emetic has received its name from its uses. It is dissolved in water; and this solution produces its effect. The liver of antimony, crude antimony, and the crocus metallorum, are more especially used as purgatives in the veterinarian practice. They are given to horses in the dose of about an ounce.. CHAPTER VI. Concerning Zinc. ZINC is a metallic substance of a blueish brilliant white colour, very difficultiy reducible into powder, but capable of being extended into very thin plates by the equal and gradual pressure of the flatting-mill. From this last property, which has been proved by Mr. Sage, we may consider zinc as the intermediate substance between semi-metals and metals. Zinc is found naturally in various states. 1. Cronstedt affirms that he saw a radiated crystalliza- tion of a metallic appearance, which is found at Sehnee- burg, where it is called flowers of bismuth, but which he found to be the regulus of zinc. This celebrated minera- logist does not venture to pronounce that it is native zinc. Mr. Bomare affirms that he found it in small pieces in the mines of lapis calaminaris in the dutchy of Limbourg, and in the zinc mines of Goslar. * This regulus may have arisen from the scoriae of furnaces, or from the ancient wrorks; so that the existence of native zinc is still consi- dered as very doubtful by these mineralogists. 2. Zinc is usually mineralized by sulphur, forming an ore known by the name of Blende, which in German sig- 46 ASSAY OP BLENDE. nifies blinding or deceitful; a name which may have been given to it because such districts as abound with this mi- neral are barren of other ores. The determinate crystallization of blende appears to be the alumini-form octahedron, and sometimes the tetrahe- dron; but the modification of these primitive forms are so numerous, that the crystals are found in an astonishing variety of figures. Most commonly they are polyhedral crystals of an indeterminate form, or scarcely capable of being described. On this circumstance depend the deno- minations of Blende with Large or Small Plates, Striated Blende, Compact Blende, and other species, which may be seen in the works of Messrs. Sage, De Lisle, &.C. The colour of these blendes is infinitely various; they are found yellow, red, black, semi-transparent, &c. All the blendes emit an hepatic smell when grated or triturated. There is a kind of blende which exhibits a line of phos- phoric flame when scratched with a knife, or even with a tooth-pick. Mr. De Bournon found this yellowish, trans- parent, and phosphoric blende, similar to that of Scharf- fenburg, at Maronne in the mountains of Oisan, at the dis- tance of nine leagues from Grenoble. The phosphoric blende contains scarcely any iron. To make the assay of a blende, Mr. Monnet advises solution of the ore in aqua fortis. The acid unites with the metal, and separates the sulphur: after which the oxide of zinc may be obtained by distilling off the acid; and this may be reduced. Bergmann obtains one part of the sul- phur of these ores by distillation, dissolves the residue in acids, and precipitates the metal from its solutions. Mr. Sage distils blende with three parts of sulphuric acid : the sulphur sublimes by this operation; and the residue in the retort is the sulphate of zinc, mixed with a small quantity of sulphate of iron, and other substances mixed with the Zinc. I do not know any country where blende is wrought to obtain the zinc : but it is sometimes mixed with lead; and in the working of this last metal the former is occasi- onally obtained. Such is the ore worked at Rammelsburg near Goslar, in the lower Hartz. Great part of the zinc is dissipated during the fusion of the lead ore; but a por- tion of this metal is obtained by a very ingenious process. ORES OF ZINC, 47 Care is taken to keep the anterior part of the furnace cool; against which a stone is placed with a slight degree of in- clination. The vapours of the zinc which are carried against this stone, are condensed, and fall in drops into powder of charcoal; with which a stone placed at the bottom is covered. The semi-metal is defended from oxidation by means of the charcoal; and it is afterwards fused, and cast into convenient forms. This zinc is always united with a small quantity of lead, and is less pure than that which comes to us from India, under the name of Tutenag. I strongly calcined the blende of St. Sauveur, and mixed the powder with charcoal. I then put the whole into a retort whose orifice was plunged beneath water; and by a violent heat, kept up for two hours, I obtained much zinc, which fell to the bottom of the water. 3. The decomposition of blende gives rise to the for- mation of the sulphate of zinc. The operation of na- ture is slow, but art has supplied its defect. All the sul- phate of zinc which is met with in commerce, is pre- pared at Rammelsburg. For this purpose, after having roasted the galena mixed with the blende, it is thrown ignited into cisterns full of water, where it is left for twenty-four hours. The roasted mineral is three times extinguished in the same water; after which the lixivium is evaporated, and put into coolers. At the end of fif- teen days the water is decanted, in order to separate the crystals of the sulphate of zinc. These crystals are af- terwards fused in iron vessels; and the liquor is poured into coolers, where it is stirred till it congeals. We shall examine the properties of this salt in due course. 4. Zinc is likewise found in the state of oxide; and it appears to me that nature makes use of two means of converting the metal to this state. 1. The sulphur is sometimes dissipated without the production of sulphate: in which case it is replaced by the oxigenous gas, and the result is that oxide of zinc which is known by the name of Lapis Calaminaris. I have found strata of lapis cala- minaris, at St. Sauveur, intermixed with layers of blende; and the transition of the blende to the state of lapis cala- minaris may be followed in the most interesting manner. 2. The -sulphate of zinc produced by the decomposition 48 ANALYSIS OF CALAMINE. of blende in certain circumstances, is itself decomposed by calcareous stones. In the rich collections of Messrs. Sage, De Lisle, &c. we see crystals of calcareous spar converted into calamine at one end, and calcareous at die other. Calamine crystallizes in rhomboidal tetrahedral prisms, or in hexahedral pyramids. It is sometimes covered with protuberances; often has the appearance of being worm-eaten; and is, at other times, either spongy or compact. Its colour varies greatly. The county of Somerset af- fords it of white, green, and other colours. To make a good analysis of calamine, Bergman ad- vises solution in the sulphuric acid; he obtains the sul- phates of iron and of zinc. That of iron is decomposed by a known weight of zinc ; and the metal is afterwards precipitated by the carbonate of soda. He has ascertained that ninety-three grains of this precipitate are equivalent to one hundred grains of zinc; and from this weight he deducts that of the zinc made use of to precipitate the iron. Zinc may be obtained from calamine by distillation. For this purpose I have used the same process as has al- ready been mentioned in treating of blende. Zinc yields beneath the hammer, without extending itself. If it be cast into small plates, it may then be laminated, and reduced into very thin and very flexible leaves.* The specific gravity of fused zinc is 7,1908. See Brisson. Zinc, when heated, may be easily pulverized. This operation is very difficult without this precaution indi- cated by Macquer ; for it wears and chokes up files, and destroys them in a short time: besides which, they have no considerable action upon it. It may likewise * Zinc is a malleable metal at a temperature between 210° and 300° of Fahrenheit's thermometer. It yields to the hammer and may be drawn into wire, if kept at this temperature during the operation. They say, that after being annealed and wrought, it continues soft, flexible and extensible, and does not return to its partial brittleness, but may be bended and applied to many uses for which it has been hitherto thought unfit.—Am, Ed. i PROPERTIES OF ZINC. 49 be fused and poured into water.—These are the most convenient means of pulverizing it. Zinc, treated in close vessels, sublimes without de- composition : 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 redness, it takes fire, emits a blue flame; and white flocks issue from it, which are called Philosophical Wool, Pompholix, or Nihil Album. This oxide may be fused into glass by an exceedingly violent heat: the glass is of a beautiful 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 Lassone, who has written several excellent Memoirs on zinc, considers it as a kind of metallic phosphorus. Water appears to have some action upon zinc. When this semi-metal begins to be ignited, il water be poured on it, the fluid is decomposed, and much hydrogenous gas is disengaged. Messrs. Lavoisier and' Meuisner have ascertained this fact, in their fine experiments on the decomposition of water. Sulphuric acid dissolves it in the cold, and produces much hydrogenous gas. A salt may be obtained by eva- poration, in tetrahedral prismatic crystals, terminated by a four-sided pyramid. Mr. Bucquet has observed that these prisms are rhomboidal. This salt is known by the name of Vitriol of Zinc, White Vitriol, Sulphate of Zinc : its taste is considerably styptic. It is not much altered by exposure to air when pure; but suffers its acid to escape, at a degree of heat less than is required by the sulphate of iron.* * The crystallized acetite of zinc is considered as one of the best applications, in all cases of gonorrhaea. For the purpose of an injection, eight or ten grains are dissolved in four or six ounces of water, or in a thin mucilage of quince seed, or a decoction of linseed or barley, increasing or diminishing it in strength, so as to excite a slight smarting. The following is the best method of preparing it. To a solution of the sulpiiate of zinc, in eight times its weight of water, add a solution of acetite of lead, in twice its weight of water, as long as any precipitation ensues, or a little longer, in order to insure the complete decomposition of the white vitriol. Throw the whole upon a linen strainer, and wash off the soluble part by repeated affusions of distilled water.—Am. Ed. Vol. II. G 50 • HABITUDES OF ZINC The nitric acid attacks zinc with vehemence, even when diluted with water. In this operation a great part of the acid is decomposed; but if the residue be concen- trated by slow evaporation, crystals are obtained in com- pressed and striated tetrahedral prisms, terminated by py- ramids with four sides. Mr. De Fourcroy, to whom we are indebted for tiiis observation, adds, that the salt melts upon heated coals, and spreads abroad with decrepitation, and a small reddish flame. If it be exposed to heat in a crucible, it emits red vapours, assumes the consistence of a jelly, and preserves this softness for a certain time. The nitrite of zinc is very deliquescent. The muriatic acid attacks zinc with effervescence. Hy- drogenous gas is produced, and biack flocks are precipi- tated, which some chemists have taken for sulphur, others for iron, and which Mr. De Lassone considers as an ir- reducible oxide of zinc. This evaporated solution be- comes thick, and refuses to crystallize. It suffers a very concentrated acid to escape when heated, and the muriate itself sublimes by distillation. The pure alkalis boiled on zinc obtain a yellow colour, and dissolve a part of the metal, as Mr. De Lassone has proved. Ammoniac digested in the cold upon this semi- metal, disengages hydrogenous gas: this evidently arises from the decomposition of the water, which alone, and without any mixture, is decomposed upon ignited zinc, as we have already observed. Zinc mixed with the nitrate of potash, and thrown into an ignited crucible, causes this salt to detonate btrongly. Zinc decomposes the muriate of ammoniac by simple trituration, according to Mr. Monnet. Pott has observed that a solution of alum, boiled upon the filings of zinc, is decomposed, and affords the sul- phate of zinc. Zinc fused with antimony, forms a hard and brittle alloy. It unites with tin and copper, and forms bronze; when combined with copper alone, it forms brass. It is mixed with gunpowder, \o produce the white and brilliant stars of artificial fire-works. It has been proposed to substitute this metal in the room of tin, for the internal lining of copper vessels; MANGANESE. 51 and it is ascertained 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 dissolve it, and that these salts are dangerous; but Mr. de la Planche has made all the experiments on this subject which his extensive knowledge and zeal for* the public good, could inspire; and he is convinced that the salts of zinc, taken in a more considerable dose tiian the aliments pre- pared in vessels tinned with this semimetal might con- tain, are not dangerous. The sublimed oxide of zinc is much employed by the German physicians under the name of Flowers of Zinc. This remedy is given as an antispasmodic. It may be administered in pills, in the dose of one grain. Tutty, or pompholix, is mixed with fresh butter, as an excellent remedy in disorders of the eyes. Mr. De Morveau has substituted the precipitate of zinc to white lead, in painting with the greatest advan- tage. It perfectly answers the intention of the artist, and is not attended with any dangerous consequen- ces in its use*. CHAPTER VII. Concerning Manganese. A MINERAL of a grey or blaqkish colour, soil- ing the fingers, and used in glass-houses under the name of Soap of the Glass-makers, has been long known in commerce. Most naturalists, such as Henc- kel, Cramer, Gellert, Cartheuser, and Wallerius, have placed it. among the iron ores. Pott and Cronstedt *did not consider it as a ferruginous substance. The lat- ter found it to contain tin; and Mr. Sage was long of opinion tiiat it was an intimate alloy of zinc and cobalt. * It will not answer in the place of white lead, as it does not dry so soon—Am. Ed. 52 ORES OF MANGANESE. The celebrated Bergmann, in the year 1764, declared in print, that black manganese ought to contain a pe- culiar metal; but he attempted in vain to extract it. However, Mr. Gahn, a physician at Stockholm, suc- ceeded in obtaining a metal by the assistance of an ex- ceedingly strong fire. We shall explain his process after having spoken of the different forms under which manganese is found in the earth. Manganese appears to be always found in the state of oxide; but this oxide exhibits several varieties. 1. It is sometimes grey, brilliant, -and crystallized, formed of very slender prisms confusedly intertwined, and resembling the ore of antimony ; from which how- ever it may be easily distinguished by exposing it upon charcoal. ' For antimony fuses, and affords vapours; but the manganese remains unchanged. The crystals of manganese are striated, tetrahedral, rhomboidal prisms, terminating in four-sided pyramids. They frequently diverge from a centre. 2. Manganese is very often black and friable. This species is found in the cavities of the brown haematites of the Pyrenean Mountains. I have discovered an ore at St. Jean de Gardonen- que, in the Cevennes. It is prodigiously light, is found in strata, and in pieces which almost always have the figure of an hexahedral prism, eighteen lines in length, and thirteen or fourteen in thickness. This ore, upon which I have made experiments that I shall presently recite, is the purest and finest I am acquainted with.* * Manganese of an excellent quality, is found in Northampton coun- ty, Pennsylvania. Its specific gravity at the temperature of 62° of Fahrenheit's thermometer, and before it had absorbed water was 3.4193. After (and the absorption accelerated by thirty minutes boiling in water) it rose to 3.7667. Two ounces of it reduced to powder, heated in an iron tube, in one \ of Lewis's black lead furnaces, yielded eighty cubic inches of oxigen- ous gas, which tested by phosphorus, in the eudiometer of Fontana, left behind about three per cent, of azotic gas. One measure of this oxigene gas, passed up over lime water, gave a portion of carbonate of lime, barely perceptible. One ounce measure of muriatic acid, heated upon one ounce by weight of it over water, afforded forty-five cubic inches of REDUCTION OF MANGANESE. 53 3. Manganese is sometimes of a reddish white colour, and composed of groups of protuberances. Its fracture is lamellated. That of Piedmont frequently has a grey, reddish tinge, and appears to be composed of small plates. It gives fire with the steel. The manganese of Macon in Burgundy is of a deeper grey, than that of Piedmont. That of Peregueux is intermixed with yellow martial ochre. It is found in separate bodies and not in veins like that of Piedmont. 4. Most of the white spathose iron ores contain man- ganese, and may be considered as ores of this semi-metal. Manganese is likewise mixed with calcareous spar, gypsum, jasper, haematites, &c. Mr. De la Peyrouse has described thirteen varieties of crystallized manganese found in the Pyrenean Mountains.—See the Journal de Physique, Jan. 1780, p. 67. 5. Scheele has proved that the ashes of vegetables contain manganese; and it is to this mineral that the colour of calcined potash is owing. To extract it, three parts of, fixed alkali, one of sifted ashes, and one- eighth of nitrate, must be fused together. The fluid mixture must then be poured into an iron mortar, where it congeals into a greenish mass. This being pounded, and boiled in pure water, must be filtrated, and saturated with sulphuric acid. At the end of a certain time, a brown powder is deposited, which possesses the proper- ties of manganese. To reduce manganese to the metallic state, a crucible is lined with charcoal; and into a hole made in this char- coal, a ball of manganese, previously kneaded with oil and gum ammoniac, is to be put; after which the hole is to be covered with powder of charcoal. Another cruci- ble must then be fitted on, and the vessels exposed to a violent fire for an hour and a half. By following this oximuriatic acid in which leaf copper, commonly called Dutch-me- tal, immediately inflamed. Like all the other ores of manganese, it is combined with iron, silecious earth, &c. A deep blue precipitate takes place, upon adding the prussiate of potash to a solution of it in the muriatic acid. Manganese is likewise found in the state of Virginia, and I have a specimen in my possession, picked up near Lancaster, Pennyslva- nia—Am. Ed, 54 REDUCTION OF MANGANESE. process, I have several times obtained the metal from the oxide of manganese of Cevennes. I have even suc- ceeded in reducing it, by simply putting the powder of manganese into a lined crucible. The button which is obtained almost always has aspe- rities on its surface. Globules appear which scarcely ad- here to the mass; and these portions are usually of a con- siderably deep green, while the internal part has a blueish cast. This metal is more infusible than iron. I have several times observed, when the fire has not been sufficiently strong to fuse the manganese, that several globules, of iron have appeared dispersed through the agglutinated oxide. Saline fluxes ought to be rejected, as insufficient for this reduction. The great disposition which this semi- metal has to become vitrified, causes it to be dispersed in the flux, where it remains suspended. I have several times, by using the vitreous flux of Mr. De Morveau, obtained metallic grains forming a button, or else dis- persed in the flux ; wrhich, when more narrowly examin- ed, proved to be nothing but iron, cobalt, or other me- tals, according to the nature of the ore of manganese. 1 have sometimes obtained even globules of lead; be- cause the coarsest glass in which the presence of that me- tal is the least suspected, and which enters into the com- position of the flux of Mr. De Morveau, contains it very often. The specific gravity of manganese has been estimated by Bergmann, in proportion to that of water, nearly as 6850 to 1000. The oxide of manganese, when strongly heated in close vessels, affords a prodigious quantity of oxigenous gas, and begins to afford it at a degree of heat less than is' ne- cessary to disengage it from the oxides of mercury: a strong fire is required to disengage the last portions. Four ounces of the manganese of Cevennes afforded me nine pints of oxigenous gas. Tjie residue in the retort wras a grey oxide ; one part of which was incrusted in the fused glass, and had communicated to it a very rich violet co- lour. PURE AIR FROM MANGANESE. 55 The oxide of manganese, distilled with charcoal, af- fords the carbonic acid :* but, if it be calcined in an open vessel, it is reduced into a grey powder, which loses con- siderably of its weight when the fire is very strong; and at length agglutinates, and forms a green mass. If it be mixed with charcoal, it does not suffer any perceptible change in its colour. Manganese, exposed to a very violent heat, vitrifies, and affords a glass of an obscure yellow colour. The iron which is mixed with it preserves its metallic form. Manganese is easily changed in the air, and is resolved into a brown powder of a greater weight than the semi- metal itself; a certain proof of oxidation. Manganese unites easily by fusion with all the metals except pure mercury. Copper alloyed with a certain quantity of manganese is still veiy malleable. If a mixture of the phosphate of urine with a small quantity of oxide of manganese be placed upon charcoal, and be kept in fusion for a few instants by means of the blue interior flame of the blowr-pipe, a transparent glass will be produced, of a blue colour inclining to red; which, when charged with a certain quantity of the salt, assumes the colour of a ruby. If it be kept in fusion for a longer time, a slight effervescence is perceived, and all the colour disappears. If the transparent .globule be then softened by the exterior flame, the colour soon re- turns, and may be again effaced by keeping up the fusion for a time. The smallest portion of nitrate, added to the glass, immediately restores the red colour; and, on the contrary, it is destroyed by the addition of sulphuric salts. This globule of glass, taken from the charcoal, and fused in the spoon of perfect metal, becomes red, and changes no more. These experiments were made by the cele- brated Bergmann. The sulphuric acid attacks manganese, and produces hydrogenous gas. This metal is dissolved more slowrly than iron ; a smell is disengaged similar to that which is afforded by the solution of iron by the muriatic acid. The solution is as colourless as water, and affords by evaporation transparent colourless crystals in the form of parallelopipeds, and of a bitter taste. Mr. Sage obtained * It yields carbonic acid gas and oxide of carbone.—Am. Ed. 56 EUDIOMETER WITH MANGANESE. them in tetrahedral prisms, terminated by four-sided py- ramids. This salt effloresces in the air. If rhe sulphuric acid be poured on the oxide of man- ganese, and its action assisted by a gentle heat, an asto- nishing quantity of oxigenous gas is disengaged. The oxide of manganese of Cevennes afforded me five pints and a half per ounce. When this oxide is deprived of its oxigene, the residue is a white powder, soluble in wa- ter, which by evaporation affords the sulphate of manga- nese, already described. The celebrated Bergmann has observed that coaly mat- ter, such as sugar, honey and gum, assisted the action of the acid. This depends on the combination of the oxi- gene with these agents, to form the carbonic acid; and the sulphuric acid acts more easily upon the metal itself. Manganese is precipitated from its solutions by the al- kalis, in the form of a whitish gelatinous matter; but this precipitate soon loses its colour, and becomes black by the contact of the air. This phenomenon, which I have myself been a witness to, can be attributed, in my opinion, only to the absorption of oxigenous gas: and I was convinced of this truth by agitating the precipitate in bottles filled with this gas; for in this situation the black colour is produced in one or two minutes, and a consi- derable part of the gas is absorbed. I have constructed an eudiometer as certain and as invariable as that which the liquid sulphure of potash, or solution of iiver of sul- phur, affords j but a large quantity of precipitate is re- quired, which must be agitated against the sides of the vessels, in order that it may present a greater surface to the air, and that the absorption may be more speedy. I judge of the absorption by causing the vessel to commu- nicate, by a graduated tube, with standing water. The ascension of this water in the tube is proportioned to, the volume of oxigenous gas absorbed. The nitric acid dissolves manganese with effervescence. There always remains a black, spongy, and friable body, which exhibited to Bergmann all the characters of molyb- * dena. Other solvents presented a similar residue. The solution of the nitrate of manganese has frequently a dull colour, and assumes the red colour with difficulty. This solution does not afford solid crystals, even by slow eva- poration. HABITUDES OF MANGANESE. 57 The oxides of manganese are soluble in the nitric acid. It is observable that this acid is not decomposed upon them, because it finds the metal in the state of oxide. Carbonic acid is afforded when coaly substances are ad- ded to assist the solution. When the nitrous or fuming nitric acid is used, the solution is made without the as- sistance of these coaly substances, because the excess of nitrous gas seizes the oxigene of the oxide. These so- lutions do not crystallize. The muriatic acid dissolves manganese; but when it is digested upon the oxide it seizes the oxigene, and passes in vapour through the water. This vapour is known by the name of Oxigenated Muriatic Acid, whose properties we have already explained. The residue in the retort consists of a portion of acid combined with the manganese. This by evaporation affords a , saline mass, which attracts the humidity of the air. The fluoric acid with manganese affords a salt of spar- ing solubility, and this acid dissolves but little of it: but by decomposing the sulphate, the nitrate, or the muriate of manganese by the fluate of ammoniac, a fluate of man- ganese is precipitated. The same phenomenon takes place with. the phosphoric acid. The acetous acid has but a weak action upon this substance. If it be digested upon the oxide of manganese, it acquires the property of dissolving copper, and forms the beautiful acetate of copper, or crystals of Venus; whereas the same acid, digested on copper, forms verdigris, or simply corrodes it. This circumstance proves that the acetous acid be- comes charged with oxigenous gas, by the assistance of which it dissolves the copper. The oxalic acid not only dissolves manganese, but likewise the black oxide of manganese. The satu- rated solution deposites a white powder, if there be not an excess of acid. This salt is blackened by the fire, but easily resumes the milky colour in the same acid. The oxalic acid precipitates it in the form of small crystalline grains, when poured into solutions made by the sulphuric, nitric or muriatic acids. The acidulous tartrite of potash dissolves the black oxide, even in the cold. The tartrite of potash added Vol. II. H 58 HABITUDES OF MANGANESE- to any solution whatever of manganese, occasions a pre- cipitate which is a true tartrite of manganese. The carbonic acid attacks manganese and the black oxide. The solution becomes covered in the open air with a pellicle, which consists of manganese that is separated and oxided. It is white when it does not. con- tain iron. If the muriate of ammoniac be distilled with this oxide of manganese, an elastic fluid is disengaged, according to the observation of Scheele, which he considers as one of the principles of ammoniac, without determin- ing its nature. Mr. Berthollet has proved that, when ammoniac is disengaged by a metallic oxide, there is a portion decomposed. The oxigene of the oxides unites to the hydrogenous gas of the alkali to form water, and the nitrogene gas escapes. Eight parts of oxided manganese take up, by a gen- tle heat, in a glass retort, three parts of sulphur; and produce a mass of a greenish yellow colour, which acids attack with an effervescence and hepatic smell. Manganese itself does not appear to combine with sulphur. In order to separate iron from manganese, the alloy must be dissolved in the nitric acid, and evaporated to dryness. The residue must be strongly calcined, and digested with weak nitric acid, and a small quantity of sugar. The acid takes up the manganese, which may be precipitated by the carbonate of potash. The alloy may likewise be put into a solution of the sulphate of iron. The acid abandons the iron to unite with the manganese. The iron having less affinity with the acid than the manganese, may likewise be precipitated by a few drops of alkali. The oxide of manganese, is chiefly used in glass- houses, to deprive glass of its green or yellow colour, which soda and sand, when fused together, usually as- sume. It has on this account been called the Soap of the Glass-makers. It is also used to colour glass and porcelain of a violet colour. CHARACTERS OF LEAD. 59 The consumption of diis mineral is become more con- siderable since the discovery of the oxigenated muriatic acid, which has pointed out its uses in bleaching of linen, cotton, &.c. CHAPTER VIII. Concerning Lead. LEAD is the softest, the least tenacious, the least sonorous, the least elastic, and one of the most ponderous, of metals. A cubic foot of lead weighs se- ven hundred and ninety-four pounds, ten ounces, four gross, forty-four grains. Its specific gravity is to that of water as 115523 to 10000. according to Brisson. Its fracture is of a blueish white colour, darker than that of tin, and tarnishing in the air. It possesses a peculiar smell, which is rendered perceptible by friction, A gentle heat is sufficient to fuse lead ; and the abbe Mongez obtained it in crystals of the form of quadran- gular pyramids, recumbent on one side. Some authors affirm that lead is occasionally met with in the na- tive state. Wallerius mentions thfee pieces of this kind. The German mineralogists likewise affirm that it has been found native in Villach in Carinthia. Mr. Genssane found in Vivarais, in four places, at Seremc- janes, at Fayet near Argentiere, at St. Etienne de Bou- logne, and near Villeneuve de Berg, "grains of native 'Mead, from the size of a chesnut to an almost impercep- " tible degree of smallness; they are all included in a very " ponderous metallic earth, which is precisely of the co- " lour of the ashes of beech, or of litharge reduced to " an impalpable powrder. This earth may be cut with a " knife, but requires the hammer to break it." He found pieces which contained a substance similar to litharge in their internal part, Linnseus speaks likewise of a native lead in crystals.— Most naturalists agree to consider native lead as of a very problematical existence. The various samples found in cabinets are probably owing to ancient mine works. Time 60 VARIOUS ORES OF LEAD. has changed their appearance, and incrusted them with various matters, which seem to prove that they do not owe their formation to the action of fire; and this is the circumstance which may have imposed on certain natu- ralists. 1. Lead is usually mineralized by sulphur; and this ore is known by the name of Galena.* It usually crystallizes in cubes, and in all the varieties of that figure. Galena is distinguished into several species. 1. Large diced galena. 2. Small diced galena. 3. Scaly or plated galena. 4. Compact galena, in small brilliant grains resembling steel. It does not appear to be lamel- lated. These distinctions are more especially necessary to be attended to, because the species are very different in rich- ness, and the alloy of silver, which is inseparable from galena. In general, the large diced galena is poor in sil- ver, and is used to give a glaze to pottery, by the name of Alquifoux, 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 of lead ore which is work- ed ; and we shall relate all we have to say concerning the working and assay of lead ores after having spoken of the other ores. 2. Lead has been found mineralized by the sulphuric acid. Mr. Monnet has called this ore the pyritous lead ore. It is friable, dull, black, and almost always crys- tallized in very long needles, or in stalactites. It efflores- ces in the air, and affords a true sulphate of lead. This appears to be of the nature of galena; for as die sulphate is not developed but by the efflorescence of the ore, it may be concluded that the sulphuric acid does not exist in the virgin ore itself. * Lead ore is found on the Great Kenhaway, opposite to the mouth of Cripple creek, in the county of Montgomery, in Virginia. Sixty tons of lead have been made at this place in one year. It is also met with on the Catawba lands, and in Pendleton district, South Carolina-; on Perkiomen creek about sixteen miles from Philadel- phia. One hundred weight of this lead, contains 2 and -i ounces of silver. The greatest lead mines in this country, are in Louisiana and on the Mississippi.—Am, Ed. VARIOUS ORES OF LEAD. 61 Lead mixed with iron is sometimes combined with the sulphuric acid. A large quantity is found in the island of Anglesea. It cannot be reduced upon charcoal with the blow-pipe, but it fuses into a black glass.—Dr. Winter- ing has indicated this ore. 3. The carbonic acid very often mineralizes lead, and exhibits some varieties which we shall proceed to de- scribe. A. The white lead ore.—This is almost always found in the cavities of decomposed galena, or in the veins of powdery stone containing galena. It is heavy, and frequently of a greasy colour; decrepitates in the fire; and is easily reduced by distillation, affording only water and the carbonic acid. Its form is almost always crystalline, but varies prodigiously. The primitive form appears to be a dodecahedron, with isosceles tri- angular planes. I have seen crystals accurately of the form of a hexa* deral prism sometimes terminated by a six-sided pyramid. The ores of St. Sauveur in the Cevennes have afforded us this variety; Mr. Sage possesses white lead ore of Ge- roldseck crystallized in cubes. White lead as transparent as flint glass has been found in England and in Siberia. The analysis of the white lead of Siberia afforded Mr. Macquart, per quintal, sixty-seven parts lead* twenty-four carbonic acid, six oxigene, and three water. B. Green lead ore.—This differs from the foregoing only in the modifications produced by the colouring prin- ciple, which is copper, according to Spielman; and iron, according to the greatest number of chemists. Its form is usually that of a truncated hexahedron; and this ore is not so easily reduced as the white ore. C. The black ore of lead.—Lead may return to the state of galena by resuming the sulphur it had lost; and this regeneration is not rare. It is enough that any he- patic vapour should strike the ore to effect this con- version. The ores of Tschopau in Saxony, and those of Huelgoet in Lower Britanny, exhibit fine instances of this phenomenon. 62 ASSAYING OF LEAD. The gradations or intermediate specimens of these different ores, establish an infinite number of species, which the naturalist can never admit but as varieties. The transition of the white lead ore to the black ore ex- hibits gradations of colour which it would be very super- fluous to describe. In the year 1766, Mr. Lehmann described a new spe- cies of lead ore, called Red Lead. It was found in Si- beria, in the environs of Catherineburg. Its crystals are grouped, and adherent to quartz, to copper ores, or iron; and sometimes to galena, with crystals of white and gr#en lead. It is frequently crystallized in rhom- boidal tetrahedral prisms, short, and truncated obli- quely. Mr. Sage has considered this lead ore as a variety of the preceding species, coloured by iron, of which Mr. Lehmann has proved the existence. The abbe Mongez thinks it is mineralized by the arsenical acid. Mr. Macquert has given us the most valuable informa- tion respecting the red lead ore ; and has proved by an accurate analysis that it contains, in the quintal, lead thir- ty-six, oxigene thirty-seven, iron twenty-five, and alu- mine two.* 4. The phosphoric acid has likewise been found natu- rally combined with lead. This ore, discovered by Gahn, owes its green colour to iron. It does not effervesce with acids. In order to assay it, it must be dissolved in the nitric acid by the assistance of heat, and the lead may then be precipitated by the sulphuric acid. The super- natant liquor being decanted off, and evaporated to dry- ness, affords the phosphoric acid: This ore melts by the blow-pipe, and affords an opaque globular mass without reduction. Its habitudes with fluxes resemble those of lead and its oxides. Mr. De la Metherie has informed us that Mr. * * *, an English gentleman, by treating lead ores with the blow-pipe, had observed that there was one whose glo- * Minium in a native state has been discovered by Mr. Smithson Tennant, in a vein of Galena, in Devonshire, England. A por- tion of this substance was found in the centre of a piece of cubic Galena, accompanied with crystals of spar—Am. Ed. TREATMENT OF LEAD AND ITS ORES. 63 bule crystallized by cooling, after having been in perfect fusion; and that these ores were not reducible by the blow-pipe. He suspected they were mineralized by the phosphoric acid. Mr. De la Metherie and this gentleman took seven ounces of the green lead ore of Hoffsgruard, near Fribourg in Brisgaw; which, when treated by the foregoing process, afforded them phosphoric acid. The phosphoric acid combined with minium afforded them a green compound. The decomposition of the ores which we have de- scribed frequently affords the oxides of lead, or calciform ores. These oxides at first afford a powder which, being car- ried along by waters, often mixes with argillaceous, cal- careous, or quartzose earths. These oxides vary more particularly in their colour, which assimilates them more or less perfectly to ceruse, massicot, or minium. In order to make the assay of a galena, it must be pul- verized and torrefied. The torrefied mineral, mixed with three parts of black flux, affords by fusion a metal- lic button, which indicates the proportions of the lead in the quintal of the ore. , Bergmann proposes to make the assay of sulphureous lead ores by the nitric acid, which dissolves the lead and not the sulphur. The solution is then to be precipitated by the carbonate of soda; and one hundred and thirty- two grains of the precipitate are equivalent to one hun- dred of the metal. If the ore contains silver, ammoniac is to be digested on the precipitate, from which it dis- solves the oxide of silver. The various operations to which lead ore is subjected to obtain the lead, are—1. It is sorted, to separate the rich or pure ore from the pulverized matter, and the gangue which contains no metal. 2. The ore is pulve- rized, and its gangue separated by washing. 3. The ore is roasted in a reverberatory furnace, wiii occasional agi- tation, that it may present all its surfaces to the air; and when the external part begins to assume the form of a paste, it is covered with charcoal, the mixture is stirred, and the heat increased. The lead then runs on all sides, and is collected at the bottom of the furnace, which is 64 MANUFACTURE OF RED LEAB. pierced, and permits the metal to flow into a receptacle properly defended by a lining of charcoal. The scoriae, which still retain much lead are fused by a blast furnace: the lead is cast into pigs for sale. To disengage the silver which the lead may contain, it is carried to the refining furnace ; where, by the united energy of fire, and die wind of bellows directed upon the melted lead, the metal is converted into a yellow scaly oxide, called Litharge. This litharge is driven off in proportion as it forms; and the silver remains alone in the middle of the cupel. The colour causes a distinction of the litharge into litharge of gold, or litharge of silver. When the litharge is fused in contact with charcoal, it re- sumes its state of metal; and the lead is so much the better, in proportion as it has been deprived of the silver it contained. The smallest alloy of fine metal renders it brittle. Lead is fusible by a gentle heat. If it be kept for some time in fusion, it becomes covered with a grey ox- ide ; which, when exposed to a more violent heat capa- ble of keeping it ignited, assumes a deep yellow colour, in which state it is called Massicot. Massicot may be converted into the red oxide, or minium, by the follow- ing process. When the lead is converted into massicot, 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 washed in water. The particles of lead which could not be pulverized in the mill, remain in the vessel where the washing is performed. This oxide of lead is spread out upon the hearth of the furnace in which it is calcined. Lines are drawn on its surface; and it is stined 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 sieves of wood, and passed through very fine net woik, or cloth of iron wire, placed over the casks which receive the minium. We are indebted to Messrs. Jars for this information, who have given Aery curious details respecting the manufactories 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 MANUFACTURE OF RED LEAD. 65 and twenty degrees of Reaumur's thermometer. But this heat is not adapted to works on a large scale; for in these the roof of the furnace is kept at a red heat. The lead increases in weight ten per cent, by the calcination. All these oxides, urged by a stronger heat, are con- verted into a yellow glass, so very fusible, that it pene- trates and destroys the best crucibles. It is used in glass- houses, on account of its fusibility, not only to assist the fusion, but likewise to render the glass softer, more pon- derous, of a more unctuous feel, and more susceptible of being cut and polished. These are the reasons for which it is made a part of the composition of flint glass, and crystal glass. The oxides of lead, distilled without addition, afford oxigenous gas by a violent heat.-—Priestley obtained it from minium, part of which was converted into globules of metal.* When these oxides are fused with coaly matter, the metal becomes revived. The sulphuric acid boiled upon lead affords much sul- phureous acid ; and an oxide is formed, which arises from a combination of the oxigene of the acid with the lead. A portion of the lead is nevertheless dissolved; for if a sufficient quantity of water be poured on the residue, a very caustic salt is obtained by evaporation, in tetrahedral prisms, soluble in eighteen times their weight of water. This sulphate is decomposed by fire, lime, the alkalis, &c. Very hot sulphureous acid, poured into a leaden ves- sel, corrodes and destroys it instantly. The concentrated nitric acid is readily decomposed upon lead, and converts it into a white oxide; but when the acid is weak it dissolves the metal, and forms crystals of an opaque white, in the form of segments of a three-sided prism. I have specimens of the nitrate of lead in my la- boratory, which possess the form of truncated hexahedral prisms; three of the sides being broader than the others, * The best method of procuring oxigenous gas from minium is to put it into a glass retort; cover it with sulphuric acid, and apply the heat of an Argand lamp. Oxigenous gas, obtained in this manner, is contaminated with carbonic acid gas and sulphureous gas, which may be separated from it by washing the airs in water.—Am, Ed, Vol. II. I 66 HABITUDES OF LEAD, &C~ and exactly similar to those which Mr. De Fourcroy ob tained by insensible evaporation. This salt decrepitates in the fire, and is fused with a yellowish flame upon ignited coals. The oxide of lead becomes yellow, and is reduced into globules of metal. Sulphuric acid takes lead from the nitric acid. The muriatic acid, assisted by heat, oxides lead, and dissolves a portion. This salt crystallizes in striated hex- ahedral prisms. This muriate is slightly deliquescent. Lime and alka- lis decompose it. The same acid poured on litharge decomposes it in- stantly. Fifty or sixty degrees of heat are produced. The solution affords fine octahedral crystals, of an opaque white colpur, a styptic taste, and of very considerable weight. This salt decrepitates on the coals ; and when the fire is increased, its water of crystallization escapes, and it becomes converted into a mass of a beautiful yellow co- lour. Three parts of water, at fifteen degrees of temperature dissolve one part; and boiling water more than its weight. The pure alkalis precipitate it in the form of a magma, which occasions a kind of miraculus mundi. The affinity of the muriatic acid with the oxide of lead is so strong, that it is capable of decomposing all its com- binations. Minium or litharge decomposes the muriate of ammoniac. The same oxides, triturated with marine salt, separate the soda; and it is upon these facts that Mr. Turner and others have established manufactories for procuring soda by the decomposition of marine salt.* The muriates of lead, calcined or fused, afford a pigment of a beautiful yellow colour. The manu- * I do not hear that soda has been separated from common salt by a method sufficiently cheap for the purposes of commerce. It is universally understood that Mr. Turner's profits arise from the sale of the combination of muriatic acid with the lead, which-forms the yellow pigment known in London by the name of Patent Yellow. It may be produced simply by the fusion of litharge and common salt; the alkali being volatilized, and driven off, if the fire be sufficiently intense. T. USES OF LEAD &0. 67 factories of soda have affored a very considerable quan- tity, which is substituted instead of the fine Naples yellow. 4>. The acetous acid corrodes lead; and affords a white oxide known by the name of white lead. To prepare this colour, the lead is melted, and cast into plates about half a line in thickness, four or five inches wide, and two feet long. These are rolled up in a spiral form, in such a manner that the revolutions remain at the distance of half an inch from each other. They are then placed in pots, upon three points, which project from the inside at about one third of the height. Malt vinegar is poured into these pots to the height of the bot- tom of the lead, and they are buried in dung beneath sheds. A great number of these are disposed beside each other, and several strata are formed. Care is taken to cover each pot with a plate of lead and boards. At the expiration of a month or six weeks they are taken out, and the white lead is separated. This white calx is then ground in mills, and afterwards put into a vat, from which it is taken out to dry. The drying is performed in the shade, because the sun impairs the colour. For this purpose it is put into small conical earthen pots; and when sufficiently dry it is wrapped in paper, and distributed for sale. Ceruse does not differ from white lead, excepting that a more or less considerable quantity of chalk is mixed with it. All the oxides of lead are soluble in vinegar. The so- lution of the acetate of lead, duly concentrated, crystal- lizes in efflorescent tetrahedral prisms; and forms the salt of saturn, or sugar of lead. Caustic alkalis dissolve the oxides of lead, and - the metal may be precipitated by the addition of acids. When the alkaline solution is concentrated, the lead re-appears nearly in the metallic form, and the alkali is found to have acquired a faint and very peculiar taste. The uses of lead in the arts are multifarious. It is used to make water pipes, boilers, coverings for the roofs of buildings, tea-chests, and other articles of package. It is rendered proper for these uses, either 68 USES OF LEAD, &C by laminating it, or by causing it to flow out upon a bed of sand well rammed and levelled, or upon the cloth cal- led ticking. It is likewise used to make bullets and small shot. The bullets are cast in moulds: but the small shot is made in the following manner:—Lead is fused with a small quantity of arsenic, to render it more brittle; and when its temperature is such as to admit of a card be- ing plunged in it without burning, it is poured into a kind of cullender, pierced at the bottom with many holes, and containing lighted charcoal; this cullender is held over water; and the lead assumes a round form as it enters this liquid. Lead is used in the tinning of copper vessels. This is a pernicious fraud supported by custom, and tolerated by the want of vigilance in the police. It is the more dan- gerous from the circumstance that fats, oils, and vinegar corrode or dissolve lead, which by that means becomes mixed with the aliments. Lead ore is likewise used to glaze pottery. For this purpose galena is pulverized, and mixed with water. The vessel intended to be glazed is dipped into this fluid, after having been exposed to a first baking. It accord- ingly becomes covered with the galena; which, when ex- posed to a violent heat, passes to the state of glass, and forms a covering of the glass of lead over the whole sur- face. This process is attended with the inconvenience of introducing a dangerous poison into our culinary ves- sels whose effects on the health of individuals cannot but be sensibly felt. Oxided lead enters into the composition of glasses, crystals, and enamels. It possesses the advantage of fa- cilitating the fusion, and giving the glass an unctuous feel, and a degree of softness, which renders it capable of be- ing cut and polished. White lead and ceruse are used by painters.* These * Cadet de Vaux has proposed to substitute the following compo- sition, in the place of white lead paint. Take of skimmed milk two quarts, fresh slacked lime six ounces and a half, linseed or nut oil four ounces, common whiting three pounds; put the lime into a stone ware vessel, and pour upon it a &uffi«ient quantity of milk to make a mixture resembling thin cream, USES OF LEAD, &C. 69 oxides possess the singular advantage of not being percep- tibly altered by their mixture with oil; and form, by their whiteness and body, a basis or receiver, which is very suitable for a variety of colours. The workmen who grind these colours are affected by them; and sooner or later become subject to the painters colic, colica pic- torum. Litharge is at present used to decompose sea salt; and the muriate of lead by fusion forms a superb yellow, very much employed in varnish colours. 8. Ceruse is likewise much used for drying up ha- bitual moisture of the skin, and for slight bums. It is applied to the skin in the form of powder, and there is no remedy more speedy. The salt of saturn, or sugar of lead, is almost entirely used by the calico printers. The vinegar of saturn, or the vegeto-mineral water of Mr. Goulard, is a very proper astringent in the con- sequences or remains of venereal disorders: it is like- wise used to wash burns and ulcers, and to facilitate their cure. This extract is likewise used to clarify liquors, and to deprive brandies of their colour; an evil practice which has been common for some years at Sette, though prohi- bited under heavy penalties.—The wine merchants avail then add the oil a little at a time, carefully stirring it to make it mix thoroughly ; the remainder of the milk is then to be added, and last of all the whiting is to be crumbled, and spread upon the surface of the fluid in which it gradually sinks; at this period it must be well stirred in, and the paint is fit for use. It is to be applied by a brush, in the usual manner, and in a few hours will become perfectly dry. Another coating may then be added, in the same manner as the former, and thus- the work is completed. This paint is said to possess great solidity, and a slight elasticity, which enables it to bear rubbing with a coarse woollen cloth, without being in the least degree injured. It has no smell. It is not black- ened by any vapours, and does not injure the health. For out door work, a much greater degree of solidity is given to the paint by increasing the proportion of lime to eight ounces and a half; of the oil six ounces, and adding two ounces of white Burgun- dy pitch. The pitch is to be melted by a gentle heat in the oil, and then added to the smooth mixture of milk and lime. Decade Pfdlo- tofihique, No. 29, year 9.—Am, Ed. 70 ORES OF TIN. themselves of this composition but too often, or of li- tharge, to render their sour wines sweet. This fraud was prodigiously common at Paris in the year 1750; and it was proved that, in the interval of three years, thirty thousand muids of vinegar had been thus sweetened; and sold for wine. The oxides of lead are likewise used to harden oils, or to render them more drying. In this operation the oxi- gene of the oxide combines with the oil, and causes it to approach nearer to the nature of resins. There is like- wise a solution of lead in oils, which serves as the basis of plasters. CHAPTER IX. Concerning Tin. TIN is a metal of a white colour, intermediate be- tween that of lead and silver. It is very flexible, and produces a crackling noise when bended. No other metal possesses this property except zinc, in which it is infinitely less-marked. , This metal is very soft, and the lightest of any of the entire metals. The specific gravity of fused tin is 7,2914, according to Brisson. A cubic foot of this metal weighs about five hundred and ten pounds. It is very ductile under the hammer; and its tenacity is such, that a wire one tenth of an inch in diameter is capable of supporting forty-nine pounds eight ounces without breaking. Mr. De la Chenaye has crys- tallized tin after several repeated fusions; he obtained by this means an assemblage of prisms united together side- ways. Tin has been found in the metallic state in the bowels of the earth. Mr. Sage possesses a specimen from the mines in Cornwall, and Mr. De Lisle likewise has one in his collection. This tin, so far from exhibiting any trace of fusion, has the external appearance of molybdena: it ORES OF TIN. 71 is easily broken; but the detached pieces may be flatten- ed by the hammer. Tin ore is either white or coloured. 1. The white tin ore, which has been often confound- ed with tungsten, crystallizes in octahedrons. Its texture is lamillated, and it frequently includes portions of red- dish tin ore. That of Cornwall afforded Mr. Sage sixty- four pounds of tin in the quintal. 2. The coloured tin ore does not differ from the pre- ceding, excepting that it contains iron, and sometimes cobalt. This ore usually has the form of irregular poly- hedrons. These ores afford carbonic acid by distillation when exposed to fire in a crucible. They decrepitate, lose somewhat of their colour, and become one-tenth less heavy. Bergmann found sulphureous tin among the minerals he received from Siberia. He affirms that this was of a golden colour externally, resembling aurum musivum; and internally it presented a mass of radiated, white, bril- liant, brittle crystals, which assumed changeable colours on exposure to the air. To assay a tin ore, nothing more is necessary than to fuse it in the midst of the coals. Calcination in the open fire dissipates much of the metal, according to the obser- vation of Cramer. In the working of tin ores, the mineral must be sorted very exactly; after which it is to be pulverized, and wash- ed upon tables covered with cloth. By agitation with a wisp or broom, the gangue is suspended or carried away ,by the water, and the tin ore remains alone. The furnace made use of in Saxony for the fusion of tin oie, is a variety of the blast furnace, on the hearth of which is a groove to receive the melted metal, and con- vey it into a bason; whence it is taken to be cast in moulds of copper or of iron. The tin ores of Cornwall are frequently mixed with copper, and arsenical pyrites. The quartz, which is its gangue, is very hard ; and on this account the operation is begun by torrefaction of the ore before it is pulverized. After the ore is washed, a separation of the magnetical 72 PUTTY AND OXIDES OF TIN. iron is effected by means of loadstones. The ore is usu- ally fused in the reverberatory furnace. In Saxony, and in England, the scoriae are three times fused to separate the tin, after which they are pounded to separate the last portions of metal. As the vein of tin in the mines of Cornwall is always mixed or accompanied with a vein of copper, the tin must contain this latter me- tal, however great the precautions which may be attended to in the working. We are acquainted witii three kinds of tin in com- merce. 1. Pure tin, such as that of Malacca, of Banca, and the soft tin of England. The tin of Malacca is cast into moulds, which give it the form of a quadrangular trun- cated pyramid, with a small rim at its base. It is called, in France, Etain en Chapeau, or en Ecritoire. Each ingot weighs one pound.—The tin of Banca is in the form of oblong ingots, weighing from forty to forty-five pounds each. 2. The English tin, in large pigs, is cast into sticks of ten or twelve lines in diameter, and a foot and a half long. 3. The tin of the pewterers is alloyed with various metals. The law in France permits them to add copper and bismuth; and they of their own authority add zinc, lead, and antimony. Every kind of tin enters into fusion with considerable facility, for it is the most fusible of the metals. If it be kept in fusion for a short time, exposed to the action of the air, the surface becomes wrinkled, and covered with a grey pellicle. If this first covering be taken off, the tin appears with all its brilliancy ; but soon becomes dull, and is oxided again. Tin gains one tenth of its weight, by this calcination. When the oxide is white, it is then called Putty. It is this oxide of tin which the makers of pewter spoons, who usually travel over the country, call the Dross of Tin. They are very careful to scum the metal as often as possible, to clear it of the dross; and by this means they avoid giving the peasant any more of his old pewter than that which they cannot contrive to take away from him. They are very well acquainted with the art of fusing this pretended dross into good tin, by heating it in contact with charcoal. PUTTY AND OXIDES OF TIN. . 73 The putty of tin is used to polish hard bodies ; and to render glass opaque, which converts it into enamel. Tin takes fire by a violent heat, according to Geoffroy; and a white, oxide sublimes, while part of the tin is converted into a glass of a hyacinthine colour. If tin be kept in fusion in a lined crucible, and the sur- face 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 several other metals, may acquire a brilliancy they do not usually possess, by pouring them out at the moment before they would congeal in the crucible. This treatment secures them from the oxidation they suffer in cooling, when they are poured out too hot; and by this method, which is very simple, I have procured to tin and lead a degree of brilliancy which they would hardly be thought capable of exhibiting. Tin, distilled in close vessels, affords a white sublimate in the neck of the retort, which Margraff took for arse- nic ; but Messrs. Bayen and Charlard have proved that it was not that substance. The action of acids upon tin varies according to the degree of purity of the metal. The sulphuric acid of commerce dissolves tin, by the assistance of heat; but part of the acid is decomposed, and flies off in the form of very penetrating sulphureous acid. Water alone precipitates this oxided metal. Mr. Monnet has obtained crystals by calcination, which re- semble fine needles, interlaced among each other. The sulphuric acid dissolves the oxide of tin much better. The nitric acid devours tin. The decomposition of • this solvent is so speedy, that the metal is seen to be pre- cipitated, almost instantly, in a white oxide. If this acid be loaded with all the tin it is capable of calcining, and the oxide be washed with a considerable quantity of dis- tilled water, a salt may be obtained by evaporation, which detonates alone in a crucible well heated, and which burns with a white and thick flame, like that of phosphorus. The nitrate of tin, distilled in a retort, swells up, boils, and fills the receiver with a white and thick vapour, which lias the smell of nitric acid. Vol. II. K 74 FUMING LIQJ7QR OF LIBAVIUS. Mr. Baume even pretends that the nitric acid does not dissolve tin; but Kunckel, and the famous Rouelle, have maintained the contrary. Messrs. Bi yen and Charlard dissolved five grains in two gross of pure nitric acid, di- luted with four gross of distilled water.* The muriatic acid dissolves tin, whether cold or heated. During the effervescence, a very fetid gas is disengaged. The solution is yellowish, and affords needle-form cry- stals bv evaporation, which attracts the humidity of the air. Air. Baume prepared this salt in the large way for the calico printers. Out of twelve pounds of tin, dissolv- ed in forty-eight pounds of acid, he had a residue of two ounces six gross of a grey and soluble powder, which Margraff had taken for arsenic. Mr. Baume has ob- served that the crystals of the muriate of tin differ ac- cording to the state of the acid. He obtained crystals, similar to those of the sulphate of soda, in needles, or in scales like those of the acid of borax. Mr. Monnet as- serts that he obtained, by the distillation of a muriate of tin, a fat matter, a true butter of tin, and a liquor resem- bling that of Libavius. The ox igenated muriatic acid dissolves tin speedily; and the salt which it produces, possesses all the characters of the ordinary muriate, according to Mr. De Fourcroy. That which is known by the name of the Fuming Li- quor of Libavius, appeal's to me to be a muriate of tin, in which the acid is in the state of the oxigenated muri- atic 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 corrosive sublimate. The whole is then introduced into a retort, a receiver * The nitric acid, when pure and concentrated, has no action on tin, but if water be added to the mixture, it is decomposed, and ni- trous oxide, nitrous air, nitrate of ammoniac, and oxide and nitrate of tin are formed. In this case, part of the oxigene of the water and nitric acid, unite to the tin, and form a white oxide, a portion of which is dissolved by the add, and nitrate of tin is made. Another part of ti;e oxigene of the acid and water, joins some of the azote of tiie acid, generating nitrous oxide and nitrous air. The hydrogene of the water, combines with another portion of the azote of the acid, and forms ammoniac, which unites to the acid, and makes nitrate of ammoniac. This gas may be set at liberty, by putting potash or lime in the vessel in which the experiment is made.—Am. Ed. * SCARLET COMPOSITION. 75 adapted, and distillation proceeded upon by a gentle heat. An insipid liquor passes over first, which is followed by a sudden eruption of white vapours, which condense into a transparent liquor, that emits a considerable quantity of vapours by mere exposure to the air. The residue in the retort, for an analysis of which we are indebted to Mr. Rouelle the younger, consists of a slight lining in the neck of the retort, which contains a small quantity of the fuming liquor, some muriate of tin, muriate of mercury, and running mercury. The bottom of the vessel con- tains an amalgam of tin and mercury ; above which lies a muriate of tin of a grey white, solid and compact, and which may be volatilized by a strong heat. The nitro-muriatic acid dissolves tin with vehemence : a violent heat is excited ; and it frequently happens that a magma is obtained resembling pitch, which becomes har- der in process of time. This happens when the very concentrated acid has dissolved too much of the metal; and these inconveniences may be obviated by adding wa- ter in proportion as the solution proceeds. The solution of tin which constitutes the composition for scarlet, is made with the common aqua-fortis, pre- pared with saltpetre of the first boiling. This is a kind of nitro-muriatic acid, which unfortunately varies in its properties, according to the two variable proportions of muriate of soda and nitrate of potash. For this reason, the dyefs are continually making complaints, either that the aqua fortis precipitates, which happens when it con- tains too small a quantity of muriatic acid; or that it af- fords an obscure colour, which depends on an excess of the same acid. The first inconvenience is remedied by dissolving sea salt, or sal ammoniac, in the aqua-fortis; and the second by adding saltpetre. The most accurate proportions to make a good solvent for tin, are, two parts of nitric acid, and one of muria- tic acid. Tin is likewise soluble in the Vegetable acids. Mr. Schultz, in his Dissertation De Morte in Olla, has de- monstrated die solubility of this metal in acids. Vinegar corrodes it by a gentle heat, according to the experiments of Margraff. 76 ALLOYS OF TIN. Most of the tin in commerce is alloyed with various metals. That of England contains copper and arsenic artificiallv, according to Geoffroy; and naturally, accord- ' ing to the Baron Dietrich, Sage, &c. The tin of the plumbers or pewterers, called Pewter, contains several metals. The ordonnance in France permits them to add a small quantity of copper and bismuth. The first me- tal renders it hard; and the latter restores the brightness which would else have been impaired by the copper, and renders it more sonorous. The pewterers take upon themselves to add antimony, zinc, and lead ; the antimo- ny hardens it, the zinc renders it whiter, and the lead di- minishes its value. It is a desirable circumstance to possess the means of ascertaining the nature and propor- tions of these alloys. We are indebted for the following processes to Messrs. Bayen and Charlard. A. When tin contains arsenic, the solution in the mu- riatic acid exhibits a black powder, which consists of ar- senic separated from the tin. This method is capable of rendering the two thousand and forty-second part of alloy perceptible. B. If the tin contains copper, the muriatic acid, which attacks tin with facility, precipitates the copper in the form of a grey powder, provided there be no excess of acid, and the solution be made without heat. The cop- per is likewise precipitated by a plate of tin immersed in the solution. t C. Bismuth is shewn by the same process as the copper. D. To ascertain the mixture of lead, the nitric acid must be used, which corrodes the tin, and dissolves the lead. The pewterers have two methods of assaying this metal. 1. The assay of the stone, which consists in pouring it into a hemispherical cavity made in a calcareous stone, and terminating in a channel or groove. The workman attentively observes the phenomena of its cooling; and from these circumstances, as well as from the crackling or noise which the tail of the assay affords when bended, he judges of the purity of the metal. AURUM MUSIVUM. 77 2. The assay by the ball consists merely in a comparison of the weight of pure tin with that of adulterated or al- loyed tin, poured into the same mould. It cannot but be immediately perceived that these me- thods are very imperfect. The various metals which are prejudicial to health, are not added to the tin in a sufficiently great proportion to produce any dangerous effects. It seems that Margraff wras deceived by some foreign circumstance, when he affirmed that the tin of Morlaix contains thirty-six grains of arsenic in the half ounce; for this quantity is more than sufficient to render the metal as brittle as zinc. Messrs. Bayen and Charlard found no arsenic in the tin of Banca and of Malacca. The tin of England never contains more than three-fourths of a grain of arsenic in the ounce of metal; and supposing this to be the maximum, the daily use of tin cannot be dangerous; since a plate in which arsenic existed in this proportion, lost no more than three grains per month by constant use, which amounts to the five thousand seven hundred and sixtieth part of a grain of arsenic lost daily. The expe- riments which these two skilful chemists have made upon animals, by mixing arsenic in larger proportions with tin, are sufficient to remove every apprehension concerning the use of this metal. The lead alone may be productive of dangerous conse- quences, because the pewterers add it in a very conside- rable proportion. The combination of tin with sulphur forms aurum mu- sivum, or mosaic gold. The process for making it which has best succeeded in my hands, is that described by the Marquis de Bullion. It consists in forming an amalgam of eight ounces of tin and eight ounces of mer- cury. For this purpose, a copper mortar is heated, and mercury poured into it; and when it has acquired a cer- tain degree of heat, the melted tin is poured in, and the mixture agitated and triturated till cold. Six ounces of sulphur, and four ounces of sal ammoniac, are then mixed; and the whole put into a matrass, which is to be placed on a sand bath, and heated to such a degree as to cause a faint ignition in the bottom of the matrass. The fire must be kept up for three hours. The aurum musivum 78 AMALGAM. thus obtained is usually beautiful: but if, instead of placing the matrass on the sand, it be immediately exposed upon the coals, and strongly and suddenly heated, the mixture will take fire, and a sublimate will be formed in the neck of the vessel, wiiich consists of the most beautiful aurum musivum. I have obtained it by this process of a dazzling colour in large hexagonal scales. The mercury and the sal ammoniac are not in strict- ness necessary to the production of aurum musivum. Eight ounces of tin dissolved in the muriatic acid, preci- pitated by the carbonate of soda, and mixed with four ounces of sulphur, produced the Marquis of Bullion a fire aurum musivum : but this is not capable of increas- ing the effects of the electrical machine, which proves that the composition owes its virtue in that respect to the mercury it contains in the proportion of six to one, when prepared in the former process. This preparation is used to give a beautiful colour to bronze, and to increase the effects of the electrical machine by rubbing the cushions. The Baron Kienmayer has described the following amalgam, composed of two parts of mercury, one of zinc, and one of tin:—The zinc and the tin are to be fused, and mixed together with the mercury; and the mixture agitated in a wooden box, internally rubbed with chalk. The mass is then to be reduced to a fine powder; and employed in that state, or mixed with grease. The effect of this amalgam is surprising; for by this means the power of electrical machines is inconceivably augmented. The amalgam of tin is capable of crystallization. Mr. Sage's process consists in pouring two ounces of 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 sand bath. No mercury was disen- gaged; but the tin was found in a crystallized state above the mercury which had not entered into combination. The lower part of tiiis amalgam is composed of grey brilliant crystals in square plates, thin towards their edges, having polygonal cavities between each. Every ounce of tin retains in its crystallization three ounces of mer- cury. CHARACTERS OF IRON. 79 The amalgam of tin is used to silver looking-glasses. For this purpose, a leaf of tin is spread out upon a table of the size of the glass, mercury is poured upon it, and spread about with a brush. This being done, a larger quantity of mercury is poured upon the tin, so as to form a covering of more than one line in thickness. The glass is slided upon this covering, by presenting one of its edges; taking care at the same time that its surface shall be beneath the level of the mercury, in order that the impurities which might hinder a perfect contact may be driven before it. The plate of glass is then loaded with weights equally distributed over its whole surface; by which means all the excess of mercury is pressed out, and flows away through channels made in the edges of the table. The air being driven out from between the amalgam of tin^md the glass by this strong compression. serves greatly to render the amalgam adherent. Several days ate required to elapse before it be sufficiently dry to admk of removing the glass. Tin alloyed with copper forms bronze, or bell-metal. Seven parts of bismuth, five of lead, and three of tin, form an alloy which liquefies in boiling water. CHAPTER X. Concerning Iron. IRON is the most generally diffused metal in nature. Almost every mineral substance of this globe is colour- ed with it; and its various alterations produce that truly astonishing variety of colours which are comprehended betw een the blue and the deepest red. This metal like- wise exists in the vegetable kingdom, where it consti- tutes an almost inseparable principle. It even appears to be one of the products of organization, or vegetation; for it is found in vegetables which are supported merelv 8Q NATIVE IR0.N. by air or water. It is indeed control}- to sound philosophy to suppose that all the iron with which earths are impreg- nated, must arise from the wearing of plough-shares: for, not to mention that the plough has not passed every- where, we see iron daily formed in vegetables. There is no reason to fear diat the metal should on this account be- come too abundant; because it is continually destroyed by passing to the state of oxide. " If on the other hand, we cast our attention towards the infinite number of uses to which this metal is appli- ed in society, we shall perceive that it is perhaps the most essential to be known, because it is the most diffused, the most useful, and the most employed. This metal is of a white livid colour, inclining to grey, obedient to the magnet, and gives fire with quartz ; which last circumstance is attributed to the fusion and rapid combustion of particles of the metal detached by the stroke. It is the lightest of all metals except tin. One cubic foot of forged iron weighs five hundred and forty- five pounds. The specific gravity of fused iron is 7,2070. —See Brisson. Iron is very hard, susceptible of a fine polish, and Aery difficult of fusion. It may be drawrn into very fine wire, of which the strings of the harpsichord are made. It be- comes hard by hammering, without heat; but when as- sisted by heat, it may be hammered into every imagina- ble form. Iron is universally dispersed; but, by common con- sent, those places, or matrices, in which the iron is suf- ficiently abundant to be wrought with profit, are called Iron Mines, or Ores. Iron is found native, without mixture, in several places. We shall not here mention those ridiculous assertions, which have no other merit than that of having been au- thorized by the suffrages of certain celebrated men.— " Albertus Magnus decidisse coelum, imbre, massam ferri centum librarum. Petermannus, magna tempestate, cum projectu multorum lapidum, coelo molem ferri deci- disse, qua? in longitudine sexdecim, in latitudine quinde- cim in crassitie duos, pedes habuerit:" that is, of the weight of forty-eight thousand pounds, and containing NATIVE IRON. 81 four hundred and eighty cubic feet.—Becher supplem. in Phys. Subtcr. cap. iii. p. 599.* We are indebted to Lehman for a description of a piece of native iron possessed by Margraff, which came from Eibenstock in Saxony. . The grain was distinguishable on both sides. Henckel possessed a small piece incrusted with a yel- low earth; and the cabinet of the Royal School of mines possesses one which is covered with spathose iron ore. A- danson and Wallerius affirm that it is found in Senegal; and Rouelle received a piece from thence which was very malleable. Simon Pallas speaks of a mass of native iron found near the great river Jenesci in Siberia. This iron is a very spongy, very pure, perfectly flexible, and pro- per to be formed into instruments by a moderate fire. It is naturally incrusted with a kind of varnish which pre- serves it from rust. Mr. Macquart doubts the legitimacy of the native iron, described by Pallas : he thinks that it may be considered as fused iron. Mr. De Morveau does not believe in the existence of native iron. Though some doubts may be raised concerning the le- gitimacy of these pieces, and there may be reasons to consider some of them as consequences of the action of * A number of stones, composedof iron, silex, magnesia, and nick- el, have fallen upon the earth in different parts of the world. Their origin is unknown. ✓ They have been considered as productions thrown on the earth, by volcanos or hurricanes; as mineral substances, fused by light- ning ; as concretions in the atmosphere ;' and as masses, foreign to our planet. One of these stones fell at Creon, in the parish of Juliac, on the 24th of July, 1790, about nine in the evening. It appeared as a very bright fire ball, the light of which was as pure as that of the sun ; it had the size of a common air balloon, and was long enough visible to throw the inhabitants into the greatest consternation, after which it burst, and disappeared. A few days af- ter this, some peasants brought stones, which they said were the re- sult of the fall of the meteor. The opinion, says '> 'auquelin, which makes them come from the moon, however extraordinary it may appear, is perhaps the least improbable, and if it be true, that no direct proofs can be given of this opinion, it is equally certain, that no well founded reasoning can be opposed to it.—Am. Ed. Vol. II. L The follotving Table will shew in what part of the World, the Stones have fallen. Substances 120 lb. Shower of stones Shower of stones ShoWer of iron Shower of mercury A very large stone Three large stones Shower of fire Stone of 72 lbs. About 1200 stones—one of Another of 60 pounds A stone of 59 pounds Shower of sand for 15 hours Shower of sulphur Sulphureous rain - The same - - - Shower of sulphur Ditto of a vifcid unknown matter Two large stones weighing 20 lbs. A stony mass ...... A stone of 76 lbs. --..-. A stone - - - . - - - - ■ A stone -----.--. Extenfive shower of stones • - About 12 stones ------ A large stone of 56 lbs- - - - . A stone of about 20 lbs. - » - - A stone of 10 lbs. ----.. Shower of stones ------ Shower of stones ---.-. Mass of iron 70 cubic feet - - - Mass of ditto, 14 quintals - - - Shower of stones ------ Large stone, 260 lbs. - - - - Two stones, 200 and 300 lbs. - - A stone of 20 lbs. ------ Several ditto from 10 to 17 lb*. Places .-where they fell. At Rome....... At Rome ------ In Lucania - - - - - In Italy - .... Near the river Negos, Thrace In Thrace..... At Quesnoy - - - - - Near Larissa, Macedonia - Near Padua in Italy - . On Mount Va-ier, Provence In the Atlantic - - - - Sodom and Gomorra - - In the dutchy of Mansfield • Copenhagen - - - Brunswick - . - - Ireland - - - - - Liponas in Brese - - Niort, Normandy - - At Luce in Le Maine At Aire in Artois - In De Cotentin - - - Environs of Angen - Sienna, Tuscany - - Wold Cottage, Yorkshire - . Sale, department of the Rhone - In Portugal -•--.- Benares, East Indies - - - - At Plann, near Tabor, Bohemia America - • -..... Abakank, Siberia..... Barboutan, near Roquefort • " Ensisheim, Upper Rhine - - Near Verona ------ Sales, near Ville Franche Near X/Aigle, Normandy Period of their Fall. Under Tullus Hostilius - - - - - Consuls C. Martius & M. Torquatus Year before the defeat of Crassus Second year of the 78 Olympaid Year before J. C. 452 - - - Jan. 4th, 1717..... Jan. 1706 ------ In 1510 ------- Nov. 27th, 1627 - April 6th, 1719. - In 1658 - - - In 1646 - - - Oct. 1721 - - In 1695 - - - Sept 1753 - - ■ In 175O - - - • Sept. 13th, 1768 - In 1768 - - - - In 1768 - - - ■ July 24th, 1790 July 1794 - " - DrC. 13th, 1795 - March 17th, 1798 Feb.19th, 1796 - Dec. 19th, 1798 July 3d, 1755 \pril 5th, 1800 - Very old - - - July 1789 - . . Nov. 7th, 1492 In 1762 March 12th, 1798 April 26th, 1803 - Testimonies. Livy J. Obsequens Pliny Dion Pliny Ch. of count Marcellin. Geoffroy le Cadet Paul Lucas Cardan,Varcit Gassendi Pere la Feuillee Moses- Spangenberg Olaus Wurmius Siegesber Muschembroek Delalande Delalande Bachelay Gurson de Boyaval Morand St. Amand, Baudin, &C. Earl of Bristol Capt. Topham Lelievre and De Dree Southey J. Lloyd Williams, esq. B.de Born Philosophical Magazine Pallas, Chladni, &c. Parcel jun. Lomet, &c. Butenschcen \rad. de Bourd- Du Dree Fourcroy. Am. £J. CO to ORES OT IRON. 83 lire, we cannot however refuse to admit of the existence of native iron, after the depositions, facts, and attestations which present themselves on all sides in support of this truth. Iron, slowly cooled, crystallizes in octahedrons almost always implanted one in the other. We are indebted to Mr. Grignon for this observation. I am in possession of a piece of iron entirely covered with small tetrahedral, flat, and truncated pyramids. Some of the pyramids have a base of one line in breadth. It comes from the fron- tiers of the Comte de Foix. This iron is very seldom found unaltered by foreign admixtures ; but I think we may consider all the iron ores which are attracted by the magnet, as containing the native metal, dispersed in some gangue : and we shall attend to these species before we treat of the oxides and martial salts. ARTICLE I. Concerning Iron Ores which are attracted by the Mag- net. 1. The octahedral iron ore.—This ore has the form of octahedrons, isolated, and dispersed in a gangue of schis- tus, or calcareous stone. The crystals are grey, very re- gular in their form, and strongly bedded in the stone. Their size is from half a line to six or seven in diameter. Corsica and Sweden afford this kind. Mr. Sage observes that octahedral crystals of iron are sometimes found in the finest white marble of Carara. The black ferruginous sand which accompanies the hya- cinths in the brook of Expailly, is an octahedral iron ore, obedient to the magnet. 2. Iron ore in small plates or scales.—The small plates or scales which are attracted by the magnet, and are found in most rivers which contain gold, are an iron ore, nearly in the metallic state. This sand forms the residue which is left after the precious metal has been taken up by amal- gamation. It is mixed with fragments of quartz, garnets, &c. I found a large quantity in the sand of the river of Ceze: it was also sent me from the neighbourhood of 84 IRON ORES. THE MAGNET. Nantz. I have received some likewise from Spain ; and this sand has afforded me certain phenomena which ap- pear to entitle it to a particular rank among the metals. Acids dissoive it by the assistance of heat; and always without effervescence, or the disengagement of gas. It communicates the same colour to the nitro-muriatic acid as piaima does. It is indecomposable by heat, either in the open fire, or in open vessels. I have endeavoured to re- duce it by all the known fluxes, but in vain. It precipi- tates in the flux, mixes with it, and recovers its form and magnetic virtue by pulverizing the mass. It possesses several characters of the siderite, or phosphate of iron. 3. Iron dispersed in stones renders them obedient to the magnet. The ophites, the serpentines, the micas, the pot-scones, and several marbles, are in this situation. Iron disseminated in a gangue of qiuirtz, or very hard jasper, forms emc?.y, which on account of its hardness is used to grind and polish glass. It comes to us from Jersey and Guernsey, where it is plentifully found. The magnet itself is nothing else but the iron we speak of, modified in such a maimer as to afford a passage to the magnetic fluid, and to exhibit the known phenomena. The magnet is sometimes found in a regular form. Mr. Sage affirms that he possesses a small piece of magnet from St. Domingo, on which octahedrons are distinguish- able. We have likewise read, in the General History of Voyages, that at twenty leagues from Solikamskai in Si- beria magnets are found of a cubical form i id greenish colour, of a lively brilliant appearance, which are redu- cible into glittering scales by pulverizing. The magnet varies in its quantity of metal. Those of Sweden and Siberia are very rich in iron; but the mag- netic force is not in proportion to the iron they contain. There is reason to think that the magnetic agent is a modification of the electric power. 1. Iron which re- mains a long time in an elevated position becomes mag- netic. 2. Instruments of iron struck with lightning are usually magnetized. 3. Two pieces of iron may be magnetized by rubbing them against each other in the same direction. 4. Black iron ores are found in Sweden which are attracted by the magnet, and whose metallic particles are sometimes so weakly connected together that VARIOUS IRON ORES. 85 they are reducible into powder. We have several species of these ores in Languedoc. This species is in general very rich, and affords near eight} pounds of iron per quintal. 5. iron appeal's to exist in the metallic state in some other species, such as the specular iron ore. But the me- tallic state is less evident and characteristic, the metallic qualities being more changed; and these ores are less at- tracted by the magnet. These iron ores frequently exhibit metallic plates of a brilliancy equal to that of steel, and unalterable in the air. The ore of Mont d'Or, that of Framont in the principal- ity of Salm, and those of the mountains of Vosges, have alibrded us very curious specimens. These plates are sometimes hexagonal, formed by two hexahedral pyra- mids truncated near their base. The specular iron ore of Framont afforded Mr. Sage lift} -two pounds of iron in the quintal: the iron is very ductile, and acquires much fibre. The celebrated iron ore of the island of Elbe is of this kind, but it has not the plated form. Its crystals are len- ticular, with brilliant facets, which are dodecahedrons with triangular planes. These beautiful groupes of cry- stals are sometimes shaded with the most lively colours. White clay, rock crystal, cupreous pyrites, &c. are found among them. The Lucquese work this ore in the Catalan method, by stratifying charcoal and the ore, one layer over the other. The fire is kept up by good bellows ; and when all the coal is consumed, the iron is found collected toee- ther in a mass, which is carried to the hammer. The eisenman is a scaly specular ore. When it is rub- bed, brilliant particles are detached from it; which has caused the miners of Dauphiny to give it the name of Luisard. * The eisenman is an iron ore of a brilliant red colour, which contains plumbago and iron.* * Iron mines are numerous in the United States. The toughness of some of the cast iron made in Virginia, says Mr. Jefferson, is very remarkable. Pots and other utensils of this iron, cast thinner than usual, may be safely thrown into and out of waggons, in which they are transported. 86 DECOMPOSITION OF PYRITES. ARTICLE II. Concerning Sulphureous Iron Ores, or the Sulphures of Iron. The union or combination of iron and sulphur forms the sulphureous iron ore, martial pyrites, sulphure of iron, &c. These sulphures are very abundant, and are evi- dently formed by the decomposition of vegetables. I have several times found pieces of wood buried in the earth perfectly incrusted with pyrites. The effect of sub- terraneous fires is owing only to the mixture of these sul- phures with the remains of vegetables. Those species of coal which effloresce in the air, owe their decomposition only to the pyrites with which they are penetrated. It is likewise to the decomposition of the pyrites that we must refer the heat of most mineral waters. The sulphure of iron sometimes crystallizes in cubes, and often in octahe- drons. The union of a number of octahedral pyramids with their points towards a common centre, forms the globular pyrites. When the sulphur is dissipated, it sometimes happens that the pyrites loses neither its form nor its weight. It then becomes brown, is attracted by the magnet, and is called the Brown or Hepatic Iron Ore.—See De Lisle. But the decomposition of pyrites most commonly pro- duces the sulphuric acid, which seizes the iron, dissolves it, and forms an efflorescence on the surface. Advantage has even been taken of this property of the pyrites to establish manufactories of sulphate of iron, or copperas. The two valuable establishments which have been made of this kind, in the vicinity of Alais, work certain strata of a hard ponderous pyrites. These are formed into heaps upon areas, where the ground is slightly inclined. The efflorescence is accelerated by watering the pyrites, grossly broken, with water. This fluid dissolves all the salt Salt pans made of it, and no longer wanted for the purpose of making salt, cannot be broken up, in order to be melted again, un- less previously drilled in many parts.—Am. Ed. SULPHATE OF IRON. 87 which is formed, and carries it into reservoirs, where the solution suffers all the foreign matters it may contain to subside. It is left at rest in these reservoirs, in which the sun produces a slight concentration of the fluid ; and the concluding evaporation is made in leaden cauldrons with the addition of old iron, to saturate the acid with as much of that metal as possible. The crystallization is performed in basons, in which pieces of wood are dispos- ed to assist the formation of crystals. These two manu- factories in Languedoc are capable in their present state, of furnishing upwards of forty thousand quintals of "cop- peras, if the demand required it. In order to facilitate the vitriolization, it is necessary to e-ive access to the air, because the concurrence of this element is necessary to form the sulphuric acid.. The sulphate of iron crystallizes in rhomboids.* It effloresces in the air, and gradually loses its fine green colour by the dissipation of its water of crystalli- zation. If the sulphate of iron be exposed to heat, it lique- fies, boils, becomes thick, and is reduced into powder. This powder, mixed with pulverized nut galls, forms a dry ink, which several persons sell as a secret, and * The green vitriol or copperas of the shops contains two salts, known by the names of the sulphate and oxy-sulphate of iron. The oxy-sulphate may be formed by exposing a solution of sul- phate of iron, to the open air, or by pouring into it nitric acid, and applying heat The salt is of a red colour, and will not crystal- lize. It deliquesces when exposed to the action of atmospheric air, and is soluble in water and alkohol. It may be separated from green vitriol by alkohol. When the gallic acid is added to a solution of the oxy-sulphate of iron, it strikes a deep black colour, but produces no effect on a solution of the sul- phate of iron. Both these salts absorb nitrous gas. Many bodies Jiave the property of depriving the oxy-sulphate of iron, of its excess of oxigen, and of converting it into sulphate of iron. r When the solution of the oxy-sulphate is mixed with iron filings, and kept in a covered vessel, part of the iron is dissolved by abstract- ing the second dose of oxigen from the oxide, and the whole is con- verted into sulphate. Tin produces the same effect. Sulphurated hydrogen gas brings on the change instantaneously, when made to pass through a solution of oxy-sulphate of iron.—Am. Ed 88 OCHRES. SPATHOSE IRON ORES. which requires only the addition of water to render it fit for use. The same powder, urged by a stronger heat, suffers its acid to escape; after which there remains only a martial earth, or metallic oxide, known by the name of Colcothar. I attribute the formation of all the yellow or red earths, commonly called ochres, to a similar decomposition of the pyrites. The heat produced by the decomposition of the pyrites has determined the respective colours of these earths; and they may be caused to pass artificially through these various shades, by treating them with va- rious degrees of fire. I have discovered, in the diocese of Uzes, banks of ochre of such uncommon fineness, and so very pure, that calcination converts it into a brown red, superior to every thing before known in trade. The manufactory which has been established under my care, has acquired all the celebrity which the superiority of its products could not but necessarily afford it. My experiments on these ochres, and the advantages wiiich they may afford to the arts, may be seen in the work which I have published on this subject, printed for Didot the elder, at Paris. I likewise found at Mas-Dieu, near Alais, a stratum of red ochre of so beautiful a colour, that it could scarcely be imitated. ARTICLE III. Concerning the Spathose Iron Ores, or Carbonates of Iron. The carbonic acid is sometimes combined with iron in ores; and the resemblance between this iron and spar, has procured it the name of the Spathose Iron Ore. The formation of this ore appears to be owing to the mutual decomposition of the carbonates of lime, and the sulphates of iron. A solution of copperas, in which calcareous spar was suffered to remain, produced this ore, according to the experiments of Mr. Sage. BOG ORES OF IRON. 89 Bergmann obtained from the ores Of this kind, which he analyzed, thirty-eight ounces of the oxide of iron, twenty-four ounces of the oxide of manganese, and fifty ounces of calcareous earth. It appears therefore that this ore contains two metals united by a calcareous ce- ment, which crystallizes always in its own form, as we find in the lapis calaminaris, the calcareous grit, &c. The spathose iron ores are wrought at Cascastel, in the diocese of Narbonne, at Bendorf on the banks of the Rhine, at Eisenartz in Styria, &c. ARTICLE IV. Concerning the Bog Ores of Iron, or Argillaceous Iron \ Ores. These ores consist merely of a martial oxide, in a state of greater or less purity, mixed with earthy sub- stances of the nature of clays. They appear to have been deposited by water; and are usually disposed in strata, which are frequently marked out, and as it were separated, into small prisms, whose formation arises simply from the shrinking of the clay. i. The eagle-stone, or aetites, ought to be ranked among the bog ores of iron. They are geodes of a round or oval form, having a hard external covering, while the cavity includes a detached nodule; and the noise produced by shaking one of these stones, arises from the nodule being at liberty to move within the stone. The name of eagle-stone has arisen from a notion, formerly entertained, that eagles placed it in their nests to facilitate the laying of their eggs; and wonderful powers of rendering labours safe and easy, were attributed to it in the times of superstition. 2. We are acquainted with an iron ore in round pieces, resembling bullets, of several lines in diameter, which ought to be considered as a variety of the preceding. An ore of this kind was begun to be wrought at Fontanez, Vol. II. M 90 NATIVE PRUSSIAN BLUE. near Sommieres ; and we find a considerable quantity oF these metallic globules among our red earths in the neigh- bourhood of Montpellier. 3. The purest oxide of iron, worn and carried along by waters, and afterwards, deposited, forms strata of various appearances and colours. These are called haematites. The colours arise from the various degrees of alteration in the oxide. They vary from yellow to the deepest red. The red haematites is used in the arts to buri;'sh geld or silver. It is cut into lorp: pieces, which when policed are known by the name of burnishers. This blecd-stoi.c h sometimes soft enough to be used instead of a crayon for drawing. Its figure is likewise subject to prodigious variation. It often appears as if composed of small prisms applied one against the other, in which case it is called the fibrous haematites. In other specimens it is tuberculated. It is very frequently found in compact irregular masses, such as those of the ores of the county of Foix. This must naturally exhibit the same variety of forms as the calcare- ous stalactites, because its mode of formation is nearly the same. ARTICLE V. Concerning native Prussian blue, or the Prussiate of Iron. Beccer speaks of a blue earth found at Turinge. Henc- kel informs us that a blue martial earth is found at Sehnee- burg and at Eibenstock. Cronstedt has described a native Prussian blue: Mr. Sage found it in the turf of Picardy. It is likewise found in Scotland, in Siberia, &c. and I possess a sulphure of iron in a state of decomposi- tion, which exhibits a true prussiate of iron upon one of its surfaces.* * Native Prussian blue is found in New Jersey and in Maryland.— Am. Ed. PLUMBAGO, OR BLACK LEAD. 91 ARTICLE VI- Conceming Plumbago, or the Carbure of Iron. The name of Plumbago is at present confined to that shining substance of a blackish blue colour, which is used to make the pencils called black-lead pencils. It has a greasy feel, exhibits a tuberciLa;ed fracture, soils the hands,' and leaves a black trace upn.i paper. Plumbago is found in many places; that of commerce is brought to us from Germany. We receive it likewise from Spain, from America, and irom England. It is also found in France. This mineral is almost always disposed in separate masses in the bowels of the eardi; and it is probably oh account of this form, that the ancients denoted it by the words Glebae Plumbarise. The plumbago of England differs from the other speci- mens in its texture, which is much finer, and of a greater degree of brilliancy. The English 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 most plentiful mine is in the county of Cumber- land. The plumbago of Spain is always accompanied with pyrites, which effloresce on the surface of the pieces ; ei- ther in small crystals, similar to those of the sulphate of 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 distance of four leagues from the Mediterranean sea. It is the worst kind which, comes. to market, and is used only to give a shining black co- lour to iron utensils. The American plumbago, which Mr. Woulfe procured for Mr. Pelletier, breaks easily, and exhibits small quart- zose grains in its internal part, as well as slight traces of a whitish clay. It is found in separate masses ; and its texture appears to consist of the union of an infinity of small scaly parts, wiiich at first sight might cause it to be taken for molybdena.* * Black lead is found in Bucks county, Pennsylvania, and about the grand Monadnock, in the township of Jaffrey, New-Hampshire,* and in Winterham, in the county of Amelia, in Virginia.—Am Ed * Belknap, vol. iil, p. t95. 9% TLUMBAGO, OR BLACK LEAD. France likewise possesses plumbago, and the chevalier Lamanon 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 thickness. It forms a stratum of four inches thick ; or rather the stratum consists of separate masses, which are sometimes several feet in length. It is accompanied by a vein of pyrites. The inhabitants of Bleoux sell this pro- duct at Marseilles at about fifteen livres per quintal. Mr. De la Peyrouse found plumbago with tourmalines in the county of Foix, and Mr. Darcet brought it from the Py- renean Mountains. Plumbago is indestructible by heat without the pre- sence of air. Mr. Pelletier exposed it to distillation, in the pneumato-chemical apparatus, by a violent fire during six hours, without the plumbago having lost weight, or suffered any other change. He exposed two hundred grains in a well-closed porcelain crucible to the fire of the manufactory at Seves, and it lost only ten grains. But when it is calcined with the concurrence of air, it then burns, and leaves but a small quantity of residue. Messrs. Quist, Gahn, and Hielm observed that one hundred grains, treated under a muffle in a shallow vessel, left only ten grains of oxide of iron. Mr. Fabroni dissipated the whole of a portion of plumbago exposed under the muf- fle. This calcination is a slow combustion, which is fa- cilitated by causing the matter to present a large surface, Und agitating it from time to time. If one part of plumbago, and two of very caustic dry alkali, be heated in a retort with the pneumato-chemical apparatus, the alkali becomes effervescent, hydrogenous gas is obtained, and the plumbago disappears. This beau- tiful experiment proves that the small quantity of water contained in the salt is decomposed ; and that its oxigene, by combining with the carbone of the plumbago, forms the carbonic acid. The experiment published by Scheele has been repeated and confirmed by Mr. Pelletier. The sulphuric acid does not act upon plumbago, ac- cording to Scheele. Mr. Pelletier has observed that one hundred grains of plumbago, and four ounces of oil of vitriol, being digested in the cold for several months, the acid acquired a green colour, and the property of con- PLUMBAGO, OR BLACK LEAD. 93 o-ealing by a very slight degree of cold. The sulphuric acid distilled from plumbago, passes to the state of the sulphureous acid ; at the same time that carbonic acid is obtained, and an oxide of iron is left in the retort. The nitric acid has no action upon plumbago unless it be impure. Eight ounces of nitric acid, distilled from half a gross of purified plumbago, neither altered its shin- ing appearance, nor deprived it of its unctuous feel. The muriatic acid dissolves the iron and the clay which contaminate native plumbago. Messrs. Berthollet and Scheele availed themselves of this method to purify it. The liquor being decanted after digestion upon the plum- bago, the residue is then washed, and submitted to dis- tillation to separate the sulphur. The muriatic acid alone has no action upon plumbago, but the oxigenated muri- atic acid dissolves it; the result being a true combustion effected by the oxigene of the acid, and the carbone of the p'umbago. If ten parts of the nitrate of potash be fused in a cru- cible, and one part of plumbago be thrown thereon by a little at a time, the salt will deflagrate, and the plumbago will be destroyed. The matter which remains in the cru- cible consists of very effervescent alkali, and a small por- tion of martial ochre. If plumbago be distilled with muriate of ammoniac, the muriate sublimes, coloured by a muriate of iron. All these facts prove that plumbago is a peculiar com- bustible substance, a true charcoal combined with a martial basis. Plumbago is more common than is imagined. The brilliant charcoal of certain vegetable substances, more especially when formed by distillation in close ves- sels, possesses, all the characters of plumbago. The char- coal of animal substances possesses characters still more peculiarly resembling it. Like it they are difficult to in- cinerate, they leave the same impression on the hands and upon paper; they likewise contain iron, and become con- verted into carbonic acid by combustion. When animal substances are distilled by a strong fire, a very fine pow- der sublimes, which attaches itself to the inner part of the neck of the retort. This substance may be made into excellent black lead-pencils, as I myself have proved. 94 PLUMBAGO, OR BLACK LEAD. Carbone may be formed in the earth by the decompo- sition of wood together with pyrites; but the origin of plumbago appeai-s lO me to be principally owing to the ligneous, and truly indecomposable, part of the wood, which resists the destructive action of water in its decom- position of vegetable substances. This ligneous sub- stance disengaged from the other principles, must form peculiar depositions and strata ; and Mr. Fabroni has as- sured me that the formation of plumbago in water is a common phenomenon, of which he had several times been a witness. This chemist, by his letter of the thir- tieth of January 1787, informs me that, in the dominions of the king of Naples, there are wells dug expressly for the purpose of collecting an acidulous water, at the bot- tom of which welis a quantity of plumbago is collected every six months. He supposes that the black mud which is found be- neath the pavement of Paris is plumbago formed in the humid way. There are likewise districts in Tuscany where plum- bago is formed in the humid way. This substance is of considerable use in the arts. It has been at all times applied to the purpose of making pencils, the most esteemed of which are those which come from England. They are made at Keswick in the coun- ty of Cumberland. The piece of plumbago is -,awed into very thin piates. The edge of one of ..hesc ou cs is fitted into a groove struck in a wooden cylinder ; and the thin plate of plumbago is then cut off ia'such a man- ner that the cavity of the small cyfinder remain > perfectly filled. The dust of plumbago is used to lubricate certain in- struments ; and it is likewise made into pencils of an in- ferior quality, by kneading it up with mucilage, or by fusing it with sulphur. The fraud may easily be disco- vered by the assistance of fire, which burns the sulphur; or by means of water, which dissolves the mucilage. Plumbago is likewise used to defend iron from rust. The hearths and plates of chimneys, and other similar utensils, which appear very bright, owe their colour to plumbago. Homberg has communicated a process, in the year X699, in which plumbago is applied to this use. ASSAY* OP IRON ORES. 95 Eight pounds of hogs-lard are melted with a small quan- tity of water, with the addition of four ounces of cam- phor. When this last is fused, the mixture is taken from the fire; and, while it is yet hot, a small quantity of plumbago is added, to give it a leaden colour. When this is to be applied, the utensils must be heated to such a degree, that the hand can scarcely be applied to them. In this state the composition must be rubbed on them, and afterwards wiped when the piece is dry. Those who prepare small shot, make use of black lead to polish and glaze it: the shot is rolled or agitated to- gether with a quantity of plumbago. Plumbago is like- wise used to make razor strops. When kneaded up with clay, it forms excellent crucibles, which we receive from Passaw in Saxony. One part of plumbago, three of ar- gillaceous earth, and a small quantity of cows dung very finely chopped, form an excellent lute for retorts. Mr. Pelletier has used it with great advantage. This lute is exceedingly refractory; and the glass will melt without the covering changing its form. To make the assay of an iron ore, I find the following flux very advantageous :—I mix four hundred grains of calcined borax? forty grains of slacked lime, two hundred grains of nitrate of potash, and two hundred of the ore to be assayed. I pulverize this mixture, and place it in a lined crucible, which I cover. The heat of a forge fur- nace is sufficient to effect the reduction. In the space of half an hour, the button of metal is found deposited at the bottom of the vitrified flux. The process for working iron mines varies according to the nature of the ore. The metal is sometimes so little altered, and so abundant, that nothing more is necessary than to mix it with the coal, and fuse it. This simple and ceconomical process forms the basis of the Catalan method, which may be employed in treating the spathose iron ores, those of Elbe, the haematites, and other rich and pure ores. But it cannot be applied to such as con- tain much foreign matter capable of becoming converted into slag. For this reason, the experiments made in the county of Foix on the ores of various countries, and vari- rious qualities, have not succeeded. On this head, the 96 CRUDE OR CAST IRON. work of Mr. De la Pcyrouse, and the memoirs of the Baron de Dietrich, may be consulted. The furnaces in wiiich iron is fused, are from twelve to eighteen 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 stone, named (by the French) castine, if the ore be argillace- ous ; but if the gangue be calcareous, the workmen em- ploy argillaceous earth, which is named herbue. The furnace is charged at the upper part; and the fire is excited by bellows, or hydraulic machines. The ore melts as it passes through the coal, and is collected at the bottom, where it is maintained in a liquid state. At the end of every eight hours it is suffered to flow out into the mould or hollow channel made in the sand. Crude iron, cast in suitable moulds, forms cliimncy- backs, pots, cauldrons, pipes, and an infinity of utensils or vases, which could not be obtained without difficulty by forging the iron. The works which are established at Creusot in Burgundy surpass every thing which can be desired in this species of industry. This first product is called Cast or Crude-Iron. It is brittle; but may be rendered ductile by heating it again, and hammering it. For this purpose the pig is fused again, and stirred while in the state of fusion : after which it is carried to the forge hammer. By this treatment the iron becomes ductile, assumes a fibrous texture, and is formed into square or flat bars for the purposes of trade. Iron is likewise capable of a degree of superiority, which is given to it by placing it in contact with coaly substances, and softening it to such a degree that these may penetrate into its texture. It is then known by the name of Steel. We are indebted to Mr. Jars for very interesting accounts of the steel manufactories in England. The manufactory established at Amboise is not inferior to those of England, as was ascertained by comparative ex- periments made upon the products of the several manu- factories, at Luxemburg, on Friday the 7th of Septem- ber, 1786. We may therefore divide the different states of iron into cast or crude iron, iron properly so called, and VARIOUS STATES OF IRON. 97 steel. It is clear that these three states are nothing more than modifications of each other; but the cir- cumstances on which they depend, and the principle which establishes their difference, were till lately un- known. The celebrated Bergmann has given an analysis of the various states of iron, and has drawn up the following table: Cast Iron. Steel. Iron. Inflammable Air - 40 48 ■50 Plumbago - " 2-20 0- 50 0- 12 Manganese 15 -25 15 - 25 15 - 25 Siliceous Earth 2 - 25 0- 60 0-175 Iron 80 - 30 83 - 65 84 - 45 This celebrated chemist has confirmed by his results the conclusion of Reaumur, who always considered steel as an intermediate state between crude and malleable iron. We are indebted to three French chemists, Messrs. Monge, Vandermonde, and Berthollet, for a quantity of much more accurate information respecting all these states. , We may consider iron ores as natural mixtures of iron, oxigene, and various foreign substances. When an ore is wrought, the object of the operator is to clear the iron of all these matters. To effect this separation, the ore is thrown into the smelting furnaces, with different propor- tions of charcoal. These matters are heated together until they arrive at the hottest part where the mixture falls; and, after suffering the strong action of the fire, is preci- pitated in fusion, and forms a fluid mass at the bottom of the furnace. The earths and stones, nearly in a vitrified state, float above the fluid; and the oxigene, being partly driven out, remains likewise in a greater or less quantity in the crude iron. The crude iron is either white or grey, or black. In our inquiries concerning the cause of these three kinds of iron, and their qualities, we can refer them only to the proportions of foreign principles con- Vol. II. N 98 VARIOUS STATES OF IRON. tained in the crude iron. These principles are carbone and oxigene. 1. Crude iron contains carbone. The ladles which are used to agitate, take up, and pour out diis melted metal, become covered with a coating of plumbago, wiiich contains nine-tenths of carbone: and cast iron, strongly heated in contact with the coal, suffers a part to escape'or exude from its surface when it is slowly cooled. Crude iron emits sparks when it is heated; the acids which dissolve it always leave a residue wiiich is purely carbonaceous. The hydrogenous gas, which is obtained by treating these irons with acids, always affords the car- bonic acid by combustion. 2. Crude iron contains oxigene. Several mineralogists attribute the fragility and brilliancy of crude iron to its still containing iron in the state of oxide. This opinion, which is generally adopted, supposes the existence of oxigene. Crude iron, urged by a violent heat in close vessels, affords the carbonic acid, and passes to the state of soft iron ; because its oxigene then unites to the carbo- naceous principle, and constitutes the carbonic acid, which exhales, and clears the crude iron from the two principles which altered its quality. Oxigene and carbone exist therefore in crude iron, but they may exist in three different states—1. A large quan- tity of carbone, and a small quantity of oxigene. 2. An exact proportion between these two principles. 3. Much oxigene, and a small quantity of carbone.—Now wre find these three states in the three kinds of crude iron which we have distinguished, as is proved by analysis; and, as we may judge by the secondary processes, to correct these imperfections, or to convert crude iron to the mal- leable state. 1. In the first case, that iron which contains an excess of carbone is agitated or stirred as it flows out. It is kept a long time exposed to the action of the bellows, and the smallest possible quantity of charcoal is made use of. We see that in this process the properest methods are used to facilitate the combustion of this excess of the carbona- *ceous principle. 2. In the second case, that kind of iron in which the principles exit in accurate proportions, requires only the VARIOUS STATES OF IRON. 99 s uction of heat to unite and volatilize the two foreign principles. The crude iron is put into a state of ebulli- tion by the disengagement of the acid which is formed, and exhales. 3. In the third kind, or that wiiich contains oxigene in excess, the bellows are urged less violendy ; and the metal is penetrated with coal in order to combine wiih the oxigene. Here therefore we see theory and practice go together. The former explains the usual manipulations, and affords us principles in cases wherein experiment too frequently fails. Steel is a kind of iron which contains carbone only; and its existence 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 fusion of the ore. 2. Or, afterwards, by the cementation of iron with coaly substances. 1. In some parts of Hungary, and in the county of Foix, iron ores are wrought which contain the metal near- ly in the disengaged state; and the cast iron, when duly hammered, affords iron and steel in a greater or less quan- tity, according to the management of the fire, the quanti- ty of air afforded by the tuyere, the quantity of coal made use of, and the nature of the ore. In this opera- tion, the iron being scarcely at all calcined in the ore, becomes charged with coaly matter only, and the result is steel. 2. If the coaly principle be combined with iron in a ductile state, and deprived of all foreign matter, the com- bination being effected by cementation or otherwise, die iron will pass to the state of steel; and the qualities of this steel will vary according to the proportions of car- bone. The purity of the iron, and the care which is ta- ken to avoid the oxidation of the metal, establish the va- rious kinds of steel which are met with in commerce.* ^ * Cast steel may be made in the following manner : Take small pieces of iron, and place them in a crucible, with a mixture of the carbonate of lime and the earth of Hessian crucibles. The mat- ters are to be exposed to the heat of a powerful air furnace. After the melting of the iron, it must be completely covered by the pow- 100 VARIOUS STATES OF IRON. The nature and the principles of steel being once ad- mitted and established, the following facts will explain themselves. 1. Since steel contains no foreign principle but car- bone, it is not surprising that it remains unchanged by a violent heat in close vessels. 2. Steel, repeatedly heated, and exposed while hot to a current of air, loses its properties, and passes again to the state of soft iron. 3. Steel kept plunged for a time in crude iron in which oxigene predominates, becomes itself converted into soft iron. 4. Soft iron kept for a time plunged in crude iron, wherein carbone predominates, becomes converted into steel. 5. Iron, by passing to the state of steel, increases in weight one hundred and seventieth part. Ductile iron would be a very soft metal, if it were cleared of all foreign substances.* From all these facts we may conclude—1. That crude iron is a mixture of iron, carbone and oxigene. 2. That the products of crude iron are white, grey or black, ac- cording to the proportions of oxigene and carbone which it contains. 3. That the steel of cementation is merely a mixture of iron and Carbone. 4. That steel which is over cemented, is an iron containing too large a quantity of carbone. 5. That iron would be a very soft metal, if it were not mixed with a greater or less quantity of oxi- gene and carbone. Forged iron is distinguished into soft iron, and eager or brittle iron, by us (the French) called Rouvrain. This last has a coarser grain than the other : it is divided into red short iron, and cold short iron. The cause of this phenomenon is known : it arises from a phosphate of iron, which was discovered by Bergmann. This celebrated chemist constantiy observed a precipitate to be formed in dered lime and crucibles, to prevent its being acted upon by the ox- igenous portion of atmospheric air. If the fire be well kept up, an hour will be sufficient to convert two pounds of iron into hard steel of an excellent quality, capable of beine;- forged.—Am. Ed. * The editor of this work has made iron tacks nearly as soft as lead, by transmitting hydrogen gas" over them for several hours, confined in an earthen tube, and exposed to a red heat.—4m. Ed. VARIOUS STATES OF IRON. 101 the solutions of cold short iron in the sulphuric acid. It was a white powder, which he called Siderite, and at first supposed to be a peculiar metal; but Mr. Meyer of Ste- tin has proved that it is a true phosphate of iron. Soft iron does not afford it. All the irons of Cham- pagne afford about a dram, or gros, in the pound of iron. In order to obtain siderite, it is'necessary that the solu- tion should be saturated by a gende heat on the sand bath. If the solution be made too quickly, the siderite is then mixed with ochre, which alters its purity and whiteness. A precipitate is formed, which takes place so much the more speedily, as the solution is more diluted with water each time after filtration. The precipitate is formed in the first three or four days; a second is obtained towards the sixth day; and that which afterwards falls down is mixed with ochre. Siderite may likewise be obtained by dissolving iron in the nitric acid, and evaporation to dryness. The iron is oxided by this first operation. More nitric acid being poured on this residue, dissolves only the siderite, with- out touching the oxide of iron. A second evaporation must then be made ; and the residue must be diluted with water, to evaporate the last portions of nitric acid: and that which remains is siderite. It is soluble in the sul- phuric, nitric, and muriatic acids, from which it may be precipitated by pouring into the solution as much alkali as is necessary to saturate the acid solvent. If the alkali be added in excess, ochre is then precipitated; and the result is a phosphate, and a salt arising from the union of the acid made use of and the alkali which has served for the precipitation. The fixed and volatile alkalis, and lime water, decom- pose siderite. It is likewise decomposed by projecting it upon fused nitre. When it has been precipitated by ammoniac, crystals may be obtained by evaporation, which when treated with powder of charcoal afford phosphorus. The ochreous precipitate affords iron by reduction; it is therefore a com- bination of the phosphoric acid and iron. Every solution of iron is precipitated in the form of siderite by the phos- phoric acid. 102 HABITUDES OF IRON. The effect of the tempering of iron likewise deserves the attention of the chemist. I am of opinion that the hardness and brilliancy which iron acquires by this opera- tion, arises from its integrant parts, which are separated by the heat, being kept and left at a certain distance from each other by the" sudden cold, which drives out the heat, without bringing the constituent principles of the mass together. The iron is then more britde, because the af- finity of aggregation is less. Iron is easily oxided. A bar of iron which is heated a long time in the forge furnace, becomes oxided at its surface ; and the coatings of metal which pass to the state of oxide, are separated from the mass in the form of scales. The most degraded and the most altered metal, in the state when it is no longer attracted by the magnet, forms an oxide of a reddish brown colour, known by the name of Astringent Saffron of Mars, or the Brown Ox- ide of Iron. The colour of this oxide varies according to its degree of oxidation. It is yellow, poppy-colour, or red; and is easily reduced into a black powder, when heated with coaly matters. The combined action of air and water constitutes a martial oxide, known by the name of Aperitive Siiffron of Mars. This composition is produced by the combi- nation of oxigenous gas and carbonic gas with the iron. The exposition of the iron to a humid atmosphere rusts it speedily, and causes it to pass to the state of aperitive saffron of Mars. This preparation is a true carbonate of iron. Water likewise acts 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 deposited, which is called the Martial iEthiops of Lemery, or the Black Ox- ide of Iron. It is a commencement of calcination effect- ed by the air contained in the water; but more especially by the decomposition of the water itself. The fixed and volatile alkalis, in the fluid state, being digested upon iron, oxide a slight portion, which falls down in the form of asthiops. AH acids act more or less upon iron. HABITUDUS OF IRON. 103 1. The concentrated sulphuric acid is decomposed by boiling upon this metal. If the mixture be distilled to dryness, the retort is found to contain sublimed sulphur, and a white mass, partly soluble in water, but incapable of crystallization. But if the diluted sulphuric acid be poured upon iron, a considerable effervescence arises in consequence of the disengagement of hydrogenous gas. In this operation, the water is decomposed, its oxigene is employed to cal- cine the metal, while the hydrogene is disengaged; and the acid acts upon and dissolves the metal without being decomposed. This solution, when concentrated by eva- poration, affords the sulphate of iron, which we have al- ready treated of. 2. The nitric acid is decomposed rapidly upon iron. The solution is of a red brown colour, and suffers the ox- ide of iron to fall down at the expiration of a certain time. If new iron be plunged in this solution, the acid dissolves it, and lets fall the oxide which it held in solution. If the solutions be concentrated, martial ochre of a red brown colour falls down. If the concentration be carried still further, a reddish jelly is formed, which is partially soluble in water. Iron precipitated from its solution by the carbonate of potash, is easily dissolved by the superabundant alkali, and forms the martial alkaline tincture of Stahl. Mr. Maret has proposed to precipitate the iron by the caustic alkali, to make the sethiops immediately. Mr. Darcet, in rendering an account of the process of Mr. Maret to the Royal Society of medicine, has proposed that of Mr. Crohare, which consists in boiling upon the iron wrater acidulated with the muriatic acid. Mr. De Fourcroy made a course of experiments upon the martial precipitates, which throws much light upon the causes of the astonishing varieties observed in them. He has proved that the whole depends either on the na- ture of the acid, or the manner of operating at the time of making these precipitates, or the quality of the preci- pitant. 3. The diluted muriatic acid attacks iron with vehe- mence. Hydrogenous gas is disengaged, which arises from the decomposition of the water. If the solution be 104 HABITUDES OF IRON. concentrated and left to cool when it is of the thickness of syrup, a magma is formed; thin flattened crystals are per- ceived, which are very deliquescent. The muriate of iron, distilled in a retort by the Duke d'Ayen, exhibited verv singular phenomena.* The first product was an acid phlegm. At a stronger heat, a non-deliquescent mu- riate of iron sublimed, at the same time that very trans- parent crystals rose to the roof of the retort, in the form of the blades of razors, which decomposed the light in the same manner as the best prisms. At the bottom of the retort there remained a styptic deliquescent salt, of a brilliant colour, and a foliated appearance, which exactly resembled the large plated talk, improperly called Musco- vy Glass. This last salt exposed to a violent heat, afford- ed a sublimate more astonishing than the former products. It was an opaque substance, truly metallic, wrhich exhibited sextons of hexahedral prisms, polished like steel. It was iron reduced, and sublimed. 4. It was long since known that iron is precipitated from its solutions by vegetable astringent substances :f * The muriate of iron has been recommended in cases of reten- tion of urine, and has been used with success. Ten drops of this preparation given every ten minutes is a dose for an adult.— Am. Ed. t All vegetable astringent subtances do not precipitate iron of a black colour from its solution in acids. Those only which contain the Gallic acid, have this effect The astringent principle is com- posed of the gallic, malic, or some other vegetable acid, united to a substance which the Editor has taken for the earth of alum, and which may be thrown down from infusions of astringent plants, by a solution of potash. The property which some vegetables possess, of striking a black colour, with a solution of green vitriol, has long been regarded, as an indubitable test of astringency, but this doctrine is false, for the fol- lowing reasons. First Many vegetables contain the gallic acid, which are not astringent to the taste. Secondly. The astringency of a vegetable may be destroyed by triturating it with magnesia or the alkalis, and the mixture will possess the property of producing a black colour, with solutions of iron. Thirdly. If a small portion of the oil of vitriol be added to an astringent vegetable, it appears to increase the astringency of it to the taste, and yet the mixture will not precipitate solutions of iron black. Fourthly. Many vegetables are astringent to the taste which have no effect on solutions of iron.—Am. Ed. FORMATION OF INK. 105 and the black dyes, and the fabrication of ink, are found- ed on this known fact. But it was not till lately that an acid has been proved to exist in these substances, which combined with the iron, and which may be obtained from all these astringent vegetables*, either by simple d s illa- tion, or by mere digestion in cold water. The most sim- ple process is the following: Infuse one pound of powder of nut-galls in 2| pints of pure water. Leave the mixture together for four days, frequently shaking the infusion. Then filter, and leave the fluid in a vessel simply covered with blotting paper. The liquid becomes covered with a thick pellicle of mouldiness, and a precipitate falls down in proportion as the infusion evaporates. These precipitates collected, and dissolved in boiling water, form a liquor of a brown yellow colour, which, evaporated by a gentle heat, de- posites—1. A precipitate which resembles fine sand. 2. crystals disposed in the form of a star. This salt is grey; and it is impossible to. obtain it of a whiter colour by any repetition of solutions and crystalliza- tions, f It is an acid which effervesces with chalk, and reddens the infusion of turnsol. Half an ounce of this salt is soluble in an ounce and a half of boiling water, or twelve ounces of cold water. Boiling spirit of wine dissolves its own weight of this acid; but cold spirit dissolves only one-fourth. * This is a mistake of the author.—Am, Ed. t The following is one of the best methods of obtaining the acid of galls. One ounce of the best Aleppo galls is to be boiled in sixteen ounces of water, until it is reduced to eight ounces. The extractive matter is to be separated from the acid, by mixing with the liquor, as much of pure aluminous earth, as would make two ounces of sul- phate of alumine, and the liquor is to be filtered. The extractive matter, tannin, and all the heterogeneous bodies will remain on the filter, combined with the aluminous earth, while the gallic acid is dissolved in the liquor that passes through. The Editor obtains the gallic acid by distilling to dryness in a glass retort, the expressed juice of the unripe fruit of the Dyospyros Virgimana, American Prune, Date plum, or Persimon tree. Water rises at first which must be thrown away, afterwards the gallic acid passes over into the receiver.—Am. Ed * Vol. II. O 106 ACID OF GALLS. This salt is inflammable in the fire. It melts, and leaves a coal of difficult incineration. When this acid is distilled in a retort, it becomes at first fluid, gives out an acid phlegm, but no oil; and, towards the end, a white sublimate rises, which attaches itself to the neck of the retort, and remains fluid as long as it is hot, but afterwards crystallizes. Much coal is found in the retort. The sublimate has nearly the taste and smell of acid of benzoin, is as soluble in water as in spirit of wine, reddens the infusion of turnsol, and pre- cipitates metallic solutions with their different colours, and iron black. The solution of the salt of the nut-gall, poured into a solution of gold, renders it of a dark green; and precipi- tates a brown powder, which is gold revived. The solution of silver becomes brown; and at length deposites a grey powder, which is revived silver. The solution of mercury is precipitated of a yellow orange colour. The solution of copper affords a brown precipitate. The solution of iron becomes black. The solution of the acetite of lead is precipitated white. This salt is changed into the oxalic acid, if the nitric acid be distilled from it. The basis of ink consists of a solution of iron by the gallic acid. To make good ink, take one pound of nut- galls, six ounces of gum arabic, and six ounces of green copperas, with four pints of common water. The nut-galls must be bruised, and infused for four hours with- out boiling. The pounded gum must be first added, and suffered to disssolve; and, lastly, the copperas, which im- mediately converts the fluid to' a black colour. Lewis, of the Royal Society of the London, made many re- searches on this subject; but he always returns to the forementioned substances. Powdered sugar is sometimes added, to render the ink shining. 5. The vegetable acid likewise dissolves iron with facility. It is this which holds the metal suspended in vegetables; and it may be precipitated from wine in the form of jethiops, by the means of alkalis. DISCOVERY OF PRUSSIAN BLUE. 107 Cream of tartar, or the acidulous tartrite of potash, likewise dissolves iron; and the various degrees of concentration of this solution forms the soluble martial tartar, the aperitive extract of Mars, and the balls of Nancy. 7. The solution of iron, by the oxalic acid, affords prismatic crystals of a greenish yellow colour, and a somewhat astringent taste, soluble in water, and efflores- cing by heat. 8. Iron dissolved by the prussie acid, forms Prussian blue, or the prussiate of iron. A singular mistake gave rise to the discovery of this substance. Diesbach a chemist of Berlin, being desi- rous of precipitating a decoction of cochineal with fixed alkali, borrowed of Dippel an alkali upon which he had several times distilled animal oil; and as the decoction of the cochineal contained sulphate of iron, the liquor im- mediately afforded a beautiful blue. The experiment being repeated was followed with similar results; and this colour became an object of commerce, under the name of Prussian Blue. Prussian Blue was announced in the Memoirs of the Academy of Berlin in the year 1710, but without any account of the process, which was kept a secret until other chemists discovered it. The process was rendered public in the year 1724, in the Philosophi- cal Transactions, by Woodward; who declared that he had received it from one of his friends in Ger- many. To make Prussian blue, four ounces of alkali are mixed with the same weight of dried bullock's blood,, and the mixture exposed in a crucible, which is covered in order to stifle 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 Phlogisticated Alkali. On the other hand, two ounces of the sulphate of iron and four ounces of the sulphate of alumine are dissolved in a pint of water. The two so- lutions are mixed, and a blueish deposition falls down, which is rendered still more intensely blue by washing it with muriatic acid. 108 THEORY OF PRUSSIAN BLUE. Such is the process used in chemical laboratories; but in the works in the large way another method is follow- ed. Equal ports of the raspings of horns, clippings, of skins, or other animal substances, are taken and con- verted into charcoal. Ten pounds of this coal are mixed with thirty pounds of potash, and the mixture is cal- cined in an iron vessel. After twelve hours ignition, the mixture acquires the form of a soft paste, which is poured out into vessels of water. The water is then filtered; and the solution mixed with another, consisting of three parts of alum, and one of sulphate of iron. I have likewise made Prussian, blue by calcining and burning in the same vessel equal parts of the shavings of horns and tartar. I received the animal oil and the ammoniac, afforded by the calcination of these substances in large casks, which communicated with each other, and formed an apparatus after the manner of Woulfe. It has likewise been observed that the tips of the thyme, the sun-flower, and several other vegetable sub- stances, when treated with alkali, communicate to it in a certain degree, the property of precipitating iron of a blue colour. Much reasoning has been exhibited on the etiology of this phenomenon. Messrs. Browm and Geoffroy con- sidered Prussian blue as the phlogiston of iron, developed in the lixivium of blood. The abbe Menon imagined that the colour of iron was blue, and that the phlogisti- cated alkali precipitated it in its natural colour. Mr. Macquer refuted the opinion of his predecessors in the year 1752; and proposed a system, in which he considers Prussian blue as iron supersaturated with phlogiston. This skilful chemist proved that the blue is not soluble in any respect in acids; and that the alkalis are capable of dissolving the colouring matter of the Prussian blue, and of becoming saturated with it to such a degree as to be no longer capable of effer- vescing. Mr. Sage affirmed that the iron was saturated with the phosphoric acid; and the celebrated Bergmann likewise suspected the existence of some animal acid as is proved ANALYSIS OF PRUSSIAN BLUE. 109 by his notes on the lessons of chemistry of Scheffer. But it was reserved to the celebrated Scheele to convert these suspicions into certainty. He has proved that the lixivium of blood, exposed for a certain time to the air, loses the property of precipitat- ing iron of a blue colour; and he has shewn that this cir- cumstance depends on the carbonic acid of the atmos- phere, which disengages the colouring part. By adding a small quantity of sulphate of iron to this lixivium, it is no longer changed in consequence of its remaining in the carbonic acid By boiling this lixivium upon an oxide of iron, it is likewise no longer capable of change in the carbonic acid. The iron has therefore the property of fixing and retaining the colouring principle ; but it is ne- cessary that it should not be in the state of oxide. Prussian blue, treated in the way of distillation with the sulphuric acid, permits a fluid to escape that holds the prussic acid in solution, which may be precipitated upon iron. The processes of Scheele, to obtain this acid in a state of purity, consist in putting two ounces of pulverized Prussian blue into a glass cucurbit, with one ounce of red precipitate, and six ounces of water. This mixture is to be boiled for some minutes, continually stirring it. It then assumes a yellow colour inclining to green. The fluid being filtered, two ounces of boiling water are to be thrown on the residue. This liquor is a prussiate of mer- cury, which cannot be decomposed either by alkalis or acids. The solution is then poured into a bottle, in which an ounce of newly-made filings of iron is put: three gross of concentrated sulphuric acid are to be added, and' the whole agitated strongly for several minutes. The mix- ture becomes perfectly black by the reduction of the me* cury; the liquor loses its mercurial taste, and exhibits that of the colouring lixivium. After suffering it to stand at rest for a time, it is decanted, put into a retort, and dis- tilled by a gende fire. The colouring principle passes first, because more volatile than water. The operation must be put an end to, as soon as one quarter of the liquor has passed over. As this product contains a small quantity of sulphuric acid, it may be cleared of it by re-distilling it from pulverized chalk by a very gentle fire. The prus- 110 ANALYSIS OF PRUSSIAN ACID. sic acid then comes over in a state of the greatest purity. Scheele recommends that the vessels be well luted, be- cause the acid would otherwise escape on account of its great levity. It is even of advantage to put a small quan- tity of water into the receivers, to absorb the acid; and it would likewise be very proper to surround them with pounded ice.* This acid has a particular smell, which is not disagree- able ; and its taste is sweet. It does not redden blue paper; but renders the solu- tions of soap and of the sulphure of alkali turbid. Mr. Westrumb pretends that the prussic acid is the same as the phosphoric; for he obtained siderite from Prussian blue, and formed animal earth by mixing the lixivium of blood with a solution of calcareous earth. The solution of iron in the prussic acid affords Prussian blue. We are indebted to Mr. Berthollet for a very in-, teresting series of experiments upon the prussic acid, and its combinations. The oxide of iron is capable of existing in two differ- ent states in combination with the prussic acid. If the oxide predominates, the combination is yellowish; but if its proportion be less, the product is Prussian blue. All the acids are capable of dissolving the portion or surplus of oxide which constitutes the difference between the first and second combination. The prussiate of potash contains oxide of iron. If an acid be poured in, this oxide is dissolved, and is precipi- tated by double affinity in the form of Prussian blue. The * Prussic acid may be obtained in a state of purity, by pouring upon one part of Prussian blue, half as much sulphuric acid diluted with an equal quantity of water, and subsequent distillation. The prussic acid passes over in alcohol, placed in a receiver. Mr. Schroeder, apothecary at Berlin, asserts that the prussic acid is contained in the aqua lauro cerasi, and the distilled water from the flowers of the peach tree, as likewise in the infusion of bitter al- monds. He was led to this discovery by observing, that the prussic acid has the quality common with those distilled waters and infusions of killing animals ; and that the prussic acid, as well as the above-men- tioned water, possesses the smell of bitter almonds. The author thinks it probable, that what has been hitherto called the narcotic principle, may be nothing but the prussic acid.—Am. Ed. ANALYSIS OF PRUSSIAN ACID. Ill prussiate of potash made by a gentle heat, afterwards eva- porated to dryness, then re-dissolved, and filtered, no longer affords the blue upon the addition of acids. It crystallizes in square plates with their edges cut slantways, forming octahedrons, whose two opposite pyramids are truncated. This solution of the prussiate of potash, when mixed with the sulphuric acid, deposites Prussian blue, if it be exposed to the solar light, or to a strong heat. In these processes the prussiate of alkali may be entirely de- composed ; the prussiate of iron, when precipitated by the action of the alkaline prussiate, carries down with it a no- table proportion of alkali, of which it may be cleared by washings, which contain the alkaline prussiate. It is the same with regard to precipitations by the prussiates of lime and ammoniac. The prussiate of mercury crystallizes in tetrahedral prisms, terminating in quadrangular pyramids, whose planes answer to the angles of the prisms. Iron in its metallic state decomposes the prussiate of mercury, and deprives it both of its oxigene and its acid. The oxide of mercury likewise decomposes the prussiate'of iron and seizes its acid. The prussiate of mercury is but imper- fectly decomposed by the sulphuric and muriatic acids. These acids form trisules, or triple salts, with it. The precipitate of the nitrate of barytes by the prussic acid, is not the compound which Bergmann supposed it to be, but is merely a trisule. The prussic acid readily precipitates alumine from its nitric solution; the alumine nevertheless yields its prussic acid to iron. The oxigenated muriatic acid, when mixed with the prussic acid, is again converted to the state of common muriatic acid: the prussic acid assumes a more lively smell, becomes more volatile, is deprived of its affinity to alkalis and lime; it precipitates iron of a green colour, and the green becomes blue if the precipitates be exposed to light, or if it be treated with the sulphureous acid. The prussic acid, impregnated with the oxigenated mu- riatic acid, and exposed to light, assumes the smell of an aromatic oil, is collected at the bottom of the water in the form of an oil which is not inflammable, and rises in va- pour by a gentle heat. By repeating this process it may 112 ANALYSIS OF PRUSSIAN ACID. be totally decomposed; and dien this species of oil be- comes concrete, and is reduced into crystals. The acid appears to have undergone a partial combus- tion in this operation; at least the light and the sulphure- ous acid do not restore it but by depriving it of oxigene. The oxigenated prussic acid, mixed with lime or a fixed alkali, becomes totally decomposed. Volatile alkali is disengaged; and if the alkali was very caustic such as die alcohol of potash, it becomes effervescent. The prussic acid of Scheele is only decomposed in part by this process; whence Mr. Berthollet concludes that it is composed of hydrogene, nitrogene, and carbone. These experiments do not prove that oxigene exists in this acid. The water affords that which enters into the carbonic acid, produced by the distillation of the prussic acid. Prussian blue takes fire more easily than sulphur, and detonates strongly with the oxigenated muriate of pot- ash. The prussiate of mercury detonates still more strongly with the nitrate of mercury. The gas of these detonations has not yet been collected. The prussic acid, combined with alkali and the oxide of iron, cannot be se- parated by any acid without intervention of heat or light; and when it is disengaged, it is no longer capable of se- parating iron from the weakest acid, unless it be in the way of double affinity. Mr. Berthollet thinks that the elastic state of this acid diminishes this affinity; and that it is necessary, in order that it may easily enter into com- bination, that it should have lost some of its specific heat. It is this which renders the oxigenated acid so feeble. Prussian blue afforded me, by distillation, in the ounce, one gross twenty-four grains of ammoniac, thirty-six grains of the carbonate of ammoniac, four gross twelve grains of oxide of iron, or alumine, and one hundred and sixty-four inches of hydrogenous gas burning with a blue flame. The ammoniac comes over in combination with a small quantity of the colouring principle, which it takes up, and holds in solution : the sulphuric acid renders this visible. Ammoniac heated upon Prussian blue decomposes it, by seizing the colouring matter. Lime-water digested upon Prussian blue dissolves the colouring principle by the assistance of a gentle heat; the HABITUDES OF IRON. 113 combination is rapid, and the water acquires a yellow co- lour. By filtration, the liquor passes of a fine bright yel- low, no longer converts syrup of violets to a green, and is no longer precipitated by the carbonic acid. It appears ^ to be completely neutralized, and affords an exceedingly fine blue, when poured into a solution of the sulphate of iron. The prussiate of lime has been proposed, by Messrs. Fourcroy and Scheele, as the most accurate means of ascertaining the presence of iron in any mineral water. The pure fixed alkalis immediately discolour Prussian blue in the cold. This combination produces heat; and the pure alkalis ought to be preferred to the carbonates of alkali in experiments of this nature. Magnesia likewise seizes the colouring matter of Prus- sian blue ; but much more weakly than lime-water. A mixture of equal parts of steel filings and nitrate of potash, thrown into a crucible strongly ignited, detonates at the end of a certain time, with the disengagement of a considerable quantity of very bright sparks. The re- sidue, when washed and filtered, affords an oxide of iron. of a yellowish colour, known by the name of Zwelfer's Saffron of Mars. Iron decomposes the muriate of ammoniac very well. Two gross of steel filings, and one gross of this salt, afford- ed Mr. Bucquet, by distillation in the pneumato-chemi- cal apparatus over mercury, fifty-four cubic inches of an aeriform fluid; half of wiiich was alkaline gas, and the other half hydrogenous gas. This decomposition is founded on the strong action of the muriatic acid on iron. One pound of the muriate of ammoniac in powder, and one ounce of steel filings, sublimed together, form the martial flowers, or Ens Martis. . These flowers con- sist merely of the muriate of ammoniac, coloured, and rendered yellow by an oxide of iron.* The oxide of iron decomposes the muriate of ammoniac much better. This is an effect of double * Thev consist of muriate of ammoniac and muriate of iron. —Am. Ed. Vol. IT. P 114 TIN PLATES. affinity. < The ammoniac which rises is sometimes effer- vescent. A mixture of good filings of steel and sulphur, moist- ened with a small quantity of water, becomes hcakd in the course of several hours. The water is decern posed, the iron rusts, the sulphur is converted into ^cid, the hydrcg nous gas of the water exhales, and the heat is sometimes sufficient to set the mixture on fire. This phenomenon constitutes the volcano of Lemery. There is the stor.gest analogy both in the phenomena ■and effects of the inflammation of this volcano, and the decomposition of pyrites. Sulphur combines easily with iron by fusion, and then forms a true martial pyrites.* Iron may be alloyed with several metallic substan- ces ; but the only alloy which is used in the arts is that which it contracts with tin, to form white iron, or tin plates. To form the tin plates (commonly known by the name of Tin in England), the softest iron is chosen, which is reduced into very thin plates. Care is taken to polish or clean the surface very well; and this is done in several ways. The pieces are rubbed with sand-stone, and after- wards 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 ammoniac is likewise used in some manufactories. For this purpose the plates are disposed in a chamber, in which a certain quantity of sal ammoniac is volatilized. The salt forms a covering over the whole surface of every plate, and possesses the double advantage of clearing it from rust, and affording the coal} principle necessary to prevent the calcination of the metal. When the iron is well cleared, the plates are plung- ed vertically into a bath of tin, whose surface is covered with pitch, or tallow. They are turned in the bath; and * An easy method of combining iron and sulphur, is to give a bar of iron a white heat, rub it with a roli of brimstone, and receive the product in a bucket of water.—Am. Ed. USES OF IRON. 115 when taken out they are wiped with saw-dust, or bran. The uses of iron are so very extensive, that there are few aits which can be practised without it. It is with jus- tice considered as die soul of all the arts. Some of its ores are used in their native state; such as the haematites, which is made into burnishers. The sulphate of iron is the basis of all black colours, ink-., &c. The ochres are used by painters, under the name of Umber ; and the brown red has the most extended use. With us (in France) it is applied to give a colour to brick pavements, to paint our doors and windows, to smear our casks, and to secure them from decay, and insects in sea voyages. Cast iron is used to make boilers, chimney-grates, hearths, pots, &x. The instruments of agriculture are made of this metal: steel is used not only as steel; but its hardness renders it proper to cut and work the other metals. The magnetical property of iron has led to the dis- covery of the mariner's compass; and this metal, if it were productive of no other advantage to mankind, would on that account be entitled to dieir greatest atten- tion. Prussian blue is an agreeable colour, greatly esteemed, and much used. Iron likewise furnishes the art of medicine with reme- dies. It is the only metal which is not noxious, and it has such an analogy with our organs, that it appears to con- stitute one of the elements of the human frame. Its effects in general consist in strengthening the stomach ; and it appears to possess the property of passing in the circulation under the form of aethiops. The valuble ex- periments of Mr. Menghini, published in the Memoirs of the Institute of Bologna, have proved that the blood of persons who take martial remedies is thicker, and,con- tains more iron. Mr. Lorry observed that the urine of a sick person, to whom he administered iron in a state of extreme division, was manifestly coloured with the nut-gall. 116 PROPERTIES OF COPPER. CHAPTER XI. Concerning Copper. COPPER is a reddish metal, hard, elastic, sono- rous, and affording a disagreeable smell b\ friction. Its taste is stypic, and nauseous. One cubic foot of copper weighs live hundred and forty-five pounds. The specific gravity of cast copper not hammered is 7,7880. —Brisson. The alchemists distinguished 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 such that a wire of one tenth of an inch in diameter, is ca- pable of supporting a weight of two hundred and ninety- nine pounds four ounces, without breaking. This metal is capable of affecting a regular form. The abbe Mongez observed it in solid quadrangular pyramids, sometimes inserted into each other. Copper is found in various forms in the bowels of the earth. 1. Native copper.—This copper exists sometimes in leaves in a gangue of quartz. It is likewise found in compact masses at Japan. There is one of these pieces in the roy d cabinet, which weighs ten or twelve pounds. Native copper is usually disseminated in a brownish martial earth, susceptible of a polish. When this ore is rubbed with a flint, the traces appear of a beautiful cop- per-colour. Ores of this kind are found at Kaums- dorf in Thuringia.—Sage, Analyse Chimique, t. iii. p. 205. ' We have likewise found native copper at Saint Sauveur. It has the form of nodules resembling stalactites. Most ORES OF COPPER. 117 of the native coppers appear to be formed by cementa- tion, or by the precipitation of this metal dissolved in an acid, and thrown down by martial salts.* * Copper in a native state is found in the counties of York and Lancaster, Pennsylvania; in Woodbridge, .New Jersey, and on Lake Superior; and copper ore, in Berks county, Pennsylvania, and near the river Kuriton, Sew Jersey ; and a few miles from Baltimore, in Maryland ; at Hill and Haines' iron works ; on Cedar creek ; on the Past side of Broad river in South Carolina ; on the James river, Virginia, and on the Oubash. The following description of the Schuyler copper mine, drawn up by Mr. Benjamin Henry Latrobc, is extracted from the sixth volume, first hexade, p 319. of the Medical Repository of New York. "The Schuyler Copper-mine, situated betwe-ii the rivers i'assaick and Hackinsack, near their confluence, in the state of New-Jersey, was discover d about the year 1719, by A rent Schuyler, grand-father to the gentleman of that name now living? The- ore wasl'ound where it appeared on the side of the hill; was easily r.iised; and, as the policy of Pnglan ' at that time prohibited the establishment of smelting, works or manufactories in her colonics, it was packed in casks, each containing about four hundred pounds, and exported, in its state of ore, to i-jnjand. It appears by-his books, that, before the year 1731, Arent Schuy- ler had shipped 6'J.*3 casks, making about 1386 tons of raw ore, to the Bristol . opperand Brass Company. His son, Col. John Schuy- ler, prosecutec" tie work with more numerous and skilful hands. The quantity of ore raised by him is not known, as his books were lost during the war. In 1761 the mine was leased to a company who procured the assist- ance of Mr. Hornblower the uncle of the present eminent steam- engineer, from Lngland. They erected a steam-engine of the im- perfect construction then in use. The engine-house, composed of combustible materials, was soon afterwards burned down. It was, however, rebuilt, and the mine was worked for four years with great advantage and profit. In 1765 a workman who had been dismissed set fire to the engine-house. It was again destroyed, and the works were discontinued by the company. Several gentlemen in P.ngland, however, whose connexion with the company had taught them the superior quality of the ore of Schuyler's mine applied successfully to the crown for permission to establish works in America for smePing and refining copper ; and an offer was made to Mr. Schuyler to purchase the whole estate con- taining the mine, for the sum of _£ 100,000 sterling. This offer he refused, but agreed to join them in rebuilding the engine and working the mine. The disputes which arose about that time between Eng- land and America, and the consequent revolutionary war, put an end to the projected works ; and the deranged state of the country pre- vious to the adoption of the Federal Constitution in 1788, and other subsequent circumstances, occasioned the total neglect of this in every respect important mine, until the year 1793, when a company was formed, who undertook the work with new vigour. 118 SCHUYLER COPPER MINE. Mr. Sage thinks that this metal may likewise be preci- pitated from its solutions by phosphorus. To effect, says he, the precipitation of copper by phosphorus, twelve grains of this metal are to be dissolved m half a gross of nitric acid. The solution must be poured into half a pint of distilled water, into which a cylinder of phospho- rus, two inches long, weighing forty-eight grains, must be plunged. The surface becomes almost immediately black, and is covered widi particles of copper possessing the metallic colour and brilliancy. At the end of several days, octahedral crystals are seen, whose insertions into each other produce elegant dendrites; and at the end of ten days the twelve grains of copper are completely re- duced, as is proved by-pouring ammoniac into the water. Ii' it do not exhibit a blue colour, it is a proof that the fluid contains no copper. 2. Copper mineralized by sulphur forms the yellow ore of copper. They collected, at a very considerable expense, miners and smel- ters from England and Germany; purchased a freehold estate con- venient for the erection of furnaces and manufactories, with an excel- lent stream of water ; re-erected the engine ; and be^an, and partly completed the other works. At the instance of Mr. Longworthy, an active member of the company, who, to great metallurgic know- ledge and experience, and to much personal address, joined a spirit perhaps much too unbounded in its projects, and far outstripping the means and wants of our present population, an application was made to Congress, in 1796, for an exclusive right to search for and work all mines within the N. W. and S. W. territories, belonging to the United States, for thirty years. This monopoly was to descend from mines of gold and diamonds down to clay-pits and slate quarries. The application was not, and, perhaps, ought not to have been success- ful. >oon afterwards one of the proprietors of the mine, who was a principal shareholder in the company, died, and the whole interest of the company has since been purchased by Nicholas I. lioosevelt. ho other has yet been wrought to effect in North America. The ore of Schuyler's mine yields, in each hundred pounds of cop- per, from four to seven ounces of silver, and like most copper ores, a small portion of gold. At the time when pure copper was sold in Lngland at £75 sterling per ton, the ore of Schuyler's mine was ship- ped for England,at New-York, at £70 sterling per ton. This proves the uncommon richness of the ore, and the small expense of con- verting it into metal An offer has been lately made by Messrs. Bolton and Watt to purchase all the ore which can be raised, and to enter into contract for that purpose.—Am, Ed. ORES OF COPPER. 119 This ore is of a golden colour, and the ignorant are often deceived by its flattering appearance. It contains a larger quantity of copper in proportion as the sulphur is less in quantity, and gives fewer sparks with the steel. It sometimes crystallizes in beautiful octahedrons. I possess two specimens covered over with trihedral pyramids of near an inch long, and between four and five lines in diameter at the ba.-is. When the sulphur is so abundant that the proportion of copper will no longer pay for the working, the ore is called Marcasite. The marcasite crystallizes in cubes or in octahedrons, which easily effloresce. The yellow copper ore is found in various states accord- ing to the course of its decomposition. The first impres- sion of hepatic vapours colours the surface in a thou- sand shades, in which state it is known by the name of Peacock's Tail, Pigeon's Neck, &c. The last degree of alteration of this ore, effected by the simple disengagement of sulphur, forms the hepatic copper ore. The yellow colour is then converted into an obscure brown colour: this ore appears then to contain no other principles but water, copper, and iron, which last is always more or less abundant in these ores. The yellow copper ore sometimes forms sulphate of copper in its decomposition. This salt is dissolved in water, and forms springs more or less loaded with it, from which the copper may be obtained by cementation. Old iron is thrown into the water; the copper is precipitated, and the iron takes its place. In this way it is obtained in Hungary, and we might use this oeconomical process in several parts of our province. I have stalactites in my collec- tion, sent me from Cevennes, wiiich are coloured blue by a very considerable quantity of copper. In Gevaudan, at half a quarter of a league from St. Leger de Peyre, se- veral springs of water impregnated with copper are found, which run into a valley. The inhabitants of this canton drink a glass of the wrater occasionally as a purgative. The skeletons of animals are sometimes found in cop- per mines penetrated with that metal. Swedenburg has given an engraving of the figure of the skeleton of a qua- 120 ORES OP COPPER. druped taken out of a copper mine, and coloured by that metal, In the royal cabinet there is a human hand, green at the extremity of the fingers, the muscles of wiiich are dried and greenish. According to the report of Mr. Ley- el, consul of mines, there was found at Fahlun in Svye- den, in the great copper mine, a human carcase, which had remained there forty years, with the flesh and bones entire, without corruption, and without emitting any smell. The bodv was clothed, and entirely incrusted with vitriol. —Acta Literaria Suec. tri. i. anno. 1722, p. 250. The turquoise stones are merely bones coloured by the oxides of copper. Mr. D^ Reaumur, in the year 1725, gave an account to the academy of the turquoises found in Lower L r.guedoc. The colour of the turquoise fre- quently becomes converted into green, wiiich depends on the alteration of the metallic oxide. The turquoise of Lower. Languedoc emits a fetid smell by the action of fire, and is decomposed by acids. The turquoise of Prus- sia emits no smell, and is not attacked by acids. Mr. Sage suspected that the osseous part is agatized in these last. 3. Grey copper ore.—The copper is mineralized by arsenic. It lias a grey colour, and an appearance nearly vitreous, it usually contains silver ; and, when wrought to extract this precious metal, it is called the Grey Silver Ore. It affects a tetrahedral form ; and arsenic is the most predominant of its principles. 4. The grey antimonial copper ore.—This differs from the former, because it contains sulphur and antimony, and is much more difficult to be wrought. \V hen exposed to the fire, it becomes as fluid as water; the sulphur is vo- , latiiized with the antimony and the arsenic. The residue of the torrefaction is a mixture of the antimony and cop- per, and sometimes it contains silver likewise. 5. Copper ores, in their elecomposition, are reduced to a more or less perfect state of oxidation. The carbonic acid frequently unites to the metal, and becomes the mi- neralizer. This substance is known by the name of Moun- tain Blue, Azure of Copper, Mountain Green, Malachite. A. The azure of copper crystallizes in rhomboidal te- trahedral prisms, rather flattened, terminating in dihedral ORES OF COPPER. 121 summits: these crystals are of the most beautiful blue; they are frequently altered by exposure to the air, and be- come converted into malachite. Mr. Sage has imitated the azure, both in the form and colour, by dissolving copper, in the cold, in water satu- rated with carbonate of ammoniac. When the azure of copper is of a less brilliant colour, and in the pulverulent form, it is called Mountain Blue. B. The malachite, crystallized in octahedrons, has been found in Siberia. This ore is frequendy striated, formed into small tufts of a silky appearance, or in very close pa- rallel fibres. The malachite is frequently covered with protuberances. This figure appears to announce that it has been formed in the same manner as the stalactites. Mountain green differs from the malachite only in its pulverulent form, and the mixtures which alter it. The alterations of the copper ores, and native copper likewise, produce a cupreous oxide, which bears the name of Red Copper Ore. The mine of Predanah, in the county of Cornwall, has afforded the finest specimens of red cop- per ore. The metal is nearly in the metallic state, and has the form of octahedral crystals. The granular red copper ore differs from this only in its figure. It some- times has a brown martial earth for its gangue. The azure, the malachite, and the red copper require no other process but mere fusion with coal to convert them into metal; the other kinds require to be eleared of their mineralizer by torrefaction, and afterwards to be fused with three parts of black flux. To assay a sulphureous copper ore, Mr. Exchaquet proposes to make two gross of the crude ore, and one of the nitrate of potash; which, after pulverization, are to be detonated in an ignited crucible. The matter becomes hard after the detonation; upon which the fire is to be in- creased and kept up, in order that the sulphur may be dissipated. The fire is then to be still more strongly urged, until the ore enters into fusion; 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 effervescence takes place at each projection of the mixture. The fire is then to be still more strone- Vol. II. Q & 122 , WORKING OF COPPER ORES. ly raised, and the crucible covered, and kept in this state for half an hour, in ordei that the copper may flow into a mass. In this way a very malleable button of copper is obtained. 'The working of copper ores varies according to their composition. But, as the sulphureous ores are most commonly wrought, we shall confine ourselves to the pro- cess which is most suitable to their nature. The me^al is first picked or sorted; afterwards pound- ed in a mill, and washed to separate the gangue, and other foreign substances; it is then roasted, to drive off its mi- * neralizer; and afterwards fused in the blast furnace. The result of this first fusion is black copper; which is again fused in the refining furnace, to dissipate all the sulphur which has withstood the preceding operations. When it is very pure, it is poured into a broad vessel, or test; a small quantity of water is thrown on its surface, which, being by that means cooled, separates from the rest, and is taken up. This is the copper in rosettes, which is ta- ken to the hammer to be beat into proper form. The several operations are different in various places. In some coun- tries die ore is roasted as often as eight times; in others, one or two are sufficient; and in some places it is not roasted at all. This variety depends—1. On the varia- tions of practice : those who roast but little, employ more time and care in the fusion and refining. 2. On the na- ture of the ore : when it is rich in iron, the roastings arc necessary to dispose this metal to fusion. The method of roasting is likewise prodigiously va- ried. Pieces of the mineral are sometimes heaped up on a bed of combustible matter, and in this manner the calcination is performed ; but, when this ore abounds with sulphur, it may be extracted by the ingenious pro- cess used at St. Bell, and described by Messrs. Jars in their excellent work. The fusion is commonly performed in the blast fur- nace ; but at Bristol, in England, the ore is roasted in a reverberatory furnace, and fused into black copper. The refining furnace constructed at St. Bell, by Messrs. Jars, appears to me to be one of the best. They have published an excellent description of it, which mav be consulted in their Mineralogical Travels. The refining PROPERTIES OF COPPER. 123 of copper consists in depriving it of the sulphur and iron which it may still retain. The sulphur is dissi. pated by fire, and bellows properly directed; and the iron is scorified by the assistance of some pounds of lead fused with the copper. The skilful mineralogists whom I have just quoted, make use of a reverberatory furnace, lined with charcoal; and fuse and scum their copper, without using lead. When the copper contains a sufficient quantity of silver to admit of extraction, the following process is used:—1. Seventy-five pounds of copper are fused with two hundred and seventy-five of lead. The alloy is cast into flat pieces, which are called Loaves of Liqua* tion. 2. These loaves are exposed to a heat sufficient to fuse the lead, which carries the silver with it, and leaves the copper, which, on account of its being more difficult to fuse, retains the original form of the loaves; and is every where penetrated by the interstices through which the fused metal made its escape; these are called Dried Loaves of Liquation. 3. They are carried into a second furnace, where they are exposed to a stronger heat, to deprive them of the small quantity of lead which they still retain. 4. The lead is afterwards taken to the cupel, where it is fused, and separated from all the silver it had taken up. Copper is altered by long exposure to the air. Its sur- face becomes covered with a greenish coating, which is very hard, and known to the antiquarians under the name of Patin. This is the seal which attests the antiquity of statues and models covered with it. Copper, exposed to the fire, becomes blue, yellow, and at last violet. It does not flow until it is strongly ignited. When in contact with the coals, it gives a blue greenish tinge to the flame; and, if it be kept a long time in fusion, part of it is volatilized. When copper is heated in contact with air, it burns at its.surface, and becomes changed into a blackish red oxide. This oxide may be separated by striking the plate which has been ignited, or by plunging it in water. When the oxide has been pounded, and more strongly calcined, it assumes a brown red colour, and may be con- 124 PROPERTIES OF COPPER. verted into a glass of a brown colour by a more violent heat. 1. The sulphuric acid only acts on copper when concentrated, and very hot. It then dissolves it, and easily affords blue crystals of a rhomboidal form. The sulphate of copper is known in commerce by the name of Blue Vitriol, Cyprian Vitriol, Blue Cop- per, &c. Two methods are used to make the sulphate of copper which is met with in commerce. The first consists in cal- cining the cupreous pyrites, and causing them to effloresce, in order to develop the salt, which is then ex- tracted by lixiviation. The second consists in forming this pyrites artificially, burning it, and lixiviating it, to extract the salt. This salt possesses a very strong styptic taste. It is easily fusible by heat, which dissipates its water of crys- tallization, and changes its colour to a blueish white. The sulphuric acid may be extracted by a very strong fire. Lime and magnesia decompose this salt; and the precipitate is of a blueish white colour. If it be dried in the open air, it becomes green. Ammoniac likewise pre- cipitates the copper in a whitish blue: but the pre- cipitate is dissolved nearly at the same instant that it is formed; and the result is a solution of a beautiful blue colour, known by the name of Aqua Celestis. This salt contains in die quintal thirty pounds acid, forty-three water, and twenty-seven copper.* * Copper may be precipitated from the sulphate of copper by means of tin. The success of the experiment depends upon the heat of the solution, which must be at or near the boiling point, when the tin is adde I to it. Prussiate of copper is made by precipitating a solution of blue vitriol, by the prussiate of potash. It surpasses in intensity and beauty every brown paint now in use with the additional advantage that by reason of its purple tint, it forms' with white various shades of bloom or lilac colour, which do not ap- pear liable to fade, like those which are formed by means of lake. The editor of this work, prepared some prussiate of copper for Mr. Hembrandt Peale, a celebrated portrait painter of Philadelphia. The following is his opinion of this pigment. I have subjected the prussiate of copper to various trials, and have found it to be a valuable Pigment, in the fineness of its texture, quickness of drying and durability of colour, even exposed to the intense rays PROPERTIES OF COPPER. 125 2. The nitric acid attacks copper with effervesence, at the same time that it becomes decomposed, and emits abundance of nitrous gas. * W hen it is proposed to obtain this gas by the action of the acid upon the copper, it is necessary to have the precaution of weakening the acid, and to present the copper in pieces of considerable magni- tude. If these circumstances be not attended to, the acid attacks the metal with such violence as suddenly to emit a prodigious quantity of gas; immediately after which an absorption takes place, and the water of the jar passes into the bottle. In this case ammoniac is formed. The diluted nitric acid perfectiy dissolves copper: the so- lution is blue. If it be speedily concentrated, no other result is obtained but a magma without crystals; but if it be left exposed to the air, it affords crystals in ong parallelograms. By leaving a solution of this kind to spontaneous evaporation, I have obtained rhomboidal crystals, which, instead of being blue, as they are usually described, are white. They decrepitate upon the coals, emit a red gas by mere heat, and nothing remains but a grey oxide. 3. The muriatic acid does not dissolve copper unless it be boiling and concentrated; the solution is green, and affords prismatic crystals of considerable regularity when the evaporation is slow. This muriate is of an agreeable grass-green colour; its taste is caustic, and very astrin- gent : it fuses by a gentie heat, and congeals into a mass; in which the acid is so adherent, that a very strong fire of the sun, during several months. It is of a purple brown colour and therefore in combination with Prussian blue, produces a true black, of the most delicate texture and transparency. Possessing the yellow and red oxides of iron, the blue prussiate of iron, this pur- plish brown of the prussiate of copper, together with the black by combination ; we only want a white prussiate of some other metal or iron rendered white by the phosphoric or some other acid, to be in possession of a complete series of simple materials for painting not liable fo change by mutual decomposition nor the aeencv of litrht and air—Am. Ed. J fa A mixture of sal ammoniac and blue vitriol, in equal proportions dissolved in water, will produce a sympathetic ink. It is of a bright yellow colour when warm, and of a beautiful emerald green when Am £?Cn PUrC **"* concentratec!> k has no action on copper.— 126 FORMATION OF VERDIGRIS. is required to disengage it. It is very deliquescent. Ammoniac does not dissolve the oxide of this muriate with the same facility as it does that of the other cupre- ous salts. This observation was made by Mr. De Four. croy; which I think may be explained from the circum- stance that the muriatic acid suffers the copper to be precipitated in the metallic form, instead of giving out a portion of its oxigene, which would faciUtate the action of the alkali. 4. The acetous acid, when made to act either hot or cold upon copper, only corrodes it, and produces the sub- stance known in commerce under the name of Verdigris. The verdigris which is most used in the arts has been long fabricated at Montpellier exclusively. The prejudice which prevailed, that die cellars of this city alone were proper for this operation, preserved this commerce till late- ly in its hands. But the progress of information has suc- cessively put it in the power of other countries to partake in this manufacture. The process used at Montpellier consists in fermenting the refuse of grapes with sour wine.* This refuse is af- terwards laid in alternate strata, with plates of copper six inches long and five broad. In this state they are left for a certain time ; after which they are taken out, and placed edgewise in a cellar, where they are sprinkled with sour wine : in this situation the verdigris swells up ; and is af- terwards scraped off, put into sacks of leather, and ex- ported to foreign countries. Ready-made vinegar is used at Grenoble, and the plates of copper are sprinkled with it. The verdet or verdigris of Grenoble, contains one-sixth less of copper: the vinegar which is obtained is stronger and more abundant. It has not the empyreumatic smell of that of Montpellier. The copper is therefore partly dissolved in the verdet of Grenoble; because it has been first reduced into an oxide by the impression of the vinegar, and afterwards attacked by the subsequent affu- sion of the same acid. It is therefore an acetate of copper. * Vinasse. HABITUDES OF COPPER. 127 The oxides of copper, dissolved in vinegar, form a salt known by the name of Crystallized Verdigris, Crystals of Venus, Acetate of Copper. To obtain this salt, the vinasse or sour wine is distilled; and this weak vinegar boiled on the verdigris. The solu- tion 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 sticks are again taken out, covered with rhomboidal crys- stals of a blue colour. These clusters of crystals, weigh- ing each from four to six pounds, are wrapped up in paper, and distributed for sale. The vinegar may be disengaged by distillation from these crystals; and the residue is a cupreous oxide, which possesses the characters of pyrophorus. Vinegar, distilled on manganese, dissolves copper; which proves that it has taken up oxigene. The acetic acid, or radical vinegar, differs from ordinary vinegar, in containing a greater quantity of oxigene; and it is this oxigene which renders it proper to dissolve copper in the metallic state. The acetate of copper may likewise be formed by decomposing salt of Saturn, or sugar of lead, by the sulphate of copper. The sulphate of lead falls down; and the solution, when concentrated, affords the cupreous acetate. 5. The pure fixed alkalis, digested in the cold with filings of copper, become of a blue colour; but ammo- niac dissolves it much more speedily. I put copper filings into a bottle with very caustic ammoniac, and kept the bottle stopped for two years: the copper wras de- prived of its colour, and became similar in appearance t© a grey clay: whereas a similar vessel, in which I had placed the same mixture, but left open, soon afforded me very small blue cn'stals; and the whole concluded by affording only a hard stratum of green matter, resembling malachite. Copper is precipitated from its solutions by iron. For this purpose nothing more is required than to leave the iron in one of the solutions of the other metal, which need not be strong. The phenomenon may be rendered very surprising, by pouring the solution of the sulphate of 128 HABITUDES OF COPPER. copper upon the clean surface of a piece of iron; for this surface instantly becomes covered with copper. The cop- per obtained by this means, is known by the name of Copper Cementation. This precipitation of one metal by another, has given rise 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 imposed on by this pheno- menon. Copper mixes with most of the metals; and forms— 1. With arsenic, the white tombac. 2. With bismuth, an alloy of a reddish white colour, with cubic facets. 3. With antimony, a violet-coloured alloy. 4. It may be combined with zinc by fusion, or by ce- mentation with lapis calaminaris. By the first process, similor, or the Manheim gold, is obtained; die produce of the second is brass. 5. Copper, plunged in a solution of mercury, assumes a white colour, which arises from the mercury which is displaced by the copper. 6. Copper is easily united with tin; and on this de- pends the art of tinning: for which purpose it is neces- sary to clean the surface of the metal perfectly; because the oxides do not combine with the metals. This first object is accomplished by rubbing the metal intended to be tinned with the muriate of ammoniac, or by scraping it effectually; or even by passing a weak acid over its whole surface. After this operation the tin is applied by fusing it in the vessel intended to be tinned, then spread- ing it about with old rags rolled up; and the oxidation of these metals is prevented by means of pitch. Copper, fused with tin, forms bronze, or bell-metal. This alloy is more brittle, wiiiter, and more sonorous, in proportion to the quantity of tin that enters into its com- bination : it is then used to make bells. When it is in- tended to be applied to the purpose of casting statues, or forming great guns, a larger proportion of copper is used; because in this case solidity is one of the first requisites. 7. Copper and iron contract very little union. 8. Copper, alloyed with silver, renders it more fusi- ble ; and these two metals are combined to form solders. HABITUDES OF COPPER. 129 Hence it is that verdigris is occasionally observed in pieces of silver, at those parts where joinings have been made by means of solder. Copper precipitates silver from its solution in the nitric acid. This method is used in the mints to separate the silver from the acid, after the operation of parting. Copper is very much used in the arts. All the boilers in dye-houses which are intended to contain compositions that do not attack this metal, are made of copper. It is at present used as a sheathing for the bottoms of ships. All our kitchen utensils are made of it; and, in spite of the danger to which we are daily exposed of be- ing poisoned, and notwithstanding the slow and destruct- ive impression this metal cannot but produce upon us in- dividually, there are few houses from which this metal is yet banished. It is a desirable object that a law might be passed to prohibit its use amongst us; as has been done in Sweden, at the solicitation of the Baron de Schof- fer, to whom the public gratitude has erected a statue of the same metal. It is an allowable infringement of per- sonal liberty, when government take upon them to direct the conduct of individuals in such a manner as to secure their own safety. There is no year passes in which se- veral persons are not poisoned by hams, or other food which is suffered to remain in copper vessels. Tinning is not a complete remedy against this danger; for it leaves an infinity of points where the copper is un- covered*. The sulphate of copper is very much used in dying. The crystals of Venus, and verdigris, are likewise used in painting; they enter into the composition of colours, varnishes, &c. The various alloys of copper with other metals, ren- ders it highly valuable in the arts. Brass, bronze, and bell-metal, are very extensively useful. * k may besides be doubted whether the extremely thin white coating, which conceals the internal surface of tinned copper, be not a kind of bell or speculum metal, instead of tin, as it is gene- rally supposed to be. T. Vol. II. R 130 PROPERTIES OF MERCURY. CHAPTER XII. Concerning Mercury. MERCURY differs from all other metals, by its pro- perty of retaining the fluid state at the ordinary temperature of the atmosphere. It possesses the metallic opacity and brilliancy; and even acquires malleability when deprived of fluidity by a proper degree of cold. The best ascertained experiment which has been made on this phenomenon, was performed by the Academy of Petersburg, in 1759. The natural cold was increased by a mixture of snow and highly con- centrated nitric acid; and the thermometer of De Lisle was caused to fall to 213 degrees, which corresponds with 46 below 0 of Reaumur. At this period the mercury ap- peared to descend no lower: the bulb of the thermometer being then broken, the metal was found to be in a con- gealed state, and bore to be flattened by the hammer. Mr. Pallas congealed mercury, in 1772, at Krasnejark, by the natural cold: he then found that it resembled soft tin. It has been ascertained in England that the degree of its congelation was the 32d of Reaumur. Mr. Mat- thew Gutherie, consul at the court of the empress of Rus- sia, proved that the degree of cold of this congelation was 32 degrees below 0 of Reaumur; and that, when the mercury is purified by antimony, it congeals at 2 degrees lower.*—See the Journal Encyclopedique, September 1785.f Mercury is as indestructible by fire as gold and silver; and its properties in general have caused it to be arranged among the perfect metals. A cubic foot of this metal weighs 949 pounds ; and its specific gravity is 13,5681.—Brisson. * Mercury may be easily frozen, by plunging it confined in glass tubes, in a mixture of the muriate of lime and dry snow.__Am. Ed. t Por an acctunt of this subject, see Dr. Blagden's History of the Congelation of " ercury, in the seventy-third volume of the Philo- sophical Transactions. ORES OF MERCURY. 131 Mercury has been found in the earth in five different states. 1. Virgin mercury is found in most of the mines of this metal. Heat alone, or mechanical division of the ore, is sufficient to exhibit it in the metallic form. Native mercury has been found in digging the founda- tions of some houses at Montpellier; and this metal has been constantly mixed and confounded with a grey or red clay, which forms a bed almost continuous, at a few feet beneath the foundation of this town. The observations which I have had occasion to make on this subject, have ascertained that the mercury exists in a stratum of decomposed grit-stone, very argillaceous, ferruginous, and ochreous; of a red, brown, or grey co- lour. In this clay, the globules of mercury, in consider- able abundance, were easily distinguishable, lying upon greyish plates. Traces are perceived which resemble den- drites ; and its impressions are formed by layers of the oxide of mercury. Several pounds of mercury have likewise been found in a well at Vienne in Dauphiny ; and Mr. Thouvenel has pointed out to us three mines of this metal in the single province of Dauphiny, according to die indications of Bleton. 2. Mr. Sage read to the Academy, on the I lth of May 1782, the analysis of an ore of mercury, in the form of a solid oxide, which came from Idria in Friuli. It is of a brown red colour; and its fracture is granulated. It is reducible by mere heat; and affords oxigenated gas. It emits only half the quantity afforded by red precipitate; because this oxide contains metallic mercury. It affords ninety-one pounds of mercury per quintal, and a small quantity of silver. 3. The muriate of mercury, or corneous mercury, has been found native in the mine of Muschel-Lamburg, in the dutchy of Deux-Ponts. Mr. Sage obtained eighty- six pounds of mercury per quintal. Mr. Woulfe has likewise discovered, in 1776, a very ponderous white, green, or yellow crystallized ore of mer- cury ; in which he proved the existence of the sulphuric and muriatic acids. 132 ORES OF MERCURY. 4. Mercury is sometimes naturally amalgamated widi odier metals, such as gold, silver, arsenic, copper, &c. 5. Mercury is usually mineralized by sulphur; and the product is cinnabar or jethiops, according to the colour. Cinnabar is found under different forms. 1. In red crystals, consisting of two triangular pyramids, truncated, and joined base to base, or else separated by a very short intermediate prism. Cinnabar has likewise been found crystallized in transparent plates. 2. Cinnabar is almost always found in masses, more or less compact; the colour varies from deep black to die brightest red. In this last state it is distinguished by the name of Vermillion. Cinnabar has for its gangue, quartz, clay, calcareous earth, ponderous spar, and even coal. The ore which the Germans called Brandertz, has for its gangue a bitu- minous matter, which burns perfectly well; and it affords only six pounds of mercury in the quintal. The principal cinnabar mines which are wrought in Europe, are those of the Palatinate and those of Spain. Mr. Sage informed us, in 1776, of the process used in the Palatinate; and we are indebted to Mr. De Jussieu for a description of the method used in Spain. In the Palatinate, the pounded and sifted ore is mixed with one third of lime ; and the mixture introduced into iron cilcurbits, one inch thick, three feet nine inches long, one foot wide, with an opening of five inches. These vessels are disposed in a gallery. Forty-eight of these re- torts being arranged in two parallel lines, a second row is placed above the first. To the neck of each cucurbit an earthen pot is adapted, wiiich is one third filled with wa- ter, and accurately luted on. The gallery is heated at the two extremities; several apertures formed in the dome serve the purpose of chimneys ; and the distillation is ef- fected by a fire kept up for ten or twelve hours.* This process was followed at Almadan till the year 1647, when the following was adopted, as being more simple and (Economical. The furnace is twelve feet high, and four feet and a half diameter within. At the distance of five feet and a half from the ground, is an arch upcn * The editor is in possession of a specimen of Cinnabar, found jn Liberty-town, Maryland.—Am. Ed. MINE OF ALMADEN. 133 which the ore is disposed, and a fire is kindled in the ash- hole. The sublimed mercury escapes through twelve apertures formed,in.the upper part of the laboratory. To these apertures, rows of aludels, inserted one in the other, are adjusted and disposed parallel upon a terrace, which terminates in a small building separated into as many chambers as there are files of aludels. Each chamber has a cavity in the middle, to receive the small quantity of mercury which may arrive to that distance. Every furnace contains two hundred quintals of cinna- bar, and the fire is kept up for three days. The sulphur which burns is disengaged in the form of sulphureous acid, and escapes through small chimneys made in each chamber. Every repetition of the process affords from twenty-five to sixty quintals of mercury. The mine of Almaden has been wrought from time im- memorial. Its veins are from three to fourteen feet in breadth; and their breadth is even larger where they join. Hitherto no method has been discovered to fix mercury but that of extreme cold. This metallic substance, natu- rally fluid, is capable of rising even by a very moderate fire; as is proved by an experiment of Mr. Achard, wiio having left a dish containing twenty pounds of mercury over a furnace which was daily heated, experienced a sa- livation at the end of several days; as did likewise two other persons wiio had not quitted the chamber. He es- timates this heat at about eighteen degrees of Reaumur. —Journal de Physique, October 1782. It is dangerous to oppose the evaporation or dilatation of this metal which is produced by heat. In the year 1732 an alchemist presented himself to Mr. Geoffroy, pretending he had discovered the means of fix- ing mercury. He inclosed the metal in an iron box, and this box in five others, which were placed in a furnace ; the explosion was so strong, that it burst through the boards of the floor. Mr. Hellot has related a similar fact to the Academy. Mercury boils in the same manner as other liquids when it is heated; and for this purpose it does not even require a very considerable heat; the ebullition consists merely in its transition to the vaporous state : for it may be distilled like all other fluids, and by that means cleared of its impurities. Boerhaave had the patience to distil 134 CONGELATION OF MERCURY. the same mercury five hundred times successively; and the metal suffered no other change, than that it afforded a grey powder, which required only trituration to convert it again into running mercury.* Mercury is not easily changed in the air; but if the action of the air be assisted by heat, the mercury gradu- ally loses its fluidity; and at the end of several months forms a red oxide, wiiich alchemists have distinguished by the name of Precipitate per se. The apparatus made use of for this operation is a very large and very flat bot- de, closed with a stopper, in which there is a capillary perforation. The mercury within the bottle by this means possesses the contact of air ; and by disposing the appa- ratus upon a sand bath, and keeping up the state of ebul- lition in the fluid, the oxide may be obtained in the course of several months. This oxide gives out its oxigene by simple heat, with- out any intermedium; and the mercury resumes its me- tallic form ; one ounce affords about a pint. A quintal of mercury takes up about eight pounds of oxigene. The red oxide of mercury, exposed to heat, sublimes in close vessels, and may be converted into a very beautiful glass. I have observed this on all occasions when I have made the red oxide by means of the nitric acid, according to the process which I shall immediately describe. It is certain that mercury upon which water is boiled, communicates a vermifuge property to that liquid, though the most accurate experiments of Lemery have shewni that the metal does not perceptibly lose weight; which proves that the principle taken up by the water is very fugaceous, and so light that it does not constitute any sensible part of the weight. Water which has remained for a certain time over mercury contracts a very evident metallic taste. 1. The sulphuric acid does not act upon mercury un- less assisted by heat. In this case, sulphureous gas is disengaged ; and a white powder falls down, the quantity of which becomes greater in proportion as the acid is de- composed. This oxide weighs one third more than the * The boiling point of mercury is between 600° and 700° of Fahrenheit's thermometer. Dr. Irvine states it at 672*, and Mr« Dalton at 660°, and Mr. Crichton at 655°.—Am. Ed. ACTION OF ACIDS UPON MERCURY.. 135 mercury made use of. It is caustic: if hot water be poured on it, it becomes yellow; and if it be urged by, a violent heat, it affords oxigenous gas, and the mercury resumes its natural form. This yellow oxide, obtained by means of the sulphuric acid, is known by the name of Turbith Mineral. It has long been considered as a sulphate of mercury. Mr. Baume has proved that it does not contain a particle of acid; and it appears that the water wfyich develops its yellow colour, seizes the small quantity of undecomposed acijl which was mixed with the oxide. If the water which has been poured on it be evaporated, a salt is obtained in small, soft, and de- liquescent needles, which may be deprived of their acid by the simple affusion of water. This fluid precipitates the mercury from them in the form of turbith.* 2. The nitric acid of commerce, at the strength of thir- ty-five degrees, dissolves mercury with violence, even without the assistance of heat. This solution is accom- panied with the disengagement of a considerable quantity of nitrous gas; because it is necessary that the acid should reduce the metal to the state of oxide before it can act upon it. One part of the acid is consequently em- ployed in disposing the metal for solution, and the other dissolves it in proportion as it is oxided. This is what happens when the sulphuric acid is digested upon a me- tal ; one portion is decomposed, and reduces the metal into an oxide, while the other dissolves it. The manner of effecting the solution of mercury in the nitric acid, has an influence on the properties of the mer- curial nitrate. Bergmann has observed that the solution which is made slow'y and quietly, without disengagement of nitrous gas, affords no precipitate on the addition of water; whereas that which is made by the assistance of * Turbith mineral is a sulphate of mercury. If it is boiled ever so often in distilled water, the water will pre- cipitate the muriate of barytes. If potash is digested with it, vitri- olated tartar, or sulphate of potash will be formed. If it is exposed to a red heat in a glass tube, oxigene gas will be procured, and sulphate of mercury of a white colour will sublime, and adhere to the sides of the tube. The editor has proposed to employ a calx of mercury, prepared by boiling a solution of potash on turbith mineral, in order to pro- cure oxigene gas, perfectly pure, is no azotic air can be procured, from an oxide prepared in this manner.—Am. Ed. 136 MERCURIAL SALTS. heat, and with loss of nitrous gas, affords a precipitate. It appears that the nitric acid, assisted by heat, is capable of becoming loaded with an excess of mercurial oxide, which it lets fall when diluted with water. The method of performing the solution, and the pro- cess made use of to crystallize it, has an equal influence upon the form of the crystals. 1. The solution made in the cold, and left to spontaneous evaporation, affords cry- stals which appeared to Mr. De Lisle to be octahedral py- ramids, truncated near their base, and having the four angles resulting from the junction of the bases of their pyramids likewise truncated. 2. If the same solution be evaporated, long and acute blades are obtained, laying one upon the other, and striated obliquely across. 3. The solution of mercury effected by heat, affords flat and acute needles, striated lengthways. The nitrate of mercury is corrosive; it detonates upon coals when it is very dry, and emits a whitish flame of considerable brilliancy. The mercurial nitrate, heated in a crucible, is fused, and emits a considerable quantity of nitrous gas together with its water of crystallization. The remaining oxide becomes yellow; and at length assumes a lively red co- lour, and fonns the substance called Red Precipitate. In order to make a very fine red precipitate, the mercurial solution must be put into a retort, and distilled until no more vapours come over. An additional quantity of ni- tric acid must then be poured on the remainder, and like- wise distilled off. After three or four repeated distilla- tions, a very beautiful precipitate is obtained in small cry- stals of a very superb red colour. The solution of mercurial nitrate forms mercurial wa- ter. It is of use to ascertain the presence of sulphuric and muriatic salts in mineral waters. The acids, the alkalis, the earths, and some of the me- tals, likewise precipitate mercury from its solution in the nitric acid. These precipitates always consist of the ox- ides of mercury in a greater or less degree of perfection, according to which circumstances their colour is subject to variation. On this head, Lemery, Baume, &c. may be consulted. Mr. Bayen has discovered that some of these precipi- tates possess the property of fulminating, when mixed FULMINATING MERCURY. 137 with a small quantity of sublimed sulphur. This che- mist has pointed out three—1. The precipitate of'mercu- ry from its solution in the nitric acid by the assistance of the carbonate of ammoniac. 2. The precipitate of the same fluid by lime-water. , 3. The precipitate of the so- lution of corrosive sublimate by lime-water. Half a gross is to be triturated with six grains of sublimed sulphur. After the detonation, a violet coloured powder remains, which affords a fine cinnabar by sublimation.* * Howard's fulminating mercury is prepared in the following manner: Dissolve one hundred grains of mercury, in one ounce and a half of nitric acid by measure. Pour the solution when cold into two ounce measures of alkohol. Apply the heat of an Argand lamp, until an effervescence takes place, when a precipitate will be formed, which is to be immediately collected on a filter, well wash- ed in pure water, and dried in a heat not exceeding that of a water bath. One hundred grains of mercury, will yield one hundred and thirty of the dry precipitate Brugnatelli informs us, that this fulminating compound may be prepared without heat, by pouring upon Turbith mineral, about four times its weight of alkohol, and five times its weight of nitric acid. An effervescence will take place, and what remains behind will be fulminating mercury.* The editor has prepared this compound, by dissolving the cry- stals of the nitrate of mercury in water, adding alkohol to the so- lution, and then the nitric acid. An effervescence took place in the cold, and the fulminating mercury was deposited in the* form of a white powder. This preparation can be fired with the flint and steel. The flash is quicker and more vivid than that of gunpowder. A train of it several inches in length, is consumed in a single instant. It maybe fired by an electrical shock. No gun can confine a quantity of it, sufficient to project a bullet, with a greater force, than an ordinary charge of gunpowder. Ten grains of it is sufficient to destroy the best pistol barrels, which cannot be burst by filling them full of gun- powder. A few grains of it, placed upon an anvil, and struck with a hammer, explodes with a sharp and loud noise. The editor had a quantity of this preparation in an ounce vial, ly- ing upon a table. The walking of a few gentlemen through the room, caused it to explode. Having placed a few grains on a copper plate, he laid a golden eagle, or ten dollar piece over them, and applied the heat of an Ar- gand lamp to the bottom of the plate, to flash the powder. The gold was placed over the fulminating compound, to shew that the mercury was revived when it was fired. When the flash took place, • Philosophical Magazine, vol. xvi. p. 186. Vol. II. S 138 CORROSIVE SUBLIMATE. 3. The muriatic acid does not sensibly act upon mer- cury : but if it be digested for a long time upon the me- tal," it oxides it, and at length dissolves the oxide, as may be concluded from the exjreriments of Homberg, inserted in the volume of the Academy of Sciences for the year 1700. The muriatic acid completely dissolves the mercurial oxides. When these oxides are nearly in the metallic state, or charged with a sm?ll quantity of oxigene, the muriate of mercury is formed. When, on the contrary, the oxide of mercury is saturated with oxigene, the oxigenated muriate of mercury, or corrosive sublimate of mercury, is formed. Corrosive sublimate may be 'formed according to two methods; in the dry way, or in the humid way. To make this salt in the dry way, the operator may proceed in various manners. 1. Equal parts of dried nitrate of mercury, decrepi- tated muriate of soda, and sulphate of iron calcined to whiteness, are mixed together. This mixture being ex- posed to sublimation, the product which arises is cor- rosive sublimate. 2. Running mercury is used in Holland instead of the nitrate of mercury; and the same results may be obtained by using any oxide of mercury whatever. 3. Equal parts of the sulphate of mercury, and the decrepitated muriate of soda, afford the same salt by sublimation. This process of Kunckel has been revived by Boulduc. 4. Mr. Monet assures us that he obtained corrosive sublimate by treating the dry muriate of soda, and a mercurial oxide, in the way of distillation in a retort. If mercury be dissolved in the oxigenated muriatic acid, the solution, when concentrated, affords vuy fine the copper was perforated, the eagle bent in various directions, and thrown against the ceiling, where it made a large hole. The principal agents by which fulminating mercury produces its effects, are gas, and caloric very suddenly set at liberty, and mer- cury and water thrown into a state of vapour. Mr. Howard supposes this preparation is composed of nitrous etherized gas, aBd oxalate of mercury, with excess of oxigene.__ Am. Ed. CORROSIVE SUBLIMATE. 139 corrosive sublimate. It may likewise be obtained by pre- cipitating the mercury from mercurial water by the same acid, and evaporating the solution. I have obtained very fine sublimate by presenting a mercurial oxide, sufficiently loaded with oxigene, to the ordinary muriatic acid. One pound of muriatic acid, at the strength of twenty-five degrees, poured upon one pound of red oxide by the nitric acid, discolours it, in a short time dissolves it with a violent heat; and this solution, diluted with water, and properly evaporated, affords from twelve to fourteen ounces of crystals of corrosive subli- mate. The corrosive muriate of mercury has a styptic taste, followed by an exceedingly disagreeable metallic taste. When placed on hot coals, it is dissipated in fumes; when slowly heated in subliming vessels, it rises in pris- matic crystals, so much flattened, that their faces are scarcely distinguishable. The assemblage of these has induced authors to compare them to sword blades lying across each other. This salt is soluble in nineteen parts of water; and when the solution is concentrated, it affords crystals simi- lar to those obtained by sublimation. Barytes, magnesia, and lime decompose this salt. Half a gross of corrosive sublimate in powder, thrown into a pint of lime-water, forms a yellow precipitate. This flu- id is known by the name of Phagedenic Water. Fixed alkali precipitates the mercury in an orange-co- loured oxide; and volatile alkali in the form of a white powder, which becomes brown in a short time. The same muriatic acid, combined with a less perfect oxide of mercury, forms the mild muriate of mercury, or mercurius dulcis. This combination may likewise be made by two methods; by the dry, or the humid way. 1. In the dry way, four parts of corrosive muriate of mercury are triturated in a mortar with three of running mercury. When the mercury has disappeared, die mix- ture is put into phials, and sublimed three successive times, in order that the combination may be more accu- rate. This sublimate differs from corrosive sublimate by its insolubility in water, its insipidity, and the form of its crystals, which are tetrahedral pyramids, terminated by 140 MERCURIUS DULCIS. four-sided pyramids. To obtain this regular form, it is necessary diat the sublimation should be made at a moderate heat; for, if the heat be sufficient to liquefy the salt, the result is merely a crust, with no appearance of crystals. As the trituration of corrosive sublimate is dan- gerous, on account of the powder which rises, Mr. Baume pours a small quantity of water upon the mixture. This liquid accelerates the trituration, and prevents the rising of the destructive powder. Mr. Bailleau has proposed the incorporating of corro- sive sublimate with water, and triturating it with running mercury. The combination is completed by digesting the mixture on a sand bath by a gentle heat. The matter becomes white, and requires only a single sublimation. Whenever it is suspected that mercurius dulcis still retains a portion of corrosive sublimate, nothing more is neces- sary to be done than to triturate it, and pour boiling water upon it: for by this means the whole of the soluble salt which may have remained, is carried off.* Mr. Baume has proved that there is no intermediate state between mercurius dulcis and corrosive sublimate. If less mercury be added to the sublimate, a proportional quantity of mercurius dulcis only sublimes, and the rest rises in the form of corrosive sublimate; if a greater quan- * The following method of preparing calomel is recommended by the Editor. Put any quantity of crude mercury into an iron pot, and add to it an equal quantity of sulphuric acid. Boil the acid over the mercury, until a dry salt remains in the pot; reduce this to a fine powder, and mix it accurately with an equal quantity by weight of sea salt, dried over the fire. 1-ill oil flasks about two thirds full of this mixture ; or glass sub- liming vessels, similar to the one in plate ii. The bottoms of these vessels should be eleven inches broad and very thin, the tops four inches from the bottom, and the neck three inches high. Expose these vessels in a sand bath, to a considerable degree of heat for,several hours, and corrosive sublimate will be obtained, and found adhering to the upper sides of the glass vessels. Reduce this to a fine powder, and triturate every pound of it, with eight ounces of crude mercury, until the globules of this metal"disappear, then sub- lime. Calomel may also be procured by adding fluid mercury, to the mixture, of sea salt and sulphate of mercury, and triturating them together, andonce subliming them. The heat must approach to red, and the bottoms of the flasks will frequently be found melted. Several thousand weight of calomel have been prepared in this city, in this manner.—Am. Ed. MERCURIUS DULCIS. 141 tity of mercury be added than is necessary to convert the whole into mercurius dulcis the excess remains in the form of running mercury. The same chemist has likewise proved, that a portion of the mercury is always lost at each sublimation; and that a small quantity of corrosive sublimate is formed, which arises from the alteration of the mercury. Hence it follows that the mercurial panacea, which is made by subliming mercurius dulcis eight or nine times, is a more suspicious remedy than the mercurius dulcis itself. 2. Mercurius dulcis may likewise be made by decom- posing mercurial water by a solution of the muriate of soda. The white precipitate wiiich 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 corrosive muriate of mercury differs therefore from the mild muriate by the state of its acid. The mercurial oxides are equally soluble in the other acids. 3. A solution of borax, mixed with mercurial water, forms a very abundant yellow precipitate, which is nothing else but the combination of the acid of borax and mercury. A small quantity of this salt remains in solution, which may be obtained in brilliant crystals by evaporation. 4. The acetous acid likewise dissolves the oxide of mercury, and affords white foliated crystals. Mercury precipitated from a solution of the acetate of mercury, combines with the acidulous tartrite of potash, and forms vegeto-mercurial water of Pres- savin. The acetate of mercury is the basis of Keyser's pills. J 5. Mercury, artificially mixed with sulphur, forms the red or black sulphures, known, on account of their colour, by the names of .Ethiops or Cinnabar. To form the sethiops, or black oxide of mercury, three methods may be followed. 142 MERCURIAL iETHIOPS. 1. Four ounces of mercury may be triturated with twelve ounces of sublimed sulphur in a glass mor- tar. The result is a black powder, called iEthiops Mineral. 2. Four ounces of sulphur may be fused in a crucible, and one ounce of mercury extinguished in it. The mix- ture readily takes fire, but the inflammation is to be pre- vented ; and the blackish residue being pounded, affords a greenish powder, which is a true aethiops. 3. The aethiops may be made by pouring the sulphure of potash upon mercurial water. These aethiops afford by sublimations cinnabar, or the red sulphurated oxide. But in order to make it with a greater degree of accuracy, four ounces of sublimed sul- phur are fused in an unglazed earthen pot, and one pound of mercury mixed with it by stirring or agitation. When these substances 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 residue pulverized, which forms a violet powder, usually weighing about seventeen ounces five gross. 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 filings, afford very pure mercury by distillation, wiiich is called mercury revived from cinnabar. Lime, the alkalis, and most of the metals, may be substituted instead of the iron. Mercury amalgamates with most other metals. On this property is founded the art of water-gilding, or gilding upon metals, the tinning of glasses, the working of gold and silver mines, &c. Mercury is likewise used in the construction of meteorological instruments, in which it possesses the advantage over other fluids—1. That it does not easily freeze. 2. It is more easily and gradually dilatable, ac- cording to the fine experiments of Messrs. Bouquet and Lavoisier. 3. It is very nearly of the same quality in different specimens. Mercury may be used in substance as a remedy against the volvulus, and it has never been observed to produce CHARACTERS OF SILVER. 143 bad effects. It is mixed with fat, to form unguents very much used in venereal cases. These are prepared with one-third or half their weight of mercury, according to the exigence of the case. The mercurial water is used as an escharotic. The red oxides answer the same purpose. The mild mercurial muriate is used as a purgative. It enters into the composition of pills which are used in venereal cases, with the intention of carying off the mor- bific matter by the skin. The corrosive muriate of mercury is of verv extensive use, more especially against venereal disorders. This remedy requires skill and prudence ; but I have received it as the common opinion of all physicians of reputation that it is the most powerful and certain remedy possessed by the art of medicine. In a large dose it irritates the system, affects the stomach, occasions spasms in the lower belly, and leaves impressions which are difficult to be eradicated. Cinnabar is used in fumigations, to destroy certain in- sects which attach themselves to the skin. It is likewise used as a pigment. CHAPTER XIII. Concerning Silver. SILVER is a metal of a white colour, possessing neither smell nor taste, nearly unalterable by fire, verv ductile and tenacious. A cubic foot of this metal cast. weighs seven hundred and twelve pounds; the specific gravity of cast silver is 10 1752. See Brisson.—It is found in the earth in five different states, which we shall proceed to consider. 1. Virgin or native silver.—Native silver is found in various forms. 1. In ramifications composed of octa- hedrons inserted one in the other. This variety is known by most mineralogists under the name of Virgin Silver 144 NATIVE SILVER. in Vegetation. Four processes, indicated by Mr. Sage, are known for the crystallization of silver: amalgama- tion, reduction by phosphorus, reduction by copper, and fusion. A detail of these four processes may be seen in his Analyse Chimique, book iii. p. 238, et seq. Native silver is likewise found in small capillary, flexible, and intertwined threads. The decomposition of the red or vitreous silver gives rise to this species; it may even be produced by a slow calcination of one of these ores. Silver is likewise found in irregular forms; either in small plates dispersed in the gangues, or in masses. Albinus reports in the Chronicle of the Mines of Misnia, that in the year 1478 a lump of native silver wras found at Sehneeburg, weighing four hundred quintals. Duke Albert of Saxony descended into the mine to see diis surprising mass of silver, and had dinner served up upon it. 2. The vitreous silver ore, or silver mineralized by sulphur.—This ore is of a grey colour, and may be cut like lead. It crystallizes in octahedrons, or in truncated cubes, and is most frequently found of an indeterminate figure. The sulphur may be extracted by heat. It affords about sixteen pounds in the quintal. When the sulphur is contained in a greater pro- portion in this ore, it becomes black, porous, and friable. 3. Red silver *ore: silver mineralized by sulphur and arsenic.—This species crystallizes in hexahedral pyramids, terminating in an obtuse trihedral pyramid, with rhombjc faces. It is frequently found in irregular masses of no' determinate figure. It possesses the colour and transpa- rency of the ruby. Mr. Sage has obtained from this ore, by distillation, water, carbonic acid, and the sulphurated yellow and red oxides of arsenic. If this ore be calcined in a test, and the mineralizer be suffered to exhale, the residue is found to be in the metallic state, exhibiting contorted threads of silver at its surface. Part of the silver passes to the state of grey oxide in this operation. ORES OF SILVER. 185 4. White antimonial silver ore : silver and antimony mineralized by sulphur.—This ore is as white as silver; it is brittle, and of a granulated fracture. Sometimes it is found in hexahedral prisms, truncated and flat at each end: this kind is found in the principality of Fur- stenburg. When exposed to heat, it becomes as fluid as water, emits antimony and sulphur, and leaves the silver behind, together with an oxide of antimony. This semi- metal is cleared off by fusion, assisted by proper fluxes, and cupellation. 5. The corneous ore of silver, or muriate of- silver.— This species is of a dirty yellow grey : it is soft, and may be easily broken or cut. A gentle heat causes it to flow: it sublimes without decomposition, is most fre- quently found of no regular form, but sometimes crystal- lized in cubes. The muriatic acid is its mineralizer. Mr. Woulfe has shewn that it likewise contains a small quantity of sulphuric acid. 6. Silver is also very frequently alloyed with various metals, such as lead, copper, bismuth, cobalt; and these ores are sometimes wrought on account of the quantity of silver they contain. The manner of working a silver ore varies according to its nature; but all the processes used in various coun- tries may be reduced to the following: 1. In Peru and Mexico the mineral is pounded, roasted, washed, and afterwards triturated with mercury in copper boilers filled with water kept at the boiling heat. The whole is agitated bymeans of a kind of mill. The amalgam is afterwards expressed in a skin; then heated to drive off the remaining mercury; after which process the silver remains alone. This method is defective—1. Because the fire volatili- zes a portion of the muriate of silver which abounds in these ores. 2. The washings carry with them a portion of the oxide of silver. 3. The mercury does not amal- gamate either with the muriates of silver, or the sulphates of that metal. 2. When silver ores, mineralized by sulphur or arsenic, are to be wrought, they are roasted, pounded, washed, and fused with lead. This metal seizes Vol. II. T 186 • ALLOY OF SILVER. all the silver, from wiiich it is again separated by cupellation. 3. When the silver ore is poor, it is fused with cupre- ous pyrites, and the mixture treated in die way of liqua- tion. —See the article Lead. To determine the degree of purity of die silver, a given weight of silver is supposed to b,e composed of twelve parts, called pennyweights; each pennyweight is divided into twenty-four grains. Silver, clear of all mixture, is said to be twejve pennyweights fine. In order to assay silver, and to ascertain its degree of fineness, the regulation of the Court of Monies of France prescribes, that thirty-six grains of silver be taken, and wrapped in a plate of lead containing no fine metal, and then exposed to cupellation. From the loss which the button of silver that remains on the cupel has suffered, a judgment is made of the quantity of alloy. If the loss be one twelfth of the whole, the silver is said to be eleven pennyweights fine. The details relating to this operation may be seen in UArt d?essayer VOr et VArgent, par M. Sage. Silver may be rendered hard by mixing it with copper; and for this reason it is alloyed with that metal for silver- smiths wrork, as wrell as for the coinage. The law permits one twelfth of alloy in silver money ;* and it is this por- tion of copper which renders the solution of silver coin in the nitric acid blue. Silver is not changed by the contact of air. A con- siderable heat is required to fuse it; but it may be vola- tilized by strong 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 exposed immediately over it. Junker converted silver into glass, by treating it in a way of reverberation, after the manner of Isaacus Hol- landus, in a very strong fire. * The British coinage is 11 ounces 2 pennyweights fine. T. HABITUDES OF SILVER 187 Macquer, by exposing silver twenty times successively to the porcelain furnace of Seves, obtained glass of an olive green colour. It was likewise observed that this metal, when exposed to the focus of a burning mirror, presented a white puiverulent matter on its surface, and a greenish vitreous covering on the support upon which it was placed. Though these experiments clearly prove that silver is capable of combining with oxigene, the difficulty which is found in effecting this combination, and the facility with which this air is disengaged from the oxides of silver, prove that there is but little affinity between these two substances. If silver in a state of extreme division be presented to the concentrated and boiling sulphuric acid, sulphureous gas is disengaged: the silver is reduced into a white mat- ter, which is a true oxide of silver; and contains a small quantity of sulphate, which may be obtained in small needles, or in plates formed by the union of these needles, lengthways, as Mr. De Fourcroy has observed. This salt flows by heat, and is very fixed. If silver be pre- cipitated by metals or alkalis, these precipitates are reduci- ble without addition. The nitric acid dissolves silver with rapidity: much nitrous gas is disengaged.* The solution is at first blue: but this colour disappears when the silver is pure; and degenerates into a green colour, if it be alloyed with copper. The nitric acid is capable of dissolving more than half its weight of silver. The solution then lets fall crystals in hexagonal, triangular, or square plates, which are called Nitrate of Silver, Lunar Crystals, Lunar Nitre, &c. The solution of these crystals, generally known by the name of Solution of Silver, is very caustic. It colours the skin black, burns the epidermis, and so completely destroys its organization, that the spot disappears only by the renewing of the skin. * When pure and concentrated it has no action on this metal. —-Am, Ed. 188 HABITUDES OF IRO.\. The nitrate of silver melts on burning coals; but if it be exposed to a gentle heat, in earthen or metallic vessels, it liquefies, and may then be cast in moulds. This fused nitrate of silver forms the lapis infernalis. Care must be taken to pour it out as soon as it is fused; because other- wise the acid would be disengaged, the silver would be revived, and the lapis infernalis, or lunar caustic, would lose its virtue. Lapis infernalis, made with pure silver, and pre- pared as above described, is whitish; wiiereas it is blackish when suffered to remain in fusion for any time. Lapis infernalis is very frequently mixed with nitrate of copper. This fraud is reprehensible, be- cause it is an alloy which renders wounds of a bad character. The lapis infernalis is used as an escharotic, and to cor- rode fungous excrescences. Silver may be precipitated from its solution by lime- water, alkalis, and several metals. These last exhibit very important phenomena. 1. A plate of copper, immersed in a solution of silver diluted in water, precipitates the metal. It adheres at the moment of precipitation to the surface of the copper, where it forms a kind of moss. In proportion as the silver is precipitated, the water assumes a blue tinge; which proves that the copper is dissolved in the nitric acid, in the room of the silver. When the whole of the silver is disengaged, the water is to be decanted, the silver dried, and fused in crucibles, to be cast into ingots. This silver almost always retains a small quantity of copper; of wiiich it may be deprived by cupellation with lead, which ren- ders the silver pure : this process is used in the mints, where die parting operation of gold from silver is per- formed. The first step consists in separating the silver by means of nitric acid; and this is afterw ards precipi- tated by the addition of copper. HABITUDES OF SILVER. 189 2. The silver is likewise precipitated by mercury. In this operation it amalgamates with a small quantity of the mercury, and forms tetrahedral crystals terminated by a tetrahedral pyramid, which crystals are articulated into each other. This arrangement gives them the form of a vegetation; and has caused the precipitate to be known by the name of the Tree of Diana, Arbor Diance. Le- mer), Homberg, and other chemists, have successively published processess to produce this phenomenon; but that which has succeeded best in my hands, is described by Mr. Baume. Six gross of the solution of silver, and four of that of mercury, both well saturated, are taken, and diluted with five ounces of distilled water. These are to be put into a conical vessel; and an amalgam of seven parts of mercury, and one of silver, is to be poured in. A multitude of small crystals instantly appear to dis- engage themselves from the surface of the amalgam, upon which new ones articulate themselves; and a vegetation is produced, which perceptibly rises under the eye of the spectator. To render this phenomenon more striking, I decant the exhausted water, and substitute fresh: by this means I can fill any vessel whatever with these vegetations. The mercury amalgated with the sil- ver, in this operation, may be separated bv means of fire. The muriatic acid does not dissolve silver, but it speedily dissolves its ox'^les. The oxigenated muriatic acid dissolves silver. To produce a certain and speed)- combination of the muriatic acid with silver, this acid is to be poured into a solution of the nitrate of silver. A precipitate immedi- ately falls down, which is known by the name of Lima Cornea. This muriate of silver is very fusible; and runs into a grey and transparent substance, considerably re- sembling horn. If a stronger degree of heat be applied it is decomposed, part is volatilized, and the other part reduced into silver. l The muriate of silver, exposed to the light of the sun becomes brown in a short time. Oxigenous gas is disen' gaged; which may be collected by placing it under water, according to the process of Mr. Berthollet 190 FULMINATING SILVER. Most of the solutions of the metals have die same pro- perty. Lunar nitre likewise becomes coloured, and emits its oxigene and nitrous gas. One pound of boiling water does not dissolve more than three or four grains of muriate of silver, accord- ing to the observation of Mr. Monnet. The alkalis are capable of decomposing the muriate of silver, and separating the metal. The silver may be disengaged from its muriate by fusion with three parts of black flux. Mr. Berthollet has taught us the following process, to form the most dreadful and the most astonishing fulmi- nating powder we have yet been acquainted with, Take fine silver of cupellation; dissolve it in nitric acid j precipitate this solution by lime-water; decant the water, and expose the oxide for three days to the air. Mr. Berthollet is of opinion that the presence of light has some influence in the success of this experiment. Mix this dried oxide in ammoniac, or volatile alkali, and it will assume the form of a black powder: decant the fluid, and leave the powder to dry in the open air. This is the fulminating silver.* Gunpowder, and even fulminating gold itself, cannot be compared with this new product. The contact of fire is necessary to cause gunpowder to detonate ; and a deter- * This black powder, which has b*»:n represented by systematic writers as the fulminating compound, has no such property, any fur- ther than maybe owing to the matter deposited from the alkaline so- lution, during the exsiccation. The alkaline liquor containing the fulminating silver ought to be poured off from the insoluble powder, and exposed in a shallow ves- sel to the air. In consequence of the exhalation, black shining crystals form on the surface only, and soon join to form a pellicle. As this pellicle adheres a little to the sides of the vessel, or maintains its figure, the liquor may be pouredoff by a gentle inclination of the vessel. This liquor will yield another pellicle in the same way, but the third or fourth pellicle will be paler than the former, and \u-v.ker in the explosion. The first pellicles, when slowly dried, explode by the touch of a feather, or by their being heated to 90° of Fahrenheit's tnermo- meter.*— Jm. Ed. • Minutes of the Society for Philosophical experiment* and conversations, p. J27. FULMINATING SILVER. 181 minate degree of heat is required to cause fulminating gold to fulminate : but the contact of a cold body is sufficient to produce the detonation of fulminating silver. In a word, this product, once obtained, can no longer be touched: no attempts must be made to inclose it in a bottle, but it must be left in the capsule wherein die eva- poration was performed. It is useless to observe, that the fulmination ought not to be attempted but with small quantities; the weight of a grain, for example : for a (larger mass wrould give rise to a dangerous detonation. The ne- cessity of making this preparation with the face covered with a mask with glass-eyes, may be easily conceived. It is prudent to dry the fulminating silver in small metal- lic capsules. The following experiment will complete the notion which ought to be formed of the fulminating property of this preparation. Take the ammoniac which was used in the conversion of the oxide of silver, into the black precipitate which forms fulminating silver: put this ammoniac into a small matrass of thin glass, and let it be subjected to the de- gree of ebullition necessary to complete the combination. Take the matrass from the fire; and a rough covering of crystals will be formed on its internal surface which is beneath the fluid. If one of these crystals beneath the cold fluid be touched, an explosion takes place which breaks the matrass. The process for obtaining fulminating silver being de scribed, its effects known, and the cautions necessary for repeating the experiment being well ascertained, we shall speak a word concerning the theory of the phenomenon: it is the same as that of fulminating gold, laid down by Mr. Berthollet.—See the memoirs of the Royal Academy of Sciences, for the year 1785. In this operation, the oxigene, which adheres very slight- ly to the silver, combines with the hydrogene of the am- N moniac. From the combination of the oxigene and the hydrogene, water in the state of vapour is produced. This water, instantly vaporized, and possessing all the elasticity and expansive force of that state, is the principal 192 FULMINATING SILVER. cause of the phenomenon ; in which the nitrogene, which is disengaged from the ammoniac, with its whole expan- sibility, likewise bears a principal part. After the fulmination, the silver is found reduced or revivified; that is to say, it has resumed its metallic state. It again becomes the same white, brilliant, and pure me- tal which it was when taken out of the cupel.* The principal use of silver is in coinage, as the repre- sentative sign of the value of other commodities. Its metallic brilliancy has caused it to be adopted as an ornament; its hardness, and unchangcableness in the air, renders it very valuable. It is alloyed with copper, to form solder; wiience it happens that silver utensils are subject to rust and verdi- gris, at the places where they are soldered. * Brugnatelli's mode of preparing a fulminating oxalate of silver is as follows. " Take 100 grains of lapis infernalis in powder, and having put them into a beer glass, pour over them first an ounce of alcohol, and then as much concentrated nitric acid. The mixture becomes heat- ed, enters into ebullition, and there is visibly formed ether, which is changed into a gaseous fluid. The matter gradually becomes milky and opaque, and is filled with small very white flakes : when the whole gray powder of the lapis infernalis has assumed this form, and when the liquor has acquired consistence, you must immediately add distilled water to suspend the ebullition, and to prevent the mat- ter from being re-dissolved, so that nothing may be found but the solution of silver. Then collect the white precipitate on a filter, and suffer it to dry. This precipitate is fulminating silver: a little more than half the weight of the lapis infernalis employed is ob- tained. The detonating force of this preparation even in a much smaller quantity far surpasses that of fulminating mercury prepared according to the process of Mr. Howard. It detonates in a terrible manner when scarcely touched with a glass tube the extremity of which has been dipped in concentrated sulphuric acid, or even that of the shops. A grain of this fulminating silver put upon a burning coal made so loud a report that it stunned the by-standers. The same effect was produced by putting a little of the same preparation on an electric pile, with a piece of paper interposed, and making a spark pass through the middle of it by means of a metallic plate : the paper will be either perforated or torn."^w. Ed. PROPERTIES AND ORES OF GOLD. 153 CHAPTER XIV. Concerning Gold. GOLD is the most perfect, the most ductile, the most tenacious, and the most unchangeable, of all the known metals. A cubic foot of pure gold, cast and not hammered, weighs 1348 pounds; and its specific gravity is 19,2581.—See Brisson. Gold has neither smell nor taste ; its colour is yellow, and this varies according to the purity of the metal. 1. As gold is subject to very little alteration, it is al- most always found in the native state; and under this form it exhibits the following varieties :—1. It is found in oc- tahedrons in the Gold mines of Boitza in Transylvania. These octahedrons are sometimes truncated in such a manner as to have the appearance of hexagonal plates. This native gold is alloyed with a small quantity of silver; which, according to Mr. Sage, gives it a pale yellow co- lour. It has likewise been found crystallized. in tetrahe- dral prisms, terminated by four-sided pyramids. The amalgam made with certain precautions is likewise capa- ble of causing gold to assume a form nearly similar, ac- cording to Mr. Sage; and gold reduced by phosphorus sometimes exhibits octahedral crystals. Gold likewise crystallizes by fusion. Messrs. Tillet and Mongez obtained it in short quadrangular pyramids. 2. Native gold sometimes exhibits fibres or filaments of various lengths; it is likewise found in plates disse- minated on a gangue. The gold ore of Lagardet, a few leagues distant from Alemont in Dauphiny, is of this kind. 3. Gold is likewise found sometimes in small plates or spangles, dispersed in sand or earths: under this form it is found in the auriferous rivers, such as the Ariege, the Ceze, the Gardon, the Rhone. These small plates are Vol. II. U 154 ORES OF GOLD. sometimes one line in chameter, but most comnwmly too small to be seen by the naked eye. 4. Gold is sometimes found in irregular masses; in which instance it is known by the name of Gold Dust. Very large pieces of this kind are found in Mexico and Peru. 3. Gold is sometimes mineralized by sulphur, by the means of fire. The auriferous pyrites are frequently found in Peru, Siberia, Sweden, Hungary, &c. To as- certain whether a pyrites contains gold or not, it must be pounded, and nitric acid poured upon it until it takes no- thing more up. This solution must then be diluted with much water. The lightest insoluble parts may be carried off by washings ; and the residue, upon examination, will shew whether it contains gold or not. When the martial pyrites is decomposed, the gold is al- ways disengaged; and" it is probable that the small plates of gold in the auriferous rivers, are afforded by a decom- position of this kind. Gold is sometimes mineralized by sulphur, with the assistance of zinc, as in the gold mine of Nagyag. This ore likewise contains lead, antimony, copper, silver, and gold. 4. Mr. Sage has given a description and analysis of an arsenical ore of gold.* 5. Gold likewise exists naturally in vegetables. Be- cher obtained it. Henckel affirmed that they contain it; and Mr. Sage lias resumed this inquiry, and found it ac- * Mr. Jefferson informs us, that he knew a single instance of gold found in Virginia, on the north side of the Rappahannoc river, a- bout four miles below the falls. It was interspersed in small specks, through a lump of ore,'of about four pounds weight, which yielded seventeen penny-weights of gold, of great ductility.* Drayton says, a small bit of gold is' said to have been once found in Greenville district, on Paris mountain, South Carolina, of suf- ficient quantity to be made into a ring.f But the largest quantity of this metal in North-America, was dis- covered m 1803, m Cabarrus county, North-Carolina. It is found in a creek, which m the summer is dry, in small grains and consi- derable masses^ 1 he gold is mixed with black sand, schistus, quartz, and granite Near twenty thousand dollars worth of this metal have been coined at the mint in Philadelphia.__Am. Ed. * Jefferson's Notes on Virginia, p. ?g, t A view of South-Carolina, by John Drayton, p. 48. METHOD OF WORKING GOLD ORES. 155 cording to the following table, wiiich expresses the quan- tities of gold obtained from the quintal of the several earths. Ounces. Gross. Grains. Rotted manure (terreau) 0 1 56 Earth of uncultivated ground ~) 0 2 „fi (terre de Bruyere,) \ Garden mould 0 5 0 Mould of a kitchen garden 1 manured with dung yearly > 2 3 40 for sixty years J These results were at first contested; but at present it appears to be generally agreed that gold is obtained, but in a less quantity. Mr. Berthollet obtained forty grains and eight twenty-fifths of gold in the quintal of ashes. Messi-s. Rouelle, Darcet, and Deyeux likewise obtain- ed it. It is therefore a physical fact, that gold exists in vege - tables. The method of working the ores of gold is nearly the same as that used with silver ores. When the gold is in a native state, nothing more is required than to divide the ore by the pounding mill, and afterwards to wash and amalgamate it. If the ore be mineralized, it is torrefied, pounded, washed, fused with lead, and afterwards cupel- led. Eliquation is likewise used for poor ores. Those persons who explore the gold in small plates dis- seminated in the sand of certain rivers, are known in France by the name of Orpailleurs, or Pailloteurs, The pailloteurs of the river Uze, after having ascertained that the earth is sufficiently rich to be wrought, place a table of several feet in length, and about a foot and a half in width, on the banks of the river with ledges round three of its sides. Pieces of stuff with a long nap are nailed on to this board; and the sand is thrown upon it, and washed, to carry away the lighter particles. When the stuff is sufficiently charged with the small particles of gold, it is shaken into a vessel, agitated with water to carrv oft' the lightest sand, and afterwards amalgamated 156 METHOD OF WORKING GOLD ORES. with mercury.* Mr. Ell has given us an ample account of the process used in working the gold ores in Spanish South America. A sufficient quanticy of water is pro- cured to wash them. A stream is me.de to carry off the earth, and every lighter substance. Negro slaves, dis- persed on the banks, throw in fresh earth ; while others, standing in the brook, work it about with their feet and hands. Care is taken to lay pieces of wood across 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 proposed to terminate it, the water is turned off; and then, in presence of the mas- ter, the workmen take up the sand with wooden vessels, in the form of shallow funnels, of one foot in diameter, at the bottom of which is an aperture of one inch in width. This dish is filled with sand ; and by a circular motion the lighter substances are caused to flow off, wiiile die heavier settle to the bottom. The platina is afterwards separated grain by grain, with the blade of a knife, upon a smooth board. The rest is amalgamated, first by working with the hands, and afterwards with a wooden pestle in mortars of guaiacum wood; after which the mer- cury is separated from the gold by fire. The Baron de Born has reduced the method of working all the ores of silver and gold to one single process. The account which he has,given of this process in his work, may be reduced to the following operations : 1. The mineral is pounded, divided, and sifted. 2. It is properly roasted. 3. It is mixed with muriate of soda, water, and mer- cury ; and agitation is used to facilitate the amalga- mation. 4. The mercury is expressed from the amalgam. * For a very full account of the treatment of auriferous sanrls,the following works may be consulted:—1. The Memoir of Mr. Reau- mur on the Auriferous Sands of France, printed among those of the Academy for the year 1718. 2. The Memoir of Mr.' Guettard on the Ariege, inserted in the volume for 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 last work, the various processes are discussed ; and this celebrated mineralogist proposes others more oeconomical and advantageous. ASSAY OF GOLD ORES. 157 5. The expressed mercury is exposed to distillation. 6. The silver is refined by the cupel. These operations were first executed at Schemnitz in Hungar)-, and afterwards at Joackimstal in Bohemia, in the presence of the greatest mineralogists in Europe, sent thither by the various sovereigns of Europe, The muriate of soda is used to decompose the sul- phates produced by the calcinations. To determine the fineness of gold with accuracy, the purest is supposed to be twenty-four carats, and these ca- rats are divided into thirty-second parts; the carat is al- ways represented by a grain poids de marc. The law directs the operations to be performed upon twenty-four grains of gold, tolerates twelve, and prohibits six, on account of the difficulty of appreciating the divi- sion iuJi result from these small quantities. In the parting assay, very pure silver must be made use of. This is mixed with the gold in the proportion of four to one, which has occasioned the name of Quarta- tion to be given to the process. Mr. Sage has found that two parts and a half of silver to one of gold form the mixture most proper for making the cornet of assay. 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 result of the cupel- lation is a button containing fine gold and fine silver. This is flattened, lamellated, and rolled up into a spiral; put into a small matrass, and six gross or drams of pure ni- tric acid, at thirty-two degrees of concentration, are pour- ed on it. As soon as the matrass is heated, the metal becomes brown, the silver is dissolved, and much red va- pours are disengaged. At the end of fifteen minutes the solution is decanted; and an ounce of very pure acid, ra- ther more concentrated, is poured on, to carry away the last portions of silver. This solution is decanted, after a digestion of fifteen or twenty minutes; at which period warm water is added, and the cornet is washed until the water comes off tasteless. It is then dried in a crucible, weighed, and the fineness judged by the diminution of its weight. Schindlers and Schutler have maintained that gold al- ways retains a small quantity of silver, wiiich they have 158 NITROUS SOLUTION OF GOLD. called die Interhalt, or Surplus. • Mr. Sage found a six- ty-fourth part of a grain in the best conducted assay. In order to separate the silver which is dissolved in the nitric acid, diis solution is diluted A\ith a considerable quantity of water, and flat pieces of copper are piunged in it; which precipitate the silver, as we have observed in treatine of the solution of silver. Gold, exposed to fire, becomes red-hot before it melts. When melted it suffers no alteration*. Kunckel and Boyle kept it in a glass-house furnace for several montlis without change. Homberg has nevertheless observed that this metal, ex- posed to the focus of the lens of Tschirnaus, smoked, was volatilized, and even vitrified in part. Mr. Macquer has verified this observation by the mirror of Mr. De Trudaine; he observed the gold fume, become volatilized, and covered with a dull pellicle, which constituted a vio- let-coloured oxide towards the middle. Gold is not attracted by the sulphuric acid. The nitric acid appears to have a real action upon it. Brandt is the first who announced the solution of gold by this acid. The experiments were made in the presence of the King of Sweden, and verified by his Academy. Messrs. Scheffer and Bergmann have confirmed the asser- tion of Brandt; and Mr. Sage afterwards published a se- ries of experiments on this subject. I am convinced, from my own experiments, several times repeated, that the purest nitric acid attacked gold in the cold, and dis- solved a sixty-fourth part of a grain. When very pure ni- tric acid is boiled upon gold equally pure, the solution may be ascertained in three ways—1. By the diminution of the weight of the metal. 2. By evaporation of the acid; in which case a purple spot remains at the bottom of the evaporatory vessel. 3. By the parting operation, by means of a plate of silver put into the liquor. In this case black flocks are in a short time disengaged, which consist of the gold itself. These phenomena appear to announce a true solution; and not a simple division or suspension, as wras supposed. * Gold, when fused by a strong heat, is of a beautiful green 'co- Four during the fusion. FULMINATING COLS. 159 The quantity of gold dissolved appeared to me to vary according to the strength of the acid, the time of the ebul- lition, and die thickness of the metallic body. The nitro-muriatic acid, and the oxigenated muriatic acid, are the true solvents of gold. These acids attack it with greater energy in proportion as they are more con- centrated, and as the surface of the gold is larger. The solution may likewise be accelerated by heat. This solution has a yellow colour, is caustic, and tinges the skin of a purple colour. If it be properly concen- trated, it affords yellow crystals, resembling topazes, which affect the form of truncated octahedrons. These crystals are a true muriate of gold, according to Messrs. Berg- mann, Sage, &c. If the solution of gold be distilled, a red liquor is obtained, which consists of the muriatic acid, coloured by a small quantity of gold which it has carried over. This fluid was distinguished by the adepts under the name of Red Lion. Gold may be precipitated from its solution of several colours, according to the nature of the substances em- ployed to make the precipitation. Gold is precipitated by lime and magnesia in a yellow powder, in which the gold exists nearly in the metallic state ; a slight degree of heat only being necessary to convert it to that state. The alkalis likewise precipitate gold in the form of a yellowish powder; and the precipitate is soluble in the sulphuric, nitric, and muriatic acids. These concentrated solutions suffer the gold to precipitate ; crystals have not been obtained from them. If ammoniac be poured on a yellowish solution of gold, the colour disappears; but, at the end of a certain time] small flocks are disengaged, which become more and more yellow, and gradually subside to the bottom of the vessel. This precipitate, being dried in the shade, is known by the name of Fulminating Gold; a denomina- tion which it has obtained on account of its property of detonating, when gently heated. Ammoniac is absolutely necessary to produce this ef ■ feet. The experiments of several chemists have taught us__ 1. That, by gentiy heating fulminating gold in copper 160 FULMINATING GOLD. tubes, one extremity of which was plunged in the pneu- mato-chemical apparatus by the assistance of a svphon, alkaline gas is obtained, and the precipitate is deprived of its fulminating property : this fine experiment was made by Mr. Berthollet. 2. Bergmann has observed that, by ex- posing fulminating gold to a gentle heat, incapable of causing it to fulminate, it becomes deprived of diat pro- pertv. 3. When the gold is made to fulminate, in tubes whose extremities are inserted under a vessel filled with mercury, the product is nitrogene gas, and some drops of water. 4. By triturating fulminating gold with oily sub- . stances, it is deprived of its property of fulminating. From these established facts, it is evident that fulmi- nating gold is a mixture of ammoniac and oxide of gold. When this mixture is heated, the oxigene is disengaged at the same time with the hydrogene of the alkali. These two gases take fire by simple heat, detonate, and produce water; the nitrogene gas then remaining alone. From these principles it ought to follow, that oily substances which combine with the oxigene, acids which seize the alkali, or a gentle and long-continued heat, which volati- lizes the two principles without inflaming them, ought to deprive this preparation of its property of fulminating. The nitrous sulphur which Mr. Baume supposed to be formed, in his explanation of this phenomenon, does not exist; for the solution of the oxide of gold by the sul- phuric acid, "when precipitated by ammoniac, affords a fulminating precipitate. Gold is precipitated from its solution by several metals, such as lead, iron, silver, copper, bismuth, mercury, zinc, and tin. This last precipitates it instantly in the form of a powder, distinguished by the name of the Purple Pow- der of Cassius. This precipitate is much used in porce- lain manufactories. Some very good observations on this preparation may be seen in the Dictionary of Macquer. Gold may likewise be precipitated from its solution by ether: this liquor seizes the gold in a moment, and some- times instantly revivifies it. I have seen the gold form a stratum at the surface of the liquor, and the two fluids no longer contained a particle. The sulphures of alkali dissolve gold completely. No- thing more is necessary for this purpose, than quickly to HABITUDES AND USES OF GOLD. 161 fuse a mixture of equal parts of sulphur and potash with one-eighth of the total weight of the gold in leaves. This substance may then be poured out, pulverized, and dis- solved in hot water. The solution has a yellowish green colour. Stahl affirms that Moses dissolved the golden calf by a similar process ; and that, though the beverage must have been of a disagreeable taste, this circumstance was an additional reason for preferring the method, in order that the Israelites might longer retain their disgust for idolatry. Gold unites with most of the metals. Arsenic renders it brittle, as well as bismuth, nickel, and antimony. All these semi-metals render it white and eager. Gold unites very well with tin and' lead. These two metals deprive it of all its ductility, Iron forms a very hard alloy with gold, which may be employed to much greater advantage than pure gold. Copper renders it more fusible, and communicates a reddish colour to it. This alloy forms money, gold plate, and toys. Silver renders it very pale. This alloy forms the green gold of goldsmiths. Gold is employed for a variety of purposes. It is en- titled, by the first rank which it holds among metals, to the most noble uses. As its colour is agreeable to the eye, and is not subject to tarnish, it is used in ornaments, or as toys; for which purpose it is wrought into a thousand forms. For some purposes it is drawn into very fine wire, and used in embroidery. For other purposes it is extended into leaves so extremely thin, that the slightest breath of wind carries them away : in this form it is applied upon wooden articles by means of size. For other purposes it is reduced into a very fine pow- der, in which case it is called Ground Gold, Shell Gold, Gold in Rags, &c. The ground gold is prepared by levigating the clip- pings of gold leaf with honey, washing them with water, and drying them with the particles which subside. Vol. IT. X 162 CHARACTERS OF ALCHYMISTS. Shell gold consists of ground gold mixed with a muci laginous water. ' In order to make the gold in rags, pieces of linen are steeped in a solution of gold, afterwards dried, and then burned. When it is required to use them, a wet cork is dipped in wood ashes, and rubbed upon such articles of silver as are intended to be gilded. For some purposes it is amalgamated with mercury. This amalgam is applied upon copper, the surface being previously well cleared. It must be spread very even, and the mercury driven off by heat This forms the or moulu. A coating of gilders wax is laid over the gold thus ap- plied. This is made with red bole, verdigris, alum, and sulphate of iron, incorporated and fused with yellow wax. The piece is heated a second time, to burn off the wax. Gold was formerly used in medicine. This remedy was much in fashion in the fifteenth century. Its good- ness has at all times been proportioned to the dearness of the drug. Bernard de Palissy exclaimed strongly against the apothecaries of his time, who demanded ducat gold from the sick to put into their medicines, under the pretence that the purer the gold the more speedy would l^e the restoration of the health of the patient. As this metal is highly valued, the rage of forming it constituted a known sect, under the name of Alchymists, which may be divided into two classes. The one very ignorant, frequently unprincipled, and most commonly uniting both qualities, suffered themselves to be imposed on by certain phenomena, such as the increase of weight of metals by calcination, the precipitation of one metal by another, and the yellow colour which some bodies, and certain preparations affect. They grounded their notions on certain vague principles concerning the formation of bodies, their common origin, their seeds, &c. It is this sect which has caused alchymy to be defined, ars sine arte, cujus principium est mentiri, medium la- borare, tertium mendicare. These alchymists, after hav- ing been themselves the dupes for a considerable time, al- ways endeavoured to impose on others ; and there are a thousand trieks and impositions related of this class of men, which deserves only to be despised and pitied. CHARACTERS OF ALCHYMISTS. 163 There is another class of alchymists which do not de- serve to be made the object of public derision and con- tempt. This is formed of celebrated men, who, ground- ing their ideas on the received principles, have directed their researches towards tLis object. This class of men is valuable on account of their genius, probity, and con- duct. They have formed a language, held scarcely any communication but with each other, and have at all times distinguished themselves by their austere manners, and their submission to Providence. The celebrated Becher is a name which alone suffices to render this sect respect- able. The following passage, extracted from Becher, ex- hibits an idea of their language, and manner of proceed- ing in this study. " Fac ergo ex luna et sole mercurios, quos cum primo ente sulphuris prascipita, przeeipitatum philosophorum igne attenua exalta, et cum sale boracis philosophorum li- quefac et fige donee sine fumo fluat. Qua?, licet brevi- ter dicta sint, longo tamen labore acquiruntur et itinere, ex arenoso namque terrestri Arabico mari, in mare rubrum aqueum, et ex hoc in bituminosum ardens mare mortu- um itinerandum est, non sine scopulorum et voraginum periculo, nos, Deo sintlaudes, jam appulimus ad portum." Becher, Phys. Sub. i. s. v. cap. iii. page 461. in 8vo. And elsewhere, " Concludo enim, pro thesi firmissima, asinus est qui contra alchymiam loquitur, sed stultus et nebulo qui illam practice venalem exponit." The enlightened alchymists have enriched chemistry With most of the products which wrere known before die late revolution. Their knowledge and their inde- fatigable ardour put them in the situation of pro- fiting by all the interesting facts which offered them- selves. God forbid that I should induce any person to enter into this path. I would use every effort to prevent any one from engaging in this research, so full of disappoint- ment, and so dangerous to attach the mind to it. But I am of opinion that the alchymists have been too lightly treated; and that this sect, which on many accounts is worthy of commendation, has not received the esteem and gratitude it is entitled to. 164 OF PLATINA. In addition to these reasons, I must observe that die-. mical phenomena become so wonderful; the torch of analysis has enlightened us to such an extent: we now decompose and reproduce so many substances, which ten years ago were considered with equal probability as indecomposable as gold is now thought to be; that no chemist can take upon him to affirm that we may not arrive at the art of imitating nature in the formation of metals. CHAPTER XV. Concerning Platina. E were unacquainted with platina until the year 1748. It is to Don Antonio Ulloa, who ac- companied the French Academicians in their famous voyage to Peru, to determine the figure of the earth, that we are indebted for our first notions of tiiis metal. Charles Wood, who had himself brought this metal from Jamaica, made experiments upon it, which are related in the Philosophical Transactions for the year 1749 and 1750. Since that time, all the chemists in Europe procured this metal. Messrs. Scheffer in Sweden, Lewis in Eng- land, Margraff in Prussia, Macquer, Baume, De Buffon, De Milly, De Lisle, De Morveau, have successively made researches on this substance ; and we are indebted for great part of our present knowledge of this metal to the Baron de Sickengen. Platina has hitherto been found only in the metallic state. Its form is that of small grains or flattened plates, of a livid white colour, intermediate between that of silver and iron : it is from this colour that it derived its name of Platina, or Little Silver. If the grains of platina be care- w PURIFICATION, &C OF PLATINA. 165 fully examined, it is found that some of them are round- ed, and others angular. It has been found among the auriferous sands of South America, near the mountains of the districts of Novita and Cytara. These two metals are almost constantly ac- companied by a ferruginous sand obedient to the magnet. The platina of commerce usually contains a siriall quantity of mercury, arising from the amalgamation wiiich the ore has undergone in extracting the gold. When it is re- required to have platina in a very pure state, it must be exposed to heat, to drive off the mercury; and the magneti- cal parts, and the iron, must be sorted out with the magnet. Platina itself is slightly attracted by the magnet. M. L. affirms, in a Memoir read to the Academy of Sciences at Paris in the year 1785, that the lighter pieces of platina only are attracted by the magnet, and that they cease to be acted on wiien they exceed a certain size. The largest piece of platina which has been seen, is of the size of a pigeon's egg. It must be in the possession of the Royal Society at Bisca. M. L. affirms that platina is malleable in its natural state; and he passed it through the flatting mill in the presence of Messrs. Tillet and Darcet. Platina undergoes no alteration by exposure to the air; and fire alone does not even appear to possess the power of changing it. Messrs. Macquer and Baume kept it seve- ral days in a glass-house furnace, without its grains hav- ing suffered any other change than that they were slightly agglutinated. It has nevertheless been ascertained that heat, kept up for a long time tarnishes its surface, and increases its wreight. Margraff formerly made this ob- servation. Platina, exposed to the focus of the burning mirror of Mr. De Trudaine, fumes and melts. This metal may be hammered like gold and silver. It may likewise be fused upon charcoal, by the assistance of oxigenous gas. This substance resists the action of the acids, such as the sulphuric, the nitric, and the muriatic acids; it is soluble only in the oxigenated muriatic and the nitro-muriatic acids. One pound of the latter, digested on an ounce of platina, first assumes a yellow colour, then an orange colour, and lastly a very obscure brown. This solution 166 METHODS OF FUSING PLATINA. tinges animal substances brown; it spontaneously depo- sites small irregular fawn coloured crystals: but if it be concentrated, larger crystals are obtained, sometimes of an octahedral form,- as Bergmann has observed. The muriate of platina is scarcely caustic, though sharp; it fuses in the fire, gives out its acid, and leaves an obscure grey oxide. The sulphuric acid, poured on this solution, forms a precipitate of a dark colour; the precipitate occasioned by die muriatic acid, is yellowish. The alkalis precipitate platina from its solution; but, if it be gradually precipitated by potash, the precipitate is dissolved by the alkali in proportion as it is formed. A solution of the muriate of ammoniac, poured into a solut'o?! of platina, forms an orange-coloured precipitate, which is a true saline substance, totally soluble in water. This precipitate has been fused by Mr. De Lisle in a common fire (of a furnace). The result of the fusion is platina, still altered by some portion of saline matter; for it does not acquire ductility but by exposure to a much stronger heat. The property which the muriate of ammoniac possesses of precipitating platina, affords a very simple method of ascertaining the mixture of this metal with gold : so that the fear of this alloy, which had alarmed the Spanish mi- nistry so much as to occasion them to forbid its being wrought, does not at present exist, as we possess a sim- ple method of ascertaining the fraud : and it is much to be wished that this very precious metal should be restored to the arts, to which it cannot but be very useful, by its brilliancy, its hardness, and its unchangeable nature. The process of Mr. De Lisle to fuse platina, was pub- lished in 1774. Mr. Achard published a simpler method, nearly at the same time : it consists in taking two gross ' of platina, two gross of the white oxide of arsenic, two gross of the acidulous tartrite of potash, and putting them into a crucible well luted. This is to be exposed for an hour to a violent fire, which fuses the platina; but it is brittle, and whiter than ordinary platina. It is then to be exposed to a considerable heat under a muffle; by which means all the arsenic wiiich was combined with the platina is dissipated, and this metal left in a state of pu- METHODS OF FUSING PLATINA. 167 rity. Vessels of platina may be formed, by filling clay moulds with the alloy of platina and arsenic; and expos- ing the mould in the muffle, to dissipate the semi-metal. Mr. De Morveau substituted the arseniate of potash to advantage, instead of arsenic ; and he had already fused platina with his vitreous flux, made of pounded glass, bo- rax, and charcoal. Mr. Pelletier fused platina, by mixing it with phospho- ric glass and charcoal. The phosphorus then unites with the platina; and the phosphure of platina is exposed to a degree of heat sufficient to volatilize the phosphorus. Mr. Baum6 advises to fuse platina with a slight addition of lead, bismuth, antimony, or arsenic; and to keep the alloy in the fire a long time, to dissipate the metals wiiich have facilitated the fusion., Platina may likewise be fused with a metal soluble in an acid: the mixture being pulverized, the alloyed metol may be dissolved; and the powder of platina may then be fused with the flux of De Morveau. Instead of using a soluble metal, a calcinable metal may be employed, and treated as before.* '* " Jeannety of Paris has succeeded in working platina into wire, plates, and vessels of different kinds, adapted chiefly to chemical purposes. The following account of his process was given in a re- port by Pelletier.* " The crude platina is triturated with water, to remove any par- ticles of iron, or other impurities mixed with it. One pound and a half of it are mixed with three pounds of white arsenic, and one pound of purified potash ; a crucible capable of containing 20 pounds is placed in a furnace, so as to be well heated; and a third part of the above mixture is thrown into it; after applying to this a strong heat, a second portion is thrown in, and afterwards the re- maining part, care being taken to mix the whole by stirring with a rod of platina. The heat is raised, and when the whole is tho- roughly melted, the crucible is withdrawn, and allowed to cool. The metallic mass thus obtained is magnetic: it is broken and melted a second time in the same manner: and if this second fusion does not free it sufficiently from iron, it is fused a third time, though in general two fusions are sufficient. The first stage of the operation being finished, crucibles are taken, the bottoms of which are flat, and the circumference such as to give a mass of metal three inches and a quarter in diameter : they are raised to a red heat, and into each is thrown a pound and a half of the metallic substance obtained in the former part of the process, with an equal weight of arsenic, and * Mtmoire de Chimie, torn. ii. p. 138, 168 METHODS OF FUSING PLATINA. The cubic foot of crude platina weighs 1092 livres 1 ounce 7 gross 17 grains ; platina purified and fused weighs 1365 livres; and purified platina forged weighs 1423, 8, 7, 64. half a pound of potash: the heat is raised so as to melt this com- pletely : the crucible is then withdrawn, and allowed to cool, placing it horizontally, so that the bar of metal shall be of equal thickness. The bars thus obtained are placed in a furnace under a muffle, which ought not to be higher than the circumference of the bars placed on edge, and inclined a little towards the sides of the muffle; three bars are placed on each side of it; the fire is raised until the muffle be equally healed through its circumference ; and whenever the metallic bars begin to exhale vapour, the doors of the furnace are closed to preserve the heat at the same degree, it being necessary that it should be kept so to the end, as, if suddenly raised high, the whole operation would be defeated. The bar's are exposed to this heat for six hours, their places being changed occasionally, that they may be heated as equally as possible. They are then put into com- mon oil, and are exposed for the same length of time to a heat suf- ficient to dissipate the oil in vapour. This operation is continued as long as any vapour arises from the bar, and when this has ceased^ the heat is pushed as far as it can by the medium of the oil,—a step of the process without which the platina is not obtained perfectly malleable Lastly, when these operations have been finished, which, when they have been properly executed, require about ei^ht days, the bars are cleansed with nitrous acid, and are boiled in distilled water, to remove any adhering acid : they are then placed one above another, and exposed to the strongest possible heat, and beat, the heat being at first applied to them in a crucible, that no foreign matter may be introduced into the spongy substance of the bars. They are lastly heated in the naked fire, and formed into a square bar, which is hammered for a longer or shorter time according to its size. " A process given by Moussin Poyshkin, appears more easy of execution than that of Jeannety, and 'will probably afford the platina equally pure. The precipitate of platina from nitro-muriatic acid is to be washed with cold water, and reduced, by exposure to heat in a crucible, to the spongy metallic substance, which is usually ob- tained by this operation. This is to be washed two or three times with boiling water, to carry off any adhering saline matter. It is then to be boiled for half an hour in so much water mixed with one- tenth of muriatic acid, as will cover the mass to the depth of about half an inch in a glass-vessel; this removing am quantity of iron that might exist in the metal. This liquid is to be poured off, the pla- tina edulcorated and ignited To one part of this metal, two parts of quicksilver are to be added, and they are to be amalgamated in a glass or porphyry mortar; mixing them in small quantities at a time, as two drachms of mercury to three of platina, and adding to * this amalgam alternately smail quantities of platina and mercury, until the whole quantities are combined. In this way, and with pla- ALLOYS OF PLATINA. 169 Most of the neutral salts have no perceptible action upon platina. The results of several curious experiments may be seen in the Memoirs of Margraff. " \ The nitrate of potash alters platina, according to the experiments of Lewis and Margraff. Dr. Lewis, by heating a mixture of one part of platina and two parts of this nitrate, during three times twenty-four hours ob- served that the metal assumed a rusty colour, by dittus- ine the mixture in water, the alkali was dissolved; and the platina, deprived of all the soluble matter, is dimin- ished one-third. The powder taken up by the alkali is the oxide of iron, mixed with the oxide of platina. These experiments, as likewise the property which pla- tina possesses of being acted on by the magnet, prove that it contains iron; and Mr. De Buffon has concluded that this metal is a natural alloy of gold and iron. But it has been objected that the artificial alloy of these two me- tals, made in every possible proportion, never resembles platina; that this metal departs more from the properties tina in this state, the amalgamation is easily effected. When the amalgam has been completed, it must be quickly moulded in bars qr plates, of at least half an inch in thickness, and of such a length as to allow of their being easily managed in the fire. Half an hour after these have been formed, they begin to harden by the ox- idizement of the quicksilver. As soon as they have acquired the proper decree of hardness to be handled without breaking, which commonly takes place in a little more than an hour, they are to be placed in a furnace, and kept ignited under a muffle. The quick- silver is thus expelled, and the platina remains perfectly solid, so that after being strongly ignited two or three times before the bel- lows, it may be forged or laminated in the same manner as gold or silver.* " A very simpje process has also been lately given by Mr. Til- loch. It consists in exposing the precipitate from the solution of platina in nitro-muriatic acid, by muriate of ammonia, to such a de- gree of heat as will volatilize the saline matter, and inclosing it af- ter this in a piece of platina already malleable, and which has been spread out by the flatting mill. The envelope is then exposed to a sufficient temperature, and, while hot, is cautiously hammered. This is repeated until the whole is obtained in a compact state.f" • Nicholson's Journal, vol. ix. p. 65. t Philosophical Magazine, val. xxi. p. 17S. Vol. II. Y 170 ALLOYS OF PLATINA. of gold in proportion as it is deprived of iron : so that it is considered as a truly peculiar metal. This metal is capable of being alloyed with most of the known metals. Scheffer first affirmed that arsenic rendered it fusible. Messrs. Achard and De Morvcvm have availed them- selves of this property to fuse it, and compose vessels. Platina easily unites with bismuth. The result is ea- ger, verv brittle, difficultly cupelled; and the result is a mass which has little ductility. A.itimonv likewise facilitates the fusion of platina. The alloy is brittle ;* part of the antimony may be disengaged by fire ; but a sufficient quantity remains in combination to deprive the platina of its weight and ductility. Zinc renders this metal more fusible. The alloy is very hard; great part of the zinc may be volatilized by fire ; but the platina' always retains a small quantity. This metal unites easily with tin. This alloy is very fusible, and flows clear; it is eager, and very brittle : but when the tin is in a large proportion, the alloy is ductile; its grain is coarse, and it becomes yellow by exposure to the air. Lead unites very well with platina. A stronger heat is required to fuse this than the foregoing alloy. It is not ductile ; is no longer capable of being absorbed by the cu- pel, the absorption only taking place when the lead is in excess ; but the platina remains always united to a consi- derable portion of the metal. Nevertheless Messrs. Mac- quer and Baume cupelled one ounce of platina and twenty ounces of lead, by exposing this alloy, for fifty hours, in the hottest part of the porcelain furnace at Seves. Mr. De Morveau had the same result in Mr. Macquer's wind- furnace : the operation lasted between eleven and twelve hours. Mr. Baume observed that the platina obtained by this process possesses the power of being forged, and sol- dered completely, without the assistance of any other me- tal, which renders it a most valuable acquisition in the arts. Dr. Lewis could not unite forged iron with platina; but having melted crude iron with this metal, there re- sulted an alloy so hard that the file could not touch it; it was ductile in the cold, but broke short when hot. ALLOYS OF PLATINA. 171 Copper and platina alloyed together form a very hard metal, which is ductile, while the copper predominates in the proportion of three or four to one : it takes a fine po- lish, and was not tarnished during the space of ten years. Platina, alloyed with silver, deprives it of its ductility, increases its hardness, and tarnishes its colour. These two metals may be separated by fusion and repose. Lewis observed that the silver which is fused with platina is thrown up against the sides of the crucible with a kind of explosion : this phenomenon appears to be owing to the silver, as Mr. Darcet found it break porcelain balls in which it was inclosed, and out of wiiich it was projected by the action of the fire. Gold is not capable of being alloyed with platina but by the most violent heat: the colour of the gold is prodigi- ously altered, and the alloy possesses considerable ducti- lity." We know enough of the properties of this metal to presume that it will prove of the greatest use in the arts. Its almost absolute infusibility, and its unchangeableness, render it of extreme value to form chemical vessels, sucji as crucibles, and the like. The property of soldering or welding without mixture, renders it preferable to gold or silver. Its density and opacity render it likewise of great value for the construction of optical instruments; and the abbe Rochon has constructed a mirror whose effect greatly surpasses that of the mirrors before made of steel and other metals. This metal unites two qualities never before found in one and the same substance. Like other metallic mirrors, it reflects but one single image; at the same time that it is as unchangeable as the mirrors of glass. 172 TUNGSTEN AND WOLFRAM. CHAPTER XVI. Concerning Tungsten and Wolfram. E are acquainted witii two minerals which may be distinguished by the generic title of Tungsten: the one white, and known by the name of Tungsten, or the Heavy Stone of the Swedes; the other known by the name of Wolfram by mineralogists. We shall examine each separately. ARTICLE I. Concerning Tungsten. Tungsten is a substance of an opaque white colour, very « heavy, and of a moderate degree of hardness :^ its crys- tals are octahedrons. Its specific gravity is 6,0665, ac- cording to Brisson; from 4,99 to 5,8, according to Kirwan. The cubic foot weighs 424 livres 10 ounces 3 gross 60 grains. When exposed without addition to the flame of the blow-pipe, it decrepitates without melting. With soda it is divided with a slight effervescence ; is partly solu- ble in the native phosphate, or microcosmic salt; and affords a fine blue colour without the least appearance of red in the refracted light, as happens with cobalt. It is soluble in borax without effervescence. Bergmann affirms that by pouring the muriatic acid upon pulverized tungsten the powder immediately assumes a fine bright yellow colour. To this character Scheele adds that of becoming blueish when boiled in the sulphu- ric acid. w ACID OF TUNGSTEN. 173 This substance has a sparry appearance, and was long confounded with the white tin ore. It is found at Bitsberg, at Riddharhittan, at Marienburg, at Al- temburg in Saxony, and at Saubergnear Ehrenfrieders- dorff. Mr. Raspe, in Crell's Annals for June 1785, gave an account of two mines of tungsten in the province of Cornwall, from which thousands of tons might be ex- tracted. This philosopher obtained the metal in the pro- portion of about thirty-six livres the quintal. He adds that this metal contains little iron; that it is very fixed, and refractory in the fire; and that it acts on glass like the hardest steel. Cronstedt arranges the tungsten among iron ores; and defines it to be ferrum calciforme terrd qua Jam incog- jtitd intimd mixtum. Scheele has affirmed that it is a salt resulting from the combination of calcareous earth with a peculiar acid; which acid, combined with lime-water, regenerates tungsten. Bergmann considers the acid earth of tungsten as a me- tallic acid. Several processes are at present known for extracting the acid of tungsten. 1. Any desired quantity of this mineral is to be pul- verized, and fused with four times its weight of carbonate of potash, and poured out upon a plate of metal. The mass is then to be dissolved in twrelve parts of boil- ing water. A white powder separates during the solution, and falls to the bottom of the vessel. This precipitate is a true carbonate of lime, mixed with a small quantity of quartz, and a portion of undecomposed tungsten. The carbonate of lime may be taken up from the preci- pitate by nitric acid ; and the remaining - tungsten being mixed with the former proportion of carbonate of potash, is to be fused, dissolved, and by a repetition of these oper- ations will at length be totally decomposed. The wrater in which the fused masses were washed, holds in solution a salt formed by the tungstic acid and the :vlk:i'l made use of. If this solution be saturated with nmic acid, it seizes 174 ACID OF TUNGSTEN. the alkali; the solution becomes thick ; and a white pow- der falls down, which is the tungstic acid. 2. Scheele, the author of this first process, proposes a second, which consists in digesting three parts of weak nitric acid upon one of pulverized tungsten. This pow- der becomes yellow ; the fluid is then decanted, and two parts of ammoniac are poured upon the yellow powder. The powder then becomes white ; and in this way die re- peated actions of the acid and the alkali are applied until the tungsten is dissolved. Out of four scruples, treated by Scheele in this manner, there were three grains of insoluble matter, which was a true quartz. By adding the prussiate of potash to the nitric acid made use of, he obtained two grains of Prussian blue ; potash precipitated three of chalk ; and the ammoniac uniting to the nitric acid, precipitated an acid powder, which is the true tung- stic acid. In this experiment the nitric acid seizes the lime, and uncovers the tungstic acid, which is seized by the alkali. The muriatic acid may be substituted to advantage instead of the nitric acid, and even gives it a yellow colour. Scheele and Bergmann considered this acid powder as the true tungstic acid in a state of purity. Messrs. Delhuvars have asserted that this acid was mixed with the acid made use of in obtaining it, and also with the alkali; they assert that the yellow poyvder which is uncovered by the digestion of the nitric acid, is the true acid oxide of tungsten yvithout mixture. The white powder which is obtained by decom- posing the alkaline solution of tungsten by an acid, is acid to the taste, reddens the tincture of turn- sol, precipitates the sulphure of alk^di of a green colour, and is soluble in twenty parts of boiling water. ACID OF TUNGSTEN. 175 Properties of the white powdfr ob- Properties of the yellow matter tained bu decomposing the solu- obtained by fire or by acids. lion of the ore of tungsten by an acid. 1. An acid taste, reddening the 1. Insipid, reddening the tine- tincture of turnsol. ture of turnsol. - 2. f.xposed to flame urged by 2. Treated with the blow- the blow-pipe, it passes to a pipe, it preserves its yellow co- brown and black colour, without lour in the external flame ; but affording either fumes or signs swells up, and becomes black, of fusion. without fusing, in interior blue flame. 3. It is soluble in twenty parts 3. It is insoluble, but capable of boiling water. of becoming so divided as to pass through the filters. 4. It becomes yellow by boil- 4. The three mineral acids ins? in the nitric and muriatic have no action upon it. acids, and blueish in the sulphu- ric acid. From this comparison it appears that the acid is purer in the yellow powder than in the white; and the saline combinations of these two substances have confirmed Messrs. Delhuyars in their opinion. The yellow acid, combined with potash, either in the dry or humid way, forms a salt with excess of alkali. If a few drops of nitric acid be poured on this salt, a white precipitate is instantly formed, wiiich is re-dissolved by agitation. When all the alkali is saturated, the solution is bitter; if more acid be poured in, the precipitate which falls down is no longer soluble. This precipitate, when well edulcorated, is exactly of the same nature as the white poyvder w^e have spoken of. The experiments of Messrs. Delhuyars, and of Mr. De Morveau, prove very clearly that this white poyvder contains the acid of tung- sten, a portion of the potash yvith which it was'before combined, and a small quantity of the precipitating apid. It is therefore well proved that the yellow matter is the pure oxide, and the true tungstic acid. It is likewise very certain that this acid exists ready ibrmed in the me- tal ; and that its oxigene is afforded neither by the decom- posing :i of another acid, nor the fixation of the oxigenous gas of the atmosphere ; it appears to exist in the mineral, and to constitute a salt of many principles. The pure tungstic acid dissolves ammoniac; but the result is always with excess of alkali. This solution af- 176 PROPERTIES OF WOLFRAM fords by evaporation small crystals, of a penetrating bit- ter taste, soluble in water, and then reddening blue pa- per. The alkali is easily separated; and these crystals return by calcination to the state of yellow powder, en- tirely similar to that which entered into its composition. If the calcination be made in closed vessels, the residue is of a deep blue colour; for the yellow colour does not appear unless the calcination be made in the open air. The experiments of Mr. De Morveau permitted him to class the affinities of this acid in the folloyving order, which is the same as that of the arsenical acid, lime, ba. rytes, magnesia, potash, soda, ammoniac, alumine, me*. tallic substances. ARTICLE II. Concerning Wolfram. Wolfram is of a blackish brown colour, sometimes af- fecting the form of an hexahedral compressed prism, ter- minated in a dihedral summit. These surfaces are fre- quently striated longitudinally. Its fracture is lamellated, foliated, and the leaves are flat, though rather confused. Externally it resembles schorl; but is not fusible, and is incomparably heavier. Some mineralogists have taken it for an arsenical ore of tin; others for manganese, mixed with tin and iron. Messrs. Delhuyars, who made a strict analysis of it, found it to contain manganese 22, oxide 13|, quartzose powder 2, yelloyv po\yrder or tungstic acid 65. The yvolfram which was analyzed by these chemists, came from the tin mines of Zinnyvalde, on the frontiers of Saxony and Bohemia. Its specific gravity was 6,835. Wolfram does not melt by the blow-pipe without ad- dition, its angles being scarcely rounded. With the na- tive phosphate, or microcosmic salt, it melts with effer- vescence, and affords a glass of an hyacinth colour, It effervesces with borax, and forms a greenish yellow glass in the blue flame. This glass becomes red in the external flame. . ALLOYS OF WOLFRAM. 177 Pulverized yvolfram upon which the muriatic acid is boiled, assumes a yellow colour like tungsten. Messrs. Delhuyars' fused in a crucible two gross cf pulverized yvolfram, and four gross of potash. The fused mixture being poured out on a plate of copper, a black matter remained in the crucible ; yvhich, yvhen well edul- corated, yveighed thirty-seven grains, and yvas found to be a mixture of iron and manganese. The mass yvhich had been poured out yvas dissolved in water, filtered, and saturated with nitric acid. It afforded a wiiite precipitate, absolutely similar to that obtained from tungsten by a similar process. The process of Scheele, by the humid yvay, succeeds equally well, and even appeared to Messrs. Delhuyars to be more advantageous. They prefer the disengagement, by mere heat, of the ammoniac which holds the tungstic acid in solution. One hundred grains of wolfram, treated with the muriatic acid and ammoniac, afforded them six- ty-five grains of a yellow poyvder, yvhich is the pure acid. This yellow acid powder unites with most of die me- tals. Messrs. Delhuyars relate the following facts : 1. One hundred grains of gold leaf, and fifty grains of the yellow matter, urged by a violent heat for three quar- ters 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 yveighed one hundred and thirty-nine grains, and yvas cupelled yvith lead, though with difficulty. 2. Similar proportions of platina and the yellow matter, treated in the same yvay (for an hour and a quarter,) af- forded a friable button, in yvhich grains of platina yvere distinguishable, of a yvhiter colour than ordinary. It yveighed one hundred and forty grains. 3. With silver, the yellow matter formed a button of a white givyish colour, rather spongy, yvhich extended it- self easily by a few strokes of the hammer ; but on con- tinuing them it split in pieces. This button weighed one hundred and forty-two grains, and the mixture was per- fect. Vol. II. Z 178 ALLOYS OF WOLFRAM. 4. With copper, it afforded a button of a coppery red colour, inclining to grey, yvhich yvas spongy, and consi- derably ductile. It weighed one hundred and thirty-three grains. 5. With crude or cast iron, of a yvhite quality, it af- forded a perfect button, yvhose fracture yvas compact, and of a greyish white colour. It was hard, brittle, and weighed one hundred and thirty-seven grains. 6. With lead, it afforded a button of an obscure grey colour, with very little brilliancy, spongy, very ductile, and splitting into leaves yvhen hammered. It weighed one hundred and twenty-seven grains. 7. The button formed with tin yvas of a lighter grey than the preceding, very spongy, someyvhat ductile, and weigh- ed one hundred and thirty-eight grains. 8. The button of antimony was of a bright grey, ra- ther spongy, brittle, and easily broken; it yveighed one hundred and eight grains. 9. That of bismuth presented a fracture yvhich, when seen in one direction, yvas of a grey colour, and metallic lustre ; but in another direction it appeared like an earrh yvithout any lustre: but in both cases an infinity of pores yvere seen over the yvhole mass. It yveightd sixty-eight grains. 10. The button formed with zinc yvas of a black greyish colour, and an earthy aspect, very spongy, and brittle: it yveighed forty-two grains. 11. With common manganese it afforded a button of a blueish grey colour, and earthy aspect. Its internal part, examined yvith a lens, resembled an impure scoria of iron; it weighed one hundred and seven grains.* These experiments confirm the suspicion of the cele- brated Bergmann; yvho, from the specific gravity of this substance, and its property of colouring the native phos- phate and borate of soda, concluded that it was of a metallic nature. * In Cullen's Translation of the Chemical Analysis of Wolfram, printed in London in 1785, I find the word brown in everyplace where M. Chaptal has used the word grise, or grey. Not having the original, 1 cannot speak with certainty ; but from circumstances conclude this last to be right. T. PROPERTIES OF WOLFRAM OXIDE. 17& The change of colour which accompanies its reduction, its increase of yveight by calcination, its metallic aspect, and its uniting with other metals, are incontestable proofs of its metallic nature. The yelloyv matter must therefore be considered as a metallic oxide; and the button obtained by exposing tins oxide to a strong fire, with powder of charcoal, is a true metal. Messrs. Delhuyars having put one hundred grains of the vellow matter into a lined crucible wrell closed, and exposed it to a strong heat for an hour and a half, found upon breaking the crucible, yvhen cold, a button yvhich yvas reduced to powder between the fingers : its colour was grey. On examining it with the magnifier, an as- semblage of metallic globules were seen, among which some were of the bigness of a pin's head, and when broken exhibited a metallic fracture resembling steel. It yveighed sixty grains, and of course there was a diminu- tion of forty. Its specific gravity was 17,6. Having calcined a part of it, it became yelloyv yvith TVo increase of weight. The nitric and the nitro-muriatic acid changed it into a yellow powder. The sulphuric and muriatic acids diminislied its yveight, and their solution let fall Prussian blue. The metallic grains always remained af- ter the action of these acids. This metal shews various properties, which distinguish it from all others known. 1. Its specific grayity is 17,6. 2, It forms peculiar glass yvith the several fluxes. 3. It is almost absolutely infusible, much less fusible than manganese. 4. Its oxide is of a yellow colour. 5. It forms peculiar alloys with the known metals. 6. It is insoluble in the sulphuric, muriatic, nitric, and nitro-muriatic acids; and these two last convert it into an oxide. 7. The oxide combines with alkalis. 3. The oxide is insoluble in the sulphuric, nitric and muri- atic acids, and assumes a blue colour with this last. Wolfram ought to be considered as an ore, in yvhich this metal is combined yvith iron and manganese, as Messrs. Delhuyars have proved. 180 MOLYBDENA. CHAPTER XVII. Concerning Molybdena. TWO substances have long been confounded toge- ther under the name of Black Lead Ore, Mineral Lead, Plumbago, and Molybdena, yvhich the more ac- curate analysis of the celebrated Scheele has proved to be of a very different nature. Molybdena cannot be confounded yvith the mineral of yvhich black lead pencils are made, yvhich is called Plum- bago. The characteristic differences are sufficiently evi- dent to leave no doubt on this subject. Molybdena is composed of scaly particles, either large or small, and slightly adherent to each other. It is soft and fat to the touch, soils the fingers, and makes a trace of an ash-grey colour. Its aspect is blueish, nearly re- sembling that of lead. The mark it makes on paper has an argentine brilliancy; whereas those of plumbago are of a darker and less shining colour : its poyvder is blueish; by calcination it emits a smell of sulphur, and leaves a whitish earth. The nitric and the arsenical acids are the only acids yvhich attack it effectually; it is soluble in soda with effervescence before the bloyv-pipe; it causes the ni- trate of potash to detonate, and leaves a reddish residue; when exposed to the flame of the blow-pipe in the spoon, it emits a yvhite fume. Plumbago is less fat, less granulated, and composed of small brilliant particles. It loses in the fire -&8ff of its yveight, and the residue is an oxide of iron. Molybdena has been found in Iceland, in Sweden, in Saxony, in Spain, in France, &c. that of Iceland is found in plates, in a red feld spar mixed yvith quartz. Mr. Hassenfratz gave Mr. Pelletier samples of molyb- dena similar to those of Iceland, yvhich he had collected in the mine named Grande Montagne de Chateau Lam- bert, near Tillot, yvhere a copper mine yvas formerly wrought. MOLYBDENA AND ITS OXIDE. 181 William Bowies appears to have found molybdena near the village of Real de Monasterio: it is in banks of grit stone, sometimes mixed with granite. The molybdena of Nordberg in Sweden is accompa- nied yvith iron that obeys the magnet. The molybdena of Altemberg in Saxony nearly resem- bles that of Nordberg.* Mr. Peiictier analyzed all these species ; and his work may be consulted in the Journal de Physique for 1785 ; but the experiments we shall here relate yvere made with that of Altemberg. Molybdena, exposed to heat on a test, becomes co- vered, after the space of an hour, yvith a yvhite oxide; which, when collected by a process similar to that used with the sublimed oxide of antimony, has all the appear- ances of this last substance. The whole of the molyb- dena may by this means be converted into oxide. We are indebted to Mr. Pelletier for this fine experiment, yvhich had escaped Scheele. Molybdena is indestructible in close vessels, and pro- digiously refractory, according to the experiment of Mr. Pelletier, made with balls of porcelain exposed to the most intense heat. Molybdena treated yvith the black flux yvas not reduced, nor even deprived of its sulphur. Molybdena fused yvith iron affords a button, yvhich re- sembles cobalt: it unites likewise perfectly yvith copper; but yvhen mixed yvith lead and tin, it renders them so re- fractory that the results are pulverulent and infusible al- loys. The oxide of molybdena obtained by calcination, or by the action of the niuic acid, is not reducible yvhen treated yvith black flux, alkali, charcoal, or the other saline flux- es ; nevertheless if the oxide of lead or copper be added, the metals yvhich result are alloyed with a portion of mo- lybdena, yvhich may be separated. * Molybdena is found in Chester county, Pennsylvania, mixed with iron and, copper pyrites, and adhering to white quartz. Its specific gravity at 62° of Fahrenheit, is 4.648. It has also been discovered on granite, in the southern parts of the state of New- York.— Am. Ed. 182 MOLYBDENA AND ITS OXIDE. The oxide of molybdena made into a paste with oil, dried by the fire, put into a lined crucible, and urged by a violent heat for two hours, afforded Mr. Pelletier a subr stance siightiy agglutinated, which could be broken with the fingers. * It was black, but perceptibly of a metallic aspect. When viewed yvith the magnifier, small round grains of a greyish metallic colour were seen, yvhich are the metal of molybdena. It is prodigiously refractory: for the fire yvhich Mr. Pelletier gave was stronger than that yvhich Mr. Darcet used in the same forge to fuse platina and manganese. 1. Molybdena is calcinable, and passes to the state of a very white oxide. 2. It detonates with nitre, and the residue is an oxide of manganese mixed yvith alkali. 3, The nitric acid converts it into a white acid oxide. 4. The alkalis disengage hydrogenous gas from it in the dry way, and the residue is the oxide of manganese and al, kali. 5. It alloys yvith the metals in different manners. Its alloys yvith iron, copper, and silver, are very friable. 6. When treated with sulphur, it regenerates the mineral molybdena. According to Mr. Kirwan, the mineral of molybdena contains fifty-five pounds sulphur, and forty-five metal. The iron is accidental. To reduce the mineral molybdena to powder, Scheele directs that it be triturated in a mortar with a small quan- tity of sulphate of potash. The powder is afterwards washed in hot water, to carry off the salt, and the mo- lybdena remains pure. This ore is a true pyrites, which, when treated with the blowr-pipe, emits a white acid fume. But as this me- thod affords only a small quantity of oxide, another me- thod is used to obtain it. Thirty parts of nitric acid are distilled on one of powder of molybdena; care being taken to use a large retort, and to pour the acid on at seve- ral times, having previously diluted it with one-fourth of water. The receiver being luted on, the distillation is performed on the sand-bath. When the fluid begins to feoil, a considerable quantity of nitrous gas comes over. ACID OF MOLYBDENA. 183 The distillation being continued to dryness, there remains a powder, upon which an additional dose of nitric acid is poured; and this management is repeated until all the m- trkacid has been used. At the end of the process there remains a residue as white as chalk, which is to be wash- ed with water to carry off a small quantity of sulphuric acid, which is formed by the decomposition of the nitric acid upon the sulphur. After this edulcoration there re- mains six gross thirty-six grains of an acid powder, when the operation has been made with thirty ounces of nitric acid, and one ounce of molybdena. It is the molybdic acid. The arsenical acid distilled from the mineral molybdena, likewise affords the molybdic acid. It is evidendy seen that its formation, like that of the arsenical acid, is owing only to the decomposition of the acid made use of, and the fixation of their oxigene on the metal employed. This acid is white, and leaves a perceptibly acid and metallic taste on the tongue. Its specific 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 rise m sublimation, but by the assistance of the air. It colours the native phosphate of a beautiful green. If it be distilled yvith three parts of sulphur, the mine- ral molybdena is regenerated. This acid is soluble in five hundred and seventy times its weight of yvater at a mean temperature. The solution is very acid; decom- poses the solutions of soap; precipitates the sulphures of alkali. It becomes blue and consistent by cold. The concentrated sulphuric acid dissolves a large quan- tity of it. The solution assumes a fine blue colour, and becomes thick by cooling. This colour disappears by hent, and returns again as the fluid cools. The muriatic acid dissolves a considerable quantity by the assistance of ebullition. If the solution be distilled, it leaves a residue of an obscure blue colour. By an in- crease of heat, yvhite sublim.ite rises mixed with a little blue; the fuming muriatic acid passes over into the re 184 ACID OF MOLYBDENA. ceiver. This sublimate attracts humidity, and is nothing but the molybdic acid volatilized by the muriatic. This solution of the molybdic acid precipitates silver, mercury, and lead, from their solutions in the nitric acid. It likewise precipitates lead from its solution of the mu- riate of lead, but not the other metals. The molybdic acid takes barytes from the nitric and muriatic acids. In the dry yvay it decomposes the nitrate of potash, and the muriate "of soda; and the acids pass over in the fum- ing state. It disengages the carbonic acid from its combinations, and unites yvith the alkalis. It even partly decomposes the sulphate of potash by the assistance of a strong heat. It dissolves several metals, and assumes a blue colour in proportion as it yields its oxigene to them. The combinations of this acid with the alkalis are lit- tle known. Scheele hoyvever has observed, that fixed al- kali renders this acid earth more soluble in water; that the alkali prevented the acid from rising; that the mo- lybdite of potash is precipitated by cooling in small gra- nulated crystals. The oxigene adheres but slightly to the molybdic base : for this acid boiled yvith the semi-metals does not fail t© assume a blue colour. Hydrogenous gas passed through it is sufficient to pro- duce the blue colour. Molybdena, as Mr. Pelletier has observed, has great resemblance in its chemical results to antimony ; since,, like that semi-metal, it is capable of affording by calci- nation an argentine oxide, capable of vitrification.* * PALLADIUM. This metal is so called from Pallas, the name of the planet disco- vered by Dr. .;.r. 'Pennant used for dissolving this black powder, was similar to that employed by Vauquelin, the alternate action of caustic alkali and an acid. He put a quantity of the powder into a crucible of silver, with a large proportion of pure dry soda, and kept it in a red heat for some time The alkali bein^; then dissolved in water, had acquired a deep orange, or brownish yellow colour, but much of the powder re- mained undissolved. This powder digested m marine acid, gave a dark blue solution, which afterwards became of a dusky olive green, and finally by continuing the heat, of a deep red colour. ' Part of the powder bein^ yet undissolved by the murine acid, was heated as before with alkali; and by the alternate action of the alkali and acid, the whole appeared capable of solution. In order to obtain the compound of iridium and the marine acid in a pur. state. Mr Tennant tried to make it crystallize, by slow evaporation, and succeeded. The iridium may be obtained perfectly pure, merely by exposing these crystals to heat, which expels the oxigene and the muriatic acid. "It appears of a white colour, and is infusible. It will not combine with sulphur and arsenic. Lead ea- sily unites with it; but is separated by cupellation, leaving the iri- dium upon the cupel, as a coarse black powder. C opper forms with it a very malleable alloy, which after cupellation, with the addition of lead, left a small proportion of the iridium, but much less than in the former case. .Silver may be united with it, and the compound remains perfectly malleable. Gold alloyed with iridium, is not freed from it by cupellation, nor by quartation with silver. The compound was malleable, and did not differ much in colour from gold, though the proportion of alloy was very considerable. If the gold or silver is dissolved, the iridium is left in the form of a black powder.* , OSMIUM. This metal has been examined by Vauquelin, Descotil, Fourcroy, and Tennant. The brown yellow alkaline solution, mentioned un- der the head of Iridium, contains it. When this solution is first formed, by adding water to the dry alkaline mass in the crucible, a pungent and peculiar smell is immediately perceived. This smell arises from the extrication of a very volatile metallic oxide, and as this smell is one of its most distinguishing characters, it has been called Osmium. The oxide may be expelled from the alkali by any acid, and ob- tained in solution with water by distillation. The sulphuric acid, being the least volatile, is the most proper for this purpose ; but as, even of this acid, a little is liable to pass over, a second slow distil- lation is required, to obtain the oxide perfectly free from it. The solution procured in this manner is without colour, has a sweetish taste, and a s'rong sme 1. Paper stained blue by violets, was not • Phil. Trans, of the Royal Society of London for i»OS, p. 3i7. t Phil. Trans, of the Royal Society of London for x804, page 411. RHODIUM. 187 changed by it to red ; but by being exposed to the vapour of it in a phialfthe paper lost much of its blue colour, and inclined to grey. Another mode by which the oxide of osmium may be obtained in small quantity, but in a more concentrated state, is by distilling with nitre the original black, powder procured from platina With a degree of heat hardly red. there sublimes into the neck of the retort a fluid apparently oily, but which on cooling con- cretes into a solid, colourless semi-transparent mass. 1 he oxide in this cone -ntrated state, stains the skin of a dark colour, which can- not bo effaced. The most striking test of the oxide of osmium, is an infusion of rails, whicn presently produces a puipie colour, be- coming soon after of a deep vivid blue. 1 he solution of the oxide of osmium with pure ammoniac, becomes somewuat yellow, and slightly so with carbonate of soda, it is not affected by magnesia, nor by chalk ; but with lime a solution is formed, of a bright yel- low colour. The solution of lime gives with galls a deep red preci- pitate, which becomes blue by acids. It produces no effect on a so- lution of platina or gold ; but precipitates lead of a yellowish brown, mercury of a white, and muriate of tin of a brown colour. The oxide of osmium becomes of a dark colour with alkohol, and after some time separates in the form of black films, leaving the al- kohol without colour. The same effect is produced by ether, and much sooner. This oxide appears to part with its oxigene to all the metals, except gold and platina. Silver being kept in a solution of it for some time, acquires a black colour ; but does not entirely deprive it of smell. Copper, tin, zinc, and phosphorus, quickly produce a black or grey powder, and deprive the solution of all smell, and of the power of turning galls of a blue colour. This black-powder, which consists of the osmium in a metallic state, and the oxide of the metal employed to precipitate it, may be dissolved in nitro-mu- riatic acid, and then becomes blue with infusion of galls. If the pure oxide of osmium, dissolved in water, is shaken with mercury, it very soon loses its smell; and the metal, combining with the mercury, forms a perfect amaham. Much of the mercury may be sepa-ated by squeezing it through leather, which retains the amalgam of a firmer consistence. The remaining mercury being distilled off, a powder is left, of a dark grey or blue colour, which is the osmium in its pure state By exposing it to heat with access of air, it evaporates with the usual smell; but if the oxidation is carefully prevented, it does not seem in any decree volatile. Heated with copper and gold, it melted with each of these metals, forming al- loys which were quite malleable. The pure metal does not seem to be acted on by acids.* RHODIUM. This metal is so called, from the rose colour of a dilute solution of the salts containing it. * Phil. Trans, of the Royal Society «f London for i804, page le, and may be called +he cortical coatings, are formed of laminae which themselves consist of the re-union of the common, pro- per, and air vessels of die plant. The vessels are not extended lengthwise along the stem, but are curved in Arai ictis directions; and leave openings or meshes betAveen them, Avhieh are filled by the cellular matter itself. Nothing more is necessary to blk.w the organization, than to macerate these coatings in water, which destroys the cellular substances, and leaves the neMvork uncovered.* The conical coverings are easily detached from each other; and it is from their gross resembiunce to the leaves of a book, that they have been called liber. In propor- tion as these coatings approach the ligneous body, they become hard; and at lengih form the external softer part of the Avood, which Avorkmen call the sap. The bark is the most essential part of the vegetable, by means of Avhieh the principal functions of life, such as nutrition, digestion, the secretions, &c. are performed. All plants and particularly those which are hollow Avithin, and whose products are totally changed by covering them with a different bark, prove evidently that the digestive force eminently resides in this part. The ligneouspart is so far from being essential, that many plants are Avithout it; such as the gramineous and the arundinaceous, and all plants that are hollow within. Grasses, properly speak j * This is most particularly seen in the arbre a dentelle, when the plant has been macerated in water. TEXTURE OF VEGETABLES. 205 ins have only the cortical part. We often see plants in- ternally rotten, but kept in vigour by the good state of their bark. ARTICLE II. Concerning the Ligneous Texture. Beneath the bark there is a solid substance, which forms the trunk of trees, and appears to be usually com- posed of concentric layers. The interior coatings or rings are harder than the exterior; they are older, and of a more firm and close grain. The hardest of these form the Avood, properly so called, while the softer external rings constitute the sap. We may consider wood as being formed of fibres, more or less longitudinal, con- nected together by a cellular tissue, interspersed with ve- sicles communicating with each other; Avhieh diminish gradually towards the centre, where they form the pith. The pith is found only in young branches or plants, and disappears in plants of a certain age. The vesicular tissue bears a great analogy Avith the glandular and lymphatic vessels of the human body: in both, the conformation and uses are the same. In the early age of plants and animals, the organs have a consider- able expansion, because the increase of the individual is very rapid at that period. But, as age advances, the vessels become obliterated in both kingdoms; and it is observed that, in the white woods and fungi Avhieh abound with the vesicular substance, the growth is also very- rapid. 206 STRUCTURE OF VEGETABLES. , ARTICLE III. Concerning the Vessels. The various humours of vegetables are contained in cer- tain appropriated vessels, in which they enjoy a degree of motion that has been compared to the circulation in ani- m:us. It differs from it, hoAvever; because these hu- mours are not continually kept in equilibrio in the vessels by an inherent force, but receive in a more evident man- ner th6 impression of external agents. Light and heat are the two great causes which determine and modify the motion of the fluids and vegetables. These agents cause the sap to rise into the various parts, where it is elabo- rated in a manner correspondent to the functions of each; but it is not observed that it returns : so that the acces-. sion or flux of the humours in vegetables is proved, but the reflux does not appear to be perceptible. Three kinds of vessels may be distinguished in vege- tables : the common, or sap vessels; the proper vessels; and the air vessels, or tracheae. 1. The sap vessels convey the sap, or general humour, from Avhieh all the others are derived. This liquor may be compared to the blood in animals. These vessels are reservoirs from Avhieh the several organs extract the different juices, and elaborate them in a proper manner. The sap vessels chiefly occupy the middle of plants and trees. They rise perpendicularly, though Aviih de- flections sideAvays, so as to communicate with ail the parts of the vegetable. They convey the sap into the utricu- les; whence it is taken by the proper vessels, in order diat it may be duly elaborated. 2. Each organ is likewise provided AAith peculiar vessels, to separate the various juices, and to preserve them, Avithout suffering them to mix Avith the generd muss of humours. Thus it is that we find in the same ve- STRUCTURE OF VEGETABLES. 207 cetable, and frequently in the same organ, juices of different natures, and gready differing in colour and consistence. The vessels, whether common or proper, are retain- ed in their several directions by the ligneous fibres; they are every where surrounded by the cellular tissue; they open, and pour their fluid into glands, into the cellu- lar tissue, and into the utricules, to answer the various functions. . The utricules are small vessels or repositories which contain the pith, and frequently the colouring mat- ter. They form a kind of repository in which the nutritive juice of the plant is preserved, and whence it is taken on occasion; in the same manner as the collection of marrow is formed in the internal part of the bones, whence it is afterwards extracted when the animal is not sufficiently supplied with nutri- ment. 3. The tracheae, or air vessels, appear to be the organs of respiration, or rather those which receive the air, and facilitate its absorption and decomposition. They are called tracheae on account of the resemblance Avhieh is thought to exist between them and the respiratory organs of insects. In order, to observe them, a branch of a tree is taken sufficiently young to break off short: after having cleared away the bark without touching the wood, the bough is broken by dravving the two extremities in oppo- site directions; the tracheae are then seen in the form of small corkscrews, or vessels turned in a spiral direction. It is generally supposed that the large pores which are perceived in the transverse section of a plant, viewed in the microscope, are merely air vessels. It often happens that the sap is extravasated in the cavity of the tracheae; and they appear incapable of serving any other purposes than that of conveying the air, at least for some time, unless a change takes place in the life of the plant. 208 NUTRITION OF VEGETABLES. ARTICLE IV. Concerning the Glands. Small protuberances are observed upon various parts of vegetables. These are glandular bodies whose form is prodigiously varied. It is more particularly upon this variation of form that Mr Guettard has grounded his seven species. They are almost always filled with a humour, whose colour and nature are singularly varied. SECTION II. Concerning the Nutritive Principles of Vegetables. IF plants were to perform no other act than that of pumping the nutritive principles they contain out of the earth ; if they did not possess the faculty of digesting, assimilating them, and forming different products, ac-] cording to their nature, and the diversity of their organs; it would follow as a consequence, that we ought to find in the earth all those principles AA'hich analysis exhibits to us in vegetables: a conclusion which is contradicted by the facts; for we sliall hereafter prove that the production of vegetable earth is an effect of the organization of plants, and that it OAves its formation to them instead of commu- nicating principles ready formed to those individuals If it Avere true that plants did nothing but extract their component parts out of the earth, those plants which grow on the same soil Avould possess the same principles, or at least the analogy between them Avould be very great; NUTRITION OF VEGETABLES. 209 whereas we find plants of very different virtues and flav- ours grow and flourish beside each other. In addition to this we may observe, that' such plants as are raised in pure water—the fat plants, which grow vyithout being fixed to the earth, provided they are placed in a moist at- mosphere—the class of parasitical plants, which do not partake of the properties of those which serve to support them—prove that a vegetable does not derive its juices from the earth, on account of its being earth; but that it possesses an internal alterative and assimilating power, which appropriates to each individual the aliment which is suitable to it, at the same time that it disposes and com- bines that aliment to form certain peculiar principles. This digestive virtue will appear to be astonishingly per- fect, when it is considered that the nutriment common. to all vegetables is very little varied, since we know only of the water and air; and consequently that it possesses the power of forming very different products with these two simple principles. But from this circumstance, that the nutritive principles of plants are very simple, it must be presumed that, in the various results of digestion, or (which is the same thing) in the vegetable solids and fluids, there must be the greatest analogy; and that the differences are deducible from the proportion of the prin- ciples, and their more or less perfect combination, rather than from their variety. With this intention Ave shall carefully observe the transition from one principle to ano- ther ; and shall explain the art of reducing them all to certain elementary or primitive substances, such as the fibrous matter, mucilage, &c. ARTICLE I. Concerning Water, as a Nutritive Principle of Plants. Every one knows that a plant cannot vegetate without the assistance of water: but it is not so generally known that this is the only aliment Avhieh the root draws from Vol. II. D d 21Q. NUTRITION OF VEGETABLES. the earth; and that a plant can live, and propagate itself, without any other assistance than the contact of Avater and air. It apppears to me, nevertheless, that the following experiments remove every doubt on this subject: Van Helmont planted a willoAv, Aveighing fifty pounds, in a certain quantity of earth covered Avith sheet lead: he watered it for five years AAith distilled water; and at the end of that time the tree Aveighed one hundred sixty- nine pounds three ounces, and the earth in which it had vegetated Avas found to have suffered a loss of no more than three ounces. Boyle repeated the same experiment upon a plant, which at the end of tAvo years weighed fourteen pounds more, Avithout the earth in which it had vegetated having lost any perceptible portion of its weight. Messrs. Duhamel and Bonnett supported plants with moss, and fed them with mere water; they observe^ that the vegetation was of the most vigorous kind: and the naturalist of Geneva observes, that the flowers were more odoriferous, and the fruit of a high flavour. Care Avas taken to change the supports before they could suffer any alteration. Mr. Tillet has likeAvise raised plants, more especially of the gramineous kind, in a similar manner; with this difference only, that his sup- ports Avere pounded glass, or quartz in powder. Hales has observed that a plant which weighed three pounds gained three ounces after a heavy dew. Do we not every day observe hyacinths and other bulbous plants, as well as gramineous plants, raised in saucers or botdes contain- ing mere Avater. All plants do not demand the same quantity of water; and nature has varied the organs of the several individuals conformably to the necessity of their being supplied Avith this food. Plants which transpire little, such as the mos- ses and the lichens, have no need of a considerable quan- tity of this fluid; and accordingly they are fixed upon dry rocks, and have scarcely any roots; but plants which require a larger quantity have roots which extend to a great distance, and absorb humidity throughout their whole surface. The leaves of plants have likewise the property of ab- sorbing water, and of extracting from the atmosphere the NUTRITION OF VEGETABLES. 211* same principle which the root draAvs from the earth. But plants which live in the Avater, and as it were sAvim in the element which serves them for food, have no need of roots; they receive the fluid at all their pores : and we accordingly find that the fucus, the uiva, Sec. have no roots Avhatever. The purer the Avater, the more saltnury it is to plants. Mr. Duhamel has draAvn this conseouence from a series of well-made experiments, by which he has proved that water impregnated with salts is fatal to vege- tation. Hales caused them to absorb various fluids, by making incisions in their roots, and piunging them in spi- rits of Avine, mercury, and various saline solutions; but he was convinced that these were all poisons to the vege- tables. Besides, if these salts Avere favourable to the plants, they Avould be again found in the individual which hud been watered with a solution of them; whereas Messrs. Thouvenel and Cornette have proved that these salts do not pass into the vegetable. We must, nevertheless, ex- cept the marine plants, because the sea salt of which they have need is decomposed in them; and produces a prin- ciple which appears necessary to their existence, since they languish without it. Though, it is proved that pure water is more proper for vegetation than water charged with salts, it must not on that account be concluded that Avater cannot be disposed in a more favourable manner to the development of ve- getables, by charging it Avith the remains of vegetable and animal decomposition. If, for example, the water be loaded with principles disengaged by fermentation or putrefaction, the plant then receives juices already assi- milated to its nature; and these prepared aliments must hasten its growth. Independent of those juices already formed, the nitrogene gas, which constitutes one of the nutritive principles of plants, and is abundantly afforded by the alteration of vegetables and animals, must facili- tate their development. A plant supported by the re- mains of vegetables and animals is in the same situation as an animal fed on milk only; its organs have less diffi- culty in elaborating this drink than that which has not yet been animalized. ^ The dung which is mixed Avith earths, and decomposed* not only affords the alimentary principles we have spoken 212 NUTRITION OF VEGETABLES. of; but likeAvise favours the groAvth of the plant by that constant and steady heat which ulterior decomposition pro- duces. Thus it is that Fabroni affirms his having observ- ed the development of leaves and flowers, in that part of a tree only, which was in the vicinity of a heap of dung. ARTICLE n. Concerning Earth, and its Influence in Vegetation. Although it be well proved that pure water is sufficient for the support of plants, we must not consider the earth as of no use. Its utility resembles that of the placenta, which of itself affords no support to the life of the infant, but Avhieh prepares and disposes the blood of the mother to become a suitable nourishment: or it resembles, and has a similar utility Avith the various reservoirs which na- ture has placed in the body of man, to preserve the seve- ral humours, and emit them upon occasion. The earth imbibes and retains Avater; it is the reservoir destined by nature to preserve the elementary juice which the plant continually requires ; and to furnish that fluid in propor- tion to its wants, without, exposing it to the equally fatal alternatives of being either inundated or dried up. We even see that, in the young plant or embryo, na- ture has not chosen to entrust the labour of digestion to the still feeble germen. The seed is formed of a paren- chyma, which imbibes Avater, elaborates it, and does not transmit it to the germen until it is reduced into juice or humour. By insensible gradations this seed is destroyed; and the plant, become sufficiently strong, performs the work of digestion Avithout assistance. In the same man- ner it is that we perceive the foetus supported in the Avomb of its mother by the humours of the mother herself; but, when it has seen the light, it receives for nourishment a -fluid less animalized, its organs are gradually strength- ened, and at length become capable of digesting a stronger and less assimilated nourishment But on this very account, that the earth is destined to transmit to the plant that Avater Avhieh is to support it, the nature of the soil cannot be a matter of indifference, but NUTRITION OF VEGETABLES. 113 must be varied accordingly as the plant requires a more or less considerable quantity of water, accordingly as it demands more or less in a given time, and accordingly as its roots extend to a greater or less distance. It may therefore be immediately perceived that every kind of earth is not suitable for every plant, and consequently that a slip cannot be grafted indifferently upon every species. A proper soil is that—1. Which affords a sufficientiy firm support to prevent the plant from being shaken. 2. Which permits the roots to extend themselves' to a dis- tance with ease. 3. Which becomes impregnated with humidity, and retains the water sufficiendy that the plant may not be without it when wanted.—To answer these several conditions, it is necessary to make a proper mix- ture of the primitive earths, for none of them in particu- lar possesses them. Siliceous and calcareous earths may be considered as hot and drying, the argillaceous as moist and cold, and the magnesian as possessing intermediate properties. Each in particular has its faults, which ren- der it unfit for culture : clay absorbs water, but does not communicate it; calcareous earth receives and gives it too quickly: but the properties of these earths are so happily opjposed, that they correct each other by mixture. Accordingly we find that, by adding lime to an argillace- ous earth, this last is divided; and the drying property of the lime is mitigated, at the same time that the stiffness of the clay is diminished. On these accounts it is that a single earth cannot constitute manure; and that the cha- racter of the earth intended to be meliorated ought to be studied, before the choice of any addition is decided on. Mr. Tillet has proved that the best proportions of a fer- tile earth for corn, are three-eighths of clay, two eighths of sand, and three-eighths of the fragments of hard stone. The advantage of tilling consists in dividing the earth, aerating it, destroying useless or noxious plants, and con- verting them into manure, by facilitating their decompo- sition. Before we had acquired a knowledge of the constituent principles of water, it was impossible to explain, or even to conceive, the growth of plants by this single aliment. In fact, if the water Avere an element, or indecomposable principle, it would afford nothing but water in entering 214 NUTRITION OF VEGETABLES. into the nutrition of the plant, and the vegetable would of course exhibit that fluid only : but when we consider wa- ter as formed by the combination of the oxigenous and hydrogenous gases it is easily understood that this com- pound is reduced to its principles ; and that the hydroge- nous gas becomes a principle of the vegetable, Avhile the oxigene is thrown off by the vital forces. Accordingly we see the vegetable almost entirely formed of hydrogene. Oils, resins, and mucilage, consist of scarcely any thing but this substance; and we perceive the oxigenous gas escape by the pores, where the action of light causes its disengagement. This decomposition of water is proved not only in vegetable, but likewise in animal bodies. Ron- delet (Lib. de Pise. lib. i. cap. xii.) cites a great number of examples of marine animals which cannot subsist but by means of water, by the very constitution of their organs. He affirms that he kept, during three years, a fish in a vessel constandy maintained full of very pure water: it grew to such a size, that at the end of that time the ves- sel coujd no longer contain it. He relates this as a very common fact. We likewise observe the red fishes, which are kept in glass vessels, are nourished, and grow, Avith- out any other assistance than that of the water properly reneAved. ARTICLE III. Concerning Nitrogenous Gas, as a Nutritive Principle of Plants. Vegetables cannot live without air; but the air they re- quire is not the same as is appropriated to man. Drs. Priestley, Ingenhousz,andMr. Senebier,have proved that it is the nitrogenous gas which more particularly serves them for aliment.* Hence it arises that vegetation is more vigorous Avhen a greater quantity of those bodies Avhieh * If this opinion was just, vegetables growing in atmospheric air would abstract the nitrogene gas, and render it purer, but this is never the case. A branch of Sedum Telephium, a vigorous ever- green, will grow twenty days in the air of the atmosphere, and produce no effe«t upon it.—Am, Ed. SUTRITIOJf OF VEGETABLES. 215 afford this gas by their decomposition are presented to the plant; these are, animals or vegetables in a state of pu- trefaction. As the basis of nitrogenous gas is unknoAvfi to us, it is difficult to conceive what may be its effect upon the vegetable economy, and we cannot follow it af- ter its introduction into the vegetable. We do not find it again until the decomposition of the vegetable itself when it re-appears in its gaseous form. ARTICLE IV Concerning the Carbonic Acid, as a Nutritive Principle of Vegetables. The carbonic acid which is dispersed in the atmosphere, or in waters, may likewise be considered as an aliment of plants; for these bodies possess the power of absorbing and decomposing it when its quantity is small. The base of this acid even seems to contribute to the formation of vegetable fibres : for I have observed that this acid pre- dominates in the fungus, and other subterraneous plants. But by causing these vegetables, together Avith the body upon which they were fixed, to pass by imperceptible gradations from an almost absolute darkness into the light, the acid very nearly disappeared ; the vegetable fibres be- ing proportionally increased, at the same time that the re- sin and colouring principles Avere deA'eloped by the oxi- gene of the same acid. Senebier has observed, that the plants which he watered with water impregnated Avith the carbonic acid, transpirt d a much greater quantity of ox- igenous gas; which proves a decomposition of the car- bonic acid. Vegetation may therefore be successfully employed to correct air too highly charged with carbonic acid, or in Avhieh the nitrogenous gas exists in too great a pro- portion. 216 TEMPERATURE OF VEGETABLES. ARTICLE V. Concerning Light, and its Influence on Vegetation* - Light is absolutely necessary to plants. Without the assistance of this principle they become pale, languish, and die. But it has not been proved that it enters as an ali- ment into their composition: at most it may be consider- ed as a stimulus or agent which decomposes the various nutritiA'e principles, and separates the oxigenous gas aris- ing from the decomposition of the carbonic acid, while dieir bases become fixed in the plant itself. The most immediate effect of the fixation of the vari- ous substances, and the concretion of the liquids, which serve as the food of plants, is a sensible production of heat, which causes plants to participate \rery little in the temperature of the atmosphere. Dr. Hunter observed, by keeping a thermometer plunged in a hole made in a sound tree, that it constantly indicated a temperature several de- grees above that of the atmosphere, when it was below the fifty-sixth division of Fahrenheit; whereas the vegetable heat in hotter Aveather, was always several degrees below that of the atmosphere. The same philosopher has like- wise observed, that the sap, which out of the tree Avould freeze at 32°, did not freeze in the tree unless the cold were augmented 15° more. The vegetable heat may increase or diminish, by se- veral causes, of the nature of disease ; and it may even become perceptible to the touch in very cold weather, ac- cording to Mr. Buffon. The heat produced in healthy vegetables, by the before- mentioned causes continually tempers the cold of the at- mosphere ; the evaporation Avhieh takes place through the whole body of the tree, continually moderates the scorch- ing heat of the sun: and these productive causes of cold or heat are more effectual, in proportion as the heat or cold of external bodies acts with greater energy. The property which plants possess of converting ni- trogenous gas and carbonic acid into nourishment, esta- blishes an astonishing degree of analogy between them and RESULTS OF NUTRITION. 217 Certain insects. It appears, from the observation of Fre- deric Gorman (Ephem. des Curios. Nat. Ann6e 1670), that the air may become a real food for the class of spi- ders. The larvae of the ant, as well as of several insects of prey which live in the sand, increase in bulk, and un- dergo their metamorphoses without any other nourishment than that of the air. It has been observed that a great number of insects, particularly in the state of larvae, are capable of living in the nitrogenous gas, mixed with car- bonic acid, and transpiring vital air. The abbe Fontana has observed that several insects possess this property ; and Ingenhousz, who is of opinion that the green matter which is formed in AA'ater, and transpires oxigenous gas by the light of the sun, is a cluster of animalculae, has added to these phenomena.* Insects have moreover the organ of respiration distributed over the whole surface of their bodies. Here therefore Ave observe severalvery asto- nishing points of analogy between insects and vegetables : and the chymical analysis adds still more to these resem- blances, since insects and vegetables afford the same prin- ciples ; namely, volatile oils, resins, disengaged acids, &c. SECTION III. Concerning the Results of Nutrition, or the Vegetable Principles. THE various substances which afford food to plants, are changed by the organization of the vegetable • from which there results a fluid generally distributed, and known by the name of Sap. This juice when conveyed into the several parts of the plant, receives an infinity of modifications, and forms the several humours which are separated and aftbrded by the organs. It is to these principles chiefly that we are at present about to direct * This green matter is now considered by all philosophers, to be a vegetable substance.—Am. Ed. Vol. II. Ee 218 MUCILAGE. our attention; and Ave shall endeavour in our examination to folloAv the most natural order, by subjecting ihem to analysis in the same order as that in Avhieh nature pre- sents them to us. ARTICLE II. Concerning Mucilage. Mucilage appears to constitute the first alteration of the alimentary juices in vegetables. Most seeds are almost totally resolvable into mucilage, and young plants seem to be entirely formed of it. This substance has the greatest analogy Avith the mucous fluid of animals. Like that fluid, it is most abundant in the earlier periods of life; and all the other principles appear to be derived from it; and in vegetables, as AA'ell as animals, its quan- tity becomes less in proportion as the increase of magni- tude, or growth of the individual, becomes less, or ceases. Mucilage is not only the nutritive juice of plants and animals; but, Avhen extracted from either, it be- comes the most nourishing and Avholesome food Ave are acquainted Avith. Mucilage forms the basis of the proper juices, or the sap of plants. It is sometimes found almost entirely alone, as in malloA\rs, the seeds of the wild quince, lin- seed, the seeds of thlaspi, &c. Sometimes it is com- bined Avith substances insoluble in Avater, Avhieh it keeps suspended in the form of an emulsion; as in the euphor- bium, celandine, the convolvulus, and others. In other instances it is united Avith an oil, and forms the fat oils. Frequently it is united A\ith sugar; as in the gramineous seeds, the sugar-cane, muize, carrot, &c. It is likeAvise found confounded Avith the essential salts, Avith excess of acid, as in barberries, tamarinds, sorrel, &c. Mucilage sometimes constitutes the permanent state of the plant; as in the tremella, the conferva, some lichens, and most of the champignons. This exist- ence in the form of mucilage is likewise seen in certain GUMS. 219 animals; such as the medusa or sea-nettle, the holothu- rion, &c. The characters of mucilage are—1. Insipidity. 2. Solubility in water. 3. Insolubility in alcohol. 4. Coa- gulation by the action of weak acids. 5. The eun ..sion of a considerable quantity of carbonic acid, when ex- posed to the action of fire; at the same time that ii be- comes converted into coal, without exhibiting any rLme. Mucilage is likeAvise capable of passing to the acid fermen- tation Avhen diluted with water. The formation of mucilage appears to be almost in- dependent of light. Those plants which grow in sub- terraneous places abound with it. But light is required to enable mucilage to pass to other states; for, without the assistance of this principle, the same plants would obtain scarcely any consistence. That which is called gum, or gummy juices, in com- merce, is nothing but dried mucilage. These gums are three in number. They either flow naturally from the trunk of the tree which affords them, or they are obtained by incision of the bark. 1. Gums of the country, Gummi nostras.— This gum flows naturally from certain trees in our climate, such as the plum, the peach, the cherry-tree, &c. It first appears in the form of a thick fluid, Avhieh congeals by exposure to the air, and loses the adhesive and gluey consistence which characterizes it in the liquid state. Its colour is white, but more commonly yelloAv or reddish. When pure, it may be advantageously substituted for gum ara- bic, Avhieh is much dearer. 2. Gum arabic.—The gum arabic flows naturally from the acacia in Egypt and Arabia. It is even affirmed that it is not obtained from this tree only, but that the gum met Avith in commerce is the produce of several trees. The appearance of this gum is in round pieces, AA'hite and transparent, wrinkled Avithout and IioIIoav within; it is likeAA'ise found in round pieces variously contorted. This gum is easily soluble in Avater, and forms a transparent jelly called mucilage. It is much used in the arts and in medicine. It is mild, void of smell or taste, very well adapted to serve as the basis of pastils, and other prepar- :tfions used as mitigating or softening remedies. S$0 GUMS. 3. Qum adragant.—The gum adragant is nearly of the same nature as gum arabic. It flows from the adragant of Crete, a small shrub not exceeding three feet in height. It comes to us in small white tears, contorted, and resembling little Avorms. It forms Avith water a thick- er jelly than gum arabic, and may be used for the same purposes. If the roots of marshmalloAvs or of the consolida, linseed, the kernels of the wild quince (coing), &c. be macerated in Avater for a time they afford a mucilage similar to that of gum arabic. Ail these gums afford by distillation, water, an acid, a small quantity of oil, a small quantity of ammoniac or vo- latile alkali, and much coal. This sketch of analysis proves that mucilage is composed only of Avater, oil, acid, carbone, and earth; and shews that the various princi- ples of the alimentary juices, such as water, the carbonic acid, and nitrogene gas, are scarcely changed in this gubstance. Gums are used in the arts and in medicine. In the arts they are applied to give a greater degree of consistence to certain colours, and to fix them more permanently upon paper; they are also used as a preparation to give a firmer body to hats, ribands, taffetas, &c. Stuffs dipped in gum AA^ater acquire a lustre and brightness; but water, and the handling of these goods, soon destroy the illusion; and these processes are classed among those Avhieh nearly approach to imposition and deceit. Gum is likeAvise the basis of most kinds of blacking used for shoes, boots, and the like. The gums are ordered in medicine as emollients. They compose the basis of many remedies of this kind. The mucilage of linseed, or of the ker- nels of Avild quinces, is of value in allaying inflamma- tions. FIXED AND VOLATILE OILS. 221 ARTICLE II. Concerning Oils. By common consent the name of Oil is given to fat unctuous substances, more or less fluid, insoluble in Avater, and combustible. These products appear to belong exclusively to ani- mals and vegetables. The mineral kingdom exhibits only a few substances of this nature, which possess scarcely any of the above properties, such as the unctu- ous property. Oils are distinguished, relative to their fixity, into fat oils, and essential oils. We shall describe them in this article under the names of Fixed Oils and Volatile Oils. The difference between these Iavo kinds of oils do not merely consist in their various degrees of vola- tility, but also in their habitudes Avith the several re-agents. The fixed oils are insoluble in alcohol, but the volatile oils are easily dissolved: the fixed oils are in general mild ; while the volatile are acrid and even caustic. It appears nevertheless that the oily principle is the same in both; but it is combined Avith mucilage in the fixed oils, and with the spiritus rector, or aroma, in the volatile oils. By burning the mucilage of fixed oils by dis- tillation, they become more and more attenuated; the same may likeAvise be done by means of Avater, which dissolves this principle. By distilling volatile oil with a small quan- tity of water, by the gentle heat of a AA^ater bath, the aroma is separated; and this may be again restored by re-distilling it with the odorant plant Avhieh originally afforded it. Volatile oil is usually found in the most odorant part of any plant. In umbelliferous plants it is found in the seed; in the geum, the root affords it; and in the labiated plants it is found in the branches and leaves. The simi- 222 FIXED OILS. litude between volatile oils and ether, Avhieh appears to be merely a combination of oxigene and alcohol, proves that the volatile oils may be nothing but a combination of the fermentescible basis of sugar with oxigene. Hence Ave may form a notion how oil is formed in the distil- lation of mucilage and of sugar; and Ave shall no longer be surprised to find that the volatile oils are acrid and corrosive, that they redden blue paper, attack and destroy cork, and approach to the properties of acids. We shall now proceed to treat of fixed and volatile oils separately. DIVISION I. Concerning Fixed Oils. Most of the fixed oils are fluid; but the greater num- ber are capable of passing to the state of solidity, even by a moderate degree of cold. There are some which constandy possess that form in the temperature of our climates; such as the butter of cacao, Avax, and the pe- la of the Chinese. They all congeal at different degrees of cold. Olive oils become solid at 10° below zero of Reaumur; oil of almonds at the same degree; but nut- oil does not freeze in our climates. The fixed oils possess a very evident degree of uncn_i- osity, do not mix either Avidi Avater or alcohol, are vola- tilized at a degree of heat superior to that of boiling Ava- ter, and when volatilized they take fire by the contact of an ignited body. The fixed oils are contained in the kernels of shell fruits or nuts ; in the pippins, and sometimes in all the parts of fruits, such as olives and almonds, all whose parts are ca- pable of affording them. The oil is usually made to flow by expression out of the cellules which contain it: but each species requires a different management. 1. Olive oil is obtained by expression from the fruit of the olive tree. The process used by us is very simple. OIL OF ALMONDS. 223 The olive is crushed by a mill-stone, placed vertically, rolling upon an horizontal plane. The paste thus formed is strongly pressed in a press; and the first oil which comes out is called Virgin Oil. The marc or pulp is then moistened with boiling Avater; the mass is again pressed; and the oil Avhieh floats upon the water carries Avith it part of the parenchyma of the fruit, and a great part of the mucilage, from Avhieh it is difficultly cleared. The difference in the kind of olive produces a differ- ence in the oil; but the concurrent circumstances likewise establish other differences. If the olive be not sufficiently 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 sufficiently clean ; the mill-stones, and all the uten- sils, are impregnated with a rancid oil, which cannot but communicate its flavour to the new oil. In some coun- tries it is usual to lay the olives in heaps, and suffer them to ferment before the oil is drawn. By this management the oil is bad ; and this process can only be used for oil intended for the lamp or for the soap-boiler. 2. Oil of almonds is extracted from that fruit by ex- pression. For this purpose dry almonds are put into a coarse sack, and agitated rather strongly, to 'disengage an acrid powder Avhieh adheres to the skin. They are then pounded in a marble mortar into a paste, Avhich is wrapped in a coarse cloth, and subjected to the press. This oil is greenish and turbid when fresh, because the action of the press causes part of the mucilage to pass through the cloth; as it becomes older it is clearer, but is acrid by the decomposition of the same mucilage. Some persons throw almonds into hot water, or ex- pose them to steam, before they press them; but this ad- dition of water disposes the oils to become rancid more speedily. By this process the oil of all kinds of almonds, nuts, and seeds, may be extracted. 3. Linseed oil is extracted from the seed of the plant linum. As this seed contains much mucilage, it is torre- fied before it is subjected to the press. This previous treatment gives the oil a disagreeable empyreumatic fla- vour ; but at die same time Deprives it of the property of 224 FROPERTIES OF OIL. becoming rancid, and renders it one of the most drying oils. All mucilaginous seeds, all kernels, and the seeds of henbane and of the poppy, ought to be treated in the same manner. If a fat oil be distilled in a proper apparatus of vessels, the product is, phlegm; an acid; a fluid or light oil, Avhich becomes thicker towards the end; much hydroge- nous gas, mixed A\ith carbonic acid; and a coaly residue, which affords no alkali. I have observed that the volatile oils afford more hydrogenous gas, and the fixed more car- bonic acid: this last product depends on the mucilage. By distilling the same oil repeatedly, it is more and more attenuated, becomes very limpid and very volatile, Avith ^the only difference that it has required the peculiar odour communicated by the fire. The volatilization of the oil may be accelerated by distilling 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, Avhen distilled once or tAvice from clay alone, such as that of Murviel, are rendered perfectly colourless. The an- cient chemists prepared oleum philosophorum by distilling oil from a brick previously impregnated with it. 1. Oil easily combines with oxigene. This combina- tion is either sIoav or rapid. In the first case, rancidity is the consequence ; in the second inflammation. Fixed oil exposed for a certain time to the open air, ab-' sorbs the oxigenous gas, and acquires a peculiar odour of fire, an acrid and burnt taste, at the same time that it be- comes thick and coloured. If oil be put in contact with oxigene in a bottle, it becomes more speedily rancid, and the oxigene is absorbed. Scheele observed the absorp- tion of a portion of the air before the theory was well ascertained. Oil is not subject to alteration in closed vessels. It seems that oxigene, combined with the mucilage, constitutes rancidity ; and that, when combined with the oil itself, it forms drying oil. The rancidity of oils is therefore an effect analogous to the calcination or oxidation of metals. It essentially de- pends on the combination of pure air Avith the extractive principle, Avhich is naturally united with the oily princi- ple. We may carry this inference to demonstration, by PURIFICATION OF OILS. 225 attending to the processes used to counteract or prevent the rancidity of oils. A. When olives are prepared for the table, every endea- vour is used to deprive them of this principle, Avhichde- termines their fermentation; and for this purpose various methods are used.' . In some places they are macerated in boiling water, charged Avith salt and aromatics; and, af- ter twenty-four hours digestion, they are steeped in clear water, Avhich is renewed* until their taste is perfectly mild. Sometimes nothing more is done than to macerate the olives in cold water; but they are frequently macerated in a lixivium of quick-lime and Avood ashes, aftar Avhicri they are Avashed in clear Avater. But in whatever manner the preparation is made, they are preserved in a pickle charg- ed with some aromatic plant, such as coriander and fen- nel. Some persons preserve them Avhole; others split them, for the more complete extraction of their mucilage, and in order that they may be more perfectly impregnated with the aromatics. All these processes evidently tend to extract the muci- laginous principle, which is soluble in Avater, and by this means to preserve the fruit from fermentation. When the operation is not well made, the olives ferment and change. If olives be treated AAith boiling Avater, to extract the mu- cilage, before they are submitted to the press, a fine oil Avill be obtained, without danger of rancidity. B. When the oil is made, if it be strongly agitated in Avater, the mucilaginous principle is disengaged ; and the oil may be afterwards preserved for a long time without change. I have preserved oil of the marc of olives, pre- pared in this manner, for several years, in open bottles, without any alteration. C. The torrefaction to Avhich several mucilaginous seeds are subjected'before the extraction of the oil, ren- ders them less susceptible of change, because the muci- lage has been destroyed. D. M. Sieffert has proposed to ferment oils Avith apples or pears, in order to deprive rancid oils of their acrimony. By this means they are cleared of the principle which had combined with diem, but now becomes attached to other bodies. Vol. II. F f 226 COMBINATIONS OF OILS. Mucilage may therefore be considered as the seed of fermentation. When the combination of the pure air is favoured by the volatilization of the oil, inflammation and combustion are then the consequence. To cany this combination into effect, the oil must be volatilized by the application of a heated body; and the flame Avhich is produced is then sufficient to maintain the degree of volatility, and sup- port the combustion. When a current of air is caused to pass through the middle of the wick and the flame, die great quaniitv of oxigene Avhich must then necessarily pass, occasions a more rapid combustion. Hence it is that the light is stronger, and without smoke ; for this is destroyed and consumed by the violent heat AArhich is ex- cited. The lamps of Palmer are likewise entitled to our par- ticular attention. By causing the rays to pass through a liquor coloured blue, lie peifectly imitates the light of the day ; Avhich proves that the artificial rays require to be mixed Avith the blue, to imitate the natural: and the solar rays which pass through the atmosphere, may owe their colour to their combination Avith the blue colour Avhich appears to predominate in the air. If Avater be projected upon oil in a state of inflamma- tion, it is known that extinction does not happen, because the water is decomposed in this experiment. If the pro- duct of the combustion of oil be collected, much water is obtained, because the combination of its hydrogene with oxigene produces that fluid. Mr. LaA'oisicr has proved that one pound of olive oil contains, Coal or carbone, 12 ounces, 5 gross, 5 grains; Hydrogene, - 3 — 2 — 67. The art of rendering oils drying, likewise depends on the combination of oxigene Avith the oil itself. For this purpose, nothing more is required than to boil it aa ith oxides. If an oil be heated upon the red oxide of mer- cury, a considerable ebullition ensues, the mercury is reduced, and the oil becomes very drying: tiiis is an obsei valion of Mr. Puyniaiirin. The oxides of lead or copper are commonly used for this purpose. An ex- change of principles takes place in this operation; the MANUFACTURE OF SOAPS. 227 mucilage combines with the metal, while the oxigene unites Avith the oil. Oil may likewise be combined Aviih the metallic oxides by double affinity, after the manner of Berthollet. For this purpose a solution of soap is poured into a metal- lic solution. By this means a soap of a green colour is prepared Avith a sulphate of copper; and, Avith that of iron, a soap of a deep brown colour, of considerable intensity. It appears that, in the combinations of fixed oils Avith the oxides of lead, a substance is disengaged, and sAvims at the top, which Scheele called the Sweet Principle, and seems to be simply mucilage. 2. OH combines Avith sugar, and affords a kind of soap, Avhich may be easily diffused in Avater, and kept sus- pended. The trituration of almonds with sugar and Avater, forms the lac amygdale, orgeat, and other emulsions. Combinations of this kind exist ready formed in the ve. getable kingdom. 3. Oil unites readily Avith alkalis; and the result of this union is the Avell knoAvn compound soap. To this effect potash or pure alkali may be triturated with oil, and the mixture concentrated by fire. The medicinal soap is made Avith oil of sweet almonds, and half its weight of potash or caustic alkali. The soap becomes hard by standing. To make the. soap of commerce, one part of good soda of Alicant must be boiled with two of quicklime; in a sufficient quantity of water. The liquor is then to be strained through a cloth; and evaporated to that degree, that a phial Avhich contains eight ounces of pure water, may hold eleven of the saline solution, which is usually called Soap Lye or Lees. One part of this lixivium, and two of oil, boiled together, till upon trial with a spatula it easily separates, and soon coagulates, form soap. In most manufactories the lixivium is prepared without heat. Equal volumes of pounded soda of Alicant, and quicklime previously slacked, are mixed together. ' Wa- ter is thrown on this mixture, which- filters through, and is conveyed into a proper vessel. Water is poured on till it passes through without acquiring any more salt. lit 228 MANUFACTURE OF SOAPS. this way these kinds of leys are obtained, Avhich differ in strength; that which passes first is the strongest, and the last is almost mere water. These are afterwards mix- ed Avith oil in boilers, where the mixture is favoured by htat. The weak lye is first added, and afterwards grad- ually the stronger; and the strongest is not added till to- Avards the end of the process. To make the soap marbled, they make use of soda in the mass, blue copperas, cinnabar, &c. according to the colour desired. A liquid green or black soap is likeAvise made by boil- ing the lixivium of soda, potash, or even wood ashes, with the marc of the oils of olive, of nuts or of nape; or Avith fat, or fish oil, &c. The black soap is made in Picardy, and the green in Holland. The Marquis de Bouillon has proposed to make soaps with animal fat.* At Aniane, and in the neighbourhood of Montpellier, a soft soap is prepared Avith caustic lixivium of wood ashes, and the oil or the marc of olives. If soap be exposed to distillation, the result is Avater, oil, and much ammoniac; and there remains in the retort a large quantity of the alkali used in the fabrication of the soap. The ammoniac Avhich is produced in this experi- ment, appears to me to arise from the combination of the hydrogenous gas of the oil with the nitrogene, a constitu- ent principle of the fixed alkali. Soap is soluble in pure water; but it forms curds, and is decomposed in water abounding with sulphates : because the sulphuric acid seizes the alkali of the soap; while the earth combines with the oil, and forms a soap Avhich swims at the surface. Soap is likeAvise soluble in alcohol by the assistance of a gentle heat; and forms the essence of soap, or opodel- doc, AA'hich may be scented at pleasure. * All the soap manufactured in America is made with animal fat. The fat is boiled in a caustic lye, made of vegetable ashes, which con- tain potash, and forms soft soap. Upon adding a solution of sea salt to this, a double elective attraction takes place ; the muiicaic acid of the salt unites to the potash, ann forms muriate of potash, or diges- tive salt of Sylvius, while the soda of the salt unites to the fat, and forms hard soap.—Am. Ed. EFFECTS OF ACIDS ON OILS. 229 Soaps are capable of combining Avith a larger quantity of oil, and rendering it soluble in water. Hence their property of cleansing cloths, linens, &c. They are used as deobstruents in medicine. 4. The fixed oils unite likewise with acids. Messrs. Achard, Comette, and Macquer, have attended to these combinations. Achard gradually adds the concentrated sulphuric acid to the fixed oil; the mixture being tritu- rated, a mass is obtained Avhich is soluble in Avater and in alcohol. The fuming nitric, acid immediately turns the fixed oils black, and sets fire to such as are diving. It is in this case decomposed Avith a rapidity so much the greater, as the oil has a greater affinity Avith the oxi- gene. On this account it is that the inflammation of the drying oils is more easily effected than that of the ethers. Those acids Avhose constituent parts adhere most strongly together, have but a very feeble action on oils; a circumstance which proves that the effect of acids upon oils is principally OAving to the combination of their oxigene. It is by virtue of this strong affinity of oils Avith oxi- gene, that they possess the power of reviving metals. The oxigene then quits the metal, and unites Avith the oils, which become thick and coloured. It likewise fol- lows from hence that drying oils ought to be preferred for this use ; and we find that practice agrees Avith theory in this respect. DIVISION II. Concerning Volatile Oils. Fixed oil is combined with mucilage, volatile oil with the spiritus rector, or aroma; and it is this combina- tion or mixture Avhich constitutes the difference be- tween them. The volatile oils are characterized by a 230 VOLATILE OR ESSENTIAL OILS. strong smell, more or less agreeable; they arc soluble io alcohol, and have a penetrating and acrid taste. All the aromatic plants contain volatile oil, excepting those avIiosc smeii is very transient, such as jessamine, violets, lilies, &c. The volatile oil is sometimes distributed through the Avhole piant, as in the Bohemian angelica; sometimes it exists in the bark, as in cinnamon. Balm, mint, and the greater absinthium, contain their oils in the stem and leaves; elicampane, the iris of Florence, and the caryo- phyllata, in the root. All the resinous trees contain it in their young branches; rosemary, thyme and A\ild thyme, contain their essential oils in their leaves and buds; laven- der, and the rose, in the calyx of their floAA'ers; cimmo- mile, lemon, and orange trees, in the petals. Many fruits contain ii through their whole substance, such as pepper, juniper, &c. Oranges and lemons in the zest and peeling Avhich inclose them. The seed of umbelliferous plants, such as anise and fennel, have the vesicles of essential oil arranged along the projecting lines upon their skin: the nutmeg tree contains its essential oil in the nut itself. —See IS Introduction a V Etude du Ilegne Veg. par M. Buquet, p. 209—212. . The quantity of volatile oil varies according to the state of the plant. Some afford most when green, others when dry ; but the latter constitute the smallest number. The quantity likeAAise varies according to the age of the plant, the soil, the climate, and die time of extraction. The volatile oils likeAvise differ in their consistence. Some are very fluid, as those of lavender, rosemary, and rue; the oils of cinnamon and sassafras are thicker; there are some wiiich constantly preserve their fluidity; others Avhich become concrete by the slightest impression of cold, as those of aniseed and fennel: others again possets the concrete form, such as those of roses, of parsley, and of elicampane. The Aolatiie oils likewise vary in their colour. The oil of rose;- is white; that of it,vender, of a light yellow; that of cinnamon, of a brown ytiicAv; the oil of cammomile is of a fine blue; that of miilefoil, of a sea-green; that of parsley, green, &c. EXTRACTION OF VOLATILE OILS. 231 The weight is likewise different in the different kinds. The oils of our climates are in general light, and swim upon water; others are nearly of the same weight; and others are heavier, such as the oils of sassafras and of cloves. ■ The smells of essential oils vary according to those ol the plants which produce them. The taste of the volatile oils in general is hot; but die taste of the plant does not always influence that of the oil; for example, the oil of pepper has no acrimo- ny, and that which is -obtained from wormwood is not bitter. We are acquainted with tAvo methods of extracting the volatile oils—expression and distillation. 1. Those oils which are, as it were, in a naked state, and contained in projecting and visible receptacles, are obtained by expression. Such are those of citrons, o- ranges, ccdrat, and bergamotte ; the oil issues out of the skin of these fruits Avhen pressed. It may therefore be procured by a strong pressure of the peeling against an. inclined glass. In Provence and in Italy they are rasped; by which means the vesicles are torn, and the oil flows into the vessel destined to receive it: this oil suffers the parenchyma which goes along with it to subside, and be- comes clear by standing. If a lump of sugar'be rubbed against these vesicles, it imbibes the volatile oils; and forms an oleo-saccharum, soluble in Avater, and very proper to give an aromatic fla- vour to certain liquids. 2. Distillation is the method most commonly used in the extraction of volatile oils. For this purpose, the plant or fruit Avhich contains the oil is placed in the boiler or body of the alembic. A quantity of Avater is then pour- ed in, sufficient to cover the plant, and the water is heat- ed to ebullition. The oil AA'hich rises with this degree of heat, comes over Avith the water, and is collected at the surface in a particular receiver, called the Italian receiver, which suilL-rs the surplus of water to escape by a spout issuing from the belly of the vessel,'whose orifice is Ioav- er than that of the neck of the receiver; so that by this means the oil is collected in the neck, without a possibi- lity of its escaping. 232 PROPERTIES OF VOLATILE OILS. The water Avhich passes over in distillation is more or less charged Avith oil, and the odorant principle of the plant, and forms Avhat is known by the name of Distilled Water. These Avaters ought to be returned again into the cucurbit Avhen the same kind of plant is again distilled; because, being saturated Avith oil, and the aromatic prin- ciple, they contribute to augment the ulterior product. When the oil is very fluid or very volatile, it is neces- sary to annex a worm pipe to the alembic, and to have the precaution of keeping the Avater at a very cold tem- perature ; but Avhen, on the contrary, the oil is thick, the Avorm pipe must be removed, and the Avater of the refri- geraicry kept at a moderate temperature. In the first Avay, the oils of balm, mint, sage, lavender, camomile, ike. may be distilled; and, by the second, the oils of roses, of elicampane, of parsley, of fennel, of cumin, &c. The oil of cloves may likeAvise be extracted by distil- lation per descensum, which is determined by applying. the fire above the material. Volatile oils are very subject to be adulterated, either by mixture Avith fat oils, or Avith other essential oils, such as that cf tui-pentine, Avhich is cheaper; or by mixing them Avith alcohol. In the first case the fraud is easily detected—1. By distillation, because volatile oils rise at the heat of boiling Avater. 2. By causing blotting paper to imbibe some of the mixture, and exposing it to a de- gree of heat sufficient to drive off the volatile oil. 3. By- means of alcohol, which becomes turbid and milky by the insolubility of the fixed oil. The volatile oils Avhich have a very strong smell, such as those of thyme and lavender, are often sophisticated by oil of turpentine. In this case the fraud may be disco- ■< vered by soaking a small piece of cotton in the mixture, and leaving it exposed to the air a sufficient time for the smell of the gccd oil to be dissipated, and leave only that of the adulteration. The same end may be ansAArered by rubbing a small quantity of the mixture on the hand, in which the peculiar smell of oil of turpentine is developed. These oils are likeAvise falsified by digesting the plant in oil of olive before distillation. In this manner the oil of camomile is prepared. PROPERTIES OF VOLATILE OILS. 233 The very light oils, such as those of cedrat or berga- motte, are often mixed AAith a small quantity of alcohol. This fraud is easily detected by the addition of a few drops of water, which immediately become Avhite, be- cause the alcohol abandons the oil to unite with the water. The volatile oils are capable of uniting Avith oxigenej with alkalis, and Avith acids. 1. Volatile oils absorb oxigene with greater facility than the fixed oils. They become coloured "by the absorption, grow thicker, and pass to the state of resin; and when they are thickened to this point, they are no longer capa- ble of fermenting, but secure from all putrefaction such bodies as are penetrated and well impregnated with them. On this is founded the theory of embalming.—The ac- tion of acids upon these oils, causes them to pass to the state of resin; and there is no other difference between volatile oil and resin, than that which arises from this ad- dition of oxigene. All the oils, when they assume the character of resin by this combination of oxigene, let fall needle-formed crystals of camphor. Mr. Geoffroy has observed them in the oil of fever feAV, marjoram, and turpentine. Acad, 1721, p. 163. When the oil is changed by the combination of oxU gene, it gradually loses its smell and volatility. To re- store this oil to its original state, it is distilled. A thick matter remains in the distilling vessel, which consists of resin perfectly formed, and is thus separated from the oil, which has not yet undergone the same alteration. 5. ^ The habitudes of acids are not the same with all volatile oils. 1. The concentrated sulphuric acid thick- ens them: but, if it be diluted, it forms savonules. 2. The nitric acid, when concentrated, inflames them; but, when diluted, it causes them gradually to pass to the state of resin. Borrichius appears to have been the first who inflamed oil of turpentine with the sulphuric acid, with* out the nitric acid. Homberg repeated this delicate ex*. periment with the other volatile oils. The inflammation of oils is so much the more easily effected, as the oil is more drying or greedy of oxigene, and the acid more ea- sily decomposed. 3. The muriatic acid reduces oils to Vol. II. Gg 234 starkey's soap, camphor. the saponaceous state, but the oxigenated muriatic' acid thickens them. 3. Starkey appears to have been one of the first who attempted to" combine a volatile oil Avith a fixed alkali. His process is long and complicated, like those of the al- chymists ; and the combination it afforded Avas known by the name of Starkey's Soap. The process of this che- mist Avas so long mere'iy because he used the carbonate of potash, or mild vegetable alkali; but if ten parts of caus- tic alkali, or lapis causticus, be triturated hot Avith eight parts of oil of turpentine, the soap is instantaneously formed, and becomes A-ery hard. This is the process of Mr. Geoffroy.—Acad, des Sciences, ann. 1725. Concerning Camphor. Camphor is obtained from a species of laurel Avhich grows in China and Japan. Some travellers affirm that the old trees contain it so abundantly, that on splitting the trunk it is found in large tears, so pure as to have no need of rectification. To extract the camphor, the roots of the trees are usually chosen ; or, in want of these, all the other parts of the tree. These are put, together Avith water, into an iron alembic, which is covered with its head. The capital is fitted up internally with cords of rice straAv, the joinings are luted, and the distillation pro- ceeded upon. Part of the camphor sublimes, and at- taches itself to the straAv Avithin the head; Avhile another portion is carried into the receiver AAith the water. The Hollanders purify camphor by mixing an ounce of quick- lime with every pound of the substance, and subliming it in large glass vessels.* * Crude camphor is imported by the American merchants from Canton and batavia, where it is bought for fifty and seventy-five cents, and sells in this country, from a dollar, to a dollar and eleven cents a pound. The apparatus necessary for refii.inir this article is simple, does not cost much, and occupies little loom. It consists of a furnace, supporting a sand-bath, glass vessels,and iron,, copper or earthen pans. GAMPHOR. 235: Camphor, thus purified, is a white concrete crystalline substance, of a strong smell and taste, soluble in alcohol, burning with a white flame, and leaving no residue : re- sembling volatile oils in many respects, but differing from I. OF THE CONSTRUCTION OF THE FURNACE. A furnace sufficiently large for one active and industrious man to attend, will occupy the space of eight feet nine inches m lengu,. and two feet six .nches in breadth, it must be made oi se'.ei. cast !ron plates, half an inch thick, thirty inches long, and ntteen broad. These plates are to be placed upon eight piles of bricks, parallel to each other, and nine inches apart. The bricks are to be ten inches higii. thirty long, and six broad. Great care must be taken, that the lower sides of the plates meet each other exactly midway on the upper side of the bricks, which should be well covered, with a thick bed of mortar. Bricks serve to confine the sand. When the furnace is connected with a wall, there is no occasion for more than a single row of them : and to ob- tain a considerable draught of air, a chimney should be carried horn the fourth plate with an aperture four inches in diameter, and the flues of the third and fifth plate, may communicate with this chim- ney. Two separate flues may be carried from the second and sixth plates, and the first and seventh should enter the second and sixth. The chimney, if convenient, may be made to enter into that pf the house, but if not, it should be about fifteen feet high. II. OF THE GLASS VESSELS. The vessels are procured at a glass-house, and are made of green glass. They should be blown as thin as an oil flask. They are of a circular form, shaped flat like a turnip, and have a neck bom one to three inches high, with an aperture, from half an inch to one inch in diameter. Their bottoms should be eleven inches broad, and the top ought to be four inches from the bottom. They cost twenty-five dollars a hundred in Philadelphia. III. OF THE PANS. Fourteen pans may be made of iron, copper or earth. Sheet iron is the best material They should he round, one foot in diameter, with a rim pecked on four inches and a half high, and ought to have two small handles. They cost one dollar a-piece in this city. Having prepared this necessary apparatus, the next thing is to make use of it, in such a manner as to refine the camphor. Having taken the article out of the tubs, the glass vessels are to be filled two-thirds full of it, and the apertures in the neck*, slightly- stopped, with paper or cotton plugs. They are then to be placed on $36 CAMPHOR. them in certain properties; such as that of burning without a residue ; of dissolving quietly, Avithout decomposition or alteration, in acids*; and of being volatilized by a gentle heat, Avithout change of its nature. Camphor is obtained by distillation from the roots of zedoary, thyme, rosemary, sage, the inula helenium, the the bottom of the pans, and covered near to the base of their necks with sand The pans, holding the vessels containing the camphor, are to be carried to the sand-bath, and surrounded near to the top of the rin» with sand. A gentle fire is to be kindled in the furnace, at four o'clock in the morning, and gradually increased, until the camphor melts, which it does when it arrives at 304° of Fahrenheit's thermometer. It will first rise in flowers, which will dissolve and run down the sides of the vessel. When it has melted, or is boiling, the glass is to be ele- vated in such a manner that the hot sand, may reach only to the mid- dle of its belly, in order that the cool aw may be admitted to the up- per surface of the glass, to congeal the camphor as it sublimes. Having kept it in a liquid or boiling state, from eight to ten hours, the refined camphor will be found, adhering to the upper side of the vessel, and is to be taken from it by breaking the glass while hot, or it may be kept until cool and then broken. The glass is easily separated from it, by means of a knife. The foul parts wh.ch adhere to the bottom of the glass, and which cannot be easily parted from it, are to be broken into pieces, and sublimed a second time, with an additional supply of camphor. When the crude camphor is of a white colour, or contains little foreign matter, no addition is to be made to it; but when it is brown or black, one ounce of slacked or quick lime, is to be mixed with every three or four pounds of it. The utility of lime in this opera- tion is noticed by Margraff. One man can refine and pack up, from eighteen to twenty-five pounds every day. If any of the glass vessels holding the melted camphor should crack, which sometimes happens, and which is discovered, by the flowers rising into the air from their sides and tops, the pans con- taining it are to be immediately removed to a cool place ; and if the camphor is found mixed with the sand, the whole is to be put into other vessels, and the operation conducted as before. The loss in refining one hundred wei ht of this article cannot be accurately ascertained, as it depends upon the purity of the crude material, and the care in conducting the process. It cannot be very great. Professor Robertson, in a note to Dr. Black's Chemistry informs us, that in a manufactory in Holland, he saw more than one hun- dred vessels in a furnace at one time, and that there was but a mo- derate smell of camphor in the room.—Am. Ed. ROPERTIES OF CAMPHOR. ' 23tT juiemony, the pasque floAver or pulsatilla, &c. And it is to be observed, that all these plants afford a much greater quantity of camphor when the sap has been suffered to pass to the concrete state, by a desiccation of several months. Thyme and pepper mint, sloAvly dried, afford much camphor; whereas the fresh plants afford volatile oil: most of the volatile oils, in passing to the state of resin, also let fall much camphor. Mr. Achard has like- wise observed that a smell of camphor was disengaged when he treated the volatile oil of fennel with acids. The combination of the diluted nitric acid Avith the volatile oil of anise, afforded him a large quantity of crystals, which possessed most of the properties of camphor. He ob- tained a similar precipitate by pouring the vegetable alkali Upon vinegar saturated with the volatile oil of angelica. From all these facts it appears, that the base of cam ■ phor forms one of the constituent principles of some vo- latile oils; but it is in the liquid state, and does not be- come concrete but by combining with oxigene.* Camphor is capable of crystallization, according to Mr. Romieu, whether in sublimation, or Avhen it is sloAvly precipitated from alcohol, or Avhen alcohol is supersaturated with it; it precipitates in slender filaments, crystallizes in hexagonal blades attached to a common axis, and it sublimes in hexagonal pyramids or in poly- gonal crystals. Camphor is not soluble in water; but it communi- cates its smell to that fluid, and burns on its surface. Romieu has observed that small pieces of camphor, of one-third or one-fourth of a line in diameter, being placed on die surface of pure Avater in a glass, have a ro- tatory motion: and this appears to be an electrical phae- nomenon; for the motion ceases if the water be touched with a conducting substance; but continues if it be * Camphor may be formed artificially, by passing a current of mu- riatic acid gas, through the spirit of turpentine. When made in this manner it differs from the Laurel Camphor in its taste, which is not so bitter; in its odour, which is not so penetrating, and in the effect produced upon it by the nitric and acetic acids, the first of which dissolves it by a reciprocal decomposition; the latter not at all j while both dissolve camphor rapidly.—Am Ed. 238 PROPERTIES OF CAMPHOR. touched Avith an insulating body, such as glass, sulphur, or resin. Bergen has observed that camphor does not turn upon hot Avater. Acids dissolve camphor Avithout producing any altera- tion in it, or becoming themselves decomposed : the nitric acid dissolves it quietly; and this solution has been called Oil of Camphor. Camphor precipitated from its solu- tion in acids by the addition of alkalis, is heavier, harder and much less combustible, according to the experi- ments of Mr. Kosegarten. By distilling the nitric acid several times from this substance, it acquires all the pro- perties of an acid Avhich crystallizes in parallelopipedons. To obtain the camphoric acid, nothing more is required than to distil the acid at several times from the camphor, and in a large quantity. Mr. Kosegarten distilled the ni- tric acid eight times from camphor, and obtained a salt crystallized in parallelopipedons, which reddened syrup of violets, and the tincture of turnsole. Its taste is bitter; and it differs from the oxalic acid in not precipitating lime from the muriatic acid. With potash it forms a salt which crystallizes in regu- lar hexagons. With soda it affords irregular crystals. With ammoniac it forms crystalline masses, which ex- hibit crystals in needles and in prisma. With magnesia it produces a white pulverulent salt, which may again be dissolved in water. It dissolves copper, iron, bismuth, zinc, arsenic, and cobalt. The solution of iron affords a yellowish Avhite poAvder, which is insoluble. This acid forms, with manganese, crystals whose planes are parallel, and in some respects resemble basaltes. The camphoric acid, or rather the radical of this acid, exists in several vegetables; since camphor may be extracted from the oils of thyme, of'cinnamon, of tur- pentine, of mint, of feA-erfeAv, of Sassafras, &c. Mr. Dehne has obtained it from the pasque flower or Pulsatil- la ; and Cartheuser has indicated several other plants Avhich contain it. Alcohol readily dissolves it, and it may' be precipi- tated by water alone; this solution is known in phar^ USES OF CAMPHOR. 239 macy by the name of Camphorated Spirit of Wine, or Camphorated Brandy, Avhen brandy is the sol- vent. The fixed and volatile oils likeAvise dissolve each other by the assistance of heat; the solutions let fall crystals in vegetation, similar to those Avhich are form- ed in the solutions of sal-ammoniac, composed of very- fine filaments adhering to a middle part. This obser- vation Avas made by Mr. Romieu. Acad, des Sciences, 1756. Camphor is one of the best remedies which the art of medicine possesses. When applied to inflammatory tu- mours, it is resolvent; and, internally taken, it is antis- pasmodic, especially when dissolved in brandy. It is given in Germany and in England in the dose of several drams per day; but in France our timid physicians do not prescribe it in a larger dose than a few grains. It mitigates heat in the urinary passage. It is given tritu- rated with yolk of egg, sugar, &c. It has likewise been supposed that its smell destroyed or drove away moths? and other insects which feed upon eloth, &c. ARTICLE III. Concerning Resins. The name of Resin is used to denote inflammable sub- stances soluble in alcohol, usually affording much soot by their combustion.; they are likewise soluble in oils but not all in water. All the resins appear to be nothing else but oils rendered concrete by their combination with oxigene. The exposure of these to the open air, and the decom- position of acids applied to them, evidently prove this conclusion. Resins in general are less sAveet than the balsams. They afford more volatile oil, but no acid, by distil- lation. 240 VARIOUS RESINOUS SUBSTANCES. There are some among the knoAVn resins which are very pure, and perfectly soluble in alcohol, such as the balm of Mecca and of Copahu, turpentines, tacamahaca, elemi: others are less pure, and contain a small portion of extract, AA'hich renders them not totally soluble in alco- hoi; such are mastic, sandarach, guaiacum, labdanum, and dragon's blood. 1. The balsam of Mecca is a fluid juice Avhich becomes thick and broAvn by age. It Aoavs from incisions made in the amyris opobalsamum. It is known by the different names of Balm of Judea, of Egypt, of Grand Cairo, of Syria, of Constantino- ple, &c. Its smell is strong, and inclining to that of lemons; it* taste is bitter and aromatic. This balsam, distilled by the heat of boiling water, af- fords much volatile oil. It is balsamic; and is given incorporated with sugar, or mixed with the yolk of egg. It is aromatic, vulnera- ry, and healing. 2. The balsam of Copahu flows from a tree called Co- paiba, in South America, near Tolu. It affords the same products, and possesses the same virtues, as the foregoing. 3. The turpentine of Chios flows from the turpentine tree, which affords the pistachios. It is fluid, and of a yelloAvish Avhite 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. Incisions are made first at the loAver parts of the tree, and afterwards by de- grees higher up. This turpentine distilled on the water-bath, Avithout addition, affords a very white, very limpid, and very fragrant volatile oil: a more ponderous oil may be extracted at the heat of boiling water; and the resi- due, which is called Boiled Turpentine, affords by distillation, in the reverberatory furnace a weak acid, a small quantity of broAvn consistent oil, and much coal. The turpentine of Chios is very rare in commerce. Venice turpentine is extracted from the larix : its colour VARIOUS RESINOUS SUBSTANCES. 241' is a bright yelloAv, its consistence limpid, its smell strong and aromatic, and its taste bitter. The tree which affords it is that which affords manna. Holes are bored during the summer near the bottom of the trunks of these trees, into which small gutters or tubes are inserted, to convey the juice into vessels intended to receive it. The resin is obtained only from trees in full vigour; the old trees very often have considerable depo- sitions of resin in their trunks. This turpentine affords die same principles as that of Chios. It is used in medicine as a detergent for ulcers in the lungs, kidneys, &c. either incorporated Avith sugar, or mixed Avith the yolk of an egg, to render it more misci- ble Avith aqueous potions. The soap of Starkey, which we have spoken of under the article of Volatile Oils, is made with this turpentine. The resin known in commerce by the name of Strasburgh Turpentine, is a resinous juice of the con- sistence of a fixed oil, of a yellowish Avhite colour, a bit- ter taste, and a more agreeable smell than the preceding resins. It flows from the yew-leaved fir, which is very com- mon in the mountains of SAvitzerland. This resin is collected in blisters, which appear beneath the bark in the strong heats of summer. The peasants pierce these ve- sicles Avith the point of a small horn, which becomes filled with the juice, and is from time to time emptied into a larger vessel. The balm of Canada differs from the turpentine of the fir in its smell only, which is more pleasant. It is obtained from a species of fir which grows in Ca- nada. Oil of turpentine is more particularly used in the arts. It is the great solvent for all resins; and, as it evaporates, it leaves them applied to the surface of bodies on which the mixture has been spread. As resins are the basis of all varnishes, alcohol and oil of turpentine must be the ve- hicles or solvents. 4. Pitch is a resinous juice, of a yellow colour, more or less inclining to brown. It is afforded by a fir Vol. II. Hh 242 VARIOUS RESINOUS SUBSTANCES. named Picea or Epicea. Incisions are made through the bark; and the wound is rcneAved from time to time, as the lips become cailous. A vigorous tree often alibi ds forty pounds. Pitch melted, and expressed through bags of cloth, is rendered purer. It is packed in ban els, by the name of White Pitch, or Burgundy Pitch. White pitch mixed Avith lampblack, forms black pitch. White pitch kept in fusion becomes dry. The desicca- tion may be facilitated Avith vinegar, and leaving it for a time over the fire. It then becomes very dry, and is cal- led Colophony. Lampblack is the soot of burned pitch. It is likewise prepared by collecting die soot of pit-coal. 5. Galipot is a concrete resinous juice, of a yellowish white colour and strong smell. This juice comes from Guienne, AAhere it is afforded by two species of pine, the pinus maritima major, et minor. When these trees have acquired a certain size, a hole or notch is cut through the bark, near the bottom of the trunk. The resin issues out, and Aoavs into ves- sels placed beneath to receive it. Care is taken to keep the Avound open, and to renew it. The resin flows during the summer; but that Avhich issues out during the spring, autumn, and a\ inter, dries against the tree. The pine likeAvise affords tar, and the oil called huile de Cade. For this purpose the wood of the trunk, bran- ches, and roots, is heaped together, and covered with turf, over Avliich a fire is lighted, as if to convert them into charcoal. The oil which is disengaged, not being at li- berty to escape, falls to the bottom into a channel or gut- ter, a\ hich conveys it into a tub. The most fluid part is sold under the name of huile de Cade; and the thicker part is the tar used for paying or painting the parts of shipping and other vessels. The combination of several resins, coloured by cin- nabar and minium, forms sealing-Avax. To make the wax, take half an ounce of gum lac, two drams of turpentine, the same quantity of colophony, one dram of cinnabar, and die same quantity of minium. The VARIOUS RESINOUS SUBSTANCES. Z43 lac and the colophony are to be first fused, after Avhich the turpentine is to be added, and lastly the colouring matters. . 6. Mastic has the form of white tears of a farinaceous appearance, having little smell, and a bitter astringent taste. Mastic flows naturally from the tree, but its pro- duce is accelerated by incisions. The lesser turpentine tree, and the lentiscus, afford that which is met with m commerce. Mastic affords no volatile oil Avhen distilled Avith water. It is almost totally soluble in alcohol. This resin is used in fumigations. It is chewed to strengthen the gums; and it forms the basis of several drying varnishes. 7. Sandarach is a concrete resinous juice, in dry Avhite transparent tears, of a bitter and astringent taste. It is obtained from most species of the juniper, and is fouud betAveen the bark and the wood. Sandarach is almost totally soluble in alcohol, Avith which it forms a very white varnish, that dries speedily. For this reason, the resin itself is known by us under the name of Varnish (vernis.J 1. Labdanum is a black resinous juice, dry and friable, of a strong smell, and a disagreeable aromatic taste. It transudes from the leaves and branches of a kind of cistus, which groAvs in the island of Candia. Tournefort, in his Voyage to the Levant, informs us that when the air is dry, and the resin issues out of the pores of the cistus, the peasants strike all the parts of these trees Avith a kind of whip, made of several thongs of leather, fixed to the end of a staff. 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 Avith a very fine ferruginous sand, for the purpose of increasing its weight. 9. Dragon's blood is a resin of a deep red in the mass, but brighter Avhen in powder. It has neither taste nor smell. It is obtained from the drakena, in the Canary islands, from which it flows in tears during the dog-days. It is also obtained from the ptero-carpus draco. The parts are exposed to the vapour of hot-water; the juice issues 244 VARIETIES OF BENZOIN. out in drops, which are collected and wrapped up in the leaves of reeds. The dragon's blood of the shops, which has the form of flattened orbicular loaves, is a composition of various gums, to which this form is given, after they have been coloured Avith a small quantity of dragon's blood. Dragon's blood is soluble in alcohol: the solution is red : the resin itself may be precipitated of the same colour. This resin is used in medicine as an astringent. ARTICLE IV. Concerning Balsams. Some authors define balsams to be fluid inflamma- ble substances; but there are some which are dry. Others again give this name to the most fragrant among the resins. M. Bucquet has confined this denomination to such resins only as have a sweet flavour, capable of being communicated to water; and which more especially contain fragrant acid and concrete salts, Avhich may be se- parated by decoction or sublimation. It appears there- fore that these substances contain a principle not found in resins, which combining with oxigene, forms an acid; while the oil, saturated with the same air, forms the resin. This acid salt is soluble in Avater and alcohol. As the chemical analysis points out a sufficiently striking differ- ence betAveen balsams and resins, Ave think it proper to treat them separately. The substances called Balsams are therefore resins united with a concrete acid salt. We are acquainted with three principal kinds; viz. benzoin, the balsam of Tolu, and the storax calamita. 1. Benzoin is a coagulated juice, of a pleasant fragrant smell, Avhich becomes stronger by friction and heat. Two varieties of this substance are known; the ben- z»e amygdaloides, and the common benzoin. The first VARIETIES OF BENZOIN. 245 is composed of the most beautiful tears of this balsam, connected together by a gluten of the same nature, but browner, and of the" aspect cf nutmegs in its fracture. The second is merely the juice itself, without any mixture of these fine and very pure tears. It comes to us from the kingdom of Siam," and the island of Sumatra; but we do not knoAV the tree that affords it.* Benzoin, laid upon hot coals, fuses, speedily takes fire, and emits a strong aromatic smell. But if it be merely heated, Avithout setting it on fire, it sAvells up, and emits a more pleasant though less powerful smell. Benzoin pounded, and boiled in Avater, affords an acid salt, which crystallizes in long needles by cooling. This salt may also be extracted by sublimation. It rises by a degree of heat even less than that Avhich is required to raise the oil of benzoin ; and this is the substance called Flowers of Benzoin, or the Sublimed Acid of Benzoin. Neither of these processes are economical; and in the preparation of these articles, in the large Avay, I begin by distilling the benzoin, and cause all the products to pass confounded together into a capacious receiver. I then boil the product in water, and by this means I obtain a much greater quantity of the salt of benzoin: because, in diis state, the water attacks and dissolves the Avhole contents; whereas the most accurate trituration will not produce the same effect. The sublimed acid of benzoin has a very penetrating aromatic smell, which excites coughing; more especially if the subliming vessels be opened while yet hot. It red- dens the syrup of violets, and effervesces with the alka- line carbonates. It unites with earths, alkalis and metals, and forms benzoates, of which Bergmann and Scheele have given us some account.f * For a drawing and description of this tree, consult Dryander, in the Phil. Trans, vol. Ixxvii. No. 31. t Benzoic acid exists in the urine of horses.—These animals are said to be diseased when they secrete it—for a sound horse gives lit- tle or none. It does not arise from their food, for it cannot be de- tected in straw or oats. Sometimes it is combined with soda.*— Am F.d. * Tilloch'f Philos. Mag. vol. xvi., p. \$\. 246 BALSAM OF TOLU. Alcohol dissolves benzoin totally, Avithout leaving any residue but such foreign impurities as the balsam m«;y happen to contain. Itrm.v be precipitated by the addition of water ; and then constitutes the opaque fluid called Lac Virginale. Benzoin is used as an aromatic in medicine: but it is seldom used in substance, because of its sparing solubi- lity : its tincture, and volatile acid, are used. The latter is a good incisive medicine to be administered in pituitous obstructions of the lungs, the kidneys, &c. It is given in extracts, or dissolved in water. Benzoin is employed in fumigations for indolent tu- mours. The oil is likeAvise an excellent resolvent. It is applied by friction to members affected Avith cold rheuma- tic and paralytic disorders. 2. The balsam of Tolu, of Peru, or of Carthagena, has a mild and pleasant smell. It is met with in commerce in tAVO different forms ; ei- ther in shells, or in the fluid state. The cocoa is softened by boiling water, and the balsam Aoavs out in the fluid form. The tree Avhich affords it, is the Toluifera of Linnae- us. It grows in South America, in the district called To- lu, between Carthagena and Nombre de Dios. The fluid balsam affords much volatile oil Avhen distil- led by the heat of boiling Avater. An acid salt may be extracted from this balsam, Avhich greatly resembles that of benzoin, and may be obtained by the same processes; but this sublimed salt is com- monly broAvn, because it is soikd by a portion of the bal- sam, Avhich rises Avith a less heat than benzoin does. This balsam is soluble in alcohol, and may be precipi- tated by the addition of water. It is much used in medicine, as an aromatic, vulnerary, and antiputrescent remedy.' It is administered either tri- turated Avith sugar, or mixed Avith some extract. A sy- rup is prepared from it by digesting it in a gentle heat with sugar; or by dissolving it in alcohol, adding sugar, and suffering the alcohol to dissipate spontaneousiv. It is falsified by macerating the distilled oil of "benzoin upon the buds of the balm scented poplar, and adding a small quantity of the natural balsam. STORAX, OR STYRAX. 247 Storax or styrax calamita is a juice of a very strong but pleasant smell. Two varieties are known in com- merce : the one in reddish clean tears ; the other in mas- ses of a blackish red colour, soft and fatty. The plant Avhich affords it is called the oriental liquid amber. It has been long supposed to be the styrax folio mali cotonsei C. B. which is knoAvn in Provence, in the wood of La Chatreuse de Montrieu, by the name of Ali- bousier; and, according to Duhamel, affords a very odo- rant juice, which he took for storax. Its habitudes during analysis are the same as the pre- ceding, and it exhibits the same phenomena. It was formerly brought to us in canes or reeds, whence its name of storax calamita. , These three balsams form the base of those fragrant * pastils which are burned in the chambers of the sick, to conceal or disguise bad smells. These balsams are made into masses by means of gum ; with the addition of char- eoal and the nitrate of potash, to facilitate combustion. ARTICLE V. Concerning Gum Resins. The gum resins are a natural mixture of extract and resin. They seldom flow naturally from plants, but issue out from incisions made for that purpose. They are some- times white, as in the tithymalus and the fig-tree; some- times yellow, as in the cheiidohium: so that we may consider these substances as true emulsions, Avhose con- stituent principles vary in their proportions. The gum resins are partly soluble in water, and partly in alcohol. One character of gum resins is, that they render water turbid in which they are boiled. This class is sufficiently numerous: but we shall only treat of the principal species, and more especially tiiose Which are used in medicine. - 1. O'ibanum, or frankincense, is a gum resin, in tears of a yelloAvish white colour and transparent. Tavo kinds 248 SCAMMONV. GUM CUTT/E. are knoAvn in trade : the male incense, in small very pure tears ; and the female incense, in large and impure tears. The tree which affords it is not knoAvn. Some authors suppose it to be the cedar with cypress leaves. Oiibanum contains three parts of resinous matter, and one of extract. When it is boiled in Avater, the solution is Avhite and turbid, like that of all the juices of this class. When it is fresh, it affords a quantity of volatile oil. Oiibanum is used in medicine as a resolvent. But its chief use is in our temples, where it has been adopted as one of the instruments of worship of the Divinity. It is used in hospitals, to disguise the smell of the pu- trid air Avhich is exhaled. M. Achard has proved that this proceeding has no other effect than that of deceiving the sense of smelling. 2. Scammony is of a blackish grey colour, a bitter and acrid taste, and a strong nauseous smell. Tavo varieties are met with in commerce; one of which comes from Aleppo, and the other from Smyrna. The first is paler, lighter, and more pure ; the second is black, heavy, and mixed with foreign substances. It is extracted from the convolvulus scammonia, prin- cipally from the root. For this purpose incisions are made at the head of the root. It is collected in muscle shells. But most of that met with in trade is obtained from the roots by expression. From the results of the analysis of Geoffroy and Car- theuser, it appears that the proportion of the component parts varies in die different specimens examined. The latter obtained near one half of extract, whereas the for- mer only one sixth. Scammony is used in medicine as a purgative, in the dose of several grains. When triturated with sugar and almonds, it forms a very agreeable purgative emulsion. When softened by a mixture of the juice of liquorice, or of Avild quinces, it forms the diagre- dium. 3. Gum guttae has a reddish yclloAv colour: it has no smell, but its taste is acrid and caustic. Gum gunse AA'as brought to Clusius in 1630. It comes from the kingdom of Siam, from China^ and from the island of CONCERNING ALOES. 249 Ceylon, in cylinders of various sizes. The tree which affords it is called Coddam Pulli. Herman reports, from his oAvn observation as an eye Avitness, that a milky and yellowish juice flows from incisions made in these trees; that this juice becomes thick by the heat of the sun; and that, when it is in a state fit to,be handled, it is formed into large globular masses. Geoffroy has extracted five sixths of resin from gum guttas. Cartheuser has ascribed to it more extractive than resinous matter. Gum guttae is sometimes used as a purgative, in a dose of a feAv grains. But the principal use of this substance is in painting, where it is recommended by the beauty of its colour. 4. Asa fcetida is met with in tears of a yellowish Avhite colour; but most commonly in the form of loaves formed by the aggregation of a number of the tears. It has an acrid and bitter taste, and its smell is one of the most disagreeable. The plant Avhich affords it is called Ferula Asa Fcetida. This plant grows in Persia: and the juice of its root is obtained by expression, according to Kaempfer. It is fluid and white when it issues from the plant, and it emits an abominable smell when recent. This juice loses its smell, and becomes coloured, as it dries. But it still preserves smell enough to entide it to the name of Stercus Diaboli. The Indians find its flavour agreeable; they use it for seasoning, and call it the food of the gods: a proof which evinces, beyond every argument, that tastes must not be disputed. , Cartheuser found it to contain one third of resin. . It is a solvent and discutient remedy; and more ' particularly valuable as a most powerful antihysteric. 5. Aloes is a juice of a red broAvn colour, and very considerable bitterness. Three species are distinguished —the soccotrine aloes, the hepatic aloes, and the coballine aloes; they differ only in their degree of purity. M. de Jussieu, Avho saw these three varieties prepared at Mor- viedro in Spain, assures us that they are all obtained from Vol. II. I i 250 ELASTIC GUM. the aloe vulgaris. The first variety is obtained by making incisions in the leaves. Time is alloAved for its impurities to subside perfectly. The fluid is then de- canted from the dregs, and left to become thick; after Avhich it is put into leathern sacks for sale, under the name of Soccotrine aloes. A juice of the same nature is ob- tained by expression from the same leaves Avhich Avhen clarified in the same manner, forms the hepatic aloes: and the coballine aloes is obtained by a stronger pressure. The Soccotrine aloes contains no more than one eighth of resin, according to Boulduc. The hepatic aloes con- tains half its Aveight. Aloes is very much used in medicine as a purgati\re, tonic, alterative, and vermifuge. 6. Gum ammoniac is sometimes met with in small tears, white Avithin, and yellow Avithout. But they are of'en united in the mass, resembling the benzoe amyg- daloides. Its smell is fetid; and its taste acrid, bitter, and rather nauseous. This juice comes from the deserts of Africa, and the plant which affords it is unknoAvn: it is presumed to be of the class of umbelliferous plants, from the figure of the seeds found in it. Gum ammoniac is very much used in medicine. It is a Atry good alterative; and is given in pills, incorporated with sugar, or in some extract. It may even be dissolv- ed or diffused in water; this liquid becomes turbid, and of a yellowish Avhite. Gum ammoniac enters into the composition of all discussive plasters. Concerning Caoutchouc, or Elastic Gum. Elastic gum is one of those substances AA'hich it is difficult to class. It burns like resins; but its softness, its elasticity, and its insolubility in the menstruums Avhich usually dissolve resins, do not alloAv us to class it among those bodies. The tree which affords it is known by the name of Seringa by the Indians of Para. The inhabitants of the province of Esmeraldas, a province of Quito, call ELASTIC GUM. 251 it Hhava; and those of the province of Mainas Caout- chouc. Mr. Richard has proved that this tree is of the family of the euphorbia; and Mr. Dorthes has observed, that the coccus Avhich are covered Avith a doAvn that resembles small straws, Avere covered Avith a gum very much resembling the elastic gum. These insects feed on the euphorbium; but those which come from other situati- ons afford the same juice. We are indebted to Mr. Condamine for an account, and accurate details, concerning this tree. (Acad, des Sciences, 1751.) This academician informs us, after M. Fresneau, engineer at Cayenne, that the caoutchouc is a very lofty tree. Incisions are made in the bark; and the Avhite juice, which flows out in a more or less liquid state, is received in a vessel placed for that pur- pose. This is applied in successive coatings upon a mould of clay, and dried by the fire, or in the sun.* All sorts of designs are traced upon it while soft; and Avhen it is dry, the clay mould is crushed, and the pieces shaken out.f This gum is very elastic, and capable of great exten- sion. When elastic gum is exposed to the fire, it be- comes soft, swells up, and burns Avith a white flame. It is used for illumination, instead of candles at Cav- enne. It is not at all soluble either in water or alcohol. But Macquer has assured us that ether is its true solvent; and upon this property he has instituted the art of making * It is said that twenty seven coats of the milk are applied to the mould. t Many trees, natives of the torrid zone, yield a milky juice, of the same nature as the Caoutchouc, as Artocarpus integril'oiia or common jack tree ; Ficus indica et religiosus; Hippomane biglan- dia, and Cecropia peltata. The editor has examined a great variety of the milky plants of the United- States, and extracted gum elastic from many of them, as Apocynum Cannabinum or Indian Hemp, Sonchus i loridanus» or Sow Thistle, Asclepias Syriaca, or Syrian Swallow wort, Euphorbia Picta or Painted Spunge, 8cc.—4m. Ed. 252 ELASTIC GUM. bougies for chirurgical uses of clastic gum, by applying this solution upon a mould of a\ ax till it is of the requi- site thickness.* Mr. Berniard, to whom we are indebted for import- * The liquid of Gum elastic is drawn from a tree by incisions, and thickens in the manner of resinous juices. It cannot be pro- cured in its original slate of fluidity, to give it all the the forms un- der which it might be useful to us. It grows in Brazil, and the ne- cessity of parting the line, is an obstacle to the juice arriving in a proper state for our purposes, as it is decomposed by heat, in the same manner as milk, exhaling a very foetid odor, and having no lon- ger its original properties. Sir Joseph Banks, President of the Royal Society of London, once had a bottle of it in its original state, but which after a little time became decomposed, since which he has not been able to procure any more from Lisbon, although he has offered fifty guineas for a second bottle Tubes of gum elastic are made by cutting a bottle circularly in a spiral slip of a few lines in breadth. It is an easy matter to cut a a bottle in such a manner, as to form a single long slip. The whole srip is then to be plunged into ether, until it is suffi- ciently softened, which it will be in half an hour. Mr. Grossart, the the author of an excellent memoir on the method of making instru- ments of Gum clastic, says that there is a great diversity in the man- ner, in which different sorts of vitriolic ether act, and of which the cause is not known. The ether should be well washed in water, and contain no vitriolic acid. The slip being taken out one. of the extremities is to be taken hold of, and rolled first upon itself at the bottom of the tube, pressing it; then the rolling is to be continued, mounting spirally along the mould, and taking care to lay over and compress with the hand every edge, one against the other, so that there may not be any vacant space, and that all the edges may join exactly. The whole is then to be bound hard Avith a tape an inch wide, taking care to turn it the same Avay with the slip of elastic gum. This tape is to be tied over with pack-thread, so that by every turn of the pack-thread, joining ano- ther, an equal pressure is given to every part: it is then left to dry, and the tube is made. ,, It is easy to draw off the tube ; if it sticks, it may be plunged in hot water. Tubes may likewise be made with the oil of turpentine and lavender. He likewise tells us, that he has made the tubes by boiling the gum elastic in water. When water is used, after the tube is co- vered with packthread, it is to be kept some hours in boiling water Always avoid placing the exterior slips one upon another.—Am. Ed* * Repertory of Arts, vol, 1. ELASTIC GUM. 253 ant observations upon this substance, found only the nitric ether to dissolve elastic gum. Very pure sulphu- ric ether did not perceptibly act upon it. . If elastic gum be put in contact Avith a volatile oil, such as that of turpentine, or even if it be exposed to the vapour of that fluid, it SAvells, softens, and becomes very pasty. It may then be spread upon paper, or ap- plied as a varnish to cloth; but this covering preserves its adhesive quality, and does not lose it for a long time. The mixture of volatile oil and alcohol forms a better solvent than the pure oil, and the varnish dries more speedily. Mr. Berniard has concluded from his experiments that the elastic gum, is a fat oil coloured by a matter so- luble in alcohol, and soiled by the smoke to which the gum is exposed in drying. If linseed oil be rendered very drying by digesting it upon the oxides of lead, and it be afterwards applied with a small brush upon any surface, and dried by the sun or in the smoke, it affords a pellicle of a consider- able degree of firmness, evidently transparent, burn- ing like the elastic gum, and Avonderfully elastic and extensible. If this very drying oil be left in a Avide shallow vessel, the surface becomes thick, and forms a membrane Avhich has the greatest analogy Avith the elastic gum. A pound of this oil spread upon a stone, and exposed to the air for six or seven months, acquired almost all the properties of elastic gum. It was used to make catheters and bougies; Avas applied to varnish bal- loons, &c Some gum resins are cleared by art of their extrac- tive principle, for the purpose of applying them to vari- ous uses. Such is the intention of the process used to make bird-lime. This is made from different substan- ces, as the berries of misletoe, the fruit of the sebesten, &c. But the best is made of the hollyoak. These trees are peeled in the month of June or July: the outer bark is rejected, and the second is boiled in spring Avater for seven or eight hours. It is then made into masses, Avhieh are buried in the ground, and covered with stones, for several layers one over the other. After having pre- viously drained off the moisture, diey are suffered to fer- "254 VAKNISH OF THE CHINESE. ment for fifteen days, until the matter has acquired the adhesive consistence of paste. The mass is then beaten till it becomes capable of being wrought Avith the hands, or kneaded; after Avhich it is Avashed in a running stream. Lastly, it is placed for three or four days in another vessel, that it may throw up its skum or impuri. ties ; in Avhich last state it is put into proper vessels, and kept for use. The following composition is likewise made use of under the name of bird-lime. > Take one pound of bird- lime, one pound of goose-grease; add to this one ounce of vinegar, half an ounce of oil, and the same quantity of turpentine. Boil the mixture for several minutes, and heat the mass Avhen you are desirous of using it as a ce- ment. It may be prevented from freezing in winter, by adding a small quantity of petroleum. Concerning Varnish. The Pere d'Incarville has informed us that the tree Avhich affords the varnish of China is called Tsi-chou by the Chinese. This tree is propagated by offsets. When the cultivator is desirous of planting this, he takes a branch, which he Avraps up in a mass of earth, by means of flax. Care is taken to moisten this earth; the branch pushes out roots, and is then pruned and transplanted. This tree groAVS to the size of a man's leg. This varnish is draAvn in spring. If it be a cultivated tree, it affords three gatherings. It is extracted by inci- sions made in the spring; and Avhen the varnish, which is received, in shells, does not Aoav, several hog's bristles, moistened with Avater or spittle, are introduced into the Avound, and cause it to run. When the tree is exhaust- ed, the upper part of it is wrapped in straw, which is set on fire, and causes the varnish to precipitate to the bottom of the tree, where it Aoavs out of perforations made for that purpose. Those avIio collect the varnish set out before day-break, and place their shells beneath the apertures. The shells are not left longer than three hours in their place, because the heat of the sun Avould evaporate the varnish. ART Of VARNISHING* 255 The varnish emits a smell which the workmen are very careful to avoid respiring. It produces an effect Avhich they call the bud of the varnish. When the varnish issues from the tree, it resembles pitch. By exposure to the air it naturally becomes co- loured, and is at last of a beautiful black. The juice AATiichnoAVsfrom incisions made in the trunk and branches of the rhus toxicodendron, possesses the same properties. The tree that grows in our climates affords a white milky fluid, which becomes black and thick by the contact of the air; its colour is the most beautiful black: and it would be easy to introduce this valuable species of industry into the kingdom, because the tree groAvs won- derfully well in all climates, and resists the cold of the winter. To make the varnish 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 Chinese use the oil of tea, which they render dry- ing by boiling it Avith orpiment, realgar, and arsenic. The varnishes most used in the arts have all of them the resins for their base; and the fundamental facts in this valuable art are reducible to the following principles/ To varnish any substance, consists in applying upon its surface a covering of such a nature, as shall defend it from the influence of the air, and give it a shining ap- pearance. A coat of varnish ought therefore to possess the folioav- ing properties:—1. It must exclude the action of air; because wood and metals are varnished to defend them from decay and rust. 2. It must resist water; for other- wise the effect of the varnish could not be permanent. 3. It ought not to alter such colours as are intended to be preserved by this means. It is necessary therefore that a varnish should be easily extended or spread over the surface, without leaving pores or cavities; that it should not crack or scale ; and that it should resist water. Now resins are the only bodies that possess these properties. Resins consequently must be used as the bases of var- nish. The question which of course presents itself must then be, how to dispose them for tiiis use ; and for this 256 VARIOUS KINDS OF FECULA. purpose they must be dissolved, as minutely divided as possible, and combined in such a manner that the imper- fections of those Avhich might be disposed to scale, may be corrected by others. Resins may be dissolved by three agents—1. By fixed oil. 2. By volatile oil. 3. By alcohol. And accord- ingly Ave have three kinds of varnish : the fat or oily var- nish, essential varnish, and spirit varnish. Before a resin is dissolved in a fixed oil, it is necessary to render the oil drying. For this purpose the oil is boil- ed A\rith metallic oxides; in which operation the mucilage of the oil combines Avith die metal, Avhile the oil itself unites with the oxigene of the oxide. To accelerate the drying of this varnish, it is necessary to add oil of tur- pentine. The essential varnishes consist of a solution of resin in oil of turpentine. The varnish being applied, the essen- tial oil flies off, and leaves the resin. This is used only for paintings. When resins are dissolved in alcohol, the varnish dries very speedily, and is subject to crack ; but this fault is corrected by adding a small quantity of turpentine to the, mixture, Avhich renders it brighter, and less britde Avhen dry. The coloured resins or gums, such as gum guttse, dra- gon's blood, &c. are used to colour varnishes. To give lustre to the varnish after it is laid on, it is rubbed Avith pounded pumice stone and water; which being dried with a cloth, the work is afterAvards rubbed with an oiled rag and tripoli. The surface is last of all cleaned Avith soft linen cloths, cleared of all greasiness \vhh 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 slight alteration of mu- cilage ; for it differs from that substance in no other re- spect than in being insoluble in cold water, in AA'hich li- Various kinds of fecula. 257 quid it falls with wonderful quickness. If it be put into hot water, it forms a mucilage, and resumes all its cha- racters. It seems that the fecula is simply a mucilage de- prived of caloric. In fact, a young plant is all mucilage; the old plants and fruits afford little fecula, because the heat is stronger in young than in old plants, according to Dr. Hunter. There are few plants which do not contain fecula. Mr. Parmentier has given us a list of all those which afford it, in his experiments. (See his Reclierches sur les Vegetaux Nourissans.) But the seeds of gramineous and legumi- nous vegetables, as Avell as the roots, which botanists call Tuberose, contain it-most plentifully. Nothing more is required, in order to extract the fecu- la, than to bruise or grind the plant in water; and the fecula, AA'hich is at first suspended in that fluid, soon falls to the bottom. We shall not in this place attend to any other feculse but such as are used in the arts or in medi- cine. Such are those of bryony, of potatoes, cassava, sago, salep, starch, &c* 1. The fecula of bryony is extracted from the root of that plant. The bark is first taken off from the root, which is then rasped, and submitted to the press. The juice which flows out by expression is rendered white and opaque by a fecula AA'hich subsides. The liquid is then decanted off, and the fecula dried. It is strongly purga- tive, on account of a portion of extract which it retains; but it may be deprived of its purgative virtue by careful washing in Avater. If water be poured on the marc which remains beneath the press, a large quantity is obtained which is not purgative, because the extractive matter was forced out by the first operation. Mr. Baume has pro- posed to substitute this fecula instead of starch. The fe- cula is afforded by similar treatment of the roots of corn- flag and arum. 2. That Avhich is generally knoAvn by the name of Po- tatoe FfoiTr, is nothing but the fecula of this root obtained by ordinary and easy processes. The root being well * The editor has obtained starch in large quantities, and of the best quality, from the seeds of the sscuhis pavia, horse ehesnut or buck eye, a native of this country.—Am. Ed. Vtft. II. Kk 258 Various kinds or fecula. vvashed, it is pounded or crushed in such a manner as perfectly to destroy its texture. The pulp is then put into a sieve, and water poured on it, Avhich carries off the fe- cula, and deposites it at the bottom of the receiving vessel. The \Aater, which is coloured by extractive matter, and part of the parenchyma that remains suspended, is de- canted off, and the deposition is washed several times. The colour of the fecula grows whiter as it dries; a^. when dry it is very A\hite and fine. As this fecula has become an article of common use for some time past, several instruments have been con- trived A\hich are more or less suited to bruise the potatoes. Rasps haA-e been proposed turning in cylinders, mills arm- ed with points of iron, he. 3. The cassava of the Americans-is extracted from the roots of the manioc. This plant contains an acrid and very dangerous poison, of AA'hich it must be very careful- ly deprived. The Americans take the fresh root of ma- nioc, Avhich they peelr rasp, and enclose in a bag or sack formed of rushes, and of a very open texture. This bag is suspended from a staff; and a very heavy vessel is fas- tened to its lower part, which draAA^s the bag down, so as in some measure to compress the root, at the same time that it receives the juice as it flows out. The juice is a most dreadful poison.. When the root is well cleared of the juice, it is put into the same bags, and exposed to dry in the smoke. The sifted root is called Cassava. To convert it into food, it is spread out upon a hot brick or plate of iron , and when the surface Avhich rests immedi- ately on the brick is of a reddish brown colour, it is turn- e the one and half of the other. 1 I Contain much citric, and f little or none of the ma- lic acid. J According to the same chemist, the juice of green grapes, as well as that of tamarinds, contains only the acid of citrons. Scheele has likeAvise proved the existence of the malic acid in sugar. If weak nitric acid be poured on sugar, and'distilled till the mixture begins to turn brown, ali the oxalic acid may be precipitated by the addition of lime-water; and another acid will remain, which the lime-AAater does not precipitate. To obtain this acid in a state of purity, the liquor is saturated by means of chalk, then filtered, and alcohol added, which, occasi- ons a coagulation. This coagulation, well Avashed in alcohol, is re-dissolved in distilled water. The malate of lime is decomposed by the acetate of lead; and, last of all, the malic acid is disengaged by the sulphuric acid. The alcohol by evaporation leaves a substance rather bitter than sweet, Avnicli is deliquescent, and resembles the saponaceous matter of lemon juice. If a small quan- tity of nitric acid be distilled from this, the malic and oxalic acids are obtained. ACIDS OF VEGETABLES. 279 By treating various other substances with the nitrie acid, the malic and oxalic acids are likewise obtained. Such are gum arabic, manna, sugar of milk, gum adra- gant, starch, and the fecula of potatoes. The extract of nut-galls, the oil of parsley seed, the aqueous extract of aloes, of coloquintida, of rhubarb, of opium, afforded not only the tAvo acids to Mr. Scheele, but likewise much resin. This celebrated chemist, by treating several animal substances Avith very concentrated nitric acid, obtained the malic and jtlie oxalic acids from them. Fish- glue, or isinglass, white of egg, yolk of egg, and blood, treated in the same manner, afforded the same products. There are few vegetables which do not exhibit some acid more or less developed. We see, for example, all fruits insipid at first become insensibly acid; and finish by losing that taste, and become saccharine. There are some which constantly preserve an acid taste, and form a a particular class. Some plants contain an acid principle diffused through the Avhole parenchyma or body of the vegetable. Such are the yellow gilly-floAver, bardana or waterdock, filipen- dula or droriwort, water cresses, the herb robert, &c. These plants sensibly redden blue paper. There are others in Avhich the acid principle exists only in part of the plant; as, for example, in the leaves of the greater valerian, the fruit of the winter cherry, and of the cornel tree, the bark of burdock, and the root of aristolochia or birth wort. Mr. Monro communicated some experiments to the Royal Society of London, in 1767, which prove that certain vegetables contain acids nearly in a disengaged state, and even such as are the least promising on a slight examination. 1. Having peeled two dozen of summer apples, and "cut them into small pieces, he poured water upon them, in Avhich he had previously dissolved two ounces of soda, and left the whole to stand for six days. The filtrated liquor, evaporated, and left in repose for six days more, afforded a beautiful salt in small 280 ACIDS OF VEGETABLES. round transparent plates, placed edgewise on each other. 2. The juice of mulberries clarified Avith the Avhite of egg, and saturateel Avith soda, afforded a pulveru- lent salt of no regular figure; Avhich by repeated solu- tions and evaporations, at last produced long crystals, one kind being thin, and the other thicker, which crossed each other. 3. He obtained small cubical or rhomboidal crystals by treating peaches and oranges with soda. 4. The green plum afforded, after seAreral soluti- ons and crystallizations, a neutral salt, Avhich crystal- lized without evaporation in large hexagonal plates, and partly in large rhomb i. This salt had a hot taste, and was soluble in three or four times its Aveight of cold Avater. 5. The red gooseberry afforded, by evaporation and cooling, small very hard rhomboidal crystals, not change- able in the air; whose taste resembled that of the salt produced by a combination of the citric acid with the same base. The green gooseberry produced a saline crust formed of small rhomboidal crystals, and covered Avith their bril- liant scales. 6. The green grape afforded Mr. Munro, by repeated solutions, a neutral salt, in small cubical crystals, of a rhomboidal or parallelogramic figure, lying upon and in- tersecting each other. The juice of hemloc afforded M. Baume a salt in small irregular crystals, nearly tasteless, but reddening the in- fusion of turnsol. 6. M. Rinmann, in his History of Iron, places the sorb- apple and sloe among the substances capable of corroding and cleansing the surface of this metal, on account of their acid. When, by the decomposition of certain vegetables by the nitric acid, an acid was obtained as the last result, it was thought to have existed ready formed in the vegeta- ble; but a more intimate examination sheAved that the acid made use of in this operation Avas merely decom- posed, while it destroyed the organization of the vegeta- ble, disunited the combinations which retained the prin- CONCERNING ALKALIS. 281 ciples, and that the oxigenous base of this acid, by* unit- ing with an element of the vegetable, formed a particular acid. This truth is deduced from the combined processes of M. Lavoisier, De Morveau, &c. It is to a similar cause that we ought to attribute the formation of the acetous, the carbonic, and other vegeta- ble acids; and even the rancidity of oils, and the altera- tion to which some other principles of the vegetable king- dom are subject. In these cases the air affords the oxi- gene which becomes fixed in the plant, and gives it ari4 acid nature. The oxalic acid does not exist ready formed in sugar, neither is the camphoric acid ready formed in camphor. The same may be observed of several other acids which are extracted by means of certain acids decomposed by being treated with vegetable substances. We shall speak of these acids when we come to treat of their radical principles. ARTICLE X. Concerning Alkalis. Alkali exists ready formed in plants. Duhamel and Grosse have proved that it might be extracted by means of acids. Margraff and Rouelle have added new proofs in support of the assertions of these chemists. They have observed, from their experiments, that the alkali ex- isted in a disengaged state in vegetables : but these expe- riments proved at most that their state of combination is such that it may be broken by the mineral acids. The alkali, in some instances, is nearly in a disengaged state; for it is found in combination Avith carbonic acid in the helianthus annuus. But the alkali of plants is often com- bined Avith the oily principle. When it is required to extract the alkali from a vege- table substance, all the principles with which it may be united, are destroyed by fire; and it is cleared from the residues of the combustion by lixiviation. This is die process used to make the impure alkali, called salin, as Ave have already observed. Vol. W N n 982 ALKALIS AND OTHER SALTS If wood remains a long time under water, it is depriv- ed of its property of affording an alkali by combustion; because the water dissolves the compounds which may contain it. Marine plants afford an alkali of another nature, knoAvn by the name of Soda. Vegetables possess the power of decomposing common sea salty and retaining its alkaline base. All insipid plants are capable of affording more or less of soda if they be raised on the sea coast; but they j>erish there in a short time. Ammoniac is likewise found in plants. The glutinous, part of gramineous vegetables contain it, and give it out to the nitric, muriatic, and other acids, according to Mr. Foulletier; and nothing more is required than to triturate the essential salt of wormwood with fixed alkali, to sepa- rate the volatile. This alkali appears to be one of the principles of the tetradynamia, as these afford it by sim- ple distillation. Alkalis likeAvise exist in plants in the state of neutral salts. They are combined with the sulphuric acid in old borage and in some astringent plants. The sulphate of potash appears to exist in almost all vegetables, as the pot- ash contains more or less of it; and the analysis of to- bacco has afforded me a considerable quantity. Tamarise affords the sulphate of soda in such abund- ance, that by extracting it from the ashes of this plant, it tan be afforded in very beautiful and pure crystals at thirty livres the quintal. The greater turnsol, parietaria, and borage, contain nitrate of potash. The muriates of soda and of potash are afforded by marine plants. We likewise find the alkalis combined with the acids of vegetation, such as the oxalic, the tartareous, and other acjds. It appears that the several salts are the products of the vegetation, and peculiar effect of the organization, of ve- getables. Two plants Avhich grow in the same soil, af- ford very different salts ; and each plant constantly affords the same kind. Besides this, Homberg observed (Mem. Acad. Par. 1669) that the same salts were developed by AFFORDED BY PLANTS. 283 plants eroAtfing in earths previously well washed, and af. terwards watered with distilled water. We may therefore class salts among the principles of vegetables, and no longer consider them as accidentally contained in plants. I do not hoAvever deny that the com- bustion of a plant may not give rise to some of them, and increase or diminish the proportions of others. Combus- tion must form combinations which did not exist in the plant, and destroy several of those which existed before. The atmospheric air employed in this operation must unite with certain principles, and produce various results. The nitrogene gas which is precipitated in torrents in the focus of combustion, probably combines with some of the principles to form alkalis, and consequently may augment the quantity of those which naturally exist in the plant ARTICLE XI. Concerning the Colouring Principles. The object of the art of dying consists in depriving one body of its colouring principle, to fix it upon another in a durable maimer; and the series of manipulations neces- sary to produce this effect, constitutes the art itself. This art is one of the most useful and wonderful of any we are acquainted with; and if there be any one of the arts which is capable of inspiring a noble pride, it is this. It not only affords the means of imitating nature in the riches and brilliancy of her colours; but it appears to have sur- passed her in giving a greater degree of brilliancy, fixity, and solidity to the fugacious and transient colours witii which she has clothed the productions around us. The series of operations which constitute the art of dy- ing, are absolutely dependant on the principles of chemis- try : and though it is to accidents, or the very slight com- bination of facts suggested by the comparison of a few circumstances, that Ave are indebted in this part of che- mistry for several excellent receipts, and some principles; yet it is not the less true, that no considerable progress will ever be made, nor any solid foundation established, but by analysing the operations, and reducing them to g£- 284 ART OF DYING. neral principles, AA'hich chemistry alone can afford. The necessity of establishing proper principles is still farttier evinced by the uncertainty and continual trials Avhich pre- vail in die manufactories. The slightest change in the nature of the substances puts the artist to a stand, inso- much that he is incapable of himself of remedying the defects AA'hich arise. Whence follow continual losses, and a discouraging alternation of success and disappointment. The little progress Avhich chemistry has hitherto made in the art of dying, depends on several causes, AA'hich we shall proceed to explain. The first cause of this slow progress depends on the difficulty of ascertaining with any degree of certainty the nature, properties, and affinities, of the colouring princi- ple. In order to extract this principle, we must be ac- quainted Avith the nature of its solvent; Ave must know whether the principle be in a state of purity, or mixed with other parts of the vegetable; whether this colouring matter consist of one principle alone, or is formed by the union of a number: we must also render ourselves ac- quainted with its affinities with various kinds of stuff; for it is ascertained by experience that certain colours adhere very well to wool, though they do not alter the whiteness of cotton. In addition to these necessary parts of know- ledge, it Avill likewise be required to determine its affinity with the mordant, for alum is the mordant for some co- lours and not others : besides which, the action or effect of other bodies upon the colour when dyed must be as- certained, in order to contrive the means of defending it from alteration, &c. The second cause which has retarded the application of chemistry to dying, is the difficulty the chemist finds in procuring opportunities of making experiments in the large Avay. Prejudice, which reigns despotically in the dye-house, tends to expel the chemist as a dangerous in- novator ; and the proverb, that Experience is better than Science, contributes to prevent the introduction of im- provements into manufactories. It is very certain that a dyer, confined to the mere practical part of his business, will Avithout controversy produce a better scarlet than a chemist who is acquainted only Avith the principles ; for the same reason as a simple Avorkman in clock making ART OF DYING. 285 will make a better watch than the most celebrated mecha- nic. In these cases we may admit that experience is bet- ter than science ; but when it is required to resolve any problem, to explain any phenomenon, or to discover some error in the complicated details of an operation, the mere artizan is at the end of his knowledge, is to- tally at a loss, and Avould derive the greatest advan- tage from the assistance of the man of science. Another cause of the sIoav progress of chemistry in the art of dying, is, that most of the works which treat, upon this art are confined to descriptions of the processes used in the manufactories. These works, it must be admit- ted, possess their advantages; but they do not advance die science of operations a single step. They only ex- hibit the sketch of a country, without indicating eitlier its relative situation, or the nature of its products. It has indeed been very difficult, till lately, to do more than this; because the gases, which are so greatly concerned in this part of chemistry, were unknown; because the action of light and of the air, which is so powerful upon colours, Avas a fact of which neither the cause nor the theory could be known; and more particularly because the salts and combinations of three, four and five princi- ples were not knoAvn, though they very much tend to render the effects of operations on vegetables more com- plicated. In order therefore to make a progress in the art of dying, Ave must ground our reasoning on other princi- ples. I shall proceed to sketch out a plan which seems to me to be adapted to this purpose. We shall ex- amine— 1. The manner in which the colours of various bodies are developed and formed. 2. The nature of the combinations of • these same colours in these bodies, and the properest means of ex- tracting them. 3. .The most advantageous processes for applying them. 1. Colours are all formed in the solar light. The proper- ty which bodies possess of absorbing some rays, and re- flecting others, forms die various tinges of colours with 286 ART OF DY1NC; which they are decorate^, as is proved from the experi- ments of Newton. From this principle we may consider the art of dying under two very different points of view. For Ave may determine the colour upon a body either by changing the form and disposition of its pores; so that it may acquire the property of reflecting a different kind of rays from those which it reflected before it was subjected to these mechanical operations. Thus it is that by trituration we change the colour of many bodies; and to this cause it is that we must refer all the effects dependant on the re- flexibility and refrangibility of rays. This coloration depends, as we see, merely on the changes produced in the surfaces of bodies, or the disposition of their pores. The phenomena of refrangibility depend on the density or specific gravity of bodies, according to Newton and Delaval. The other method of causing a body to exhibit a de- terminate colour, consists in transferring to the surface of , the body some other body or substance which pos- sesses the property of reflecting this known ray. This is the effect chiefly produced by dying. But in Avhat manner do the coloured bodies of the three kingdoms of nature acquire the property of constantly reflecting one determinate kind of rays ? This is a very delicate question; for the elucidation of which I shall bring together a few facts. It appears that the three colours which are the most eminently primitive in the arts; those which form all the others by their combination, and consequently the only colours to which Ave need pay attention; that is to say, the blue, the yellow, and the red—are developed in the bodies of the three kingdoms by a greater or less absorp- tion of oxigene, which combines with the various princi- ples of those bodies. In the mineral kingdom, the first impression of fire, or the first degree of calcination, develops a blue colour, sometimes interspersed with yellow, as is observable when lead, tin, copper, iron, or other metals, are exposed in a state of fusion to the action of the air, to hasten their cooling. This may be especially observed in steel plates which are coloured blue by heating. ART OF DYING. 28? Metals acquire the property of reflecting the yellow colour by combining with a greater quantity of oxigene; and accordingly we perceive this colour in most of them in proportion as the calcination advances. Massicot, li- tharge, ochre, orpiment, and yellow precipitate, are in- stances of this. A stronger combination of oxigene appears to produce the red; whence we obtain minium, colcothar, red preci* pitate, &c. This process is not uniform through all the bodies of the mineral kingdom; for it is natural to infer that the effects must be modified by the nature of the base with which the oxigene combines. Thus it is that in some of diem we perceive the blue colour almost im- mediately followed by a black; as may easily be ac- counted for, on the consideration that there is a very slight difference between the property of reflecting the weakest rays and that of reflecting none at all. To give additional force to the observations here made, we may also take notice that the metals themselves are most of them colourless, and become coloured by cal- cination; that is to say, by the fixation and combination of oxigene. The effects of the combination of oxigene are equally evident in the mineral as in the vegetable kingdom; and, in order to convince ourselves of this, we need only fol- low the operations in the method of preparing and devel- oping the principal blue colours, such as indigo, pastel, turnsol, &c. Indigo is extracted from a plant known by the name of Anillo by the Spaniards, and the Indigo Plant by us. It is the Idingofera tinctoria of Linnxus. It is cultivated at Saint Domingo, in the Antilles, and in the East Indies. The boughs are cut every two months, and the root lasts two years. The plant is laid to ferment in a trough called the steeping trough, which is filled Avith water. At the end of a certain time the water heats, emits bubbles, and becomes of a blue colour. It is then passed into another vessel or trough, called the beating trough (batterie,) where the fluid is strongly beaten or agitated by a mill Avith pallets, to condense the substance of the indigo. As soon as the water is become insipid, it is draAvn off- 288 ART OF DYING. and the deposition of the fecula is made in a third vessel, called the setding trough (reposoir), where it dries, and is taken out to form the loaves distributed in com- merce. The pastel is a colour Avhich is extracted in Upper Languedoc, by fermenting the leaves of the plant after having first bruised them. The fermentaion is promoted by moistening them with the most putrid Avater that can be procured. The woad is prepared in Normandy in the same man- ner as the pastel. Turnsol is prepared at Grand Galargues by soak- ing rags in the juice of the croton tinctorium, and afterwards exposing them to the vapour of urine or dung. We likewise observe that the first degree of combina- tion of oxigene with oil (in combustion) develops the blue colour for the instant. The blue colour is formed in dead vegetables only by fermentation. Now in these cases there is a fixation of oxigene. This oxigene combines with the fecula in indi- go, Avith an extractive principle in turnsol, &c.; and most colours are likeAvise susceptible of being converted into red by a greater quantity of oxigene. Thus it is that turnsol reddens by exposure to air, or to the action of acids; because the acid is decomposed upon the muci- lage, which is the receptacle of the colour; as may be seen in syrup of violets, upon which the acids are decomposed Avhen concentrated. The same thing does not happen Avhen a fecula is saturated with oxigene, and does not admit of the decomposition of the acid. Hence it is that indigo does not become red by acids, but is on the con- trary soluble in them. It is likeAvise for the same reason that Ave observe a red colour developed in vegetables in Avhich an acid continually acts, as in the leaves of the ox- alis, of the virgin vine, the common sorrel, and the ordinary vine. Hence also it happens that acids brighten most of the red colours; anel that a very high* ly charged metallic oxide is used as the mordant for scarlet. We find the same colours developed in the animal kingdom bv the combination of the same principle. NATURE OF COLOURS. 289 When flesh-meat putrefies, the first impression of the ox- igene consists in producing a blue colour; Avhence the blue appearance of mortifications, of flesh becoming pu- trid, of game too long kept, or the appearance which in our kitchens in France is called cordon bleu. This blue colour is succeeded by red, as is observed in the prepara- tion of cheeses, which become covered Avith a mouldiness at first of a blue colour, but afterwards becoming red : I have pursued these phenomena in the preparation of chee- ses at Rocquefort. The combination of oxigene, and the proportional cmantity which enters into such combination, determine therefore the property of reflecting any particu- lar rays of light. But it may easily be understood that the colour must be subject to variation, according to the nature of the principle with which it combines; and this points out a series of very interesting experiments that re- main to be made. All the phenomena of the combination of air with the several principles in different proportions, may be observ- ed in the flame of bodies actually on fire. This flame is blue when the combustion is slow; red, when stronger and more complete; and white, Avhen still more perfect For these final degrees of oxidation in general produce a Avhite colour, because all the rays are then equally re- flected. From the foregoing facts Ave may conclude that the blue ray is the weakest, and is consequently reflected by the first combination of oxigene. We may add the fblloAving fact to those we have already exhibited. The colour of the atmosphere is blueish: the light of the stars is blue, as M. Mariotte has proved, in the year 1678, by receiv- ing, the light of the moon upon Avhite paper: the liglit of a clear day reflected into the shade by snow, is of a fine blue, according to the observations of Daniel Major (E- phem. des. Curios, de la Nature, 1671, premier Dec.) The colouring principle is found in vegetables in four states of combination—1. With the extractive principle. 2. With the lvsinous principle. 3. With a fecula. 4. With a gummy principle.—These four states in which we find the colouring principle, indicate to us the means (df extracting it. Vol. II. Oo 290 VEGETABLE COLOURS. A. When the receptacle of the colour is of the nature of extracts, Avater is capable of dissolving the Avhole: such is that of logwood, turnsol, madder, cochenille, &c. Nothing more is necessary than to infuse these sub- stances in Avater, for the purpose of extracting their co- louring principle. If any stuff be plunged in this solu- tion, it AVill be covered Avith a body of colour,- Avhich Avill be a mere stain, that may be again cleared off by water. To obviate this inconA'enience, it has therefore been found necessary to impregnate the stuffs on Avhich the colours 'were intended to be applied A\ith some salt, or other prin- ciple, which might change the nature of the colouring matter, antl give it fixity, by depriving it of its solubi- lity in water. It is this substance which is distinguished "by the name of Mordant. It is likewise necessary that the mordant should have an affinity with the principle of colour, in order that it may become its receiver. Hence it arises that most of these colours, such as turnsol, Bra- sil wood, &c. are not fixed by these mordants ; hence also it arises that cochenille does not form a fine scarlet, unless it has tin for its mordant. It is necessary, moreover, that the mordant have a due relation to the nature of the stuff; for the same composition which gives a fine scarlet colour to wool, gives a colour of wine lees to silk, and does not even change the white colour of cotton. B. There are certain resinous colouring matters soluble in spirit of wine : such are the pharmaceutical tinctures : they are used only in the arts for dying ribbons. There are other colouring matters combined Avith feculae, Avhich water does not dissolve : rocou, archil, indigo, and the red colour of oriental saffron, are of this kind. Rocou is a resinous fecula obtained by macerating the seeds of an American tree called Urucu in AArater. In this operation the extractive part is destroyed by ferment- ation, and the resinous fecula is collected in a paste of a deep yelloAV colour. The paste of rocou, diffused in wa- ter Avith the impure alkali called cendres gravelees, af- fords a fine orange colour. Archil is a paste prepared by macerating certain mos- ses and lichens in urine wi;h lime. • Alkalis extract a vio- let colour*. Archil is made in Corsica, in AiiA'ergnc, at Lyons, &c. ART OF DYING. 291 The Archil of the Canaries is less charged with lime. That Avhich I procured, exhibited ia its texture the fibres of the plant, not completely decomposed by the fermenta- tion. The archil of the Canaries, or the archil in the herb, is afforded by a lichen called Orcella, rocella, lichen fruticulosus, solidus, aphyllus, subramosus, tuherculis al- ternis, Linnaei. Tne pareila or archil of Auvergne is made Avith the lichen parellus Linnaei. The colouring maners of tiiis class are all soluble in alkali or lime ; and these are the substances used to dissolve them in Avater, and precipitate them upon stuffs. Lime is the true solvent of indigo; but alkali is the solvent of odier substances of the same class. For example : when it is required to make use of the colouring matter of bas- tard saffron, the first proceeding consists in washing it in much water, to clear it of the extractive and yelloAvish principle, Avhich is very abundant; and the resinous prin- ciple is afterwards dissolved by means of alkali, from Avhich solvent it is precipitated upon the stuffs by means of acids. In this manner it is that the poppy-coloured silk is made. This resinous principle may also be combined with talk, after it has been extracted by an alkali, and pre- cipitated by an acid; in which case die result is vegetable red. To make this pigment, the yellow colour of saf- fron or carthamus is first extracted by means of washinr. Five or six per cent, of its weight of soda is mixed with the residue; and cold water poured on, which takes up a yelloAv matter; and this, by the addition of lemon juice, deposites a red fecula. The red fecula, mixed Avith a le- vigated talk, and moistened with lemon juice, forms a paste, which is put into pots to dry. If the red be soluble in spirit of wine, it is vegetable ; but if not it is mineral, and is usually vermillion. Acids may be used instead of alkalis in fixing some of these colours upon stuffs. To make a permanent blue, in- stead of dissolving indigo by means of lime, it is sometimes dissolved in oil of vitriol. This solution is pourefl into the bath, and the alumed stuff is passed through it. Flan- nels are dyed blue at Montpellier in this way. This opera- tion depends merely on an extreme division of the indigo by the acid. 292 ART OF DYING. D. There are some colouring principles fixed by a re • sin; but Avhich, by the assistance of extractive matter, may be suspended by water. The stuffs are boiled in this solution ; the resinous part applies itself to them, and ad- heres Avith sufficient solidity not to be again carried off by Avater. No preparation is required to dye Avith these ingredients, nothing more being necessary than to boil the stuff in a decoction of the colour. The principal substances of this kind are, the husk of Avalnuts, the roots of the walnut tree, sumach, santal, the bark of cider, &c. All these substances, which require no mordants, afford only a buff- coloured tinge, Avhich dyers call Root Colours. The co- louring matter, of certain vegetables may likewise be ex- tracted by oils. In this way oils are coloured red by in- fusing alkanet, or the root of a certain species of bugloss, in them. In order to apply colouring matter properly upon anv stuff, it is necessary to prepare the stuff, and dispose it to receive the colouring principle. For this purpose it must be Avashed, bleached, and cleared of that glutinous mat- ter Avhich elefends it from the destructiA^e action of the air Avhile it grows on the animal Avhich affords it; and impreg- nated Avith the mordant Avhich fixes the colour, and gives it peculiar properties. A. The first operation required to dispose a stuff to receive colour, is bleaching; because the Avhiter it is, the more natural and accurate Avill be the colour it takes. IT this precaution be not taken, the success Aviil be uncertain. To bleach piece goods, the operator is satisfied with boil- ing them in an alkaline lixivium, and exposing them af- terwards to the air, to render the Avhiteness more perfect. This operation depends on the action of the oxigene, Avhich combines with the colouring principle, and destroys it; as is evidently demonstrated by the late experiments of M. Berthollet on the oxigenated muriatic acid, which bleaches cloths and cottons with such facility, that it is already used for this purpose in several manufactories. Cotton is bleached in some manufactories by a Aery in- ' genious process. A boiler is firmly set in masonry, and a cover fitted to it in the strongest- manner; this boiler has an elliptical figure. Alkali rendered caustic by lime is ART OF DYING. 293 put into the bottom of this vessel; and the goods intend- ed to be bleached are put into a basket Avhich prevents their touching the sides of the boiler. When the piece- goods are properly placed, the covering is fixed on, which is pierced by a very small aperture, to permit a portion of the aqueous'vapour to escape. A degree of heat much superior to that of boiling water is excited in the solution of potash : and the heat, assisted by the corrosive action of the potash in this kind of Papin's digester, destroys the colouring principle of the cottons, and gives them the utmost Avhiteness. B. That kind of gluten Avhich eiwelops almost every animal substance, but more especially raAV silk, is insolu- ble in Avater and in alcohol. It is only attacked by alka- lis and soaps; and for this purpose the operation of cleans- ing is used. Any stuff may-be cleared of its glutinous part by boiling or eA'(en digesting it in a solution of alkali: but it has been observed that a pure alkali alters the good- ness and quality of the stuff; for Avhich reasons soaps have been substituted in its stead. For this purpose the stuff is steeped in a solution of soap, heated to a less degree than boiling. The academy of Lyons, in the year 1761, proposed a prize for the means of clearing raw silks with- out soap. It Avas adjudged to M. Rigaut, of St. Quen- tin, Avho proposed a solution of salt of soda. It has been lately ascertained that Avater, heated above the degree of ebullition, is capable of dissolving this co- louring principle. A boiler similar to that Avliich 1 have just described, may be used for this purpose. In order to bleach cotton, and dispose it for the dying processes, it is cleansed by means of a liquid soap made of oil and soda. The piece-goods are cleared by this boiling from the varnish, which AArould prevent the colour from applying and fixing itself in a permanent manner; at the same time that it opens the pores of the stuff for the better reception of the colour. When the piece is thus prepared, its pores being very open, and its colour very Avhite, nothing remains to be done previous to the application of the dye, but to im- pregnate it with the mordant or principle AA'hich is to re- ceive die colour and change its nature so much, that nei- 294 POLLEN OF VEGETABLES. ther water, soap, nor any of the reagents used as proofs, may be capable of extracting it. It is necessary therefore — I. That the mordant itself should be very Avhite, that it may not alter the colour presented to it. 2. That it be not subject .to corruption; and for this purpose it must be sought among the earths and metallic oxides. 3. That it be in a state of extreme division, in order that it may fix itself in the pores. 4. That it be insoluble in Avater and the other reagents. 5. That its affinity Avith the co- louring matter and the stuff be very great. Alum and the muriate of tin, are the two salts whose bases unite these properties in the most efficacious manner. The stuffs having undergone the previous operations are therefore steeped in solutions of these salts; and Avhen they are impregnated, they are passed through the colour- ing bath : and by the decomposition, or change of prin- ciples betAveen the mordant and the principle Avhich holds the colour in solution, the colour is precipitated on the base of the mordant, and adheres to it. Certain vegetable substances are likewise disposed to take some colours by animalizing them. In this way cow's dung and bullock's blood are used in dying cotton; for it is a decided fact that animal substances take colours better than vegetables. ARTICLE XII. Concerning the Pollen, or Fecundating Power of the Stamina of Vegetables. Modern discoveries and observations have pointed out the sexual parts of plants; and Ave find nearly the same forms in the organs, the same means in the functions, and the same characters in the prolific humours, as in animals. The prolific humour in the male part is elaborated by the anthera; and as the organs of the plant do not admit of an actual intromission of the male into the female, be- cause vegetables are not capable of loco-motion, nature has bestowed on the fecundating seed the character of a poAvder; AA'hich the agitation of the air, and other causes, mav earn' away and precipitate upon the female. There POLLEN OF vegetables. 295 is a degree of elasticity in the anthera, which causes it to open, and eject the globules. It has even been observed that the pistil opened at the same time, to receive the poh ten, in certain vegetables. The resources of nature to assure the fecundation are admirable. The male and fe- male parts almost always repose in the same flower; and' the petals are always disposed in the most advantageous manner to favour the reproduction of the species. Some- times the male and female are upon die same individual, but placed upon different flowers; at other times both are attached to isolated and separate individuals, and then the fecundation is made by the pollen which the wind or air detaches from the antheras, and transmits to the female. The fecundating powder has almost constantly the smell of the spermatic liquor of animals. The smell of cab- bages in blossom, of the chesnut tree, and most other ve- getables, exhibits this analogy to such a degree, that the one odour might even be mistaken for the other. The pollen is generally of a resinous nature, soluble in alkalis and in alcohol. Like resins, it is inflammable; and the aura Avhich is formed around certain vegetables at the time of fecundation, may be set on fire, as was ob- served by Mademoiselle Linne in the fraxinella. Nature, which has employed less (Economical means in the fecundation of plants, and who entrusts these opera- tions almost to chance, since she delivers the fecundating powder to die Avinds, must of course have been prodigal in the formation of this humour, more especially for the trees of the monoecia and dioecia genera, Avhere the pro- duction is more exposed to accidental impediments. Hence Ave may account for those pretended showers of sulphur, which are never common but in such districts as abound Avith the hazel, filbert, and pine-trees. As the pollen could not be exposed by nature to the va- rying temperatures of the atmosphere, she has facilitated its development in the most rapiei manner. A warm sun very frequently suffices to open the concealed organs of the plant, to develop and procure its fecundation. On this account the author of Les Etudes de la Nature affirms, that the coloration of plants is designed to reflect the iio-ht more vividly, and that most flowers affect the most ach'an- 296 FORMATION OF AVAX. tageous form to concentrate the solar rays on the parts of generation. The parts emploA/ed in these functions are endued Avith an astonishing degree of irritability. M. des Fontaines has made some very interesting observations on this sub- ject ; and the agitated motions Avhich some plants affect in order to foliOAY the course of the sun, arc determined by nature, in order that the great work of generation, favour- ed by the sun, may be accomplished in the least possible time. Concerning Wax. The AA'ax of bees is merely the pollen very little altered. These insects have their femurs proA idcel Avith rugosities to brush the pollen from the anther ?e, and convey it to their nests. There appears to exist in the very texture of some flowers, which are rich in fecundating powder, a matter analogous to Avax, which may be extracted by aqueous decoction. Such are the male catkins of the betula alnus, those of the pine, &c. the leaves of rosemary, of offici- nal sage, the fruits of the mirica cerifera, suffer Avax to transude through the pores. It appears that A\'ax and the pollen have for their basis a fat oil, Avhich passes to the state of resin by its combi- nation AAith oxigene. If the nitric or muriatic acid be di- gested upon fixed oil for several months, it passes to a state resembling Avax. Wax by repeated distillations, affords an oil AA'hich pos- sesses all the properties of volatile oils. It is reduced into Avarer and carbonic acid by combustion. The colouring matter of Avax appears to be of the same nature as that of silk ; it is insoluble in Avater and in alco- hol. . In the arts, Avax is bleached by dividing it prodigi- ously ; for Avhich purpose oil is poured in fusion upon the surface of a cylinder, which revolves at the surface of Avater. The wax Avhich falls applies itself to the super- ficies, and is reduced into A'ery thin flakes or ribbons. It is aftenvards exposed to the air upon tables, taking care 5ECRF.TI0N OF HONEY. 297 to stir it from time to time, and by this means it becomes white. Alkalis dissolve wax, and render it soluhle in water. It is this saponaceous solution Avhich forms the Punic wax. It may be used as the basis of several colours; and may be made into an excellent paste for washing the hands. It is likewise applied with a brush upon se- veral bodies: but it Avould be highly advantageous if it could be deprived of its solvent, which constantly acts, and is the cause why it cannot be applied to se- veral uses, in which otherwise it might be found advan- tageous. Ammoniac likewise dissolves it; and as this solvent is evaporable, it ought to be preferred when it is proposed to use the wax as a varnish. ARTICLE XIII. Concerning Honey. Honey, or the nectar of floAvers, is contained chiefly in the base of the pistil, or female organ. It serves as food for most insects which have a proboscis. These animals plunge their proboscis into the pistil, and suck out the nectar. It appears to be a solution of sugar in mucilage; the sugar is sometimes preci- pitated in crystals, as in the nectar of the floAver of bal- samina. The nectar undergoes no alteration in the body of the bee, since Ave can form honey by concen- trating the nectar. It retains the odour, and not un- frequentiy the noxious qualities of the plant which af- fords it. • The secretion of the nectar is made during the sea- son of fecundation. It may be considered as the vehi- cle and recipient of the fecundating dust, which fa- cilitates the bursting of the globules, filled with this fecundating poAvder: for Linnaeus and Tournefort have Vol. II. Pp 298 PROPERTIES OF AV OODY MATTER. both observed that nothing more is required than to expose the pollen upon Avater, to assist the deA'.elopment. All the internal part of the style of the pistil is impregnated with it. And if the internal part of the female organs be dried by heat, the pollen no longer fecundates. Honey exudes from all the female parts, but particu- larly from the ovaria. Pores may even be observed in hyacinths, through which it fioAvs. Such floAvers as have only the male parts do not in general afford honey; and the organs AA'hich afford the nectar dry up and wither from the moment the act of conception is accomplished. Honey may there- fore be considered as necessary to fecundation; it is the humour afforded by the female to receive the fe- cundating poAvder, and facilitate the opening and ex- plosion of the small bodies Avhich contain the pollen; for it has been observed that these bodies open the m< ment they touch the surface of> any liquid AA'hich mois- tens them. ARTICLE XIV. Concerning the Ligneous Part of Vegetables. Chemists have constantly directed their attention to the analysis of vegetable juices : but they appear to have com- pletely neglected the solid part of the a cgetable, Avhich in every point of view is entitled to particular attention. It is this ligneous portion Avhich forms the vegetable fibre; and this matter not only constitutes the basis of the vegeta- ble, but is likewise developed in circumstances Avhich de- pend on the vital functions of the plant. It forms the pulp of seeds, the lanuginous covering Avhic'i overspreads certain plants, &c. The character of the ligneous part is, an insolubility in AA'ater and almost ewery other men- struum. The sulphuric acid only blackens it, and is de- composed upon it, as is likewise the nitric acid. Lut one very peculiar character of this principle is, that the concourse of air and water alters it very difficultly; and PROPERTIES OF WOODY MATTER. 299 that when it is well deprived of all its moisture, it abso- lutely resists every kind of fermentation; insomuch that it would be indestructible, if insects had not the proper- ty of gnawing and feeding upon it. It appears that the vegetable fibre consists of the basis of mucilage, harden- ed' by its combination Avitha greater quantity of oxigene. Several reasons lead us to adopt this idea. In the first place, the diluted nitric acid being put to digest upon fecula is decomposed, and causes the fecula to pass to a state resembling that of ligneous matter. I have ob- served, in the second place, that those fungi which grow in subterraneous places void of light, and are resolved into a very acid water, if left in a A'essel, acquire a greater quantity of the ligneous principle, in proportion as they are exposed by degrees to the light; at the same time that the acid is diminished by decomposition, and at length disappears. The transition of mucilage to the state of ligneous matter is very evident in the growth of vegetables. The cellular envelop which is immediately covered by the epidermis exhibits nothing but mucilage and glands; but by degrees it hardens, forms a stratum of the corti- cal coating, and at last concludes by becoming one of the ligneous rings. We observe this transition in certain plants which are annual in cold climates, and Aivacious in temperate climates. In the former they are herbaceous, because the periodical return of the colel Aveather does not permit them to develop themselves. In the second they become arborescent; and the progress of time hardens the muci- lage, and forms ligneous coatings. The induration of the fibrous part may be accelerated by causing the air and light to act more strongly upon it. M. de Button has observed that, Avhen a tree is deprived of its bark, the external part of the wood which is ex- posed to the air acquires a considerable degree of hardness; and trees thus prepared form pieces of carpentry much more solid than those which have not undergone such preparation. It is probably owing to the large quantity of pure air with which the fibrous matter is loaded, that it is not dis- FIXED PRINCIPLES OF VEGETABLES. posed to putrefy: and it is in consequence of diis most va- luable property of not being subject to corruption, that arts have been invented for clearing it of all fermentable prin- ciples of the vegetable kingdom, to obtain it in its greatest purity in the fabrication of cloths, paper, &x. We shall again return to these objects, Avhen avo treat of the altera- tions to which the vegetable kingdom is subject. ARTICLE XV. Concerning other fixed Principles of the Vegetable Kingdom. The volatile oil of horse-radish had formerly afforded sulphur, Avhich is deposited by standing, according to the observations of some chemists; but M. Deyeux has taught us to extract this inflammable principle from the root of the herb patience. Nothing is re- quired to be done but to rasp the root, boil, take off the scum, and dry it. This scum affords much sulphur in substance; and it is perhaps to this principle that these plants OAve their virtue, since they are used in skin dis- orders. Vegetables in their analysis likeAvise present us with certain metals, such as iron, gold, and manganese. The iron forms near one-tAvelfth of the weight of the ashes of hard wood, such as oak. It may be extracted by the magnet. It does not appear to exist in a perfectly dis- engaged state in the vegetable; nevertheless we read, in the Journaux de Physieme, an observation in which it is affirmed, that it Avas found in metallic grains in fruits. The iron is usually held in solution in the acids of vege- tation, from AA'hich it may be precipitated by alkalis. The existence of this metal has been attributed to the wearing of ploughshares, and other instruments of hus- bandry, and to the faculty aa hich plants possess of imbib- ing it Avith their nutritive juices. The Abbe Nolet and others have embraced this unphilosophical notion. It is SULHHUR, &C. FOUND IN VEGETABLES. 301 the same Avith the iron as with the other salts. They are produced by vegetation; and vegetables watered with dis- tilled water afford it as well as others. Beccher and Kunckel ascertained the presence of gold in plants. M. Sage Avas invited to repeat the processes by way of ascertaining the fact. He found gold in the ashes of vine twigs, and announced it to the public. After this chemist, most persons who have attended to this object have found gold; but irt much less quantity than M. Sage had announced. The most accurate analyses have shewn no more than two grains; whereas M. Sage had spoken of several ounces in the quintal. The process for extracting gold from the ashes consists in fusing diem Avidi black flux and minium. The lead which is produced is then cupelled, to ascertain the small quantity of gold Avith which it became alloyed in this operation. Scheele has also obtained manganese in the analysis of vegetable ashes. His process consists in fusing part of the ashes Atith three parts of fixed alkali, and one-eighth of nitrate of potash. The fused matter is- boiled in a certain quantity of water. The solu- tion being then filtered, is saturated with sulphuric acid, and at the end of a certain time manganese falls doAvn. Lime constantly enough forms seA'en-tenths of the fixed residue of vegetable incineration. This earth is usually combined Avith the carbonic acid. Scheele has proved that it effloresces in this form on the bark of guaiacum, die ash, &c. It is likewise very often united with the acid of vegetation. It appears to be formed by an al- teration of the mucilage, more advanced than that Avhich fonns the fecula, which has some analogy with this earth. We evidently see the transition of mucilage to the state of earth in testaceous animals. We observe the mucilage putrefy at its surface, with so much the more facility as it is purer; as we may judge by a comparison of the as- terise, the sea hedge-hog, the crab, &c. Next to lime, alumine is the most abundant earth in vegetables, and next magnesia. M. Darcet lias obtained, from one pound of the ashes of -beech, one ounce of the sulphate of magnesia, by treating them with the. 302 EXPRESSES JUICES OF VEGETABLES. sulphuric acid. This earth is very abundant in the ashes of tamarisc. Siliceous earth likewise exists, but less abundantly. The least common of all is the barytes. ARTICLE XVI. Of the common Juices extracted by Incision or Expres sion. The vegetable juices hitherto treated of are peculiar subsUaices contained in Aregetables, and possessing striking characters, by Avhich the) are distinguishable from every other humour. But Ave may at once extract from vegeta- bles all the juices they contain; and this mixture of va- rious principles may be obtained by several methods. Sim- ple incision is sometimes sufficient; but expression is 'equally used. The juices of vegetables vary according to the respect- ive 'nature of the plants. They are more abundant in some than in others. Age modifies them. Young trees in general have most sap; and this sap is milder, more mucilaginous, and less charged with oil and resin. The sap varies according to the season. In the spring the plants draw up with avidity the juices afforded by the air and the earth; these juices establish a plethora every where, from which results a considerable groAvth of the individual, and sometimes a natural extravasation. If in the time of plethora incisions be made in an)' part of the vegetable, all the abundant sap escapes by the aperture; and this fluid is almost always clear, and without smell. But by degrees the plant elaborates these juices, and gives them peculiar characters. In the spring the sap in the bo- dy of the vegetable presents only a slight alteration of the nutritive juices; but in the summer the whole is elabo- rated, all is digested, and then the sap possesses charac- ters very different from those it possessed during the spring season. If incisions be now made in the tree, the juices obtained are accordingly very different; and for this rea- son it is that the juices dispersedjn commerce are extract- ed during the summer. EXTRACTION OF MANNA. 303 The constitution of the air equally influences the nature of vegetable juices. A rainy season opposes the deve- lopment of the saccharine principle, as well as the forma- tion of resins and aromatic substances. A dry season af- fords little mucilage, but much resin and aromatic princi- ple ; hot weather decomposes the mucilage, and favours the development of resins, saccharine matter, and aroma; but a cold season does not permit the formation of any principle but mucilage : and as the mucilage is the prin- ciple of increase of bulk in plants, the whole of this sub- stance is employed for that purpose ; while the heat and light modify the same mucilage, and cause it to pass to the state of oil, resin, arcma, &c. Hence probably it is that trees have a more agreeable appearance in cold than in burning climates; and that the trees in this latter situation abound with aromatic, oily, and resinous prin- ciples. In the vegetable as in the animal kingdom, spirit appears to be the portion of the southern climates; Avhile force and strength are attributes of the northern. Concerning the Juices extracted by Incision. The juice contained in plants, and knoAvn by the name Of Sap, is dispersed through the cellular tissue, enclosed in the vessels, or deposited in the utricules : and there is a communication existing, Avhich, when any part of the vegetable is wounded, causes the abundant juices to flow through the aperture ; not indeed so speedily, nor so .com- pletely, as in animals; because the humours do not pos- sess so rapid a motion, and because there is less connex- tion betAveen the several organs in vegetables than in ani- mals. The sap is a confused mixture of all the princi- ples of vegetables. The oil and the mucilage are con- founded with the salts. It is, in a word, the general hu- mour of vegetables, in the same manner as the blood in animals. In the present place Ave shall speak only of man- na and opium. 1. Manha.-^-Sc-veral vegetables afford manna; and it is extracted from tlu pine, the fir, the maple, the oak, the juniper, the fig, the willow, the olive, &c- but the ash, 304 CHARACTERS OF MANNA. larch, and the alhagi, afford it in the largest quantities. L'obci, Rondelet, and others, have observed at Montpel- lier, upon the olive trees, a kind of manna, to Avhich they have given the name of celiomeli. Tournefort collected it from the same trees at Aix, and at Toulon. The ash A\hich affords manna grows naturally in all tem- perate climates; but Calabria and Sicily appear to be the most natural countries to this tree ; or at least it is only in these countries that it abundantly furnishes the juice called Manna in commerce. The manna Aoavs naturally from this tree, and attaches itself to its sides in the form of Avhite transparent drops; but the extraction of this juice is facilitated by incisions made in the tree during summer : the manna flows through these apertures upon the trunk of the tree, from which it is detached Avitii Avooden instruments. Care is likewise taken to insert straws, or small sticks of wood, into these incisions ; and the stalactites Avhich hang from these small bodies are separated, and known in commerce by the name of Manna in Tears : the smallest pieces form the manna in sorts or flakes; and the common or fat manna is of the Avorst quality, because the most contaminated with earth and other foreign substances. The ash sometimes affords manna in our climates, specimens of which I have seen collected in the vicinity of Aniane. The larch Avhich groAvs abundandy in Dauphiny, and the environs of Briancon, likeAvise affords manna. It is formed during the summer on the fibres of the leaves, in Avhite friable grains, Avhich the peasants collect and put into pots, which tiiey keep in a cool place. This manna is of a yellow colour, and has a very nauseous smell. The aihagi is a kind of broom, Avhich groAvs in Persia. A juice transudes from its leaves, in the form of drops of various sizes, AA'hich the heat of the sun indurates. An interesting account of this tree may be seen in Tourne- fort's Travels. This manna is known in the Levant, in the toAATi of Tauris, by the name of Tereniabin. The inanna most frequently used is that of Calabria. Its smell is sttong, and its taste sweetish and nauseous: if exposed on hot coals, it SAvells up, takes fire, and leaves a light bulky coal. EXTRACTION OF OPIUM. 305 Water totally dissolves it, Avhether hot or cold. If it be boiled with lime, clarified Avidi white of egg, and con- ceit rated by evaporation, it affords crystals of sugar. Manna affords by distillation water, acid, oil, and am- moniac ; and its coal affords alkali. This substance forms thp basis of most purgative. me- dicines. 2. Opium.—The plant which affords opium is the pop- py, which is cultivated in Persia and Asia Minor. To extract this precious medicine, care is taken to cut off all the flowers which would load the plant, and to leave that only which corresponds with the principal stem. At the beginning of summer, when the poppy-heads are ripe, in- cisions are made quite round them, from Avhich tears flow that are carefuily collected. This opium is the purest, and is retained in the country for various uses. That which comes to us is extracted by pressure from the same heads. The juice thus obtained is wrapped up, after pre- vious drying, in the leaves of the poppy, and comes to us in the form of circular flattened cakes. In our laboratories it is cleared from its impurities by solution in hot Avater, filtration, and evaporation to the con- sistence of an extract. This is the extract of opium. Opium contains a strong and narcotic aroma, from which it is impossible to clear it, according to Mr. Lorry. It likeAvise contains an extract soluble in water, and a re- sin ; together widi a volatile concrete oil, -and a peculiar salt. By long digestion in hot Avater the volatile oil becomes attenuated, is disengaged, and carries the aroma Avith it; so that by this means die oil and aroma may be separated, at least for the most part. It has been observed that opi- um deprived of this oil, a portion of its aroma, and its resin, preserved its sedative virtue,' Avithout being narco- tic and stupifymg. We are indebted to Baume for a se- ries of interesting researches on this subject. He boiled four pounds of sliced opium in between twelve and fif- teen pints of Avater, for half an hour. The decoction was straiiied with pressure, the dregs Avere exhausted by ebul- lition with more water. All these Avaters were mixed to- gether, and reduced by evaporation to six pints. The li- quor Avas then put into a cucurbit of tin, and digested on Vor. II. Qq 306 PROCESS WITH OPIUM. a sand-bath for six months, or during three months night and day. Care Avas taken to add Avater as the evaporation proceeded ; and the bottom of the vessel a\ as scraped from time to time, to disengage the resinous matter which sub- sided. When the digestion Avas finished, the litjuor was filtered, the residue carefully separated, and tire water evaporated to the consistence of an extract. If the salt be required to be separated, the evaporation must be suspended when the fluid is reduced to one pint. An earthy salt falls down by cooling, Avhich is of a ruddy appearance, and has the form of scales mixed Avith nee- dled crystals. Bs his long but judicious process, the oil is first separat- ed ; Avhieh after three or four days rises to the surface of the liquor, where it forms an adhesive pellicle, like turpentine. This pellicle is gradually dissipated, and disappears at the end of a month, nothing more being seen than a few drops from time to time. In proportion as the oil is dissipated, the re^in, which formed a soap AAith it, is precipitated. Mr. Baume has calculated that these principles exist in the folloAving proportions:—Four pounds of common opium afford one pound one ounce of marc or insoluble matter, one pound fifteen ounces of extract, twelve ounces of resin, one gross or dram of salt, three ounces seven gros of dense oil or aroma. Mr. Bucquet proposed to extract the sedative prin- ciple, by dissolving it in the cold, and aftenvards evapo- rating it; Mr. Josse, by agitating it in cold water; Messrs. De Lassone and Cornette, by dissolving, filtering it se- veral times, and ahvays evaporating it to the consistence of an extract. The sedative principle is a medicine of the greatest value, because it does not produce that drunkenness and stupor Avhich are too commonly the effects of crude opium. When a plant does not afford its juice by incision, this may happen either because the quantity is too small, or * because its consistence is not sufficiently fluid, or ' because there is not a sufficiently perfect communi- c; tion betAveen the vessels of the plant to permit the flowing of all the juice. In these ca.es the desired effect mav be produced either by simple mechanical pressure, EXPRESSSED VEGETABLE JUICES. 307 as in extracting the juice of hypocistus and acacia; or by the assistance of Avater, Avhich sofiens the texture of the vegetable, at the same time diat it dissob es and car- ries oft* the juice. Concerning Vegetable Juices extracted by Pres- sure. The succulent vegetables afford their juice by simple pressure ; and the method of performing this operation is nearly the same in all piants. When it is intended to ex- tract the juice of a plant, it is washed, cut into small pie- ces, pounded in a marble mortar, put into a linen bag, and pressed in a press. There are some ligneous plants, such as sage, thyme, and the lesser centaury, whose juices cannot be extracted without the additon of a small emantity of water; there are other very succulent plants, such as borage, bugloss, and chicory, Avhose juices are so viscid and mucilaginous as not to pass through a cloth unless a small quantity df water be added during the pounding. Inodorous plants may likewise be left to macerate, in order to prepare them for the extraction of their juices. The vegetable juices may be clarified by simple repose, or by filtration; when very fluid, by white of egg, or animal lymph, boiled Avith them ; and when the juices contain principles wiiich may be evaporated, such as those of sage, balm, ma joram, Sec. the vial AA'hich contains the juice is plung- ed in boiling water, after having closed it with a paper with a hole pierced through it; and Avhen the juice is clarified, it is taken out, dipped in cold AA'ater, and de- cantecL The juice of acacia is extracted from the same tree AAiiich affords gum arabic. The fruits of this tree are collected before they are ripe ; then pounded, pressed, and the juice dried in the sun : it forms balls of a black- ish broAvn internally, redder externally, and of an as- tringent taste. A juice is prepared Avith unripe sloes, Avhich is sold, under the name of German Acacia, and does not differ much from diat of Egypt. 508 VEGETABLE OXIGENOUS GAS. The juice of hypocistus is extracted from a parasitical plant Avhich grows en the cistus in'the island of Crete. The frui. is pounded, the juice extracted by pressure, and thickened in the sun; it becomes black, and of a. firm consistence. These tAvo last mentioned juices are used in medicine as astringents. SECTION IV. ^Concerning such Principles as escape from Vegetables by Transpiration. VEGETABLES being endued with digestive organs, throw oft* all such principles as cannot be assimi- lated by them; and when the functions of the ve- getable are not favoured by such causes as facilitate them, the nutritive juices are rejected nearly unalter- ed. We shall here attend to three principal vjsubstan- ces that exhale from vegetables, viz. air, water, and aroma. ARTICLE I. Concerning Oxigenous Gas afforded by Vegetables. Dr. Ingenhousz published, in the year 1779, Expe- riments upon Vegetables, in Avhich he affirms that plants possess the property of emitting vital air when acted upon by the direct rays of the sun; and that they emit a very mephitic air in the shade, and during the night. VEGETABLE OXIGENOUS GAS. 309 Doctor Priestley made knoAvn the same results at the same time, as Avell a» Mr. Senebier of Geneva, Avho never- theless did not publish a Avork on this subject until the year 1782, in Avhich he admits, as a general principle, that plants suffer vital air to escape in the sun-shine : but he maintains that they do not produce mephitic air in the shade; and is of opinion that, if Dr. Ingenhousz ob- tained any, it arose from a commencement of putrefaction in the plant. The simplest process for extracting this gas from vegetables, consists in immersing them under Avater, beneath an inverted glass Aressel. It is then seen, when the sun acts on the plant, that small bubbles are emitted, which gradually groAV larger, arise from the fibres of the leaf, and ascend to the surface of the fluid. All plants do not afford gas with die same facility. There are some Avhich emit it the moment the sun acts upon them: such are the leaves of the jacobasa, of lavender, and of some aromatic plants. In other plants the emission is sloAver; but in none later than seven or eight minutes, provided the sun's light be strong. The air is almost totally furnished by the inferior surface of the leaves of trees: it is not the same with herbs; for these afford air from nearly the whole of their surface, according to Senebier. The leaves afford more air when attached to the plant than Avhen gathered ; and the quantity is likewise greater the fresher and sounder they are. Young leaves afford but a small quantity of vital air; those which are full grown afford more, and" the more the greener they are. Leaves Avhich are injured, yellow, or red, do not afford it. Fresh leaves cut in pieces afford air; and the oxigene gas is capable of being emitted without the plant being plunged under water, as is proved from the experiments of Mr. Senebier. The parenchyma of the leaf appears to be the part Avhich emits the air. The epidermis, the bark, and the white petals, do not afford air; and in general it is only the green parts of plants which afford oxigenous gas. 310 VEGETABLE OXIGENOUS CAS. Green fruits afford air, but those Avhich are ripe do not; and the same is true of grain. It is proveel that the sun does not act in the producti- on of this phenomenon as a body Avhich heats. The emission of this gas is determined by the light; and I have even observed that a strong light, Avithout the direct action of the sun's rays, is sufficient to produce this phe- nomenon. It is proved, by the experiments of Mr. Senebier, that an acid diluted in Avater increases the quantity of air Avhich is disengaged, Avhen the water is not too much acidulated; and in this case the acid is decom- posed. It has been observed that the conferva affords much vi. tal air; as Avell as the green matter Avhich is formed in A\ater, and is supposed by Ingenhousz to be a col- lection of greenish insects. Pure air is therefore separated from the plant by the action' of light; and the excretion is stronger accord- ingly as the light is more vivid. It seems that light favours the work of digestion in the plant; and that the vital air, Avhich is one of the principles of almost all the nutritive juices, more especially of Avater, is emitted, when it finds no substance to combine with in the ve- getable. Hence it arises that plants Avhose vegetation is the most vigorous, afford the greatest quantity of air: and hence likeAvise it is that a small quantity of the acid mixed Avith the water favours the emission and increases the quantity of oxigenous gas. By this continual emission of vital air,. the Author ©f nature incessantly repairs the loss Avhich is produced by respiration, combustion, and the alteration of bodies, AA'hich comprehends every kind of fermentation arid pu- trefaction ; and in this manner the equilibrium betA^; n the constituent principles of the atmosphere is always kept up.* * Vide Note, pa^e 80, vol. 1. AROMA, OF SPIRITUS RECTOR. 3U ARTICLE II. Concerning the Water afforded by Vegetables. Plants likewise emit a considerable quantity of Avater, in the form of vapour, through their pores ; and this ex- eretion may be estimated as the most abundant Hales has calculated that the transpiration of an adult plant, such as the helianthus annuus, AA'as in summer seven times more considerable than that of man. Guettard has observed that this excretion is always in proportion to the intensity of the light, and not of the heat; so that there is scarcely any during the night. The same philosopher has observed that the aqueous transpiration is more especially made from the upper surface of the leaf. The water which exhales from vegetables is not pure, but serves as the vehicle of the aroma; and even carries Avith it a small quantity of extractive matter, Avhich causes it to corrupt so speedily. The immediate effect of the aqueous evaporation con- sists in maintaining a degree of coolness in the r' :rt,, which prevents its assuming the temperature of the atmos- phere. ARTICLE III. Concerning the Aroma, or Spiritus Rector. Each plant has its characteristic smell. This odorant principle was distinguished by Boerhaave by the name of Spirit us Rector, and by the moderns under the name of Aroma. The aroma appears to be of the nature of gas, from its fineness, its invisibility, &c. The slightest heat is suffi- cient to expel it from plants. Coolness condenses it, and rei tiers it more sensible ; and on this account the smell of plants is much stronger in the morning and evening. 312 EXHALATIONS OF PLANTS. This principle is so subtile, that the continual emission of it from a wood or flower does not diminish its weight, even after a very considerable time. The aroma is sometimes fixed in an extract, sometimes in an oil, anel this last combination is the most usual. It even appears to constitute the volatile character of the es- sential or Aolatile oils. The nature of the aroma appears to vary prodigiously; . at least if Ave may judge by the organ of smell, Avhich dis- tinguishes several species. There are some Avhich have a nauseous or poisonous effect on the animal economy. In- gcnliousz quotes an instance of the death of a young avo- man occasioned by the smell of lilies, in 1719; and the famous Triller reports the example of a young woman AA'ho died in consequence of the smell of violets, Avliile another Avas saved by removing the floAvers. Martinus Cromerus exhibits likewise an example of a bishop of Breslau Avho died by a similar cause. The mancenille tree which groAvs in the West-Indies, emits very elangerous vapours. The humour which flows from this tree is so unwholesome, that if it drop on the hand it raises a blister. The American plant lobelia longiflora produces a suffo- cating oppression in the breast of those Avho respire in its vicinity, according to Jacquin, Hortus Vinelobonensis. The rhus toxicodendron emits so dangerous an exhalation, that Ingenhousz attributes the return of a periodical disor- der, which attacked the family of the curate of Crossen in Germany, to a bench shaded by this tree, under which they had the custom of sitting. Every one knows the effects of musk and oriental saffron on certain persons; and the exhalation of the walnut-tree is considered as very unwholesome. We nn.y here mention the noxious property of those canes or reeds which in this country are used to cover roofs and dunghills, 8tc. Mr. Poitiven saw a man Avho Avas very iii on account of having handled these canes: the parts of generation were prodigiousy swelled. A dog which had slept upon the reeds suffered in the same man- ner, and was affected in the same parts. The method of ex -acting the aroma varies according to its volatility and affinities. It is in general soluble in VARIOUS PERFUMES. 313 AVater, alcohol, oils, &e. and these fluids are severally employed to extract it from plants Avhich afford it. When Avater or alcohol are used, they are distilled by a gentle heat, and the aroma comes over with them. Sim- ple infusion may be used; and in this Avay the loss of a portion of the aroma is avoided. Water charged with aroma is known by the name of the distilled Avater of the substance made use of. The distilled water of inodorous or herbaceous pianos does not appear to possess any virtue; and the apothecaries have long since decided the question, by substituting spring water in its place. Spirit of Avine combined Avith the same principle, is knoAvn by the name of die spirit or quintessence of the vegetable. When the aroma is very fugacious, such as that of li- lies, jasmine, or tuberose, the floAvers are put into a tin cucurbit with cotton steeped* in oil of ben. The cotton and the floAvers are disposed in alternate layers; the cu- curbit is closed, and a gentle heat applied. In this man- ner the aroma is permanently combined Avith the oil. These are the three methods used to retain the odorant principle. The art of the perfumer consists in applying them at pleasure to various substances. Perfumes are either elry or liquid. Among the first we may place the sachets, or little perfumed bags, which contain either mixtures of aromatic plants, or aromas in their native state; the perfumed powders, which obtain their smell by a few drops of the solution of aroma; the pastilles or comfits Avhich have sugar for their basis, &c. Liquid perfumes most commonly consist of aroma dis- sohreei in water or alcohol; the various liqueurs, or scent- ed spirituous cordial Avaters, are nothing else but the same solutions diluted with Avater, and SAveetened with sugar. For example, to make the eau divine, the bark of four citrons is taken, and put into a glass alembic, Avith two pounds of good spirit of wine, and two ounces of good orange-floAverwater; after which,distillation is performed on the sand-bath. On the other hand, one po .nd and a half of sugar is dissolved in one pound and a half of water. The two liquors being mixed, become turbid ; but, be- ing left to stand, the result is an agreeable liquor. Vol. II. Rr 314 DECOMPOSITION OF VEGETABLES. To make the cream of roses, I take equal parts-of rose- water, spirit of AA'ine a la rose, and syrup of sugar. I mix these three substances, and colour the mixture with the refusion of cochenille. But it must be alloAved that, in all perfumes which are a little complicated, the nose is the best chemist that can be consulteel; and a good nose is as* requisite and es- sential to a perfumer, as a strong head is to a geometer. SECT. V. Concerning the Alterations to which Vegetables are sub- ject after they are deprived of Life. THE same principles Avhich maintain life in vegeta- bles and animals, become the speediest agents of their destruction Avhen dead. Nature seems to have en- trusted the composition, maintenance, and decomposition of these beings to the same agents. Air and water are the tAvo principles which maintain the life in living beings; but the moment they are dead they hasten their alteration and dissolution. The heat itself, which assisteel and fo- mented the functions of life, concurs to facilitate the de- composition. Thus it is that the frosts of Siberia pre- serve bodies for several months; and that in our mountains thev are kept for a long time on the snow, Avhen it inter- cepts the carrying them to the place of interment. We shall examine the action of these three agents, namely, heat, air, and water; and Ave shall endeavour to sheAV the power and effect of each before we sliall attend to their combined action. DISTILLATION OF VEGETABLES. 315 CHAP. I. Concerning the Action of Heat upon Vegetable Sub- stances. THE distillation of plants by a naked fire is nothing but the act of decomposing them by. means of sim- ple heat. This process was for a long time the only me- thod of analysis. The first chemists of Paris adopted it for the analysis of near one thousand four hundred plants: and it was not till the commencement of the present cen- tury that this labour was discontinued; a labour Avhich did not seem to advance the science, since in this way the cabbage and hemlock afforded the same products. It is clear that an analysis by the retort ought not to shew the principles of vegetation: for, not to mention that heat changes their nature by becoming a constituent part of the principles extracted; these principles them- selves become mixed together, and Ave can never know their order or state while in the living plant. The action of the heat moreover causes the A'egetable principles to react upon each other, and confounds the whole together. Whence it arises that all vegetables afford nearly the like principles; namely, Avater, an oil more or less thick, an acid liquor, a concrete salt, and a coal or caput mortuum more or less abundant. Hales took notice that the distillation of vegetables af- forded mueh air; and was even in possession of an appa* ratus to collect and measure it. But in our time the me- thods of collecting and confining the gases are simplified; and the hydro-pneumatic apparatus has proved that the substances are formed of a mixture of carbonic acid, hy- drogene, and sometimes a little nitrogene. The order in which the several products are obtained, and the characters they exhibit, lead us to the following observations : 1. The water wiiich passes first is usually pure, and without smell; but when odorant plants are distilled, the first drops are impregnated with their aroma. These first portions of Avater consist of that which \A'as superabun- \ 316 DISTILLATION OF VEGETABLES. dant, and impregnated the vegetable tissue. When the Avater of composition, or that which avus in combination with the A'egetable, begins to rise, it carries along with it a small quantity of oil, which colours it; and some portions of a weak acid, afforded by the mucilage and other principles with Avhich it existed in the saponace- ous state. The phlegm likewise very often contains a small quantity of ammoniac : and this alkali appears to be formed in the operation itself; for there are feAV plants Avhich contain it in their natural state. 2. To the phlegm succeeds an oily principle, little co- loured at first; but in proportion as the distillation ad- vances, the oil which rises is thicker, and more coloured. They are all characterized by a smell of burning, and an acriel taste, that arise from the impression of the fire it- self. These oils are most of them resinous, and the ni- tric acid easily inflames them. They may be rendered more fluid and volatile by repeated distillations. 3. In proportion as the oil comes over, there sometimes distils carbonate of ammoniac, Avhich attaches itself to the sides of the vessels. It is usually soiled Avith an oil AA'hich colours it. This salt does not appear to exist ready form- ed in vegetables. Rouelie the younger proved that the plants Avhich afford the most of it, such as the cruciferous plants, do not contain it in their natural state. It is there- fore found Avhen its component parts are volatilized and reunited by the distillation. 4. All vegetables afford a very great quantity of gas by distillation ; and their nature has an influence on the gase- ous substances they afford. Those plants which abound Avith resin, afford much more hydrogenous gas; Avhile such as abound with mucilage produce carbonic acid. The mixture of these gases forms an air which is hea- A'ier than the common inflammable air, on AA'hich account it has been found very little adapted to aerostatic experi- ments. The art of charring Avood, or converting it into char- coal, is an operation nearly similar to the distillation Ave have just described. It consists in forming pyramids of Avood, or cones truncated at their summit. The whole is covered Avith earth, well beaten, leaving a lower and up- per aperture. The mass is then set on fire; and when the PROPERTIES OF CHARCOAL. 31V Avhole is well ignited, the combustion is stoppeel by clos- ing the apertures through Avhich the current of air passed. By this means the water, the oil, and ail the principles of the vegetable, are dissipated, except the fibre. The Avood in this operation loses three-fourths of its weight, and one-fourth of its bulk. According to Fontana and Morozzo, it absorbs air and water as it cools. I am assured, from my experiments in the large way, that pit- coal desulphura cd (coaked) acquires twenty-five pounds of Avater in the quintal by cooling; but the coal of wood did not appear to me to absorb more than fifteen or twen- ty. The suturbrand of the Icelanders is nothing but wood converted into charcoal by the lava which has sur- rounded it.—See Von Troil's Letters on Iceland. The charcoal which is the residue of all these distilla- tions, is a substance Avhich deserves an attention more particularly because it enters into the composition of ma- ny bodies, and bears a very great part in their pheno- mena. Charcoal is the vegetable fibre very slightly changed. It most commonly preserves the form of the vegetable which afforded it. The primitive texture is not only dis- tinguishable, but serves likewise to indicate the state and nature of the vegetable Avhich has afforded it. It is some- times hard, sonorous, and brittle; sometimes light,spongy, and friable; and some substances afford it in a subtile poAvder, Avithout consistence. The coal of oils and resins is of this nature. Charcoal well made has neither smell nor taste ; and it is one of the most indecomposable substances Ave are ac- quainted with. When dry, it is not changed by distillation in close vessels. But, when moist, it affords hydrogenous gas and carbonic acid; which proves the decomposition of the Ava- ter, and the combination of one of its principles Avith the charcoal, Avhile the other is dissipated. By successively moistening and distilling charcoal, it may be totally de- stroyed. Charcoal combines Avith oxigene, and forms the carbo- nic acid; but this combination does not take place unless their action be assisted by heat. The charcoal which burns in a chafing-dish exhibits this result; and Ave per- «>18 PROPERTIES OF CHARCOAL. ceive tAvo very immediate effects in this operation:—1. A disengagement of heat, afforded by the transition of the oxigenous gas to the concrete state. 2. A production of carbonic acid : it is the formation of this acid gas Aviiich renders it dangerous to burn charcoal in places w here the current of air is not sufficiently rapid to carry off the car- bonic acid as it is formed. Well-maele charcoal does not change by boiling in wa- ter. In process of time it gives a slight reddish tinge to that fluid, which arises from the solution of the coaly re- sidue of the oils of the a egetable mixed with the coaly residue of the fibre. If the sulphuric acid be digested upon charcoal, it is decomposed; and affords carbonic acid, sulphureous acid, and sulphur. The nitric acid, Avhen concentrated, is decomposed with much greater rapidity ; for if it be poured upon very >eiry powder of charcoal, it sets it on fire. This inflamma- tion may be facilitated by heating the chircoal or the acid. If the fluid Avhich arises in this experiment be collected,- it is found to be carbonic acid, nitrous gas, and nitric acid. M. Proust has observed, that when the acid is poureel into the middle of the charcoal, it does not take fire ; but that this effect immediately succeeds if the acid be suffered to Aoav beneath the coal. It may even be in- flamed by throAving it upon the nitric acid slightly heated. If weak nitric acid be digested upon charcoal, it dis- solves it, assumes a red colour, becomes past)-, and acs quires a bitter disagreeable taste. Charcoal, mixed Avith the sulphuric and nitric salts, de- composes them ; Avhen combined Avith oxides, it revives the metals. All these effects depend on its very great af- finity with the oxigene contained in these bodies. It is used to facilitate the decomposition of salt-petre in some cases, as in die composition of gun-powder, the black flux, &c. Rouclle has observed that the fixed alkali dissolves a good quantity of charcoal by fusion. The same chemist has discovered that the sulphure of alkali dissolves it in the humid as aacII as the dry way. Charcoal is likewise capable of combining with metals, It combines with iron in its first fusion, and mixes Avith INFUSION OF VEGETABLES. 319 it likewise in the cementation by which steel is formed. When combined Avith iron in a small proportion of the metal, it constitutes plumbago. It is likeAvise capable of combining with tin byccTnentation; to which metal it gives brilliancy and hardness, as I find by experiment. CHAP. II. Concerning the Action of Water singly applied to Vege-. tables. E may consider the action of water upon vegeta- bles in two very different points of vieAV. Ei- ther the chemist applies this fluid to the plant itself, to ex- tract and separate the juices from the ligneous part: or else the plant itself, being immersed in this fluid, is from this time delivered to its single action ; and in that situa- tion becomes gradually changed and decomposed in a pe- culiar manner. In these two cases, the products of the operations are very different. In the first the ligneous texture remains untouched, and the juices which are se- parated remain unchanged in the fluid : in the second, more especially when vegetables ferment in heaps, the na- ture of the juices is partly changed, but the oils and re- sins remain confounded with the ligneous tissue; so that the result is a mass in which the disorganized vegetable is seen in a state of mixture and confusion of the various principles which compose it. The chemist applies Avater to vegetables, to extract their juices, according to two methods, which constitute infu- sion and decoction. Infusion is performed by pouring upon a vegetable a sufficient quantity of hot water to dissolve all its principles. The temperature of the water must be varied according to the nature of the plant. If its texture be delicate, or the aroma very fugacious, the water must be slightly heat- ed ; but boiling Avater may be used Avhen the texture is w 320 VEGETABLE EXTRACTS. hard and solid, and more especially Avhen the plant has no smell. Decoction, Avhich consists in boiling water Avith the ve- getable, ought not to be employed but Avith hard and ino- dorous plants. This method is rejected by many che- mists ; because they affirm that, by thus tormenting the plant, a considerable quantity of fibrous matter becomes mixed Avith the juices. Decoction is generally banished from the treatment of odorant plants, because it dissipates the volatile oil and aroma. The decoction used in our kitchens to prepare leguminous plants for fooel, has the in- convenience of extracting all the nutritive parts, and leaving only die fibrous parenchyma. Hence arises the advantage of the American pot or boiler in ay inch the garden-stuff is boiled by simple vapour, and consequently the nutritive principle remains in the Aegetable ; to Avhich advantage avc may adel that of using any water whatever, because the steam alone is applied to the intended purpose. But die infusion, decoction, and clarification of juices, is not left to the choice of the chemist, Avhen it is re- quired to prepare any medicine; for these methods pro- duce surprising varieties in the virtue of remedies. Thus, for example, according to Storck, the concentrated juice of hemlock has no good qualities unless it be evaporated Avithout being clarified. In treating juniper berries by infusion, and evaporation on a Avater bath to the consistence of honey, an aromatic extract is obtained, of a saccharine colour : the decoction of the same berries affords a less fragrant and less resinous extract, because the resin separates from the oil, and falls down. The extract of grapes, which is called resin6in France, and most sweetmeats, are prepared in this way. ExU'acts are preparetl in the large way for sale by the assistance of AA'ater. We shall confine ourselves to speak of two only, the juice of liquorice and of cachou. The first Avill afford an example of decoction, and the second of infusion. The extract of liquorice is prepared in Spain by decoc- tion of the shrub of the same name. This plant grows abundantly near our ponds ; and avc might at a small ex- pence avail ourselves of this species of industry : I have FORMATION OF PIT-COAL. 321 ascertained that a pound of this root affords two or three ounces of good extract. The apothecaries afterwards pre- pare it in various ways for their several purposes, anel to render its use more convenient and agreeable. The cachou is extracted in the East-Indies from an in- fusion of the seeds of a kind of palm. While the seed is yet green, it is cut, infused in hot Avater ; and this in- fusion is evaporated to the consistence of an extract, which is aftenvards made into lumps, and dried in the suu. M. de Jussieu communicated to the Academy, in the year 1720, remarks by Avhich he ascertains that the differences in the several kinds of cachou arise from the A'arious de- grees of maturity in the seeds, and the greater or less quickness Avith which the extract is dried. The cachou of commerce is usually impure; but it may be cleared of its impurities by dissolving, filtering, and evaporating it several times. The taste of cachou is bitter and astringent. It dis- solves very well in the mouth, and is used as a restorative for weak stomachs : it is made into comfits by the addi- tion of three parts of sugar, and a sufficient quantity of gum adragant. When vegetables are immersed in water, their texture becomes relaxed; all the soluble principles are carried off; and there remains only the fibrous part disorgan- ized, and impregnated with vegetable oil, altered ' and hardened by the reaction of other principles., This tran- sition may be very Avell observed in marshes, where plants grow and perish in great numbers, forming mud by their decomposition. These strata of decomposed vegetables, when taken out of the Avater and dried, may be used as the material of combustion. The smell is unAA'holesome; but in shops, or places Avhere the chimneys draw well, this combustible may be used. Vegetables have been considered as the cause of the formation of pit-coal; but a feAV forests being buried in the earth are not sufficient to form the mountains of coal which exist in its bowels. A greater cause, more pro- portioned to the magnitude of the effect, is required; and Ave find it only iri that prodigious quantity of vege- tables which groAV in the seas, and is still increased bv Vol. II. S s 322 FORMATION OF PIT-OOAL. the immense mass cr those Avhich are carried doAvn by rivers. These vegetables, carried away by the currents, are agitated, heaped together, and broken by the awivcs ; and afterwards become covered Avith strata of argillaceous or calcareous earth, and are elecomposed. It is easier to conceive how these masses of vegetables may form strata of coal, than that the remains of shells should form the greater part of the globe. The direct proofs Avhich may be given of the truth of this theory are— 1. The presence of vegetables in cfi&l mines. The bamboo and bannana trees are found in1" the coal of Alais. It is common to find terrestrial ve^&ables con- founded with marine plants. 2. The prints of shells anei of fish are likewise found in the strata of coal, and not unfrequently shells them- selves. The pit-coal of Orsan and that of Saint-Esprit contain a prodigious number. 3. It is evidently seen, by the nature of the mountains Avhich contain charcoal, that their formation has been sub- marine ; for they all consist either of schistus, or grit, or limestone. The seconeUiry schistus is a kind of coal in Avhich the earthy principle predominates over the bitu- minous. Sometimes even this schistus is combustible, as is seen in that of St. George near Milhaud. The tex- ture of the vegetables, and the impression of fish, are very Avell preserved in the schistus. The origin of the schistus is therefore submarine; and consequently so likeAvise must be the origin of the coal distributed in stra- ta through its thickness. The grit-stone consists of sand heaped together, car- ried into the sea by the rivers, and thrown up against the shores by the waves. The strata of bitumen Avhich are found in these cannot therefore but come from the sea. Calcareous earth rarely contains strata of coal, but is merely impregnated Avith it, as at St. Ambroise, at Ser- vas, &c. where the bitumen forms a cement Avith the calcareous earth. FORMATION OF PIT-GOAL. 323 Concerning Pit-Coal.* Pit-coal is usually found in strata in the earth, almost always in mountains of schistus or grit. It is the pro- perty of coal to burn Avith flame, and the emission, of much smoke. -\ * A peculiar kind of co 1 is found in immense quantities, in Penn- sylvania, in the county of Northampton, near the river Lehigh It is of a shining black colour, and stains the hands very little, its fragments are tabular, as may be Seen, particularly after it has been submitted to heat. Its specific gravity is 1,6 81. It burns with very little flame, and no smoke, is with some difficulty kindled, and requires a considerable draught of air, to keep up its eombustion. When perfectly consumed, it leaves behind a small portion of white siliceous earth, containing no potash, and sometimes coloured brown, by means of iron. It does not contain any sul- phur. Neither the sulphuric, nitric, nor muriatic acids act upon it. It does not take fire, when reduced to an impalpable powder, and passed through the flame of a candle. A piece of it red hot, containing about eight cubic inches, was placed in forty-eight ounce measures of atmospheric air over water, and suffered to cool. Upon passing one measure of this air over lime water, in the Eudiometer of Montana, it gave one per cent, of carbonic acid gas The remainder of the air, after being freed from the fixed air, was reduced in purity from 100 to 85. One cubic inch of it, red hot, suspended in ten ounce measures of oxigene gas, brightened very little. The focus of an eleven-and-a-half inch lens, was directed upon a lump of it, confined in a bell-glass, in twelve ounce measures of oxigene gas, over water, when it burnt with a considerable flame, and nearly in the same manner, as the James's river coal, when a blast of atmospheric air is thrown upon it. The gas was afterwards reduced in purity, and contained fifty per cent, of carbonic acid gas. A quantity of the coal red hot, being extinguished under wa- ter, produced an inflammable air, without any mixture of fixed air. Two measures of this gas, and one of oxigene air exploded by the electric spark, in the Eudiometer of Volta, left behind one measure of 1 This is by no means the case, as the coal described above burns with little flame, and no smoke.—4m. Ed. 324 FORMATION OF PIT-COAL. The secondary schistus is the basis of all pit-coal, and the quality of the coal mostly depends upon the pro- portion of this basis. When the schistus predo- minates, the coal is heavy, and leaves a very abun- hydrogen gas, containing ten per cent of carbonic acid gas. Two measures of each of the uases, by the same means were reduced to something more than a measure of oxigene air, which \sas mixed with fifteen per cent, of fixed air. Four ounces of it, reduced to a coarse powder, were exposed in an earthen retort- to a red heat in one of Lewis's black lead furnaces, Avhen it yielded three hundred and sixty ounce measures of hydro- gen gas, of the same kind as that produced by extinguishing it, when red hot, under water The same coal taken from the retort, and sprinkled with water, and exposed a second time to heat, aftbrded thirty ounce measures of inflammable air, in the first portions of which, the carbonic acid was barely perceptible. The steam of water was transmitted over the coal red hot, confined in a porcelain tube- and it gave hydrogene gas in torrents,mixed with ten per cent, of fixed air. Two measures of this hydrogene gas, after the carbonic acid had been separated from it, ^and one of oxigene gas, exploded in the eudiometer of solta left near a mea- sure of inflammable air, mixed uith fifty per cent, of fixed air. A fire was kindled at half past eleven o'clock, by placing a quan- tity of the Eeiugh coal, upon a stratum of common charcoal in a powerful air furnace, which was then filled with equal portions of the two substances. As fast as the charcoal consumed, the Northampton coal was added, and at half past one, the furnace was completely filled with it, and two-thirds of it red hot. At four the coal was half consumed, and it continued burning until eleven o'clock at night. Five of Wedgwood's thermometer pieces, put in crucibles made of po.celain, were deposited in different places among the coal, that thev mi ht descend in different directions, and some of them be ex- posed to the greatest degree of heat. When they were cool, being measured by the guage, they gave 70, 77, 150, 156. and 159, degrees. , 125 is the hi hest heat Mr. Wedgwood could ever produce, in a common smith's forge, and 160 in an air furnace, eight inches square. Erass melts at twenty-one, copper at twenty-seven, silver at twenty-eight gold at thirty-two, and cast iron at one hundred and thirty of this thermometer. The welding heat of iron is one hundred and twenty-five* James's river coal, submitted to an experiment of the same kind, burned out in four hours. * Description and use of a thermometer for measuring the higher degrees of heat, by ro?iah Wedgwood. Phil. Trans. Vol. 72nd. FORMATION OF PIT-COAL. 325 dant earth)' residue after its combustion. This kind of coal is veined internally with flat pieces, or radier separate masses, of schistus nearly pure, Avhich Ave call fiches. As the formation of the pyrites, as well as that of coal, arises from the decomposition of vegetable and ani- mal substances, all pit-coal is more or less pyritous ; so that Ave may consider pit-coal as a mixture of pyrites, schistus, and bitumen. The different qualities of coal A lire was made with the Lehigh coal, in a Smith's forge, and two thick bars of iron were placed in it, and welded with great ease, by the proprietor of the furnace. The Smith, his journeymen, and bystanders were convinced, that the heat was much cleaner and greater, than that of the James's river coal. As the Virginia coal burns with flame and much smoke, avast por- tion of this combustible substance, and the heat generated by it, is lost by passing up the chimney. It appears from some of these experiments, that this coal does not unite to the base of oxigene gas, with as much rapidity as com- mon charcoal, and that it decomposes water. Its flame consisting of oxide of carbone, or carbonated hydrogene gas arises from this de- composition. When it is exposed to a red heat, and contains little water, it gives rise to a peculiar species of inflammable air, without any fixed air ; but when the steam of water is transmitted over it, in a red heat, the production of carbonic acid gas is very considerable, and when the hydrogene gas, thus obtained, is fired with oxigene gas, the fixed air generated amounts to thirty-five per cent, more than when it is procured from coal united to a small quantity ol water. According to the opinions, now generally adopted by the Philosophers of Europe, the gases, when little water is mix- ed with the coal, must consist of oxide of carbone and carbonated hydrogene gas. It will be said, the oxigene of the water, unites to part of the coal, and forms oxide of carbone, while its hydrogene escapes, dissolves a portion of the coal, and makes carbonated hydro- gene gas. This explanation is far from being satisfactory ; for no oxide of carbone can be detected in the gases, produced by extinguishing this coal when red hot under water, or by submitting it to a heat in an earthen retort. The Eejiigh coal promises to be particularly useful, where a long continued heat is necessary, as in distilling, or in evaporating large quantities of water from various substances; in the melting of metals, or in subliming of salts ; in generating steam to work steam engines; and in common life, for washing, cooking, inc.provided the fi) e-p/accs are instructed in such a manner, as to keep up a strong draught of dr.—Am. Ed. 32(3 FORMATION OF PIT-COAL. arise therefore from the difference in the proportions of these principles. When the pyrites is very abundant, the coal exhibits yellow veins of the mineral, Avhich are decomposeel as soon as they come in contact Avith the air ; and form an efflorescence of sulphate of magnesia, of iron, of alu- mine, &c. When pyritous coal is set on fire, it emits an insup- portable smell of sulphur; but when the combustion is insensible, inflammation is frequently produced by the decomposition of the pyrites; and it is this Avhich occa- sions the inflammation of several veins of coal. There are veins of coal on fire at St. Etienne in Forez, at Crarhsac in Rouergue, at Roquecremade in the diocese of Beziers; and it is not rare to see the fire destroy consi- derable masses of pyritous coal, Avhen the decomposi- tion is favoured by the concurrence of air and water. If the inflammation be excited in more considerable mas- ses of bitumen, the effects are then more striking; and it is to a cause of this nature that we ought to refer the origin and effect of A'olcanos. When the schistus, or slaty principle, predominates in coals, they are then of a bad quality, because their ear- thy residue is more considerable. The best coal is that in Avhich the bituminous principle is the most abundant, and exempt from all impurity. This coal SAvells up Avhen it burns, and the fragments ad- here together: it is more particularly upon this quality that the practice of the operation called desulphurating or purifying of coal depends. This operation is analogous to that in AA'hich Avood is converted into charcoal. In the desulphuration, pyramids are made, Avhich are set on fire at the centre. When the heat has strongly penetrated the mass, and the flame issues out of the sides, it is then co- vered Avith moist earth; the combustion is suffocated, the bitumen is dissipated in smoke, and there remains only a light spongy coal, Avhich attracts the air and humidity, and exhibits the same phenomena in its combustion as the coal of Avood. When it is Avell made, it gives neither flame nor smoke; but it produces a stronger heat than than that of an equal mass of native coal. This PROPERTIES OF PIT COAL. 327 operation received the name of desulphurating (desou- frage) from a notion that the coal was by this means de- prived of its sulphur ; but it has been proved that all coals which are capable of this operation, contain scarcely any sulphur. It was for a long time supposed that the smell of pit- coal Avas unwholesome; but the contrary is now prov- ed. Mr. Venel has made many experiments on this subject, and is convinced that neither man nor ani- mals are incommoded by this vapour. Mr. Hoffman relates that disorders of the lungs are unknoAvn in the vil- lages of Germany, where this combustible only is used. I think that coal of a good quality does not emit any dan- gerous vapour : but when it is pyritous its smell cannot but be hurtful. The use of coal is generally applicable to the arts; and nature appears to have concealed these magazines of com- bustible matter, to give us time to repair our exhausted forests. These mines are very abundant and numerous in the kingdom of France. Our province contains many, and we have more than twenty Avhich are in full work. Pit-coal is applied in England even to domestic uses, and this part of mineralogy is very much cultivated in that kingdom. Individuals have there undertaken the most considerable enterprizes in this way. The Duke of Bridge water has made a canal, at Bridge water, tAvo diou- sand five hundred toises in length, to facilitate the Avorking of the coal mines in Lancashire. It cost five millions of livres: part of it is carried under a mountain; and it pass- es successively under as well us over rivers and highways. In our province we are in Avant of roads only for the trans- portation of our coal; and Languedoc has not had the spirit to perform a Avork which a private individual has ex- ecuteel in England. In Scotland, Lord Dundonald has erected furnaces in which the bitumen is disengaged from coal; and the va- pours are received and conelensed in chambers, over Avhich he has caused a river to Aoav for the purpose of cooling them. These condensed vapours supply the En- glish navy Avith as much tar as it requires. Becher, in his work intitled " Foolish Wisdom, or Wise Folly," 328 MINERAL COMBUSTIBLES. printed at Frankford in 1683, affirms that he succeeded in appropriating the bad turf of Holland, and the bad coal of England, to the common uses. He adds that he ob- tained tar superior to that of SAveden by a process similar to that of the SAvedes. He affirms that he had made this known in England, and sheAATi it to the King. Mr. Faujas has carried the process of the Scotch no- bleman into execution at Paris. The Avhole consists in setting fire to the coal, and extinguishing it at the proper time, that the vapour may pass into chambers containing Avater for the purpose of condensing them. This tar ap- peared to be superior to that of Avood. Pit-coal likeAvise aflbrels ammoniac by distillation, which is dissolved in water, while the oil floats aboAe. When coal is deprived by combustion of all the oil and other volatile principles, the earthy residue contains the sulphates of alumine, iron, magnesia, lime, &.c. These salts are all formed Avhen the combustion is slow; but when it is rapid the sulphur is dissipated, and there re- main only the aluminous, magnesian, calcareous, and other earths. The alumine most commonly predominates. Naptha, petroleum, mineral pitch, and asphaltes, are only slight modifications of the bituminous oil so abun- dant in pit-coal. This oil, which the simple heat of the decomposition of the pyrites is sufficient to disengage from the coal, receives other modifications by the impression of the external air. Petroleum, or the oil petrol, is the first alteration. This oil is found near volcanos, in the vicinity of coal mines, Sec- We are acquainted Avith several springs of this pe- troleum. There is one at Gabian in the diocese of Be- ziers. It is carrieel out by the Avater of a spring Avhich issues from the lower part of. a mountain Avhose summit is volcanized. The smell of petroleum is disagreeable : its colour is reddish ; but it may be rendered clear by distilling it from the clay of Mim-iel. Naptha is mere!} a a ariety of petroleum. Near Derbens, on the Caspian Sea, there are springs of naptha, Avhich Kempfer visited about a century ago, and of which'he has left a description. MINERAL COMBUSTIBLES. 329 There is a place known by the name of the Perpetual Fire, Avhere the fire burns without ceasing. The Indians do not attribute the origin of this inextinguishable fire to naptha ; but they maintain that God has confined the De vil in this place, to deliver man from him. They go in pilgrimage thither, and make their prayers to God that he will not suffer this enemy of mankind to escape. The earth impregnated with naptha is calcareous, and effervesces with acids; it takes fire by the contact of any ignited body whatever. This perpetual fire is of great use to the inhabitants of Baku. They pare off the surface of this burning soil, upon which they make a heap of limestones, and cover it with the earth pared off; and in two or three clays the lime is made. The inhabitants of the village of Frogann repair to this place to cook their provisions. The Indians assemble from all parts to adore the Eter- nal Being in this place. Several temples Avere built, one of Avhich is still in existence. Near the altar there is a tube inserted in the earth, two or three feet in length; out of which issues a blue flame, mixed with red. The Indians prostrate themselves before this tube, and put themselves into attitudes which are exceedingly strange and painful. Mr. Gmelin observes that two kinds of naptha are dis- tinguished in this country; the one transparent and yel- low, which is found in a Avell. This well is covered with stones smeared with a cement of fat earth, in which the name of Kan is engraved; and no one is permitteel to break this sealed covering but those who are deputed from die Kan. Mineral pitch is likewise a modification of petroleum. It is found in Auvergne, at a place called Puits de La- pege, near Allais, in an extent of several leagues, which comprehends Servas, Saint Ambroix, Sec. The calcareous stone is impregnated with a bitumen which is softened by the heat of summer, when it flows from the rocks, and forms a very beautiful stalactites. It forms masses in the fields, and impedes the passage of carriages : the peasants use it to mark their sheep. This stone emits an abominable smell when rubbed. The epis- Tt 330 PROPERTIES OF AMBER. copal palace of Alais was paved Avith it in the time of Mr. Davejan; but it became necessarv to substitute other stone in its stead. It is asserted that mineral pitch Avas used to cement the Avails of Babylon. t Asphaltes, or bitumen Judaicum, is black, brilliant, ponderous, and very brittle. It emits a smell by friction ; and is found floating on the water of the lake Asphaltites, or the Dead Sea. The asphaltes of commerce is extracted from the mines of Annemore, and more particularly in the principality of Neufchatel. Mr. Pallas found springs of asphaltes on the banks of the Sock, in Prussia. Most naturalists consider it as amber decomposed by fire. Asphaltes liquefies on the fire, swells up, and affords flame, Avith an acrid disagreeable smoke. By distillation it affords an oil resembling petroleum. The Indians and Arabs use it instead of tar, and it is a component part of the varnish of the Chinese. YelloAV amber, karabe, or the electron of the ancients, is in yelloAv or broAvn pieces, transparent or opaque, capa- ble of a polish, becoming electric by friction, &c. It is friable and brittle. There is no substance on which the imagination of po- ets has been more exercised than this. Sophocles had af- firmed that it Avas formed in India by the tears of die sis- ters of Meleager, changed into birels, and deploring the fate of their brother; but one of the most interesting fa- bulous origins which have been attributed to it, is afford- ed by the fable of Phaeton burning the heavens and the earth, and precipitated by the thunder of Jove into the waters of Eridanus. His sisters are described weeping; and the precious tears fell into the waters Aviihout mixing with them, became solid Avithout losing their transparency, and A\'ere converted into the yellow amber so highly va- lued by the ancients.—See Bailly. Amber possesses less coaly matter than any other bitu- men. It is frequently found dispersed over strata of pyritous earth, and covered with a stratum of wood, abounding Avith a blackish bituminous matter. PROPERTIES, &C. OF AMBER. S31 It is found floating in the Baltic Sea, on the coast of Ducal Prussia; it is also found near Sistreron in Provence. No other chemical use Avas for a long time made of am- ber, than to form compositions for medicine and the arts. We are indebted to Neumann, Bourdelin, and Pott for a tolerably accurate analysis of this bitumen. The tAvo constituent principles exhibited in the analysis of amber, are the salt of amber, or succinic acid, and a bituminous oil. To extract the succinic acid, the amber is broken into small pieces, Avhich are put into a retort, and distilled Avith a suitable apparatus upon a sand-bath. When the fire is carefully managed, the products are—1. An insipid phlegm. 2. Phlegm holding a small portion of acid in solution. 3. A concrete acid salt, which attaches itself to the neck of the retort. 4. A broAvn and thick oil, which has an acid smell. The concrete salt ahvays retains a portion of oil* in its first distillation. Scheffer, in his Lessons of Chemistry, pro- poses to distil it Avith sand; Bergmann with white clay ; Pott advises solution in AA'ater, and filtration through Avhite cotton ; after which the fluid is to be evaporated, and is found to be deprived of the oil, which remains on the cot- ton. Spielmann, after Pott, proposes to distil it with the muriatic acid ; it then sublimes Avhite and pure. Bourde- lin clears it of its oil by detonation Avith nitre. This salt is prepared in the large way at Koningsberg, Avhere the shavings and chips of amber are distilled. The succinic acid has a penetrating taste, and reddens the tincture of turnsol. TAventy-four parts of cold Avater, and tAvo of boiling Avater, dissolve one of this acid. If a saturated solution of this salt be evaporated, it crystallizes in triangular prisms, whose points are truncated. Mr. De Morveau observes that its affinities are barytes, lime, alkalis, magnesia, &c. The oil of amber has an agreeable smell: it may be deprived of its colour by distillation from white clay. Rou- elle distilled it with Avater. When mixed Avith ammoniac it forms a liquid soap, known by the name of Eau de Luce. * Acide in the original: doubtless by oversight. T., 332 VOLCANOS. To make eau de luce I dissolve Punic wax in alcohol, with a small quantity of oil of amber ; and on this I pour the pure ATilatile alkali, Alcohol attacks amber, and acquires a yelloAv colour. Hoffmann prepares this tincture by mixing the spirit of wine with .m alkali. The medical use of amber consists in burning it, and receiving the vapour on the diseased part. These vapours are strengthening, and remove obstructions. The oil of amber is applied to the same use. A syrup of amber is made with the spirit of amber and opium, which is used to advantage as a sedative anodyne medicine. The finest pieces of amber are used to make toys. Wallerius af- firms that the most transparent pieces may be used to make mirrors, prisms, &c. It is said that the King of Prussia has a burning mirror* of amber one foot in dia- meter ; and that there is a column of amber in the cabinet of the Duke of Florence ten feet high, and of a very fine lustre. Concerning Volcanos. The combustion of those enormous masses of bitumen Avhich ar3 deposited in the bowels of the earth, produces volcanos. They owe their origin more especially to the strata of pyritous coal. The decomposition of water upon the pyrites determines the heat, and the production of a great quantity of hydrogenous gas, which exerts itself against the surrounding obstacles, and at length breaks them. This effect is the chief cause of earthquakes ; but when the concourse of air facilitates the combustion of the bitumen and the hydrogenous gas, the flame is seen to issue out of the chimneys or vents AA'hich are made : and this occasions the fire of volcanos. There are many volcanos still in an active state on our glebe, .independent of those of Italy, Avhich are the most knoAvn. The abl e Chappe has described three burning * So in the original; but the matter as well as the properties of this substance put it out of doubt that it should be lens. T. VOLCANIC PHENOMENA. 333 in Siberia. Anderson and Von Troil have described those of Iceland. Asia and Africa contain several : and Ave find the remains of these fires or volcanic products in all parts of the globe. Naturalists inform us that all the southern islands have been volcanizcd; and they are seen daily to be formed by the action of these subterraneous fires. The traces of fire exist even immediately around us. The single province of Languedoc contains more extinct volcanos than tAA>en- ty years ago Avere knoAvn to exist through all Europe. The black colour of the stones, their spongy texture, the other products of fire, and the identity of these sub- stances Avith those of the volcanos at present burning, are all in favour of the opinion that their origin Avas the same.* *A volcano was announced and described to be burning in Eanguc- doc, respecting which it is necessary to give some elucidation. This pretended volcano is known by the name of the 1 hosphorus of Ve- nejan Venejan is a village situated at the distance of a quarter of a league from the high road between St. Esprit and Bagnols. l-'rom time im- memorial, at the return of spring, a fire was seen from the high road, which increased during the summer, was gradually extin- guished in autumn, and was visible only in the night. Several per- sons had at various times directed their course from the high road, in a right line towards Venejan, to verify the fact upon the spot: but the necessity of descending into a deep valley before they could ar- rive thither, occasioned them to lose sight of the fire ; and on their arrival at Venejan no appearance was seen in the least resembling the fire of a volcano. iVJr. de Genssane describes this phenomenon, and compares it to the flashing of a strong aurora borealis : he even says that the country is volcanic. Hist. Nat. du Languedoc, Diocese de'Uzes.—At length, in the course of the last four or five years, it was observed that these fires were multiplied in the spring; and that, instead of one, there were three. Certain philosophers of Bagnols undertook the project of examining this phenomenon more closely ; and for this purpose they repaired to a spot between the high road and Venejan, armed with torches, speaking trumpets, and every other implement which they conceived to be necessary /for making their observations. At midnight, four or five of the party were deputed and directed towards the fire; and those who remained behind di- rected them constantly in their way by means of their speaking trum- pets. They at last arrived at the village, where they found three groups of women winding silk in the middle of the street by the light of a fire made of hemp stalks. All the volcanic phenomena then disappeared, and the explanation of the observations made on this subject became very simple. In the spring, the fire Mas weak, because it was fed with Avood, Avhich afforded heat and light; duf- 334 VOLCANIC PHENOMENA. When the decomposition of die pyrites is advanced, and the vapours and elastic fluids can no longer be con- tained in the boAvels of the earth, the ground is shaken, and exhibits the phenomena of earthquakes. Mephiiic vapours are multiplied on the surface of die ground, and dreadful holloAv noises are heard. In Iceland, the rivers and springs are swalloAved up: a thick smoke, mixed with sparks and lightning, is then disengaged from the crater; and naturalists have observed that, Avhen the smoke of Ve- suvius takes the form of a pine, the eruption is near at hand. To these preludes, AA^hich sheAV the internal agitation to be great, and that obstacles oppose the issue of the volca- nic matters, succeeds an eruption of stones and other pro- ducts, Avhich the lava drives before it; and lastly appears a river of lava, which Aoavs out, and spreads itself down the side of the mountain. At this period the calm is re- stored in the boAvels of the earth, and the eruption conti- nues Avithout earthquakes. The violent efforts of the in- cluded matter sometimes cause the sides of the mountain to open; and this is the cause avhich has successively formed the smaller mountains which surround volcanos. Montenuovo, which is a hundred and eighty feet high, and three thousand in breadth, Avas formed in a night. This crisis is sometimes succeeded by an eruption of ashes Avhich darken the air. These ashes are the last re- sult of the alteration of the coals; and the matter AA'hich is first throAvn out is that which the heat has half vitrified. In the year 1767, the ashes of Vesuvius AArere carried twenty leagues out to sea, and the streets of Naples Avere covered with them. The report of Dion, concerning the eruption of Vesuvius in the reign of Titus, Avherein the ashes were carried into Africa, Egypt, and Syria, seems to be fabulous. Mr. de Saussure observes that the soil of jng the summer, hemp stalks were burned because light only was wanted. At that time there were three fires, because the fair of Saint Esprit was near at hand, at which they sold their silk, and whioh consequently put them under the necessity of expediting their work. As these observers announced their arrival with much noise, the country people drove them bad; by a shower of stones which the Don Quixotes of natural history might have taken for a volcanic eruption. VOLCANIC PRODUGTSi 335 Rome is of this character, and that the famous catacombs are all made in the volcanic ashes. It must be admitted, however, that the force with wiiich all these products are throAvn, is astonishing. In the year 1769, a stone tvA'elve feet high, and four in circumference, Avas thrown to the distance of a quarter of a mile from the crater: and in the year 1771, Sir William Hamilton ob- served stones of an enormous size, Avhich employed ele- ven seconds in falling. The eruption of volcanos is frequently aqueous: the Avater, Avhich is confined, and favours the decomposition of the pyrites, is sometimes strongly throAvn out. Sea salt is found among the ejected matter, and likewise sal ammoniac. In the year 1630, a torrent of boiling AA'ater, mixed Avith lava, destroyed Portici and Torre del Greco. Hamilton saw boiling water ejected. The springs of boil- ing water in Iceland, and all the hot springs which abound at the surface of the globe, owe their heat only to the de- composition of pyrites. Some eruptions are of a muddy substance; and these form the tufa, and the puzzolano. The eruption Avhicji buried Herculaneum is of this kind. Hamilton found an anticjiie head, Avhose impression was well enough preserv- ed to ansAver the purpose of a mould. Herculaneum, at the least depth, is seventy feet under the surface of the ground, and often at one hundred and twenty. The puzzolano is of various colours. It is usually red- dish ; sometimes grey, white, or green: it frequently consists of pumice-stone in powder; but sometimes it is formed of calcined clay. One hundred parts of red puz- zolano afforded Bergmann, silex 55, alumine 20, lime 5, iron 20. When the lava is once thrown out of the crater, it rolls in large rivers down the side of the mountain to a certaim distance, which forms the currents of lava, the volcanic causeways, &c. The surface of the lava cools, and forms a solid crust, under Avhich the liquid lava Aoavs. After the eruption, this crust sometimes remains, and forms holloAV galleries, Avhich Messrs. Hamilton and Ferber have visited : it is in these hollow places that the sal ammoniac, the marine salt, and other substances, sublime. A lava may be turned out of its course by opposing banks or 336 VOLCANIC PRODUCTS. dikes against it: this was done in 1669, to save Catania; and Sir William Hamilton proposed it to the king of Na- ples, to preserve Portici. The currents of lava sometimes remain several years in cooling. Sir William Hamilton observed, in 1769, that the lava AA'hich flowed in 1766 Avas still smoking in some places. When the current of lava is received by Avater, its cool-. ing is quicker; and the mass of lava shrinks so as to be- come divided into those columns wiiich are called basaltes. The famous Giants CauseAvay is the most astonishing ef- fect of this kinel which Ave are acquainted Avith. It exhi- bits thirty thousand columns in front, and is two leagues i in length along the sea coast. These columns are be- tAveen fifteen anel sixteen inches in diameter, and from t\A*enty-five to thirty feet long. The basaltes are divided into columns of four, five, six, and seven sides. The emperor Vespasian made an entire statue, with sixteen children, out of a single column of basaltes, which he dedicated to the Nile, in die temple of Peace. Basaltes afforded Bergmann, per quintal, silex 56, alu- mine 15, lime 4, iron 25. Lava is sometimes swelled up and porous. The light- est is called pumice-stone. The substances throAvn out by volcanos are not altered by fire. They eject native substances, such as quartz, crystals of amethyst, agate, gypsum, amianthus, feld- spar, mica, shells, schorl, &c. The fire of volcanos is seldom strong enough to vitrify the matters it throAvs out. We know only of the yellow- ish capillary anel flexible glass thro\A'ii out by the volcanos of the islanel of Bourbon on the fourteenth of May 1766 (M. Commerson), and the lapis gallinaceus ejected by He- cla. Mr. Egolfrjouson, Avho is employed by the Obser- vatory at Copenhagen, has settled in Iceland, Avhere he uses a mirror of a telescope Avhich he has made out of the black agate of Iceland. The sIoav operation of time decomposes lavas, and their remains are very proper for vegetation. The fertile island of Sicily has been every where volcanizeel. I ob- serveel several, ancient volcanos at present cultivated; and VOLCANIC PRODUCTS. 337 the line which separates the other earths from the volcanic earth, constitutes the limit of A'egetation. The ground over the ruins of Pompeia is highly cultivated. Sir Wil- liam Hamilton considers subterranean fires as the great vehicle used by nature to extract virgin earth out of the boAvels of the globe, and repair the exhausted surface. The decomposition of lava is very sIoav. Strata of ve- getable earth, and pure lava, are occasionally found ap- plied one over the other; wiiich denote eruptions made at distances of time very remote from each other, since it requires nearly two thousand years before lava receives the plough. An argument has been draAvn from this pheno- menon to prove the antiquity of the globe: but the silence of the most ancient authors concerning the volcanos of our kingdom, of which Ave find such frequent traces, proves that these volcanos have been extinguished from time im- memorial ; a circumstance which carries their existence to a very distant period. Besides this, several thousand years of connected observations have not afforded any re- markable change in Vesuvius or .Etna; ncverdieless, these enormous mountains are all volcanized, and consequendy formed of strata applied one upon the other. The prodi- gy becomes much more striking, when Ave observe that all the surrounding country, to very great distances, has been thrown out of the bowels of the earth. The height of Vesuvius above the level of the sea is three thousand six hundred and fifty-nine feet; its cir- cumference thirty-four thousand four hundred and forty- four. Tiie height of Etna is ten thousand and thirty-six feet; 'and its circumference one hundred and eighty thou- sand. The various volcanic products are applicable to several uses. 1. The puzzolano is of admirable use for building in the water : when mixed with lime, it speedily fixes itself; anel water does not soften it, for it becomes continually harder and harder. I have proved that calcined ochres afford the same advantage for this purpose ; they are m; de into balls, and baked in a potter's furnace in the usual manner. The experiments made at Sette, by the com- missary of the province, prove that thev may be substi- Vol. II. Un 338 PETRIFIED VEGETABLES. tuted Avith the greatest advantage, instead of the puzzo- lano of Italy. 2. Lava is likeAvise susceptible of vitrification; and in this state it may be blown into opaque bottles of the great- est lightness, as I have done at Erepian and at Alais. The very hard lava, mixed in equal parts Avith Avood ashes and soela, produced an excellent green glass. The bot- tles made of it A\ere only half the Aveight of common bot- tles, and much stronger; as was proved by my experi- ments, and those which Mr. Jolly de Fleury ordered to be made under his administration. 3. Pumice-stone likeAvise has its uses; it is more espe- cially used to polish most bodies Avhich are someAvhat hard. It is employed in the mass or in poAArder, according to the intended purpose. Sometimes, after levigation, it is mix- ed with Avater to render it softer. CHAPTER III. Concerning the Decomposition of Vegetables in the Bow- els of the Earth. HERBACEOUS plants, buried in the earth, are slowly elecomposed; but the Avaters Avhich filter through and penetrate them relax their texture. The salts are extracted; and they become conAerted into a stratum of blackish matter, in AA'hich the vegetable texture is still discernible. These strata are sometimes perceived in dig- ging into the earth. But this alteration is infinitely more perceptible in AA-ood itself, than in herbaceous plants. The ligneous body of a tree buried under the ground be- comes of a black colour, more friable, and breaks short; the fracture is shining; and the whole mass appears, in this state, to form an uniform substance, capable of the finest polish. The A\rood thus changed is called Jet. In the environs of Montpellier, near St. Jean de Cucule, several cart loads of trunks of trees have been dug up, Avhose form A\'as perfectly preserved, but Avhich were con- '■ erted into jet. 1 have myself found a wooden peal convert- COMBUSTION OP VEGETABLES. S3V ed into jet. In the works at Nismes pieces of Avood Avere found entirely converted into the state of jet. In the neigh- bourhood of Vachery, in Gevaudan, a jet is found, in Avhich the texture of the Avalnut tree is very discernible. The tex- ture of the beech is seen in the jet of Bosrup in Scania. In Guelbre a forest of pines has been discovered buried beneath the sand; and at Beichlitz tAvo strata of coal are wrought, according to Mr. Jars, the one bituminous, and the other of fossil avooI. I preserve in the cabinet of mi- neralogy of Languedoc, several pieces of Avood Avhose ex- ternal part is in the state of jet, while the internal part still remains in the ligneous state ; so that the transition from the one to the other may be observed. Jet is capable of receiving the most perfect polish. It is made into toys, such as buttons, snuff-boxes, necklaces, and other ornaments. It is wrought in Languedoc, near Saint Colombe, at the distance of three leagues from Cas- telnaudray. It is ground doAvn, and cut into facets, by mills. Jet softens in the fire, and bums with the emission of a fetid odour. It affords an oil which is more or less black, but may be rendered colourless by repeateel distillations from the earth of Murviel. CHAPTER IV. Concerning the Action of Air and Heat upon Vege- tables. WHEN the heat is applied to a vegetable ex- posed to the air, certain phenomena are pro- duced, Avhich depend on the combination of pure air with the inflammable principles of the plant; and this is com- bustion. In order to produce a commencement, a heated body is applied to the dry wood which is intended to be set on fire. By this means the principles are volatilized in the same order as avc have pointed out in the preceding 340 COMBUSTION OF VEGETABLES. article. A smoke is produced, Avhieh is a mixture of water, oil, volatile salts, anel all die gaseous products which result from the combination of vital air with the several principles of the vegetable. The heat then in- creases by the combination of the air itself, because it passes to the concrete state: and when this heat is carried ^o a certain point, the vegetable takes fire, and the com- bustion proceeds until all the inflammable principles arc destroyed. In this operation there is an absorption of \ital air, and a production of heat and light. The combustion will be stronger in proportion as the inflammable principle is more abundant, as the aqueous principle is less abundant, as the Avood is more resinous, and as die air is purer and more conelensed. The disengagement of heat and light is more consider- able, accordingly as the combination of vital air is stronger in a given time. The resielues of combustion consist of substances which are volatilized, and fixed substances; the one forms the soot, the other ashes. The soot partly arises from substances imperfectly burn- ed, decomposed only in part, which have escaped the action of A'ital air. Hence it is that the soot may be burned over again: and hence likeAvise it is that, Avhen the combustion is Aery rapid and effectual, there is no perceptible smoke; because all the inflammable matter is then destroyed, as in the cylinder lamps, Aiolent fires, See. The analysis of soot exhibits an oil AA'hich may be ex- tracted by distillation; a resin Avhich may be taken up by alcohol, and Avhich arises either from the imperfect alteration of the resin of the A-egetable, or the combi- nation of vital air Avith the volatile oil. It likewise afforels an acid, which is often formed by the decompo- sition of mucus; and it is this acid, of great utility in the arts, for which the Academy of Stockholm has de- scribed a furnace proper for collecting it. Soot likeAvise affords volatile salts, such as die carbonate of ammoniac, and others. A slight portion of fibrous matter is likewise volatilized by the force of the fire, and aac find it again in lite soot. VEGETABLE FIRES. 341 The fixed principle remaining after combustion, forms the ashes. They contain salts, earths, and metals, of which we have already treated. The salts are fixed alkalis, sulphates, nitrates, muriates, &c. the metals are iron, gold, manganese, &c. and the earths are alumine, lime, silex, and magnesia. CHAPTER V. Concerning the Action of Air and Water, which deter- mine a Commencement of Fermentation that se- parates the Vegetable Juices from the Ligneous Part. WHEN the decomposition of vegetables is facili- tated by the alternate action of air and Avater, their e^rganization becomes destroyed; the connexion be- tAveen the various principles is broken; the water carries away the juices; and leaves the fibrous skeleton naked, sufficiently coherent, and sufficiently abundant in certain vegetables, to be extracted in this way. Hemp is pre- pared in this manner. The abbe Rozier attributes the advantage of Avatering to the fermentation of the mucilagi- nous part. M. Prozet has proved that hemp contains an extractive and resinous part; and that the Avatering de- stroys the former, and the second is detached almost me- chanically. It has been observed that the addition of a small quantity of alkali favours this operation. Running Avater is preferable to standing Avater; because standing water keeps up and develops a stronger fer- mentation, which attacks the ligneous part. It has been observed that flax prepared in running water is whiter and stronger than that Avhich is prepared in standing Avater. The stagnant Avater has likewise die incom'enience of emitting an unpleasant smell, pernicious to the animal 342 VEGETABLE I IRES. economy. The addition of alkali corrects and prevents diis effect. In the diocese of Loeleve, the young shoots of the Spanish genet are prepared by a very simple process. It is soAvn on the high grounds, where it is left for three years; at the end of Avhich time the sprigs or young shoots are cut, and formed into bundles, Avhich are sold from tAvelve to fifteen sous each. The first operation con- sists in crushing them witii a beetle. The folloAving day they are laid in a running stream, with stones upon them, to prevent their being washed away. In the evening they are taken out, and laid in a heap on the banks of the river, upon straAv or fern, covering them Avith the same, and loading the heap with stones : this operation they call mettre a couvert. Every evening they throw Avater on the heap. At the end of eight days they open the mass; and find that the bark is easily separated from the wood. They take the packets, one after the other, and beat and rub them strongly with a flat stone, till the epidermis of the extremities is Avell cleared off, and the Avhole stem becomes white. It is then hung to dry ; and the bark which was separated from the ligneous substance, is card- ed and spun, and made into very useful cloth. The pea- sants are acquainted with no other linen for cloths, sacks, shirts, Sec. Every one prepares his own, none being made for sale. The genet, genista juncea, has likewise the advantage of affording a green food to cattle during the winter; at the same time that it supports the earth by its roots, and prevents its being carried doAvn into the valleys. The bark of the mulberry tree may be treated in the same manner. Olive de Serres has described a good process for this purpose. It is the skeleton formed by the vegetable fibre only, and deprived of all foreign matter, Avhich is used to make cloth; it is the most incorruptible principle of vegeta- tion, and when this fibre, being converted into cloth, can no longer be used as such, it is subjected to extreme di- vision, to convert it into paper. The operations for this purpose are the following:—The rags are cleaned, and Taid in AA^ater to rot; after which they are torn by hooked VEGETABLE FERMENTATION. 343 pestles moved by AAater : the second pestles under which they are made to pass, are not armed Avith hooks like the first, but merely with round nails : the third are of Avood only. By this means the rags are converted into a paste, which is attenuated still more by boiling. This paste is received in Avire moulds, drieel, and forms blotting paper. Writing paper is dipped in size, anel sometimes fflazed. CHAPTER VI. Concerning the Action of Air, of Heat, and of Watej- upon Vegetables. HEN the various juices of vegetables are diffus- ed in water, and the action of this fluid is favour- ed by the combined action of air fend heat, a decompo- sition of these juices ensues. The oxigenous gas may be considered as the first agent of fermentation: it is afford- ed either by the atmosphere, or by the Avater which is de- composed. It avus from an observation of these facts that Becher thought himself authorized to consider fermentation as a kind of combustion :—Nam combustio, seu calcinatio per fortem ignem, licet putrefactionis species, eidemque ana- loga sit—fermentauo ergo definitur, quod sit corporis den- sioris rarefactio, particularumque aerearum interpositio, ex quo concluditur debere in a'ere fieri, nee nimium frigido nee nimium calido, ne partes raribiles expellantur, in aper- totamen vase, vel tantum vacuo ut partes rarefieri queant; nam stricta closura, et vasis impletio, fermentationem tota- liter impedit."—Becher, Phys. Subst. s. i. 15, v. cap. 11, p. 313. The conditions necessary for the establishment of fer- mentation are—1. The contact of pure air. 2: A certain degree of heat. 3. A quantity of Avater more or w 344 VEGETABLE FERMENTATION. less considerable, which produces a difference in the effects. The phenomena AA'hich essentially accompany fermenta- tion are—1. The production of heat. 2. The absorption of oxigene. Fermentation may be assisted—1. By increasing the mass of fermentable matter. 2. By using a proper lea- ven. 1. By increasing the fermentable mass, the principles on Avhich the air must act are multiplied; consequently the action of this element is facilitated; more heat is therefore produced by the fixation of a greater quantity of air; and consequentiy the fermentation is promoteel by the two causes Avhich most eminently maintain it, heat anel air. 2. Tavo kinds of leaven may be distinguished. 1. Bo- dies eminently putrescible, the addition of Avhich hastens the fermentation. Those Avhich already abounel Avith ox- igene, and Avhich consequently afford a greater quantity of this principle of fermentation. This effect is produced by the inhabitants of the banks of the Rhyn, by throAving fresh meat into the vintage, to hasten the spirituous fer- mentation (Lin: e Amoenit. Acad. Dissert, de Genesi Cal- culi) : and so likeAvise the Chinese throAv excrements into a kind of beer, maele of a decoction of barley anel oat.*. And on this account it is that the acids, the neutral salts, chalk, rancid oils, and the metallic calces, &.c. hasten fer- mentation. The products of fermentation have causeel different spe- cie's to be distinguished: but this variety of effects de- pends on the variety of principles in the vegetables. When the saccharine principle predominates, the result of the fermentation is a spirituous liquor; when, on the con- trarv, the mucilage is most abundant, the product is acid ; if the gluten be one of the principles of the vegetable, there will be a production of ammoniac in the fermenta- tion : so that the same fermentable mass may undergo dif- ferent alterations, Avhich ahvays depend on the nature and resnective properties of the constituent principles, the sus- ceptibility of change, &c. Thus a saccharine liquid, af- ter having undergone the spirituous fermentation, may be subjected to the aciel fermentation, by the decomposition CONDITIONS FOR SPIRITUOUS FERMENTATION. 345 of the mucilage which had resisted the first, fermentation : but in all cases the concourse of air, water, and heat, is necessary to develop fermentation. We shall therefore confine Ourselves to the examination of these three agents: —1. On the juices extracted from vegetables, and dif- fused in water, Avhich constitutes the spirituous and acid fermentations; 2. On the vegetable itself, Avhich will lead us to the formation of vegetable mould, ochres, &c. ARTICLE I. Concerning the Spirituous Fermentation and its Pro- ducts. That fermentation is distinguished by the name of Spi- rituous, Avhich affords ardent spirit, or alcohol, as its pro- duct or result. It may be considered as a fundamental principle, diat no substances are capable of this fermentation but sac- charine bodies. Pure sugar mixed with Avater forms taf- fia, or rum, by fermentation; and we find this principle in the analysis of all the bodies which are susceptible of it. In order to develop this fermentation, there is required, 1. The access of air. 2. A degree of heat betAveen ten and fifteen of Reaumur. 3. The division and expression of the juice contained in the fruits, or in the plant. 4. A mass or volume someAvhat considerable. We will make the application of these principles to the fermentation of grapes. When these are ripe, and the saccharine principle is developed, they are then pressed, and the juice Avhich Aoavs out is received in \ressels of a proper capacity, in which the fermentation appeals, and proceeds in the following manner :—At the end of seve- ral days, and frequently after a feAV hours, according to the heat of the atmosphere, the nature of the grapes, the quantity of the liquid, and the temperature of the place in Avhich the operation is performed, a movement is pro- duced in the liquor, Avhich continually increases; the vo- lume of the fluid increases; it becomes turbid and oily ; cwrbonic acid is disengaged, Avhich fills all the unoccupied Vol. II. X x 346 SPIRITUOUS FERMENTATION. part of the vessel, and the temperature rises to the 18th degree. At the end of several days these tumultuous mo- tions subside, the mass falls, the liquor becomes clearer, and is found to be less saccharine, more odorant, and of a red colour, from the reaction of the ardent spirit upon the colouring matter of the pellicle of the grape.* The causes of an imperfect fermentation are the folloAv- ing: 1. If the heat be too little, the fermentation lan- guishes, the saccharine and oily matters are not sufficient- ly elaborated, and the Avine is unctuous and sweet. 2. If the saccharine body be not sufficiently abundant, as happens in rainy seasons, the Avine is A\reak, and the mucilage which predominates causes it to become sour by its decomposition. 3. If the juice be too watery, concentrated and boiling must is added. 4. If the saccharine principle be not sufficiently abun- dant, the defect may be remedied by the addition of su- gar. Macquer has proved that excellent wine may be made of verjuice and sugar; and Mr. De Bullion has made AA-ine at Bellejames with the verjuice of his vine rows and moist sugar. There have been many disputes to determine Avhe- ther grapes should be pressed with the stalks or without. It seems to me that this depends on the nature of the fruit. When they are highly charged with saccharine and muci- laginous matter, the stalk corrects the insipidity of the Avine by its bitter principle: but when, on the contrary, the juice is not too sweet, the stalk renders it drier, and very rough. The Avine is usually taken out of the fermenting vessels at the period when all the phenomena of fermentation have subsided. When the mass is settled, the colour of the liquor is well developed, Avhen it has become clear, and its heat has disappeared ; it is put into casks, where, by a second insensible fermentation, the wine is clarified, its * Richardson, in his Treatise on Brewing, insists much on the difference between the specific gravity of the fluid before and after fermentation, which he considers as proportional to the strength or inebriating quality of the fluid. I ennented liquors have a less spe- cific gravity than they possessed before the fermentation. This cir- cumstance well deserves the attention of the manufacturer. T. SPIRITUOUS FERMENTATION. 347 principles combine more perfectly together, and its taste and smell become more and more developed. If this fermentation be stopped or suffocated, the gase- ous principles are retaineel, and the Avine is brisker, and more of the nature of must. Becher had very proper ideas of the effects of these two fermentations. Distinguitur autem inter fermentationem apertam et clausam : in aperta potus fermentatus sanior est, sed de- bilior; in clausa non ita sanus, seel fortior: causa est quod evaporantia rarefacta corpuscula imprimis magna adhuc silvestrium spirituum copia, de cmibus antea egi- mus, retineatur et in ipsum potum se precipitet, unde vai- de cum forte m reddit. Becher, Phys. Subt. lib. 1, v, V. cap. 11, p. 313. It appears, from the interesting experiments of the Mar- quis de Bullion, that the vinous fermentation does not take place unless tartar be present. By evaporating the must of grapes, a salt is obtained, which has the appearance of tartar, and forms salt of Seig- nette with the alkali of soda. A large quantity of sugar is also obtained. For this purpose the tartar is first to be extracted; after which, the must having evaporated to the consistence of a thick syrup, is to be left for six months in a cellar. At the expiration of this time, the sugar is found in a confused state of crystallization ; and this be- ing washed with spirit of Avine, to carry off the colouring part, becomes very fine and pure. Wine deprived of its tartar ferments no more, and the fermentation is in proportion to the abundance of the tar- tar. Cream of tartar produces the same effect. It appears that these salts act only as leavens, to facili- tate the decomposition of the saccharine principle. ^ The juice of grapes is not the only vegetable fluid sus- ceptible of the spirituous fermentation. Apples contain a juice Avhich easily ferments, and pro- duces cyder. Wild apples are usually employed for this purpose. These are bruised, and the juice pressed out, which ferments, and exhibits the same phenomena as the juice of grapes. In order to have cyder fine, it is to be decanted off the lees as soon as the tumultuous fermentation has subsided, and it begins to be clear. Sometimes, in order to render SPIRITUOUS FERMENTATION. it milder, a certain quantity of the juice of apples recent ly expressed is added, Avhich produces a second ferment- ation in the cyder less strong than the first. The cyder Avhich is left to stand on the lees acquires strength by that means. Cyder affords the same products as Avine; but the brandy obtained from it has a disagreeable flavour, be- cause the mucilage, which is very abundant in the cyder, is altered by the action of the heat of distillation. But if it be cautiously distilled, it affords excellent brandy, ac- cording to the experiments of M. Darcet. The juice of the harshest kind of pears affords, by fer- mentation, a kind of cyder called Perry. Cherries likewise afford a tolerably good Avine : and a kind of brandy is obtained from them, which the Ger- mans call Kirchenwasser. In Canada the fermentation of the saccharine juice of the maple affords a very good liquor; and the Americans, by fermenting the impure syrups of sugar with two parts of water, form a liquor which affords the spirit called Taffia, or Rum by the English.* A drink called Beer, is likeAvise prepared Avith certain grain; such as Avheat, oats, and barley; but more especi- ally Avith the latter. 1. The grain is made to sprout or ve- getate, by steeping it in water, and placing it in a heap. By this means the glutinous principle is destroyed. 2. It is torrified or stoved, to stop the progress of the fermen- tation, and fit it for the mill. 3. It is sifted, to separate * Peaches, plums, papaws, blackberries, persimmons, potatoes, turnips, parsnips, carrots, pumpkins, and the stalks of young Indian* corn, Sec. all undergo the spirituous fermentation. Grain of every description affords spirits of different qualities, and in different quantities according to weight. Wlve«t weighing 60 lbs. per bushel, affords from, 8 to 12 quarts. Rye 60 10 14 Indian corn 60 10 14 Buckwheat 6 8 Oats 32 5 7 Barley 45 7 9 Speltz 60 9 l.l Rice 70 13 6* • The American distiller b) Michael Krafft, p. 04. SPIRITUOUS FFRMENTATION. 349 the sprouts or radicles. 4. It is ground into a very coarse flour, named Malt. 5. The malt is infused in hot Avater, in the mash-tub. This dissolves the sugar and the mucilage, and is called the first Avort. It is then drawn off, heated, and again poured on the malt, which forms the second wort.* 6. This infusion, or Avort, is boiled with a certain quantity of hops, Avhich commu- nicate an extractive resinous principle to it. 7. An acid leaven, or ferment, is added, and it is poured into a cooler, where it undergoes the spirituous fermentation. When the fermentation has subsided, it is stirred and put into casks, Avhere it continues to ferment, and throws off a frothy scum by the bung, Avhich becomes sour, and serves as a ferment for future brewings, under the name of Yeast. The product of all the substances is a liquor more or less coloured, capable of affording ardent spirit, by distillation, of an aromatic and resinous smell, a penetrating hot taste, which stimulates the action of the fibres. Wine is an excellent drink, and is also used as die vehicle of certain medicines. Such are—1. The emetic wine, which is prepared by digesting two pounds of good white wine on four ounces of the cro- cus metallorum : 2. Chalybeated wine, made by digest- ing one ounce of steel filings in Uvo pounds of Avhite wine: 3. The Avines in which plants are infused; such as worrmvood, sorrel, and the liquid laudanum of Sy- denham, which is made by digesting for several days two ounces of sliced opium, one ounce of saffron, one dram of pounded ciimamon and of cloves, in one pound of Spanish wine. We shall proceed to examine the constituent princi- ples of these spirituous liquors, by taking that of grape*, for an example. The moment the wine is in the cask, a kind of analysis takes place, which is announced by the separation of some of its constituent principles; such * In our breweries this practice is only used for double ales: and the strengths in other cases arc regulated by the number of times the same malt is wetted, and the time of infusion. The third mashing affords small beer. T. 350 SPIRITUOUS FERMENTATION. as the tartar Avhich is deposited at the sides, 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 con- siderable. 1. The colouring principle is of a resinous nature, and is contained in the pellicle of the grape ; and the fluid is not coloured until the wine is formed; for until then there is nothing which can dissolve it: and hence it is that Avhite wine may be made of red grapes, Avhen the juice of the grape is expressed, and the husk throAvn away. If wine be evaporated, the colouring principle re- mains in the residue, and may be extracted b) spirit of wine. Olel wines lose their colour, a pellicle being precipi- tated, AA'hich is either deposited on the sides of the bot- tles, or falls to the bottom. If Avine be exposed to the heat of the sun during the summer, the colouring matter is detached in a pellicle, Avhich falls to die bottom; Avhen the vessel is opened, the discolouring is more speedy, and it is effected in t\A*o or three days during the summer. The wine thus deprived of its colour is not perceptibly weakened. 2. "Wine is usually decomposed by distillation; and the ' first product of the operation is known by the name of Brandy. Brandies have been made since the thirteenth century; and it Avas in Languedoc Avhere this commerce first ori- ginated. Arnauld de Villeneuve appears to have been the author of this discover}'. The alembics in AA'hich wine was elistilieel consisted for a long time of a kind of boiler, surmounted Avith a long cylindric neck, very nar- row, and terminating in a hollow hemisphere, in which the vapours were condensed. To this small capital Avas adapteel a narrow tube, to convey the fluid into the ser- pentine or worm pipe. This distillatory apparatus lias been successively improved. The column has been con- siderably lo\vered; and the stills generally adopteel for the distillation of Avines in Languedoc are nearly of the folloAving forms. The body of the still is flat at bottom, and the sides rise peqienelicularly to the height of twen- DISTILLATION OF ARDENT SPIRIT. 351 ty-one inches. At this height the sides incline imvards, so as to dimmish the opening to twelve inches. This opening ends in a neck of several inches long, Avhich re- ceives the basis of a small covering called the head, Avhich approaches to the figure of an inverted cone. From the angle of the upper base of the capital, there issues a small beak, intended to receive the vapours of brandy, and transmit them into the AAorm-pipe to Avhich it is adapted. This Avorm-pipe has five or six turns, and is placed in a tub, Avhich is kept filled Avith cold Avater, to condense the vapours. The body of the still is usually surrounded by the masonry as high as the neck, and the bottom only is exposeel to the immediate action of the fire. An a*>h-hole, Avhich is too small, a fire-place large enough, and a chimney placed opposite the door of the fire- place, constitute the furnaces in Avhich these stills are fixed. The still is chargeel Avith betAveen five and six quintals of wine; the distillation is made in eight or nine hours; and from sixty to seventy-five pounds of pit-coal are con- sumed in each distillation. EA'ery judicious person must be aAvare of the imper- fection of this apparatus. Its principal faults are the fol- lowing: 1. The form of the body is such as to contain a column of wine of considerable height and little breadth, Avhich being acted on by the fire at its base, is burned at that part before the upper part is heated. 2. The contraction of the upper part renders the distillation more difficult and sIoav. In fact, this inclined part being continually struck by the air, condenses the vspours, which incessantly return into the boil- er. It likeAvise opposes the free passage of the va- pours, and forms a kind of eolipile, as Mr. Beaume has observed; so that the vapours, being compressed at diis narrow neck, react on the Avine, and oppose its further ascent. 3. The capital is not constructed in a more advanta- w cighu at a time, which were vomited up at the end of three hours and a halt The juice which he obtained Avas yelloAv, transparent, salt, bitter, and leaving very little sediment, when the bird was fasting. The gastric juice may like- wise be procured by the vomiting which is excited by ir- ritation during fasting. M. Scopoli has observed that the most fluid part only is thrown up by irritation; and that the thicker part does not quit the stomach but by the as- sistance of an emetic ML Gosse, who had long accus- tomed himself to swallow the air, which answered the purpose of an emetic with him, has availed himself of this habit to make some experiments with the gastric juice. He suspends his respiration, receives air into his mouth, and pushes it towards the pharynx with his tongue. This air, rarefied in his stomach, produces a convulsive motion, which clears it of its contents. Spallanzani has observed that eagles spontaneously emit a considerable quantity of gastric juice, when fasting in the morning. We are indebted to Reaumur and the abbe Spalianzani for very interesting experiments respecting die virtue and effects of the gastric juice in digestion. They caused ani- mals to swallow tubes of metal, perforated in various places, and filled with aliments, to examine their effects. The philosopher of Pavia used purses of thread, and bags of linen and of Avoollen. He himself Wallowed small purses filled with flesh boiled or raw, with bread masti- cated, and also in its original state, &c. and likewise smajl cylinders of Avood, five lines in length and three in dia- meter, pierced Avith holes, and covered Avith cloth. M. Gosse, availing himself of the facility Avith which he Avas able to A'omit by means of the air, lias taken all kinds of food, and examined the changes they hid under- gone, by returning them after intervals more or less re- mote from the time of deglutition. From these various experiments it follows—1. That the gastric juice reduces the aliments into an uniform magma, even out of the body, and in vitro ; and that it acts in the same manner on the stomach after death: Avhich proves that its effect is chemical, and almost independent of vj- 372 THE GASTRIC JUICE. tality. 2. That the gastic juice effects die solution of the °Hments included in tubes of metal, and consequentiy de- luded from any trituration. 3. That though there is no • trituration in membranous stomachs, this action poAAerfuI- ly assists the effect of the digestive juices in animals Avhose stomach is muscular, such as ducks, geese, pige- ons, &c. Some of these animals bred up with sufficient care that they might not swalloAV stones, have neverthe- less broken spheres and tubes of metal, blunted lancets, and rounded pieces of glass, Avhich Avere introduced into their stomachs. M. Spallanzani has ascertained that flesh included in spheres sufficiently strong to resist the muscu- lar action, Avas completely digested. 4. That the gastric juice acts by its solvent power, and not as a ferment; be- cause the ordinary and natural digestion is attended Avith no disengagement of air, nor inflation, nor heat, nor in a Avord Avith any of the phenomena of fermentation. M. Scopoli observes very Avell that nothing positive or certain can be asserted respecting the nature of the gas- tric juice. It is sometimes acid and sometimes insipid M. Brugnatelli has found in- the gastric juice of carnivor- ous birds, and some others, a disengaged acid, a resin, and an animal substance, united with a small quantity of common salt. The gastric juice of ruminating animals contains ammoniac, an extractive animal substance and common salt. In our time the phosphoric salts have been found disengaged in the gastric juice. It appears, from the observations of Messrs. Spallanzani and Gosse, that the nature of the gastric juice varies ac- cording to that of the aliments. This juice is constantly acid Avhen the diet is vegetable, The abbe Spallanzani affirms, contrary to Messrs. Brugnatelli and Carminati, that birds of prey have nc\er afforded him an acid juice; and he affirms the same of serpents, frogs, fishes, &c. In order to sheAv clearly that there is a great difference betAveen the gastric juices of various animals, it is suffi- cient to observe that the gastric juice of the kite, the fal- con, &c. does not dissolve bread, though it digests flesh meat; and that the gastric juice of the turkey, the duck, &x. has no action upon flesh, but converts the hardest grain into a pulp. PROPERTIES OF MILK. 373 Messrs. Jurine, Toggia, and Carminati, have made the most successful applications of the gastric juice in the treatment of wounds. CHAPTER II. Concerning Milk. OF all the animal humours, milk is beyond contradic- tion the least animalized. It appears to partake of the nature of chyle ; it preserves the qualities and charac- ter of the aliments; and for this reason we are induced to place it at the head of the humours of animal bodies. Milk is Separated in organs called breasts or udders; and though the class of animals with breasts exhibits the greatest analogy in the internal construction of these or- gans, yet the milk varies in the several species. In the human species it is more saccharine; in the coav, milder, or softer: the milk of the goat, and of the ass, are slight- ly astringent; and it is for this reason that they are or- dered to be token in disorders which have weakened and exhausted the human frame.* * It seems most probable that the pre-eminence still given to the milk of the ass, arises from no better reason than the loud and so- norous voice of the animal, which, by a kind of reasoning very com- mon among the ancient physicians, has led to a conclusion that the milk of such a creature must be good for the lungs. The root satyrion, the milk of the goat, and many other substances, formerly stood high in medical estimation, for reasons equally obvious and equally superficial. It must not however be denied but that, when the possessor of an exhausted constitution becomes so far obedient to advice as regularly to take asses' milk, and attend toother circum- stances of regimen, he may find himself benefited ; and the asses' milk merely as milk, substituted instead of some less friendly be- verage or food, may be entitled to a share in the general effect. T. 374 PROPERTIES OF MILK. Milk is the first food of young animals. Their weak and feeble stomachs are incapable of digesting and assi- milating aliments afforded by the earth; and nature has accordingly provided them a food more animalized, and consequently more analogous to their structure, until their increased strength permits them to use a coarser food. Hunter has observed that all the animals which disgorge to feed their young, have glands in the stomach, which are formed during the incubation, and aftenvards gradu- ally obliterated. Milk is in general of an opaque white colour, and sac- charine taste. By attending to the various alterations it undergoes Avhen left to itself, or when decomposed by chemical agents, we may arrive at a perfect knoAvledge of its nature. Milk exposed to the air is decomposed in a longer or shorter time, according to the degree of heat of the at- mosphere. But if the temperature of the atmosphere be liot, and the milk in large quantity, it may pass to the spi- rituous fermentation. Marco Polo, the Venetian, who Avrote m the thirteenth century, affirms that the Tartars drink mare's milk, so well prepared that it might be taken for Avhite AA'ine. Claude Strahelenberg reports that tlie Tartars extract a vinous spirit from milk, which they call Arki (Desciiption de l'Empire de Russie). John George Gmelin, in his Voyage to Siberia, affirms that the milk is suffered to become sour, and is afterwards distilled. M. Nicolas OseretskoAVsky of St. Petersburgh, has proA^ed—1. That milk deprived of its cream cannot pro- eluce ardent spirit, either AA'ith a ferment or without. 2. That milk agitated in a close vessel affords ardent spirit, 3. That fermented milk loses its spirituous principle by heat, and passes to the state of vinegar.—Journal de Phys. 1779. Milk becomes sour in the summer, and in three or four days the acid has required its strength. If die Avhey be then filtered, and evaporated to half, cheese is de po- sited. If it be again filtered and a small quantity of the tartareous acid be added, a quantity of small crystals of tartar are seen to be formed in the course of an hour aftenA'ards, which according to Scheele can (not) .irise only from the small quantity of muriate potash (in ACID OF MILK. 375 milk, but from an essential salt*) which milk always contain. To separate the various principles contained in sour whey, the folioAving process may be used, which was pointed out by the celebrated Scheele. Evaporate the sour milk to one eighth. All the acid separates, and remains on the filter. Pour lime water on the residue; an earth is precipitated, and the lime com- bines with the acid. The lime may be displaced by the oxalic acid, which forms with it an insoluble oxalite, Avhich falls down, and the acid of milk remains disen- gaged. The fluid is then to be evaporated to the con- sistence of honey, and upon this very pure alcohol is to be poured. The sugar of milk, and all the other princi- ples, are insoluble, except the acid. The mass being then filtered, the acid of milk may be separated from its solvent by distillation. This is the acid known by the name of Lactic Acid. It possesses the folloAving cha- racters. 1. When saturated with potash, it affords a delique- scent salt, soluble in alcohol. 2. With soda, a salt not crystallizable, and soluble in alcohol. 3. With ammoniac, a deliquescent salt, Avhich suffers most of its alkali to escape before the heat has destroyed the acid. 4. Barytes, lime, and alumine, form with it salts which are deliquescent. 5. Magnesia affords small crystals, which are resolved into a liquor. 6. Bismtith, cobalt, antimony, tin, mercury, silver, and gold, are not attacked by it either hot or cold. 7. It dissolves iron and zinc, and produces hydroge- nous gas. The solution of iron is brown, and does not afford crystals: that of zinc crystallizes. 8. With copper it assumes a blue colour, which changes to green, and aftenAards to an obscure brown, without crystallizing. * The words in the parentheses are added, to render the text con- formable to Scheek's Essay. T. 376 SUGAR OF MILK. . 9. When kept in digestion upon lead for several days, it dissolves it. The solution does not afford crystals. A light sediment of a white colour is formed, which Scheele considers as a sulphate of lead. Whey not sour contains a saline substance, known by the name of Sugar of Milk. Messrs. Valgamoz and Lichtenstein have described the process used to obtain this saline substance. The milk is deprived of its cream in the usual manner, and of its curd by rennet. It is then concentrated by evaporation till it has acquired the consistence of honey, after which it is put into moulds, and dried in the sun. This is called Sugar of Milk in cakes (sucre de lait en tablettes). These cakes are dissolved in Avater, clarified Avith Avhite of egg, evaporated to the consistence of syrup, and set to crystallize in a cool place. It affords white crystals in rhomboidal parallelopi- pedons. Sugar of milk has a slightly saccharine taste, insipid, and as it were earthy. It is soluble in three or four pints* of hot water. Mr. Rouelle obtained from tAventy-four to thirty grains- of ashes from one pound of this salt burned. Three-fourths consisted of muriate of potash, and the rest was carbonate of potash. Sugar of milk exhibits the same appearance as sugar, either by distillation, or on the fire. This salt,f treat- ed with ihe nitric acid, afforded me three gross of oxalic acid in the month of July, 1787 (Memoire presente a la Societe Royale des Sciences de Montpellier J. Scheele observed the same fact nearly at the same time. I ob- tained it in beautiful crystals; Scheele, in the form of a white po\A'der4 * By an oversight for parts. "t The quantity of salt used is not put doAvn. Scheele obtained five drachms of acid of sugar in long crystals, by distilling nitrous acid from twelve ounces of sugar of milk and seven drachms and a half of the peculiar acid of sugar of milk in a white powder. The memoir of Scheele is dated 1780. T. \ I do not see by what oversight it is that our ingenious author seems to confuse the two salts together, which are afforded by treating the sugar of milk with nitrous acid. One, as observed in the preceding note, is the oxalic or saccharine acid, and the other DECOMPOSITION OF MILK. 377 If six spoonfuls of good alcohol be mixed Avith three pints of milk, and the mixture be exposed to heat in close vessels, with the attention to give, from time to time, a slight vent to the gas of the fermentation; the milk is found, in the course of a month, to be changed into good acetous acid, according to Scheele. If a bottle be filled Avith fresh milk, and inverted be- neath the surface of milk in an open vessel, and this be subjected to a degree of heat a little exceeding that of summer, at the end of tAventy-four hours the milk is found to be coagulated; the gas which is eleveloped displaces the milk : a proof according to Scheele, that the vinous fermentation has token place. To decompose milk, anel separate its various constitu- ent parts, rennet, or the milk turned sour in the stomach of calves, is commonly maele use of. For this purpose the milk is warmed, and tAvelve or fifteen grains of rennet is aelded to each pint. Gallium, the floAvers of thistle or artichokes, and the internal membrane of the stomach of birds dried, and reduced to powder, &c. are among the substances Avhich may be used to turn milk. The whey obtained in this manner is turbid; but may be cla- the acid of sugar of milk. The properties of this last (Scheelc's Essays, London, !786) are the following : 1. It is combustible like oil in a red hot crucible, without leaving any mark of ashes behind. 2. Sixty parts of boiling water, or eighty of cold water, are required to dissolve it. 3. Its taste is sourish, it reddens tincture of litmus, and effervesces with chalk. 4. By des- tructive distillation it melts, grows black, froths very much ; a brown salt, smelling like a mixture of flowers of benzoin and acid of amber, sublimes; a brown liquid without any appearance of oil, conies over into the receiver, and is found to contain some of the same kind of salt as was sublimed. The sublimed salt is acid, easily soluble in ardent spirit, but more difficultly in water, and burns in the fire with a flame. 5. With all the soluble earths it forms salts insoluble in wa- ter! 6. With vegetable alkali it forms a perfectly neutral crystalliza- ble salt, soluble in eight times its weight of boiling water, and sepa- rable for the most part by cooling. 7. With mineral alkali it forms a salt which requires only five parts of boiling water for its solution. 8. With volatile alkali it forms a salt which, after being gently dried, has a sourish taste.T 9. It does not perceptibly acton the metals; but forms, with their calces, salts of very difficult solubility, which therefore fall down. T. Voi.. II. °> B 378 COAGULATION OF MILK. rifled by boiling it Avith Avhite of egg, and subsequent fil- tration. On the mountain of Larzac I haA'e seen the dairy avo- man plunge her arms up to the elboAvs in the milk, and change their place from time to time. This a\ as done Avith a vieAv to hasten the separation of the prin- ciples ; and it is probable that the heat, and perhaps cer- tain emanations from the arm itself, might favour that effect. The solid mass which separates from \\ hey, contains tAvo other substances very interesting to be known; name- ly, cheese and butter. If any Aegetable or mineral acid be put into milk, a coa- gulation follows, as is Avell known. The only difference is, that the mineral acid affords less cheese or curd than the vegetable; and the various substances used to coagu- late milk, may perhaps act merely by virtue of the acid they contain. Olaus Borrichius obtained no acid from curdled milk at a degree of heat incapable of decomposing it. The coagulum a\ hich is afforded in all these cases, contains a substance of the nature of gluten, Avhich forms the cheese; and another substance of the nature of oils, which forms the butter. When cheese is prepareel for the table, the butter is not separated, because it renders it milder and more agreeable. The caustic alkalis dissolve cheese by the assistance of heat. But it is not held in solution by an alkali in milk. If one part of cheese newly separated, and not dried, be mixed with eight parts of water slightly acidulated by a mineral acid, anel the mixture be boiled, the cheese will be dissolved, though it would not have been sensibly acted by on by a vegetable acid. This is the cause why the vegetable acids separate a much greater quanti- ty of curd from the same quantity of milk than the mi- neral acids do. The cause AA'hy salts, gums, sugar, See. coagulate milk, may be deduced from the greater affinity of the water A\ith these bodies than Avith the cheese. The earth of cheese is a phosphate of lime, according to Scheele. COAQULATION OF MILK. CHEESE. 379 No substance has a stronger resemblance to cheese than the white of egg boiled. White of egg is dissolved in di- lutee! acid, and also in caustic alkali, and in lime-Avater, and is precipitated from them by acids. Scheele thinks that the coagulation of Avhite of egg, lymph, and cheese, is OAving to the combination of ca- loric ; and he proves his opinion as follows :—Mix one part of Avhite of egg Avith four parts of water; pour in a small quantity of pure alkali; add as much muriatic acid as is necessary to saturate it, and the Avhite of egg will coagulate. In this experiment there is a change of prin- ciples. The heat of the alkali combines Avith the white of egg, and the alkali Avith the muriatic acid.* Ammoniac dissolves cheese more effectually than fixed alkalis. If a feAv drops be poured into coagulateel milk, it quickly causes the coagulum to disappear. Concentrated acids likewise dissolve it. Nitric acid disengages nitrogene. The curd dried, and placed in a proper situation to un- dergo a commencement of the putrid fermentation, ac- quires consistence, taste and colour. In this state it is used at table by the name of Cheese. At Roquefort, Avhere I have attended the manipulations of the excellent cheese which is made there, care is taken to press the curd Avell, in order to expel the whey, and to dry it as accurately as possible. After this it is taken into caves, Avhere the temperature is two or three degrees above 0. The fermentation is eleveloped by a small quan- tity of salt. The putrefaction is suspended by scraping the surface from time to time ; and the fermentation tiius governed by art, and kept under by the coolness of the caves, produces a slow effect upon all the cheese, and suc- cessively develops the red and blue colours, of Avhich I * The reasoning of Scheele is more fully this:—Heat coagulates white of etcgi without diminishing its weight: whence he concludes coagulated white of egg to be a combination of heat with white of egg. Acids expel heat from caustic alkalis when they combine with them, but not from mild alkalis. A very dilute alkali is used in this experiment, that the temperature may not be raised, and neverthe- less the effect takes place ; but it docs not when a mild alkali is used. Whence he concludes that the heat of the caustic alkali, instead of being employed to raise the temperature, has entered into combina- tion with the white of egg, and coagulated it. T. 380 BUTTEll. have given the etiology in a Memoir on the Fabrication of Cheese at Roquefort, presented to the Royal Society of Agriculture, and printed in the fourth Aolume of the An- nales Chimiqucs.* Butter is the third principle contained in milk. It is separateel from the scum and the caseous matter by rapid agitation. The substance called cream is a mixture of cheese and butter which floats on the top of the milk. Violent agitation converts this into froth ; in which state it is called whipped cream. Butter has a soft consistence, is of a yellow golden co- lour more or less deep, of a mild agreeable flavour, melts easily, and becomes solid again by mere cooling. Butter is easily changed, and becomes rancid like oils. The acid AA'hich is developed may be carried off by Ava- ter, or by spirit of Avine, Avhich dissolve it. Fixed alkali dissolves butter, and forms a soap little known. Distillation affords a coloured concrete oil from butter, and a strong pungent acid. This oil, by repeated distil- lation, becomes altered, and resembles volatile oils. Milk is therefore a mixture of oil, lymph, serum, and salt. This mixture is Aveakly united, and the union be- tAA'eeii the principles is easily destroyed. Milk is said to be turned when the disunion of its principles is effected by mere repose ; but when this separation is made by re- agents, it is said to be curdled\ or coagulated. * It is in the foui h volume orthe Annale de Ciimie that the au- tli him to have the greatest analogy with the salt of ben- zoin. Mr. Fourcroy has observed that the discovery of Mr. De la Salle has been confirmed by the Royal Society of Medicine, which has received several biliary calculi that appeared to be formed' by a salt analogous to that AA'hich Avas observed by this chemist. They consist of masses of transparent crystalline plates, similar to mica or talk. The Society of Medicine possesses in its collection a gall bladder entirely filled with this saline concretion! We may, therefore, as Mr. De Fourcroy obsen'es, ad- mit of tAvo kinds of calculi: the one are opaque, and are afforded only by the condensed bile; the others consist of the crystals AA'e have described. Boerhaave observed, long since, that the gall bladder of oxen, at the end of the winter, was filled Avith calculi, but that the fresh pasturage dissipated these concretions. Soaps have been proposed as solvents for these calculi. The Academy of Dijon has published the success of a mixture of essence of turpentine and ether. Fresh ve- getables, Avhich are such sovereign remedies in destroy- ing these concretions, oAve their virtue perhaps to the cir- cumstance that they develop an acid in the stomach, as we have observed in treating of the gastric juice. The use of the bile, in the animal economy, consists, no doubt, in dividing those substances which have under- gone a first digestion in the stomach; and in giving effi- cacy and force to the motion of the intestines. When its flux is interrupted, it abounds in the blood, and the whole bodv becomes of a yellow tinge. The bile or gall is an excellent vulnerary externally ap- plied : internally taken, it is a good stomachic, and one of the best deobstruents the art of medicine possesses. This kind of remedies deserves the preference, as being more analogous to the constitution; and bile is a proper medi- cine when the digestion languishes, or the viscera of the lower belly are clogged. Bile, like other soaps, removes spots of oil, or other greasy matter, from substances to AA'hich they are ad- herent. 392 PROPERTIES OF JELLIES. CHAPTER VI. Concerning the. Sojt and White Parts of Animals. THESE parts are perhaps less known than those of which Ave have just treated; but their analysis is not less interesting: we may even affirm that it is more so; because the application of the knoAvledge we may acquire on this subject, will daily present itself in the com- monest purposes of domestic life. All the parts of animals, whether membranes, tendons, aponeuroses, cartilages, ligaments, or even the skin anel horns, contain a mucous substance very soluble in Avater, but not in alcohol, and known by the name of Jelly. No- thing need be done to obtain it, but to boil these animal substances in water, and concentrate the decoction, until by mere cooling it assumes the form of a solid tremulous mass. Jellies are very common in our kitchens : and the cooks are perfectly Avell acquainted with the methods of making them, and of giving them solidity when the temperature of the atmosphere is very hot. The jelly of harts-horn is extracted by a similar operation, and afterwareis rendered Avhite with the milk of almonds. This kind of food, dulv scented, is served up at our tables by the name of blanc manger. Jellies are in general restorative and nourishing: that of harts-horn is astringent and emollient. Jellies in general have no smell in their natural state, and their taste is insipid. By distillation they afford an in- sipid and inodorous phlegm, AA'hich easily putrefies. A stronger heat causes them to swell up, become black and emit a fetid odour accompanied with white acrid fumes. An alkaline phlegm then passes over, succeeded by an empyreumatic oil, and a little carbonate of ammoniac. A spongy coal remains, Avhich is with difficulty -reduced to ashes, anel affords by analysis muriate of soda, and phosphate of ljme. 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 formed on its surface, which speedily JELLIES. PORTABLE SOUP. 393 extend to the bottom of the pots. A large quantity of nitrogenous, hydrogenous, anel carbonic gas is emiucd. Water dissolves jellies perfectly. Hot water dissolves a large quantity, as they become consistent only by cool- ing. Acids likewise dissolve them, and alkalis more es- pecially do. ' The nitric acid disengages nitrogene gas, according to the fine experiments of M. Berthollet. When jelly has been extracted without long tlecoction, and has no lymph mixed Avith it, it then possesses most of the characters of the vegetable jelly : but it is seldom ob- tained without a mixture of lymph; anel in this case it essentially differs from the vegetable jellies, in ciffording nitrogene gas and ammoniac. If jelly be concenfrated to such a degree as to give it the form of a cake, it is depriveel of the property of pu- trefying ; anel by this means the dry or portable soups are formed, Avhich may be of the greatest advantage in long voyages. The following is a receipt for preparing these cakes: Calves feet 4 Leg of beef 12 pounds. Knuckle of veai 3 pounds. Leg of mutton 10 pounds. These are to be boiled in a sufficient quantity of water, anel the scum taken off as usual; after Avhich the soup is to be separated from the meat by straining anel pressure. The meat is then to be boiled a second time in other Ava- ter ; and the.two decoctions, being adeleel together, must be left to cool, in order that the fat may be exact!) sepa- rated. The soup must dien be clarified Avith five or six AA'hites of eggs, and a sufficient quantity of common salt added. The liquor is then strained through flannel, and eva- porated on the water-bath to the consistence of a very thick paste; "after Avhich it is spread rather thin upon a smooth stone,' then cut into cakes, and lastly dried in a stove un- til it becomes brittle : these cakes are kept in Avell closed bottles. The same process may be used to make a port- able soup of the flesh of poultry; and aromatic herbs mav be* used as a seasoning, if thought proper. " Vol. H. 3D 394 LELLIES. GLUES. These tablets or cakes may be kept four or five years, When intended to be used, the quantity of half an ounce is put into a large glass of boiling Avater, which is to be covered, and set upon hot ashes for a quarter of an hour, or until the Avhole is entirely dissolved. It forms an ex- cellent soup, and requires no addition, but a small quan- tity of salt. The cakes of hockiac, Avhich are prepared in China, and are knoAvn in France by the name of colle de peau d'dne, are made with animal substances. They are used in disorelers of the lungs, in the dose from half a dram to tAvo drams. The nature of the substances made use of, and die me- thoel of operating, produce some difference in these pro- ducts. Old or lean animals afford in general a better glue than the young and fat. For a full account of the art of making glue, consult VArt de faire differentes1 Especes de Colle, par M. Duhamel de Monceau, de VAcademie des Sciences. 1. To make the strong or English glue, the parings of leather, the skins of animals, with the ears of oxen, calves, sheep, &c. are used. These matters are first digested in water, to penetrate the texture of the skins ; they are af- tenvards steeped in lime Avater, taking care to stir nnd agitate them from time to time; they are then laid in a heap for some time, afterAvards Avashed, and the superabundant water pressed out by a press. These skins are then digested in Avater gradually heated to ebullition. The liquor is after- Avards poured out, and separated Avith pressure. Lastly, it is thickened by evaporation of the Avater by heat, and poured on flat polished stones or into moulds, and left to dry and harden. This glue is brittle. It is softened by heating it Avith a small quantity of water for use, and is applied with a brush. Carpenters and cabinet-makers use it to fasten pieces of Avood together. 2. The glue of Flanders is merely a diminutive* of the strong glue. It has not the same consistence, and cannot be used in glueing Avood; it is thinner and more transpa- rent than the former. It is made AA'ith a more accurate • choice of materials, and with greater care. It is used by designers. Mouth glue is made of this, to stick paper to- GLUES. ISINGLAS3. 39. gether, by fusing it again Avidi the addition of a small quantity of Avater, and four ounces of sugar-canelv to a pound of the glue. 3. The colle de gand is made Avith the clippings of white gloves, Avell steeped in Avater, and boiled: it is likeAvise made Avith the clippings of parchment. In order that these two kinds of glue may be fit for use, it is ne- cessary that they be of the consistence of a tremulous jelly when cold.* 4. Fish-glue, or isinglass, is made of the mucilaginous parts of a large fish commonly found in the Russian seas. The skin, the fins, and the nervous parts, are cut into slices, boiled on a slow fire to the consistence of jell)*, spread out to the thickness of a sheet of paper, and form- ed into cakes or long pieces, such as we receive them from Holland. The silk manufacturers, and more espe- cially the ribbon Aveavers, use it to give a lustre to their goods : it is also used to stiffen gauzes; and to clarify or fine Avine, by mixing a solution of this substance with it. Isinglass enters into the composition of some plasters, It is excellent to correct acrid humours, and terminate obstinate venereal disorders. Gilder's size 2s made by boiling eel-skins in water with a small quantity of lime: the Avater is strained off, and some whites of eggs added. When it is in- tended to be used, it is heated, applied to the surface in- tended to be gilded, and Avhen it is dry the gold leaf is laid om . 5. The glue of snails is made by exposing snails to the sun, and receiving in a glass the fluid which flows from them. This liquor is mixed Avith the juice of milk thistle. It is used to cement glasses togedier, which are aftenvards exposed to the sun to }6 To make the glue of parchment, or parchment size' two or three pounds of the clippings of parchment are put into a pail of water. These are boiled until hall the water is evaporated; after which the whole u stramcc! through a clodi, and left to settle. * These weaker glues are called Size by our workmen, Avho apply/ the name of Glue to the strong glue only. T. J(J6 MUSCULAR PAttTS The glue or size used in the paper manufactories, to fortify the paper, and to repair its defects, is made AA-ith Avheat flour diffused in boiling Avater, and strained through a sieve. This size must be used the folloAving day, and neither sooner nor later. The paper is after- wards beat Avith a mallet, sized a second time, put into the press to smooth and unite it, anel afterwards extended by hammering: CHAPTER VII. Concerning the Muscular or Fleshy Part$, THE muscles of animals are formed of longitu- dinal fibres connected togedier by the cellular membrane, and impregnated with various humours, in which we find partly those Ave have already examined separate iy. The analysis of these substances by distillation afforded ns litde instruction respecting their nature. The pro- ducts were, water Avhich easily became putrid, alkaline phlegm, ernp a reumatic oil, carbonate of ammoniac, and a coal Avhich afforded by incineration a small quantity of fixed alkali, and febrifuge salt. The process wiiich succeeds the best for separately ob- taining the various substances which compose muscles, is the following, Avhich has been pointed out to us by Mr. De Fourcroy. 1. The muscle is first washed in cold water: by this means the colouring lymph, and a saline substance, are taken up. By slow evaporation of this water, the Ivmph coagulates, and may be separated by the filter; and a continuance of the evaporation affords the saline matter. 2. The residue of the first Avash n is digested in alcohol, Avhich dissolves the extractiA-e matter, and a por- ANALYSIS OF FLESH. 3V7 tion of the salt; the extract is separated by the evapora- tion of the alcohol. 3. The residue of these first operations, is to be boiled in water, which takes up the jelly, the fat part, anel the remaining saline and extractive matters. The fat oil sAvims on die surface, and may be taken off. 4. After these operations, there remains only a Avhite insipid fibrous substance, insoluble in Avater; Avhich con- tracts by heat, like other animal substances; affords am- moniac, and very fetid oil, by distillation. Nitrogene gas is obtained from it by the nitric acid. It possesses all the characters of the fibrous part of the blood, in which fluid it is formed, to be afterwards deposited in die muscles, where it receives the last character appropriated to it. Mr. Thouvenel, to whom Ave are indebted for interest- ing researches on this subject, has found in flesh a mucous extractive substance, soluble in water and in alcohol, possessing a peculiar taste Avhich jelly has not; and Avhen this substance is very much concentrated, it assumes an acrid and bitter taste. Fire develops an aromatic flavour in it. This substance, evaporated to dryness, assumes a bitter, acrid, and saline taste. It SAvells up upon hot coals, and liquefies; emitting an acid, penetrating smell, resembling that of burned sugar. It attracts the humi- dity of the air, and forms a saline efflorescence. In a hot atmosphere it becomes sour, and putrefies. All these characters indicate a resemblance between this substance, the saponaceous extracts, and the saccharine matter of vegetables. Mr. Thouvenel, Avho has likeAvise analyzed the salt obtained by the decoction and sIoav evaporation of flesh, obtained it sometimes in the form of down, and sometimes in that of crystals, whose figure he could not describe This salt appealed to him to be a phosphate of potash in frugivorous quadrupeds, and a muriate of potash in carnivorous reptiles. It is probable, as Mr. De Fourcroy observes, that this salt is a phosphate of soda or of ammoniac, mixed with the phosphate of lime These salts are indicated, and even with excess of acid like those of urine, by lime-water and ammo- niac,' which form white precipitates m the elecoction 01 flesh. 398 ANALYSIS OF FLESH The most abundant part of muscles, and that which constitutes their predominating character, is the fibrous matter. The characters Avhich distinguish this substance are— 1. It is not soluble in Avater. 2. It affords more nitrogene gas by the nitric acid tiian other substan- ces do. 3. It afterAvards affords, the oxalic acid* and the malic acid. 4. It putrefies easily Avhen moist- ened, and affords much concrete ammoniac by distilla- tion. The other three substances contained in fleshy namely the lymph, the jelly, and the fat part, are the same sub- stances concerning Avhich Ave have already treated, under the same denominations. From these principles we may give the ethiology of the formation^ of soup, and follow the success- ive disengagement of all the principles we have spoken of. The first impression of the fire, when a soup is made, is the disengagement of a considerable scum, Avhich is" taken off until it no longer appears. This scum arises merely from the disengagement of the lymph, Avhich coagulates by the heat. It assumes, by the im- pression of the fire, a red colour, which it does not na- turally possess. At die same time the gelatinous part is disengaged, which remains dissolved in the soup, and congeals only by cooling. It forms on the surface of cold soup a body more or less thick, according to the na- ture of the substances, and the age of the animals; for young animals afford a larger quantity than such as are old. # As soon as the flesh is penetrated by heat, Hat round drops arise, and float at the surface of the fluid in which they are not aftenvards dissolved, but conceal by cooling, and exhibit all the characters of fat. In proportion as the digestion proceeds, the mucous extractive part separates; the soup becomes coloured, vsVumes its peculiar odour and taste; and it is more ANALYSIS OF FLESH. 399 particularly to this principle that its properties arc owing. The salt which is at the same time dissolved takes off the insipidity of all the before-mentioned principles: and at this period the soup is completely made. According to the nature of the several principles Avhich are disengaged, and the order in Avhich they appear, it is evident that the management of the fire is not a matter of indifference. If the ebullition be hastened, and a proper time be not alloAved for the disengagement of the mucous extractive matter, the three inodorous and insipid princi- ples are obtained; and this is observed in soups made by- cooks who are hastened, or have not time alloAA'ed to pay a due attention to their Avork. When on the contrary, the digestion is made over a sIoav fire, the principles separate one after the other, in order; the skim- ming is more accurately performed; the aromatic flavour which is disengaged combines more intimately, and the soup is of an excellent flaA'our. These are the soups of the good Avomen who perform better with a small quan- tity of meat, than professed cooks Avith their usual prodi- gality, and in this case we may say that the form is of more value than the substance. The heat must not be applied too long; for the great evaporation, by concentrating the principle of smell 'and taste, at the same time with the salt, renders them acrid and bitter. CHAPTER VIII. Concerning Urine. RINE is an excrementitious humour of the body : and it is one of the fluids of which it is of the Greatest importance to possess an accurate knowiedge; because the practical physician may derive the greatest u 400 CHARACTERS OF URINE. advantage from information of tiiis nature. , It is known to what a degree of extravagance the marvellous pretensi ons of this kind have been carried. The delirium has proceeded to such a height, as even to pretend to ascer- tain from the urine, not only the nature of the disorder, and the character of the patient, but likeAvise the sex and condition. The true physician has never given into this excess*. but he has alvrays derived assistance, in his practice, from the characters exhibiteel by the urine; and this is the hu- mour from Avhich he may draw the most satisfactory indi<- outions. It carries out, as Ave may say, the internal charac- ter ; and a physician Avho knows how to form a juelgmertt upon its properties, may deduce the most instructive con- sequences from it. Monro, in his Treatise of Compara- tive Anatomy, has described the organs which, in birds, supply the place of the kidneys : they are placed near the vertebral column; and communicate, by tAvo ducts, to the vicinity of the anus. He affirms that the urine of birds is that whitish substance which almost always accompanies the excrements. Chemical analysis ought to enlighten the physician iu his researches concerning the Urine. The nature of the principles it carries off in certain circumstances, affords vast information respecting the predominant principle in the fluids of the human body. Its various states shew the elisposition of the constitution. Persons of a very irritable habit have the urine of a lighter colour than others; gouty persons evacuate turbid urine; and it has been observed that, when the bones become soft, the urine carries off the phosphate of lime, Avhich constitutes their basis; instances of which were observed in the per- sons of Mrs. Supiot, the widoAv Melin, 8cc. The vari- ous states of any disorder are always pointed out by the state of the urine ; and the truly practical physician will there observe signs of crudity and concoction which will direct his proceedings. Urine is likewise an humour interesting to be knoAvn on account of the various uses to which it is applied in the arts. It A\ras from this substance alone that phospho- rus Avas, for a long time, extracted; it is to this fluid that \A'e OAve the development of the blue colour of turnsol, CHARACTERS AND ANALYSIS OF URINE. 401 and the violet of archil; it may be successfully employed in forming artificial nitre beds ; it powerfully contributes to the formation of sal ammoniac ; it mav be" used to r re- pare the alkali in the manufacture of Prussian blue; and, m a word, it may be applied in all the operations wherein the concurrence of an animal humour is required. Urine, in its natural state, is transparent, of a citron yellow colour, a peculiar smell, and a saline taste. It is more or less abundant, according to the seasons, and the state of the individual. It is sufficient to observe, on this subject, that transpiration, and more especially per- spiration or sAveat, supply the place of the secretion of urine; and that, consequently, a\hen the transpiration is great, the urine is not abundant. Physicians distinguish two kinds of urine. The one is emitted one or two hours after drinking ; this is aque- ous, contains scarcely any salts, and has neither colour nor smell: it is this Avhich is evacuated so plentifully during a course of mineral waters. The other is not eva- cuated until after the functions of sanguification are finish- ed ; and may be call Faeces Sanguinis. This has all die characters we have enumerated anel assigned to urine. It is carrieel by the arteries into the kidneys, Avhere it is separated, and poured into the receptacles of these organs, whence it passes, by the ureters, into the bladder; Avhere it remains a longer or shorter time according to the habi- tude of die person, the nature of the urine, the irrita- bility or magnitude of the bladder itself. The urine has been long considered as an alkaline fluid; but in our time it has been proveel to contain an excess of acid. It appears from the experiments of M. Berthollet __1. That this acid is of the nature of the phosphoric acid. 2. That the urine of gquty persons contains less of this acid; whence he conjectures, Avith reason, that this acid retained in the blood, and conveyed into tl.c ar- ticulations, produces an irritation, and consequently a flux of humours, Avhich cause pain and sAvelling. The analysis of urine by distillation has been accurately made by various chemists,* but more especially by Rou- elle the younger. Much phlegm is obtained, Avhich pu- trefies Avith the greatest facility, and affords ammoniac by its putrefaction,'though it does not itself contain that sub- Vol. II. 3 E 402 ANALYSIS OF URINE. Stance. At the same time a substance is precipitated of an earthy appearance, but which in reality is a true phos- phate of urine. It is this same salt which form^ the sediment of urine, which is observed by exposing it to cold dur- ing the winter, even though the urine be of a person in perfect health. When urine has, by a sufficient evapora- tion, acquired the consistence of syrup, it need only be exposed, in a cool place, to obtain crystals, in which ana- lysis has proved the existence of the phosphates of soda and of ammoniac. This precipitate of crystals has been distinguished by the name of fusible salt, native salt, mi- crocosmic salt. Urine may be deprived of all saline mat* ter by repeated solutions, filtrations, and evaporations; the matter which adheres to these crystals, and of which they may be cleared by these operations, is soluble, partly in alcohol, and partly in water. The saponaceous sub- •■ stance, or that which is soluble in alcohol, is capable of crystallization, dries difficultly, and affords by distillation a small quantity of oil, of carbonate of ammoniac^ of mu- riate of ammoniac, and the residue converts syrup of vi- olets to a green. The extractive principle is easily dried, and exhibits the same phenomena in distillation as animal substances. See Rouelle. The phenomena exhibited by the spontaneous elecom- position of urine, are very interesting to be knotvn ; on which subject an excellent memoir of Mr. Halle in the volume of the Society of Medicine for 1779, may be con- sulted. Urine left to itself soon loses its smell, which is succeeded by a smell of ammoniac, which is likewise dis- sipated in its turn. The colour becomes brownish, and the smell fetid and nauseous. We are indebted to Mr. Rouelle for a valuable observation—that crude urine uri- na potus, presents Arery different phenomena; and that it becomes covered Avith mouldiness,like the expressed juices of vegetables. Putrefied urine has much less acid in the disengaged state than Avhen it is fresh. The fixed alkalis and lime disengage much ammoniac from urine by decomposing the phosphate of ammoniac. The acids destroy the smell of urine by combining Avith the ammoniac, AA'hich is die principal vehicle of that sniell. We may therefore consider urine, in its natural state, as AA'ater holding in solution matters purely extractive, and phosphoric or muriatic salts. These phosphoric salts have : PHOSPHATE OF AMMONIAC AND SGDA: 403 hme, ammoniac, or soda, for their basis : Ave shall take J a slight view of each in particular. That which is called fusible salt, is nothing but a mix- ture of all die salts contained in urine, clogged Avitii the i extractive principle. All the ancient chemists advised 1 evaporation and repeated filtration, to clear them from this animal extract; but Messrs. Rouelle and the Duke de Chaulnes have observed, that great part of the salt is dis- engaged and dissipated by these operations to such a de- gree, that three-fourths are lost. To avoid most of this loss, the Duke de Chaulnes advises solution, nitration and cooling in well-closed vessels. Two strata of salt are then obtained; the upper of Avhich appears to have the form of square tables, Avherein Rouelle observed tetrahe- dral prisms flattened with dihedral summits. This is the phosphate of soda : and beneath this lies another salt cry- stallized in regular tetrahedral prisms, and is the phosphate of ammoniac. 1. The phosphate of ammoniac usually-exhibits the form of a very compressed tetrahedral rhomboidal prism *. but this form varies much; and the mixtures of the phos- phate or muriate of soda cause an infinity of modifica- 't tions in it. The taste of this salt is cool, afterwards urinous, bitter and pungent. This salt swells up upon die coals, emits a strong smell i of ammoniac, and melts by the blow-pipe into a very fixed and very fusible glass. It is soluble in Avater. Five parts of cold Avater, at ten degrees of Reaumur, dissolved only one of this salt; but at the temperature of sixty degrees this salt is decom- posed, and a portion of its acid is volatilized. It serves as a flux to all the earths; but in this case its alkali is disengaged, and the phosphoric acid unites with the earth, as I find by experiment. Bergmann proposed it as a flux. The fixed alkalis and lime-water disengage the ammoniac. When this salt is heated Avith charcoal, it affords phos phorus. 2. The phosphate of soda \vas made known in 1740 'l by Haupt, under the name of sal admirabile perlatum. Heilot before him, anel Pott seventeen years after him: 404 PHOSPHATE OF SOL1 A. took it for sclcnite. Margin If gave an accurate descrip- tion of it in his Memoir.-, in 1745; and Rouelle the younger described it at full length in 1770, under the name of fusible salt with base of natruni. All agree that it eliffers from the preceding in not affording phospho- rus with charcoal. According to Roucile, its crystals are flattened irregu- lar tetrahedral prisms, AA'ith dihedral summits. The four sides of die prism are two irregular alternate pentagons, and two long rhombi truncated slopeAvise. When exposed to heat it fuses, and affords a glass Avhich becomes opaque by cooling. It is soluble in distilled Avater, and the solution turns syrup of violets green. It does not afforel phosphorus AA'ith charcoal. Lime disengages the soda. It may even be obtained in a caustic state, if the precipitation be effected by lime-water. The mineral acids, or eA-en distilled vinegar, elecom- posc it by seizing its alkali. Mr. Proust, to whom avc are indebted for all the accurate information Ave possess concerning these substances, AA'as of opinion, that the base to Avhich the soda adhered Avas not the phosphoric acid, but a very singular salt, Avhose properties greatly resembled those of the aciel of borax. He found this salt in the mother Avater, after having decomposed the phos- phate of soda by the acetous acid, anel obtained the ace- tite of soda by crystallization. He obtained this same salt by dissolving and evaporating the rcsielue of the dis- tillation of phosphorus. One ounce of phosphoric glass contains five or six drams. This salt was characterized by the folloAving properties : 1. It crystallizes in parallelograms. 2. Its taste is alkaline, and it turns syrup of violets green. 3. It swells up in the fire, reddens, and melts. 4. It effloresces in the air. This may not take place when the phosphoric aciel has not been sufficiently decom- posed by the distillation to leave the aikali disengaged, as I have observed. 5. Boiling Avater dissolves six grc^s per ounce. C. It assists the vitrification of earths, and forms a per- fect glass with siiex. PHOSPHATE OF SODA. 405 7. It decomposes nitre and marine salt, and separates their acids. 8. It is insoluble in alcohol. Mr. Klaproth has published in Crell's Journal an ana- lysis of the fusible salt, in which he has shewn that the pearly salt, or salt of Proust, is merely the phosphate of soda. To prove this nothing more need to be done than to dissolve this salt in Avater, and to aciel a solution of nitrate of lime. The nitric acid seizes the soda, and the phos- phoric acid is precipitated Avith the lime. The phospho- ric acid may afterwards be separated by means of the sul- phuric acid. If the phosphoric acid obtained by the sIoav com- bustion of phosphorus be saturated Avith soda slightly in excess, the fusible salt is formed; if this excess be taken up by vinegar, or if more phosphoric aciel be added, the substance describee! by Proust is form- ed. The phosphate of soda is not decomposable by char- coal ; anel it is at present clearly seen Avhy the fusible salt affords but little phosphorus; and why Kunckel, Margraff and others recommended a mixture of the mu- riate of lead : for by this means the phosphate of leael Wcis formed, which permits the decomposition of the phosphoric acid, and affords phosphorus.* * The most economical mode of preparing the phosphate of soda, is the following. Take three parts of bones calcined to whiteness, powdered and sifted, mix them with water to a thin consistence, and add one part of the sulphuric acid, stirring them well together. An efferves- cence will take place, owing to the carbonic acid disengaged from the carbonate of lime, contained in the bone ash, and the whole presently becomes very thick. Add more water till it is again reduced to a very thin liquid, and either leave the materials together for two or three days, frequently stirring them, or the operation may be shortened by heating the mixture four or five hours. Then filter through linen, wash the insoluble part with hot water repeatedly, and add all the wash- ings to the first filtered liquor. Saturate this liquor with carbonate of soda added to excess, whereby some phosphate of lime is precipitated; boil and filter again, and then evaporate ihe clear solution consider- ably but not to a pellicle : by cooling, fine crystals of phosphate of soda will form. '1 he mother water is then to be examined ; if acid, more carbonate of soda must be added, if a little alkaline, the evapo- ration must simply be continued, but if too much so, some of the ori- K)6 CALCULUS OF THE HLADDEIi. Concerning the Calculus of the Bladder. Paracelsus made some researches concerning the calcu- lus of the bladder, Avhich he calls duelech. He consi- ders it as a substance intermediate betAveen tartar and stone, and thinks that its formation is owing to the modi- fication of an animal resin: he supposes it to be absolute- ly similar to the matter of the gout. Vanhelmont does not admit of this analog)'; and con- siders the calculus as an animal coagulum produced by the salts of urine, and a volatile earthy spirit. Boyle found this calculus to be composed of oil and volatile salt. Boerhaave supposed it to consist of a subtle earth, inti- mately united with alkaline volatile salts. Hales has ob- served that a calculus of the weight of tAvo hundred and thirt) grains afforded six hundred and forty-five times its volume of air, and that there remained only a calx of the Aveight of forty-nine grains. Independent of this chemical information, some physi- cians, such as Alston, De Haen, Vogel, Meckel, &c had observed the solvent poAver of soap, lime-water, and alkalis. But we possessed no accurate ideas on this subject until it Avas seriously taken up by Scheele and Bergmann. The bezoar of the bladder is formed for the most part of a peculiar concrete acid, which M. De Morveau calls the Lithiasic Acid. (The Encyclopedic Methodique may may be consulted, from Avhich the present article is an ex- tract.) ,,inal acid liquor is to be added, (and therefore a small portion should be reserved in the first instance, before the carbonate of soda is add- ed, and by further evaporation and crystallization, an additional por- tion of phosphate of soda may be procured whilst any of the mother liquor remains. From 2100 parts of calcined bones treated by 700 parts of sulphuric acid, 667 parts of carbonate of soda will be required for complete sa- turation, and from these materials 855 parts of phosphate of soda will be procured.*—Am. Ed. * Annates de Chiraie. torn, xxxix, p. 269. CALCULUS OF THE BLADDER 407 The calculus is partjly soluble in boiling Avater. The lixivium reddens the tincture of turnsol; and by cooiing deposites most of what it had dissolved. The crystals thus separated are the concrete lithiasic acid. Scheele has likewise observed—1. That the sulphuric docs not dissolve the calculus unless assisted by heat, and that it is then converted into the state of sulphureous acid. 2. That the muriatic acid has no action upon it. 3. That the nitric acid dissolves it Avith effervescence, and disengages nitrous gas and carbonic acid. This solution is red; it contains a disengaged acid, and tinges the skin of a red colour. This solution is not precipitated by the muriate of barytes, nor rendered turbid by the oxalic acid. 4. That the calculus Avas not attacked by the carbonate of potash; but that the caustic alkali dissolved it, as well as the volatile.alkali. 5. That one thous-.md grains of lime-water dissolved 5,37 by mere digestion, and that it Avas again precipitated by acids, 6. That all urine, even that of infants, held a small quantity of the matter of cal- culus in solution; which may perhaps be the cause that when this matter finds a nucleus in the bladder, it more easily encrusts it. I have seen a calculus Avith a large plum stone in its centre. 7. That the brick-coloured deposition from the urine in fevers, is of the nature of the calculi. These experiments exhibit several important consequen- ces with regard to the composition of die calculus, and the properties of the lithic acid. The calculus contains a small quantity of ammoniac. The coaly residue of the cumbustion indicates animal substance of the nature of jelly. The celebrated Scheele did not find it to contain a particle of calcareous earth; but Bergmann precipitated a true sulphate of lime, by pouring the sulphuric acid into the nitrous solution of the calculus. He admits that the lime is very small in quan- tity, as it rarely exceeds the two-hundredth part of the en- tire Aveight. The same chemist lias detected a AA'hite spongy substance, not soluble in water, nor attacked bA' spirit of Avine, or acids, or alkalis; Avhich at last affords a coal of difficult incineration, and which the nitric acid does not dissolve, even in the state of ashes; but this 1»J8 All TH R I TIC COXCHETIO \ S. matter exists in so small a quantity, tint he could not procure enough to examine it. The calculus is not therefore analogous to bones in its nature; neither is it a phosphate of lime, as has been pretended.' These are the results of the chemists of the north ; but I must observe that, after having decomposed many calculi by the caustic alkali, I have precipitated lime anel formed phos- phates of potash. Some j--h\>:<.:aiis, such as Sydenham, Chcyne, Murray, ccc. have i).might that the arthritic concretions were of the same nature as the calculus. The use of which Boerhaave made of alkalis in the gout; the virtues aelmliicel by Fred. Hoffmann in the thermal Avaters of Carlsbad, which contain soda,, with an excess of car- bonic aciel; the authority of Springsfeld, Avho asserts that the calculus is \ cry speedily dissolved in these waters, even in the urine of those who drink them; the success of lime-water, used by Alston in the gout—all conspire to'give some credit to the opinion of these early physici- ans. But the following experiments do not agree Avith this notion. VansA\*icicn affirms that the arthritic concretion never ac- quires the harshness of the calculus. Pinelli (Phiios. Trans.) distilled in a retort three ounces of the arthritic matter collected from the articulations of several gouty persons; anel he obtained ammoniac, AA'ith some drops of oil, the residue weighing tAvo gross. This residue, which was soluble in the muriatic, sulphuric, anel acetous acids, Avas not attackcei by volatile alkali. An observation of .VIr. Rcering Avas published in the Memoirs of the Aca- demy of S.ockholm for 1783, Avhich ascertains that the concretions expectorated by an old man subject to the gout, Avere found to be of the nature of bone, or phos- phate of lime. But one of the neAvest and most import- ant fact:; is that of Watson, in the Medical Communicati- ons of London, vol. i. 1734. lie concludes, from the examination ci the arthritic concretions of a gouty body, that this substance is very different from the matter of the calculus, since it is soluble in the synovia, and easiiv mixes w'uh oil and water, which the calcuhis el >es not. DISCOVERY OF PHOSPHORUS. 409 It follows from our Observations on the lithic acid, that this acid is concrete, and sparingly soluble in water; that it is decomposed, and partly sublimed by distilla- tion. This acid decomposes the nitric acid, unites with earths, alkalis, and metallic oxides. It yields its bases to the Aveakest vegetable acids, not excepting the car- bonic. , CHAPTER I. Concerning Phosphorus. PHOSPHORUS is one of the most astonishing pro- ducts of chemistry. It is pretended that traces of the knowledge of this substance exist in the AATitings of [ the earliest chemists : but the most positive information AA'e possess on this subject is found in the history given by f Leibnitz, in the Melanges de Berlin for 1710. He gives die discovery to Brandt, a chemist of Hamburg, who during a course of experiments upon urine, with a view of extracting a fluid proper to convert silver into gold, discovered phosphorus in the year 1667. He communi- cated his discovery to Kraft, who shevAed it to Leibnitz; land being afterwarels in England, he communicated it to Boyle.* Leibnitz caused the first inventor to be intro- duced to die Duke of Hanover, before whom he perform- ed the Avhole operation; and a specimen of the phospho- rus Avas sent to Huygens, Avho sheAved it to the Academy of Sciences at Paris. * As Boyle communicated the process for making phosphorus to the Royal Society as a discovery of his o\vn> and it is entered as such : in the Philosophical Transactions, I cannot avoid animadverting, on this impeachment of his integrity, which is copied from one chemi- ■'' cal book into another. It is grounded on no better foundation than the assertion of Kraft, a dealer in secrets, Avho, after having deceived Vol. II. 3F 410 PROCESSES TOR MAKING l'HOSl'HOK U J. It is said that Kunckel had associated himself will; Kraft to purchase the process from Brandt. Bui Kunckel haA'ing been dcceiAed by Kraft, who kept the secret to himself, knowing that urine Avas made use of, set to Avork, and discovered a process for making the substance ; and it is this Avhich led chemists to call it by the name of Kuncl.el's Phosphorus. Though the process Avas rendered public, Kunckel, and a German called Godefrcd Hatwithf, Avere the only per- sons Avho prepared phosphorus for a long time. It Avas not till the year 1737, that it was made in the laboratory of the Royal Garden at Paris. A foreigner executed thin operation in the presence of Messrs. Hellot, Dn Fay, Geoftroi, anel Du Hamel. An account of the opcratiou may be seen in the volume of the Acaelcmy for 1737. Hellot has collected all the essential circumstances. Mar- graff, in the year 1743, published a iicav and more easy method, Avhich has been followed until Scheele andGahn taught us to obtain it from bones. The process of Margraff consists in mixing the muri- ate of lead, Avhich remains after the distillation of four pounds of minium and tAvo of sal ammoniac, with ten pounds of the extract of urine of the consistence of ho- ney. Half a pound of charcoal in poAvder is added ; the mixture is drieel in an iron pot until it is reduceel to a black powelcr. This powder is to be put into a retort; and tii2 volatile alkali, the fetid oil, and the sal ammoniac, distilled off. The residue contains the phosphorus. It is assayeei by throwing a small quantit)- on hot coals : if it hit friend Kunckel, associated with him for the purchase of this se- fct. 1 might insist, in defence of the candour and otherwise un- impsached integrity of lioyle, that his assertion ought infinitely to outweigh that of the other. Not to insist, however, upon this, it may lie noticed that this new and famous product was known :o have been extracted from urine; that Kunckel is universally admitted as the discoverer, from his having formed it upon no fuller informa- tion than this ; that Boyle might with equal probability he admitted to have discovered it in the same manner, and upon information equally slight; and that the probability of this is rendered incom- parably greater, by the consideration that none of these chemists snade any complicated experiments, but merely applied ^he force of Tire to urine until this product at last came over. T. t Spelled Hanckwitz by most authors. He was in<:t: ucted by PROCESSES FOR MAKING PHOSPHORUS 411 emits a smell of garlic, and a phosphoric flame, it is to be put into a good earthen retort, and elistilieel. Much more phosphorus is obtained by this than by the old pro- cess ; and this depenels on the addition of the muriate of lead by Margraff, Avhich decomposes the phosphate of so- da, forming a phosphate of lead, which affords phospho- rus ; Avhereas the phosphate of soela is not decomposable by charcoal. The famous chemist of Berlin has likewise proved that it Avas the fusible salt of urine Avhich affords the phosphorus. Mr. Galin published, in die year 1769, that the earth of calcined bones consisted of lime uniteel Avith the acid of urine'; but Scheele was the first to prove that by de- composing this salt of bones by the nitric and sulphuric acids, evaporating the residue in which the phosphoric acid exists in a disengaged state, and distilling die extract with powder of charcoal, phosphorus is obtained. These circumstances, related by Eergmann himself in his notes to the Chemistry of Schefter, attribute to Scheele the dis- covery of extracting phosphorus from bones. It Avas not until the year 1775 that the process Avas publisheel in die Gazette Salutaire de Bouillon. Additions and improve- ments have been successively made in this process, of which accounts may be seen in the Dictionnaire Encyclo- pedique. The process which lias most constantly succeeded AA'ith me, is the following : The hardest bones are selected and burned. By this combustion the external part becomes white, while the in- ternal part is blackish. These burned bones must then be pulverized, and put into a turine, or in a round hooped wooelen vessel. Half their Aveight of oil of vitriol is then to be poured on, and constantly stirred. During the agitation a considerable heat is excited. The mixture must be left in digestion for tAvo or three days; after which, water must be gradu- ally aelded, and stirred. I digest this last mixture upon the fire, in order to encrease the sohent power of the Avater. . , , , • The water of the lixivium is then to be evaporated in vessels of stone ware, silver or copper. Mr. Pelletier re- commends this last mettd; because, according to hinj. 412 PHOSPHORIC CLASS. die phosphoric acid does not attack copper. The evapo- ration must be carried to dryness; more boiling Avater must be poured on the residue ; and this washing must be continued until the matter be exhausted, which may be knoAvn by the Avater being no longer tinged yellow. All these Avaters are to be evaporated, and afford an extract. To separate the sulphate of lime, the extract must be dis- solved in the least possible quantity of Avater, then filtered, andthesalt remains on the filtre. This extract may be mixed Avith poAvder of charcoal, and distilled : but I prefer con- verting it into animal glass; for which purpose I put the extract into a large crucible, and urge the fire. It SAvells up at first, but at last settles; and at that instant the glass is made. This glass is white, of a milky colour. Be- cher Avas perfecdy acquainted Avith it: but concealed his process, on account of the abuses which, according to him, might lie made of it—propter varios abusus. He tells us, in proper terms, homo vitrum est, et in vitrum redigi potest, sicut et omnia animalia. He regrets that the Scythians, avIio drank out of disgusting sculls, were not acquainted with the art of converting them into glass. He sheAvs that it Avould be possible to form a series of one's ancestors in glass, in the same manner as Ave pos- sess them in painting, &c. I observed once, to my great astonishment, that the phosphoric glass I had just made, emitted veiy strong electric sparks : these flew to the hand at the distance of two inches. I exhibited this phenomenon to my audience of pupils. This glass lost the property in two or three days, though preserved in a capsule of common glass. It sometimes happens that this glass is deliquescent, but it is then acid ; and this circumstance arises from too large a quantity of sulphuric acid, or from this acid not having been saturated by a digestion of sufficient continu- ance. I have likeAvise obtained glass of the colour of tur- quoise, A\rhen I performed the evaporation in copper ves- sds. This glass may be deprived of the bubbles it usually contains, by keeping it for a time in a violent heat; it is then transparent, and may be cut like a diamond. Ac- cording to Crell, its specific gravity is to that of Avater as DISTILLATION, &C. OF PHOSPHORUS. 41o three to one, Avhile diat of diamond is as three and a half to one. This glass is insoluble in Avater, &c. A ske- leton of nineteen pounds, burned, affords five pounds of phosphoric glass. I pulverize this glass, mix it with equal parts of poAv- der of charcoal, put it into a porcelain retort well coated, the beak of Avhich I partly plunge into the Avater of the receiver, so that nothing can escape but air or phosphoric gas. I adapt a large tube to the tubulure of the receiver, and plunge it into a vessel filled Avith water. The fire be- ing raised by degrees, the phosphorus comes over the moment the mixture is ignited. The phosphorus sublimes, partly in the form of a fume which congeals; and is pre- cipitated upon the surface of the water, partly in the form of inflammable gas, and partly resembling melted Avax, which drops in beautiful transparent tears from the neck of the retort. The theory of this operation is easily ex- plained. The phosphoric acid is displaced by the sulphu- ric acid, as is shewn by the large quantity of sulphate of lime which* is obtained. All the other operations tend only to concenttate this phosphoric acid, Avhich is still combined Avith other animal substances, and the distilla- tion with charcoal decomposes the phosphoric acid; its oxigene unites Avith the coal, and affords a carbonic acid, while the phosphorus itself becomes disengaged. To purify the phosphorus, a piece of chamois leather is moistened, and the mass of phosphorus is put into it. This being immersed in a vessel of boiling water, the phosphorus melts, and is passed through the skin like- mercury. The skin cannot be used more than once;. the phosphorus, which might be passed a second time, would become coloured. This process Avas contrived by Mr. Pelletier. In order to form phosphorus into sticks, a funnel with a long neck may be used, the lower orifice being closed with a small cork, or piece of soft wood. The funnel is then to be filled with water, the phosphorus put in it; and this being plunged in boiling Avater, the heat is com- municated to that of the funnel; anel melts the phospho- rus, which runs into the neck, and takes that form. The funnel is then removed into a vessel of cold Avater; and when the phosphorus is perfectly cooled, the cork is taken 414 PROPERTIES OF PHOSPHORUS. out, and the phosphorus thrust out of its mould a\ idi a small piece of Avood. Phosphorus is kept under Avater. After a certain time it loses its transparency, becomes covered Avith a Avhite poAvder, and the A\'ater is acidulated.* In Avhatever manner phosphorus may be made, it is ahvays one and the same substance, characterized by the folioAving properties :—It is of a flesh colour, and evidently transpa- rent. It has the consistence of Avax; and may be cut in pieces with a knife, or tAvisteel asunder Avith the fingers; in Avhich last case the precaution must be taken of fre- quently plunging it into Avater, to prevent its taking fire. When phosphorus is placed in contact Avith the air, it emits a Avhite fume. It is luminous in the dark : and a solid stick of phosphoric may be used to write AA'ith, like a crayon. The marks are visible in the dark; and by ihis means has often been usetl to create fear and Astonish- ment in the minds of the ignorant. When phosphorus is exposed to twenty-four^ degrees of heat, it takes fire AA'ith clecrenitation, burns With a very bright flame, and emits a very abundant white fume which is luminous in the dark. The residue of the combustion is a red caustic substance, which attracts the humidity of (he air, anel becomes resolved into a liquor. This is tht pho:-.phone aciel, Avhich we shall proceed to treat of. Mr. Wilson affirms that the solar rays set fire to phos- phorus ; and proves that this flame has the colour proper to the phosphorus, and not that of the ray itself.—Letter of Mr. Wilson to Mr. Euler, read at the Royal Society of London in June 1779. * This slow acidification of the phosphorus seems to be reversed by the sun's light. Sticks of phosphorus, which had become co- vered with a white powder, were exposed under water to the sun's light, which converted them to an orange yellow colour in such parts as were acted upon by the direct light. This fact appears to be of the same nature as the colouring of the nitric acid, and othci similar phenomena. T. •f Twenty-four degrees of Reaumur answer to eighty^ix of Fah- renheit. The vivid combustion of phosphorus takes ^laxe at differ- ent temperatures* accord;ng to its purity; but the present is very low. By taking phosphorus into a freezing atmosphere, its faint flame disappears, Jmd it seems to require a temperature of sixty det-rees to revive it. I found the vivid combustion to take place a' one hundred and sixty degrees. T. PHOSPHORIC BOUGIES. 415 An advantageous use has lately been made of the com- bustible property of phosphorus, to procure fire conve- niently, and in all situations, by means of phosphoric ta- pers or matches, and the philosophical bottles, the method of making Avhich we shall point out. 1. The most simple process for making the phospho- ric matches, consists in taking a glass tube, four inches long, and one line in diameter, closed at one end. A small quantity of phosphorus is introduced into the tube, and pushed to its further end ; after Avhich a taper covered with a small quantity of Avax is introduced into the same tube. The open end is then hermetically sealed, and the other end is plunged into boiling water. The phosphorus melts, and fixes itself upon the match. A line is draAvn at one third of the length of the tube, with a flint, that it may be broken as occasion may require. The match is to be draAvn out quickly, to inflame the phosphorus. The process of Mr. LeAvis Peyla, to make the inflam- mable bougies, consists in taking a glass tube, five inches long and tAvo lines Avide, One end of which is sealed with the blow-pipe. Small tapers of wax are prepared Avith three double threads of cotton twisted together. The ex- tremity of the match or taper is half an inch long, and must not be covered Avith wax. A piece of lead is laid in a saucer filled with water; and upon this the phosphorus is cut, beneath the water, into fragments of the size of a grain of millet. One of these grains is to be dried, and introduced into the tube of glass ; after Avhich the fortieth part of a grain of very elry sulphur is to be added, that is to say, half the weigtit of the phosphorus. One of the bougies is then taken, and its extremity dipped in very clear oil of wax. If too large a quantity rises, it must be dried with a cloth. ! The match is introduced into the tube with a turnine or twisting motion between the fingers. The bottom of the tube must then be plunged in boil- ing water, to soften the phosphorus; observing to keep it no longer than three or four seconds in the water. The other exu*emity of the tube is aftenvards sealed. These bougies must be kept in a tin tube, to avoid the danger of inflammation. -116 HABITUDES OF PHOSPHORUS. 2. To form the phosphoric bottles, a glass bottle is heated by fixing it in a laelle full of sand, anti two or three small pieces of phosphorus are then introduced into it A small red hot iron wire is used to stir the phosphonis about, and cause it to adhere to the internal surikce of the bottle, Avhere it forms a reddish coating. The heated Avire is introduced repeatedly ; and AA'hen all the phospho- rus is thus distributed Avithin the botde, it is left open for a quarter of an hour, and afterwards corked. When this is used, a common match tipped with sulphur is intro- duced into the botde, turned round, and quickly drawn out. The phosphorus Avhich sticks to the sulphur takes fire, and lights die match. The theory of this phenomenon depends on the circum- stance that the phosphorus is strongly dried, or half cal- cined, and needs only the contact of air to set it on fire. Phosphorus is soluble in oils, more especially ithe vola- tile oils, which then become luminous. If this solution be kept in a bottle, a phosphoric flash, which emits a small quantity of light, will be seen every time the bottle is opened. The oil of cloves is used in this operation. The combination of phosphorus and oil appears to exist naturally in the gloAv-Avorm, kimpyris spieneiidula Linnaei. Forster of Gottingen observes, that the shining matter of the gloAv-worm is liquid. If the glow-worm be crushed between the fingers, the phosphorescence remains on the finger. Henckel reports, in the eighth dissertation of his Pyritologia, that one of his friends, of a sanguine tem- perament, after having danced much, perspired to such a degree that he thought his life in danger. While he un- dressed, traces of phosphoric flame were seen on his shirt, which left yellow red spots behind them, resembling the residue of burned phosphorus : this light was long visible. A phosphoric gas may be extracted from phosphorus, which takes fire by the mere contact of the air. Mr. Gengembre has shewn the methexl of extracting it, bv digesting alkalis upon it (Memoir read to the Acade- mv at Paris the 3d of May 1783); and at the same time I sheAvcd that it might be extracted by means of acids, which are decomposed upon phosphorus, I fadve like- wise taken notice, in my Memoir upon the decomposi- tion of the nitric acid by phosphonis, that Avhen die acid PHOSPHORUS, WHERE POUND. 417 is digested upon it, a gas escapes, which takes fire in the receiver, and has several times afforded me the appearance of flashes of lightning striking through the cavity of the vessels. But this phenomenon disappeared as soon as the vital air was absorbed. . It is to the disengagement of a gas of this nature that we may attribute the ignes fatui which play about bury- ing grounds, anel generally in all places where animals are buried and putrefy. It is to a similar gas that we may refer the inflammable air Avhich constantly bums in certain places, and upon the surface of certain cold springs.' Phosphorus is found in the three kingdoms. Mr. Gahn found the phosphoric acid in lead. Siderite is a phos- phorus of iron. The seeds of rocket, of mustard, of garden cresses, and of wheat, treated by Margraaff, af- forded him a fine phosphorus. Mr. Meyer of Stetin has announced, in the Chemical Annals of Crell for the year 1784, that the green resinous part of the leaves of plants contains the phosphoric acid. Mr.' Pilatre du Rozier re- newed the opinion of Rouelle in 1780 (Journal de Phy- sique for November), who considered the phosphoric acid as analogous to that of mucilaginous bodies ; and he af- firms that the distillation of pyrophorus affords five or six grains of phosphorus in the ounce. The phosphoric acid exists in urine, bones, horns, &c. M. Maret, by treating twelve ounces of beef by combustion, obtained three gross of transparent phosphoric glass. M. Crell obtained it from beef suet and human fat; M. HankAA'itz from ex- crements ; Leidenfrost from old cheese; Fontana from fishes' bones; Bemiard from egg shells, &c. Messrs. Macquer and M. Struve found the phosphoric acid in the gastric juice. The most interesting combination of phosphorus is that . which it forms Avith vital air. This is always the phos- phoric acid; but the acid appears to be modified by the manner in which it is made. Phosphorus unites Avith oxigene—1. By deflagration, ', or the rapiel combustion. 2. By the slow combustion. 3. In the humid way, more especially by the decomposi- tion of the nitric acid. Vor.. II. 3G 418 BECOMP0SITI0N OF PHOSPHORUS. 1. If phosphorus be exposed to a dry heat of twenty. four degrees, it takes fire, emits a white dense fume, and leave a reddish residue, Avhich powerfully attracts die humidity of the air and becomes resolved into a liquor. This combustion may be performed under glass A-essels; in Avhich case Avhite flocks are deposited on the sides of die glass, Avhich resolve into a liquor by the contact of moist air, and form the phosphoric acid. Care is taken to introduce an additional quantity of vital air Avhen the combustion of the phosphorus has not been completed. M. Lavoisier has burned phosphorus, by the assistance of a burning glass, under a glass vessel plunged in mer- cury (Memoirs of the Royal Academy of Sciences, 1777.) Margraaf had observed that air is absorbed in this operation. M. Morveau, in die year 1772, hadj .declared the same from his OAvn experiments; anel Fontana proved that phosphorus absorbs anel vitiates air, like every other combustible substance. Messrs. Lavoisier and De la Place found diat forty-five grains of phosphorus absorbed 65,62 of vital air. The acid obtained by this means is impure. It al- Avays contains phosphorus in solution, not saturated with oxigene. 2. Phosphorus is most completely decomposed by the sIoav combustion. For this purpose the neck of a glass funnel is inserted into a bottle, and sticks of phosphorus are disposed round in the funnel, so as not to touch each other; a small piece of glass tube being put into the neck, to prevent their falling through. A paper is tied over the funneL The phosphonis is slowly decomposed; and, as it becomes converted into a fluid, it flows into the bottle, Avhere it forms a liquid Avithout smell or colour. This acid almost ahvays retains a small quantity of unde- composed phosphorus, from AA'hich it may be cleared by digesting alcohol upon it, Avhich dissolves the phosphorus, without A'olatilizing the acid. Oc.e ounce of phosphorus produces in tiiis manner three ounces of phosphoric acid. PROPERTIES OF PHOSPHORIC ACIU. 419 3. The nitric acid may be decomposed by digestion upon phosphonis. The nitrous gas is dissipitated; and the oxigene remains united to the phosphorus, with which it forms phosphoric acid. When the nitric acid is very concentrated, the phosphorus takes fire, and bums at its surface. I published this process, with all the circum- stances of the operation, in 1780, the same year in which the excellent Memoir of M. Lavoisier on the same question: was printed, and of which I had then no know- ledge. The water in which phosphorus is kept, contracts acid- ity in the course of time; which shews that the Avater itself is decomposed, and yields its oxigene to the phos- phorus. Phosphorus precipitates some metallic oxides from their soietions in the metallic state. It is observed that acid is formed in this operation; which proves that the oxigene quits the metal to unite with the phos- phonis. The phosphoric apkl is clear, inodorous, without being corrosive. It may tie concentrated to dryness. Crell hav- ing concentrated it to dryness, found its specific gravity, compared Avith water, to be as 3. 1. This acid is very fixed. If it be concentrated in a matrass, the water is first dissipated, a smell of garlic is soon perceived, which arises from a portion of phosphorus from which this acid is difficultly cleared: and vapours likewise rise. The liquor becomes turbid, assumes a milky appearance, and a pasty consistence; and if the matter be put into a crucible, on hot coals, it boils consi- derably. The vapour which issues renders the flame oTeen; and the mass at last becomes converted into a Avhite transparent glass insoluble in water. The phosphoric acid has no action on quartz. It dissolves clay with ebullition. It dissolves barytes; and unites to clay with singular •facility, Avith which it forms a salt of sparing solubility. The solution Avhen Avell charged, lets fall, at the end of four and twenty hours, crystals in small thin flattened iieeelles, several lines .long, and obliquely tnmcated at each end. The phosphoric acid precipitates lime from lime- -120 PHOSPHORIC SALTS. Avater, and forms a true phosphate of lime, a -cry similar to the basis of bones, and decomposable by the mineral acids like that substance. The phosphoric acid, saturated Avith potash, forms a very soluble salt, Avhich affords tetrahedral crystals termi- nating in tetrahedral pyramids. This phosphate is acid, SAvells up on hot coals, and is difficult of fusion. Lime- water decomposes it. Soda, combined with the phosphoric acid, affords a salt of a taste resembling that of the muriate of soda, This phosphate does not crystallize, but become s convert- ed into a gummy and deliquescent mass by evaporation. M. Sage affirms that phosphate of soda prepared Avith the acid of the sIoav combustion, forms a salt susceptible of crystallization. Dr. George Pearson has combined the phosphoric acid obtained by nitric acid Avith soda, and obtained a neutral salt in rhomboids. This salt, though saturated, turns syrup of violets green, effloresces in the air, and has a saline taste resenu bling that of common salt. It purges in the dose from six to eight drams, Avithout producing eidier nausea or griping, and Iris not a disagreeable taste. The phosphoric acid acts only on a small number of metallic substances. On this subject the Avorks of Messrs. Margraaf and De Morveau may be con- sulted. The phosphoric acid has a very evident action on oils. Mixed Avith an equal portion of olive oil, it acquires a ferwn colour by mere agitation, which subsists even after the separation. This shade increases if the two fluids be digested together; the acid becomes diick; and the oil which floats above becomes black and coaly, and emits a strong smell. ANIMAL SUBSTANCES. 421 CHAPTER X. Concerning certain Substances obtained from Animals for the Use of Medicine and the Arts. THERE is not perhaps any animal product Avhosc virtues have not been celebrated by some of die physicians; and there are few animals which have not at some time or other been mentioned as contributing to the advantage -of medicine. Time however has happily con- demned to oblivion those prexluctions which ought never to have possessed celebrity: and Ave shall accordingly, on the present occasion, attend only to such as experience has shewn to possess the virtues and powers attributed to diem. We shall not therefore treat of the lungs of the fox, the liver of the wolf, the feet of the elk, the jaws of the carp, the nests of the swalloAv, the powder of the toad, the dung of the peacock, the heart of the viper, the fat of the badger, nor even that of the hanged male- factor. Various quadrupeds, cetaceous animals, birds, and fishes, afford products in which chemical and medical ex- perience has ascertained very evident virtues. ARTICLE I. Concerning the Products afforded by Quadrupeds. Under this article we shall treat of the products most in use which are extracted from quadrupeds, These are castoreum, musk, and hartshorn. 422 CASTOREUM. THE MUSK ANIMAL. 1. The name of Castoreum is given to an unctuous fluid contained in two pouches situated in the inguinal re- gion of the male or female castor. An accurate descrip- tion of it may be seen in 'the Encyclopedic. This very odorant substance is soft, and nearly fluid when recently extracted from the animal; but it dries in the course of time. It has an acrid, bitter, and nauseous taste; and its smell is strong, aromatic, and even stinking. Alcohol dissolves a resin which colours it; water ex- tracts an abundant principle. By evaporation of the Ava- ter a salt is obtained, the nature of which is little known. Castoreum affords bv distillation a small quantity of vo- latile oH, ammoniac, &c. The uses of castor in the ceconomy of the animal are unknown. The ancients had the credulity to be- lieve that the creature itself took it when its stomach was weak. It is used in medicine as a powerful antispasmodic, in the dose of a few grains in substance ; and it enters as a component part into boluses, extracts, &c. It is advan- tageoujly joined with opium; and its spirituous tincture is also prescribed in suitable liquids, in a dose from twen- ty-four to thirty-six drops. We see clearly, from the little chemical information wt possess respecting this substance, that it is a resin joined with a mucilage, and a salt which facilitates the union of its principles. 2. The name of Musk is given to a perfume obtained from various animals. In 1726 an animal was received, under the name of the Musk Animal, in the Royal Mena- gerie, which came from Africa, and resembled the civet. Mr. Perrault has left a description of it. It was sup- ported six years upon raw flesh. M. De la Peyronnie gave a very good description of it to the Academy of Sciences for the year 1731s The organ AA'hich contained the musk was situated near the genital parts. It was a female. At the aperture of the bag AA'hich contained the musk the smell Avas so strong, that M. de la Peyronnie could not inspect it without in- eeHivenience. This liquor is prepared by two glands, \\ hich transmit it into the common reservoir through n number of small perforations. * MUSK. HARTSHORN. 423 The other animal which affords musk in the East, is of the class of squirrels. It is very common in Chinese Tartary. It carries the musk in a bag beneath the navel This bag, projecting outwards of the size of a pullet's egg, is formed of a membranous and muscular substance, provided Avith a sphincter. Many glands are observable within, which separate the humour. As soon as die beast is killed, this bladder is cut off and tied up : but its con- tents are adulterated Avith the testicles, the blood, and other offals of the animal; for each creature affords no more than three or four gross. Musk must be chosen soft, unctuous, and odorant; and ought to be consumed to- tally upon hot coals. The musk of Tonquin, which is ^ most esteemed, is contained in bags covered with broAvn hair; but that of Bengal is covered Avith white hair. Musk contains nearly the same principles as castore- um. The smell of pure and unmixed musk is too strong and oppressive. It is rendered mild by mixture Avith other substances. It is little used in medicine; is a pow- erful antifepasmodic in some cases; but ought to be admi- nistered with caution, because it often excites nervous af- fections instead of calming them. The smell of musk predominates in certain animals. M. De la Peyronnie knew a man from whose left arm-pit there Avas emitted so strong a smell of musk during the summer, that he was obliged to weaken it to avoid incon, venience. 3. Hartshorn affords several products which are much employed in medicine. The preference is given to this horn because it contains less earthy salt than bones; but all kinds erf" horn may be used indiscriminately. Hartshorn was formerly calcined with the greatest care', and used as a remedy against alvine fluxes. The products of hartshorn which are mostly used at pre- sent, are those obtained by distillation. An alkaline phlegm is first obtained, which is called the Volatile Spirit of Hartshorn. Next conies over a reddish oil, more or less empyreumatic ; and a very great quantity of carbonate of ammoniac, soiled and coloured by the empyreumatic oil. ' The oil which colours the salt may be disengaged by means of spirit of wine, which dissolves it. The coaly jesidue contains natrum, sulphate, and phosphate of lime', 424 ANIMAL OIL OF DIPFEL. SPERMACETI. from which* phosphorus may be obtained by the processes already described. The spirit and the salt obtained from hartshorn are used in medicine as good antispasmodics. The oil duly rectified forms the animal oil of Dippel. As the highest virtues have been attributed to this sub- stance, a thousand methods have been attempted to pu- rify it. For a long time it Avas usual to rectify it a great number of times, in order to have it Avhite and fluid. But Messrs. Model and Baume have advised taking only the first portion which comes over, because this is the most attenuated, and the A\hitest. Rouelle advises distillation Avith AA'ater; and as the most volatile part only rises with the heat of boiling water, there is a certainty of having it very fine by this means. For my part, I distil the em- pyreumatic 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 of the vola- tile oils: but it turns syrop of violets green, as Mr. Par- mentier has observed; which proves that it retains a small quantity of volatile alkali. This oil is used in doses of a few drops in nervous affections, epilepsy, &c. It is used externally, by rubbing it on the skin, as a sedative, and to remove obstructions; but the great virtues formerly at tributed to it are not much credited at present. ARTICLE II. Concerning certain Products afforded by Fishes. The oil of fish, and spermaceti, are the most used among die products obtained from fishes. Spermaceti is a concrete oil extracted from the cacho- iot. The name of Spermaceti is very improper. These animals are of a prodigious size, and afford large quanti- ties of this matter. Piomet rekites that in 1688 a Spanish ship took a whale Avhose head afforded twenty-four barrels of brains, and the body ninety-six barrels of. fat This spermaceti is alAvays mixed with a certain quantity of inconcrescible oil, which is carefully remoA ed. I SPERMACETI. PARTS Of THE CUTTLE FISH. 425s Spermaceti burns with a very white flame. It is made into candles at Bayonne and at St. Jean de Lutz. These capdles are of a shining white colour, become yellow in process of time, but not so soon as Avax and the dense oils. If it be distilled on a naked fire, it does not afford an acid phlegm, but rises totally, at the same time that it assumes a reddish tinge. Several repeated distillations deprive it of its natural consistence. The sulphuric acid dissolves it; and this solution is pre- > cipit^ted like the oil of camphor. The nitric and muria- tic acids have no action upon it. Caustic alkali dissolves spermaceti, and forms a soap which gradually acquires solidity. Alcohol dissolves spermaceti by the assistance of heat, but lets it fall as it cools. Ether likewise dissolves it. The fixed and volatile oils dissolve it by the assistance of heat. This substance was formerly much used. It was given! as an emollient, and softening remedy; but at pre- sent, it is almost forsaken, and not without cause; for it is heavy, insipid, and nauseous. The egg, the scales, and die black fluid of the cuttle- fish are still used in medicine. The eggs deterge the kidneys, and excite urine and the courses. The scales and bones of the cuttle-fish are applied to nearly the same uses : they are likeAvise used as an astringent; and enter into dentifirice powders, collyria, &c. The goldsmiths likeAvise use them to make their moulds for casting spoons, forks, toys, &c. because its spongy part easily receives the impression of metals. The black humour of the cut- f tie-fish, which is found in a bag near the coecum, and of Avhtsh Mr. Le Cat has given a description, may be used instead of ink. We read in the Satires of Persius that the Romans used it as an ink ; and Cicero calls it Atra- mentum. It seems that the Chinese use it as the basis of (heir famous ink. " Sepia piscis est qui habet succum nigerrimum, instar atramenti, quern Chinenses cum bro- ■ [ dio orbwe, vel alterius leguminis, inspissant et formant, et in universum orbem transmittunt, sub nomine Atramenti Chinensis." . (Pauli Hermani Cynosura, t. i. p. 17, par. 2). Pliny was of opinion that the black humour of- the Vol. II. 3-H 426 COMPONENT PARTS OF EGGS. cuttle-fish Avas its blood. Rondele t has proved that it is the bile. This is the fluid the cuttle-fish disgorges Avhen in danger : a very small quantity is sufficient to blacken a large quantity of AAater. Calcined oyster shells are likewise used in medicine as an absorbent. The oil extracted from fish is of the greatest use in tW arts. ARTICLE III. Concerning certain Products afforded by Birds. Most of the birds are used at our tables as a delicate food, but few afford any medical products. The eagle stones, to Avhich so much virtue had been attributed for facilitating labours, the plasters of swallows' nests, and Other similar substances, have all fallen into neglect, as the natural consequence of the observation of matter of fact being substituted in the place of credulity and super- stition. The analysis of eggs begins to be known. They consist of four parts : an osseous covering, called the shell; a membrane Avhich covers the constituent parts of the egg; the Avhite; and the yolk, Avhich occupies the centre. The shell, like bones, contains a gelatinous principle, and the phosphate of lime. The white is of die same nature as the serum of blood. It renders syrup of violets green, and contains uncom- bined chalk; heat coagulates it; by distillation it affords a phlegm Avhich easily putrefies; it becomes dry like horn; and carbonate of ammoniac, and empyreumatic oil, come over. A coal remains in the retort, which affords soda, and phosphate of lime. M. Deyeux has also obtained sulphur by sublimation. Acids and alcohol coagulate it. If it be exposed to the air in thin leaves, it dries, and becomes consistent; and it is on this property that the custom is founded of passing the white of egg over the surface of paintings, to give them that brightness av hich h produced by varnish, and also to defend them from the tfOLK OF EGG. CAN1HARIDES. 427 air. . The drying may be hastened by quicklime; and this mixture affords a lute of the greatest tenacity. The yolk of egg likewise contains a lymphatic sub- stance, mixed Avith a certain quantity of mild oil, which on account of this mixture is soluble in Avater. It is this animal emulsion which is known in France by the name of lait de poulle. Yolk of egg exposed to the fire as- sumes a consistence less hard than the Avhite. If it be bruised, it appears to have scarcely any consistence ; and if it be subjected to the press, it gives out the oil it con- tains. This oil is very emollient, and is used externally as a liniment. There is the greatest analogy betAveen the eggs of animals and the seeds of vegetables; since both contain an oil rendered soluble in water by the admixture of a glutinous substance. The yolk of egg renders oils and resins soluble; and this substance is accordingly much used for that purpose. Calcined egg-shells is an absorbent. White of egg is successfully used to clarify vegetable juices, Avhey, liquors, &c. It coagulates by heat; and then rises to the surface of these fluids, carrying Avith it all the impurities they contain. ARTICLE IV. Concerning certain Products afforded by Insects. Millepedes, cantiiarides, kermes, cochenille, and lac, are the only substances avc shall here treat of, because these are not only the most useel, but are likeAvise the best knoAvn among the products of insects. I. Cantiiarides.—The cantiiarides are small insects witii greenish wings. They are very common in hot countries; anel are found on the Iciacs of the ash, the rose-tree, the poplar, the Avalnut-tree, the privet, &c. Cantiiarides in poAvder, applied to die epidermis, cause blisters, excite heat in the urine, smuigury, thirst, and fever. The) produce the same effect taken internally in a small dose. We read in Pare that a courtezan having presented a ragout poAvdered with cantiiarides to a young man who supped with her, this unfortunate person was 428 ANALYSIS OF C AN TH AR1HES. W0O13-LICE. attacked Avith a priapism, and loss of blood by the anus, of Avhich he diqd. Boyle affirms that pains' at'the neck of die bladder have been produced by the handling of cantharides. We are indebted to Mr. Thouvenel for some informa- tion respecting the constituent principles of these insects. Water extracts a very abundant principle, AA'hich colours it of a reddish yellow, and also a yellowish oily principle. Ether takes up a green very acrid oil, in Avhich the virtue of the cantharides most eminently resides. So that an ounce of cantharides affords— gross, grains. Reddish yellow bitter extract 3, 0 Yellow oily matter 0 ! 2 Green oily substance, analogous to wax 0 60 Parenchyma, insoluble in water and alcohol 4 0 11 8 0 To form a tincture which unites all the properties of cantharides, a mixture must be made of equal parts of Avater and of alcohol, and the insects digested in it. If this tincture be distilled, the spirit Avhich comes over re- tains the smell of cantharides. If spirit of wine alone be used, it takes up merely the caustic part: hence it appears that the virtue of these in- sects may be increased or diminished according to the ex- igence of the case. The tincture of cantharides may be used with success externally, in the dose of two gross, four gross, one or even tAvo ounces, in rheumatic pains, sciatica, wandering gout, &e. It heats the parts ; accelerates the circulation; excites evacuations by perspiration, urine, or stool, ac- cording to the parts to which it is applied. Mr. Thouvenel tried upon himself the effect of the green waxy matter. When applied on the skin in the dose of nine grains, it raised a blister full of serosity. 2. The wood-lice, millepedes, aselli, porcelli.—This insect is usually found in moist places, under stones, or beneath the bark of old trees. It avoids the light, and endeavours to conceal itself when discovered. When it MILLEPEDES. PRODUCTION OF COCHENILLE. 429 is touched, it rolls up in the form of a globe. This in- sect is used in medicine as an incisive, aperitive, and al- terative remedy. It is prescribed either pounded alive, and put into a proper liquid; or dried and pulverized, m which last form they enter into extracts, pills, Sec. The millepedes are given in the dose of fourteen, fifteen, and twenty grains, or more, according to the exigency of the case. Mr. Thouvenel has given us some information concerning the constituent principles of these insects. He obtained by distillation an insipid or alkaline phlegm: the residue afforded an extractive matter, an oily or waxy sub- stance soluble in spirit of wine 6nly, and marine salt with an earthy and an alkaline base. 3. Cochenille.—Cochenille is a substance used in dy- ing scarlet and purple. It is met with in commerce in the form of small grains of a singular figure, mostly con- vex with little grooves on one side, and concave on the other. The colour of good cochenille is grey mixed with reddish and white. It is at present AA'ell determined that it is an insect. Simple inspection AA'ith a magnifier suffi- cientiy proves this; and the wings and feet of this insect may be developed by exposing it to the vapour of boiling water, or by digesting it with vinegar. The cochenille is collected in Mexico, upon plants to which the names of Indian Fig, Riquette Nopal, are given. These plants bear fruits which resemble our figs; tinge the urine of those who eat them; and probably communicate to the cochenille the property which makes it useful to the dyer. The Indians of Mexico cultivate the nopal near their ha- bitations, and sow as it were the insect Avhich affords the cochenille. They make small nests of moss or fine herbs, put twelve or fourteen cochenilles into each nest, place • three or four of these nests on each leaf of the nopal, anel fasten them there by the prickles of the plant: in the course of a few days, thousands of small insects is- sue out, and fix themselves upon the parts of the leaf which are best sheltered, and afford the most nourishment. The cochenilles are collected several times in the course of the year: and are deprived of life by scalding them, Or by putting them into an oven; arter aa hich they are dried in the sun. Two kinds of cochenille are distin- guished : the one which is produced Avithout culture, and oO PREPARATIONS OF KERMES. is called Sylvestre; and the otlier cultivated, wiiich is called Mestcque. This last is preferred. It has been calculated, in the year 1736, that eight hundred.and eighty thousand pounds Avcight of cochenille Avas annually im- ported into Europe. Mr. Ellis has communicated a very good description of the cochenille to the Royal Society of London. This substance is more especially used in dying: its colour takes readily upon avooI; and the most suitable mordant is the muriate of tin. Mr. Macquer has disco- vered a method of fixing tiiis colour upon silk, by im- pregnating the silk AA'ith a solution of tin before it is plunged into the badi of cochenille; instead of mixing a solution in the baths, as is done for Avoollens. 4. Kermes is a kinel of excrescence, of die size of a juniper-berry, Avhich is gready employed in medicine and the arts. The tiee Avhich bears it is known by the name of Quer- cus Ilex. It grows in hot countries; in Spain, Langue- doc, Provence, Sec. The female of the coccus fixes it- self on the plant; it has no wings, but the male has. When she is fecundated, she becomes large by the deve- lopment of her eggs; she perishes, and the eggs are hatched. It is collected before the development of the eggs; for which purpose, the morning is taken, before the heat has acted upon the eggs. The grains are col- lected and dried, to develop the red colour; they are dien sifted, to separate the powder; and lastly they are sprinkled with good vinegar, to kill the insect, which would otherwise come forth in a short time. Kermes is much used in the arts: it affords a good red, but less brilliant than that of the cochenille. ; ( , l A very celebrated syrup of kermes is made, by mixing three parts of sugar Avith one of the grains of kermes, pulr verized. This mixture is kept for a day in a cool place : the sugar during this time unites with the juice of the kermes; and forms Avith it a liquor Avhich, Avhen draAvn off by expression, has the consistence of syrup. The celebrated confectio alkermes is made with this syrup. The grains of kermes given in substance, from half a scruple to a gross or clram, are celebrated for preventing abortion. GUM LAC. LAKE. 432 The grain and the syrup of kermes are an excellent S'tomachic. 5. Lac, or gum-lac.—This is a kind of wax, collected by red winged ants from flowers in the East-Indies, which they transport to the small branches of the tree where they make their nests. The nests are full of small cells, in which a red grain is found when the mass is broken. This small grain is, to all appearance, the egg from Avhich the flying ant derives its origin. Mr. Geoffroy has proved, in a Memoir inserted among those of the Academy for the year 1714, that this must have been a kind of comb, approaching to the honey- comb of bees, the cells of which are formed of a sub- stance analogous to Avax.* The colouring part of lac may be taken up by water, which when evaporated, leaves the colouring principle disengaged. It is the fine lake used for dying. Lake is imitated by extracting the colouring principle of certain« plants by well-known processes. CHAPTER XI. Concerning some other Acids extracted from the Animal Kingdom. INDEPENDENT of the acids afforded by the various parts of the human body, which have been separately examined by us, we find acids in most insects. Lister points out one which may be extracted from millepedes (Collect. Acad. torn. ii. p. 303). Mr. Bonnet has ob- * For a'description and drawing of the insect which affords the lac, consult Iveir in the Philos. Trans, vol. lxxi. p. 374 ; also maunders, in the same work, vol. lxxix. for the method of purifying the lac, or a short abridgment of both, in Nicholson'> First Principles of Che mistry, p. 490. T. 431 ACID OF MILLIPEDES, OF SILK WORMS, &.C. served that the fluid ejected by the great forked-tail cater- pillar of the avUIoav, was a true aciel, and even very active (Savans Etrangers, torn. ii. p. 276): Bergmann compares it to the most concentrated vinegar. The abbe Boissier ele Sauvages has remarked, that in that illness of the silk- Avorm, Avhich is called muscardin, the humour of die worm is acid. Mr. Chaussier of Dijon obtained an aeid from grasshoppers, from the May-bug, from the kmpy- ris, anel several other insects, by digesting them in alcohol. The same chemist has made an interesting course of ex- periments on the acid of the silk-worm. He gives two methods of cxteacting it. The first consists in bruising the chrv salides, and straining them through a cloth. The fluid Avhich passes is strongly acid; but the acid is weak- ened by various foreign substances, of which it may be cleared by digestion in spirit of wine. The fluid which passes the the filter after this digestion, is of a fine orange colour. More spirit of Avine is to be poured upon it. At every addition of spirit a light whitish precipitate is formed; and the additions of spirit are to be continued until no more precipitate appears. Instead of bruising the chrysalides they may be in- infused in spirit of wine, Avhich elissolves all die acid; and as this acid is less volatile than the spirit, this last may be evaporated, and the residue filtered. By these precautions the acid may be cleared of its spirit of wine and of the mucous matter which was dissolved, but re- mains on the filter. Mr. Chaussier has proved that this acid exists in all the states of the silk-worm, even in the eggs; but that in the egg and in the worm it does not exist in a dis- engaged state, but combined with a gummy glutinous substance. The acid of insects which is best known, and upon which most has been written, is the acid of ants, or the formic acid* This aeid is so far in a disengaged state, that the transpiration of these animals, and their simple contact without any alteration, proves its exist- ence. The authors of the fifteenth century had observed, that the floAA'er of chickory throAATi into an ant-hill becomes as ACID OF ANTS. 433 red as blood.—Sec Langham, Hieronimos Tragus, John Bauhin. Samuel Fisher is the first who discovered the acid of ants, in a course of experiments for the analysis of animal substances by distillation. He even tried its action on lead and iron; and communicated his observations to J. Way, who inserted them in the Philosophical Transactions in die -year 1670. But it was the celebrated Margraaf who more particularly examined the properties of this acid in 1749. He combined it with many substances, and concluded that it greatly resembled the acetous acid. In 1777 this subject was again resumed by Messrs. Ardvidsson and Oerhn; and treated in a manner which leaves little to be desired, in their dissertation published at Leipsic. The ant Avhich affords the greatest quantity of acid, is the large red ant which is found in dry and elevated places. The months of June and July are most favourable for the extraction of this acid: they are then so penetrated with it, that their simple passing over blue paper is suffi- cient to turn it red. Two methods may be used to obtain this acid; dis- tillation and lixiviation. To extract die acid by distillation, the ants are first dried by a gentle heat, and put into a retort, to Avhich a receiver is adapted, and the fire is raised by degrees. When all the acid is come over, it is found in the receiver mixed Avith a small quantity of empyreumatic oil, which floats upon it, and may be separated by a funnel. Messrs. Ardvidsson and Oerhn obtained, in this man- ner, from each pound of ants, seven ounces and a half of an acid whose specific gravity, at the temperature of fifteen degrees, Avas to that of water as 1,0075 to 1,0000. In the process of lixiviation, the ants are Avashed in cold water; and boiling water is afterwards poured over them, which is filtered -when cold. More boiling Avateris poured over the residue, and likewise filtered when cold. By* this means one pound of ants affords a pint of acid as strong as vinegar, and of a greater specific gravity. Vol. IL 3 I 434 ACID OV ANTS. Messrs. Ardvidsson and Oerhn are of opinion that tins acid might be substituted instead of vinegar for domestic uses. The acid obtained by these processes is never pure; but it may be purified by repeated distillations, Avhich dis- engage the ponderous and volatile oil, and render the acid as clear as Avater. This acid, Avhen rectified by this pro- cess, Avas found by Messrs. Ardvidsson and Oerhn to have a specific gravity of 1,0011 to 1. The acid of ants may likewise be obtained by placing linen cloths impregnated with alkali in an ant-hill. From these the formiate of pot-ash, of soda, and ammoniac, may be obtained by lixiviation. The formic acid has some re- semblance to the acetous acid; but the identity of these tAvo acids has not yet been proved. Mr. Thouvenel found more analogy betAveen it and the phosphoric acid: but all this Avants proof. The formic acid retains water Avith so much force, that it cannot be entirely deprived of it by distillation. When it is exceedingly pure, its specific gravity is to that of wa- ter as 1,0453 to 1. It affects the nose and the eyes in a peculiar man- ner, which is not disagreeable. Its taste is penetrat- ing and burning Avhen pure, but agreeable Avhen diluted with water. It possesses all the characters of acids. When boileel with the sulphuric acid, it turns black as soon as the mixture is heated. White penetrating a\ip< irs arise; and when it boils a gas is emitted, Avhieh u; .ites difficultly Avith distilled water, or with lime-water. The formic acid is decomposed in this operation, for it is ob- tained in less quantity. The nitric acid distilled from it, destroys it completely; a gas arises which renders lime-Avater turbid, and is diffi- cultly and sparingly soluble in Avater. The muriatic acid only mixes Avith it, but the oxige- nated muriatic acid decomposes it. Messrs. Ardvidsson and Oerhn have determined the affinities of this acid with various bases in the follow- lowing order: baFytes, potash, soda, lime, magnesia, ammoniac, zinc, manganese, iron, lead, tin, cobalt, AV1MAL JTiTREFACTJON. 433 copper, nickel, bismuth, -silver, alumine, essential oils, water. This acid mixes perfectly with spirit of wine. Jt Unites difficultly with the fixed oils, and with the volatile oils, by the assistance of heat It attacks soot; assumes a fawn eolour; and lets fall a brown sediment as it cools, which by distillation affords a liquor of a yellowish colour and a disagreeable smell, accompanied with elastic va- pours. CHAPTER XI. Concerning Putrefaction. EVERY livmgbody, Avhen once deprived of life, per- forms a retrograde process, and becomes decompo- sed. This decomposition is called Fermentation in vege- tables, and Putrefaction in animal substances. The same causes, the same agents, and the same circumstances, determine and favour the decomposition of vegetables and animals, and the difference of the productions Avhich are obtained, arises from the difference of the constituent parts of each. Air is the principal agent of animal decomposition, but water and heat prodigiously facilitate its action. " Fer- mentatio ergo definitur quod sit corporis densioris rarefac- tio, particularumque aerearum interpositio : ex quo con- tVuditur debere in aere fieri nee nimium frigido, ne rare- factio impediatur; nee nimium calido, ne partes raribiles expellantur."—Becher, Phys. Sub. lib. i. s. 5. p, 313. edit. Francofurti. An animal substance may be preserved from putrefac- tion by dqoriving it of the contact of air; and this pro- cess may be accelerated or retarded by varying or modi* fying the purity df the same fluid. 436 ANIMAL FUTREFACTIO*. In those circumstances Avhercin Ave see putrefaction dc-* vcloped Avithout the contact of atmospherical air, uic ef- fect is produced by the Arater which impregnates the ani- mal substance, AA'hich becomes decomposed, and affords the element and the agent of putrefaction. Hence no doubt it arises that putrefaction is observed in flesh closed in a vacuum.—See Lyons, Tentamen de Putrefactione. Moisture is likewise an indispensable requisite to faci- litate putrefaction; and any substance may be defended from this change by completely drying it This, waa per- formed by Villaris anel Cazalet of Bordeaux, by means of stoves. The meat thus prepared Avas preserved for seve- ral years Avithout having contracted any bad flavour. The sands and light porous earths preserve the bodies of men only by vinue of the property of exhausting their juices, anel drying the solids. From this cause it is that entire caravans have been discovered in Arabia, consisting of men and camels perfectly preserved in the sands under Avhich the impetuous winds have buried them. In the li- brary of Trinity College of Cambridge, in England, a human body may be seen perfectly preserved, which was found under the sand in the island, of Teneriffe. To* much humidity impedes putrefaction, according to the ob- servation of the celebrated Becher: " Nimia quoque hu- miditas a putrefactione impedit, prout nimius ealor; nam corpora in aqua potius gradatim consumi quam puiresce- re, si nova semper affluent sit, experientia docet: unde longo tempore integra interdum submersa prorsus a pu- trefactione immunia vidimus; adea ut nobis aliquandt speculatio occurreret, tractando, tali modo caelavera ana- tomiae subjiciendo, quo diutius a faetere et putrefactione immunia forent." Phys. Sub. lib. i. s. 5. cap. 1. p. 277. In order therefore that a body may putrefy, it is neces- sary that, it should be impregnated Avith Avater, but not that it should be inundated. It is likewise necessary tbat this Avater should remain in the texture of the animal bo- dy, Avithout being renewed. This condition is requisite —1. To dissolve the lymph, and to present to the air the most putresciblc substance with the greatest extent of sur •£tce, 2. In order that the water may itself become de- composed, and by this means afford the putrefactive prin- ciple. Putrefaction is retarded and suspended .by baking, ANIMAL PUTREFACTION. 437 because the flesh is dried, and by that means deprived of the humidity, which is one of the most active principles of its decomposition. A moderate degree of heat is likewise a condition fa- vourable to the animal decomposition. Bv this heat the affinity of aggregation between the parts is weakened, and consequently they assume a stronger tendency to new combinations. Hence it arises that flesh meat keeps longer during the winter than the summer, and better in cold than in hot countries. Becher has given a very in- telligent sketch of the influence of temperature on animal putrefaction : " Aer calidus et humidus maxime ad pu- trefactionem facit .... corpora frigida et sicca difficul- ter, imo aliqua prorsus non putrescunt, quae ab imperitis proinde pro Sanctis habita fuere; ita aer frigidus et sic- cus, imprimis calidus et siccus, a putrefactione quoque preservat; quod in Hispania videmus, et locis aliis calieiis, sicco, calidi aere praeditis, ubi corpora non putrescunt et resolvantur; nam cadavera in oriente in arena, imo apud nos arte in furnis, siccari, et sic ad finem mundi usque a putredine preservari, certum est: intensumquoque frigus *sl prutredine preservare; unde corpora Stockholmiae tota hyeme in patibulo suspensa sine putredine animadverti* mus." Phys. sub. 1. i. cap. 1. * Such are the causes which are capable of determining and favouring putrefaction; and hence we may perceive the best means of preventing, increasing, or modifying k at pleasure. A body will be preserved from putrefaction *by depriving it of the contact of atmospherical air: for this purpose nothing more is required than to place the body in a vacuum, or to envelop it in a covering which may defend it from the immediate action of the air; or else to envelop it in an atmosphere of some gaseous sub- stance which does not contain vital air. We shall ob- serve, on this subject, that the effects observed in flesh exposed in the carbonic acid, nitrogene gas, &c. are re- * ferable to a similar cause ; and it appears to me that it is without sufficient proof that a conclusion has been drawn, that these same gases, internally taken, ought to be con sidered as antiseptic; because, in the cases we have men- tioned, diey act only by defending the bodies they sur round from the contact of vital-Air, whi(»h is the principle 4£8 ANIMAL PUTREFACTION. of putrefaction. Putrefaction may be favoured by keep. ing bodies at a suitable temperature. A degree of heat from fifteen to twenty-five degrees diminishes the adhe- sion of the parts, ana favours die action of the air: but if the heat be greater it volatilizes the aqueous principle, dries the solids, and retards the putrefaction. It is ne- cessary, therefore, for the decomposition of an animal— 1. That it haAre the contact of atmospheric air; and the purer this air is, the more speedy will be the putrefaction. 2. That it be exposed to a moderate degree of heat. 3. That its texture be impregnated with humidity.—The experiments of Pringle, Macbride, Gardane, have like- wise sheAvn us, that putrefaction may be hastened by sprinkling the animal substances Avith AA-ater containing a small quantity of salt; and it is to a like cause that we ought to refer several processes used in kitchens to pro- duce this effect in food, as well as in the preparation of cheese, the curing of tobacco, the making of bread, See. Becher expresses himself as follows on the causes AA'hich produce putrefaction in living bodies:—" Causa putrefactionis primaria dcfectus spiritus vitalis balsamirri est; secundaria, deinde, aer externus ambicus, qui inter- dum adeo putrefaciens et humidus-calidus est, ut super- stitem in vivis etiam corporibos balsaminum spiritum vin- cat, nisi confortando augeatur; ex quo colligi potest, preservantia a putredine subtilia ignea oleosa esse debere." —This celebrated chemist concludes, from the same principles, that ligatures, copious bleedings, or any de- bilitation whatever, determines putrefaction. He like- wise thinks that astringents oppose putrefaction only by condensing the texture of the animal parts; for he consi- ders rarefaction or relaxation as the first effect of putre- faction. He thinks that spirituous liquors act as antipu- trescent merely by'animating and stimulating the vis vitae. He affirms that the use of salted meats, which heat much, assisted by the moisture very common in ships and sea ports, produces the scurvy; and he observes, with rea- son, that the tendency and effect of putrefaction are dia- metrically opposite to those of generation: " nam sicut in. generatione partes coagulantur et in corpus formantur, ita in putrefactione partes resolvuntur et quasi informes fiunt." ANIMAL PUTREFACTION. 439 As the phenomena of putrefaction vary according to the nature of the substances themselves, and the circum- stances which .accompany this operation, it follows that it must lie very difficult to describe all the phenomena AA'hich it exhibits. We shall therefore endeavour to trace only tiiose wiiich appear to be the most constant. Every animal substance exposed to the air at a tempe- rature alaoye ten degrees of Reaumur, and moistened with its own serous humour, putrefies ; and the progress of tins alteration appears in the following order. The colour first becomes pale; its consistence dimi- nishes ; its texture becomes relaxed;. the peculiar smell of fresh meat elisappears, and is succeeded by a feint and disagreeable smell. The colour itself at this time inclines to blue; as we see in game Avhich begins to turn, in wounds which fall into suppuration, in the various parts threatened with gangrene, and even in that putrefaction of the curd Avhich forms cheese. Most of our food suf- fers the first degree of putrefaction before Ave use it. After this first period the animal parts become more and more softened, the smell becomes fetid, and the co- lour of an obscure brown; the fibrous part easily breaks, the texture becomes dry, if the putrefaction be carried on in the open ak ; but die surface becomes covered with small drops of fluid, if the decomposition be made in ves- sels wiiich oppose its evaporation. To this period succeeds that which most minutely cha- racterizes animal putrefaction. The putrid and nauseous smell Avhich Avas manifested indie second degree, becomes mixed Avith a smell of a more penetrating kind, arising from the disengagement of ammoniacal gas; die mass becomes still less and less consistent. The last degree of decomposition lias its peculiar cha- racters. The smell becomes faint, nauseous, anel ex ceedingly actiA'e. This, more especially, is contagious, and transmits the seeds of infection to a great distance : it is a tnie ferment, which deposites itself upon certain boelies, to appear again at long intervals. Van SAvieten reports, that the plague having appeared at Vienna in 1677, and having again appeared in 1713, the houses Avhich had* been infected at its first appearance Avere like- wise infected at the second. Van Helmont asserts that a wo AXTMAL PUTREFACTION. woman contracted an anthrax at the extremity of her fin* gers, in consequence of having touched papers impregnat- ed AAith pestilential virus. Alexander Benedictus has written that pilloivs reproduced the contagion seven years after having been infected; that cords had remaincel in- fected for thirty years, and likeAvise communicated it, ac- coreiing to Forestus. The plague at Messina Avas for a tang time concentrated in the Avarehouses where merchan- dise AA'as inclosed Avith suspected bales. Mead has trans- mitted the most alarming facts concerning the durable- impression of contagion. When the putrefying substance is in its last stage, the fibrous texture is scarcely discernible, and has no longer any appearance but that of soft, disorganized, and putrid mass. Bubbles are seen to escape from the surface of this matter; and the Avholc ends by its drying, and be- coming reduced to an earthy matter, which is friable when taken betAveen the fingers. We do not speak of the production of worms; because it appears to be proved that they owe dieir origin only to the flies which endeaA'our to deposite tiieir eggs upon such bodies as are best suited to support die young they con- tain. If flesh meat be well Avashed, and left to putrefy under a sieve,, it will pass through all the degrees of pu- trefaction Avithout the appearance or worms. It has been observed that Avorms arc of a different species, according to the nature of the disease, and the kind of animal which putrefies. The exhalation Avhich arises from bodies, in these different cases attracts different species of insects, according to its nature. The opinion of those who be- lieve in spontaneous generation, appears to me to be con- trary to the experience and Avisdom of nature, which cannot have committed the reproduction and number of the species to chance* The progress of nature is the same for all the classes of individuals; and since it is proved that all the'known species are reproduced in one and the same manner, hoAV can we suppose mat nature departs from her plain and general laAvs for the small number of individuals AA'hose generation is less known t© Us? ANIMAL PUTREFACTION. 441 Becher had the courage to make observations, du- ring the course of a year, upon the decomposition of a carcass in the open air; and to observe all the phenome- na. The first vapour which rises, says he, is subtile anel nauseous : some days after, it has a certain sour and pe- netrating smell. After the first weeks, the skin becomes covered with a down, and appears yellowish; greenish spots are formed in various places, Avhich afterwards be- come livid and black; a thick mossy or mouldy substance then coveTs the greatest part of the bexly; 'the spots open, and emit a sanies. Carcases buried in the earth present very different phe- nomena ; the decomposition in a burying-ground is at least four times as slow. It is not perfectly endeel, according to Mr. Petit, till three years after the body has been interred, at the depth of four feet; and it is slower in proportion as the body is buried at a greater depth. These facts agree with the principles Avhich Ave have already establish- ed for bodies buried in the earth, and subjected to laws of decomposition very different from those Avhich take place in bexlies exposed to the open air. In this case the decomposition is favoured by the waters Avhich filter through the earth, and dissolve and carry with them the animal juices. It is also favoured by the earth, which absorbs the juices Avith more or less facility. Messrs, Lemery, Geoffroy, and Hunaud have proved that argilla- ceous earths exert a very slow action upon bodies; but when the earths are porous and light, the bodies then dry very speedily. The several principles of bodies absorbed by the earth, or carried by the vapours, are elispersed through a great space, imbibed by the roots of vegetables, and gradually decomposed. This is what passes in bu- rying-grounds in the open air; but it is very far from be- ing applicable to the sepulchres which are made in churches and covered places. Here is neither water nor vegetation; and consequently no cause which can carry away, dissolve, or change the nature of the animal fluids: and I cannot but applaud the wisdom of government, Avhich has prohibited the burying in churches; a practice which was once a subject of horror and infection; Vol. II. .3K 442 ANIMAL PUTREFACTION. The accidents which have happened at die opening of graves and vaults are but too numerous, to render any apology necessary for our speaking a feAv words respect- ing die method of preventing them. The decomposition of a body in the bow els of the earth can never be dangerous, provided it be buried at a sufficient depth, and that the graA-e be not opened before its entire and complete decomposition. The depth of the grave ought to be such that the external air cannot penetrate it; that the juices Avith Avhich the earth is im. pregnated may not be conveyed to its surface; and that the exhalations, vapours, or gases, which are developed or formed by decomposition, should not be capable of forcing the earthy covering which detains them. The na- ture of the earth in which the grave is dug, influences all its effects. If the stratum Avhich covers the body be ar- gillaceous, _ the depth of the grave may be less, as this earth difficultly affords a passage to gas and vapour; but in general it is admitted to be necessary that bodies should be buried at the depth of five feet, to prevent all these unhappy accidents. It is likeAvise necessary to attend to the circumstance, that a grave ought not to be opened be- fore the complete decomposition of the body. This de- composition, according to Mr. Petit, is not perfect until the expiration of three years, in graves of four feet depth; or four years, Avhen they are six feet deep. This term affords many varieties, according to the nature of the earth, and the constitution of the subjects buried in it; but we may consider it as a medium. The pernicious custom which allows a single grave to families more or less numerous, ought therefore to be suppressed; for in this case the same grave may be opened before the time prescribed. These are abuses which ought to occupy the attention of government; and it is time that the van- ity of individuals should be sacrificed to the public safety. It is likewise necessary to prohibit burying in vaults, and even in coffins. In the first case, the principles of the bodies are spread into the air, and infect it; in the se cond, their decomposition is sloAver and less perfect. If these precautions be neglected; if the dead bodies be heaped together in too confined a space; if the earth be not proper to absorb the juices, and decompose them: MINERAL AVATERS. 443 if the grave be opened before the entire decomposition of the body—unhappy accidents will, no doubt, be pro- duced; and these accidents are but too common in great towns where every wise precaution is neglected. An in- stance of this happened Avhen the ground of the church of St. Benoit at Paris was dug up a few years ago: a nauseous vapour was emitted, and several of the neigh- bours Avere affected by it. The earth Avhich was taken out of this grave was unctuous, viscid, and emitted an infectious smell. Messrs. Maret and Navier have left us several similar observations. r-p] Concerning Mineral Waters* 'HE name of Mineral Water is given to any Avater. t. whatever which is sufficientiy loaded Avith foreign principles to produce an effect upon the human body, dif- ferent from that which is produced by the Avaters com- . monly used for drink. Men, doubtless, were not long in attending to the dif- ferences of waters. Our ancestors appear even to have been more strictly attentive than ourselves to procure wholesome drink. It was almost always the nature ot the Avater Avhich determined their preference in the situa- tion of towns, the choice of habitations, and consequently the union of citizens. The smell, the taste and more especially the effects of Avaters upon me animal economy, . have been thought sufficient, dui&g a long time to de- termine their nature. We ma/ see, in the writings of Hippocrates, how much observation and genius are ca- pable of performing in subjects of this nature. This Erea? man, of Avhom it Avould afford but a very imperfect Sea to insider him pierely as the Father of Medicine Avas so well acquainted with the influence of water upon me human body, that he affirms that the mere quality 444 EXAMINATION 0* q£ their usual drink is capable of modifying and produce ing a difference betAA'cen men; and he recommends to young, physicians to attend more particularly to die na- ture of the. waters their patients ought to use. We see tile Romansj who were frequently under the necessity of settling in parched climates, spared no exertion* to pro- cure Avholesome Avater to their colonies. Tlie famous aqueduct Avhich, carried the water of Uzes to Nismes, is an unequivocal proof of this; and we still possess several mineral springs at Avhich they formed colonies, for the ad- vantage of the badis. It was not till near the seventeenth century that die ap- plication of chemical methods to the examination of wa- ters Avas first made. We are indebted to the present re- A'olution of chemistry for the degree of perfection to Avhich this analysis has been carried. The analysis of waters appeal's to me to be necessary, in order— 1. That Ave may not make use of any water for drink but such as is Avholesome. 2. That avc may become acquainted with those which possess medicinal virtues, and apply them to the uses to which they are suited. 3. To appropriate to the different works or manufacto- ries that kind of water, Avhich is the best calculated for :heir respective purposes. 4. To correct impure Avaters, or such as are either im- pregnated Avith any noxious principle, or charged with any- salt 5. To imitate the knoAvn mineral waters, in all places and at all times,. The analysis o£ mineral waters is one of the most diffi- cult problems of Chemistry. In order to make a per- fect analysis, it is necessary to be aAvare of all the distinct- ive characters of the substances which may be held in solution in any water. The operator must be acquainted Avith the means of scparatVtg from an almost insensible residue the different substances which compose it. He must be able to appreciate the mature and quantity of the products Avhich are carried off by evaporation; and like- wise to ascertain whether certain compounds are not form- MINERAL WATERS. 445 ed by the operations of his analysis, Avhile others may be decomposed. The substances contained in waters are held either in suspension or in solution. 1. Those substances Avhich are capable of being sus- pended in waters are clay, silex in a state of division, cal- careous earth, magnesia, &c.* Those which are soluble are, pure air, the carbonic aciel, pure or compound alkalis, lime, magnesia, the sulphates, the muriates, the extractive matter of plants, hepatic gas, &c. The most ancient, the most general, and the most simple division of mineral Avaters, is that which distin- guishes them into cold waters, and hot or thermal vvaters, accordingly as their temperature is the same, or exceeds that of common water. A division founded on the several qualities of these waters, will arrange them in four classes. I. Acielulous or Gaseous Waters.—These are known by their penetrating taste; the facility with which they boil; the disengagement of bubbles by simple agita- tion, or even by mere standing; the property of red- dening the tincture of turnsol; the precipitating lime water, &c. They are either cold or hot. The first are those of Seitz, of Chateldon, of Vals, of Perols, &c. The second are those of Vichi, of Montd'or, of Chatelguy- on, &c. II. Saline Waters, properly so called.—These are cha- racterised by their saline taste, which is modified accord- ing to the nature of the salts they contain. The salts most generally found in waters are, the muriate of magnesia. the sulphates of soda, of lime, Sec. Our Avaters of Bal- aruc, of Yeuset, &c. are of this nature. III. Sulphureous Waters. These waters have long been considered as holding sulphur in solution. Messrs. Venel and Monnet opposed this assertion. Bergmann has proved that most of these Avaters are merely impreg- nated with hepatic gas. It appears, however, mat there are some which hold true liver of sulphur in solution, * Silex is soluble in some waters, as in those of Carisbad in Boh<, nva, and Geyser in Iceland.-*—.^m. Ed. IK) MINERAL AVATERS. such as those of Bareges and of Cotteret ; Avhercas the Avaters of Aix la Chappellc, Montmorency, &c. are of the nature of those mentioned by Bergmann. We may, Avith Mr. De Fourcroy, call the first by the name of Hepatic Waters, and the latter by the name of Hepatized Waters. This class is known by the smell of rotten eggs which they emit. IV. Martial Waters.—These have the property of ex- hibiting a blue colour by the solution of prussiate of lime: they have besieles a very evident astringent taste. The Iron is held in solution either by the carbonic or the sul- phuric acid. In the first case the acid is either in excess, anel the AAater has a penetrating subacid taste, as the wa- ters of Bussang, Spa, Pyrmont, Pougue, &c.; or the acid is not in excess, and consequently the Avaters are not acidulous; such arc the Avaters of Forges, CondS, Auniale, &C. Sometimes the iron is combined Avith the sulphuric acid, anel the Avater holds in solution a true sulphate of irdn.- Mr. Opoix admits this salt in the Avaters of Pro- vins; and those of Rougne near Alais are almost satu- rated with it. Mineral waters of this quality are frequently found in the vicinity of strata of pyrites. There are se- veral near Amalou, and in the diocese of Uzes.* There are some waters Avhich may be placed indiscri- minately in several of the classes. Thus, for example, there are saline waters which may be confounded with ga- - * The mineral waters of the United States, may be divided into llie acidulous, the hepatic or sulphureous, and the chalybeate. The principal ingredients of the Balls-town and Saratoga waters, in the state of New-York, are carbonic acid gas, sulphate and car- bonate of iron and lime. The spring of Harrowgate in Pennsyl- \»ania, that in the town of Greenbush, county of Rensaeller, New- York, the two in Greenbriar, and Monroe county, Virginia, and ,he one on the eastern side of the Paris mountain, South-Carolina, are impregnated with sulphurated hydrogene gas, or hydrogene gas holding sulphur in solution. The yellow spring about twenty-nine miles west of Philadelphia, and the one near Bristol, Pennsylvania, are slightly impregnated aIiIi iron. There are also warm springs in the state of Virginia, the tem- perature of which are, from 102° to 108° of Fahrenheit's thermo- meter.— Am. Ed. MINERAL WATERS. 447 seous waters, because air is constantly disengaged from them. The Avaters of Balaruc are of this kind. We do not comprehend among mineral Avaters those which suffer gas to escape through them, Avithout com- municating any characteristic property; such as the burn- ing spring of Dauphiny, &c. When the nature of any water is ascertained, its ana- lysis may be proceeded upon by the union of chemical and physical means. I call those methods phy.sical, which are used to ascertain certain properties of water Avithout decomposing them. These methods are, for the most part, such as may be carried into effect at the spring itself. The appearance, the smell, and the taste afford indica- tions by no means to be neglected. The limpidity of any Avater indicates its purity, or at least the accurate solution of the foreign principles it may contain; an imperfect transparency denotes that foreign substances are suspended. Good Avater has no smell: the smell of rotten eggs denotes liver of sulphur, or he- patic gas; a subtile and penetrating smell is proper to aci- dulous Avaters; and a fetid smell characterizes stagnant waters. The bitterness of waters in general depends on neutral salts. Lime, and the sulphates, give them an austere taste. It is likewise of importance to ascertain the specific gravity of the Avater, wiiich may be done either by means Of the areometer, or by the comparison of its weight with diat of an equSl volume of distilled Avater. The degree of heat must likeAvise be taken by means of a good mercurial thermometer. Thermometers made with spirits of wine ought to be rejected; because the dilatation, after the thirty-second degree of Reaumur, is extreme, and no longer corresponds Avith the temperature of the water. It is interesting to calculate the time Avhich the water requires to become cool, in comparison Avith distilled Avater raised to the same degree of temperature. Notice must likewise be taken whether any substance ex- hales, or is precipitated by the cooling. The observer ought likeAvise to enquire Avhether rains, dry seasons, or other variations of the atmosphere, have any influence on the temperature or quantity of water of 448 Examination oj the spring. If these causes act upon the spring, its vir tue cannot but vary exceedingly. This is die cause why certain mineral waters are more highly charged with these principles in one year than in another; and hence also it arises that certain Avaters produce wonderful effects in some years, though, in other seasons their effects are tri- fling. The celebrated De Haen, Avho analysed for seve- ral successive years all the waters in the neighbourhood of Vienna, never found them to contain the same princi- ples in the same proportion. It would therefore be an in- teresting circumstance, if, at the time of taking up or bottling of these Avaters, a skilful physician were to ana- lyse them, and publish the result After diese preliminary examinations have been made at the spring, further experiments must be made accord- ing to the methods of chemistry. These experiments ought to be performed at the spring itself : but if this cannot be done, new botties may be filled with the Avater; and, after closing them very accurately, they may be carried to the laboratory of the chemist, Avho must proceed to examine them by re-agents, and by the me- thod of analysis. I. The substances contained in water are decomposed by means of re-agents; and the new combinations or pre- cipitates which are formed, immediately point out the na- ture of the principles contained in the waters. The most efficacious and the only necessary re-agents are the follow- ing: 1. Tincture of turnsol becomes red by its mixture with acidulous waters. 2. Prussiate of lime, and that of ferruginous potash not saturated, precipitate the iron contained in a mineral Avater of a blue colour. 3. The very concentrated sulphuric acid decomposes most neutral salts; and forms with their bases salts very Avell known, and easily distinguished. 4. The oxalic acid, or acid of sugar, disengages lime from all its combinations, and forms with it an insoluble salt The oxalate of ammoniac produces a more speedy ef- fect ; for, by adding a few crystals of this salt to water MINERAL WATERS. 449 charged Avith any calcareous salt, an insoluble precipitate is instantly formed. 5. Ammoniac or volatile alkali affords a beautiful blue colour with the solutions of copper. When this alkali is very pure, it does not precipitate the calcareous salt, but decomposes the magnesian only. In order to have it in a highly caustic state, a syphon may be plunged in the mineral water, and ammoniacal gas or alkaline air passed through it. The Avater ought to be kept from the contact of the atmosphere, which otherwise might occasion a pre- cipitation by virtue of its carbonic acid. 6. Lime Avater precipitates magnesia; and it likewise precipitates the iron from a solution of sulphate of iron. 7. The muriate of barytes detects the smallest parti- cle of sulphuric salts* by the regeneration of ponderous spar, Avhich is insoluble, and falls doAvn. 8. Alcohol is a good re-agent, on account of its affi- nity with 'water. The nitrates of silver and of mercury may likeAvise he employed to decompose sulphuric or muriatic salts. II. These re-agents, indeed, point out the nature of the substances contained in any Avater; but tiiey do not exhibit their accurate proportions. For this purpose we are obliged to have recourse to other means. There are tAvo things to be considered in the analysis of any water : 1. The volatile principles. 2. The fixed principles. < 1. The volatile principles are carbonic acid gas and hepatic gas. The proportion of carbonic acid may be ascertained by various processes. The first, Avhich has been used by Mr. Venel, consists in half filling a bottle Avith the gaseous water intended to be analysed. A blad- der is then to be tied upon the neck of the bottle, and the water agitated. The air Avhich is disengaged inflates the bladder; and bv that indication an estimate may be made of its quantity.' This process is not accurate; because agitation is not sufficient to disengage the whole oi the carbonic acid. Neither is the evaporation of the water in the pneumato-chemical apparatus much more exact; be- cause the Avater which rises with the air combines again Avith it, and the gaseous product consists only of a pari 9f the gas contained in the water. The precipitation by Vol. II. 3 L 450 EXAMINATION OF lime-water appears to me to be the most accurate process. Lime-Avater is poured into a determinate quantity of the Avater, until it ceases to cause an)' precipitite. This pre- cipitate being very accurately Aveighed, 4° parts of the Avhole must be deducted for the proportion in Avhich Ava- ter anel earth enter into it; and the remainder is the acid contained in this carbonate of lime. Hepatic gas may be precipitated by the very concen- trated nitric, aciel, according to the experiments of Berg- mann. The oxigenated muriatic acid has been proposed by Scheele; and Mr. De Fourcroy has pointed out the sul- phureous acid, the oxides of lead, and other re-agents, to precipitate the small quantity of sulphur held in solu- tion in hepatic gas. 2. E\ aporation is commonly used to ascertain the na- ture of the fixed principles contained in any mineral wa- ter. Vessels of earth or porcelain are the only kind suit- able to this purpose. The evaporation must be moderate'; for strong ebulli- tion volatilizes some substances, and decomposes others. In proportion as the evaporation proceeds, precipitates are afforded, Avhich Mr. Boulduc proposes to take out INDEX. A. ./\.CIDS, vegetable Page. - 270 Alkalis 281 Antimony 32 Aroma 311 Arsenic 14 B. Balsams Bismuth Bile Blood c. Calculus of the bladder Camphor Caoutchouc ( Cerium Chromum Cobalt Colouring principles Columbium - Copper Digestion D. F. Eat Fecula of vegetables fermentation Gold 244 28 388 381 G. H. Page. 153 Heat, action of on vegetables Honey - - 297 I. Iron Iridium Lead 255 250 191 190 22 283 191 116 370 384 256 345 M. Manganese Mercury Milk Mineral waters Molybdena Mucilage N. Nickel Nickoiinum Oils a 79 185 59 51 130 373 443 180 218 27 19S 454 INDEX. Obmium Opium Palladium Phosphorus Pit coal Platina Plumbago Pollen Putrefaction Resins Rhodium P. A'S !W Page. 186 305 ( 184 30'J 325 164 91 294 435 239 R. S. Silver - - 143 Stones which have fallen from the earth (note) - 81 Sugar - - 264 Tin Titanium Tungsten (Tellurium Uranium Urine Tantalium Tartar 191 358 u. Page. 70 190 172 189 109 400 V. Varnish l- " - 25*4 Vegetable gluten - 2,61 Vegetables, structure of - 202 Vegetables, decomposition of - - 338 Volcanos . - - 332 w. Wax - - ,296 Water, action of on vegeta- bles Wolfram - - 176 Zinc cdr Dr. Woouhouse's Lectures on Chemistry, com- mence every year in the city of Philadelphia, on the first Tuesday in November. He possesses a complete apparatus ; and during the course, several thousand brilliant experiments are exhi- bited. Specimens of the different earths, salts, metals, &fc arc shewn to his class. Dr. W. will give all the information in his power, to any gentleman, concerning any mineral sent to him, and when necessary will make a complete analysis of it, free of any expense. fPifcfiJL __| ' .ViX ^7d. C*tLleE l?07 , *£.%'