*> */ 1 B5A AS. INTRODUCTION TO DESIGNED FOR BEGINNERS IN THE SCIENCE. FROM THE LATEST AND MOST APPROVED AUTHORS TO WHICH IS ADDED A Dictionary of Terms. BY JOHN RUGGLES COTTING, -■urn LECTURER ON NATURAL AND EXPERIMENTAL PHILOS- OPHY, CHEMISTRY AN]| B(*a|4'. |5 \ j£> VT (VFC. 8— tJK3|_ BOSTON, inf^Q ij^ p PUBLISHED BY CHARLES EWER...,NO.'SI, COP.-VIULL May, 1822. Anne.*, JO DISTRICT OF MASSACHUSETTS....to wit . District Clerk's Office. BE IT REMEMBERED. That on the Eighteenth day of May, A. D. 182J, in the forty sixth Year of the Independence of the United States of America, JOHN RUGGLES COT TING, of the said District, has deposited in this Office, the Tit'e of a B jok, the right whereof he claims at Author, in the words follow- inc. to wit : " An Introduction to Chemistry, with Pi optical Questions: des'gned for Bo ginners 'n the Science. From Uie latest and most approved Authors. To which i'added, A Dictionary of Terms, by John Ruggles Cotting, Lecturer on Kattirdl and Experimental Philosophy, Chemistry and Botany." In conformity to the Act of the Congress of the United States, entitled " An Art forthe encouragement of Learning, by seeming the Copies of Maps, Charts ami Books, to the Authors and proprietors of such Copies, during the times there- in mentiomd :" and also to an Act entitled. " An Act srtpplementary to an Act, i>ntitltd An Act forthe encouragement of Learning,by securing the Copies of Maps, Charts and Books, to the Authors and Proprietors of such Copies during the times therein mentioned ; and extending the Benefits thereof to {he Arts of Dtsigning, Engraving and Etching Historical, and other Prints." tvn \v r»AVf«s 5 Clerk of the District 3SO. W.DAVIS. ^ of Massachusetts true &L greene......Printers. PREFACE. I HE science of chemistry is considered as a part of a polite anil liberal education for both sexes, and is taught in most of the literary institutions of our country. Its util- ity and the interest which it is calculated to excite, can- not fail to recommend it to the attention of every inquis- itive mind. It is so intimately connected with the phys- ical sciences in general, that no one of them can success- fully be cultivated entirely independent of it. Chemistry is not confined to one department of nature it takes a wide range through all the works of creation, and subjects nil material bodies to its laws. "The solid matters comprising the terrestrial mass of the globe we inhabit; the aqueous fluids which penetrate its cavities or float on its surface; the more gaseous fluids which surround this ponderous mass ; the agencies of heat, light and other fleeting substances expanded through the mighty .space, are subjects upon which the chemical phi- losopher may dwell with infinite profit and delight." Chemistry extends itself into the minute concerns of active life, and is the fostering hand of innumerable im- portant arts, and the various discoveries made in the science are so many acquisitions to those arts. The science is no longer, as formerly, confined to the laboratory of the artist, but it ranks among the first in philosophical research. It has been enriched, and is continually undergoing improvements by philosophers, ia every part of Europe. Works on chcr istry are daily IV. rRLFACE. issuing from the press, which are excellent in them' ^lves, and have a tendency to advance the student in the knowledge and improvement of the science. But there are few that are calculated, in every respect, for beginners. The Conversations on Chemistry, by Mrs. Bryan, is a vory useful and popular work, and has been through many editions both in Europe and America. The subjects are treated in a very pleasing and familiar manner. Great obligations are due to the amiable authoress for the good fhe has done to the cause of the science. But the expe- diency of adapting this as an elementary work, at the present time is questioned by many instructors, as great im- provements and discoveries have been made in the science rince that work was written ; many subjects are there inserted which have no relation whatever to this coun- try, r.nd the colloquial manner of treating the subjects necessarily occupies a great portion of the book, which might otherwise be appropriated to subjects of more im* portance. Works which treat of the rudiments of chemistry should be perspicuous, as it embraces a variety of sub- jects, and those, owing to the revolutions which the sci- ence is continually undergoing,are too often involved with other matters, not immediately connected with first princi- ples. The consequence of which is, the student finding many objects arresting his attention, at once, all equally gratifying and attractive, looses sight of those elements, by which only, a permanent foundation can be laid. The author is no advocate for those who pretend to dis- play all the elegance of the temple of science at once, in. to which the novice is introduced without preparation or ceremony, where idleness and industry are permitted to participate equally in the same rewards, lie believes PREFACE that the candidate for excellence must proceed with cau- tion, perseverence and labour; that there is but one road to science, which at first is rugged, steep and difficult; that as we advance, we acquire strength to encounter new difficulties, till finally we are qualified to relish the sub- lime beauties that await the persevering and industri- ous. We ought always to bear in mind the maxim, " Radix doctrinae amara fructus dulcls." An attempt has been made in the following work ; to bring the principles of chemistry into as small a compass as possible, and in a concise manner to exhibit the vari- ous subjects treated of by the most eminent chemical writers of the present day. The work is designed for beginners in the science, it became therefore, necessary to consult the interests both of the instructor and pupil. Few chemical works appear to have had this object in view. Authors have gone upon the supposition that the learner has already become acquainted with the elements, and is qualified to pursue it, through all the intricate subjects, in the elaborate works of the present day. The consequence is, that ei- ther much time is lost in attempting to acquire a knowl- edge of the subject, or an aversion is contracted which ends in a total neglect of this useful and pleasing sci- ence. To obviate these inconveniences is the design of the author in the following pages ; whether he has suc- ceeded in his object, he leaves to a candid and impartial public to judge. With regard to imparting instruction, the author con- side rs the plan he has adopted in this work as preferable. From long experience as an instructor, he feels a confi- dence in recommending the interrogatory method, as at- tended with the greatest utility. Questions at the end of VI. rr.r.FAcr.. raclr chapter very much assist the learner ; and are like- wise convenient for the instructor. Each question hav- ing a reference to a particular section, the answer may be easily committed to memory ; by which means the remarks ©f the author are readily comprehended, and much time saved, which is too often employed in turning over the leaves of a book, searching for the object, with- out a suitable guide to direct to the place ; this has a tendency to discourage rather than promote exertion. No pretensions are made to originality in the follow- ing pages ; the work is a compilation. Neither is it de- signed to supersede any other. It is an introduction for the purpose of enabling students to commence with more pleasure and success those excellent works of Gorham, Thomson and Henry, which should follow this where a correct knowledge of the science is desirable. In this compilation, recourse has been had to the works cf va- rious chemical writers ; from which such extracts have been made as were thought necessary for an introduc- tion. If the subjects have been properly arranged, and treated in a clear and perspicuous manner, the author will be rewarded by a consideration that he has per- formed an important task ; but this he dares not flatter himself that he has been able, fully, to accomplish. Some, perhaps, may object that remarks have been made, and passages inserted, which will not be easily understood by beginners, particularly in the chapter on Chemical Equivalents and the Atomic Theory ; but the au- thor is not conscious of inserting any thing which is not admitted by the most eminent of the European chemists, and which he is confident is conformable to the most ac- curate and rigid experiments, as well as to just theory. In examining the remarks of authors on the above sub- ject, for the purpose of making a selection, being limited PREFACE. Vll- aS to the size of the work, he found that he must either omit the articles altogether, or treat them agreeably to the plan of the authors from whose works they have been extracted. The atomic theory has been adopted, under various modifications, by most scientific men of the present day ; and most treatises of chemistry that have been published within the last ten years have a refer- ence to it, especially in the proportions of the different compounds; the work, therefore, in his opinion, would have been very defective without some notice of the the- ory ; especially as one of the principal objects in the compilation was to prepare the pupil, by a knowledge of the first principles of the science, to enter upon fuller and more elaborate treatises, it became, therefore, ne- cessary to treat the subjects not only in a cencise man- ner, but conformably to the present exalted state of the science. Should any, however, be disposed to omit the chapter on chemical equivalents in the instruction of very young persons, it may be done without any derange- ment of the other parts. As some acquaintance with what is called Natural and Experimental Philosophy is necessary, previously to en- tering on the study of chemistry, the work is commenced with some of the rudiments of that science ; but brevity was absolutely necessary, as the limits assigned to the work would not admit otherwise. J. R. C. Boston, May 10th,. 1822. TABLE OF CONTENT*, 1. Definition—General laws of Matters-. Page 1 2. Of Elements or simple bodies—Chemical attraction or affinity. ... 9 3. Theory of Atoms—Definite propor- tions—Chemical Equivalents. - 21 1, Of Light—Caloric. - - - 38 Continuation of Caloric. - - B7 5. Of Combined Caloric. - - 69 6. Of Oxygen. ... 79 7. Of Azote orNitrogen. - - 80 8. Of Hydrogen. - - - 83 9. Of Sulphur. - - - 91 10. Of Phosphorus. - - - 97 11. Of Carbon. ... 103 12. Of Alkalies, - - - 111 13. Of the Decomposition of Alkalies and Earths. - - - - 123 14. On the Earths. - - - 133 15. Of Magnesia—Alumina—Yttria—Glu- cina—Zirconia—Silica and Thorina. 145 1G. Of the Acids. - - 157 17. Continuation of Acids. 166 18. Of Oxygen acids—Metallic. - 181 1.9. Of Hydrogen Acids. - - 1,86 20. Acids of organic origin. - - 192 81. Of Chlorine. - - 205 22. Of Iodine. - ... 213 83. Of Salts in general. - - 21G 21. Of Electricity—Voltaic Electricity. - 220 25. Of Metals. - - - 233 CO. Of Platinum—Gold—Silver—Palladium, Mercury. - - - 2 J 8 27. Of Copper—Iron—Tin—Lead—Nickel, Cadmium—Zinc. - - 251 28. Of Bismuth—Antimony—Manganese- Cobalt—Tellurium. - - 26C 20. Of Arsenic—Chromium, Molybdenum, Tungsten-—Cblumbiuui—Selenium— Osmium. ... 273 30. Ill; odium—Iridium—Uranium—Titani- um—Cerium—Wodanium. - - £8 J Ji. Of Prussine or Cyanogen.. - £G1 32. Of the nature and competition of Veg- etables. ..... 2C7 33. Of Colouring matter—D.composition of vegetables—Fermentation. - 30C 34. Continuation of Fermentation. - 210 35. Of Vegetation. ... 300 3Q. Of the animal deparlm.nt. - 343 37. Of Respiration. - 3(3j 38. On Animal Heat. - A Diet oaary of Chemical tcr.as. o i ABBREVIATIONS AND USED IN THE FOLLOWING WORK. ---—0^ A small (o,) placed at the right hand, over a figure, denotes degrees. F. at the right hand of a figure or figures, signifies Fa- renheit's thermometer. W. Wedgwood's pyrometer. It. Reaumer's thermometer, The sign -f- signifies that the figure to which it is pre- fixed is to be added. The sign — signifies that the figure which it precedes is to be subtracted. When prefixed to degrees of the thermometer, it signifies that the temperature is so many degrees below zero. The sign X signifies that the figures between which it stands are to be multiplied together. The sign 4- signifies that the figure preceding it is t« be divided by the figure which comes after it. The mark =, called the sign of equality, signifies that the amount of the figures preceding are equal to the succeding. :, ::. Signify that the figures between which they Stand are proportional. DIRECTIONS FOR THE BINDER. Plate 1. Table of Cher-' .ivalents, to face Title. 2. To face page - - .46 3. " - - . . . 84 4- ".....125 Table of Metals. Plate 5. - .... 3S ~O.J •JO AM INTRODUCTION TO CHEMISTRY. CHAPTER I. Definition, «^c.—General Laws of Matter. 1. Chemistry is the science which investigates the combinations of matter, and the agencies of those gener- al forces whence these combinations are established or subverted. 2. The subjects of Chemical inquiries are particles of matter, both the magnitude and form of which, and the distances within which they act upon each other, are wholly incapable on account of their extreme minute- ness to be estimated. Observation. Authors are not agreed with regard to the etymology of the word Chemistry ; it is generally thought to be of Arabian origin. 3. Matter is the first principle of all natural things, from the various combinations and arrangements of which all bodies are formed. 4. Substance is that which supports the different forms and appearances which are presented to our senses. In common language it means a distinct or definite por- tion of matter, whether solid or fluid Observation. The word substance is compounded of the Latin -preposition sub, under, and sto to stand; it differs from matter, because it implies a determinate fig- 1 I-M'KODC'CTrON ure, wheroa?, matter implies a more genernl and confus- ed idea of solidity and extension, without any regard to figure. 5. Every kind of substance has certain characteristic properties, such as Solidity, Divisibility, Mobility anil Inertia. 6. By solidity or impenetrability, in common language is to be understood the property of not being easily separated into parts. Observation. If a piece of wood or stone occupy a certain space, they must first be removed before another body can be put in the place ; and though fluids, from their nature, appear at first to oppose such resistance, yet in proper circumstances they will be found to retain the property in an equal degree. Exp. 1. Put some water into a tube closed at one end, and insert into it a piston, a piece of wood, or metal, which exactly fit the bore of the tube ; then try to push the piston to the bottom, you will find it impossible, even by the force of the greatest pressure. Exp. 2. Pour the water from the tube, which will be empty as it is called in common language, but in reality, filled with atmospheric air. In attempting to push the piston to the further end, you will meet with the .same resistance as before. 7. We derive our idea of impenetrability from the resistance which we meet with in bodies, whether they be solid or fluid. 8. Divisibility is that property by which matter is ca- pable of being divided into parts, and those parts separat- ed from each other. Observation. This divisibility is evident in bodies of sensible magnitudes ; we can never by subdividing arrive it a part so snail, but we can^conceive that it consists of TO CHEMISTRY". 3 (wo halves, but how far this actual division may be car- ried, whether to infinity or whether we should at last arrive at ultimate atoms, which from their nature, are not capable of subdivision, is a point not ascertained. The actual division of matter may be carried to an a- mazing extent,so as to approximate to our ideas of infinity. Illustration 1. A grain of gold is hammered by the gold beaters* until it is the thirty thousandth part of a line in thickness, and will cover fifty square inches.— Each square inch may be divided into two hundred strips, and each strip into two hundred parts, which may be seen with the naked eye ; consequently a square inch contains forty thousand visible parts, which multiplied by iifty, the number of square inches which a grain of gold will make, give two million parts, which may be seen with the naked eye. 2. It has been calculated that sixteen ounces of gold, which, in the form of a cube, would not measure one inch and a quarter in its side, will completely gild a quantity of silver wire sufficient to surround the globe. Exp. 1. Put into a quart of water a small piece of ni- trate of silver, lunar caustic, not larger than a common pin^ head, it will impart a uniform milky colour to the whole liquor. Exp. 2. Into a pint of water put a small piece of sul- phate of copper, blue vitriol, not more than the one hun- dredth of a grain, it will impart a sensible blue colour to the whole liquid. 9. Mobility is that property by which bodies are ca- pable of being moved, from one place to another. 10. Inertia is a tendency which bodies possess of con- tinuing in the state in which they are placed, whether of rest or motion, unless prevented by some external force. 4 INTRODUCTION Illustration 1. A man standing in a boat while it is push- ed from the shore, will be in danger of falling backwards, but he will gradually acquire the motion of the boat, anil if it be suddenly stopped, he will fall forwards, because his tendency will be to continue in motion. 2. A mm riding on full gallop, if the horse suddenly stop, is in danger of falling over the animal's head, his body having acquired the motion of the horse. 11. Space has no limits or bounds; it consists of part-1, which may be divided by the mind, but are not capable of actual separation. Its parts are only distinguished by bodies placed in them. 12. Space is either absolute or relative. 13. Absolute space is mere extension, it has no limits or bounds, and is itself immoveable. 14. Relative space is that part of absolute space that is occ ipied by any body, and is compared by any part oc- cupied by any other body. i.',. Motion is either absolute or relative. I''.. Absolute motion is the actual meUon which bodies pr ess, in:!ep»n Lint of each other, and only with regard to ii1. parts of space. 17. Relative motion is the degree and direction of the motion of one body compared with that of another. Illustration. By this .mperceptibie motion plants and animi'.s grow, and the greatest number of compositions and decompositions throughout the globe take place. Tiie t.;mperatfre of bodies is constantly varying, con- sequently the particles must be in continual motion, ia order to adapt themselves to the size of the body. 18. Accelerated motion is, when the velocity of mo- tion continually increases. 10. Retarded motion is, when the velocity continue ally decreases. TO CHEMISTRY. O 20. The velocity of uniform motion is estimated by the time employed in moving over a certain space, or by the space moved over in a certain time. 21. To ascertain the velocity, divide the space run over by the time. 22. To know the space run over, multiply the* ve- locity by the time. 23. In accelerated motion, the space run over is as the square of the time, instead of being directly as the time, as in uniform motion. Illustration. A body falling from a height, moves at the rate of 16 1-12 feet in a second of time, and acquires a velocity of twice that, or 32 1-6 in a second. At the end of the next second it will have fallen 64 1-3 feet.— The space being as the square of the times, the square of 2 is 4,-and 4 times 16 1-12 is 64 1-3. And so on. 24. By velocity is meant what bodies would acquire if they should fall through a space where there was no air. Its resistance diminishes considerably their velocity in falling. Therefore in estimating the velocity of bodies, this circumstance must be taken into consideration. 25. A body acted upon by one force will always move in a straight line. 26. Bodies acted upon by two uniform forces, wheth- er equal or unequal, must form a straight line. But if one of the forces be not uniform, that is, either accelerating or retarding, the moving bodies will describe a curve line. Illustration. If a ball be projected from a cannon, it receives an impulse, which, if there were no resistance from the air, and if it were not acted upon by gravity, would cause it to move always ,n a straight line, but as «oon as it leaves the mouth of the cannon, gravity acts upon it, and causes it to change its direction to that of a curve. i* O INTRODUCTION 27. The momentum of a body is the force with which it moves, and is in proportion to the weight or quantity of matter, multiplied into its velocity. 28. All bodies appear to possess attraction and repul- sion, the causes of which are totally unknown. 39. There are various kinds of attraction, viz. the at- traction of cohesion; of gravitation ; electricity; mag- netism ; and chemical attraction or affinity. 30. All the phenomena of chemistry arise from the attractions and repulsions exerted between the particles of matter. 31. Attraction of cohesion acts only at very small dis- tances. It is by this attraction that bodies preserve their forms, and are prevented from falling to pieces. Exp. 1. If two leaden bullets have a little scraped from each, so as to make them fit exactly in those parts, and they be put together with a twist, they will adhere so strongly as to require a considerable force to separate them. Illustration. Hardness, softness, brittleness, ductility and malleability depend upon different modifications of the attraction of cohesion. 32. When a body is in solution, and the attraction of cohesion is exerted suddenly, the particles unite indis- criminately and form irregular masses. But when it acts more slowly, the particles assume a particular arrange- ment, and form masses of regular figures. This is term- ed crystallization, and the regular figured masses are de- nominated crystals. 33. Attraction of cohesion is the cause of the forms in which different bodies exist, and the regular figures which many of them assume. 34. The attraction of gravitation or gravity is the tendency of bodies towards each other, which is exerted at all distances. TO CHEMISTRY. 7 35. Every particle of matter in the universe gravi- tates towards every other particle. Illustration 1. By the attraction of gravitation, the heavenly bodies are retained in their orbits by their mu- tual action ; and by this, a stone dropped from a height falls to the surface of the earth. 2. The planets and comets all gravitate towards the sun and towards each other as well as the sun toAvards them, and that in proportion to the quantity of matter in each. 36. All terrestrial bodies tend towards a point, which is exactly or very nearly the centre of the earth, conse- quently bodies fall every where perpendicular to the surface, and on opposite sides in opposite directions. Observation. If two bodies of equal quantity of mat- ter were placed at ever so great a distance from one another, and left at liberty in free space, and if there were no other bodies in the universe to affect them, they would fall equally swift towards one another, and would meet in a point which was half way between them at. first. 37. Gravitation decreases from the surface of the earth upwards as the square of the distance increases. 38. We know nothing of gravity but by its effects. 39. Electric attraction is that exerted by amber, seal- ing wax, and some Other substances when rubbed. Illustration. When amber and sealing wax are rubbed with a silk handkerchief, they attract feathers, dust, &c. from small distances. 40. Magnetic attraction is that exerted by the load- stone on iron. Illustration. The tendency of the needle to the pole is an instance of this attraction. i Introduction PRACTICAL QUESTIONS. What is Chemistry ? What are the subjects of Chemical inquiries ? •What is matter ? What is substance ? What are the characteristic properties of matter ? What is understood by solidity ? Do fluids possess solidity ? Illustrate this by experiment. How do we obtain our ideas of impenetrability ? What is divisibility ? Illustrate this. What experiment can you exhibit to confirm it. What is mobility ? What is inertia ? Illustrate it. What is space ? How is space divided ? What is absolute space ? What is relative space ? How many kinds of motion are there 'I What is absolute motion ' What is relative motion ? Illustrate it. What is accelerated motion ? What is retarded motion 1 How do you estimate the velocity of retarded motion t How do you estimate the space run over ? How is the space in accelerated motion ? Illustrate this. What is meant by velocity ? How will a body move that is acted upon by one force ? How if acted upon by two forces ? Illustrate it. TO CHEMISTRY. 9 What is the momentum of a body 1 What do all bodies appear to possess 1 How many kinds of attraction are there 1 From what do all the phenomena of Chemistry arise ? What is attraction of cohesion ? Illustrate this. What is the effect when the attraction of cohesion is exerted suddenly. What is the cause of the forms of different bodies ? What is the attraction of gravitation 1 How does every particle of matter gravitate ? How is it with regard to the planets and comets ?. How with regard to terrestrial bodies ? What would be the consequence suppose there were only two bodies in the universe, and they placed at a distance from each other ? How does gravitation decrease from the surface of the earth ? What do we know of gravity f What is electric attraction ? Illustrate it. What is magnetic attraction ? Illustrate it. CHAPTER II. Of elements or simple bodies—Chemical attraction or affinity. 1. In a Chemical sense, substances are divided into two kinds, vz. simple and compound, the former of frhich are sometimes called elements. 10 INTRODUCTION 2. Simple bodies are those which have not been sep- arated into others more simple, nor reproduced by arti- ficial means. Observation 1. The ancients considered four substances as simple and uncompounded, which they denominated elements, viz. earth, air, fire and water. These have all been decomposed, and their constituent parts well as- certained. Observation 2. It would perhaps be presumption to as- sert that we are acquainted with any simple body. Those which we now call elementary may hereafter be found to be compounded. Many that were supposed to be sim- ple twenty years ago have been decomposed, and their component parts clearly exhibited to the senses ; such are earths and alkalies. 3. The term, elements, should be considered as denot- ing the last term of the analysis, according to the present state of knowledge. 4. The number of simple substances is constantly changing, as new discoveries are made. Those which rank under that term, at present, are fifty. 5. Excepting the more general agents of nature, heat, light, and electricity, it is thought by some, that the sim- ple bodies may ultimately be resolved into metallic sub- stances, but this is doubted by others ; and no experi- ment on any one of the simple substances, tends to con- firm the hypothesis. 6. The simple substances are at present divided into two classes; the one called combustible or inflammable ; and the others, supporters of combustion, because in combining with the first class, much light and heat are developed. 7. Should the experiments of the French chemists prove correct, with regard to some of the newly discov- TO CHLMISTRV. 11 ered substances, the present division between the com- bustible bodies and those which support combustion, will hardly be warranted. C. Some of those which support combustion, appear to act the part of both, combustibles and*supporters. Illustration. Sulphur gives light and heat to a certain extent, in its combination with some of the metals, and also when it combines with oxygen, with which as an in- flammable body it forms an acid. In the opposite char- acters, like chlorine and iodine, it forms an acid with hydrogen, which is termed the hydrosulphuric acid. 9. Some suppose that phosphorus, carbon and azote, have a property similar to that of sulphur. 10. Most of the simple combustibles have been prov- ed to be metals, and hydrogen is believed by some to be a metal in an elastic form. 11. Those bodies whose metallic natures have not yet been fully ascertained, appear to possess the property of combining more strongly with inflammable bodies, than the metals with each other in forming alloys. 12. The combinations of metals w.th those that are not metallic,are generally conspicuous and always definite. 13. All the simple substances combine and form com- pounds, and from these, combined in different ways, an indefinite number of substances are pro-luc^d. 14. Chemical attraction, or the attraction of compo- sition, commonly called Chemical affinity, is a tendency which bodies of a different nature have to unite with one another, and form substances which are different from the bodies that have been combined. 15. The attraction of aggregation is that which takes place between parts of the same substance, or between bodies of the same kind, and difiers not materially from the attraction of cohesion. 12 INTRODUCTION 16. An aggregate is a coherent body, and must be distinguished from a heap, for though a heap consists of parts all of a similar nature, yet those parts have no co- hesion with each other. Illustration. A ma^s of rock is an aggregate, where particles cohere, but a mass of sand is a heap, being com- posed of distinct and separate particles. 17. A mixture is a mass of substances of a different nature. Illustration. Gunpowder composed of charcoal, sul- phur and nitre. 18. There are several kinds of aggregation, as 1. The solid, as wood, metal, sulphur 2. The soft, as in glue, meat, jellies. 3. The h pid, as in water and oil. 4. Aerifon.i, as in air and vapour. Illustration. W.xx and tallow, when in a temperature of 50° are solid, at 80° soft, at 160° fluid, and between 300 and 400° vapounzed or aeriform. 19. Every effort that tends to separate the particles of bodies, tends to destroy the attraction of aggregation. In all cases the force applied, must be more than equal to the force of attraction. Illustration. Grinding, cutting, pounding, &c. 20. If the aggregation of a body be diminished, it ex- hibits a greater surface. Illustration. A lump of sugar or salt when broken into bits, will present a larger surface than when whole. Observation. By this means the energy of chemical agents is increased ; thus fluate of lime, (Derbyshire spar) is scarcely affected by sulphuric acid in the lump ; but let it be first ground into powder, and a rapid decom- position takes place ; the fluoric acid is disengaged in the iorm of gas, it being compounded of this add and hme ; in the decomposition, the sulphuric acid combines with the lime, forming what is called sulphate of lime. TO CHEMISTRY. ] J 21. The force of this attraction is estimated by the power required to overcome it. Illustration. Hence arises the difficulty of cutting mar- ble, flint, and the diamond ; hence also the different de- grees of exertion required to separate the several kinds of timber. 22. Different degrees of heat are required to over- come the several kinds of aggregation. 23. Hot liquids not only dissolve substances quicker, but in much larger quantities ; when, however, the liquor cools, part of the substance falls to the bottom of the ves- sel, in regular crystals. Exp. Take an ounce of glauber's salt, sulphate of so- da, which has been dried over the fire and become a white powder, dissolve it in two ounces of boiling water; when cold, the original crystals will be seen in the fluid, notwithstanding the salt was reduced to powder. 24. Chemical attraction differs from the attraction of aggregation in this ; the former unites bodies of different natures, while the latter only those of the same. Illustration. Sand and alkali exposed to a strong heat, combine and form a substance called glass. In this state it is a uniform whole, which no mechanical efforts can again separate into sand and alkali, and the properties of glass are not only different from those of sand and salt, but in many respects quite contrary. It is transparent and insipid. Exp. 1. Put a small quantity of mercury and sulphur into a crucible, an ounce of each, and stir them together over a fire, till the sulphur is completely melted, then pour the mixture on a piece of glass or marble, previ- ously greased or warmed. The substance obtained from this composition, is sulphuret of mercury, and has neither colour, brilliancy, inflammability, nor volatility of either 2 14 INTRODUCTION of its component parts. Neither can the ingredients, be separated from each other by any mechanical means. 2. Dissolve mercury in nitric acid, for which it has a strong affinity, to the point of saturation, that is, when it will dissolve no more, every particle of acid has at- tracted a particle of mercury. The liquid has lost its acid taste, and acquired that of a metallic one, if it be slowly evaporated, a salt will be formed, which in its properties and appearance is entirely different from its ingredients. 3. The burning acid nature of quicklime and sulphu- ric acid is well known ; if we mix a small quantity of .oach together, the corrosive nature of both is destroyed, and the substance produced from this union is called Plaster of Paris, or gypsum ; in chemical language, it is sulphate of lyne. 4. A spoon-full of salt thrown into water and dissolv- ed, diffuses itself through the whole of the fluid, and the suit is said to be combined with the water; the water and the salt have a certain affinity for each other, they eannot be separated by any mechanical means ; but if another substance be added io which water has a great- er affinity than it has to the salt, it will quit the salt to unite with this third substance. If therefore alcohol be added, the water will leave the salt to join the spirit ; and the salt, by its superior gravity, will fall to the bot- tom of the vessel. 5. Dissolve camphor in alcohol, the solutien is per- fectly clear, which is another instance of chemical affini- ty ; but the spirit has a stronger affinity for water than for camphor, and if a little of that be added, the camphor will fall down in white flakes, or in a solid form. 6. Put some acetate of soda into a retort, add muriatic acid and distil the mixture to dryness; the fire will drive TO CHEMISTRY. 15 off the acetic acid, but will have no effect on the muri- atic acid, while in combination with the soda, which proves that the soda has a greater affinity for the muri- atic acid than for the acetic. If now nitric acid be added to the muriate of soda, and heat applied, the muriatic acid will be driven off, the nitric acid is combined chem- ically with the soda, and the substance is a nitrate of soda; to which, if sulphuric acid be added, and heat applied, the nitric acid will be expelled, and the sulphu- ric acid will unite with the soda, forming a true sulphate of soda. These changes take place in consequence of chemical affinity. 25. Decomposition and division are very different in their operations; the latter simply reduces a body into parts, while the former separates the various ingredients' of which it is composed. Illustration. When we break with a hammer a piece of marble, we merely divide it, each part still retaining air its constituents, and this may be done without any knowledge of chemistry,~ but when-the chemist attempts to analyze it, he finds-it composed of carbonic acid an.l lime, for this purpose he appliesa third substance which has a greater affinity for lime than the carbonic acid ha?, by this means he separates the constituents, this is called decomposition. 26. When we decompose a substance, we resolve it into its constituent parts ; when we divide it, into inte- grant parts ; hence the difference between elementary and integrant particles. 27. Bodies are decomposed by chemical attraction, by adding a third substance which has a greater affinity for one of its constituents than the other, in this way it unites with one, and the other is set at liberty. 16 INTRODUCTION Illustration. This may be illustrated by three letters. A. B. C. Let the two ingredients be A and B ; present to this compound the third ingredient C. which has a greater affinity for B. than that which unites A and B. it follows that B. will quit A. to unite with C.; therefore C. has effected a decomposition of A. B. A. has been dismissed, and B. and C. form an union. Exp. Dissolve some nitrate of copper in water, and immerse in it a piece of clean bright iron. A decompo- sition takes place, the nitric acid having a stronger affin- ity for the iron than it has for the copper, attacks the iron and setting at liberty the copper, it is precipitated in its metallic form. 28. Chem'sts have established certain principles cal- led Laws of affinity. The first is, that it acts only in the union of bodies of different natures, and forms a third substance totally different from either of the constitu- ents. Illustration. Sulphuric acid and soda when combined, iorm glauber's salt, or sulphate of soda. Second. Chemical affinity acts only between the mi- nute particles of bodies. Exp. A lump of sulphur thrown into alcohol, will cause no action ; but if the sulphur be minutely divided, the bodies will unite, and the solution be perfectly trans- parent. The union is thus effected ; put some pounded sulphur into a cucurbit A. Plate 2, fig. 2, suspend within it a phial B. containing alcohol; and when the whole is covered with the head C. and the joinings well luted, heat the apparatus by means of the lamp F. The sul- phur will soon rise up in small particles, and will unite with the particles of alcohol which will likewise be driv- en off by the heat, and will be collected in the matrass'X. To prove that the sulphur has united with the alcohol. TO CHEMISTRY. 17 add some distilled water for which the alcohol has a stronger affinity than for the sulphur, the latter will be precipitated. Third. Attraction may take place botween several bodies ; thus two, three, or more metals may be fused together, so as to produce compounds, the properties of which are very different from those of the constituent parts. Exp. Melt eight parts of bismuth, five of lead, and three of tin together, and when united, the compound is so fusible, that a spoon made of it will melt in boiling water. This property none of the metals possess sepa- rately. A composition of equal parts of lead, zinc and bismuth is so fusible, that it may be kept in fusion on a paper held over the flame of a candle. Fourth. Bodies will not unite chemically, unless one of them, at least, be in a fluid or aeriform state. Illustration. Neither sugar nor salt will combine with ice ; but they both unite with water. Fifth. When two or more bodies unite by affinity, their temperature suffers a change at the instant of union. Exp. 1. In a wine glass half filled with cold water, pour some sulphuric acid very gradually, a heat will be immediately perceived, which by the addition of the acid may be increased above that of boiling water. • 2. Hold in one hand a phial containing some pulver- ized muriate of ammonia, sal ammoniac, upon which pour cold water, and shake the mixture, a sensation of great cold will be immediately produced. Sixth. By chemical affinity some bodies acquire prop- erties very different from those which the compounding bodies had previously. Illustration; Iron and tin when combined by fusion, lose the property of malleability and ductility. 18 INTRODUCTION Exp. Drop concentrated sulphuric acid gradually into a saturated solution of muriate of lime, a solid will be formed from the two fluids. Seventh. The action of two compound substances, by which they mutually decompose each other, and produce two or more new substances, is called compound affinity. Exp. 1. If to a solution of sulphate of ammonia, there be poured nitric acid, no action takes place, because the sulphuric acid has a greater affinity for ammonia than nitric acid. But if instead of nitric acid, a solution of nitrate of potash be poured in, a double decomposition takes place, and by evaporation, two new bodies are ob- t lined, a sulphate of potash and nitrate of ammonia. In (iiis case, the sulphuric acid of the sulphate leaves the ammonia to unite with the potash ; and the nitric acid is disengaged and unites with the ammonia. /Exp. 2. If the sulphate of aluaiini be mixed with the acetate of lead in solution, a mutual decomposition tikes place ; the acetic acid of the acetate unites with the alumina, and the sulphuric acid with the lead. 29. The cause of chemical affinity or attraction of composition has net been fully ascertained. Observation. In 1803, Berzelius and Hisinger discov" ered the law respecting the agency of the galvanic bat- tery in the decomposition of bodies, viz. "That oxygen and acids are accumulated round the positive pole; while hydrogen, alkalies, earths and metals, are accu- mulated round the negative pole." From this general law Berzelius deduced the consequence, that the decom- positions in such instances were owing to the attractions subsisting between the bodies and the respective elec- tricities. This opinion was extended by Sir II. Davy, with which Berzelius afterwards coincided According to these celebrated chemists, chemical affinity is identi- TO CHEMISTRY. 19 cal with electrical attraction, and bodies which unite chemically, possess different kinds of electrical attractions. Every body, in their opinion, possesses a permanent elec- tric state, either resinous or vitreous. Two bodies in the same state of electricity have no affinity for each other, consequently, the attraction of cohesion which takes place between substances of the same nature, cannot be the same as electric attraction. According to the above theory, bodies in opposite states have an affinity, and the strength of this affinity is in proportion to the degree of intensity of the different electricities in the two bodies; in order to make bodies separate from each other, we have only to bring them into the same electric state by making them both vitre- ous or both resinous. It remains for future discoveries to ascertain whether this hypothesis be founded in truth; but there can be no question that electricity has great influence in the combination of bodies. We shall consider this subject further, under the arti- cle, electricity and galvanism. PRACTICAL QUESTIONS. How are substances divided in chemistry 1 What are simple bodies ? How did the ancients consider this subject ? How should the term elements be considered 1 What are the number of simple substances ? Into what may the simple bodies be resolved ? Enumerate them. Into how many classes are these substances divided ? But may not this division be incorrect ? Do any substances act the part of combustibles and supporters ? Illustrate this. 20 INTRODUCTION What is thoHght of carbon, phosphorus and azote ? What is carbon and azote believed to be ? What has been proved with regard to the simple com- bustibles ? What do those bodies which have not been proved me- talic, appear to possess 1 How is the combination of metalic with non-metalic substances ? How is the combination of simple substances? What is chemical attraction 1 What is the attraction of aggregation ? How does an aggregate differ from a heap ? Illustrate this. What is a mixture ?'. Illustrate it. How many kinds of aggregation are there ? Illustrate it. How is the attraction of aggregation destroyed ? If the aggregation of a body be diminished, what does rt exhibit ? How do you illustrate this ? How do you estimate the force of this attraction ? What is required to overcome the different kinds of aggregation ? What effect have hot liquors to dissolve substances 1 How does chemical attraction differ from aggrega-. tion? Illustrate it. What is the difference between decomposition and di- vision ? Illustrate it. What do we, when we decompose a substance ? How are bodies decomposed 1 Illustrate it. TO CHEMISTRY, 21 What have been established by chemists with regard to attraction ? What is the first law ? Illustrate it. What is the second law ? Illustrate it by experiment. What is the third law ? How would you illustrate it ? What is the fourth law ? Illustrate it. What is the fifth law ? Illustrate it by experiment. What is the sixth law ? Illustrate it. What is the seventh law ? Illustrate it by an experiment. What is the cause of chemical attraction ? What observations have you to make on this subject? CHAP. III. 'Vfieory of Atoms,—Definite proportions—Chemical Equiv- alents, fyc. 1. The atomic theory is the manner of explaining the compos:tioa and decomposition of bodies by consid- ering their ultimate atoms or particles as peculiar and dis- tinct elementary solids, never changing in their figure, weight, or volume, and utterly incapable of being di- vided. 2. By means of this theory which is now generally admitted under certain modifications, by the most scien- 22 INTRODUCTION tific Chemists, Chemjstry has been elevated to the rank of a mathematical science, and made to occupy one of the most distinguished places in the field of philosophical research. 3. Sir Isaac Newton seems to have had an idea of the theory of atoms, or ultimate particles, by the following sen- tence. After speaking of the laws of chemical attraction, he proceeds as follows. "All these things being considered,. it seems probable to me that God in the beginning formed matter in solid, massy, hard, impenetrable, immoveable particles, of such sizes and figures, and in such propor- tions to space, as most conduced to the end for which he formed them; and these primitive particles being solids, are incomparably harder than any porous bodies com- pounded of them ; even so very hard as never to wear or break in pieces ; no ordinary power being able to divide what God himself made one in the first creation. While the particles continue entire, they may compose bodies of one and the same nature and texture in all ages ; but should they wear away, or break in pieces, the nature of things depending upon them would be changed. Water and earth composed of worn out particles, and fragments of particles would not be of the same nature and texture, now, with water composed of entire particles in the beginning. And therefore, that nature may be lasting, the changes of corporeal things are to be placed only in the various separations and new associations and motions of these permanent particles, compound bodies being apt to break, not in the midst of solid particles, but where those particles are laid together, and only touch in a few points." 4. Mathematicians conceived matter to be infinitely divisible, but, in nature its divisibility was thought to be limited to the hard and impenetrable atoms TO- CHEMISTRY 23 5. The idea of atoms appears to have-been>first pro- mulgated in any chemical work in L790, by Mr Higgins, and by J. B. Richter, of Berlin, in 1792. Very little notice was taken of the subject by chemists until Mr. John Dalton of Manchester, Eng. published his system-of definite pro- portions, since which it has received additional support and improvements by the most celebrated chemists in different parts of Europe. 6. The French chemists have adapted the atomic the- ory under another form, whjch agrees with the lan- guage given by Berzelius, viz that of volume. 7. Dr. Wollaston introduced into the science, the term chemical equivalents, to express the different rat.os in which the corpuscular subjects of this science reciprocal- ly combine, referred to a common standard which is reckoned unity.—Plate 1. 7. He assumed oxygen as a standard, from its being almost universally combined in chemical matter. 8. If-oxygen be made unit}', we shall have in the fol- lowing table, their ratios reduced to.their lowest terms in which the equivalents will be prime ratios or pro- portions. The lowest ratio, or equivalent prime of being 1,000 of hydrogen will be 0,125 Offluor? - 0,375 Of carbon, - - 0,750 Of phosphorus, >- 1,500 Of azote, - - 1,750 Of Sulphur, 2,000 Of calcium, - - 2,550 Of sodium, - - 2,950 Of potassium, - - 4,950 Of copper, - - - - 8,00 24 INTRODUCTION Of barium, ... - 8,75 Of lead,.....13,00 &c. i). The substances in the above table, susceptible of reciprocal saturation, can combine with oxygen, or with each other, not only in proportions corresponding with these numbers, but frequently in multiple or submultiple proportions, as in 1 and 1 : 1 and 2, &c. from this have been adduced two general proportions of vast importance to the science—viz. 1st. The mutual action ofthe sat- urating porportions.—2d, The multiple and submultiple proportions of prime equivalents in which any one body may unite with any other body to constitute successive binary compounds. 10. The first of these laws was inferred from the re- markable and well established fact, that two neutral salts in decomposing each other, produce two new saline com- pounds perfectly neutral. Illustration.—Sulphate of soda being added to muriate of lime will produce perfectly neutral sulphate of lime and muriate of soda. 11. Richter drew the following conclusion.—1st, That the quantity of two alkaline bases, sufficient to neutralize equal weights of any one acid, are proportionable to the quantities of the same bases sufficient to neutralize the same weights of every other acid. Illustration.—Six parts of potash or 6 of soda, will neu- tralize 5 of sulphuric acid, and 4.4 of potash will saturate 5 of nitric acid. Therefore to find the quantity of soda equivalent to the saturation of this quantity of nitric acid, it may be computed by the proportional rule of Richter without having recourse to experiment, in the following manner, as 6 : 4.4: : 4: 2.93 ; that is, as the potash equiv- alent to the sulphuric acid, is to the potash equivalent to the nitric acid, so is the soda equivalent to the first, to the soda equivalent to the second. TO CHEMISTRY. 2. 6.5 potash, saturate 5 of muriatic acid gas, what pro- portion of soda by Richter's rule, will be required to pro- duce the same effect ? We say 6 : 6.5: : 4 : 4.3. 3. If 10.9 potash combine with 5 of carbonic acid how much will be equivalent to that effect. Now, 6. 10.9 : : 4 : 7.26. Here we have found, that if 6 potash be equivalent to 4 soda, in saturating 5 of sulphuric acid, this ratio of 6 to 4, or 5 to 2, will pervade all the saline combinations ; so that whatever be the ouantity of pot ash requisite to saturate 5, 10, &c. of any other acid, two thirds of that quantity of soda will suffice. 4. In the same manner let us find out for five of sul phuncacid,orofany one standard acid, the saturating quantity of ammonia, magnesia, lime, sti-ontites, barvtes peroxide of copper, and the other bases; then their pro' portions to potash, thus ascertained, for this acid, will bv arithmetical calculation, give their Saturating quantitvof every other acid, whose relation to potash, or any other of these bases is known, 12", £h! Ve'ification of the ab°ve important law oc- cupied Richter from the year 1791, to 1802 With in defatigable zeal he examined each acid in its relation to the bases, and then compared the results with those ffiv en by calculation, which he arranged in an extensive se" ries of tables. But all his tables have since been reduced into a single one, of 21 numbers, divided into two col umns,by means of which, every question relating to the included articles might be solved by the rule of three or a sliding scale.—Plate .1. The following table was composed from Richter's last tables. S 26 Bases. Oxygen = 1. ' Acids. Ox'gen=l Alumina, 525 2.625 Fluoric, ■121 7.135 Magnesia, 615 3.075 Carbonic, 577 2.885 Ammonia, 672 3.36 Sebacic, 706 3.530 Lime, 793 3.965 Muriatic, 712 3.560 Soda, 859 4.245 Oxalic, 755 L>.775 Strontian, 1229 6.645 Phosphoric , 679 4.895 Potash, 1605 8.025 Formic, 988 4.94 Barytes, 2222 1.111 Sulphuric, 1000 5.000 Succinic, 1209 6.045 Nitric, 1405 7.025 1 Acetic, 1480 7.400 Citric, 1483 8.415 1 Tartarous. 1694 8.470 The object of the above table was to give directly the quantities of acid an d alkali requisite for mutual satura- tion. For example, 1605 opposite to potash is the quan- tity of that alkalic equivalent to neutralize 42.7 fluoric acid 527 carbonic, 712 muriatic, 100 sulphuric, &c. Each column affords also progressive increasing numbers. Those nearest the top have the greatest acid or alkaline energies as measured by their powers of saturation. Hence the first columns, give, as far as analysis would jus- tify, in the time of Richter, a table of the relative weights of atoms. 14. Two chemical constituents frequently unite in different proportions, forming distinct and often dissimilar compounds. Illustration. Oxygen and nitrogen unite and constitute in one proportion nitrous oxide ; in a second proportion nitric oxide. In a third nitrous acid, and in a fourth nitric acid. The law by which these various compounds are regulated, is the doctrine of definite proportions. i 3. By this law bodies are supposed to be composed ■■?f T.r.hr/'.'ve ate m?, which combine with each other to form TQ. CHEMISTRY. 27 the different compounds. These atoms are supposed to be spherical, and can only combine 1 atom to 1, 1 to 2, 1 to 3, and so on. The number of the atoms of one ele- ment being some multiple to the atoms of the other. 16. Hence it follows thathodies unite together in cer- tain definite proportions by weight, that certain weights of some bodies combine with certain weights of other bodies. 17. Substances in a gaseous state have been demon- strated to combine with reference to their bulk or volume, that is, one volume of one gas always combines with on-* or more similar volumes of another, and not with any odd fractional parts. The volume or bulk of the resulting compound, if it happens to be gas, always bears a simile" relation to the original volumes of its component gases. 18. The same weights of the same resulting com- pounds are formed when bodies unite in a gaseous state according to their volume, as when they unite in any oth- er manner according, to their weight. Illustration. 1 volume, (say 100 cubic inches) of muri- atic gas will unite with 1 volume, 100 cubic inches of am- moniacal gas, and form the same weight of the same com- pound, viz. muriate of ammonia, as if 39,183 grains, the absolute weight of 100 cubic inches, of muriatie acid, unit- ed with 18.003 grains ; the absolute weight of 100 cubic inches of ammonia; the two numbers 39.183 and 18.003 being to one another as 1.273 : 5900, or as 37: 17. The specific gravities and the weights of these two substances respectively. 19. If the hypothesis and data are correct, it follows that the weights of the atoms of bodies are to one anoth- er as the specific gravities of the same bodies in a state of ga<*. ?0 If hydrogen be taken as unity, as is the case in 28 INTRODUCTION Dalton's experiments, then the weights of the atoms of all bodies will be multiples of this unit:. this is verified partly by experiment, and partly by hypothesis. 21. The above opinion has been formed upon the fol- lowing grounds.—1st, The specific gravity of ammo- niacal gas, according to Sir H. Davy, is 590164, common air being 1,000. According to Riot and Arrago it is a frac- tion greater; hence Dr. Prout infers it to be 5902 as the specific gravity of this gas. The specific gravity of ni- trogen, he assumes as 9722, common air being 1,000. Now as ammonia is known to be composed of one volume nitrogen and three volumes.hydrogen, condensed into two volumes, the specific gravity of hydrogen, according to these data must be 0694. 22. Atmospheric air is admitted to be universally composed of about 21 per cent of oxygen, and 79 per cent of nitrogen, which so nearly corresponds with one volume of oxygen, and four volumes of nitrogen, or 20 of the former to 80 of the latter, that it is inferred to be its true composition. Now the weight of the atom of oxygen being supposed to be so, and that of the atom nitrogen 17.5 the specific gravity of oxygen gas, accordingly, will be 1.1111 and that of nitrogen 9722. These numbers are multiples of 0694, for 1. 1111, divided by 0694=16 and 9722 divided by 0694=14. 23. There are some substances whose specific grav- ities do not correspond with the weight of their atoms. Thus the specific gravity of oxygen is 16 times that of hydrogen, while the weight of its atom, or its combining weight is only half or eight times that of hydrogen, but the specific gravities are always some multiples of the weight of the atom. 21. When the specific gravity is double the weight of the atom, as that of oxygen, we must suppose that the TO CHEMISTRY. 29 particles :.re».ncarer each other in the proportion of 2 to 1, or that two particles come together, and are surround- ed by the caloric which belongs to one of them in the:r single state. 25. It appears that the oxjgen puts on this single slate of existence in the formation of carbonic oxide, because that gaseous body contains only 1 atom of oxygen; hence its specific gravity is the same es if formed from a gas- eous oxygen of half the real specific gravity united to an at- om of carbon without any change of volume, the same as takes place when sulphur or carbon is burnt in oxygen gas. Hence the great tendenc}r which oxygen possesses of combining in double doses with bodies, as is the case with carbon, sulphur, phosphorus, iron and many others. 23. We have al^o an instance of a compound gaseous body becoming double the specific gravity which would be expected, in ole'fiant gas, which is composed of 1 atom carben and 1 atom hydrogen. The specific gravity, hydrogen being 1, ought to be 1X5.1=6.4: whereas, in fact, it is about double of this. Hence we should con- clude that the repulsion between the particles is halved, or that the compound atoms have united in pairs by which the density is doubled. 2T. The quantity of acid, according to Gay Lussac, which the different metallic oxides require for saturation, is in direct ratio to the quantity of oxygen which they res- pectively contain. This principle was discovered by observing tbe mutual precipitation of the metals, from their solution in acids. Experiment. 1. When we precipitate a solution of a- cetate of lead by a plate of zinc, a beautiful vegetation is formed, known under the name of the tree of Saturn and which arises from the reduction of the lead by a galvanic process. At the same time we obtain a solution 30 tUtRODUC1 ION of acetate of zinc equally neutral with that of the lead, and entirely exempt from it. Very little if any hydrogen is disengaged during the precipitation, which proves that the whole quantity of oxygen necessary for the solution of the zinc and saturation of the acid, has been furnished to it by the lead. 2. If we put into a solution of sulphate of copper, slightly acidulous, bright iron turnings in excess, the cop- per is almost instantly precipitated ; the temperature ris- es and no gas is disengaged. The sulphate of iron which we obtain is that in which the oxide is at a minimum, and the acidity is exactly the same as that of the sulphate of ropper employed. 3. Similar results may be obtained by decomposing •he acetate of copper by lead, particularly by the aid of heat. But since the zinc precipitates the lead from its acetic solution, we may conclude that it woald also pre- cipitate copper, from its combination with acetic acid. 4. Copper precipitates with facility silver, from its nitric solution. All the oxygen necessary for its solution i> furnished to it by the oxide of silver, for no gas is dis- engaged, and the acidity is not changed. 5. The same thing happens with copper in regard to nitrate of mercury ; and to cobalt with respect to silver. In these examples, as well as the preceeding, the precip- itat:ng metal is furnished with all the requisite oxygen from the metal, while it precipitates, all that is necessary for its oxidizement and for neutralizing- to the same degree the acid of the solution. 28. M. Gay Lussac has shewn with regard to the same •etals, at their different states of oxidizement, that they require of acid a quantity precisely proportional to the wuxntity of oxygen they may contain, or that the acids in the salts a.e exactly proportional to theoxygen in the ox- TO CHEMISTRY 3 f ides. This law affords a ready way of determining the proportions of all the metallic salts. The proportions of one metallic salt, and the oxidation of the metals being given, we may determine those of all the salts of the same genus, or the proportions of acid and of oxide of all the metallic salts ; and the oxidation of a single metal being given, we can calculate the oxidation of all the rest, since the peroxides require the most acid, we can easily understand how the salts containing them should, in gen- eral, be more soluble than those with the protoxide. 29. Berzelius, a Swedish chemist, contributed es- sentially to the science of chemical ratios. He assumed oxygen as the unit of proportion. 30. Dr. Wollaston's scale of chemical equivalents, Plate 1, fig. 1, has contributed more to facilitate the general study and practice of chemistry, than any other invention. 31. Dr. Wollaston discovered a series of numbers de- noting the relative primary proportions or weights of the atoms of the principal chemical bodies, both simple and compound. These were determined from a general view of the most exact analysis of other chemists as well as his own. 32. The list of substances which Dr. Wollaston has estimated, are arranged on one or other side of a scale of numbers, in the order of their relative weights, and at such distances from each other, according to their weights, that a series of numbers placed on a sliding scale, can at pleasure be moved, so that any number expressing the weight of a compound, may be brought to correspond with the weight of that compound in the adjacent column. The arrangement is such, that the weight of any ingre- dient in its composition, of any reagent to be employed, or precipitate that might be obtained in its analysis, may be found opposite the point at which the respective name is placed. 31 INiROIrtTCTIoN 33. If the slider be drawn upwards until it corres- ponds with the muriate of soda, the scale will then show how much of each substance contained in the table.is equivalent to two of common salts; viz. 26,8 dry muriatic acid, and 53.1 of sod;', or 39.8' sodium, and 13.6 oxygen ; or if viewed as chloride of sodium it contains 60.2, chlo- rine, and 39.8 sodium. With respect to seagents, it may be seen that 389 nitrate of lead containing 191 of litharge employed to separate the m-iriatic acid, would yield a precipitate of 237 muriat2 of lead, and that there would then remain in solution nearly 146 of nitrate of soda. It may at the same time be seen that the acid in this quan- tity of salt, would serve to make 232 corrosive sub limate, containing 185.5 red oxide of mercury, or make 91.5 muriatic of ammonia, composed of 62 muriatic gas, and 29.5 ammonia. 34. The scale shews also that for the purpose of ob- taining the whole of the acid in distillation, the quantity of sulphuric acid required is nearly 84, and that the res- idum . of this distillation would be 122 dry sulphate of soda, from which might be obtained by crystallization, 277 glauber's salts containing 153 water of chrystalli^a- tion. Observation.—These and many other similar examples may be performed by motion of the sliderr either up or down, so as to correspond with its place in the adjacent column, which must be of incalculable advantage to the op- erative chemist. 35. When we wish to reduce analytical results, as usually given for two parts, to the equivalent prime ratios, or in other words to the atomic proportions, we must pro- ceed on the following principles. 1. As in all reasoning, we must proceed from what is knewn or determinate, to what is unknown or indeter- TO CHEMISTR\. 33 minate, so in every analysis, there must be one ingredi- ent whose prime equivalent is well ascertained. This is compared as the common .measure, and the proportions of the rest are compared to it. Take fluate of lime to determine the unknown number that should denote the prime of fluoric acid. In the first place 2 primes oxygen =2, combine with I of carbon=0.75, to form the compound prime 2.75 carbonic acid. We likewise know that carbonate of lime consists of 43.6 carbonic acidX 54,4 lime. We therefore make this proportion to determine the prime equivalent of lime 43.6 : 54.4 : : 2.75 : 356= prime of lime. 2. It has been ascertained that 100 parts of dry sulphate of lime, consists of 41.6 lime, and 58.4 acid. Hence to find the prime of sulphuric acid, we make this propor- tion. 41.6 : 58.4 : : 3.565 :=prime of sulphuric acid. There has been obtained from 100 of fluor spar or flu- ate of lime in powder, acted on by sulphuric acid, and ig- nited 175.2* grains of sulphate of lime. Now since 100 grains of sulphate of lime contain as above 41.6 of lime we have this proportion. 100: 41.6 :: 175.2:72.88 = lime corresponding to 175.2 grains of sulphate, and previously existing in the 100 grs. of fluor spar. If from 100 we substract 72.88, the differ- ence 27-12 is the fluoric acjd, or the other ingredient of the fluor, which saturated the lime. Now to find its prime equivalent, we say, 72.83 : 356 : : 27.12 : 1.325=the atom of fluoric acid. Observation—According to Dr. Thomson,,the number 3.625 represents the atom of lime, consequently the atom of fluoric acid would be 1,3015. 36. M. Vauquelin. found that 33 parts of lime saturat- 34 INTRODUCTION ed with sorbicacid, and carefully dried, weighed 100 grs. Hence the difference, 67 grains, was acid. To find its equivalent prime, we say 33: 67 : : 3.56 = the prime of lime : 7.23 = the prime of the acid. But as he brought it to absolute neu- trality by a small portion of potash, we may, according to Dr. Urej take 7.5 for the acid. 37. M. Vauquelin subjected the acid, as it exists in the dry sorbates of lead and copper, to an analysis by fire, and obtained the following results : Hydrogen, 16.8 Carbon, 28.3 Oxygen, 54.9 100.0 Now such an assemblage of the primes or atoms of these elements, must be found as will form a sum total of 7.5 ; and at the same time be to each other, in the above proportions. The following rule is given for the solu- tion, and by a sliding rule it may be found by inspec- tion. Multiply each proportion per cent, by the compound prime, and compare the products by the multiples of the constituent primes. The number of each prime requis- ite to compose the whole, can then be estimated thus, Theory. Experiment. 0.168X7.5=1.2600 or 10 hydrogen =1.25 16.7 16.8 0.283X7.5=2.1225 3 Carbon =2.25 30.0 28.3 0.519X7.5=4.1175 4 Oxygen =4.00 53.3 54.9 7.50 100.0 100.0 If on Dr. Wollaston's scale, we mark with a pencil 2h, 3h, and up to lOh : 2c, 3c, 4c, 5c ; and 2n, 3n, 4n ; respor. TO CIlEMIolIU. 35 lively opposite to twice, thrice, &x. the atoms of hydrogen, carbon and nitrogen, we shall have ready approximations to the prime components, by inspection of the scale. Move the sliding part, so that one of the quantities per cent, may stand opposite the nearest estimate of a mul- tiple prime of that constituent. Thus we know that hy- drogen, carbon and oxygen bear relation to each other of 4, 6, 8 ; of course the latter two that of 3 to 4. But 54.9 oxygen being more than one half of 100, the weight of oxygen in the compound prime is more than the half of 7.5, and therefore points to 4. Place 54.9 opposite 4 oxygen, we shall find 18 opposite 10 hydrogen, and 30.7 opposite 3 carbon. Here wesee that the proportions of carbon and hydroygen are both greater than by Vauquil- in's analysis. Try 51 opposite 4 oxygen, then opposite 3 carbon, we have 28.7, and opposite 10 hydrogen 16.9. 39. If the weight of the compound prime is not giv- en, then we must proceed to estimate the nearest prime proportions, after inspection of those per cent. 40. Chemists differ with regard to their equivalent numbers. There are three systems at present used in England ; 1st, That having oxygen as the root ; 2nd, Thatf having one volume of hydrogen as the root ; 3d That having two volumes of hydrogen as the root, on the hypothesis of Dalton, that two volumes of hydrogen con- tain the same number of atoms, as one volume of oxygen, but this supposition wants proof. Since the volume of hydrogen is equal in weight to 1.6th the weight of the volume of oxygen, the two first systems are mutually convertible by multiplying the number for oxygen, in the oxygen ratio, by 16, or 4X4 to obtain the number in the hydrogen scale, and inverse- ly, it may be re-converted, or by dividing by 16, or by 4X4. INTRODUCTION 41. Dr. Wollaston's scale,and Sir II. Davy's propor- tional numbers are adapted to the idea that water is a compound of 1 hydrogenX7.5 oxygen by weight, or 15X1 by volume. Their mutual conversion is therefore very easy, for by adding to Dr. Wollaston's number its half, the sum is Sir H. Davy's ; consequently, if we subtract from the number of the latter, its third, the remainder is Dr. Wollaston's number. PRACTICAL QUESTIONS. What is called the atomic theory ? What has this theory done for chemistry f What was Sir I. Newton's opinion of atoms ? How is divisibilty thought to be limited ? When, and by whom was the atomic theory first pro- mulgated ? Have the French chemists adapted the atomic theory ? What did Dr. Wollaston introduce into chemistry ? What does he assume as a standard ? What two important propositions have been addu^ red? From what was the first of these laws inferred? How do you illustrate this ? What conclusions did Richter draw ? Illustrate it. How long was Richter occupied in verifying this law ? Do the chemical constituents ever unite in different proportions ? Illustrate it. How are bodies supposed to be composed by this law ? What follows from this ? What is formed when bodies unite in a gaseous state. according to their volume. Illustrate it. TO CHEMISTRY. 37 If this hypothesis and data be correct, what fol- lows ? If hydrogen be taken as unity what follows ? Illustrate this by atmospheric air. Are there any substances whose specific gravities do not correspond with the weights of their atoms ? What must we suppose when the specific quantity is double the weight of the atoms, as that of oxygen ? When does it appear that oxygen puts on this single state ? What instance have we of a compound gaseous body becoming of double the specific gravity ? What is the quantity of acid which the different metal- ic oxides require for saturation according to M. Gay Lussac ? Illustrate this by experiment. What has M. Gay Lussac shewn with regard to the same metal ? What does Berzelius assume as the unit of proportion ? Has Dr. Wollaston's scale been of any advantage to chemistry ? How did Dr. Wollaston proceed ? Give a description of this scale. Illustrate the utility of the scale by an example. What does the scale shew with regard to distillation ? In what manner do you proceed when you wish to re- duce analytical results to equivalent prime ratios ? What is the complex problem of Vauquelin ? And what rule is given for its solution ? How would you proceed on Dr. Wollaston's scale ? Suppose the weight of the compound prime is not giv- en, how would you proceed ? Have all chemists adapted the same equivalent num- bers? 4 38 INTRODUCTION How will you adapt the same scale to the two first systems ? To what idea is Dr. Wollaston's scale and Sir. H. Da- vy's proportional numbers adapted ? CHAP. IV. Of Light.—Caloric. 1. We know little of light but by its effects. It isconsider- ed by most philosophers as a material substance, immedi- ately emanating from the sun and from all luminous bodies, with inconceivable velocity,in right lines, in all directions. 2. Some have considered light as vibrations propa- gated through an elastic medium which is diffused through all space, and in which luminous bodies have the power ofexciting those vibrations, in the same man- ner that sonorous ones produce vibratory motions in the air. 3. It best comports with our ideas of its effects, to suppose light composed of certain particles of matter. 4. " On the supposition that it be matter, its particles must be inconceivably minute, and endowed with mutual and highly repulsive energies." 5. The velocity of light is equal to 195,000 miles in a second of time. 6. A ray of light projected from the sun is about eight minutes in passing from that luminary across the semi- diameter of the earth's orbit, or a space equal to 95,000,000 of miles. Observation. The fixed stars are at least 400,000 times farther from us than the sun ; and it has been calculated TO CHEMISTRY. 23 that a ray of light emitted from one of those luminaries, would be nearly six years in reaching us, so that if one of those stars were struck out of existence at this mo- ment, we should still continue to see it for that space of time to come. 7. The momentum of the particles of light are unap- preciablo, for if they amounted to T^5 of a grain, the force which they must necessarily acquire in moving through so vast a space, would be superior to that of a ball, discharged from a musket with a velocity equal to 1700 feet in a second of time, and sufficient to reduce to powder any obstacle upon which they impinged. 8. It has been calculated that the momentum of light is equal to that of a ball of iron, one quarter of an inch in diameter, moving at the rate of one inch in many mil- lions of millions of Egyptian years ! 9. Such must be the minuteness of the particles, that if, according to Mr. Bowdltch, they were placed in a row so as to form a line one inch in length, and a person at the creation had commenced counting them, at the rate of 120 in a minute, he would have enumerated at the present time a sufficient number to have constituted only a 300,000th part of an inch ! 9. Light is not homogeneous, it is composed of differ- ent coloured rays, possessing different refrangibility.— The prismatic colours have been divided into seven, viz. red, orange, yellow, green, blue, indigo and violet. Red is the least, and violet the most refrangible. 10. The rays of light must be extremely rare, for they cross each other in all possible directions, without the least apparent disturbance. Illustration. A variety of objects may be seen at the same time through a small pin hole in a piece of paper. Now the light, proceeding from these objects, mv.it n™* 40 INTRODUCTION at the same instant through the hole in a great variety of directions, before they arrive at the eye ; yet the vi- *ion is not in the least disturbed by it. 11. The rays differ from each other in their illumi- nating power. Dr. Herschel found that the most intense light existed in the middle of the spectrum of green ray, and diminished towards each extremity. 12. The violet rays possess the power of imparting the magnetic property to steel. Exp. Intercept all the rays except the violet, and having collected them into a focus by a lens, throw it on a needle, and carry it towards the extremity. This is to be repeated several times, and always towards the same extremity ; after some time the needle acquires polarity. 13. Light is considered as constituting an important pxrt of all inflammable substances. In every instance of on the combustible body. Illustration. Examples have been adduced to prove that light depends on the combustible body. The colour of the light emitted is peculiar to the body burned, this would scarcely happen unless the light depended on it ; as the oxide of copper exhibits a green light ; indigo- gene, a blue ; hydrogen, a greenish blue ; sulphur, a pale blue ; phosphorous, a white, &c. 14. Bodies which possess the property of emitting light, either spontaneously or by combustion, so as not to decompose them, are called phosphorescent. illustration. Many chemical compounds possess this property in an eminent degree. In some cases it is ex- cited by heat, or by the solar ray ; in others, spontane- ously, as in dead animals and vegetable substances : in TO CHEMISTRY. 4 J the latter, it probably owes this property to incipient decomposition. Exp. Put half an ounce of herring or mackerel into a phial capable of holding four ounces, with two ounces of water, holding in solution half a drachm of common salt; place the phial in a dark place, and in two or three days, a ring of light will appear on the surface of the il- quid, and by agitation, the whole liquid becomes lumi- nous, and continues in that state for some time. A mod- erate heat increases the luminous quality, but a boiling one destroys it. 15. The light emitted from animal and vegetable substances in a state of decomposition produces no effect on the most delicate thermometer,', hence, it is inferred, that light constitutes a component part of these substan- ces, and that it is the first which is extricated, when the substance containing it, is beginning to be decomposed ; or when the putrefactive fermentation commences. 16. Some living animals possess the phosphorescent power in different parts of their bodies. Illustration. The glow worm and fire fly. 17. The chemical agency of light is very striking in many of its effects.. The beauty of colour and fragrance of vegetables, appear to depend on it entirely; and it has even an influence on their health and vigour. Illustration 1. If light be excluded from a growing vegetable for any length of time, it shoots out rapidly at first, seeming in quest of its great supporter; but if de- nied it, it turns pale, sickens and dies. 2. It is a well known fact, that plants kept in pots in houses, will, in a short time, turn their heads to that quar- ter whence the light proceeds ; if they are turned round, or their position be changed, they will immediately be- gin to return to their former situation ; and if the light 42 l.vrRODUCTION proceed only from above, they will shoot up perpendicu- larly. 18. Plants whi; h grow in the shade, lose in a great measure their inflammable power ; hence, light seems necessary to the very existence of combustible bodies. 19. Light appears to have an influence on the colour of animals, as well as vegetables. Illustrettiun. That part offish which is exposed to the action of the sun's ra\ s, becomes black, or of a dark col- our, while the lower part is white. The plumage of birds is much more beautiful and variegated, in those parts of the world where the sun's rays are the most rowerful. Thus birds possessing the most variegated and vivid colours, are found within the tropics. The hair of animals, living in high latitudes, turns white dur- ing winter. 20. The solar rays have been divided into three dif- ferent kinds. 1. Colorific, or those producing colour.— 2. Calorific, or the those producing heat. 3. Deoxydiz- u:g, expelling oxygen, and restoring the oxides of metals to their metalic state. 21. The intensitj' of the calorific rays increases as their refrangibility decreases. The deoxydizing increase with their refrangibility. 22. Almost all bodies have the property of absorbing the rays of light, but only a few emit it again. They do not, however, absorb all rays indiscriminately; some absorb one coloured ray ; others, another, while they reflect the rest; which is the cause of the different col- ours of bodies. What is called a green body, depends for its colour on the reflection of the green rays of light j red bodies reflect the red rays, while they absorb the others, and so of the rest Hence the inference, that hie different colours of bodies depend upon the affinity TO CHEMISTRY. 43 of each for some particular ray, and its want of affinity for the others. 23. The different sources from which light is emitted in a visible form, are 1. The sun and fixed stars. 2. Com- bustion, which is the act of combination of the combusti- ble with oxygen ; of course, the light emitted must have existed previously combined with the combustible or with oxygen. 3. Heat, when the body becomes lumi- nous by being heated in the fire, it is said to be red hot ; and it is found that all bodies that are capable of endur- ing the requisite degree of heat, without decomposition or volatilization, begin to emit light at the same tem- perature. Illustration. Iron is just visible in the dark : when heated to 635° of Farenheit; it shines strongly in the dark, at 752°; it is luminous in the twilight, just after sunset, when heated to 884° ; and it shines even in broad day light, if its temperature be about 1000°. 24. Percussion, or the striking together of two bodies, is another source of light. Illustration. When flint and steel are struck together, light is produced, which is capable of inflaming tinder, gunpowder, &c. The spark is a small particle of the iron, which takes fire during its passage through the air. This is an instance of combustion. But light is emitted when two quartz stones are smartly struck against each other, though the substances are clearly incombustible. OF CALORIC 25. What is denominated heat is a sensation produ- ced by a substance called caloric, which penetrates all bodies, diminishes the attraction of their several parts, and uniformly expands their dimensions. 26. By means of this powerful agent, solid metals are 44 INTRODUCTION fused ; liquids rarified ; and almost all substances in na- ture are converted into elastic, compressible, or aeriform fluids. . Observation. It has been asserted by Lavoisier, that all bodies of whatever kind, may exist in three different states, solid, fluid and aeriform. 27. Caloric is found to exist under a variety of forms or modifications. It is said to be Free or radiant, and is commonly called heat or temperature ; it is that heat which is perceptible to our senses, and effects the thermometer, whatever may be its degree, or the source whence it is derived. 28. Combined caloric is that which does not effect- the thermometer, and is not perceptible by our senses ; it is retained in bodies by the force of affinity or attrac- tion, and becomes a part of their substance. 29. Heat differs from caloric in this; one is the cause? the other, the effect The latter means that which pro- duces heat ; while the former is merely the sensation. 30. Liquids are combinations of solids with a larger portion of caloric than they naturally contain. Illustration. " Though caloric be the cause of liquidi- ty and the gaseous state,, still bodies in a concrete form contain much of this matter combined. This is known by such processes as lower the temperature of different bodies. So long as any substance can be cooled, so long it has the power of parting with heat ; and we have yet to learn the point at which we could assert that it has parted with all it contains." 31. When caloric is added to water, it becomes va- pour ; and when abstracted from it, it becomes ice. Illustration. In the case of vapour, the caloric forces Kself between the particles of the water, and causes TO CHEMISTRY. 45" them to separate at such a distance, that the force of aggregation is destroyed. 32. Bodies which exhibit properties arising from in- crease or diminution of caloric, are said to be of certain temperature. 33. No substance has had its temperature reduced to 0, in the scale of heat; hence it may be inferred, that the particles of solid Jbodies are never in actual contract. 34. Instruments for measuring the relative degrees of heat, are called Pyrometers and Thermometers, with suitable scales attached, indicating the degrees. 35. The states in which bodies exist, admit of differ- ent degrees of density or consistence, arising for the most part, from the different degrees of caloric which they contain. Solids are of different degrees of density from that of gold to that of jelly. Liquids from the con- sistence of melted glue, or melted metals to that of sihcr. Thz different elastic fluids are susceptible of different degrees of density. 36. Bodies admit of different degrees of consistence without changing their state, merely by the agency of caloric. Illustration 1. The expansion of solids is exhibited by the Pyrometer, which, in principle, is a bar of iron made to fit exactly when cold between two points, and the diameter such as barely to allow it to pass through an iron ring; when heated, it will become sensibly long- er, and it will then be found incapable of passing through the ring. 2. Copper is more expansible than iron; and iron than platinum. 37. Fluids are much more susceptible of dilatation than solids. Illustration. This fact is shewn by the expansion and 46 ' INTRODUCTION contraction of mercury or spirit in a thermometer, or by immersing in water a glass ball with a long neck, and filled to a certain point with any coloured fluid. 38. The degree of expansion produced in different liquids, varies considerably. Illustration. Water is more expansible than mercury, and alcohol than water. Exp. 1. Provide two glass tubes, terminated at one end with large bulbs; fill the bulbs, the one with alco- hol, the other with water, and let the liquids be coloured, in order the better to observe the effect. Hold the bulbs in each hand, for a few moments, you will find the alco- hol dilates with the warmth of the hand, while the water remains stationary. 2. Plunge the bulbs into a vessel containing hot wa- ter, and you see both liquids rise in the tubes, though the alcohol rises much higher than the water, which shews that the former is much more suecoptiblo of dilatation. Observation. Thermometers are constructed on the same principle. 39. A thermometer consists of a tube with a bulb.— Plate 2, fig. 3 A. the glass bulb. B. the tube. C. the scale attached to the tutte. D. the liquid in the tube.— The degree which indicates the boiling point, simply means, that when the fluid is sufficiently dilated to rise to this point, the heat is such, that water exposed to the same temperature will boil; which, as the scale called Farenheit's, is at 212°. When the fluid is so much con- densed as to sink to the freezing point, it indicates that water begins to freeze when exposed to that tempera- ture. 40. Thermometers are constructed in the following manner. A glass tube of a capillary bore is procured, having a small bulb at one end, which, together with pirate n. TJfEHMCmiZ'TElll Bourn* pout/ oSwaOr i JO TO CHEMISTRY. 47 part ef the tube, is filled with purified mercury, which when introduced into the tube is boiled to expel the air or moisture that might be attached to it, and at the mo- ment it is in ebullition, the extremity of the tube, being drawn to a point by means of a blow pipe, is hermeti- cally sealed, to prevent any air from entering the tube. Or if the scale is to be graduated only to 212°, the ball is plunged into boiling water, and the point to which the mercury ascends accurately marked. For the purpose of graduating the scale, the thermometer is plunged into melting ice, and the place where the mercury stands marked. From the freezing to the boiling point on Farenheit's scale, is 180°, or equal parts ; and similar parts are taken above and below, for extending the scale. Observation. Farenheit's thermometer is the one com- monly used in this country and Great Britain. The space between the freezing and boiling points is divided into 180° ; but the scale begins at that point of temperature which is produced by a mixture of pounded ice and mu- riate of ammonia, or muriate of soda, which is 32° lower, making the whole distance 212°. 41. The centigrade thermometer is divided into one hundred degrees, between the freezing and boiling points. The freezing point is marked 0, and the boiling 100°. 42. In Reaumur's thermometer, the space between the freezing and boiling points is divided into eighty de- grees. The freezing point is marked 0, the boiling 80°. 43. The Russian thermometer commonly called De Lisle's, begins its graduation at the boiling point and in- creases towards the freezing. The boiling point is mark- ed 0, the freezing 150. Other fluids besides mercury, are sometimes used, such as linseed oil and alcohol; the latter is used particularly 48 INTRODUCTION for measuring low degrees of temperature, where mer- cury would become solid. For nice chemical experiments, an air thermometer is sometimes used. The bulb of air thermometers is filled with common air only, and its expansion or contrac- tion is indicated by a small drop of any coloured liquor, which is suspended within the tube, and moves up and down according as the air within the bulb or tube expands and contracts. Observation.—In general, air thermometers however sensible to the changes of temperature, are by no means accurate in their indications. 44. The air thermometer of Mr. Leslie, is of a pecu- liar construction ; it is in the form of a double thermom- eter inverted, (Plate 2, fig. 4,) the tube is bent at right angles, placed on a stand, (C.) and has a large bulb at each end, (A. B.) filled with air, the liquor, which is sul- phuric acid coloured, is confined to a portion of the tube, and indicates, by its motion, the comparitive dilatation or contraction of the air within the bulb which points out the relative temperature. Exp. Heat the bulb (A) with the hand, the fluid will rise toward the bulb (B) and vice versa. If both bulbs be placed in the same temperature, the coloured liquor suffers an equal pressure on each side, and no change is effected. 45. This thermometer cannot indicate the tempera- ture of any particular body, or of the medium in which it is immersed. Its use is to point out the difference of temperature between the two bulbs, when placed under different circumstances. It has therefore obtained the name of " Differential thermometer." 46. When the temperature of a body is above the boiling point of mercury, it cannot be measured by a TO CHEMISTRY. 49 common thermometer, because the mercury beginning to be volatilized,would burst the tube. Therefore,when any very high temperatures are to be measured, an instrument called a pyrometer is used for the purpose, that of Wedg- wood's has been considered as the most convenient, it is made of a certain composition of baked clay, which has the peculiar property of contracting by heat, so that the degrees of contraction indicate the temperature to which it is exposed. Observation.'—In Wedgwood's pyrometer, the dimen- sions of a piece of clay are measured by a scale graduat- ed on the side^of a tapered groove, formed in a brass ruler; the more the clay is contracted by the heat, the farther it will descend into the narrow part of the groove. 47. AH elastic fluids whatever undergo the same de- gree of expansion from equal augmentations of tempe- rature. 48. Elastic fluids vary in density more than liquids or solids; the uniformity of their expansibility, may be eas- ily accounted for, on the following principle. If the dif- ferent susceptibilities of expansion of bodies arise from their various degrees of attraction of cohesion, no such difference can be expected in elastic fluids, since in them the attraction of cohesion does not exist, their particles, on the contrary, being possessed of an elastic or repul- sive power; they will, therefore, all be expanded by equal degrees of caloric. 49. Uncombined caloric has a tendency to any equi- librium ; any number of different bodies, at various de- grees of temperature, if placed under similar circum- stances of exposure, acquire a common temperature. Illustration—If there be placed in an atmosphere of 50 INTRODUCTION 55°, iron filings made red hot, boiling water, and other substances of different degrees of temperature, they will all soon become of the same temperature, which may be indicated by the thermometer. 50. Cold is a negative quality, and implies the ab- sence of heat. Illustration.—:Some bodies appear cold to the touch, as quicksilver, marble, &c. This consists in the loss of cal- oric, which that part of the body sustains which comes in contact with the cold body, in an attempt to bring the temperature to an equilibrium. 51. According to a late theory, caloric is composed of particles perfectly separate from each other, every one of which moves with great velocity in a certain di- rection. These directions vary infinitely, the result of which is, that there are rays or lines of these particles, moving with immense velocity, in every possible direc- tion. Caloric then is universally diffused, so that when any portion of space happens to be in the neighbourhood of another, which contains more caloric, the colder por- tion receives a quantity of calorific rays from the latter sufficient to restore an equilibriumof temperature. This radiation not only takes place in free space, but extends also to bodies of every kind. Thus you may suppose that every body whatever, is continually sending forth rr.ys, when the body is surrounded with an elastic medi- um, or in a vacuum. 5.2. These rays are capable of reflection and refrac- tion. Observation. It is well known that the concentration of the solar beams, by means of a concave mirror, is ca- pable of producing an intense heat. 53. Rays capable of producing heat with or without light, proceed from substances on the surface of the globe, TO CHEMISTRY. 51 as well as from the sun, under peculiar existing circum- stances. Exp. 1. The effect is observed by placing two con- cave mirrors one above the other, between which are an ignited body and the thermometer. Exp. 2. Place the concave mirrors opposite each oth- er, with the edges of their faces perpendicular to the sur- face of the earth,and place an iron bullet about two inch- es in diameter, heated to a degree not sufficient to ren- der it luminous, in the focus of one of the mirrors, in the focus of the second mirror, place one of thebbHbs of the differential thermometer, the rays which fall on the first mirror, are reflected in a parallel direction so as to fall on the other mirror, which may be placed at the distance of about ten feet, thence they converge to a focus, and affect very sensibly the thermometer. Exp. 3. Remove the thermometer and place instead of it a wax candle with a small piece of phosphorus in the wick, and after heating the ball, place it in its former place, the candle is immediately lighted. Exp. 4. Substitute a wax taper instead of the bullet. with a view to separate the light from the caloric ; for this purpose interpose a transparent plate of glass be- tween the mirrors, for light passes with great facility through glass, whilst the transmission of caloric is almost wholly impeded by it. But in this experiment, some few uf the calorific rays, together with the light, pass through the glass as ths thermometer rises a little, but as soon as the glass is removed, it will rise considerably higher. 54. In cases where no light is emitted from a hot body, the effect of the radiation of caloric by the mirrors may still be produced. £xp. Let a vessel of boiling water be placed in the INTRODUCTION focus of the upper mirror; place a thermometer in the focus of the lower one, a considerable increase of tempe- rature will be indicated. 55. The manner in which bodies arc affected by rays producing heat, difler in different substances, and is very much connected with their colours. 56. Bodies that absorb the most light and of course radiate heat, are heated the most when exposed to the solar or terrestrial rays. Illustration 1. Black bodies in general are more heat- ed than red, red more than green, green more than yel- low, yellow more than white. 2. Metals are less heated than earthy or stony mat- ters, or than animal or vegetable matters. Polished and bright surfaces are less heated than rough ones. 57. Bodies that have their temperature most easily raised by the action of rays producing heat, are those most easily cooled by their radiation, or at the same tem- perature emit the most caloric. 58. Metals radiate less heat than glass, glass less than some vegetable substances, and charcoal possesses the highest radiating power of any substance hitherto sub- milted to experiment. Observation. Mr. Leslie has made a variety of experi- ments on the radiating powers of different substances: he found by assuming 100 for the radiating power of lamp black, the following substances radiated in proportion, viz.: Sealing Wax, 95 Crown Glass, 90 China Ink, 88 Minium, 80 Isinglass, 80 Plumbago, 7{j TO CHEMISTRY. 53 Tarnished Lead, 45 Polished Iron, 15 Tin Plate, Gold, Sil-> ver and copper, $ 59. Vessels that are intended to contain much heat, should be well polished and bright. Steam or air pipes intended for warming rooms, should be polished in those parts where the heat is not intended to be communicated, and covered with some radiating substance, such as lamp black or plumbago, in those rooms intended to be heated. Vessels for the kitchen should be blackened and not pol- ished in those parts intended to receive heat. The heat- ed surfaces of stoves and fire places should not be metal- lic, but of stony or earthy materials ; in this way much more heat may be communicated by radiation. 60. The following principles are deduced from the observations of Mr. Leslie. 1- The quantity of heat which radiates from any body, depends in a great part on the surface of the body. If the body be covered with black paint, paper, &c. it will radiate eight times as much heat as if the surface were metallic. 2. If the bulb of a thermometer be covered with tin foil the impression of radiant heat upon it is only 1-5 of what it would be on the glass surface of the thermometer. 3. A metallic mirror reflects ten times as much heat from an ordinary fire, or from any heated body, as a sim- ilar glass mirror does, the last reflects the heat from the anterior surface and not from the silvered one. This cir- cumstance exhibits the difference between solar and cu- linary heat. From these facts it seems that metals are eminently disposed to reflect radiant heat, and of course not to absorb it, whereas black paint, paper, glass, &c. are disposed to absorb and not to reflect it; but when the 54 INTRODUCTION temperature is increased, they are eminently disposed to radiate heat. 4. Screens of glass being interposed between the ra- diating body and reflector, completely interrupt the ra- diant heat ; but when heated by the direct rsidiant heat, the thermometer will be affected by their radiation The heat radiated from hot water does not seem capable of being transmitted through glass like the solar heat. 5. Radiant heat suffers no sensible loss in its passage through the air, a greater or less radiant body produces the same effect, provided it subtends the same angle, at the reflector, agreeing with light in this respect. 6. The intensity of reflected heat diminishes inverse- ly as the distance, that is, the density of heat reflected from a concave mirror in any point of the focus, is in] versely as the distance of the hot body from the mirror, whereas in regard to light, the density is known to be uniformly the same, or subject to no change on account of distance. The focus of heat differs from that of light, being nearer the reflector. The heating effect diminish- es rapidly in going out, but slowly inwards towards the reflector. 7. The quantity of heat which a strong radiating surface throws off, is somewhat more than that which is carried off by the atmosphere. This however is contradicted by some. PRACTICAL QUESTIONS. What is light ? How have some considered light? What best comports with our ideas of it ? What follows on the supposition of its being matter? What is its velocity ? How long is it in passing a semi-diameter of the earth's orbit ? TO CHEMISTRY. 56 What are the momenta of the particles of light ? What calculations have been made with regard to the momenta? What with regard to the minuteness of the particles ? Is light homogeneous ? What is the rarity of the rays of light ? Illustrate this. Do the rays differ from each other in their illuminating power ? Does it have any effect on inflammable substances ? Give an illustration. What are phosphorescent bodies ? Give an illustration. How will you prove it ? What is the light emitted from animal and vegetable substances in a state of decomposition ? Do any living animals possess this property ? What is the chemical agency of light? Give an illustration. What effect does the shade have on plants ? Has light any influence on the colour of animals ? Illustrate it. How have the solar rays been divided ? What is their intensity? What effect have almost all bodies on the rays 1 What are the sources of light ? Give an illustraton. Give an illustration of percussion. What is denominated heat ? What is effected by this powerful agent 1 What are the states in which caloric exists ? What is combined caloric ? How does heat differ from caloric ? Give an illustration. 56 INTRODUCTION What effect has it on water ? Illustrate it. What is called temperature ? How do you infer that the particles of solid bodies are not in contact ? What instruments have been invented for measuring the degrees of heat ? What do the states in which bodies exist admit of ? How can bodies be of different degrees of consistence^ without changing their state ? Give an illustration. How do you prove that fluids arc more susceptible of dilatation than solids ? Is the degree of expansion the same in different li- quids ? Illustrate this by experiment. What does the boiling point mean in a thermometer ? How are thermometers constructed ? How is the centigrade thermometer divided ? How is Reaumur's ? How the Russian ? What fluids have been used for thermometers ? Describe air thermometers. Describe Mr. Leslie's air thermometer? Why is it called a differential thermometer ? Will mercury answer for all temperatures ? Describe Wedgwood's pyrometer. In equal augmentation of temperature, what do elastic fluids undergo ? How do you account for the uniformity of their expan- sibility ? What tendency has uncombined caloric ? Illustrate this. What is cold ? Give an illustration. TO CHEMISTRY. 57 What is the theory of radiation ? Of what are these rays capable ? Whence do rays, capable of producing heat with or without light, proceed ? Illustrate this by experiments. What is the effect in cases where no light is emitted from a hot body ? Illustrate this by experiment. What is the manner in which bodies are affected by rays producing heat ? When are bodies which absorb the most light, heated the most ? Give an illustration. What bodies are most easily cooled by their radiation ? What is the degree of radiation of different substances ? What is the radiating power of different substances ? How should vessels be made that are designed to con- tain much heat ? What are the observations deduced from Mr. Leslie's experiments ? CHAP. IV. Continuation of Caloric. 1. All bodies are, in a greater or less degree, con- ductors of caloric. 2. Bodies with respect to caloric are divided into two kinds, good and bad conductors. Illustration 1. Metals and liquids are good conductors of caloric, but silk, cotton, wool, wood, feathers, down, fcc. are bad conductors. 58 INTRODUCTION 2. A short poker or other piece of iron put into* the fire at one end, will very soon become hot at the other ; but apiece of wood or cane of the same length, placed in precisely the same circumstances, may be burnt to ashes at one end, without producingscarcely a sensation of warmth at the other. 3. The facility with which bodies are cooled or heat- ed, is in proportion to their conducting power Illustration. A silken purse containing money, when held to the fire, scarcely becomes warm, while the mon- ey becomes so hot as hardly to be touched, without burn- ing the hand. 4. Brittle bodies are in general bad conductors of heat; hence the surface to which heat is suddenly appli- ed by inordinate expansion, produces fracture. Observation. On this account, vessels made of glass and used over lamps, or exposed in any way to the nak- ed fire, should be as thin as possible, provided they be of sufficient strength to bear their contents. 5. Solid bodies transmit caloric in all directions, Exp. Provide an iron or any other metallic substance, having bars or radii, proceeding from a centre, heat this centre, and you will find that the radii are equally heat- ed. 6. Some bodies conduct caloric more rapidly than others, and this conducting power is not fully accounted for. It has been conjectured that a certain union takes place between the caloric and the particles of the body through which it passes. If this union be strong, the body retains the heat, and parts with it slowly ; if slight, it parts with it rapidly. The conducting power of a body is, therefore, inversely as its tendency to unite with caloric. TO CHF'.riSTRY. 59 Exp. 1. Coat rods of iron and sv'.ass, of equal length, with wax at one end, and expose the other ends to the 6 INTRODUCTION Illustration. On high mountains much less heat is ne- cessary to cause liquids to boil, than at the bases, where the pressure of the* atmosphere is less. Exp. Take a Florence flask about half full of water, and when in the act of boiling take it from the fire, wrap a cold wet linen cloth round the upper part of it, or cork it, plunge it into cold water, and it will immediately be- gin to boil. Illustration. The upper part of the flask being filled with vapour, this was condensed by its caloric being com- pelled to unite with that of the water, of course a vacu- um being produced, it boiled in a much lower tempera- ture. 34. If water can be prevented from going off by steam, it will acquire a degree of heat equal to that of metals when red hot. Illustration. A vessel used for this purpose is called Papin's digester, and is a copper vessel half filled with water. The vessel is furnished with a safety valve, loaded with weights. When the water is so hot as to send off vapour, its escape is prevented until it has ac- quired force almost great enough to burst the vessel, when it raises the valve, which prevents it. Lead and tin have been fused in the water of this vessel, and bones have been totally dissolved. 35. Water does not become hotter by being boiled long in the common way; after arriving at the boiling point, the heat gradually converts a portion of the water into vapour, and the additional heat applied, goes off with the vapour. 36. Ignition is that emission of light which is produc- ed in bodies at a very high temperature, and which is the effect of accumulated caloric. TO CHEMISTRY. 67 37. Ignition is independent of combustion. When a body burns, the light emitted is the effect of caloric alone, and no other change but that of temperature is produced in the ignited body. Illustration. All solid bodies and liquids are suscepti- ble of ignition, or of being heated so as to become lumi- nous. PRACTICAL QUESTIONS. What bodies are conductors of caloric ? How are bodies divided with respect to caloric ? Give an illustration. What is the facility with which bodies are cooled or heated ? Illustrate this. How do solid bodies transmit caloric ? What is the conducting power of some bodies T Illustrate this by an experiment. What is the cause of good conductors of caloric feel- ing hotter or colder ? Illustrate this. Why is flannel clothing warmer in winter than linen ? What bodies are the best conductors of heat, and why t Illustrate this. Why are porous bodies bad conductors ? Is the conducting power of all fluids the same ? Illustrate this. Why do fluids acquire heat quicker than solids ? Illustrate this. What experiments can you shew to prove the truth of the proposition ? What is freezing ? What effect does the constant emission of caloric, from the freezing body, have ? 68 INTRODUCTION Why is it that deep lakes do not freeze in winter? Why does water swell on being frozen ? How does water crystallize in freezing1? Illustrate this. How are the chemical* effects of caloric ? How far can substances be expanded ? How is the increase and contraction of bulk in bodies, that expand I What do bodies require for their liquidity ? How is water converted into vapour or steam ?* Illustrate this. How does the atmosphere dissolve water ? Upon what does the conversion of a fluid into vapour depend ? With what is the tendency of caloric to an equilibrium attended ? What is dew T Explain this on Dr. Wells'theory ? How can liquids that contain a large portion of caloric be converted into vapour ? What is neccessary in order to a liquid's boiling ? Illustrate this. What will be the effect, if boiling water be prevented from going off in steam ? Illustrate this. Can water be made hotter by being continued boiling' What is ignition ? How doe6 ignition differ from combustion ? TO CHEMISTRY. 69 CHAP. V. Of combined Caloric—Specific and Latent Heat. 1. Bodies of a different nature, heated to the same temperature, do not contain the same quantity of caloric. 2. In order to raise the temperature of different bo- dies the same number of degrees, different quantities of caloric are required. Illustration. If lead,chalk and milk of each equal weights be placed in a hot oven, or furnace, they will be gradu- ally heated to the temperature of the oven ; but the lead first, the chalk next, and the milk last. This is probably owing to the different capacities of bodies for caloric. 3. Capacity for caloric is a certain disposition of bo- dies to require more or less caloric for raising their tem- perature to a certain degree. Illustration. The meaning is pretty nearly the same as when the term is applied to vessels ; in these, the ca- pacity is greatest in that which will contain most; so it is with regard to caloric. Thus iron has a less ca- pacity for caloric than wood, and quicksilver has a less capacity for it than water; because it requires a smaller quantity of it to raise its temperature to a given degree on the thermometer. 4. The caloric that is employed in filling the capaci- ty of a body is not free caloric, but is combined in the body, and is, therefore, imperceptible. Illustration. If you lay your hand on a hot body, you feel only the caloric that leaves it and enters your hand. The thermometer in the same manner is affected only by the free caloric which a body transmits to it 70 INTRODUCTlOfl 5. Specific caloric is the relative quantity of caloric which different species of bodies of the same weight and temperature are capable of containing; it is often called heat of capacity. Illustration 1. In the case of the lead, chalk and milk, the two latter having a greater capacity for caloric than the lead, a greater proportion of that fluid became insen- sible in those bodies. 2. The difference could not proceed from the differ- ent conducting powers in those bodies, for if the different times they took in heating.proceeded fromtheir different conducting powers, they would each have acquired an equal quantity of caloric. This we shall shew is not the case. Exp. Plunge the lead, chalk and milk, into three equal quantities of water, each of the same temperature, on examining the three vessels of water you find the one in which the lead was immersed to be least heated, and that which contained the milk to be most heated of all. 5. The thermometer indicates no specific heat of bod- ies, for it can only be affected by free caloric which raises the temperature of bodies. Exp. 1. Mix two fluids of different temperatures, let the one be 50° and the other 100°. If the two bodies happen to have the same capacity for caloric, the tempe- rature will be 75°. 2. Mix a pound of mercury at 50°, arid a pound of water at 100°, the capacity of the two substances not be- ing equal, the temperature of the mixture will be 80°, so that the water will have lost only 12 degrees, and the mercury will gain 38 degrees. Hence it may be in- ferred that the capacity of mercury for heat is less than that of water. TO CHEMISTRY. 71 0. Latent heat is that, portion of caloric which is em- ployed in changing the etate of bodies, or in converting solids into liquids, or liquids into vapotar. Observation. By most chemists it is used in-the same sense as specific caloric. 7. When a body changes its state from a solid to a liquid, or from a liquid to a solid, its expansion occasions a sudden and considerable increase of capacity for heat, consequently it immediately absorbs a quantity of caloric, which becomes fixed in the body which it has transform- ed, and as it i3 perfectly concealed from our senses, it has obtained the name of latent heat. 8. The difference between specific and latent heat is this, the formar is that which is employed m filling the capacity of a body for caloric in the state in which this body actually exists ; latent heat is that which is employ- ed only in effecting a change of state. Exp. The mercury of a thermometer plunged into a vessel filled with pounded ice will immediately descend to 32° If then the vessel be immersed in boding wat- er, the mercury will not nse during the whole time that the ice is liquefying. Illustration. The heat which is continually flowing in- to the ice does not affect the thermometer, because it is all employed in converting ice into water As the ice melts, the caloric becomes latent in the new formed li- quid, therefore cannot raise its temperature, consequent- ly the thermometer will remain stationary until tx> whole of the ice be melted. It will then beg.n to r.se because the caloric no longer remains latent, but free. 9. The capacity of water for caloric is greater than that of ice, more heat is therefore required to raise a thermometer plunged into water than when placed in ice «r snow 72 INTRODUCTION Exp. Put some snow or pounded ice which has been cooled 7 or 8 degrees below the freezing point into a glass vessel, in which there is a thermometer ; apply the heat of a lamp and the mercury will ri:e gradually to 3-2°, where it will remain stationary until the whole is molted, when it will again rise, though much slower. It continues to rise until the water begins to boil, when it again becomes stationary. The caloric is now no long- er free to affect the thermometer, but is employed in converting the water into steam, in which it becomes stationary. This is sometimes called caloric of fluidity, or evaporation. 10. When a body passes from a liquid to a solid, or from vapour to a liquid, the latent caloric is evolved and becomes free. Illustration. When water, as in the slacking of lime, is converted from a liquid to the solid state, the caloric which caused the water to continue fluid is evolved and the sensible or free caloric is increased. 11. When a body is condensed or has its volume di- minished, whether by mechanical force, as in condensing the air in the receiver of an air pump, metals under the hammer,&c. or by chemical combination, in which concen- tration takes place, the latent caloric is pressed out, and consequently, the sensible or free caloric is increased. Exp. Fill a wine glass about half with water, and pour upon it sulphuric acid, a very high temperature is produced, which is caused by the disengagement of latent caloric. 2. Pour into a phial containing a solnti on of muriate lime, a few drops of oil of vitriol, sulphuric acid, the whole will 1-3 converted into a solid mass, at the sametme the bot- tle becomes very much heated. 3. A cold tar of iron, by hammering on an anvil, may be made red hot. TO CHEMISTRY. 4. Prepare a hot saturated solution of sulphate of so- da, Glaubers salts, in a flask ; when it is hot, cork it, and keep it in this situation until cold. Then take out the cork and let the air into the vacuum made by corking it when the salt will suddenly crystallize, while at the same time, sensible heat is disengaged. 12. When a body is rarefied or has its volume increas- ed, as in exhausting the air from the receiver of an air pump, the caloric is absorbed and the sensible heat is di- minished. PRACTICAL QUESTIONS. Do all bodies contain the same quantity of caloric ? How are different bodies raised to the same degree of temperature ? Give an illustration. What is capacity for caloric ? Illustrate it. What is the caloric that is employed in filling the ca- pacity of a body ? Illustrate it. What is specific caloric ? Illustrate it ? May not the difference proceed from the different pow- ers of those bodies in conducting caloric 1 Illustrate this by experiment. Does the thermometer indicate the specific heat of bodies ? What is latent heat? Why is it called latent heat ? What is the difference between specific and latent heat? What is the capacity of water and ice for caloric ? Illustrate this by an experiment 7 *4 INTRODUCTION When does the latent caloric become free in bodies When is the sensible or free caloric increased ? Illustrate this by experiment. When is the sensible heat diminished? CHAP. VI. Of Oxygen and its combinations. 1. Oxygen is the principle upon which most of thf chemical phenomena of atmospheric air depend. Obso-vation. Oxygen was discovered by Mayow, in 1674, and called by him igneo-aerieal spirit. It-was named dephlogisticated air by Dr. Priestley, who examined it in 1774. Scheelein 1777, called it empyreal air; Condor- cet vital air; and Lavoisier, oxygen, which term is now universally adapted by chemists. 2. Oxygen has never been procured in an uncombin- ed state. Its greatest purity is that of oxygen gas. 3. The term Gas is given to any fluid capable of ex- isting in an aeriform state, under the pressure and tempe- rature of the atmosphere. 4. Oxygen has never been made solid by any degree of cold, and therefore differs in this respect from-vapours which may be condensed into a liquid, and converted in- to a solid. 5. Sir II. Davy thinks that gases owe their perma- nently elastic state to the presence either of positive or negative electricity.—(see electricity.) 6. Oxygen and oxygen gas are used as synony.nou?, though str.cktly speaking, oxygen is the base of the gas known by that name. TO CHEMISTRY. 75 7. Oxygen is one of the most important agents in na ture, it has a share in almost every process, either natu- ral or artificial. To procure oxygen gas in large quantities proceed as follows : Take an iron bottle or retort, (B. Plate 3, fig. If) and having charged it with powdered black oxide of manganese, place it in the furnace, (A.) on a small stand above the grate, lute to the beak of the retort a tube (E.) passing under the jar (D.) which is filled with water standing on a shelf in the pneumatic cistern or water bath, C. Kindle a fire in the furnace, when the retort becomes red hot, the gas passes over and rises in the jar in the form of bubbles, displacing the water. Obseiroation. Instead of the black oxide of manganese, the red oxide of lead may be used, in that case a glass re- tort, and Argand's lamp may be substituted for the above, fig. 2, E F the lamp, C the retort, D the stand—e. e. e. rings, with screws for holding the different vessels necer- sary in the use of this furnace. 8. Oxygen gas is permanently elastic, compressible, inodorous, transparent and insipid. 100 cubic inches at 60°F; barometer at 30 inches weighs 33.82. 9. The specific gravity of oxygen in relation to wa- ter, is as 0.00135 to 1.00000 ; and in relation to hydrogen as 15 to 1. In relation to. an equal volume of atmos- pheric air as 1.1088 to 10000. 10. Its specific caloric or capacity for heat is 0.8848 to an equal bulk of atmospheric air as 1.0000, 11. The specific heat of water being unity, that of oxygen will be,0.2361. 12. Oxygen gas is a supporter of combustion. The quantity of caloric liberated during combustion depends entirely on the quantity of oxygen gas combined in a giv» en space of time with the combustible body. 76 INTRODUCTION Exp. 1. Immerse an inflamed taper in oxygen gas, it burns with great splendour, and is much more rapidly consumed than in atmospheric air. 2. Blow out the taper and when the wick is merely glowing, immerse it in oxygen gas, it is immediately re- kindled with a slight explosion. 3. Bend a small steel or iron wire spirally, attach to it a piece of lighted tinder, and having placed it in ajar <']led with oxygen gas, the metal will burn with great brilliancy and throw cff he^Uiful white scintillations which are iron combined with one portion of oxygen now called protoxide of iron. 4. If sulphur, phosphorus or charcoal be burned in oxygen gas, the combustion will be intensely vivid, and acids will be produced, of greater or less strength, accor- ding to the proportion of oxygen they contain. Illustration. Phosphorus with a small portion of ox- ygen forms an oxide of phosphorus ; with a larger por- tion, phosphorus acid, and with the largest, phosphoric acid. 13. Oxygen gas is the only one that can be breathed by ap/imals for any length of time, with impunity. The power of atmospheric air in supporting respiration is ow- ing to the oxygen. 14. In respiration a quantity of atmospheric air is taken into the lungs, the oxygen disappears and a quan- tity of carbonic acid gas equal in bulk is formed in its ftead. A reciprocal influence is exerted between this aerial fluid and the circulating blood, and the continuance of life is dependent upon ihe due exercise of this influ- ence which appears by the conversion of oxygen into carbonic acid. 15. Animals confined in oxygen gas will live four or TO CHEMISTRY. 77 five times longer than when confined in atmospheric air. , 16. It may be breathed by men for some time with- out producing any other effect than a sensation of warmth and slight stricture of the chest. 17. Oxygen forms about 22per cent of the atmospher- ic air, the rest is nitrogen or azotic gas, except perhaps a small quantity of carbonic acid. 18. With hydrogen it forms water in the proportion of eighty five oxygen, and fifteen hydrogen. Water which is perfectly insipid contains more oxygen than any of the acids to which it is essential. Illustration. When any fluid capable of undergoing fer- mentation is exposed to the atmosphere and in a moderate temperature, it absorbs oxygen and is changed to an acid. 19. Oxygen is separated from many of its combina- tions by the influence of the solar rays; especially from water Exp. Place a tumbler of clear spring water in the rays of the sun for a few minutes, small bubbles of oxy- gen gas will be formed on the bottom and sides. 20. Oxygen combines with all the metals, and in that state they are called metallic oxides, depriving them of their metallic lustre, and giving them an earthy or rusty appearance. 21. Some of the metals become oxidized, or are rust- ed by mere exposure to a damp atmosphere. Exp. Iron exposed to the weather soon becomes rus- ty by attracting oxygen from the air or water. 22. All oxides are heavier than the metal, in propor- tion to the quantity of oxygen with which they are com- bined. , 23. Many of the metals are capable of combining with different proportions of oxygen. Those with one 78 INTRODUCTION portion are called protoxides ; of two, Deutoxides ; those of three, tritoxides. 21. A metal combined with the greatest proportion o f oxygen is called peroxide. 25. In general the least simple bases unite with oxy- gen in the greatest variety of proportions. 26. Oxygen undergoes various changes in its prop- erties by its union with many oxidizable substances. The compounds are fluid, solid, opaque, coloured, incapable of supporting inflammation, and deleterious to animal and vegetable life. 27. Oxygen has a powerful effect on vegetable col- ours, producing the various tints of shade which we be- hold in this department of nature. Illustration 1. Yarn when first taken from the blue vat, is green, but on exposure to the air, it imbibes oxygen, and is changed to a deep blue. 2. The Buccinum, which is employed in dying pur- ple, undergoes a remarkable change in contact with ox- ygen, the liquor naturally yellow, becomes oxidized on exposure to the sun and air; it passes through various shades of yellow, green, crimson, kc. at length it becomes purple. 3. It is well known to dyers that they cannot pro- duce a good black without exposing their stuffs to the air. 28. Vegetable colours fade on exposure to the sun, which is probably owing to this principle ; the oxygen which previously existed in the colouring matter in a solid form, is rendered aeriform by the rays of the sun, and is evolved in the form of gas. 29. Oxygen gas of great purity may be obtained from the green leaves of plants ; lngenhouz first obtained it TO CHEMISTRY. 79 from these substances for some of his most brilliant ex- periments. 30. It is obtained in the greatest purity from chloride of potassium, by simply decomposing it with a very gen- tle heat. This, however, is not an economical method. PRACTICAL QUESTIONS. What is oxygen ? Who discovered it, and what was it named ? Has oxygen been obtained in its pure state ? What is gas ? How does it differ from vapour ? To what does Sir H. Davy suppose that gases -owe their permanently elastic state ? What is oxygen, strictly speaking ? Of what use is oxygen in nature ? How is oxygen gas produced ? What are the characteristics of oxygen gas ? What is its specific gravity ? Is oxygen gas a supporter of combustion ? On what does the quantity of caloric, during combus- tion, depend ? Illustrate it by experiment. What is the supporter of respiration ? Describe the process. What effect does oxygen gas have on animals, when confined in it ? What effect on man ? What proportion does it form of the atmosphere ? What proportion does it form of water ? How is oxygen separated from many of its combina- tions ? Does it combine with the metals ? How are some of the metais oxidized I 80 INTRODUCTION What is the weight of the oxides ? Do the metals combine with different portions of 0x3 * gen, and what are those combinations called ? What is the greatest metallic oxide called ? Does oxygen undergo any changes in its combinations? Has oxygen any effect on vegetable colours ? Illustrate it. Why do vegetable colours fade, on exposure to the sun ? How can this gas of great purity be obtained ? From what is it obtained in the greatest purity ? CHAP. VII. Of Azote or Nitrogen. 1. Nitrogen is the basis of the nitric acid; it exhibits itself in its simplest state as a gas. Observation. This gas was discovered by Dr. Ruther- ford, in 1772, and by Mr. Scheele, 1776. It was former- ly called azote, because it was destructive to animal life. 2. Nitrogen constitutes about 0.78 parts in bulk of atmospheric air. 3. The use of nitrogen in atmospheric air is to dilute the oxygen gas, in order to render it adequate for the several functions which it is destined to perform in the economy of nature ; thus mollifying the activity of the latter, which in its pure state, would be too powerful. 4. It may be readily obtained from atmospheric air, by removing the oxygenous part of it. Exp. 1. If a portion of iron filings and sulphur mois- tened with water, be put into a flask filled with common TO CHEMISTRY. 81 air, the oxygen will, in a short time, be absorbed by the metal and sulphur, while the nitrogen gas will remain. 2. Phosphorus inclosed in a similar vessel with com- mon air, will produce a similar effect. The phosphorus will be oxidized or converted into phosphoric acid, while the nitrogen will remain. 3. Under a bell glass which is full of atmospheric air, standing over water, introduce some sulphuret of potash, which in a few days will absorb all the oxygen and leave the nitrogen pure. 4. Any kind of muscular flesh cut small, and put in a retort with some diluted nitric acid, will, by the applica- tion of heat, produce nitrogen gas. 5. Nitrogen gas when pure is permanently elastic? inodorous and insipid. It converts vegetable blues to green. It is fatal to animals confined in it. 6. Nitrogen immediately extinguishes flame. Exp. Procure a jar of nitrogen gas and immerse in it a burning taper. It is immediately extinguished, as ef- fectually as if thrust into a vessel of water. 7. When nitrogen gas is mixed with oxygen in the proportion of four parts of the former to one of the lat- ter, it produces a mixture resembling atmospheric air. 8. The specific gravity of nitrogen to that of water is, as 0.0012 to 1.0000, and to that of hydrogen as 13 to 1. 9. It dissolves phosphorus and carbon in small quan- tities. 10. Nitrogen has been thought by some to be a com- pound of hydrogen and oxygen, containing a less propor- tion of oxygen than water, composed of 6 atoms hydro- gen, and 1 oxygen, or by weight of 44.4 of the former, and 55.6 of the latter. But this fact, if it be one, has not been fully demonstrated. 82 INTRODUCTION 11. Nitrogen constitutes an ingredient in animal sub- stances, and this in some measure distinguishes them from vegetable ones, where it is very rarely found. 12. Nitrogen unites with oxygen in two states ; in mixture, they constitute atmospheric air ; in chemical combination, the nitric acid. 13. Nitrous acid is nitric acid holding nitrous gas in solution, and is the aqua fortis of the shops. 14. There are two combinations of nitrogen and oxjr- gen in a gaseous state, viz. nitrous oxide and nitrous gas. 15. Nitrogen combines with hydrogen and forms am* monia. PRACTICAL QUESTIONS. What is nitrogen ? Who discovered it, and when ? What proportion of the atmosphere does it constitute ? What is its use in the atmosphere ? How can it be obtained? What are its characteristics ? Will it support flame ? How can you form atmospheric air ? What is the specific gravity of hydrogen ? What does it dissolve ? What has it been considered to be by some ? How are animal substances distinguished from vegeta- ble, with regard to nitrogen ? In how many states does nitrogen unite with oxygen ? What is nitrous acid ? How many chemical combinations are there of ni trogen with oxygen ? What is ammonia ? TO CHEMISTRY. #3 CHAP. VIII. Of Hydrogen. 1. Hydrogen united to caloric is one of the constitu- ents of water; it has never been obtained but in combi- nation with caloric, with which it forms nitrogen gas. Observation. Its properties were first examined in 1756 by Mr. Cavendish, 2. It is one of the most abundant principles in nature ; it forms about 1-9 of all the water of the globe, and is a constituent of oil, bitumen, ardent spirits, ether, alcohol, and of all the component parts of animal and vegetable substances. . 3. Hydrogen is invisible and elastic, and between 12 and 13 times lighter than common air; hence its use in filling balloons, Exp. Fill a bladder with hydrogen, having a small aperture with a stop cock ; prepare a strong solution of soap in water, and having fitted a tobacco pipe to the stop cock, dip it in the soap and water, and take up a few drops, having turned the cock, squeeze out some of the gas so as to form a bubble, which, when disengaged, will ascend rapidly to the ceiling of the room, like air balloons. 4. This gas has a smell resembling garlic. It is ut- terly unfit to support respiration or combustion. Illustration. Although it may be taken into the lungs, it cannot be breathed by man for more than a minute ; small animals die in it, in a much shorter time. 5. Its specific gravity to that of oxygen is as 1 to 16. 6. Water is composed by weight of oxygen, 88.24, hydrogen, 11.76 in the 100, and may be obtained by 8 1 INTRODUCTION CQmbustion, in this way hydrogen combines with the oxygen, and their opposite electricities are disengaged in the form of caloric ; by the loss of caloric the two gases are condensed into a liquid. Illustration. In this process, the two gases are chem- ically combined and not mixed as is the case with oxy- gen and nitrogen in atmospheric air. 7. Hydrogen is obtained by the decomposition of wa- ter ; the best way of obtaining it for experiments is, as follows. Take sulphuric acid diluted with five or six times its weight of water, and pour it on a quantity of iron or zinc filings in a gas bottle, plate 2. fig. 3, con- nected with a pneumatic cistern. An eflervesence takes place, and the hydrogen is evolved, which may be col- lected in a jar over water, while the oxygen unites with the metal and becomes solidified. The water is decom- posed in consequence of the great affinity of the metal for oxygen. If the metal be taken out and dried, it will be found to have gained in weight equal to the oxygen absorbed. Observation. It has been conjectured that hydrogen is a metal in an aerial form. 8. Water may be decomposed by electricity, or the action of the voltaic battery. Exp. 1. Fill a piece of glass tube with water, plate 3, fig. 3, and cork it at both ends ; through one of the corks introduce the positive wire of the battery, and the negative through the other, let the ends of the wires be about l-8th of an inch apart. Each wire decomposes the water, the positive by combining with its oxygen, which is negative, and the negative with the hydrogen, which is positive. The bubbles which appear to proceed from the positive wire, are the result of the decompos.t on of water by that wire. For the positive electricity having ,p, TO CHEMISTRY combined with some of the oxygen of the water, the particles of hydrogen which were combined with that portion of oxygen, are set at liberty and appear in the form of small bubbles of gas. The negative fluid hav- ing in the same manner combined with some of the hy- drogen of the water, the particles of oxygen that were combined with it are set free, and emitted in a "aseous form. Observation. The wires used in this experiment should be made of platina, which does not combine readily with oxygen, otherwise the oxygen would combine with the metal, and the hydrogen only would be disengaged. Exp. 1. The gases in the above experiment were mixed, but they may be collected separately, in the fol- lowing manner. Instead of one tube, let two be used, fig. 4, e. d. both tubes being closed at one end and open at the other ; fill these tubes with water, and place them standing in a glass of water e. with their open end down- wards ; connect the wires a. b. which proceed from the interior of each tube, the one with the positive, and the other with the negative end of the battery; the water in the lubes will be decomposed, hydrogen will be given out round the wire in the tube connected with the posi- tive end of the battery, and oxygen in the other ; the gases will be evolved exactly in the proportion of two measures of hydrogen to one of oxygen. Exp. 2. Water may be decomposed by means of heat in the following manner. Place a gun barrel across a furnace, inclining a little. To the extremity, lute on a small glass retort, containing a quantity of water, and to the other end is to be luted a tube connected with a pneu- matic cistern. Two fires are now to be lighted, one in the furnace, sufficient to keep the gun barrel red hot and the other in a^lamp under the retort When the 8 86 INTRODUCTION water boils, the vapour will pass through the tube, where it will be decomposed ; the oxygen is attracted by the metal and the hydrogen is evolved and passes out of the tube, where it may be caught in jars, or inflamed at the mouth of the tube. 9. From the combustion of oxygen and hydrogen, wa- ter is produced. Exp. Take the gases collected by the voltaic ex- periment No. 2, that is to say, two volumes of hydrogen, and one of oxygen, and having mixed them, set fire to them by an electric spark, both gases will entirely dis- appear, and a small quantity of water will be obtained. 10. Hydrogen gas in combustion has the property of producing very ^peculiar sounds in glass. Exp. Provide a phial with a cork stopper, through which, pass a glass tube or piece of the stem of a tobac- co pipe ; into this pipe, half filled with water, put a quantity of iron filings, to which, add of sulphuric acid a quantity equal to one third of the water. Replace the cork, and the hydrogen gas will be liberated through the tube, to which after the atmospheric air is disengaged, apply the flame of a candle, the hydrogen will immedi- ately take fire and burn with a clear flame. This has been named the philosophical candle. If a piece of glass tube about two feet in length and one inch in diameter, open at both ends, be placed over the flame, a noise similar in some measure to an Eolian harp will be produced Illustration. The cause of this is probably owing to a quick vibrating motion of the glass, occasioned by the successive formation and condensation of small drops of water on the sides of the glass tube, and the air rushing in to replace the vacuum formed. TO CHEMISTRY. gf 11. The flame of a candle or lamp is produced by the hydrogen which is contained in the wax, tallow or oil, which being converted into gas by the heat of the can- dle, combines with the oxygen of the atmosphere, and flame and water result from the combination. The can- dle must come in contact with some ignited body in order <<-> give the first impulse to the combustion, it afterwards goes on of itself, because the candle finds a supply of ca- loric in the successive quantities of heat which result from the union of the two electricities, given out by the gases during their combustion. 12. Flame, in general, is owing to the formation and combustion of hydrogen gas, or rather hydro-carbonate, which is an union of hydrogen with carbon. 13.. The regular tapering shape of flame, is owing to the stream of hydrogen gas, which issues from the burning body ; the combustion of the gas is completed at the point where the rlame terminates, it is there con- verted by its union with.oxygen into aqueous vapour. Exp. Invert a tumbler over the flame of a candle, in a few minutes the inside becomes covered with vapour. 14. Hydrogen gas when inflamed burns gradually, but when mixed with atmospheric air or oxygen, it de- tonates violently. Exp. 1. Fill a bladder, having a stop cock, with hy- drogen gas, adjust to the cock a small pipe, dip this in soap suds, and having blown up bobbles, apply to them a burning taper, and a loud detonation will ensue. 2. Fill a small jar or phial with a mixture of one part of oxygen and two parts of hydrogen, and apply the mouth to the flame of a candle or taper, it will explode with a loud noise. Illustration. By the application of flame, the hydro- gen is decomposed or burnt, and forms water, by its chemi- cal union with oxvgcn. INTRODUCTION 15. Hydrogen forms a constituent In pit coal, and may be disengaged or combined with carbon, called car- buretted hydrogen gas. 16. Gas lights are produced from carburetted hydro- gen gas, conveyed through a tube of a very small bore, at the extremity of which, it is kindled and burns as long its the supply continues, without wick or any other sub- stance whatever, except the gas. Exp. Pulverize a small quantity of coal and put it in- to the bowl of a tobacco pipe, cover the coal closely over with clay and place the bowl in the fire. In a few min- utes a stream of carburetted hydrogen gas will issue from the end of the pipe, which may be inflamed with a light* ed taper, and will burn for a considerable time. Observation. On a large scale, the carburetted hydro- gen gas is obtained from coal in iron retorts, the gas at its formation is made to pass through two or three large vessels of water, in which it deposits foreign ingredients which are carried over with it from the retort, thence it is conveyed with uniform velocity by means of pressure, to the destined places. 17. The gas produced in coal mines commonly called fire damp, which, until within a few years occasioned the destruction of so many lives in the mines of England, is light carburetted hydrogen,• this gas being inflammable when it is approached with a candle, takes fire and pro- duces violent explosions. 18. It has been found that this gas will not inflame by iron wire heated red hot ; so that if a lamp be inclos- ed in a wire gauze of certain dimensions, it may be made to subserve all the purposes of affording light to the men in the -mines without danger of explosions. On this principle, Sir II. Davy's safety lamp is formed. TO CHEMISTRY. gg 19. Hydrogen unites with sulphur, phosphorus and carbon. It is then called sulphuretted, phcsphuretted and carburetted hydrogen gas. 20. Phosphuretted hydrogen gas possesses the prop- erty of being inflamed, when exposed to atmospheric air. Exp. Introduce into a retort a diluted solution of caustic potash, with a small piece of phosphorus, plunge the beak of the retort into water, heat the retort by means of a lamp until the liquor boils, bubbles will pass out of the retort, which, as soon as they reach the sur- face, will inflame. Observation. This is one of the most interesting ex- periments in chemistry. 21.. Sulphuretted hydrogen gas is produced by the decomposition of animal and vegetable substances. Observation. It is this gas which causes the fetid effluvia which arises from vaults and drains. It is like- wise found in some mineral waters. 22. Hydrogen united with oxygen in certain propor- tions, produces the most intense heat hitherto known ; for this purpose it has been applied in an instrument, called an oxy-hydrogen blow pipe. PRACTICAL QUESTIONS. What is hydrogen ? Does it exist in great quantities in nature ? What are its characteristics ? What other properties has it ? Can it be taken into the lungs ? What is its specific gravity ? What portion has it, in the composition of water ? How does it form water ? Is it by mixture, or chemical combination ? 8* 90 INTRODUCTION How is hydrogen obtained ? How do you decompose water by electricity 1 Of what should the wires in this experiment be made '.' How can you collect the gases separately by electrici- ty? How do you decompose water by means of heat ? What experiment have you to shew, that water is formed by combustion ? What peculiar effect does hydrogen, in combustion, have on glass 1 How do you perform this experiment ? How do you account for this ? How is the flame of a candle or lamp produced 1 To what is flame, in general, owing ? Why is it regular and tapering 1 I low do you produce a detonation with hydrogen ? What is the gas obtained from pit coal ? flow are gas lights produced ? How can you imitate the gas lights ? How is this gas obtained on a large scale ? What is fire damp ? On what principle is Sir H. Davy's safety lamp con- structed ? What is sulphuretted, phosphuretted and carburetted hydrogen ? What property does phosphuretted hydrogen gas pos- sess ? How would }'ou illustrate this by experiment 1 How is sulphuretted hydrogen gas produced ? What is the consequence of the union of oxygen and nydrogen ? TO CHEMISTR*. qj CHAP. IX Of Sulphur. 1. Sulphur or brimstone is sometimes found in a state of purity, but more frequently mixed with other sub- stances ; particularly with metals. 2. In the state of combination, the several metallic substances combined with sulphur, were called Pyrites ; by the new nomenclature, sulphurets. Illustration. Sulphur united with iron, forms martial pyrites; united with copper, copper pyrites; or sulphu- ret of iron, or copper. 3. Sulphur also exists in vegetables, and it is emitted from animal substances in a state of putrefaction, com- bined with hydrogen. 4. Sulphur is obtained by roasting or exposing met- als to heat, sufficient to drive off the sulphur which is condensed on the top of the furnace. 5. The characteristics of sulphur are, it is brittle, electric, fusible at 220° Farenheit, burns with a pale blue flame at 302°, and a bright white one at 370°. 6. Its specific gravity is 1.99 to 2.325. 7. When sulphur is kept melted in an open vessel for some time, at about 300° F. it becomes thick and vis- cid, and if it be then poured into a bason of water, it appears of a red colour and ductile, like wax. 8. The substance sold under the name of flowers of sulphur, is merely sulphur sublimed or minutely divided by means of heat Exp. Place some lumps of sulphur in the cucurbit, such as was used for alcohol and sulphur. Plate 2, fig. 4. ' And having placed the head upon it, set it in a sand bath, 92 INTRODT't 1 ION which must be gently heated. The sulphur soon begins to melt and immediately a thick white smoke rises, which is gradually deposited within the head, where it condens- es against the sides somewhat in the form of vegetation,, whence its name. When first formed, it is of a pungent and offensive smell. 9. Sulphur in combustion in close vessels, combines with the oxygen within the vessel, and forms a com- pound totally different from sulphur in its pure state. Exp. Put a small quantity of the flowers of sulphur in- to a tea cup, and place it in a saucer filled with water, with a hot iron set fire to the sulphur. It burns with a faint bluish flame, invert over it a bell grass, white fumes will arise from the sulphur and fill the vessel, at the same time the water will rise in the receiver: the water absorbs the gas and acquires acid properties which did not previously exist in the sulphur Illustration. Sulphur in the state of vapour absorbs the oxygen in the receiver, and assumes the form of an elastic fluid of a pungent and offensive smell. A chemi- cal combination of oxygen and sulphur takes place, and a true gas is formed which would continue so under the pressure and temperature of the atmosphere, if it did not combine with the water to which it imparts its acid taste and all its acid properties. The oxygen in this case is the acidifying principle. 10. Sulphur combines with oxygen in four definite proportions, forming an interesting class of acids, viz. : The sulphurous, hypo sulphurous, sulphuric and hypo-sul- phuric From these combinations it is inferred that the prime equivalent of sulphur is 2, and the density of its vapour is 1.111, equal to that of oxygen. Observation. In the last experiment the acid formed was the sulphurous, which is the weakest degree of acid TO CHEMISTRY. 93 ification ; when fully satutrated it is the sulphuric and hy- posulphuric. Exp. Provide a large glass receiver with a glass stop- per at top, and having filled it with oxygen gas in the pneumatic cistern, slide it off the shelf into a plate con- taining water, then introdnce a piece of sulphur into the receiver through the opening at the top and with it a small piece of lighted tinder. It burns with a very bril- liant blue light, and quickly fills the receiver with va- pour, which is condensed in the water below and forms sulphuric acid diluted, which may be condensed by evap- oration. 11. Sulphur has hitherto been considered as a sim- ple substance, but recent experiments seem to shew that it is combined with a small portion of hydrogen and perhaps of oxygen. Illustration. Sir H. Davy observed, on submitting sul- phur to the action of the voltaic battery, that the negative wire gave out hydrogen ; and by the combustion of sul- phury small quantity of water was produced which indi- cated the presence of hydrogen. 12. Sulphur combines with the metals, earths and al- kalies, forming hard substances called Sxdphurets. Exp. 1. Heat an iron bar red hot, and apply to it a roll of sulphur, the latter becomes melted, and the drops that fall will be found to be a sulphuret of iron. 2. Boil muriate of ammonia, lime and sulphur togeth- er, the compound will be soluble in water. 13. Oil of turpentine, and other essential oils, dissolve a considerable proportion of sulphur when hot, the great- est part of which is deposited in crystals when cooled slow by. 14. The fat oils unite with sulphur by boiling, and acquire a deep yellowish brown colour; and a strong fetid odour 34 INTRODUCTION 15. Sulphur combines with chlorine forming a peculiar compound called chloride of sulphur, having the follow- ing characteristics. It is a fluid appearing red by reflec- ted, and yellowish green by transmited light. Specific gravity 1. 7. In the air it fumes and emits a pecu- liar odour somewhat resembling sea weeds. Its taste is acrid, hot, acid and bitter. Water decomposes it, the- sulphur is precipitated, and the liquor is found to contaiii sulphuric and muriatic acids. When added to nitric acid a mutual decomposition takes place with violence, nitric oxide gas and chlorine are evolved and sulphuric acid is formed. Exp. This may be formed in the following manner. Pass a current of chlorine over flowers of sulphur, or having filled a retort with chlorine gas or oxymuriatic acid gas, heat flowers of sulphur in it until they sub- lime. 16. Sulphur unites with cyanogen, or prussine, form- ing a substance called sulpho-cyanic acid by some, by others sulphuretted chyazic acid. 17. The characteristics of this substance are. It is a colourless and transparent fluid, specific gravity 1.022, of a pungent smell like strong acetic acid. It combines with salefiable bases, and forms salts called sulpho-cyana- tes. They are soluble, deliquescent and crystallizable. According to Dr. Thomson, it is composed of 1 atom cy- anogen and 3 atoms sulphur. Exp. The following method has been adopted to ob- tain itw Three or four parts of prussian blue added in small quantities at a time, are boiled in a solution of one part of sulphuret of potash in water; a transparent, col- ourless and neutral liquid is obtained, to which after be- ing fiitercd, sulphuric acid must be added, in sufficient quantities to give it decidedly acid properties. The TO CHEMISTRY. tf0 liquid is kept for a short time at a temperature near a boiling point, and afterwards allowed to cool. On the addition of a little finely pulverized oxide of manganese, the solution acquires a fine crimson colour, and after fil- tration it is decomposed by pouring into it two parts of sulphate of copper, and three parts sulphate of iron in water, until the crimson colour disappears, a white pre- cipitate, composed of sulpho cyanic acid, and oxide of copper is formed; the former of which is transferred to potash when boiled in the solution. To the filtered li- quid is added sulphuric acid in excess, and by subsequent distillation the sulpho-cyanic acid passes over into the receiver, mixed with a little sulphur and sulphuric acid~ from which it may be freed by saturating the liquid with carbonate of barytes. 18. Sulphur unites with phosphorus, and when com- bined may be made to contain various proportions of its elements, and Exhibit different phenomena. The com- pounds are exceedingly inflammable and more fusible than either of their elements. Exp. 1 proportion of phosphorus and 3 of sulphur, congeal at 100° F. 2 of phosphorus and 1.5 of sulphur remain liquid at 40°; and 8 of phosphorus and 1 of sul- phur at 68° F. 19. Sulphur combines with carbon forming a com- pound long known by the name of alcohol of° sulphur, possessing the following properties. Its taste pungent and disagreeable; smell stronger than sulphuretted hy- drogen. It boils at the temperature of 110 to 115°. The elasticity of its vapour at 55° is such as to support 7 25 inches of mercury. Water at the same temperature supports 4.3 ; alcohol 1.23, and ether 11 inches. By evap- oration it produces a greater degree of cold than ether. R may be cooled down to 50° without freezing; it readi- f»8 INTRODUCTION ly dissolves sulphur, but if to the solution be added ether or alcohol, the excess of sulphur is precipitated, and the two liquids combine. Exp. It may be obtained by subliming sulphur through ignited charcoal in a porcelain tube. The first product is a liquid of a yellowish colour, which colour is owing to the presence of a-little sulphur. By distillation in a glass retort, a colourless product is obtained which is the pure sulphuret of carbon. 20. Sulphur is applied to many important uses. It \s employed in medicine, it enters into the composition of sulphuric acid, of gun powder, and of the common com- position for paying the bottom of ships. Its fumes are employed in bleaching of silk and wool, and checking the progress of vinous fermentation. Common matches, for lighting fires are tipped with sulphur. PRACTICAL QUESTIONS. In what state is sulphur found ? What is the mineral combination called ? Does sulphur exist in any other substance but mine- rals? How is sulphur obtained ? What are the characteristics of sulphur ? What is its specific gravity ? What is the effect when sulphur is kept melted for some time in an open vessel ? What are flowers of sulphur ? Illustrate this by experiment. When sulphur combines with oxygen in combustion, what is the compound ? What experiment illustrates this ? Explain the process. TO CHEMISTRY. 97 How many proportions of oxygen is sulphur capable of combining ? How would you form sulphuric acid ? Is sulphur a simple substance ? How is this proved ? With what does sulphur combine 1 Illustrate this by experiment. Can sulphur be dissolved in essential oils ? What effect do fat oils produce on sulphur 2 What is chloride of sulphur ? How do you form it ? What is sulpho-cyanic acid ? Relate the method for procuring it. What is sulphuretted phosphorus ? What phenomena do the different proportions of sul- phur exhibit ? What are the characteristics of sulphuretted carbon ? How can it be obtained ? What are the uses of sulphur ? CHAP. X. Of Phosphorus. I. Phosphorus is a substance which exists in many animal and some vegetable substances, and may be ob- tained by decomposing the bones of animals. 2. It is never found in its simple state, but always in combination, from which it cannot be separated but by a chemical process. 3. Its characteristics are. It is semi-transparent, solid, slightly brilliant, and of the consistence of wax. Specific 9 9G INTRODUCTION gravity 1.7 7. Taste somewhat acrid and disagreeable, smell resembling in some measure garlic. 4. It is brittle under 32°, fracture vitreous, brilliant and sometimes lamellated. 5. Above 32°, it softens a little, at 90° it becomes ductile, melts at 99°, becoming transparent like a white oil at 180° begins to be vaporized, and boils at 650. 6. It is highly inflammable, when heated in the air it takes fire at the temperature of 118° and burns with a very bright flame, emitting a large quantity of vapour or smoke. Exp. 1. If a small bit of phosphorus be put upon the outside of a Florence flask, and hot water be put into the flask, the phosphorus will immediately take fire and ex- hibit a beautiful appearance. Exp. 2. Put 30 grains of phosphorus into a Florence flask with four ounces of water; cause the liquor to boil over a lamp, balls of fire will soon be seen to issue through the water, after the manner of an artificial fire work, attended with the most beautiful corruscations. Exp. 3. Rub cotton in pulverized rosin, and wrap it round a small piece of phosphorus, then place the whole under the receiver of an air pump, after exhausting the receiver, the cotton will take fire and display a very beautiful appearance on the admission of the air. Exp. 4. Take a bit of phosphorus about the bigness of a large pin's head, and having wiped it upon blotting paper, put it into the middle of a piece of dry cotton, strike it with a hammer and it will inflame. 7. Phosphorus in combustion in oxygen gas, absorbs it and consumes nearly once and a half its own weight, and phosphoric acid is produced equal in weight to the oxygen and phosphorus consumed. Exp. 1. Attach a bit of phosphorus to a small spoon TO CHEMISTRY. ^9 produces the most brilliant white light imaginable . concrete white flakes adhere to the sides of the receiver which will be found to be phosphoric acid. 8. Its combustion in oxygen gas furnishes results different from all other combinations, viz. phosphoric and phosphorous acids or oxide of phosphorus. Exp. Into a retort that will hold about a pint, put half a pint of water, and then add a small bit of phosphorus, place it over a lamp and when it gets warm, stars of fire resembling sky rockets will be seen shooting about the water in a most beautiful manner, and adhering to the sides of the retort. If the lamp is withdrawn when the water boils, a curious appearance resembling the aurora boreulis, is seen at the surface of the water. If the heat be continued, a stream of light is seen to issue from the mouth of the retort, which returns into the retort when taken away. 9. Phosphorus combines with oxygen at a lower temperature than most other substances, whence its great attractive power for this principle ; hence the facil- ity with which it takes fire. Exp. Put a piece of phosphorus into a quill and write with it on the wall of a dark room ; the words thus writ- ten will appear as if brilliantly illuminated. It is by slow combustion, in consequence of the rapid absorption of oxygen, that the light is produced. 10. In open air phosphorus undergoes a slow combus- tion at 43° emitting light in the dark without the produc- tion of sensible heat, absorbing a portion of oxygen and producing phosphorous acid. Exp. Provide a glass funnel, place it in the mouth of a bottle, then take sticks of phosphorus enclosed in glass tubes to prevent their contact, and place them round the inside of the funnel. Put a little distilled water into the 100 INTRODUCTION receiver and suffer the apparatus thus arranged to re- main 21 hours, a quantity of phosphorous acid will be form el. Observation. It may at first appear singular that phos- phorus should burn at so low a temperature in atmos- pheric air, when heat must be applied for its combustion in oxygen gas But this circumstance seems to be owing to the nitrogen gas of the atmosphere. This gas dis- solves small particles of phosphorus, when in contact with it, which being thus minutely divided and diffused in the atmospheric air, combines with the oxygen and undergoes a slow combustion. The reason why the same effect does not take place in oxygen gas is, that oxygen is not capable of dissolving phosphorus. It is therefore necessary that heat should be applied to effect that division of the particles which in the last case is effected by nitrogen. 11. Phosphorus combines with sulphur and forms a compound, which takes fire in contact with atmospheric air. Observation. It is this composition which forms what is called phosphoric matches. Exp. Mix one part of flowers of sulphur with eight parts of phosphorus, and dip a splinter of pine wood into the mixture. Rub the end against a piece of cork or wood, and a flame will be immediately produced. 12. Phosphorus is soluble in fixed, essential oils, and ether. Exp. 1. Dissolve some phosphorus in sulphuric ether, this solution when poured in small quantities into hot water exhibits a beautiful appearance. 13. At the temperature of 70° F. phosphorus com- bines with oil, an 1 forms a compound, which in contact ^.ith atmospheric air becomes luminous in the dark TO CHEMISTRY. - 101 Exp. Put one part of phosphorus into six parts of good olive oil, or oil of cinnamon, which is preferable. Di- gest it in a gentle sand heat until the phosphorus is dis- solved, on which, immediately cork the bottle. If this oil be rubbed on any thing, it becomes luminous in the dark, and yet has not sufficient heat to burn the sub- stance. 11. Phosphorus combines with lime and forms a com- pound which has the singular property of decomposing water, by being thrown into it; which is owing to itsi absorbing oxygen from the water; called phosphuret of lime. Exp. Put half an ounce of phosphorus cut small into a glass tube about a foot in length, and half an inch in diameter, closed at one end and filled up with quicklime grossly pulverized, stop the tube loosely. Heat that part of the tube which contains the lime until it becomes red hot, and then apply the heat of a lamp to the part containing the phosphorus, which will sublime and mix with the lime. When thrown into water, a decomposi- tion takes place, phosphuretted hydrogen gas is evolved, and rises in bubbles to the surface where it immediately inflames. 15. Phosphorus combines with many of the metals and forms peculiar compounds ; with iron it forms what Smiths' call cold short. 16. Phosphorus is usually obtained from the phos- phoric acid which exists in the bones of animals. Exp. Calcine bones to whiteness in an open fire, and having pulverized them, put them into a stone ware pot pour gradually upon the powder diluted sulphuric acid, continually stirring the mixture, until it is reduced to the consistence of cream, after the powder has subsided, 9* i»2 INTRODUCTION pour off the clear liquor, reserving it, and add water, pour this to the former liquor, and throw the sediment on a filtre, then add hot water until it passes through the filtre, tasteless. This fluid must be gradually evaporated in a glass vessel to the consistence of syrup. It is then mixed with an equal weight of charcoal powder and sub- mitted to distillation in an iron or earthen retort. Instead of a receiver, the neck of the retort should be immersed in a vessel of water to a small depth, and the phosphorus as it comes over, will fall in drops to the bottom. It may be purified by a second distillation. PRACTICAL QUESTIONS. What is phosphorus ? Is it ever found in its simple state ? What are its characteristics ? What is*its state under 32° of temperature ? What is it above 32°. What is its appearance at the tempeifcture of 99° ? Illustrate this by an example. What are the phenomena of the combustion of phos- phorus in oxygen gas ? What are the results of the combustion ? At what temperature does phosphorus combine with oxygen ? What does phosphorus undergo in the open air ? How do you form phosphorous acid ? How do you explain the cause, that phosphorus in- flames spontaneously in atmospheric air, and not in oxy- gen gas ? What is the compound of phosphorus with sulphur 4 Is phosphorus soluble in oils ? To CHEMISTRY 103 At what temperature does phosphorus combine with oil, and what is the compound ? What is phosphuret of lime ? How do you prepare it ? Does phosphorus combine with metals ?. How is phosphorus prepared 1 CHAP. XI. Of Carbon. 1. Carbon is the base of the carbonic acid; in its greatest state of purity; it exists only in the diamond. 2. Charcoal in a state of purity, that is, unmixed with any foreign substance, is carbon. 3. Carbon forms a considerable portion of the solid matter of all organized bodies ; but it is most abundant in the vegetable creation, and it is principally obtained from wood. It is prepared by charring or burning in close vessels wood, which, when deprived of the water and oil, is charcoal. Exp. 1. Expose wood of any kind, stripped of its bark, to a red heat in a close vessel, till vapours cease to issue ; a black, opaque, shining, brittle substance will be obtained, which is charcoal. Pulverize this substance, and digest it in diluted muriatic acid, and afterwards ap- ply repeated affusions of cold water and then dry; it in a heat approaching to redness, it may be obtained suffi- ciently pure for general purposes. Common charcoal dried in the above heat, will answer for common pur- poses. 101 INTRODUCTION 4. The characteristics of good charcoal are. It is fixed in the fire, no heat being able to volatilize any con- siderable portion of it. It forcibly attracts and strongly retains a small quantity of water. Its antiseptic qualities are very great, .and for this purpose it is used in purify- ing and cleansing many foul and fetid substances. Illustration 1. It is employed in correcting the bad smell of corrupted water, of oiled silk bags, of ill condi- tioned ulcers, and for cleansing the teeth. 2. An excellent dentifrice may be prepared by pul- verizing together in a common mortar, a piece of char- coal, a lump of chalk, and a bit of gum-mirrh, and sifting it through muslin. Exp. Throw a quantity of well prepared charcoal in powder into water, which has been long kept, or which has become foul by, being in contact with putrid sub- stances, and the water will become perfectly sweet in the course of a few hours. Illustration 1. The properties of charcoal in resisting p.utrifaction, have suggested its application to casks con- taining water during long voyages. The inner surface of .the casks should be charred, when they are manufac- tured. 2, Piles or stakes driven into the ground, will last much longer, if they be charred m the same manner. 5... The most perfect carbon that can be prepared by art, contains about five per cent of hydrogen, 6. Well burnt charcoal is a conductor of electricity, though wood simply deprived of moisture by baking, is a non-conductor; but it is a very bad conductor of caloric. Observation. Sir H. Davy is of opinion, that if we could obtain carbon free from foreign ingredients, it would be metallic, in common with other metallic sub- stances. TO CHEMISTRY. 105 T. Diamond is carbon in a crystallized state ; but we are ignorant of the means which nature employs to crys- tallize it. 8. Diamond is combustible, and it is in consequence of this property, that its chemical nature has been ascer- tained. Illustration. Apply a degree of heat excited by the blow pipe and a stream of oxygen gas, the product will be pure carbonic acid. Exp. Charcoal will answer instead of diamond. Pro- cure some oxygen gas, having made the charcoal red hot, place it on a dish and introduce it into the jar. It will bura with great brilliancy. When combustion ceas- es, pour into the glass a small portion of tincture of lit- mus, and it will be converted to a red, intimating the formation of an acid during the combustion of the char- coal. If newly made lime water be poured into the jar,. a pellicle will immediately form on the surface of the water, which is a proof that the jar contains carbonic acid. 9. Carbonic acid is not a condensible vapour, but a permanently elastic fluid, which always remains in the state of gas under any temperature and pressure ; it was formerly called fixed air. 10. Loss light and heat are given out during the com- bustion of carbon in oxygen gas, than in that of most oth-rr substances ; because the oxygen, instead of enter- ing into a solid or liquid combination, is employed in forming another elastic fluid ; it therefore parts with less caloric. 11. If we take mto consideration the quantity of oxy- gen that carbon absorbs during combustion, and observe the proportion which the caloric bears to it, we may as- certain the degree of solidity in which oxygen is com- bined with it iOO IN I REDUCTION 12. Carbonic acid has a great tendency to combine with other substances ; the compounds are called carbo- nates. It is also combined with water. Illustration. It is this product which gives the agreea- ble zest to beverages, which are the results of fermen- tation; bottled cider and beer, and champaign owe their grateful taste to the diffusion of carbonic acid. It con- tains all the antiseptic properties of its base, carbon ; hence the great importance of it in putrid diseases. 13. Carbonic acid united with lime, forms chalk, mar- ble, and most of the stones used in making lime. 14. It is nearly twice as-heavy, bulk for bulk, as at- mospheric air; and where it exists in the atmosphere, Occupies a space nearest the surface of the earth. Illustration. Hence the reason, why dogs and other small animals are suffocated in caves, containing this gas, while man may walk upright with impunity. Exp. Balance a large funnel of paper in a pair qf scales, and pour carbonic acid into it from a spout of a jar, when that end of the balance will descend ; this shews that it is heavier than atmospheric air. 15. Carbonic acid does not support respiration nor combustion. Exp. 1. Fill a jar with carbonic acid gas, and put into it a mouse, the animal will be instantly suffocated. 2. Pour, the gas from a bottle on a lighted candle, it will be instantly extinguished, as though water had been poured upon it. 16. When plants are made to grow in carbonic acid gas, they absorb the base of the acid, a decomposition takes place, and pure oxygen is evolved. 17. Carbonic acid gas precipitates lime combined with water, and ^s an excellent test to discover the pre- sence of lime in that fluid. TO CHKM1STI.Y. ]07 Exp. Having prepared some lime water, breath into it from a pipe, and a pellicle will immediately be form* ed on the surface of the water, which is, carbonate of lime. 18. Carbon may be converted into a gr.s by uniting with a smaller proportion of oxygen than is sufficient to form the carbonic acid gas; it is called carbonic oxide, or gaseous oxide of carbon. 19. Carbon is capable of decomposing water, when heated to redness, it then separates oxygen from hydro- gen. Illustration. A small quantity of water thrown on a red hot fire will increase the heat ; for the coals or wood decompose the water, and thus supply the fire, both with oxygen and hydrogen gases. Exp. Substitute a porcelain tube, containing charcoal, in place of the gun barrel, plate 3, fig. 1. A lamp being placed under the retort, containing water, is caused to boil, the vapour is gradually conveyed through the red hot charcoal, by which it is decomposed, and the hydro- gen gas which^results from the decomposition, is collect- ed in the receiver. This gas is not pure hydrogen, but is combined with a small portion of carbonic acid, which gives it peculiar properties; it is known by the name of carbonated hydrogen gas. It obtains the carbonic acid from the union of the oxygen with the carbon. 20. Carbon is frequently combined with hydrogen in a state of solidity, as in coals, which owe their combusti- bility to those two principles. Illustration. The flame of coals is produced in conse- quence of the carburetted hydrogen which they contain; when this gas is consumed, the carbon continues to burn without flame. 108 TNTR0DUCT10S 21. Carbon is a non-conductor of heat ; charcoal is therefore used in the construction of refrigerators, for keeping liquors and other substances cool in warm weath- er, and likewise for coating furnaces and other chemical apparatus. 22. Plumbago, commonly called black lead, is a com- bination of iron with carbon, and contains about five per cent of iron. This substance is called carburet of iron, and approaches as near the diamond as any other sub- stance known. 23. Steel is a combination of iron with carbon ; the combination of carbon varies in different species, in all it is very small, amounting from 180 to 140 parts by weight. 24. The essential constituent principles of oils and fat, both vegetable and animal, are carbon and hydrogen; the difference of their appearance arises from the differ- ent proportions of these substances, and from other in- gredients, that are not chemically combined with them. 25. The difference of fixed oils and essential, or volatile oils, consists in the various proportions of carbon and hy- drogen. The essential oils contain nearer proportions of carbon and hydrogen, and are volatilized or evaporat- ed without being decomposed; whereas fixed oils cannot be without a decomposition. 26. The facility with which oil burns is owing to the combustibility of its constituents. 27. The difference between wax and tallow is prin- cipally owing to the degree of the purity of the com- pound ; both have the same essential ingredients; but tallow contains animal matter. 28. The combustion of a candle and lamp, both pro" duce carbonic acid gas and water. TO CHEMISTRY. 109 Illustration. In this case, the fixed oil is decomposed as the combustion proceeds, the carbon unites with a por- tion of oxygen from the atmosphere, and carbonic acid gas is formed; whilst the hydrogen combines with anoth- er portion of oxygen, and water is produced. 29. Carbon and hydrogen acidified by oxygen, form the constituents of all vegetable acids; likewise gum, starch, sugar are composed of these ingredients, and are called by some chemists, vegetable oxides. 30. In chemical operations, carbon is of essential ser- vice, by combining with the oxygen, from the very great affinity which it has for that substance. Illustration. Many of the metallic oxides are deoxy- genated, or restored to their metallic state, by mixing them with charcoal. Exp. Take red lead, tritoxide, which is lead in the third state of oxidizement, and mix it with a quantity of powdered charcoal in a crucible ; subject it to heat in a furnace for about an hour, then suffer it to cool, and a small button of metallic lead will be found at the bottom of the crucible. PRACTICAL QUESTIONS. What is carbon ? What is charcoal 1 How is carbon or charcoal obtained ? What are the characteristics of good charcoal ? How do you illustrate this ? What does the most perfect carbon, that can be pm pared, contain ? Is charcoal a conductor of electricity ? What is Sir H. Davy's opinion on this subject ? What is diamond ? How has its chemical nature been ascertained ? 10 110 INTRODUCTION Illustrate this by experiment. What is carbonic acid ? Why is it that less light and heat are given out during the combustion of carbon in oxygen gas, than that of any other substance ? How can we ascertain the degree of solidity in which oxygen is combined with carbon, during combustion ? What are carbonates ? What gives the agreeable zest to beverages ? What is chalk and marble ? How heavy is carbonic acid gas ? What is the reason that small animals are suffocated in caves ? Does carbonic acid gas support combustion and respi- ration ? Illustrate it by experiment. What effect do growing plants have on carbonic acid ? What effect does it have on lime water ? Illustrate it by experiment. What is carbonic oxide ? Can water be decomposed with carbon ? In what manner ? What is the gas formed ? Can carbon be combined with hydrogen in a state of solidity ? Illustrate it. Why is charcoal used in refrigerators, and in coating furnaces ? What is plumbago ? What is steel ? What are the constituents of oil and fat ? What causes the difference in their consistence ? What causes the difference between fixed and essential -oils ? ro CHE.V1STRY. 1 J J To what is the facility with which oil burns owing ? To what is the difference between wax and tallow ow- ing ? What does the combustion of a candle and lamp pro- duce ? Illustrate this. What forms the constituents of all vegetable acids ? What are vegetable oxides ? What use is carbon in chemical operations ? Illustrate this CHAP. XII. Of Alkalies. 1. Alkalies are a class of bodies distinguished by the following properties. They impress the tongue with a peculiar acid taste, which has been termed caustic or urinous ; a sensation commonly considered as contrary to sour. They have a strong affinity for water, with which they combine with great rapidity, and in great quantity. They change blue vegetable colours to green, the brown to yellow, and the yellow to orange. They corrode and dissolve animal substances. They unite with the oils and fats, and form compounds called soaps. They combine with many chemical agents, particularly the acids; with which they form the neutral salts. They are capable of being fused and volatilized by heat. Observation. Some of the above properties are dis- covered in two or three of the earths; barytes and stron- tian have been considered as alkalies by Vauquelin and Fourcroy, and some other French chemists. But this 112 INTRODUCTION arrangement has not been very generally received ; be- cause, as has been observed, if we admit these amongst the alkalies, there is hardly any good reason for exclud- ing lime, magnesia, and some other of the earthy sub- stances ; and because the greater solubility and fusibility of the alkalies sufficiently distinguish them from all these substances, which have also properties common to them- selves. 2. The cause of alkalies being caustic, is the strong affinity which they possess for the constituents of animal matter. In their pure state, they have a powerful at- traction for water, hydrogen and carbon, which are the constituent principles of oil, and it is principally by ab- sorbing these substances from animal matter, that they effect its decomposition; for when diluted with a suffi- cient quantity of water, they lose their causticity. Illustration. Caustic potash in solution is unfit for washing, but when incorporated with oil, it forms the well known substance called soap, which is universally used as a mild and excellent cleanser of the hands and face. 3. Whenever acids are in contact with alkalies or al- kaline earths, they unite with avidity and form compounds totally different in their properties from either ©f the constituents ; these bodies are called neutral or compound salts. Exp. To aqua fortis add carbonate of ammonia, (sal volatile) to the point of saturation; that is, until all effer- vescence ceases, or until fixed air ceases to be disengag- ed ; the acid loses its acidity, and the ammonia its pun- gency. 4. The alkalies are divided into two kinds, fixed and volatile. TO CHEMISTRY. 113 5. The fixed are those which do not evaporate on exposure to the air ; these are potash, soda and lithia. Note.—There are a number of newly discovered vege- table alkalies, which will be treated of in the vegetable department. 6. The volatile alkali evaporates on exposure to the air, in the form of gas ; this is ammonia. It contains no oxygen. 7. Potash derived its name from the pets, in which the vegetables from which it is obtained, used formerly to be burnt; the alkali remained mixed with ashes at the bottom, and was thence called potash. 8. It exists in nature in a great variety of forms and combinations, but is never found in a state of purity; it is combined with carbonic acid, with which it exists in every part of the vegetable kingdom, and is most com- monly obtained from the ashes of vegetables, which is the residue when all the other parts are volatilized by combustion. 9. Potash is obtained in the arts from wood ashes by lixiviation and evaporation. 10. Potash, as prepared in the manufactory, contains water, which is not easily separated by heat; 100 parts usually contain about 17 parts of water. It may, there- fore, properly be called an hydrate of potash. 11. Potash deliquesces or becomes liquid in the air, in consequence of its strong affinity for aqueous vapour. 12. It dissolves in one half its weight of water at 58°, and during the solution, heat is evolved. Exp. Take a small quantity of potash in a phial, and holding it in one hand, add to it a little water, as the so- lution goes on, a sensible warmth is communicated to the hand. 10* 114 INTRODUCTION Illustration. This phenomenon may probably be ac- counted for, by supposing that a solution of potash in wa- ter has a less capacity for heat than either of them in a separate state. 13. The specific gravity of pure potash, 1.7. 14. A perfectly pure solution of potash will remain transparent, on the addition of lime water ; shew no ef- fervescence with dilute sulphuric acid, and do not give any precipitate on blowing air from the lungs through it b}r means of a tube. 15. Potash in its caustic state is often used by sur- geons, under the name of potential cautery, to open ab- cesses and destroy excrescences. And it was formerly us- ed in medicine, diluted with broths, in cases of stone and gravel. 16. In an intense heat, it becomes greenish and may be vaporized, but is perfectly incombustible. 17. It may be crystallized into long compressed, quadrangular prisms, truncated by sharp pyramids. 18. It combines with carbonic acid, forming a sub- stance called pearl ash, in commerce ; and when purifi- ed, salt of tartar. Exp. Heat common potash to redness in a reverbe- rating furnace, many of the impurities will be driven off, and it becomes much whiter than before ; when cool, it will be found to contain carbonic acid, and is properly a sub carbonate of potash, or potash not fully saturated with carbonic acid. 19. Potash is sometimes employed to produce a frig- orific naixture, or artificial cold. Exp. . Mix quickly four parts of caustic potash in powder, undone of fine light snow in flakes, it will be- come liquid, and in the act of liquefying, a large quantity of caloric is absorbed ; of course, cold is produced. TO CHEMISTRY I \o 20. Potash converts all animal matter into a sapona- ceous jelly, in consequence of its attraction for water and oil. Exp. Take caustic potash and olive oil, of each equal parts, having dissolved the potash in its own weight of water, add the oil and agitate it for a few moments, a saponaceous compound will be formed, which is per- fectly miscible with water. 21. Potash fused with silex, forms glass ; silex is com- posed of sand and flint, it is infusible by itself, but when mixed with potash, it melts, when exposed to the heat of a furnace, combines with the alkali and runs into glass, which differs in its properties according to the proportions used, the quality of the ingredients and the manner of conducting the process. Exp. Fuse three or four parts of potash with one part of silex in a crucible, the result will be a soft brittle kind of glass, which is soluble in water; this solution is called siliceous potash, or liquor of flints. 22. Potash readily unites with sulphur, and forms the compound called sulphuret of potash, formerly liver of sulphur. Exp. Melt two parts of potash and one of sulphur to- gether, in a crucible, a liver brown substance will be ob- tained. 23. Potash is obtained not only from vegetables, but it is found on the surface of the earth, mixed with vari- ous minerals, especially with earths and stones, whence it is supposed to be conveyed into the vegetables by the roots of the plants. It is also met with, though in very small quantities, in some animal substances. 21. Potash changes the colour of blue vegetable in- fusions to a green. 116 rNTRt)DLCTIOH Exp. Put into a wine glass a small quantity of tincture of red cabbage, which is of a blue colour, add to it a few drops of the solution of caustic potash, and a dark sea green colour will be produced. 25. Potash combines with all the acids, some of which are of essential service in the arts, such as its combination with nitric acid, called salt petre ; with oxy- muriatic acid, £c. It likewise combines with phospho* rus, sulphuretted hydrogen, and earths ; it is used as a reagent in analysis, and it is the basis of all soft soaps. 26. Potash may be considered as the hydrated deut- oxide of potassium. OF SODA. 27. Soda is the basis of sea salt, or that used for cu- linary purposes, which is muriate of soda. 28. Soda has been known by the name of mineral al- kali, and is found in various parts of the earth ; in min- erals, sea water, and many lakes and springs. When thus found, it is called natron. 29. Soda may be obtained from common salt, but the best and usual way of obtaining it in Europe is by the combustion of marine plants, from the ashes of which it is produced in a manner similar to that for potash. It is likewise obtained by the decomposition of sulphate of soda. 30. It derives its name from a plant called sal sola soda ; by the Arabians, kali, the ashes of which affords it in great abundance. 31. Soda in taste, action on vegetable colours, oils and animal matter, resembles potash, but its specific gravity is not so great 32. When exposed to heat, it melts below ignition, and in the state of an hydrate, has the appearance of effervescence. TO CHEMISTRY. 117 33. It is a non conductor of electricity. 34. Soda has so great an affinity for water that it cannot be obtained free from it but at a very high tem- perature, what is commonly called pure soda contains 23 per cent of water. Exp. To prepare pure soda, proceed as follows. Dis- solve any quantity of carbonate of soda in twice its weight of boiling water, and add to the solution while hot, an equal weight of quicklime, mixed with water to a thin paste. Boil the mixture in an iron vessel, adding as much water as is necessary to reduce the mass to the- consistence of cream; boil and stir it for one hour. Then separate the liquid alkali either by filtration or subsidence, and boil it to dryness in a silver dish. Pour on the dry mass as much pure alcohol as is necessary to dissolve it. Put the solution into a phial until the insol- uble part has subsided, then decant the clear liquor and distil off the alcohol. Evaporate what remains in the retort to dryness, fuse it in a silver crucible, and pour it into a silver dish. When cool, break the mass into small pieces and preserve them in a phial closely stop- ped. 35. Soda thus prepared will be of a greenish white colour, of a urinous taste and great causticity, acting with great violence on animal matter. Water when thrown upon it is absorbed with great violence, and much heat is evolved accompanied with an alkaline smell. 36. Potash and soda are used for the same purposes in the arts, such as in the manufacture of glass, soaps, &c. OF LITHION OR LITHIA. 37. Lithia is a substance discovered in 1818, in some minerals in Sweden, and has been classed with the fixed alkalies. 118 INTRODUCTION Observation. It was first discovered in the mineral called Pctalite, in the proportion of 3 per cent, afterwards in the Lepidolite, in the proportion of about 4 per cent; and* in the Triphane or Spodomene, in the proportion of 8 per cent. 38. It is readily obtained by fusing the mineral with potash, dissolving the whole in muriatic acid evapora- ting to dryness, and digesting in alcohol. The muriate of lithia being soluble, is taken up while the other salts re- main, and by a second evaporation and solution it will be procured in a pure state. 39. Lithia differs from potash and soda. 1. By the fusibility of its salts. 2. By the great deliquescent prop- erty of its chloride, or the compound of lithia and chlo- rine. 3. By the comparative insolubility of its carbo- nate. 4. By its great capacity for acids, by which it sur- passes magnesia. 40. Lithia is found to contain a metallic base analo- gous to potassium and sodium, and may be obtained in the same manner. This has been called Lithium. 41. Lithia unites with sulphur. Sulphuret of Lithia has a yellow colour, dissolves readily in water, and is de- composed by acids in the same way as the other alkaline sulphurets. 42. Phosphorus decomposes water with the help of caustic lithia. Exp. Heat in a retort, phosphorus, with a solution of caustic lithia in water, phosphuretted hydrogen gas is disengaged which takes fire when it comes in contact with the air. 43. Lithia dissolves only in small quantities in alco- hol of specific gravity 0.85. When weak alcohol is ad- ded to an aqueous solution of lithia in a well stopped phial, no change takes place at first, but after some 10'CHEMISTRY. \\[, hours, the lithia precipitates in the form of a white powder. 44. Caustic lithia appear- not to be much more solu- ble in hot than cold water. Heat is evolved during its solution in water. OF AMMONIA. 45. Ammonia is the name given to n substance for- merly called volatile alkali. 46. This substance is distinguished from the fixed al- kalies by its comparative volatility, which is such that in common temperatures it can be retained in its liquid state only, by hs combination with water. Observation. This substance was unknown to the an- cients ; that which they called ammonia or volatile alka- li, was ammonia combined with muriatic acid. 47. Ammonia is caustic butdoes^not corrode ani- mal matter like .potash and soda. 48. Its most simple state is that of ammoniacal gas or vapour, which is lighter than atmospheric air, but not so light as hydrogen gas. Exp. To procure ammoniacal gas, mix one ounce of powdered sal ammoniac with two ounces of quick lime, put the mixture into a common flask, and apply a light- ed lamp or candle to the bottom, ammoniacal gas will rise in abundance. > Illustration. Sal ammoniac is composed of ammonia and muriatic acid, in this experiment a decomposition takes place, the muriatic acid quits the ammonia and unites with the lime, for which it has a stronger affinity than for the ammonia ; and ammoniacal gas is evol- ved. 49. All animal and vegetable substances disengage ammonia when in a 6tate of putrefaction. 120 'INTRODUCTION « 50. It is procured in the large way, by distilling of bum ing bones, horns, and other animal substances, hence sal Ammoniac has been called hartshorn. It was thought formerly, that this substance existed only in the horns of the Deer and Stag. 51. Ammoniacal gas has so strong a tendency to unite with water that it cannot be procured in the usual way, over water, in a pneumatic trough, because it would be absorbed by the water, but in order to collect it, a mer- curial bath is used. 52. Water impregnated with this gas is called harts- horn, commonly, when spirit is used instead of water, spirit of hartshorn, it is the ammoniacal gas issuing from water or spirit, that' causes the pungent smell, for if a phial containing it be left uncorked, the water soon be- comes inodorous. 53. Water diminishes in density by being impregna- ted with ammoniacal gas; and this augmentation of bulk increases its capacity for caloric. 54. By incorporating with water, the ammoniacal gas is liquefied and gives out its latent caloric. The conden- sation of the gas more than counterbalances the expan- sion of the water. 55. Ammoniacal gas mixed with ice or snow produces cold. Illustration. In this case the water or melted ice is rarefied by the impregnation of the gas, heat of course is absorbed, and cold is produced. 66. Ammonia in the state of vapour combines with sulphur and hydroguretted sulphuret of ammonia is pro- duced. Exp. To form this substance, distil a mixture of five parts of sal ammoniac, five parts of Sulphur, and six of quick lime together. 57. Ammoniacal gas unites with muriatic acid gasj TO CHEMISTRY. Jgj forms the substance called muriate of ammonia, or sal ammoniac. Exp. Into a small retort put a mixture of two parts of quicklime, and one of sal ammoniac, both in powder ; apply tjie heat of a lamp, and having collected the gas into a large receiver, convey into it some muriatic gas ; from these two invisible gases, a solid substance will be obtained in small white flakes. 58. Ammonia is considered as composed of three vol- umes of hydrogen and one volume of nitrogen condensed into two volumes, 59. Its specific gravity compared with that of com- mon air is 0.590; 100 cubic inches at a mean tempera- ture and pressure weigh 18 grains ^ and the weight of its atom is 21.25; that of oxygen being considered as 10. PRACTICAL QUESTIONS. What are alkalies, and how are they distinguished ? Do the earths possess any of these properties ? What is the cause of alkalies being caustic ? How is caustic potash rendered useful for washing ? What is the effect of the union of acids and alkalies 9 How are the alkalies divided ? What are they ? Why was potash so named? Where is it found ? HoW is potash prepared ? What effect does the air have on caustic potash ? What quantity of water will dissolve it ? Why is heat evolved in dissolving it? What is its specific gravity ? What are the properties of a pure solution of caustic potash ? Under what name do surgeons use it ? H 122 INTRODUCTION What appearance does it assume in an intense heat ? Can it be crystallized.? What is pearl ash ? Illustrate it. Is potash ever employed in freezing-mixtures? Illustrate this by an example. What effect does potash have on all animal matter ? What forms glass ? Does potash unite with sulphur? Is potash found any where but in vegetables ? What effect has potash on blue vegetable colours I Illustrate it by experiment With what does potash combine ? What may potash be considered to be ? What is soda ? Where is it found ? How may soda be obtained? What are the properties of soda? What effect has heat on this substance ? Has it any affinity for water? How do you prepare pure soda? What will be the properties of soda thus prepared ? What is Lithia ? In what was it first discovered 1 How is it obtained ? How does lithia differ from potash and soda ? What is the base of lithia called? Does lithia unite with sulphur ? What effect has phosphorus on water when united with caustic lithia ? Does lithia dissolve in alcohol ? Is lithia more soluble in hot than cold water? Is he it evolved during the solution? What is Ammonia ? TO CHEMISTRY. 123 How is it distinguished from the fixed alkalies ? Does ammonia corrode animal substances? In what form is its most simple state ? How do you procure ammonical gas ? Explain this proxess. When do animal substances disengage ammonia ? How is ammonia manufactured ? Why cannot ammoniacal gas be produced in the usual way ? What are water and spirit impregnated with this gas called ? What efl'ect does it have on water ? What is the theory of its producing heat in combining with water? What does it produce when mixed with ice and snow? Why? Does ammonia combine with sulphur? How is sal ammoniac formed ? Illustrate this by an experiment ? Of what is ammonia composed ? What is its specific gravity ? CHAP. XIII. Of the decomposition of the Alkalies and Earths. 1. When Sir H. Davy first turned his attention to the agency of the voltaic battery, he tried its power on a variety of compound bodies, and gradually brought to light a number of new and interesting facts, which led the way to more important discoveries. The facility with which compound bodies yielded to- voltaic e'.ectricity ir> 124 INTRODUCTION duced him to make trial of its effects on substances hith- erto considered as simple, but which he suspected of be- ing compound, and his researches were soon crowned with the most complete success. 2. The body which he first submitted to the voltaic battery, and which had never yet been decomposed, was potash. This substance gave out an elastic fluid at the positive wire of the galvanic apparatus, and at the nega- tive wire small globules of a very bright metallic lustre, resembling in appearance mcrcurj'. Thus proving that potash which had hitherto been considered as a simple incombustible body, was in fact a metallic oxide, and that its incombustibility proceeds from its being combin- ed with oxygen. Observation. The wires used in the experiment must be platina, for if iron were used, the oxygen would have combined with the wires instead of appearing in the form of gas. 3. The base of potash is called^otamwn, and in order to preserve it, it must be immersed in naptha. 4. The properties of potassium are. It is brittle and crystallized in its section. It is lighter than water. Specifie gravity between 8 and 9 ; water being 10. It is very soft and easily moulded between the fingers. At the temperature of 150° it is perfectly fluid, very much resembling quicksilver. It is volatatilized in a heat a little below that of redness. It is perfectly opaque ; ex- posed to the air, it rapidly attracts oxygen, and becomes tarnished. It attracts oxygen much more rapidly from water than from air. When thrown upon water, it acts with great violence, the water is found to be alka- line, and to contain potash. Exp. Throw a piece of potassium about the size of a pin's head. ontL.- surface of water, it swims and burn? p-■_/ -r-a -i^- TO CUi-MiSTKl. 125 with a beautiful light, mixed with red and violet. 5. It burns spontaneously in chlorine with great bril- liancy and red light, and forms chloride of potassium. Exp. Drop a very small piece into a jar containing chlorine, it will immediately inflamo. 6. It inflames spontaneously in the vapour of iodine, and consumes with a violet coloured flame ; during the inflammation, it absorbs oxygen and sends off hydro- gen: 7. It is soluble in hydrogen gas, forming hydroguret of potassium, which becomes inflammable in atmospher- ic air. 8. When potassium is heated in nitrous oxide, it burns vividly and potash is formed. 9. It inflames spontaneously in nitric oxide and upon the surface of nitric acid, the products being nitric oxide and potash, the potash immediately combines with the undecompounded acid to form a nitrate. 10. Potassium and sulphur combine with great ener- gy when heated together, producing much heat and light and forming a sulphuret of potassium. 11. Sulphuret of potassium is of a grey colour, and appears to consist of 30 parts of sulphur and 70 of po- tassium. 12. Potassium combines readily with sodium in vari- ous proportions. A small quantity renders sodium very soft and brittle, at a common temperature potassium is ren- dered fluid and its specifiic gravity is considerably dimin- ished. 13. Potassium may be obtained by chemical means, without electricity. Exp. If turnings of iron be heated to whiteness in'a curved gun barrel, plate 4, fig. 1 and 2, and if melted potash be made slowly to come in contact with the turn- *11 126 INTRODUCTION ings, air being excluded, potassium will be formed and will collect in the cool part of the tube : it may likewise be produced, by igniting potash with charcoal. The above method of decomposition was invented by M. M. Gay Lussac and Thenard. Fig. 1, is a gun barrel bent somswhat in the form of the letter S. Before the curvatures are given to it, the internal surface must be cleaned by stopping one end, introducing into the other, diluted sulphuric or muriatic acid, and shaking the bar- rel, so that every part may be exposed to the action.— After the liquid is poured out, the barrel is to be well washed with water, dried by linen or bibulous paper, and stopped at both ends. The part which is to be exposed to heat from a. to b. is to be covered with a lute, which should be formed of fine clay and sifted sand, in the proportion of 1 to 5, thoroughly incorporated, and rendered 60 little plastic by the quantity of sand as to be applied with some diffi- culty. The lute should contain as little water as possi- ble. The thickness of the lute over the iron should be about -frfo of an inch. It should, after the application, be allowed to dry for a few days in the shade, and then in the rays of the sun or a gentle heat; after which, the rents, if there be any, should be filled with fresh lute.— The space from c. to a. should be filled with clean iron turnings, and the barrel is to be laid across a reverbera- tory furnace, fig. 2, having its internal diameter equal to about 11 1-2 inches; the barrel at a. supporting itself on the furnace, and at b. being supported on a piece of brick. The two openings through which the barrel passes, aie to be carefully closed with lute; which, on the inside, should consist of that which is the most infusi- ble. The cork is then to be drawn from e. and 3 1-2 to 4 1-2 ounces of fused potash in fragments are to be intro- TO CHEMISTRY. 127 duced into the barrel and pushed down to c. fig. 1. Thus the space from f. to c. will be filled with potash, while that from f. to e. will be empty. As there is a large quantity of gas extricated in this operation, and the other end of the tube is liable to be obstructed, a passage is given to the gas by fitting a curved glass tube into e. and causing its mouth to open into a vessel g. nearly filled with mercury, and supported on a stand. Fire is then to be lighted in the furnace, and when the flame appears at the dome, pieces of linen, moistened with water, are to be applied to the part containing the potash, to prevent it from melting; a recipient is to be adopted to the gun barrel at h. fig. 1. This consists of two pieces or tubes i. k. of copper, the mouth of the barrel being inserted into i. and the other extremity of i. embracing k. from which passes a curved tube that may be made to open under the" surface of mercury, as seen in fig. 2. The joinings of the tubes are to be luted. Then, by means of a double bellows, the heat in the furnace is to be raised as high as possi- ble ; when this is effected, a semi-cylindrical pan is to be suspended below the barrel, reaching from c. to a. The portion of the barrel from a. to e. fig. 1, is to be heated by live coals ; the potash contained in it will be melted and flow into that part which is intensely heated. A great quantity of hydrogen gas will be disengaged, and a portion of potassium will be formed and condensed at the extremity h. and in the recipient i. k. When the gas nearly ceases, another portion of the potash higher up in the barrel is to be heated; the gas will again come over, and these processes are to be repeated until the gas has been extricated from the whole. Care must be taken that too much potash should not be melted at one time, otherwise the temperature in the 128 INTRODUCTION first part of the barrel would be reduced too low to effect the decomposition of the potash ; hence the reason why the alkali is used in fragments and not in a single piece. The best sign that the experiment goes on well, is the rapid production of gas without the disengagement of very thick vapours at the extremity of the glass tube.— The duration of the experiment, from the time of the melting of the first portion of potash, should be more than an hour. When it is finished,, the tube at e. should be withdrawn from the mouth of the barrel, and that of the tube at I. be closed with lute. The barrel is withdrawn from the furnace and cooled by the affusion of cold water, which detaches the lute. In order to obtain the potassium which is condensed at k. and flows for the most part into the recipient i. k. the lute is removed at h. the mouth is closely stopped; a little oil of naptha is poured into the recipient, the two pieces are separated and the metal contained in them is made to fall into another portion of naptha. The potassium thus obtained, is commonly pure, and may be best preserved by giving it a spherical form and keeping it in naptha. By cutting off the barrel at b. and plunging the end in naptha, the potasssium in it may be obtained by introducing into it a cylindar of iron, nearly of the same diameter, and detaching it from the surface. It happens that, generally, only about half of the pot- ash is consumed in the experiment. The nature of the lute, and its application and drying, are circumstances which have an important influence upon the success of the experiment. If it do not con- tain sufficient sand, or if it be badly applied or dried, it either vitrifies and runs, or it falls off and exposes the iron to oxidizement and fusion. Several attempts have been made to simplify the above - TO CHEMISTRY. 129 process, and to substitute a more economical one. Pro- fessor Gorham succeeded in procuring very good potas- sium in the following manner. The lower part of a gun barrel properly closed, and about 16 inches in length, was luted ; a mixture of dry potash and clean iron filings was introduced into it ; a tube of copper was then placed in it, but out of reach of the strongest heat, and a glass tube was connected with the mouth and opened under oil of turpentine. Heat was applied until the lute and part of the barrel began to melt. On cooling it, 30 or 40 grains of good potassium were found condensed in the tube, and as much of an al- loy of iron and potassium in the barrel itself. He re- peated this experiment five times, in two of which, he was successful, and in three, unsuccessful.* 14. Sodium, the base of soda, is obtained in the same way as potassium, only a rather higher degree of heat is required. In appearance, it resembles silver; it is of great lustre, and is a conductor of electricity. 15. It is fusible at 200° F. 16. It is not volatilized at a heat that melts flint glass. 17. Its specific gravity is 0.97223, water being 1. 18. It absorbs oxygen from the atmosphere, and burns at an high temperature with bright sparks. 19. Sodium decomposes water with effervescence, and is inflamed in contact with nitric acid. 20. Sodium readily unites with phosphorus and sul- phur, and forms compounds, less inflammable than those with potassium. 21. When heated with oxygen or chlorine, it burns with great brilliancy. * Ooiham'i elements of chemical science, vol. ii. p. 516. 1-30 INTRODUCTION 22. Sodium combines with two proportions of oxygen The one is that which constitutes soda. The other is of a deep orange colour, it is formed by burning sodium in oxygen gas, an excess of the gas being present 23. The peroxide of sodium fuses at a much less heat than soda; if thrown into water, one proportion of oxy- gen escapes in the form of gas, leaving soda, which dis- solves in the water. 24. Sodium combines with many of the metals form- ing peculiar alloys. 26. When sodium is united with potassium in a small proportion, it forms an alloy which is more fusible than either of the metals. The compound is of less specific gravity, which is not common with other metallic al- loys ; and serves to prove that there is not a great affini- ty between the metals. 26, One part of sodium renders 40 of mercury solid at the common temperature of the atmosphere ; when these combine, heat is disengaged. 27. Alloys of the metals and sodium when exposed to the air, separate the sodium in consequence of its combi- nation with oxygen. 28. When potassium or sodium is heated in ammonia- cal gas, the metal becomes changed to an olive green colour, and loses its metallic lustre ; at the same time a portion of the gas is absorbed, and a quantity of hydro- gen is emitted exactly equal to the quantity that would be evolved, if the potassium or sodium were put into water. 29. If the olive green matter be heated, it gives out three-fifths of the ammonia absorbed, two-fifths in the state of ammoniacal gas, and one-fifth in the state of hy drogen gas and azote, to rin visTry. 131 30. If the olive coloured matter be placed in contact with a very little water, it is converted into potasli or soda and ammoniacal gas, and the gas is just equal to what the metal had absorbed. 31. If it be placed in contact with a metal and heal- ed, an alloy-of the metal with potassium or sodium is ob- tained. Observation. Dr. Thomson is of opinion, that these curious facts shew that potassium and sodium have the property of decomposing ammonia and combining with its azote, and the azoturet, or compound of sodium or po tassium, formed, combines with a portion of the unde- composed ammonia. The facN, however, best accord with the opinion that an unknown compound of azote and hydrogen unite with the alkaline metal, while the compound thus formed, combines with a portion of Undecomposed ammonia. 32. From analogy, it has been inferred by some chemists, that ammonia contains a metallic base combin- ed with oxygen, and many interesting experiments have been instituted to ascertain the fact; further discoveries are necessary in proof of the hypothesis. 33. Some of the earths in like manner have been de- composed and found to be oxides of metals. With these, metallic alloys have been formed with other metals. PRACTICAL QUESTIONS. How were the alkalies decomposed ? What was the first alkali tried, and what was the pro- cess ? Why could not iron wire be used in this experiment ? What is the base of potash called ? What are the properties of potassium ? How can you form chloride of potassium ? |;i2 INTRODUCTION What effect has the vapour of iodine upon it ? What effect has hydrogen gas in contact with it 1 What is it in nitrous oxide ? What in nitric oxide ? What phenomena do potassium and sulphur exhibit, when heated together? What are the constituents of sulphuret of potassium ? What are the combinations of potassium with sodium ? How can potassium be obtained without electricity ? Describe Gay Lussac's and Thenard's apparatus ? Will any hydrogen gas be disengaged ? How do you give a passage to the gas ? Is it essential to attend to the quantity of potash ? Why ? How do }'Ou know that the process goes on well ? How do you obtain the potassium, after the experi- ment ? How can it be preserved ? How much of the potash is consumed in this experi- ment ? Is there any alloy formed ? What should be the nature of the lute 2 Has this process been simplified ? Describe Professor Gorham's process ? How much good potassium did he obtain ? Was there any alloy ? How is sodium obtained ? At what temperature is it fusible ? When is it volatilized ? What is its specific gravity 1 Does it absorb oxygen from the atmosphere ? Does sodium unite with phosphorus and sulphur ? What is the effect, when heated with oxygen or chlo- rine? TO CHEMISTRY. 133 With how many proportions of oxygen does sodium ■combine, and what are their properties ? What are the phenomena attending the peroxide of chlorine ? Does sodium combine with any of the metals ? What is the compound of sodium with potassium ? What effect has sodium on mercury ? , What effect does the air have on alloys of metal, with todium ? What effect has ammoniacal gas on sodium and potas- sium? When the olive green matter is heated, what does it exhibit ? What, when placed in contact with water ? When placed in contact with a metal and heated, what does it exhibit ? What is the opinion of Dr. Thomson, on this subject ? How do chemists infer that ammonia has a metallic base ? Have the earths been decomposed ? CHAP. XIV. On the Earths. 1. The term earth in chemistry is applied to those bodies, which, until the 19th century, were all regarded as simple substances, and from the different combination of which, all those substances are formed, which are usually classed as earths and stones. 2. The number of substances classed under the name of earths, hitherto discovered, are ten, viz. 12 134 INTRODUCTION 1. Barytes, 4. Magnesia, 7. Glucina, 2. Strontian, 5. Alumina, 8. Zirconia, 3. Lime, 6. Yttria, or Ittria, 9. Silica, 10. Thorina. 3. From recent discoveries, some have been led to conclude, that all earths are metallic oxides; but this has not been ascertained. 4. Their properties are ; they do not combine with metals, but have an affinity for some of the metallic ox- ides. 5. They are divided by some chemists into two classes, viz. those which possess merely the characteristics of earths, which are insoluble in water or alcohol, or nearly so. When perfectly pure, they are in the.form of white powder, destitute of smell or taste, infusible, and unal- terable in the air. 6. The second class are those, which not only possess the above properties, but likewise those of an alkaline nature, having a strong taste, soluble, in some measure, in water and alcohol, and changing vegetable blues to green. 7. According to Sir H. Davy, the earths found in plants, are four, viz. silica, or the earth of flints ; alumi- na, or pure clay ; lime and magnesia. The lime is usu- ally combined with carbonic acid. 8. Lime and silica are much more common in the vegetable kingdom than magnesia ; and magnesia more than alumina. 9. The earths form a principal part of the matter of the ashes of plants, insoluble in water. The silica is distinguished by its insolubility in acids. The calcareous earth, unless the vegetable substance be very strongly ignited, dissolves with effervescence in muriatic acid.— \lnmuia is distinguished from the other earths, by being TO CHEMISTRY,. 135 acted upon very slowly by acids, and by forming salts very soluble in water, and difficult of crystallization. 10. It is on the principle of the incombustibility of earth, that its power of producing such an intense heat when mixed with other substances, arises, as in turf or peat, &c. II. Turf is composed of roots, grass, the remnants of animal and vegetable substances, together with alumina, lime, silex, and sometimes magnesia. 12. In combustion, it is not the earths that burns, but the vegetable and animal substances. The caloric which is produced by this combustion, causes the earth to be- come red hot, and this being a bad conductor of heat, re- tains its caloric a long time; but the earth does not ab- sorb oxygen or undergo any alteration in the fire. It is, however, an excellent radiator of heat, and owes its utility, when mixed with fuel, solely to that property. Illustration. On this principle, Count Rumford recom- mended balls of incombustible substances to be arranged in fire places, and mixed with the coals, by which means the caloric disengaged by combustion of the latter, is more perfectly radiated, and an expense of fuel is saved. 13. Precious stones are composed of a number of earths, sometimes salts, and even metals. 14. The earths are often found crystallized in pre- cious stones, which must have been a slow and regular work of ages. Illustration. To account for the slow and gradual crystallization of earths in precious stones, seeing they are almost insoluble in water, we may imagine, that when water holding in solution some particles of earth, filters through the crevices of hills and mountains, and at length, drops into some cavern, each successive drop may be slowly evaporated, leaving behind it the particle 136 I3TRODUCTION of earth which it held in solution. Crystallization i» more regular and perfect in proportion to the evapora- tion of the solvent; in this case, nature has an advantage over the artist; she carries on her operations unlimited by time, nor retarded in her gradual progress. 15. In examining the earths, we must take them as they are usually found in nature, and not when wrought or modified by art. OF BARYTES. 16. Barytes has its name from its weight; it is the heaviest of the earths. It is usually found in the state of a sulphate. 17. The characteristics of pure barytes are, great weight, strong alkaline properties, such as turning some blue vegetable colours to green, destroying animal sub- stances-, and shewing a powerful attraction for acids. 18. Its affinity for the sulphuric acid is so great, that it will always detect its presence in any substance or combination whatever, by immediately uniting with it and forming a sulphate. Exp. 1. Dissolve in a glass of water one grain of sulphate of soda, and add to it a few drops of nitrate of barytes in solution, white clouds will be immediately formed. Illustration. Barytes has a stronger affinity for sulphu- ric acid than any other bony, forming with it, in this in- stance, a sulphate of barytes, which is one of the most insoluble substances, and the soda unites with the water. This property of barytes renders it an excellent test for detecting the presence of any quantity, however small, of sulphuric acid. Exp. 2. To shew its alkaline properties on vegetable colours, tinge water with Brazil wood, by an addition ol TO CHEMISTRY. 137 a small quantity of a solution of barytes, the red will be changed to violet. Exp. 3. In a glass of distilled water, rendered slight- ly blue by the tincture of red cabbage, drop a few grains of the solution of barytes, the blue will be changed to green. 19. Barytes combines with sulphur, when they are mixed together and heated in a crucible. 20. Sulphuret of barytes is of a reddish yellow col- our, and when dry, without smell. When thrown into hot water, a powerful action takes place. The water is decomposed, and two new products are formed, viz. hy- dro-sulphuret, and hydroguretted sulphuret of barytes. The first, crystallizes as the liquor cools ; the second, remains in solution. 21. The hydro-sulphuret of barytes contains 9.7 of barytes, and 2.125 sulphuretted hydrogen. 22. The crystals are white scales, have a silky lus- tre, are soluble in water, and yield a solution having a greenish tinge. Taste acrid, sulphurous, and when mix- ed with the hydroguretted sulphuret, is corrosive. It rapidly attracts oxygen from the atmosphere, and is con- verted into sulphate of barytes. 23. The hydroguretted sulphuret is a compound of 9.70 barytes and 4.125 bisulphuretted hydrogen^ or hydro- gen with two proportions of sulphur ; it is contaminated with sulphite and hyposulphite in unknown proportions. 24. Barytes combines with phosphorus. It may be easily formed by exposing the constituents together, to heat in a glass tube. Their reciprocal action is so in- tense as to cause ignition. 25. Like phosphuret of lime, it decomposes water, and causes the disengagement of phosphuretted hydrogen 12* . 138 INTRODUCTION gas, which spontaneously inflames in contact with the air. 26. Barytes has been decomposed and found to con- tain a metallic base, called barium. It is of a dark grey colour, with a lustre inferior to that of cast iron. It is fusible at a red heat; its density is superior to that of sulphuric acid. When exposed to air, it instantly becomes covered with a crust of barytes, and when gentiy heated, burns with a deep red light. It effervesces violently in water, converting this liquid into a solution of barytes. 27. Barium combines with oxygen in two proportions, forming, 1st. barytes, and 2d. deutoxide of barium. 28. The salts of barytes are white, and more or less transparent. They are all poisonous except the sul- phate ; hence the counterpoison is the sulphuric acid diluted for the carbonate, and sulphate of soda, for the soluble salts of barytes. OF STRONTIAN. 29. Strontia or strontian is so named from a place in Scotland, where it was first discovered. 30. Pure strontian is of a greyish white colour, and a pungent acrid taste. Its specific gravity is nearly that of barytes, being about 1.6. It is soluble in 200 times its weight of water at 50°, but little more than six times its weight at 212°. On cooling, it deposits flat rhomboidal crystals. It is likewise soluble in small proportions in alcohol. Exposed to heat, these crystals undergo aque- ous fusion, and become dry ; in this dry state, it requires the heat of the oxyhydrogen blow pipe to fuse it. 31. Strontian differs from barytes in being infusible, but at a very intense temperature, much less soluble, of a different form, weaker in its affinities, and not poison- ous. Itshsaline compounds afford differences much more distinguishable. TO CHEMISTRY. 133 32. The basis of strontian is strontium. It is fixed, difficulty fusible, and not volatile. It is converted into strontian on exposure to the air, and when thrown into water, decomposes it with great violence, producing hy drogen gas and a solution of strontian. Strontian is con- sidered as composed of about 86 strontian +14 oxygen in 100 parts. 33. Strontian when mixed with inflammable substan- ces, causes a flame of a beautiful red colour. Exp. 1. Take 40 parts dry nitrate of strontian, 13 parts of finely powdered sulphur, 5 parts oxvmuriate of potash, (chlorate) and 4 of sulphuret of antimony. Pul- verize the oxymuriate of potash, and sulphuret of anti- mony separately in a mortar, and then mix them togeth- er on paper; after which, add them to the other ingre- dients, previously powdered and mixed. Rub them to- gether on paper, and a beautiful red flame of great bril- liancy will be produced. Exp. 2. Add a little of the solution of muriate of strontian to alcohol, kindle it, and red flames will be produced. Exp. 3. Sprinkle a little of powdered muriate of strontian on the flame of a candle, and the flame will as- sume a carmine colour. 31. Strontian is slightly caustic, acting feebly on an** mal matter. It differs from barytes, in being infusible, much less soluble, of a different form, weaker in its affin- ities, and not poisonous. OF LIME. 35. Lime is the oxide of calcium, a name given to the base of lime. It is generally combined with carbonic aeid in lime stone, marble and chalk, and is essential to the constitution of marles. 140 INTRODUCTION 36. When deprived of carbonic acid, it possesses a caustic and corrosive quality, and is called quick lime. Exp. Expose carbonate of lime to a strong heat in a crucible, carbonic acid and water is disengaged, and the result is quick lime. 37. Carbonate of lime loses by calcination 40 per cent of its weight 38. Pure lime has such an affinity for carbonic acid and water, that it cannot be preserved for any length of time but in glass vessels, closely stopped. 39. When water is added in small quantities to quick lime, the water is solidified, and heat is evolved. Exp. Pour a little water on a lump of quick lime? the water immediately disappears, and heat is produced. Illustration. The heat proceeds not from the limej but from the water, and is the latent which causes the liquidity of the water. 40. Lime requires nearly 700 times its weight of wa- ter for its solution ; in this state, it is called lime water.— When first made, it is perfectly clear and colourless ; but it soon attracts carbonic acid from the atmosphere, and a pellicle is formed on the surface. Exp. 1. Expose lime water fn a glass,' for a few min- utes, to the air, the lime separates from the water, and appears on the surface in the form of a white film, which is carbonate of lime or chalk. Exp. 2. Breathe into a glass of lime water, the car- bonic acid which is mixed with the air expired, will separate the lime as in the last experiment. 41. Carbonate of lime is soluble in carbonic acid, but not soluble in water. 42. Lime water possesses alkaline properties, for when poured into blue vegetable infusions, they turn green, TO CHEMWTRY. 141 43. Lime water, mixed with mild alkali in solution, disengages the carbonic acid, and precipitates the lime in a white powdery form, and the alkali is left pure. 44. The specific gravity of lime is 2.3. 45. It requires an intense degree of heat for its fu- sion, and has not been volatilized. Its taste is caustic, astringent and alkaline. 4'J. Slacked lime is called hydrate of lime, in conse quence of its combination with water. Its solubility is not increased by heat. 47. Slacked lime is a compound of 3.56 parts lime,and 1.125 water. 48. Lime combines with phosphorus, and forms a compound of a dark brown colour, called phosphuret of lime; which, when thrown into water, disengages phos- phuretted hydrogen gas in small bubbles, that explode U> succession, at the surface of the water. Exp. Provide a glass tube sealed at one end, into the sealed end put a small bit of phosphorus; the middle part must be filled with pieces of lime, about the size of peas. After heating the latter with a lamp, apply anoth- er lamp to the end containing the phosphorus, and cause the vapour to pass through the lime, the combination will be completed, 49. Sulphur combines with lime, by fusing the con- stituents together in a covered crucible. It is called sul- phuret of lime. 50. It possesses the following properties. It is of a reddish colour, and very acrid. It deliquesces on expo- sure to the air, apd becomes of a greenish yellow hue.— When it is put into water, hydroguretted sulphuret of lime is immediately formed. It acts corrosively on ani- mal bod.es, and is a powerful reagent in precipitating metals from their solutions. 142 INTRODUCTION 51. Lime combines with chlorine and forms a sub- stance called chloride of lime or calcium. When lime is heated in contact with chlorine, oxygen is expelled,. and chlorine is absorbed. 52. It is a semi-transparent crystalline substance, fu- sible at a strong red heat; a non-conductor of electricity ; has very little taste ; rapidly absorbs water from the at-. mosphere, and is very soluble in waten 53. Lime has a metallic base, called calcium; it is of a bright silvery appearance, and combines with oxygen- only in one proportion, which is lime. It burns when gently heated, producing dry lime. 54. The most important applications of lime are in agriculture and building. 55. Quicklime is found to be injurious to plants, but in its combination with carbonic acid, it is an important ingredient. 56. Lime acts as a cement in two ways ; in its combi- nation with water, and in that of carbonic acid. 57. When quicklime is rapidly made into a paste with water, it soon loses its softness; the water and the lime form together a solid coherent mass, which consists of 1 part of water to 3 parts of lime. When hydrate of lime, whilst it is consolidating, is mixed with red oxide of iron, alumina, or silica, the mixture becomes harder and more coherent, than when lime alone is used. Illustration. This is owing to a certain degree of chemical attraction between hydrate of lime and these bodies, and they render it less liable to decompose by, the carbonic acid in the air, and less soluble in water. 58. The basis of all cements that are used for works which are to be covered with water, must be formed, from lime. TO CHEMISTRY. .]4J 59. Puzzolano is composed principally of silica, alu- mina and oxide of iron ; and it is used, mixed with iron, to form cements intended to be employed under water. 60. Tarras, is basaltes decomposed, two parts of slack- ed lime, and one of tarras, form the cement used in con- structing the great dykes in Holland. PRACTICAL QUESTIONS. To what is the term earth applied ? What are the names and number of the earths ? What are the earths considered to be ? How are they divided by some chemists ? What do these classes include ? What are the earths found in plants ? Which are the most common in vegetables ? What part of the ashes of plants do they form ? From what does the power of producing intense heat in turf and peat, arise ? Of what is turf or peat composed ? What use are earths in combustion ? What was Count Rumford's recommendation ? Of what are precious stones composed ? In what state are the earths found in precious stones ? How do you account for this ? How must you proceed in examining the earths ? What is barytes ? What are its properties ? How is its affinity for sulphuric acid ? What experiment can you adduce to prove this ? Illustrate the principle. How do you shew its alkaline properties on vegeta bles? Will barytes combine with sulphur ? What are the properties of sulphuret of barytes ? 144 INTRODUCTION What are the constituents of hydrosulphuret of barytes? What are the properties of the crystals of the hydro- sulphuret ? What is the hydroguretted sulphuret ? How may phosphuret of barytes be formed ? What are its properties ? What are the characteristics of barium ? In how many proportions does it combine with oxy- gen ? What property do the salts of barytes possess ? What is strontian ? What are the characteristics of strontian ? How does it differ from barytes ? What is the basis of strontian, and its properties ? What effect has strontian on inflammable substances ? How would you illustrate this by experiment ? Is strontian caustic ? What is lime ? What does it possess, when deprived of carbonic acid ? How much does carbonate of lime lose by calcination ? How can you preserve pure lime ? What is the effect, when small quantities of water are added to quicklime ? Illustrate this. How much water does lime require for its solution ? How will you prove that water attracts carbonic acid from the atmosphere ? In what is carbonate of lime soluble ? How do you prove that lime water possesses alkaline properties ? What effect has mild alkali on water ? What is the specific gravity of lime ? Can lime be fused and volatilized ? What is slacked lime called ? TO CHEMISTRY. I45 Of what is it compounded ? What is the combination of lime with phosphorus ? How would you prepare phosphuret of lime ? How is sulphur combined with lime ? What properties does it possess ? What is chloride of lime ? What are its properties ? What is the base of lime ? What are the most important applications of lime ? What effect has it on vegetation ? How does lime act as a cement ? What is the effect of quicklime, when rapidly made into a paste with water ? Is there any way to render mortar harder and more coherent, than when lime alone is used ? To what is this owing ? Of what must be the basis of all cements that are cov- e red" with water ? What is Puzzolana 1 What is Tarras •? CHAP. XV. Of Magnesia—Alumina— Yttria—Glucina—Zirconia— Silica, and Thorina. 1. Magnesia is never found pure in nature, but is usually procured from the sulphate of magnesia, Epsom salt, which exists in sea water, and in mineral springs. Exp. Dissolve the sulphate of magnesia in water, and add to it half as much in weight of pure potash; a 13 146 INTRODUCTION decomposition takes place, the sulphuric acid of the sul- phate unites with the potash in consequence of superior affinity, and the magnesia is precipitated. Wash the precipitate several times with pure water, and the mag- nesia in a state of an hydro-carbonate will be obtained. To procure it pure, calcine it in a crucible, until it will no longer effervesce with distilled vinegar. 2. Magnesia, when pure, is destitute of smell, and has a slight alkaline taste. It ^inverts vegetable blues to green, gives out heat like lime, on the affusion of water. It is very sparingly soluble in water, requiring for its so- lution 2000 times its weight. It forms with acids ex- tremely soluble salts. 3. The specific gravity of magnesia is 2.3. 4. It is infusible, except by the oxyhydrogen blow pipe. It has scarcely any taste or smell. 5. When precipitated from the sulphate, it is combin- ed with water, constituting an hydrate, which separates by a red heat. 6. This hydrate contains about one fourth its weight of water. 7. When magnesia is exposed to the air, it very slow- ly attracts carbonic acid. 8. Magnesia combines with sulphur, forming a sul- phuret. 9. The magnesia of commerce is often found mixed with carbonate of lime ; if this be the case, sulphuric acid will detect the fraud ; it dissolves the magnesia. while the lime falls to the bottom. Exp. Take a small quantity of magnesia, and add a little sulphuric acid, diluted with five or six times its weight of water ; if the solution be transparent, it is pure, but if there be a sediment, it may be considered as mixed with lime. TO CHEMISTRY. 147 10. The base of magnesia is called magnesium, and may be obtained by passing potassium in vapour through it, heated to whiteness in a tube of platinum, out of con- tact of the air, and then introducing a small quantity ©f mercury, and heating it gently in the tube ; an amalgam is obtained, which must be distilled, excluded from the atmosphere, a dark grey metallic film will be obtained, which is infusible at the point at which plate glass soft- ens, and which in the process of the distillation with the mercury, renders the glass black at its point of contact with it 11. The film as above obtained, burns with a red light when strongly heated, and becomes converted into a white powder, which is magnesia. 12. When exposed to the air, magnesium absorbs oxy- gen, and is converted into magnesia. 13. According to late experiments, magnesia consists of 60 parts magnesium, and 40 oxygen. 14. Magnesia is found to exist in talc, asbestos, amian- thus slate, and in a certain limestone, which*contains il in very great quantities. 15. Its principal use is in medicine, chiefly to com- bine with, and neutralize the acids found in the stomach. OF ALUMINA. 16. Alumina derives its name from the compound salt called alum, or more properly sulphate of alumina, of which it forms the base. The purest native alumina is found in the sapphire and ruby. Exp. Dissolve alum, sulphate of alumina, in 20 times its weight of water, and add to it a little of the carbonate of soda, to throw down any iron that there may chance to be combined with it; then pour the supernatant liquid, a little at a time, into the water of ammonia, taking care 148 INTRODUCTION not to,add so much as to saturate the ammonia ; the am- monia will unite with the sulphuric acid of the alum, and the earthy basis of the latter is separated in a white spongy precipitate. This must be thrown on a filter, washed with pure water, and then dried. 17. Alumina thus obtained, possesses the following properties. It is white, soft to the touch, adheres to the tongue, forms a smooth paste without grittiness in the mouth, insipid, inodorous, produces no change in vegeta- ble colours, insoluble in water, but mixes with it readily in every proportion, and retains a small quantity with considerable force. It is infusible in the strongest heat of a furnace, becoming merely more compact and hard. It is fusible in small quantities by the oxyhydrogen blow pipe. 18. In the state of powder, its specific gravity is 2.000. 19. From analogy, we are led to conclude, .that the base of alumina is a metal possessing similar properties as other earthy bases ; but this subject has not been ful- ly investigated. 20. Alumina is a constituent of every soil, and almost every rock. It is the basis of pottery, bricks and cruci- bles. 21. In the state of clay, it forms large strata of the earth, gives consistency to the soil of valleys, and of all low and damp spots, such as swamps and marshes. 22. The solid compact soils, such as are fit for corn, owe their compactness in a great measure to alumina. This earth is therefore used to improve sandy or chalky soils, which do not contain a sufficient quantity of water for the purpose of vegetation. 23. Combined with silex and water, which harden it, alumina forms, bricks and porcelain; the silex renders it TO CHEMISTRY. 149 capable of a degree of vitrification, and makes it per- fectly fit for its various purposes. 24. Bricks consist of baked clay, silex, or common sand, and an oxide of iron to which they owe their red colour. 25. The common earthen ware is made of clay and sand. 26. For porcelain, the purest kind of sand is used, with the best kind of clay; it owes its semi-transparency to a kind of vitrification of the sand. 27. Earthen ware and porcelain are covered with a glazing, to render them more beautiful, and to prevent their being corroded by a variety of substances. 28. The glazing for porcelain consists of enamel, a . fine white opake glass, formed of metallic oxides, sand, salt, and such other materials as are susceptible of vitri- fication.' 29. The glazing of common earthen ware is made principally of the oxide of lead, or sometimes merely of common salt, as for stone ware; this, at a certain tem- perature, will run into an opake glass. 30. The colours used for painting porcelain are all metallic oxides, capable of enduring a great degree of heat without injury; by undergoing different degrees of oxidation, the colours are strengthened and developed. Illustration. The oxide of gold is employed for pur- ple, red is given by the oxide of iron, yellow by the ox- ide of silver, green by copper, and blue by cobalt. 31. Alumina has a strong affinity for vegetable col- ouring matter, and is used as a mordant by the dyer and calico printer. 32. Alumina is found combined in different propor- tions, in various gems and other minerals. Many of the - 13* 150 1 INTRODUCTION precious stones are almost wholly formed of alumina, coloured with some metallic oxide. Observation. Such as ruby, oriental, sapphire, ama- thysts, &c. 33. Fuller's earth is a compound of alumina and silex. It is of great importance in scouring cloth, and in taking out spots of grease from the floor and other substances, from the affinity which alumina manifests for greasy Substances. 34. On the principle, that the bulk of alumina dimin- ishes in proportion to the heat to which it is exposed, is founded the pyrometer of Mr. Wedgwood, for measuring high degrees of temperature. 35. The salts of alumina possess the following charac- ters. 1. Most of them are very soluble in water, and their solutions have a rough sweetish taste. 2. Ammonia precipitates their earthy base, even though they have been previously acidulated with mu- riatic acid. 3. At a strong heat, they give out a portion of their acid. 4. Phosphate of ammonia gives a white precipitate. 5. Hydriodate of potash produces a flocculent precipi- tate of a white colour, passing into a permanent yellow. 6. These salts are not affected by oxalate of ammonia, tartaric acid, ferroprussiate of potash, or tincture of galls; by the first two tests they are distinguished from yttria, and by the last two from that earth and glucina. 7. If bisulphate of potash be added to a solution of an aluminous salt, moderately concentrated, octahedral crys- tals of alum will form. TO CHEMISTRY. 151 OF YTTRIA, OR ITTRIA. 36. Yttria is an earth, discovered in 1794, in a stone from Ytterby in Sweden, by professor Gadolin. 37. It is perfectly white, when not contaminated with oxide of manganese, from which it is not easily freed.— Its specific gravity is 4.842. It has neither taste nor smell. It is infusible by itself, but when mixed with borax, melts into a transparent glass. It is insoluble in water and caustic fixed alkalis, but is soluble in carbo- nate of ammonia. It is soluble in most of the acids. 38. Yttria is considered as having a metallic base similar in its properties to the bases of the other earths, and is called Yttrium. OF GLUCINA. 39. Glucina is nn earth obtained from the beryl or emerald, a transparent stone of a green colour, found crystallized in the mountains of Siberia. It was discov- ered by Vauquelin. 40. Glucina derives its name from the Greek word signifying sweet, because it imparts a saccharine taste to all the acids with which it unites, and forms salts. 41. It is a white soft powder, light, insipid and ad- hering to the tongue. It does not change vegetable blues. It does not harden by heat, and is infusible. It is insoluble in water, but forms with it a slight ductile paste. It is dissolved by potash, soda and carbonate of ammonia, but not by pure ammonia. It unites with sul- phuretted hydrogen. Its salts have a saccharine taste, with somewhat of astringency. 42. Glucina is considered as a compound of oxygen and a certain metallic base called Glucinum. i'.yZ INTROH.CI10N OF ZIRCONIA. 43. Zirconia is a substance found in the zircon or jargon, and the hyacinth. 44. It pos-osscs neitheu taste nor smell. It is infusi- ble before the blow pipe, but when subjected to a very high temperature in a charcoal crucible, it undergoes a sort of imperfect fusion, acquires a greyish colour, and a porcelaneous appearance. It is insoluble in water, or in the alkaline solutions. Its specific gravity is 4.3. 45. Zirconia has a considerable affinity to water, and when precipitated from its acid solutions, it is called an hydrate, which has the appearance of rosin or glue. 46. The hydrate contains more than 20 per cent of water, which may be expelled by heat 47. Zirconia is considered as a compound of a metal and oxygen. Potassium when brought into contact with zirconia, ignited to whiteness, is, for the most part, con- verted into potasli; and dark particles, which, when ex- amined by a magnifying glass, appear metallic in some parts, of a chocolate brown in others, are found diffused through the potash and the decompounded earth. OF SILICA. 48. Silex or silica abounds in almost all fossils and precious stones, particularly those which strike fire with steel. It exists nearly pure in transparent quartz or rock crystal. Exp. To obtain silica, ignite powdered quartz with three parts of pure potash in a silver crucible, dissolve the fused compound in water, add to the solution a quan- tity of acid, sufficient to saturate the alkali, then evapo- rate to dryness, a fine gritty powder will be obtained, TO CHEMISTRY. 153 which being well washed with distilled water, and ignit- ed, will leave pure silica. 49. It is a white powder, of a harsh and gritty feel. Specific gravity 2.66. It is fusible only by the oxyhy- drogen blow pipe. It is acted upon by no acid, but the fluoric, and appears to be insoluble in water, although nature by some process dissolves it, and crystallizes it in the form of rock crystal. 50. The value of siliceous earth in many arts is very extensive. It is used in the manufacture of glass, potte- ry, bricks, porcelain, &c. It likewise forms one of the ingredients of the most durable mortars and cements. 51. Silica and potash, or soda fused together, form glass. It is of different qualities, according to the ingre- dients used. Illustration. Flint glass is formed of soda or potash, flints, and an oxide of lead. Window glass is composed of an alkali and fine sand. Bottle glass of kelp and com- mon sand ; its green colour is owing to the presence of iron. Exp. Take one part of pure white sand, and three parts of potash, mix them into a paste, and fuse them in a crucible, the result is glass. 52. Silica is considered as a compound of a peculiar combustible principle with oxygen. By passing the va- pour of potassium over silica in an ignited tube, Sir H. Davy obtained a dark coloured powder, which contained silicon, or the basis of silica. 53. It is capable of sustaining an high temperature, without any change ; water of potash seems to form with it an olive coloured solution. But as this basis is decomposed by water, it is not possible to wash away the potash by this liquid. Berzelius and Stromeyer tri- ed to form a compound of silicon with iron, by exposing 154 INTRODUCTION to the strongest heat of a blast furnace, a mixture of 3" parts of iron, 1.5 silica, and 0.66 charcoal. It was in the state of fused globules. These freed from the charcoal, were white and ductile, and their solution in muriatic acid evolved more hydrogen, than an equal weight of iron. The specific gravity of the alloy was from 6.7 to 7.3, while that of the iron used was 7.8285. Nothing definite, however, can be inferred from these experi- ments. 54. Sir H. Davy found that more than three parts of potassium were necessary to decompose one of silica.— Hence it maybe inferred, that 100 parts of silica contain about 60 of oxygen. 55. Silicon is insoluble in alcohol, ether, or the oils, at any temperature, and is a non-conductor of electricity. 56. Silica forms with fluorine, a substance which though not sour, seems to partake of the properties of an acid, and called Jluo-silicic acid, or silicated fluoric acid. OF THORINA. 57. Thorina is a new earth, discovered in 1816, by Berzelius. He found it in small quantities in the gadoli- nite, and two new minerals, which he named the deuto- fluate of cerium, and the double fluate of cerium and yttria. 58. It has the appearance of a gelatinous semi-trans- parent mass. When washed and dried it becomes white, absorbs carbonic acid, and dissolves with effervescence in acids. When dissolved in muriatic acid, the solution has a yellowish colour, but it becomes colourless when mixed with water. 59. It differs from all other species of earths, except zirconia ; in this, that the neutral solutions have a pure- TO CHEMISTRY. 155 "ly astringent taste, which is neither sweet, saline, bitter, nor metallic. 60. When dissolved in sulphuric acid, with a slight excess of acid, and subjected to evaporation, it yields transparent crystals, which are not altered by exposure to the air, and which have a strong styptic taste. 61. It is soluble in nitric and muriatic acids, and com- bines with avidity with carbonic acid. 62. Thorina differs from zirconia by the following properties. 1. After being heated to redness, it is still capable of being dissolved in acids. 2. Sulphate of pot- ash does not precipitate it from its solution, while it pre- cipitates zirconia containing even a considerable excess of acid. 3. It is precipitated with oxalate of ammonia, which is not the case with zirconia. 4. Sulphate of thorina crystallizes readily, while sulphate of zirconia, when free from alkali, forms, when dried, a gelatinous transparent mass, without any trace of crystallization. 63. The supposed metallic base of thorina, is called Thorinum. It has not yet been extracted. PRACTICAL QUESTIONS. How is magnesia procured ? Illustrate it by experiment What are the properties of magnesia ? What is its specific gravity ? Is it fusible ? What is the hydrate of magnesia ? How much water does it contain ? What is the effect on magnesia when exposed to the air? With what is the magnesia of commerce mixed, and how is the fraud detected ? How is the base of magnesia obtained ? 156 INTRODUCTION How do you prove that this film is magnesia ? Of what does magnesia consist ? Where is magnesia found to exist ? What is the use of magnesia ? What is alumina ? How do you procure pure alumina 1 What are the properties of alumina thus obtained ? What is its specific gravity 1 How do you conclude that the base of alumina is « metal ? Of what is alumina the constituent ? What does it form in the state of clay ? What use is this earth in agriculture ? Of what use is silex in forming bricks and mortar ? Of what do bricks consist ? Of what is common earthen ware made ? What is used for porcelain ? What is the use of glazing earthen ware and porce- lain ? Of what does the glazing for porcelain consist ? Of what is the glazing of common earthen ware and stone ware made ? What are the colours used fbr painting porcelain ? Why is alumina used as a mordant ? Where is alumina found ? What is fuller's earth, and why does it remove grease spots ? On what principle is Wedgwood's pyrometer formed ? What are the characteristics of the salts of alumina ? What is yttria ? What are its characteristics ? Has it a metallic base ? What is glucina ? From what does it derive its name 7 TO CHEMISTRY. 157 What are its characteristics ? What is glucina considered to be ? What is zirconia ? What are its properties ? Has it any affinity for water ? How much water does the hydrate contain ? How is it proved that zirconia has a metallic base Where is silex or silica found ? How do you obtain it pure ? What are its properties ? Is silica of any value ? Of what is glass composed ? What is silica considered to be ? What are the properties of its base ? How much potassium is requisite to decompose it t Is silica soluble in alcohol, ether and oils ? What does silica form with fluorine ? What is thorina, and where found ? What are its characteristics ? How does it difler from other species of earths ? What is the sulphate of thorina ? Is it soluble in other acids ? How does thorina differ from zirconia ? What is the base of thorina ? CHAP. XVI. Of Acids. 1. Acids are the most important class of all chemical compounds ; they consist of a certain base, called a radi- cal, and an acidifier. 14 158 INTRODUCTION 2. The general properties of the acids are, 1. Their taste iK, for the most part, sour, as their name denotes ; and in the strongest, it is acrid and corrosive. 2. They generally combine with water in every proportion, with a condensation of volume and evolution of heat. 3. With a few exceptions, they are volatilized and decomposed by heat. 4. They usually change the purple colours of vegetables to a bright red ; and 5. They appear to unite in definite proportions, with earths, alkalies, and metallic oxides, forming salts. 3. Until within a few years, oxygen was considered to be the only acidifier, whence its name; but late ex- periments have led some to doubt the correctness of the hypothesis, and to consider other substances as acidifi- ers. 4. By the new nomenclature, acids are distinguished by the name of the base, and its degree of oxidation, or the quantity of oxygen it contains, by the termination of that name, in ous or ic. Illustration. Sulphurous acid is that formed by a pro- portion of oxygen combined with sulphur : sulphuric, that which results from the combination of sulphur with another quantity of oxygen. 5. Several of the radicals are capable of combining with a quantity of oxygen so small as not to impart tp them the properties of acids ; in these cases they are converted into oxides. Exp. Expose sulphur to the atmosphere with a de- gree of heat that will not produce inflammation, it will absorb a quantity of oxygen, and will assume a red or brown colour. This is the first degree of oxygenation; the second is the sulphurous acid ; the third hypo sul- phurous : the fourth the sulphuric; and if there be TO CHEMISTRY. 153 another, it will be the super oxygenated sulphuric acid, or the hypo sulphuric. 6. Some of the acids are susceptible of only one de- gree of oxygenation, others of two or three , there are very few that will admit of more. 7. The class of acids has been distributed into three orders, by many chemists, viz. the mineral, vegetable and animal acids. But a more specific difference is now necessary. They have also been arranged into those which have a single, and those of a compound basis, or radical, This arrangement, however, is not only vague, but liable in many other respects to considerable objec- tions. 8. The chief object of classification is to give gener- al views to beginners in the study, by arranging together such substances as have analogous properties, or compo- sition. 9. The number of acid substances hitherto discover- ed are seventy-five, and may be arranged in the follow- ing divisions and subdivisions. 1. Acids from inorganic nature, or which are procurable without having recourse to animal or vegetable products. 2. Acids obtained by means of organization. The first division is subdivided into three families ; 1st. Oxygen acids. 2d. Hydrogen acids. 3d. Acids des- titute of both these supposed acidifiers. Division 1st.—Acids from inorganic nature. First family—Oxygen acids. Section 1st, Non-metallic. 1. Boracie. 5. Chloro-carbonous. 2. Caibonic. 6. Nitrous. 3. Chloric. 7. Nitric. 4. Perchloric 8. Iodic; It>v, INTRODUCTION 9. Hypophosphorous. 10. Phosphorous. 11. Phosphoric. 12. Hyposulphurous. 13. Sulphurous. 14. Sulphuric. 15. Hyposulphuric 16. Cyanic ? Section 2d, Oxygen acids.—Metallic. 1. Arsenic. 6. Columbic. 2. Arsenious. 7. Molybdic. 3. Antimonious. 8. Molybdous. 4. Antimonic. 9. Tungstic. 5. Chromic. Second family—Hydrogen acids. 1. Fluoric. 5. Hydroprussic. 2. Hydriodic. 6. Hydrosulphurous. 3. Hydrochloric. 7. Hydrotellurous. 4. Ferroprussic. 8. Sulphuroprussic. Third family—Acids without oxygen or hydrogen. 1. Chloriodic. 3. Fluoboric. 2. Chloroprussic. 4. Fluosilicic. Division 2d 1. Aceric. 2. Acetic. 3. Amniotic. 4. Benzoic. 5. Boletic. 6. Camphoric. 7. Caseic. 8. Citric. 9. Formic. 10. Fungic. 11. Gallic. 12. Kinic. 13. Laccic; —Acids of organic origin. 14. Lactic. 15. Lampic. 16. Lithic. 17. Malic, 18. Meconic. 19. Menispermic. 20. Margaric. 21. Melassic. 22. Mellitic. 23. Moroxylic 24. Mucic. 25. Oleic. 26. Oxalic. TO CHEMISTRY. 161 27. Purpuric. 33. Sebacic. 28 Pyrolithic. 31. Suberic. 29. Pyromalic. 35. Succinic. 30. Pyrotartaric. 36. Sulphovinic ? 31. Rosacic. 37. Tartaric. 32. Saclactic. 33. Zumic. 10. The acids of organic origin are all decomposable at a red heat, and afford generally carbon, hydrogen, oxygen, and in some few cases, nitrogen. 11. The acids of simple and known radicals are capa- ble of being decomposed by combustible bodies, to which they yield their oxygen. Exp. Drop a little sulphuric acid on a piece of bright iron, a black spot will be produced, which is an oxide formed by the oxygen of the acid, combining with the iron. 12. Acid added to a compound combustible substance, will combine with one or mere of the constituents oi" that substance, and occasion a decomposition. Exp. Take a dry piece of pine wood and pour upon it some sulphuric acid, in a short time the wood becomes. black. Illustration. Wood is composed of hydrogen and car- bon, the oxygen of the acid combines with the hydrogen of the wood, to form water, and the carbon remaining, appears of its usual black colour. 13. When vegetable acids are poured on wood, they do not produce the same effect as mineral acids, because their bases are composed of hydrogen and carbon ; the oxygen, therefore, will not easily quit the radical where it is already united with hydrogen. The strongest veg- etable acids may, perhaps, yield a little of their oxygen to the wood, and produce a stain, but the carbon will not be sufficiently exposed to assume its black colour. 14* 162 INTRODUCTION 14. Mineral acids possess the power of charring wood in different degrees. 15. Boracic acid is obtained from borax, a substance brought from the East Indies and South America ; it is crystallizable in the form of thin irregular hexagonal scales, of a silvery whiteness, having some resemblance to spermaceti. It has a sourish taste at first, and then a bitterish cooling one, and at last an agreeable sweetness. It has no smell, but when sulphuric acid is poured upon it, its odour resembles that of musk. Its specific gravity in the form of scales is 1.479 ; after it has been fused, 1.803. It is not altered by light. In its crystallized state, it is composed of 57 parts of acid, and 43 of water. 16. The radical of the boracic acid is boron. It is solid, tasteless, inodorous, and of a greenish brown col- our. Its specific gravity is somewhat greater than wa- ter. 17. Carbonic acid is formed by the combustion of carbon, whether in the form of charcoal, or in its purest form of diamond. Exp. Light a piece of charcoal and suspend it under a receiver in a water bath; after the charcoal is extin- guished, examine the air and it will be found to be car- bonic acid. 18. Carbonic acid may be separated from the air with which it is mixed, by introducing into a receiver, containing carbonic acid, a little caustic lime or caustic potash, which soon attracts the whole of the carbonic acid to form a carbonate, the alkali is found increased in weight, and the volume of the air is diminished by a quantity equal to that of the carbonic acid which was mixed with it. 19. Carbonic acid abounds in great quantities in na- ture, an 1 appears to be produced in a variety of circum- TO CHEMISTRY. 163 stances. It composes T4^ of the weight of limestone, marble, calcareous spar, and other calcareous substan- ces. 20. Water at low temperature and at common pres- sure, absorbs somewhat more than its bulk of fixed air, and then constitutes' a weak acid. Heated water absorbs less ; if water impregnated with this acid he exposed on a brisk fire, the rapid escape of the gas in bubbles affords an appearance as if the water were at the point of boil- ing, when the beat is not equal to 100°. 21. No degree of cold has exhibited this acid in a condensed state of fluidity. 22. Carbonic acid gas is emitted in large quantities from bodies in the state of the vinous fermentation. On account of its great weight, it occupies the upper part of the vessels in which the fermenting process is going on. Exp. 1. Dip a lighted taper or candle into the empty space of a vessel, containing a liquor undergoing the vi- nous fermentation, it will be immediately extinguished, and the smoke remaining in the carbonic acid gas ren- ders its surface visible, which may be thrown into waves, by agitation, like water. Exp. 2. If a dish of water be immersed in this gas and quickly agitated, it soon becomes impregnated, and acquires a pungent taste. Exp. 3. If a candle or small animal be placed in a deep vessel, the former becomes extinct, and the latter expires in a few seconds, after the carbonic acid gas is poured from another vessel upon them, though the eye is incapable of distinguishing any thing that is poured. 23. Carbonic acid reddens infusion of litmus ; but the redness vanishes on exposure to the air, as the acid flies off. 164 INTRODUCTION 24. Light, passing through carbonic acid, is refract- ed, but it does not effect any sensible alteration in it, though it appears from experiment, that it favours the separation of its principles by other substances. 25. The specific gravity of carbonic acid compared with that of atmospheric air, is as 1.5236 to 1.0000. 26. Water by absorbing its volume of this gas, ac- quires a specific gravity of 1.0015. By pressure and by means of forcing pumps, water may be made to absorb two or three times its volume of this gas. When there is a little soda added, it becomes the aerated, or soda water of the shops. 100 cubic inches of oxygen weighs 33.8 grs. and 100 cubic inches of carbonic acid, 46.5 grs. ; hence the weight of combined charcoal in 100 cubic inches of carbonic acid is 12.7 grs. 27. Carbonic acid unites with the alkalies, earths, and some of the metallic oxides,forming salts called carbonates,. which poseess peculiar properties. 28. Carbonates are composed either of one prime of the acid, and one of the base, or of two of the acid and one of the base ; the former are called carbonates, the latter bi-carbonates. 29. Carbonic acid gas is not respirable, yet it is formed in the lungs,; so that the air which we expire, al- ways contains a certain proportion of carbonic acid, which is much greater than that which is found com- monly in the atmosphere. Exp. Prepare some lime water, and breath into it through a tube or pipe, the water immediately becomes turbid in consequence of the union of the lime with thai carbonic acid of the lungs. TO CHEMISTRY. 166 PRACTICAL QUESTIONS. Of what do acids consist ? What are the general properties of the acids ? Is oxygen the only acidifier ? How are acids distinguished by the new nomencla- ture ? Illustrate it. Suppose the oxygen should not produce an acid, what would you call it ? Of how many degrees of oxygenation are the acids capable ? How are the class of acids distributed 1 What is the object of classification ? What are the number of acids ? Name the acids. How are the acids of organic origin decomposable 1 How are acids of simple and known radicals decom- posable ? Illustrate by experiment. Why does sulphuric acid turn wood black ? Why do not vegetable acids produce the same effect ? Do mineral acids possess the power of charring wood equally ? What is boracic acid, its specific gravity and proper- ties ? What is its base ? How is carbonic acid formed ? How do you form it in experiment ? How can you separate carbonic acid from the air with which it is mixed ? Where is carbonic acid found ? What effect has water upon it ? Can it be condensed into fluidity ? Is it emitted from vinous fermentation ? 106 INTRODUCTION Prove it by experiment. Has it any effect on vegetable colours ? What effect has it on light ? What is its specific gravity ? What specific gravity does water acquire by absorbing this gas ? With what does carbonic acid unite ? What are carbonates and bi-carbonates ? is this gas respirable ? CHAP. XVII. Continuation of Acids, 1. Muriatic acid is that obtained from sea salt, Muri- ate of soda, by distillation with sulphuric acid. It is pro- cured in the form of gas and absorbed in water. 2. When this gas is received in glass jars over mer- cury, it is invisible and possesses all the mechanical prop- erties of air. Its odour is pungent and peculiar. Its taste acrid and corrosive. It will not support respira- tion or combustion, is changed in bulk by alteration of temperature. Exp. Fill a jar with the gas and immerse in it a lighted taper, it is immediately extinguished. 3. Muriatic gas consists of chlorine and hydrogen united in equal volumes, and by the new nomenclature, called hydro chloric acid. Exp. When potassium, tin or zinc, is heated in con- tact with this gas over mercury, one half of the volume disappears, the remainder is found to be pure hydrogen, and the solid residue is found to be a metallic chloride. TO CHEMlSiRY. 167 4. Muriatic acid gas has a very strong affinity for wa- ter, as is evident, from its forming a white cloud in con- tact with the atmosphere, which proceeds from its com- bination with aqueous vapour. 5. The solution of this gas is commonly of a pale yellow colour ; it may be rendered colourless by repeat- ed distillations. 6. The cause of the colour is not known. 7. Its specific gravity as commonly obtained, is about 1.170, in which state it contains about 2b per cent of dry acid. 8. No liquid acid appears capable of existing when the proportion of gas is much more than four or five hundred times the volume of water employed in its preparation. At this strength, it appears to contain about 48 per cent of the acid gas. Its specific gravity is 1.5, and its boiling point 60°. 9. Its boiling point gradually lessens with a less pro- portion of gas, till it arrives at 12 per cent of gas, when it boils at 232°. 10. When the acid gas is in greater proportion than 12 per cent, the gas escapes until it arrives at that stand- ard ; and when in a less proportion, the water escapes, to reduce it to the same standard. 11. Muriatic acid combines with earths, alkalies, and metallic oxides, forming substances called muriates. 12. Muriates, when in a state of dryness, are chlo- rides, being a combination of the base with the chlorine of the acid, but the least moisture causes them to pass to the state of muriates or hydrochlorides. Chlorides, prop- erly speaking, contain neither an acid nor an alkali. 13. Chloric acid has the same base as muriatic, name- ly, chlorine. 168 INTRODUCTION Exp. When a current of chlorine is passed for some time through a solution of barytic earth in warm water, a substance called hyperoxymuriate of barytes is formed as well as some common muriate. The latter is sepa- rated by boilh'g some phosphate of silver in the com- pound solution. The former may then be obtained by evaporation in fine rhomboidal prisms. When a few drops of sulphuric acid diluted is added, the liquid be- comes sensibly acid. By continuing to add sulphuric acid with caution, an acid liquid entirely free from sul- phuric acid which has united with the barytes, will be obtained, which is chloric acid dissolved in water. 14. Its properties are ; it has no sensible smell. Its solution in water is perfectly colourless. Its taste is very acid, and it reddens litmus without destroying the colour. It produces no alteration on solution of indigo in sulphu- ric acid. Light does not decompose it. It may be kept a long time exposed to the air, without sensible diminu- tion. When concentrated, it has something of an oily consistence. When exposed to heat, it is partly decom- posed into oxygen and chlorine, and partly volatilized without alteration. 15. Chloric acid is decomposed by muriatic, sulphu- rous acid, and sulphuretted hydrogen. Combined with ammonia, it forms a fulminating salt. It does not pre- cipitate any metallic solution. It readily dissolves zinc, disengaging hydrogen ; but it acts slowly on mercury. 16. Chloric ac id forms salts with the alkalies and earths, Called chlorates, or hyperoxymuriates. 17. Perchloric acid is procured by pouring three parts of sulphuric acid on one of chlorate of potash in a retort, perchlorate of potash will be obtained, and by adding sulphuric acid, at 280° perchloric acid is produced, TO CHEMISTRY. 169 It seems to consist of 7 parts of oxygen, combined with 1 of chlorine, or 7.0 -f- 4.15. 18. Chloro carbonous acid is composed of chlorine and protoxide of carbon. Observation. Experiments made by Dr. John Davy, go to prove that chlorine and carbonic oxide unite rap- idly, when exposed to the direct solar beams, and one volume of each is condensed into one volume of the com- pound. The resulting gas possesses very peculiar prop- erties, approaching to those of an acid. From the pe- culiar influence of the sun beams in effecting this combi- nation, Dr. Davy called it phosgene gas. 19. Its properties are; it does not fume in the at- mosphere. Its odour is different from that of chlorine. It affects the eyes in a peculiar manner, producing a rapid flow of tears, and occasioning painful sensations.— It reddens dry litmus paper; and condenses four volumes of ammonia into a white salt, while heat is evolved.— Neither sulphur, phosphorus, oxygen, nor hydrogen, though aided by heat, produce any change on the acid gas ; but oxygen and hydrogen together, in due propor- tion, explode in it. On exposure to water, it is convert- ed into muriatic and carbonic acid gases. 20. According to Thenard, chloro carbonous acid is a compound of muriatic and carbonic acids, resulting from the mutual actions of the oxymuriatic acid and car- bonic oxide. 21. Nitrous acid was formerly called fuming nitrous acid. It is in the form of an orange coloured liquid. It is so volatile as to boil at the heat of 82°. 22. Its specific gravity is 1.450. 23. When mixed with water it is decomposed, and nitrous gas is disengaged, with effervescence. 15 170 1N1R0UVCT1ON 2t. It is composed of one volume of oxygen, united with two of nitrous gas. It appears to form a distinct genus of salts, called nitrites. 25. Nitric acid is composed of oxygen and nitrogen, which are the constituents of the atmosphere, and differs in nothing from the air we breathe, except in the pro- portion of the ingredients, and in their complete chemi- cal union. Exp. 1. Mix the two gases in a glass tube, and pass through them a number of electric explosions, the gases will combine, and nitric acid will be formed about the inside of the tube. This method of proving the compo- sition, is called the synthetic. Exp. 2. Place a porcelain tube across a furnace, and adjust the apparatus as in the decomposition of water, when the tube becomes red hot, pass the acid through it, it will be found to consist of nitrogen and oxygen gases. This method is called the analytical method of proving it 26. This acid contains a large proportion of oxygen, but retains it with very little force. It is therefore very corrosive, and destroys, or burns, all kinds of organized matter. E\p. Take strong nitric acid and pour a few drops into a glass, containing oil of turpentine, a violent in- flammation immediately ensues. This experiment suc- ceeds best when a little sulphuric acid is added with the nitric. 27. The properties of nitric acid are ; it is clear and colourless, like water. Its smell pungent. Its taste ex- ceedingly acid, and it imparts a yellow stain to the skin. 28. Nitric acid dissolves or oxidates almost all met- als in consequence of the facility with which it parts with its oxygen. TO CHEMISTRY. ni .29. Nitric acid is generally obtained from nitre, or salt petre, by distillation with sulphuric acid. When di- luted, it is called aquafortis. Nitric acid combines with alkalies, earths and metallic oxides, forming a genus of salts called nitrates. 30. Iodic acid is obtained from the action of sulphu- ric acid on the iodate of barytes, made by causing bary- tic water to act on iodine. 31. Iodic acid, when pure, has a strong acid astrin- gent taste, but no smell. Its density is considerably greater than that of sulphuric acid. It melts, and is de- composed into iodine and oxygen, at a temperature of about 620°. It consists of 15.5 iodine, 5. oxygen. 32. Iodic acid deliquesces in the air, and is very solu- ble in water. It first reddens, and then destroys the blues of vegetable infusions. It blanches other vegetable col-. ours. It appears to form combinations with all the fluid or solid acids, which it does not decompose. 33. Hypophosphorous acid is obtained from the phos- phuret of barytes, by means of sulphuric acid. 34. It has a very sour taste, reddens vegetable blues, and does not crystallize. The hypophosphites have the property of being all soluble in water. The hypophos- phorous acid is probably composed of 2 primes of phos- phorus = 3. -j- 1 of oxygen. 35. Phosphorous acid is obtained from the action of phosphorus and corrosive sublimate, in an elevated tem- perature. In a liquid state it consists of 80.7 acid -f- 19.3 water. Its prime equivalent is 2.5. 36. It lias a very sour taste, reddens vegetable blues, and forms salts with the salifiable bases. When heated itrongly in open vessels, it inflames, phosphuretted hy-- drogen is evolved, and phosphoric acid remains. 1,72 WTRODUCTJON 37. Phosphoric acid abounds in the mineral, vegeta* hie and animal kingdoms. 38. Its general characters are ; it is soluble in water in all proportions. It produces heat when mixed with water. When pure, it has no smell, its taste is sour, but not corrosive. When perfectly dry it sublimes in close vessels. When considerably diluted with water and evaporated, the aqueous vapour carries up a small por- tion of the acid. With charcoal or inflammable matter, in a strong heat, it loses its oxygen and becomes con- verted into phosphorus. Its composition appears to be 100 phosphorus -f 134.5 oxygen, whence its equivalent is 3.500. 39. Phosphoric acid for general purposes is extract ed from bones, which are phosphate of lime ; when cal- cined, sulphuric acid is added to them in powder, a de- composition ensues, sulphuric acid combines with the lime, and the phosphoric acid is set at liberty. 40. Hyposulphurous acid has been obtained from a class of salts, formed by an acid of sulphur, having a proportion of oxygen less than that of sulphurous acid. Observation. Mr. Herschel mixed a diluted solution of hyposulphite of strontites, with a slight excess of diluted sulphuric acid, and after agitation, poured the mixture on three filtres. The first was received into a solution of r'arbonate of potash, from which it expelled carbonic acid gas. The second portion being received succes- sively into nitrates of silver and mercury, precipitated the metals copiously in the state of sulphurets, but pro- duced no effect on solutions of copper, iron or zinc.— The third, being tasted, was acid, astringent and bitter. When fresh filtered, it was clear, but became milky on standing, depositing sulphur, and coloured sulphuric acid. A moderate exposure to air or heat, caused its entire TO CHEMISTRY. 173 decomposition. The prime equivalent of this acid is found to be 59.25. It is composed of 20 sulphur -f 10 oxygen- 41. Hyposulphurous acid unites with alkalies and earths, forming compounds called hyposulphites. 42. Hyposulphuric acid is obtained by passing sulphu- rous acid gas over the black oxide of manganese ; a com- bination takes place, the excess of the oxide of manga- nese is separated by dissolving the hyposulphate of man- ganese in water. Caustic barytes precipitates the man- ganese and forms with the new acid a very soluble salt, which freed from the excess of barytes by a current of carbonic acid, crystallizes regularly.- To this salt in so- lution, sulphuric acid is cautiously added, which throws down the barytes, and leaves the hyposulphuric acid in the water. 43. It has the following properties. It is decompos- ed by heat into sulphurous and sulphuric acids. It forms soluble salts with strontites, barytes, lime, lead and sil- ver. The hyposulphates yield sulphurous acid, when their solutions are mixed with acids, if the mixture be- comes hot of itself or by artificial heat. They disengage a large quantity of sulphurous acid at an high tempera- ture, and are converted into neutral sulphates. It is composed of 8 sulphur -f- 10 oxygen. 44. Sulphurous acid may be obtained by heating sul- phuric acid with mercury, or bits of copper in a glass retort. Exp. Put two parts of sulphuric acid and one of mer- cury into a glass retort, and apply to it the heat of an Argand's lamp, the mixture effervesces, and throws off a gas, which should be received over mercury, this gas is sulphurous acid. 15* ;74 i ."lRODl CI luN 45. Suij.huri.ius acid in a state of gas is colourless and invisible. It is incapable of maintaining combustion, :md deleterious to animal life. It possesses a strong suf- focating odour; 100 cubic inches weigh about 68 grains. It? specific gravity, when compared with hydrogen, is as 30. to 1. It whitens many animal and vegetable sub- stances. 46. Water at 61° absorbs 33 times its volume, and when saturated, acquires the specific gravity of 1.6513 at 68°. 47. It is decomposed by hydrogen, carbon, and sul- phuretted hydrogen gas, when assisted by heat. It oxi- dizes iron and zinc. 48. It consists of sulphur 68 Oxygen 32 100 49. Sulphuric acid so named from its being prepared from sulphur, has been long known by the name of oil of vitriol, from its oily appearance, and vitriolic acid from its being first prepared from iron. 50. Sulphuric acid has a strong affinity for water, ?nd when combined with it, which is the state we meet within it, is properly an hydro sulphuric. 51. It is composed of sulphur, oxygen and water, and when good, its specific gravity should be 1.8485. 52. It is slightly viscid, transparent and colourless; destitute of smell, of a strong acid taste. When diluted with an equal weight of water,it freezes at — 38° F. and boils at 580°. It absorbs water rapidly from the atmos- phere. When water is mixed with it, the temperature is suddenly increased. Exp. Take a small quantity of water in one glass, and about twice as much by measure of sulphuric acid in TO CHEMISTRY. *76 another, let them both be of the common temperature of the atmosphere ; suddenly mix them, and the heat will be increased to the boiling point of water. Illustration The bulk of the two bodies when mixed is less than when they were in a separate state ; this ac- counts Tor the sudden extrication of caloric. 53. Diluted acid having a specific gravity of 1.6321, has suffered the greatest condensation ; 100 parts in bulk have become 92.14. If either more or less acid exist in the compound, the volume will be increased. The cause of the maximum condensation at this particular point of dilution is unknown. 54. Sulphuric acid is decomposed, when mixed with inflammable bodies. Exp. 1. If a piece of charcoal made red hot be im- mersed in common concentrated sulphuric acid, the acid will be decomposed and part of its oxygen is attracted by the charcoal forming carbonic acid, while part of the acid goes off in thick white fumes. Exp. 2. Phosphorus, with the aid of heat, decom- poses the sulphuric acid by absorbing a part of its oxy- gen. Exp. 3. Immerse bits of straw in this acid, they be- come black. Illustration. Vegetables are composed of carbon, hy- drogen and oxygen; the hydrogen of the vegetable com- bines with the oxygen of the acid, and leaves the straw in a carbonized state. 55. Sulphuric acid decomposes water, and the hy- drogen gas is evolved. Exp. Pour sulphuric acid diluted with water on some filings of iron or zinc, a violent action takes place ; the hydrogen of the water is disengaged in the form of gas, 176 INTRODUCTION" wh'le the oxygen cciiihhus with the metal and forms an oxide. 56. Sulphuric acid does not oxidize gold, platinum, tungsten, or titanium. 57. Sulphuric acid unites with all the alkalies and earths, except silica, and with many of the metallic ox- ides, forming a peculiar kind of salts, called sulphates. 58. Sulphuric acid, in its concentrated state, consists, in 100 parts, of 30 sulphur, 45 oxygen, 25 water. 59. It is employed in a variety of manufactures, in dyeing ; in medicine and pharmacy ; and is therefore of considerable importance. 60. Cyanic acid, hydrocyanic acid, is usually called prussic acid, and is an acid obtained from the beautiful blue pigment, -called Prussian blue, whi^h is a com- pound of prussic acid with iron and alumina. Exp. To a quantity of powdered prussian blue dif- fused in boiling water, let red oxide of mercury be ail- ed in successive portions, until the blue colour is de- stroyed. Filter the liquid and concentrate by evapora- tion, until a pellicle appears. On cooling, crystals of prussiate or cyanide of mercury will be formed. Dry these and put them into a tubulated glass retort, to the beak of which, is adopted a horizontal tube, about two feet long and fully half an inch wide at its middle part. The first third part of the tube next the retort is filled with small pieces of white marble, the two other thirds with fused muriate of lime. To the end of this tube is adopted a small receiver, which should be immersed in ice. Pour on the crystals, muriatic acid, in rather less quantity than is sufficient to saturate the oxide of mer- cury which formed them. Apply a very gentle heat to the retort. Hydrocyanic acid will be evolved in vapour, and will condense in the tube. If muriatic acid passes TC CHEMISTRY. 177 over, it will be obstructed by the marble, while the wa- ter will be absorbed by the muriate of lime. By means of a moderate heat applied to the tube, the acid may be made to pass successively along, and after being left sometime in contact with muriate of lime, it may be, finally, driven into the receiver. As the carbonic acid evolved from the marble by the muriatic is apt to carry off some of the prussic acid, care should be taken in con- ducting the distillation. 61. Prussic acid is a colourless liquid, possessing a strong odour of peach blossoms ; when snuffed up the nose, it may produce sickness, or fainting. Its taste is cooling at first, then hot, and operates as a most virulent poison, producing almost instant death on animals. Its specific gravity at 44^° is 0.7058 ; at 64° it is 0.6969.— It boils at 8If and congeals at about 3°. It then crys- tallizes regularly, sometimes in the fibrous form of ni- trate of ammonia. The cold which it produces, when reduced to vapour, even at the temperature of 68°, is sufficient to congeal it. Exp. Put a small drop on a piece of glass tube or slip of paper, it will become solid. 62. The specific gravity of its vapour, experimentally compared, to that of air, is 0.9476 to 1.0000. By calcu- lation from its constituents, it is 0.9360. 03. The small density of prussic acid compared with its great volatility, furnishes a proof that the density of vapours does not depend upon the boiling point of the liquids that furnish them, but upon their peculiar con- stitution. 64. This acid, when procured for experiment or me- dicinal purposes, must be made use of as soon as possi- ble, as it cannot be preserved, even in close stopped phial', for any length of time, without decomposition, 178 INTRODUCTION 65. Prussic acid has a strong affinity for metallic ox- ides, and precipitates the solution of iron m acids, of a blue colour, which is called Prussian blue. 66. To form Prussian blue, the peroxide of iron should be used, as the protoxide produces a pale blue colour, which will not be deep or permanent, Unless ex- posed for some time to the air, whence it imbibes oxy- gen. Exp. Take a solution of green sulphate of iron, and add to it a solution of prussiate of potash, a dirty green precipitate will be formed, which, on exposure to the air, assumes a pale blue colour. If we now pour nitrous acid upon it, the Prussian blue colour will be immedi- ately produced, as the acid yields its oxygen to the pre. cipitate. 67. Prussic acid is composed of hydrogen, nitrogen and carbon ; not a trace of oxygen has ever been found in it. PRACTICAL QUESTIONS. What is muriatic acid ? What are the properties of the gas ? Of what does it consist ? Has it any affinity for water ? What is the colour of a solution of this gas ? What is the cause of the colour ? What is its specific gravity ? When is the liquid acid capable of existing ? When it contains 48 per cent of the acid gas, what is its specific gravity ? What is its boiling point ? What phenomena attend the boiling of this acid ? With what does it combine and form ? What a:-c muriates ? TO CHEMISTRY 179 What is chloric acid ? How do you form it ? What are its properties ? How is it decomposed ? What does it form with the alkalies and earths ? How is perchloric acid obtained ? Of what is chloro-carbonous acid composed ? What are its properties ? • What is the opinion of Thcnard with regard to its composition ? What is nitrous acid ? Of what is it composed ? Of what is nitric acid composed ? How do you prove it synthetically and analytically ? What is the cause of its corrosive and burning quality ? What are the properties of nitric acid ? Why does it oxidate metals ? How is it obtained ? What does it form with earths and alkalies $ How is iodic acid obtained ? What are its properties ? What effect does the air and water have upon it, and how does it effect vegetable colours ? How is hypophosphorous acid obtained ? What are its properties ? How is phosphorous acid obtained ? What are its properties ? Where is phosphoric acid found ? What are its characters-? How is it obtained ? How is hyposulphurous acid obtained ? How did Mr. Herschell obtain it ? Does it unite with salifiable bases ? How is hyposulphuric acid obtained*? 180 INTRODUCTION What are its properties ? How can sulphurous acid be obtained ? What are its properties ? How much will water absorb ? What will decompose it ? Of what does it consist ? What is sulphuric acid ? Has sulphuric acid any affinity for water ? Of what is it composed ? What are its properties ? Why is caloric extricated when this acid is mixed with water ? Why does it turn wood black ? When added in a diluted state to iron filings, what is decomposed ? What does it form with the alkalies, earths and metal- lic oxides ? Of what does it consist ? Is it much used ? What is cyanic acid, or hydrocyanic acid 1 How do you form it ? What are its characteristics ? What is the specific gravity of its vapour ? What proof does its small density furnish ? Is it easily decomposed ? Has it any affinity for metallic oxides ? What should be used to form Prussian blue ? Of what is it composed ? TO CHEMISTRY. 181 CHAP. XVIII. Of Oxygen Acids—Metallic. 1. Arsenic acid is formed from a metal called arse- nic. 2. It is obtained from the white substance called arse- nic of the shops, which is the oxide of arsenic, by heat- ing it with nitric acid. 3. It does not crystallize, but attracts the moisture of the air, has a sharp caustic taste, reddens blue vegeta- ble colours, is fixed in the fire, and is a violent poison. Its specific gravity is 3.391. It appears to consist of 100 metal, and from 52 to 53 oxygen. 4. Combustible substances decompose this acid. Exp. If two parts of arsenic acid be mixed with one of charcoal, the mixture introduced into a glass retort, coated, and a matrass adopted to it, and the retort then gradually heated in a reverberatory furnace till the bot- tom is red ; the mass will be violently inflamed, and the acid reduced and rise to the neck of the retort in the metallic state, mixed with a little oxide and charcoal powder; a few drops of water will be found in the re- ceiver. 5. The arsenic acid combines with the earthy and al- kaline bases, forming salts, called arseniates; they are decomposable by charcoal, which separates the arsenic from them by means of heat. 6. Arsenic acid does not act on gold or platinum, nor on mercury or silver, without the aid of a strong heat; but it oxidizes copper, iron, lead, tin, zinc, bismuth, an- timony, cobalt, nickel, manganese, and arsenic. 7. Arsenious acid is the white arsenic of the shops, which is a compound of the metal with oxygen. 16 1"82 INTRODUCTION 8. It is a most virulent poison. It reddens some of ihe blue vegetable colours, and turns the syrup of violets green. When thrown on burning coals, it emits white fumes, which have a strong smell of garlic. It is acted upon by hydrogen and carbon, which deprive it of its oxygen at a red heat, and reduce the metal; the former forming water, the latter carbonic acid, with the oxy- gen. 9. Its specific gravity is 3.7. It is composed of metal 9.5. oxygen -f- 3. Its prime equivalent is 12.5. 10. It is soluble in thirteen times its weight of boil- ing water, but requires eighty times its weight of cold. Exp. When a mixture of arsenious acid with quick- lime is heated in a glass tube, at a certain temperature, ignition suddenly pervades the whole mass, and metallic arsenic sublimes. As arseniate of lime is found at the bottom of the tube, we infer that a portion of the arse- nious acid is robbed of its oxygen to complete the acidi- fication of the rest. 11. Arsenious acid is used in numerous instances in the arts, and some in medicine. It has lately been used as an alterative, with advantage, in chronic rheumatism. 12. Antimonious acid is obtained from the metal of that name, and is the tritoxide, or third degree of oxy- genation of the metal, by immediate combustion. It was formerly called, from its white appearance, argentine flowers of antimony. It may also be formed by digesting hot nitric acid on the metal. 13. Antimonious acid when fused with one fourth of antimony, loses one portion of its oxygen, and is con- verted into the deutoxide of antimony. 14. Antimonious acid forms salts with different bases, called antimonites. TO CHEMISTRY. 183 15. tt consists of 78.6 antimony, and -f- 21.4 oxygen^ 16. Antimonic acid is the peroxide of antimony. 17. It is formed when the metal in powder is ignited with six times its weight of nitre in a silver crucible.— The excess of potash and nitre being afterwards sepa- rated with hot water, the antimoniate of potash is then to be decomposed by muriatic acid, when the antimonic acid, of a straw colour, will be obtained. 18. It is insoluble in water, but reddens vegetable blues. It does not combine with acids. At a red heat, oxygen is disengaged, and antimonious acid is produced. 19. Chromic acid has been obtained from the chro- mate of lead, or the red lead ore of Siberia, and from the chromate of iron, an abundance of which, exists near Baltimore, in Maryland. The acid is the tritoxide of chrome. 20. It is soluble in water, and crystallizes by cooling and evaporation, in long prisms of a ruby red. Its taste is acrid and styptic. Its specific gravity is not exactly known, but it always exceeds that of water. It power- fully reddens the tincture of turnsole. 21. The chromic acid readily unites with alkalies, and is the only acid that has the property of colouring its salts. The salts are called chromates. 22. Chromic acid causes different coloured precipi- tates-with the metallic oxides. Exp. 1. Precipitate mercury from its-solution in ni- tric acid, by chromic acid, a dark cinnabar coloured sub- stance will be thrown down. Exp. 2. Add chromic acid to a solution of nitrate of silver, a precipitate is formed, which, at first is of a beautiful carmine, but becomes purple by exposure to light. 184 INTRODUCTION Exp. 3. With nitrate of copper, it gives a chesnut red precipitate. Exp. 4. With solutions of sulphate of zinc, muriate of bismuth, muriate of antimony, nitrate of nickel, and muriate of platina, chromic acid produces yellowish pre- cipitates. Exp. 5. With muriate of gold, it produces a greenish precipitate. Exp. 6. If paper be impregnated with the acid and exposed to the sun a few days, it assumes a green col- our, which remains permanent in the dark. 23. Columbic acid is an acid obtained from a metal called columbium, or tantalium, or yttro-tantalite. 24. It is in the form of a white powder, which is in- soluble in nitric and sulphuric acids, but partially in mu- riatic. 25. It forms with barytes an insoluble salt. Its pro- portions are inferred to be 100 metal, and 5.485 oxy- gen. 26. Molybdic acid is a substance obtained from the metal, called Molybdenum. 27. It changes vegetable bhies to red ; unites with the alkalies, forming salts, called molybdates, and pre- cipitates the metals from their solutions. Its specific gravity is 3.460; and its prime equivalent is 9, consisting of 3 of oxygen -f- 6 of metal. 28. Molybdous acid is the deutoxide of molybdenum. It is of a blue colour, and possesses acid properties. It reddens vegetable blues, and forms salts with the bases. 29. Air or water when left to act sometime on the metal, convert it into this acid. 30. It consists of 100 metal, and 34 oxygen, nearly. 31. Tungstic acid has been found only in two mine- rals, the one formerly called tungsten, tungstate of lime, TO CHEMISTRY. 185 the other is composed of tungstic acid, Oxide of iron, and a little oxide of manganese, called Wolfram. 32. The tungstic acid is tasteless and does not rerf.ien vegetable blues. It unites and forms salts with the bases, such as earths, alkalies, and metallic oxides. 33. It is composed of 100 parts metallic tungsten. and 25, or 26.4 oxygen. PRACTICAL QUESTIONS. How is arsenic acid obtained ? What are its properties ? What effect have combustible substances on this acid? With what does it combine ? Does it act on the metals ? What is arsenious acid ? What are its properties ? What is its specific gravity ? What is its solubility ? Is arsenious acid of much use ? How is antimonious acid obtained ? What phenomena does it exhibit when fused ? What does it form ? Of what does it consist ? What is antimonic acid ? How is it formed ? What are its properties ? Of what is it composed ? From what has chromic acid been obtained •? What are its properties ? Does it unite with alkalies ? What effect does it have on metallic oxides 7 What is columbic acid ? What are its characteristics ? What is molybdic acid ? 16* 186 INTRODUCTION What are its characteristics ? What is molybdous acid ? What effect have air and water on the metal Of what does it consist ? Where has tungstic acid been found ? What are its characteristics ? Of what is it composed ? CHAP. XIX. Continuation of Acids.—Hydrogen Acids. 1. Fluoric acid is obtained from the fluate of lime^ known by the name of Derbyshire spar, or fluor spar, a name acquired from the circumstance of its being used to render the ores of metals more fluid, when fused. 2. The spar has been long known, and in use for a variety of ornamental and other purposes ; but its real nature was not ascertained until Scheele discovered that it consisted of lime, united with a peculiar acid, which has obtained the name of fluoric acid. 3. It may be prepared by placing powdered fluor spar in a retort of lead or silver, with a receiver of the same metal adopted, if its weight of sulphuric acid be then poured upon it, the fluoric acid will be disengaged by the application of a moderate heat 4. This acid gas readily combines with water, for which purpose it is necessary that the receiver should be half filled with that fluid. 5. When the receiver is surrounded with pounded ice, and no water put into it, the acid condensed is an in- tensely active fluid. It has the appearance of sulphuric TO CHEMISTRY. 187 acid, but is much more volatile, and emits white fumes when exposed to the air. Its specific gravity is only 1.0000. When applied to the skin, it instantly corrodes it, and produces wounds very difficult to heal. When potassium is introduced into it, it acts with intense ener- gy, and produces hydrogen gas and a neutral salt. When lime is made to act upon it, a violent heat is excited, water is formed, and the same substance as fluor spar i6 produced. With water in a certain proportion, its densi- ty is increased to 1.25. When it is dropped into water, a hissing noise is perceived, with much heat, and an acid fluid, not disagreeable to the taste, is formed, if the wa- ter be in sufficient quantity. It instantly corrodes and dissolves glass, in consequence of its great affinity for silex. Exp. Coat a piece of common window glass with wax, and then .with a pin draw any figures on it you please, by scratching the wax through to the glass; pour over it fluoric acid, and it will corrode the glass only where the wax has been removed, and produce a repre- sentation similar to an engraving. Or the glass may be placed on a cup containing the sulphuric acid and fluor spar ; the cup placed in a temperature of 212°, the gas which arises will corrode equally as well, as the liquid acid. 6. Fluoric acid is regarded as a compound of hydro- gen, and a principle which acts the part of an acidifier, and which is found only in the fluates, called fluorine. 7. Hydriodic acid resembles the muriatic in being gaseous in its insulated state. 8. It may be prepared in the following manner.— Mix 4 parts of iodine with one of phosphorus, in a small glass retort, apply a gentle heat, and add a few drops of water from time to time, a gas comes over, which must 188 INTRODUCTION be received over mercury ; or it may be condensed with water in the same manner as muriatic acid. 9. In the state of gas, its specific gravity is 4.4} 100 cubic inches weigh 134.2 grains. It is elastic and invisi- ble, but has a smell somewhat similar to muriatic acid. It is composed of iodine and hydrogen, by weight 8.61 iodine, 0.0694 hydrogen. 10. Hydriodic acid is paitly decomposed at a red heat, and its decomposition is complete; if oxygen be present, water is formed, and iodine separated. 11. Ferroprussic acid is obtained in the following manner. Into a solution of what is usually called prus- siate of potash, pour hydrosulphuret of barytes as long as any preceipitate forms. Throw the whole on a filtre, and wash it with cold water. Dry it,.and having dis- solved 100 parts in cold water, add gradually 30 of con- centrated sulphuric acid, agitate the mixture, and set it aside until the liquor becomes clear; this is ferroprussic acid, or ferruretted cbsyazic acid. 12. It has a pale lemon yellow colour, but no smell. Heat and light decompose it. Hydrocyanic acid is then formed, and white ferroprussiate of iron, which soon be- comes blue. 13* Its affinity for the salifiable bases enables it to displace acetic acid without beat from the acetates, and to form ferroprussiates. 14. The base of this acid is prussine, or that which generates blue, which is united to hydrogen as its acidi- ■fier. 15. Hydrosulpkurous acid is sulphurous acid combined. with hydrogen. 16. Hydrotelhrric acid is a combination-of tellurium with hydrogen. It combines with the alkalies. Its smell is very strong and peculiar. TO CHEMISTRY.. 189 17. Sulphur op russic acid, or sulphuretted chyazic acid is a transparent and colourless liquid, possessing a strong odour, somewhat resembling acetic acid. Its specific gravity is 1.022. It dissolves a little sulphur at a boil- ing heat, it then blackens nitrate of silver, but the pure acid throws down the silver white. By repeated distil- lations, the sulphur is separated, and the acid decompos- ed. 18. It combines with the earths and alkalies, and forms salts, called sulphwoprussiates. ACIDS WITHOUT OXYGEN OR HYDROGEN. 19. Chloriodic acid was formed, by Sir H. Davy, by admitting chlorine in excess to known quantities of io- dine, in vessels exhausted of air, and repeatedly heating the sublimate. Operating in this way, he found that io- dine absorbed less than one third of its weight of chlo- rine. 20. It is of a bright yellow colour ; when fused, it becomes of a deep orange, and when rendered elastic, it forms a deep orange coloured gas. It is capable of combining with much iodine, when they are heated to- gether ; its colour becomes in consequence deeper, and the chloriodic acid and the iodine rise together in the elastic state. 21. A triple compound of this acid and sodium may exist, according to Sir H. Davy, in sea water,, and in common soot. 22. Chloro-prussic acid, or chloro-cyanic acid, was formerly called oxy-prussic acid; it is found,, however, not to contain oxygen, but is a compound of chlorine and prussic acid. 23. When hydro-cyanic acid is mixed with chlorine* it acquires new properties. Its odour is much increase 190 INTRODUCTION ed. It no longer forms Prussian blue with solutions of iron, but a green precipitate, which becomes blue by the addition of sulphurous acid. 24. It consists, according to M. Gay Lussac, of equal volumes of chlorine and prussine, or the base of the prussic acid.. 25. Fluoboric acid is obtained from fluor spar and vi- treous boracic acid, by mixing together one parf boracic acid, two fluor spar, and twelve oil of vitriol, and distil ling, in a glass retort. It is obtained in the form of gas. 26. 100 cubic inches of this gas weigh 78.5 grains. Its density is to that of ah* as 2.371 to 1.000. It is col- ourless, its smell is pungent, resembling that of muriatic. acid. It will not support respiration or combustion. It reddens strongly the tincture of turnsole. It attacks vio- lently animal and vegetable substances. Exposed to a high temperature, it is not decomposed. It is condensed by cold without changing its form. When it is put in contact with oxygen or air, it suffers no change, except seizing, at ordinary temperatures, the water which they contain, and becomes a liquid, emitting extremely dense fumes. It operates in the same way with all the gases, which contain moisture. However little they may con- tain, it occasions in them very perceptible vapours. 27. Fluoboric acid gas is very soluble in water. It can combine, according to Dr. Davy, with 700 times its- own volume, or twice its weight at the ordinary tem- perature and pressure of the atmosphere. The liquid has a specific gravity of 1.770. 28. Fluo-silicic acid is a combination of fluorine with silicon. It contains in 100 parts 61.4 silicon. Exp. If the mixture of fluor spar and sulphuric acid be distilled in glass vessels, the glass would be acted up- TO CHEMISTKV. 191! on, and a peculiar gaseous subsiance be produced, which fliust be collected over mercury. 29. This gas is very heavy, 100 cubic inches of it weighs 110.77 grains ; its specific gravity is to that of air as 3.632 to 1.000. It is about 48 times denser than hydrogen. When brought into contact with water, it instantly dcposites a gelatinous substance,which is hydrate of silica. It produces white fumes when suffered to pass into the atmosphere. It is not affected by any of the common combustible bodies; but when potassium is strongly heated in it, it takes fire and burns with a deep red light, the gas is absorbed, and a rose coloured sub- stance is formed, which yields alkali to water, with slight effervescence, and contains a combustible body. PRACTICAL QUESTIONS. How is fluoric acid obtained ? Who ascertained the real nature of fluor spar ? How may fluoric acid be prepared ? What are its properties ? What is fluoric acid considered to be 4 What does hydriodic acid resemble 1 How may it be prepared ? What are its characteristics 7 How is it decomposed ? How is ferroprussic acid obtained ? What are its characteristics 1 What enables it to displace acetic acid 1 What is its composition ? What is hydrosulphurous acid ? What is hydrotellurous acid ? What is sulphuroprussic acid? With what does it combine ? What is chloriodic acid ? 192 INTRODUCTION What are its characteristics ? Where may a triple compound of this acid and sodioti exist ? What is chloroprussic acid ? What is the effect when hydrocyanic acid is mixed with chlorine ? Of what does it consist ? From what is fluoboric acid obtained ? What are its characteristics ? Is it soluble in water ? What is fluosilicic acid ? What is its weight and properties ? CHAP. XX. Acids of organic origin. \. Acids of organic origin are those obtained from animal and vegetable substances. Those which have hitherto been discovered, amount to thirty-eight. 2. Aceric acid is a peculiar acid, said to exist in the juice of the maple, {acer saccharinum.) It is decompos- ed by heat, like the other vegetable acids. 3. Acetic acid is the same acid, which, in a diluted state, is called vinegar, and formerly acetous acid. 4. This acid is found combined with potash in the juice of many plants. It is the result, likewise, of spon- taneous fermentation, to which liquid, vegetable and ani- mal matters are liable. b. The varieties of acetic acid known in commerce, are four. 1. Wine vinegar. 2. Malt vinegar, or that obtained from beer. 3 Sugar vinegar, or the result of TO CHEMISTRY. 193 the acetic fermentation of saccharine solutions. 4. Wood vinegar or pyroligneous acid. 6. Acetic acid enters into combination with the salifi- able bases, and forms substances called acetates. 7. They are characterized by the pungent smell of vinegar which they exhale on mixing them with sulphur- ic acid. They are all soluble in water; many of them cannot be crystallized. About 30 different acetates have been formed. 8. Acetic acid when highly concentrated is pungent and acrid, and corrodes animal substances. 9. Amniotic acid is obtained from the liquor amnii of the cow, by evaporation and crystallization. 10. These crystals when washed in cold water, are white and shining, slightly acid to the taste, redden lit- mus paper, and are a little more soluble in hot than cold water. They are likewise soluble in alcohol. This acid forms with the alkalies, very soluble salts. When thrown on burning coals the crystals of the acid swell? turn black, give out ammonia and prussic acid, and leave a bulky coal. 11. Benzoic acid was so named because it was first obtained from the resin of benzoin. It is found in a va- riety of substances. If we concentrate the urine of hors- es and cows, and pour muriatic acid on the mass, a copi. ■ous precipitate of benzoic acid will be formed. It is us- ed in medicine under the name of flowers of Benja- min. 12. Benzoic acid is a very fine, light substance, in ■needle-form crystals. It combines with alkalies, earths and metallic oxides, forming benzoates. It is soluble in boiling water, and also in alcohol, in the latter case it is precipitated by the addition of water. 13. Boletic acid is extracted from the expressed juice 17 194 INTRODUCTION of the boletus pseudo-igniarius, a species of mushroom 14. Boletic acid, when properly prepared, consists of crystals of irregular four sided prisms, of a white colour, permanent in the air. Its taste resembles cream of tar- tar. At the temperature of 68° it dissolves in 180 times its weight of water, and in 45 of akohol. It red- dens vegetable blues. It precipitates the red oxide of iron, and the oxides of silver from their solutions in nitric acid. it sublimes, when heated, in white vapours, and is con. densed into a white powder. 15. Camphoric acid is obtained from camphor, by distilling it with nitric acid, it is in the shape of crys- tals. 16. These are in the form of parallelopipedons, but of so delicate a structure, that they efflorecse in the air. They are of a slightly acid taste, and redden vegetable blues. The acid forms camphorates with alkalies, earths and metallic oxides, 17. Caseic acid is the name given to the acid found in cheese to which the flavour has been ascribed. 18. The citric acid is obtained from the juice of lem- ons and limes ; it is also found in several other fruits. 19. It crystallizes in "beautiful prisms, is extremely acid and very soluble in water. It combines with the earths and metallic oxides, forming salts called citrates. 20. It is much used in calico printing, and in medi- cine. 21. Formic acid is obtained from ants, either by dis- tillation or infusion in boiling water. 22. It has a very sour taste, and continues liquid at a low temperature. Its specific gravity is 1.1158 at 68°. It has been used by quacks as a remedy for the tooth- ache. 23. Fungic acid ie obtained from severaFspecies of mushrooms. TO CHEMISTRY. 195 24. It is a colourless,uncry stallizable and deliquescent mass, of a very sour taste. It precipitates from a solution of acetate of lead,a flocculant mass which is soluble in dis- tilled vinegar. It unites with alkalies and earths, and forms salts called fungates. 25. Gallic acid is obtained from nutgalls, and from the bark of other trees in which the astringent principle re- sides. 26. Its most distinguishing characteristic is its great affinity for metallic oxides, so, as when combined with tannin, to take them from powerful acids. The more readily the metals part with their oxygen, the easier they are alterable by gallic acid. Exp. To a solution of Gold, gallic acid imparts a green hue, and a- brown precipitate is formed, which readily passes to the metallic state, and covers the solu- tion with a shining golden pellicle. A similar effect is produced with a solution of nitrate of silver.. Mercury is precipitated of an orange colour, copper brown; bis- muth of a brown colour ; lead, white ; iron, black. 27. The gallic acid is of extensive use in dying, as it constitutes one of the principal ingredients in all the shades of black, and is employed to fix or improve sev- eral other colours. It is a well known ingredient in ink. 23. Kinic acid is a peculiar acid obtained from cin- chona, or Jesuit's bark ; when concentrated it yields reg- ular crystals. 29. It is decomposed by heat, while it forms a solu- ble salt with limo, it does not precipitate silver or lead from their solutions. 3"). Lacc'c acid is obtained from a substance called Stick Lac. 31. It crystallizes, has a wine yellow colour, has an 196 INTRODUCTION acid taste, and is soluble in water, alcohol and ether It precipitates lead and mercury white ; but it does not affect lime, barytes or silver in their solutions. It throws down the salts of iron white. With lime, soda, and potash, it forms deliquescent salts soluble in alcohol. 32. Lactic acid is obtained from sour whey or iniik. 33. When pure, it ha3 a brown yellow colour and a sharp sour taste, which is much weakened by diluting it with water. It ie without smell in the cold, but emits when heated, a sharp sour odour. It cannot be made to crystallize, and does not exhibit the slightest appearance of a saline substance, but dries into a thick and smooth varnish, which slowly attracts moisture from the air. It is very easily soluble in alcohol. With earths, alkalies and metallic oxides it affords peculiar salts, and those are distinguished by being soluble in alcohol, and drying into 1 mass like gum, which slowly becomes moist in the ot, mosphere, 34. Lampic acid is formed from the slow combustion of ether. 35. Lampic acid, when first procured, is a colourless fluid of an intensely sour taste and pungent smell. Its va- pour, when heated, is extremely irritating and disagree- able. Its specific gravity varies according to the care with which it has been procured, from less than 1.000 to 1.008. It unites with alkalies, earths and metallic oxides, forming compounds called lampates. 36. Lithic acid was discovered about the year 1776, by Mr. Scheele. in analyzing the human calculi, in many of which it constitutes a greater part, and in some it forms almost the whole, it is often called uric acid. 37. Its colour is yellow, and it has a cool, bitter taste. It dissolves readily in water and in alkaline solutions, TO CHEMISTRY. 197 from which it is not precipitated by acids. It is sp-rlng- ly soluble in alcohol. It combines with alkalies and earths, forming salts called lithatcs. 38. Malic acid, is that taken from apples, and appears to be the same as the sorbic acid. 39. Meconic acid is a constituent of opium, and is pre- pared from that drug. 40. It has a strong sour taste, which leaves behind it an impression of bitterness. It dissolves readily in water alcohol and ether. Reddens vegetable blues, and chan- ges the solution of iron to a cherry red colour. It unites with the alkalies and forms compounds called maconiatcs. Mcnispermic acid is obtained from the seed of the me- nispermum cocculus. 42. It occasions no precipitate with lime water, with nitrate of barytes it yields a grey precipitate; with ni- trate of silver it yields a deep yellow; and with sulphate of magnesia a copious precipitate. 43. Mar gar ic acid is an acid obtained from soap made of pork grease, and potash. It is procured in the form of pearly white crystals. 44. It has no taste. Its smell is feeble, a little resem bling that of melted wax. Its specific gravity is inferior to water. It melts at 131° F. into a very limpid colourless liquid, which crystallizes on cooling, into brilliant crys- tals of the purest white. It is insoluble in w-ter, but very soluble in alcohol. Specific gravity 0.800. Cold margaric acid has no action on litmus when cold, but when heated so as to soften without melting, the blue is redden- ed. It combines with the salifiable bases and forms neu- tral compounds called margarates. 45. Melascic acid is that which at present is procur ed from Molasses, which is thought to be a peculiar acid' by some. 17* 198 l.MRODUCTlu.N 46. Mellitic acid is obtained from the Mvlliic, or hon- ey stone, and is thought to be of vegetable origin. 47. It crystallizes in fine needles,or small prisms. Its taste is at first of a sweetish sour, which is followed by a bitterness. On a plate of hot metal it is readily decom- posed and dissipated in copious grey fumes, leaving be- hind a small quantity of ashes, that do not change either red or blue litmus. It unites with some of the alkalies and forms mcllitatcs. 48. Moroxylic acid was obtained from a while sub- stance found on the bark of the white mulberry, growing ia the botanic garden of Palermo. It is considered as re- sembling nearly the succinic acid, but its characters have not been fully examined. 49. Mucic acid was formerly called saccholactic acid, because it was obtained from sugar of milk ; but as all the gums appear to afford it, and the principal acid in the sugar of milk is oxalic, it is, in general, distinguished by the name of music acid. 50. It is obtained from gum in the form of a pulverulent mass. It is soluble in about 60parts of hot water, and by cooling, a fourth part separates in the form of scales that grow white in the air. It decomposes the muriate of barytes and both the nitrate and muriate of lime. It forms with the metallic oxides, salts scarcely soluble. It precipitates the nitrates of silver, lead and mercury. It consists, according to Berzelius, of Hydrogen, 5.115 Carbon, 33.430 Oxygen, 61.465 100.000 51. Oleic acid is obtained from hog's lard*. 52. It is an oily fluid without taste or smell Its spe- TO CHEMISTRY. 199 chic gravity is 0.914. It is generally soluble in its own weight of boiling alcohol, of the specific gravity 0.7952. 100 of the oleic acid saturates 16.58 of potash; 10.11 of soda, 7.52 of magnesia, 14.83 of zinc, and 13.93 of pro- toxide of copper. 53. Oxalic acid is the acid which abounds in wood sorrel, and which, combined with a small portion of pot ash which exists in that plant, has been sold under the name of salt of lemons. It is obtained in quantities from sugar. 51. This acid exists in the form of crystals; they have a strong acid taste, and act powerfully on vegetable col- ours. The acidity is so great, that when dissolved in 3600 times their weight of water, it reddens litmus pa- per. These crystals dissolve in twice their weight of water. They effloresce in the air. It combines with earths, alkalies and metallic oxides, and forms salts, known by the name of oxalates. It is capable of oxidiz- ing lead, copper, iron, Lc. It has a great affinity for iron ; on this principle it is employed for removing ink spots from linen. It is used as a test to detect the exis- tence of lime in solution. Exp. Drop a little of the acid into water supposed to contain lime ; if there be any, a white powder is imme- diately precipitated. 55. Purpuric acid is found in some of the urinary calculi. 56. It usually exists in the form of a very fine pow- der, of a slightly yellowish, or cream colour. It pos- sesses no smell or taste. Its specific gravity is greater than that of water. It is scarcely soluble in water. One tenth of a grain boiled in 1000 grains of water, was not entirely dissolved. The water, however, assumed a 200 iNTRom/cnoN 1 purple tint. It is insoluble in alcohol or eiko/ It unites with the alkalies, and forms purpurates. 57. Pvrolilhic acid is obtained from uric acid concre- tions, by distillation. 53. It is obtained in the shape of acicular crystals.— They are soluble in four parts of cold water, and the so- lution reddens vegetables blues. Boiling alcohol dis- solves the acid, but on cooling, it deposits it in fine white grains. Nitric acid dissolves it without changing it. At a red heat it is decomposed. 100 parts consist of Oxygen 41.32 Carbon 28.29 Azote 16.84 Hydrogen 10. 99.15 59. Pyromalic acid is obtained from malic or sorbic acid, by distillation ; when pure, it is in the form of crystals. 60. These crystals are permanent in the air, they melt at 118° F. and on cooling, they form a pearl colour- ed mass of diverging needles, when thrown on coals they evaporate, and the smoke produces cough. Expos- ed to a low heat in a retort, they are partly sublimed in needles and are partly decomposed. They are very so- luble in strong alcohol and in double their weight of wa- ter at ordinary temperatures. The solution reddens vegetable blues, and forms with alkalies neutral salts, called pyromalates. 61. Pyrotartaric acid is obtained from tartar, by dis- tillation. The word pyro, signifying when prefixed to the name of an acid, that it is prepared by heat. 62. It has a very sour taste, and reddens powerfully the tincture of turnsole. Heated in an open vessel, the TO CHEMISTRY. 201 acid rises in a white smoke. It is very soluble in water, from which it is separated in crystals by evaporation. It combines with the salifiable bases, forming pyrotartrates. 63. Rosacic acid, an acid obtained from the sediment found in the urine of persons, labouring under intermit- tent fevers. This sediment is of a rose colour, occa- sionally in reddish crystals. 64. This acid is solid, of a lively cinnabar colour, without smell, with a faint taste, but reddening litmus very sensibly. On burning coals, it is decomposed into a pungent vapour. It is very soluble in water, and even attracts humidity from the atmosphere. It is soluble in alcohol, and combines with the salifiable bases. 65. Sebacic acid is obtained from hog's lard ; it is in the form of crystals of small white needles. 66. It is inodorous, of a slight taste, but it percepti- bly reddens litmus paper. Its specific gravity is greater than that of water. Exposed to heat, it i* decomposed, melts like fat, and is partially evaporated. The air has no effect upon it. Alcohol dissolves it abundantly at ordinary temperatures. It unites with the alkalies, and forms salts. 67. Sorbic acid is obtained from the berries of the mountain ash, sorbus, or pyrus aucuparia. It appears that sorbic and pure malic acids are the same. 68. It unites with the alkalies, and forms salts called sorbaies. 69. Suberic acid is obtained from cork, by means of nitric acid. 70. When pure, it is white and pulverulent, having a feeble taste and little action on litmus. It is soluble in 80 parts of water at 551°, and in 38 parts at 140«. \t is more soluble in alcohol, from which water throws down 202 IN 1RODUCTION a portion of the suberic acid. It unites with the alka- line bases, and forms suberates. 71. Succinic acid is obtained from amber by sublima- tion. It is, when pure, in white transparent crystals of a prismatic form. Their taste is somewhat sharp, and they redden powerfully tincture of turnsole. Heat melts and partially decomposes succinic aeid. Air has no ef- fect upon it It is soluble in both water and alcohol. It forms salts with the earths and alkalies, called succinates. 72.. Sulphovinic acid is a name given to a class of acids, which may be obtained by digesting alcohol and sulphuric acid together, with heat. It seems probable, that this acid is the hyposulphuric combined with a pe- culiar oily matter. 73. Tartaric acid is an acid obtained from tartar, which is a hard substance, adhering to the casks in which wine is kept. It may be procured in needle or laminat- ed crystals, by evaporation. 74. Its taste is extremely sour and agreeable ; it is often used in making punch, instead of lemon juice. It is very soluble in water. Burnt in an open fire, it leaves a coaly residuum ; in close vessels, it gives out carbonic acid, and carburetted hydrogen gas. By distilling nitric acid off the crystals, they may be converted into oxalic acid, and the nitric acid passes to the state of nitrous.— It unites with the salifiable bases and forms tartrates. 75. Zumic acid is obtained from sour rice, putrefied juice of beet roots, from the sour decoction of carrots, peas, &c. 76. It is without colour, docs not crystallize, has a very acid taste. It forms with alumina a substance re- sembling gum, and with magnesia, one unalterable in the air, in little granular crystals, soluble in 25 parts of TO CHEMISTRY. 203 water at 66° F. It forms salts, possessing peculiar cha- racteristics, with the other salifia'jl* bases, PRACTICAL QUESTIONS. What are acids of organic origin ? What is acetic acid ? Where is it found ? What are the varieties of acetic acid ? What are acetates ? How are they characterized ? How is acetic acid when highly concentrated ? From what is amniotic acid obtained ? What are its characteristics ? What is Benzoic acid ? What are its characteristics 1 From what is boletic acid obtained ? What are its characteristics ? What is camphoric acid ? What are its characteristics"? What is caseic acid ? What is the citric acid ? What are its characteristics ? Js it much used ? From what is formic acid obtained ? What are its properties ? From what is fungic acid obtained ? What are its characteristics ? From what is gallic acid obtained ? What are its characteristics ? Is it much used ? What is kinic acid ? What are its properties * From what is laccic acid obtained ? What are its properties ? 204* INTRODUCTION From what is lactic acid obtained ? What are its properties ? What is lampic acid ? What are its properties 1 What is lithic acid ? What are its characteristics ? What is malic acid ? What is meconic acid ? What are its characteristics ? What is menispermic acid? What are its properties ? What is margaric acid ? What are its properties ? What is melassic acid ? From what is mellitic acid obtained ? What are its properties ? From what is moroxylic acid obtained ? What is mucic acid ? What are its properties ? What is oleic acid ? What are its properties ? What is oxalic acid ? What are its characteristics? What is purpuric acid ? What are its characteristics ? From what is pyrolithic acid obtained ? What are its characteristics ? How is pyromalic acid obtained ? What are its properties ? From what is pyrotartaric acid obtained ! What are its characteristics ? What is rosacic acid ? What are its characteristics ? From what is sebacic acid obtained ' T© CHEMISTRY. 205 What are its characteristics ? What is sorbic acid ? From what is suberic acid obtained? What are its characteristics ? What is succinic acid ? What is sulphovinic acid ? What is tartaric acid ? What are its characteristics ? From what is zumic acid obtained ? What are its characteristics ? CHAP. XXI Of Chlorine. I. The term chlorine, which signifies a yellowish green colour, is applied to a substance, which was for- merly called oxymuriatic acid gas; it is obtained by mix- ing muriatic acid with oxide of manganese. 2. The merit of this discovery is justly due to Sir H. Davy, who, after submitting the gas to a variety of ex- periments, pronounced it to be an elementary sub- stance. 3. Sir H. Davy submitted to the action of muriatic acid gas, potassium ; by which, more than One third of its volume of hydrogen was produced. He states that muriatic acid can in no instance be procured from oxy- muriatic acid, unless water be present; or from dry mu- riates, unless water or its elements be present. According to the experiments of M. M. Gay Lussac and Thenard, muriatic acid gas contains one quarter of 18 20G IN I110DUCTI0N its weight of water, and oxymuriatic acid is not de- composable by any substance but hydrogen, or such as can form triple combinations with it. 4. One of the most singular facts is, that charcoal, even when ignited to whiteness in oxymuriatic or muri- atic acid gases, by the voltaic battery, effects no change in them, if it has been previously freed from hydrogen and moisture, by intense ignition in vacuo. Observation. The above experiment lead Sir H. Da- vy to doubt the existence of oxygen in oxymuriatic gas, which has been supposed to contain it above all others, in a loose and active state. He then proceeded to a very rigorous investigation of nature, which terminated in an entire conviction that oxymuriatic acid gas was a simple substance, which he placed in the same rank with oxy- gen, and removed it from the class of acids. This opin- ion is now pretty generally embraced by all the most celebrated chemists, although most of the phenomena attending the action of this substance, may be accounted for on the supposition that chlorine be a compound body. Exp. 1. If oxymuriatic acid gas be introduced into a receiver exhausted of air, containing a little tin, and the metal be gently heated, the tin and the gas disappear, and a limpid fluid, called the liquor of Libavius, is form- ed. If this substance be a combination of muriatic acid and oxide of tin, the oxide wdl be separated from it, by means of ummoniacal gas. Exp. 2. Admit ammoniacal gas over mercury to a small quantity of the liquor of Libavius, it will be ab- sorbed, and much heat will he extricated, and no gas generated ; a solid result is obtained, which is of a dull white colour, when heated, the whole is volatilized, pro- ducing dense pungent fumes. TO CHEMISTRY. 207 5. When oxymuriatic acid and ammonia are made to act upon each other, water is not formed. This un- doubtedly would be the result, if the oxymuriatic acid was a compound body, as the two substances would con- tain the elements of that fluid. 6. When chlorine is acted upon by nearly an equal volume of hydrogen, a combination takes place between them and muriatic acid g is is the result. 7. When oxymuriatic acid gas is acted on by mercu- ry, or any other metal, oxymuriatic acid, or chlorine is attracted from the hydrogen by the stronger affinity of the metal, and an oxymuriate is produced. 6. As oxymuriatic acid is not known to contain oxy gen, its name appears absurd, and ought to be erased from the chemical nomenclature, and that of chlorine or some other appropriate term substituted. 9. Chlorine combines with inflammable bodies to form simple binary compounds; and in those cases, when it acts upon oxides, it either expels their oxygen, or causes it to act upon new combinations. 10. The oxygen does not arise from the decomposi- tion of the oxymuriatic acid, but from the oxide, as is evident from its being exactly equal to the quantity con- tained in the oxide used. 11. It appears pretty evident that there is no acid property in oxymuriatic acid, combined with oxygen, be- cause if it were so, it ought to be exhibited in the fluid compound of one proportion of phosphorus, and two of oxymuriatic gas ; on the old hypothesis, it would consist of muriatic acid, and phosphorous acid ; but this substance has no effect on litmus paper, and does not act under common circumstances, as fixed alkaline bases, such as dry lime, or magnesia, 208 INTRODUCTION 12. Oxymuriatic acid, like oxygen, must be combin- ed in large quantities, with peculiar inflammable matter, to form acid matter. Illustration. In its union with hydrogen, it instantly reddens the driest litmus paper, though a gaseous body; contrary to acids, it expels oxygen from protoxides and combines with peroxides. 13. When potassium is burnt in chlorine, a dry com- pound is obtained. 14. The bleaching properties of chlorine was ac- counted for on the old theory, by supposing that it de- stroyed colours by parting with its oxygen, but by the new, the oxygen is derived from the water, with which it must always be combined, in order to produce the ef- fect, by a double affinity, that of hydrogen for chlorine, and of the colouring matter for oxygen. 15. Chlorine is not capable of being condensed at a low temperature, nor crystallized. 16. The solution of chlorine in water, freezes more readily than pure water ; but the pure gas dried with muriate of lime experiences no change whatever, at a temperature of — 40° F. 17. Chlorine is of a greenish yellow colour. Its odour and taste are disagreeable, which is one of its dis- tinguishing characteristics, as it is impossible to mistake tt for any other gas. When breathed, even when much diluted with air, it occasions a sense of strangulation, constriction of the thorax, and a copious discharge from the nostrils. If respired in larger quantities, it excites violent coughing and spitting of blood, and if continued, would speedily destroy the individual, in violent distress. Its specific gravity is 2.4733. In its perfectly dry state, it lias no effect on dry vegetable^ colours; with the aid TO CHEMISTRY. 209 of a little moisture, it bleaches them into a yellowish white'1 Exp. 1. If a lighted wax taper be immersed in this gas, it consumes very fast, with a dull reddish flame and much smoke. Note.—The taper will not burn at the surface of the gas. Exp. 2. Immerse a small quantity of sulphuret of antimony, powdered into a jar containing chlorine, it will immediately take fire and burn spontaneously, the result will be chloride of antimony. The same effect will take place with copper, tin, arsenic and zinc, in powder. Exp. 3. If phosphorus be immersed, as above, it will take fire at ordinary temperatures, and chloride of phosphorus will be formed. 18. Chlorine combines with alkalies, and forms salts, possessed of various properties ; that with potash is most generally known. It was formerly called hyper-oxymuriate of potash, now chlorate. Exp. 1. Put two grains of chlorate of potash in pow- der into a mortar, and add one grain of sulphur. Mix them very accurately by gentle triture, and then having collected the mixture to one part-of the mortar, press the pestle upon it suddenly and forcibly, a loud detona- tion will ensue. Exp. 2. If the mixed ingredients be wrapped in some strong paper, and then struck with a hammer, a still . louder report will be produced. Exp. 3. If five grains of this salt be mixed with half the quantity of powdered charcoal, in a similar manner, and the mixture be strongly triturated, it will inflame,, but with little noise. 18* 210 INTRODUCTION Exp. 4. Mix a small quantity of sugar with half its weight of the salt, dip a glass rod into sulphuric acid, and let a drop fall on the mixture, an instantaneous in- flammation will take place. Exp. 5 Lay two trains, one of gunpowder, and the other of chlorate of potash, in such a manner, as that they may touch at one end, and diverge at the other, in the form of an acute angle ; then apply an ignited coal at the point of contact; both will be inflamed at the same time, but the gunpowder will burn comparatively slow. 19. Chlorine is capable of combining with two pro- portions of oxygen, which are very interesting in their properties, called the protoxide and deutoxide of chlorine, or chlorous and chloric oxides. Exp. Put chlorate of potash into a small retort, and pour in twice as much muriatic acid as will cover it, di- luted with an equal volume of water, by the application of a gentle heat, the gas is evolved ; it must be collected over mercury. 20. Its tint is much more lively, and more yellow than chlorine ; from this circumstance, Sir H. Davy cal led it Euchlorine. Its smell is peculiar, and approaches to that of burnt sugar. It is not respirable. It is soluble in water, to which it gives a lemon colour. Water ab. sorbs 8 or 10 times its volume of this gas. Its specific gravity is to that of common air, nearly as 2.40 to 1. 21. This gas must be collected and examined with great care, and in very small quantities. A gentle heat* fven that of the hand, will cause its explosion, with such force as to burst thin glass. In the act of explosion, the elements arc separated with great violence and some light. 22. The metals which act upon chlorine, will not act upon this at common temperatures ; but when the oxy- gen is separated, they inflame in the chlorine. ro CHEMISTRY. 211 Exp. Let a little gold leaf be introduced into a bottle filled with the protoxide of chlorine, it will undergo no change; but if a heated glass tube be applied to the gas, in the neck of the bottle, a decomposition takes place, and the oxygen and chlorine will be detached from each other, and at the same moment, the leaf will inflame and burn with great brilliancy. 23. The deutoxide of chlorine or chloric oxide is formed by mixing fifty or sixty grains of chlorate of pot- ash with a small quantity of sulphuric acid in a wine glass, very little effervescence takes place, but the acid gradually acquires an orange colour, and a dense yellow vapour, of an agreeable smell, floats on the surface. If this be put into a retort, and heated, by means of hot wa- ter, a gas is obtained, which may be received over mer- cury. 24. Water absorbs more of it than of the protoxide. Its taste is astringent. It destroys vegetable blues with-- out reddening them. When phosphorus is introduced into it, an explosion takes place. When heat is applied, the gas explodes with more violence, and produces more light than the protoxide. When thus exploded, two measures of it are converted into nearly three measures, which consist of a mixture of one measure chlorine, and two measures oxygen. Hence it is composed of 1 atom chlorine, and 4 atoms oxygen. 25. When chlorine is passed through a solution ef ni- trate of ammonia, the gas is rapidly absorbed, and a film appears on the surface, which soon collects into yellow- ish drops, that sink to the bottom of the liquor. 26. This is the most powerful detonating compound known. When gently warmed, it explodes with such violence, as to be attended with very great danger. " It explodes in certain circumstances, with or without heat, 21J INTHODUCTIoN Exp. If a globule of the fluid be thrown into oliva oil, turpentine, or naphtha, it explodes without heat, and so violently as to shatter the glass vessel in which it takes place. PRACTICAL QUESTIONS. To what is the term chloiine applied ? To whom is the merit of the discovery due ? What method did Sir H. Davy take to prove that this was an elementary substance ? What effect does charcoal produce on chlorine ? What did Sir H. Davy infer from these ? What other experiments can you adduce, illustrative of the hypothesis ? Is water formed by the action of oxymuriatic acid and ammonia ? What is formed by the action of chlorine and hydro- gen ? What is the effect of theaction of mercury on oxymu- riatic acid? What phenomenon is produced,when oxymuriatic acid acts on inflammable bodies ? Whence does the oxygen arise in this case ? How does it appear that there is no acid property combined with oxygen in oxymuriatic acid gas ? What is necessary in order that oxymuriatic acid gas may form acid matter ? In its union with hydrogen, what is its effect ? What is obtained from the combustion of potassium in chlorine ? How do you account for the bleaching properties of chlorine ? Can chlorine be condensed ? What are the characteristics of chlorine ? TO CHEMISTRY. 213 What is the combination of chlorine with alkalies ? Illustrate the properties of chlorate of potash by ex- periments ? What arc the combinations of chlorine with oyxgen ? What are the properties of protoxide of chlorine ? Does this substance easily explode ? Will metals act upon this gas ? How is the deutoxide of chlorine formed ? What are its properties ? Does chlorine unite with nitrogen? What are the characteristics of the compound ?. CHAP. XXII. Of Iodine. . I. Iodine is a name given to an elementary substance. It was accidentally discovered by M. De Courtois, a man- ufacturer of salt-petre, at Paris, in 1812. In his process of procuring soda from the ashes of sea weed, he found the metallic vessels much corroded; and in examining into the cause he made this important discovery. It de- rived its first illustration from M. M. Clement, and De- sormes, who named it iodine from the Greek word signi- fying like a violet, from the violet coloured vapour which it formed. 2. Iodine has been found in the following sea weeds, Fucus cartilagineus ; F. membranaceus ; F. filamentosus ; F. rubens ; F. nodosus; F. serratus; F. siliquosus ; F. palmatus ; F. filum ; F. digitatus ; F. saccharimus ; Ulva umbilicalis ; U. pavonia ; U. linza ; and in sponge* 3. It is from the ashes of sea weed, or kelp, that Io- 214 INTRODUCTION dine, in quantities, is to be obtained The following method of extracting it, is given by Dr. Wollaston. Dis' solve the soluble part of kelp in water. Concentrate the liquid by evaporation, and separate all the crystals that can be obtained. Pour the remaining liquid into a clean vessel and mix with it an excess of sulphuric acid. Boil this liquid for some time. Sulphur is precipitated, and muriatic acid driven off. Decant the clear liquid and strain it through wool. Put it into a small flask, and mix with it as much black oxide of manganese, as sulphuric acid. Apply at the top a glass tube shut at one end. Then heat the mixture in the flask. The iodine sublimes into the glass tube. 4. Iodine, when properly prepared, is a solid of a greyish black colour and metallic lustre. It is often in the form of scales, sometimes in rhomboidal plates very large and very brilliant. Its fracture is lamellated, and it is soft and friable to the touch. Its taste is very acrid, though it be very sparingly soluble in water. It is a dead ly poison. It gives a deep brown stain to the skin, which soon vanishes by evaporation. In odour and power of destroying vegetable colours, it resembles very dilute aqueous chlorine. Its specific gravity at 62 1-2° is 4.948. It dissolves in 7000 parts of water. The solution is of an orange yellow colour, and in small quantities tinges starch of a purple hue, which is the most delicate test. When this substance is put into a liquid containing the iodine, in a state of liberty, it detects the presence of so small a quantity as the jj^ijjth by the blue colour which it forms. It evaporates quickly at ordinary temperatures. Boil- ing water aids its sublimation. The specific gravity of its violet vapour, is 8-678. It is a non-conductor of elec- tricity, TO CHEMISTRY. 215 5. Iodine is incombustible, but with azote it forms a curious detonating compound ; and in combining with sev- eral bodies the intensity of mutual action is such as to pro- duce the phenomena of combustion. 6. When iodine and oxides act upon each other in contact with water ; the water is decomposed, its hydro- gen unites with iodine to form hydriodic acid, while its oxygen produces with iodine, iodic acid. All the oxides however, do not produce the same results; only such as potash, soda, barytes, strontian, lime and magnesia. The oxide of zinc, precipitated by ammonia, from its solution in sulphuric acid, and when well washed, gives no trace of iodate or hydriodate. 7. Iodine dissolves in carburet of sulphur, producing in very minute quantities, a fine amethystine tint to the liquid. 8. If iodine and hydrogen be heated in dry hydrogen gas, an expansion of its volume takes place, an acid gas is formed which is very absorbable by water ; and acts so powerfully on mercury that it cannot be preserved for any length of time over that metal. 9. Iodine combines with the metals and forms substan- ces called iodides. PRACTICAL QUESTIONS. What is iodine ? In what is iodine found ? How is it procured ? What are its properties ? Is iodine incombustible ? What is the phenomena of the action-of iodine and ox- ides? What effect has carburet of sulphur on iodine ? 216 INTRODUCTION What is the effect of heating iodine and sulphur to gether ? What are iodides? CHAP. XXIII. Of Salts in general. 1. The term salt is usually employed to denote a compound in definite proportions, of acid matter, with an alkali, earth or metallic oxide. 2. When the proportion of the constituents are so ad- justed that the resulting substance does not change the colour of litmus or red cabbage it is called a neutral salt. 3. When the predominance of the acid is evinced by the reddening of those infusions, the salt Is said to be acidulous, and the term super or bi is prefixed to indicate the excess of acid. 4. If the acid matter appears to be short of the quan- tity necessary for neutralizing the base, the salt is then said to be with excess of base, and the term sub is pre- fixed to the name. 5. There are many substances known by the name of salts to which the above observations will not strictly ap- ply, as the muriates, prussiates, and fluates, for they con- tain neither acids nor alkaline bases. 6. Only those acids which are compounds of oxygen and inflammable bases appear to enter into combination with the alkalies and alkaline earths, without alteration, and it is impossible to define the nature of the arrange- ment of the elements in their neutral compounds. TO CHEMISTRY. 217 Observation. The phosphate and carbonate of lime have much less of the characters attributed to neutral sa- line bodies, than chloride of calcium, muriate of lime, and yet this last body is not known to contain either alkaline or acid matter. 7. The mcst important characteristic in salts is their solubility in water. In this they are usually crystallized, and by its agency they are purified attl separated from one another. 8. We may obtain a perfectly saturated solution of salts in the two following ways. 1. By heating the water with the salt and allowing it to cool to the temperature whose solubility is wanted. 2. By putting into cold water, a great excess of salt, and gradually elevating the tempe- rature. In each case it is requisite to keep the tempe- rature constant for at least two hours, and to stir the sa- line solution frequently, in order to make sure of its per- fect saturation. 9. Saturation in a saline solution of an invariable tem- perature, is a point at which the solvent, always in con- tact with the salt, can neither take up any more, nor let go any more. 10. Every saline solution which Can part with salt without any change of temperature is supersaturated. 11. In general supersaturation is not a fixed point. The cause which produces it, is the same which keeps water liquid below the temperature at which it congeals. That is, absolute rest, or the want of sufficient agita- tion. 12. A salt that contains no water is said to be anhydrous. 13. Salts that consist of an acid and two bases are called triple salts, and take the name of both biises. 14. ^When the bases of a metallic salt contains an ex* 19 *18 INTRODtClloN cess of oxygen, it is distinguished by the abbreviation oxy, as oxy sulphate of iron. 15. When salts are composed of acids ending in ous, they take a termination in ite instead of ate. Illustration. Lime combined with phosphorous acid., is called phosphite of lime, but when combined with the stronger, or phosphoric acid, it is called phosphate of lime. 16. The general characteristics of the muriates are-— When heated, they melt and are volatilized. They are soluble in water. They effervesce with sulphuric acid, and white acrid fumes are disengaged. When mixed with nitric acid, they exhale the odour of chlorine. 17. The general characteristics of sulphates are. They have a bitter taste. They are soluble in water but not in alcohol. Alcohol precipitates them from wat- er in a crystallized form. When heated to redness with charcoal, they are converted into sulphurets. Exp. Put a tea spoonful of sulphate of magnesia into some water, after it is dissolved, and the solution quite clear, add some alcohol to it, and the salt will be precip- itated. 18, The carbonates are soluble in water. When sul- phuric acid is poured upon them, they effervesce violent- ly, emitting carbonic acid gas. • 19. The nitrates are characterized by (heir being soluble in water, ant capable of crystallizing by cooling. When heated to redness with combustible bodies, a vio- lent detonation is produced. Sulphuric acid disengages red fumes from them. When heated with muriatic acid, chlorine is exhaled. 20. The general characters of metallic salts are,— When they are strongly heated, they are volatilized and TO CHEMISTRY". K19 dissipated. Hydro sulphuret of potash occasions a L-lr.ck precipitate from the solution. Muriatic acid when pour- ed into a solution of them in water, usually occasions a white precipitate. Gallic acid occasions a yellow pre- cipitate. A plate of copper plunged into a solution o/ mercurial salts, gradually precipitates running mer- cury. 21. When a warm solution of salt deposits on cool- ing, regular shaped masses, it is said to crystallize. These all difler in different salts, so that by knowing the form of the crystal, the class to which it belongs may be as- certained. Exp. Take half an ounce of Glauber's salt in crystals, dissolve it in the same quantity of hot water; on cooling, crystals of the same shape will be formed. PRACTICAL QUESTIONS. What is the term salt usually employed to denote ? What is a neutral salt ? How do you express the excess of an acid in a salt ? How do you express the excess of base ? Do these observations apply to all substances known by the name of salts ? What acids appear to enter into the composition ©F al- kalies and alkaline bases to form salts? What is the most important characteristic of salts ? What methods are used to obtain a complete saturated solution of salts ? What do you understand by saturation ? What is meant by super saturation ? Is supersaturation a fixed point? When is a salt said to be anhydrous ? What are triple salts ? 220 INTRODUCTION How is a metallic salt distinguished when its ba^u contains an excess of oxygen ? How are salts distinguished whose acids end in mts ? What are the general characteristics of the muri- ates ? What are the characters of the sulphates ? What are the general characters of the carbonates 'I How are the nitrates characterized ? What arc the general character* of metallic salts'.' What is crystallization. CHAP. XXIV. Of Electricity.—Voltaic Electricity. 1. Electricity is supposed to be a fluid which pervades almost all substances, and when undisturbed remains in a state of equilibrium. Observation. The phenomena produced by rubbing a piece of amber, constitutes the first physical fact record'. ed in the history of the science. 2. The certain portion which every body is supposed to contain is called its natural share, and so long as it con- tains neither more nor less than this quantity, it seems to produce no effect. 3. When a body is by any means possessed of more or less than its natural share, it is said to be electrified or charged. 4. If it possess more than its natural quantity it is, said to be positively electrified ; if it contain less, »ega« tieely electrified. TO CHEMISTRY. 221 o. Bodies through which the electric fluid passes freely, are called conducters, or non-electrics. Those bodies which oppose the passage are called non-conduc- tors, or electrics. 6. Two bodies, both positively, or both negatively electrified, repel each other, but if one body be positive and the other negative, they will attract each other. Exp. Take a small phial and rub it hard with a silk handkerchief, it will attract dust and other light substan- ces, when placed hear them. 7. When two bodies approach each other sufficiently near, one of which is electrified positively and the other negatively, the superabundant electricity rushes violently from one to the other, torestore the equilibrium between them. This effect takes place if the two bodies are con- nected by a conducting substance. 8. The motion of electricity in passing from-one body to another, is so rapid that it appears to be instanta- neous. 9. Electricity is produced by the mutual friction of all solid bodies, and of many fluids against solids, provided one of the bodies be of such a nature as to obstruct the speedy diffusion of the electric influence. 10. The following is a list of conducting substances, arranged in the order of their conducting powers. 1 Copper 10 Plumbago 2 Silver 11 Strong acids 3 Gold 12 Soot and Lampblack 4 Iron , 13 Metallic ores 5 Tin 14 Metallic oxides 6: Lead 15 Dilute acids 7 Zinc 16 Saline solutions 8 Platinum 17 Animal fluids 0 Charcoal 18 Sea water 19* 222 INTRODUCTION 19 Water 25 Vapour 20 Ice & snow above 08 26 Salts 21 Living vegetables 27 Rarefied air 22 Living animals 28 Dry earths 23 Flame 29 Massive minerals, 24 Smoke metallic. 11. The following is a list of non-conductors, in the order of their insulating power. 1 Shel lac 14 Baked wood and dryefi 2 Amber vegetables 3 Resins 15 Porcelain 4 Sulphur 16 Marble 5 Wax 17 Massive minerals, not 6 Asphaltum metallic 7 Glass and all vitrified 18 Camphor bodies, comprehending 19 Caoutchouc diamond and crystalliz- 20 Lycopodium ed transparent minerals. 21 Dry chalk and lime 8 Raw silk 22 Phosphorus 3 Bleached silk 23 Ice below 0° F. 10 Dyed silk 24 Oils, of which the dens- 11 Wool, hair and feathers er are best 12 Dry gases 25 Dry metallic oxides, in- 13 Dry paper, parchment eluding fixed alkalies and leather and earthy hydrates. 12. Electricity is excited in the fusion of inflammable bodies. Exp. If melted sulphur be poured into an insulated metallic cup, after it has become solid, the sulphur and cup will be both electrified; the former positive, the h\tter negative. 13. Electricity is prcduced by evaporation. TO CHEMISTRY. 223 Exp. If we place a metallic cup on an electrometer, containing a small quantity of water, and plunge into it a red hot iron, the instrument will indicate electrical phenomena. 14. Electricity is produced by the disengagement of gas. Exp. If into a platinum cup resting on the top of an electrometer, we put a little dilute sulphuric acid, and then throw in some iron filings, or chalk, when the effer- vescence increases, the instrument will indicate electri- cal phenomena. 15. Electricity is produced by the tearing asunder of solid bodies, probably owing to the friction among the particles. Exp. If we suddenly tear asunder pieces of mica, break across a stick of sealing wax, split up a piece of dry and warm wood, or scrape it with a piece of glass, the electrical equilibrium will be disturbed. 16. Electricity is produced by contact of dissimilar bodies. Exp. If we take two flat plates, one of silver or cop- per, the other of zinc, each two or three inches in diam- eter, furnished with glass handles, and bring them into contact by their flat surfaces, we shall find on separating them, that they are both electrified. If we touch a cake of sulphur, gently heated, with the insulated copper plate, the effect will be more striking. Acid crystals, touched with metallic plates, indicate electrical phenom- ena. When crystals of oxalic acid are brought into contact with dry quicklime, electricity is developed. 17. On the excitation of electricity by contact of dis- similar chemical bodies, is founded the principle of gal- vanic action, and the construction of the voltaic battery. 221 .T.S.OD0CT10N 18. Galvanism, or Voltaism, is occasioned, as appear?, by the chemical action of bodies on each other. 19. Galvanism, so named from the person who first promulgated it, appears to have been discovered by ac- cident. Galvani, a professcr of natural philosophy, at Bologna, being engaged in some experiments on muscu- lar irritability, observed, that when a piece of metal was laid on a nerve of a frog, recently dead, whilst the limb, supplied by that nerve, rested on another piece of metal, the limb suddenly moved, on a communication being made between the two pieces of metal. 20. This communication may be made, either by bringing the two metals into contact, or by connecting them by means of a metallic conductor. Exp. Take a piece of zinc, and place it under the tongue, and a piece of silver on the tongne, letting the metals project a little ; then make the projecting part of the metals touch each other, and a singular sensation will be produced. The effect is probably the same as that produced on the frog. 21. Galvani supposed that the virtue of this new agent resided in the frog, but Volta, who paid particular attention to the subject, shewed that the phenomena did not depend upon those organs, but upon the electrical agency of the metals, which is excited by the moisture of the animal. Consequently, the saliva of the mouth answers the same purpose, and produces the sensation in the above experiment. 22. It is not necessary that the fluids used in these experiments should be of an animal nature. Acids, very much diluted with water, are found to be the most effec- tual in the developement of electricity in metals ; and accordingly, the original apparatus, which Volta first constructed for this purpose, consisted of a pile, or sue- TO CHEMISTRY. 225 cession of plates of zinc and copper, each pair of which was connected by pieces of cloth or paper, moistened with water. This, however, was found inconvenient, as well as of little power, which gave rise to the construc- tion of the present Voltaic battery. (Plate 3, fig. 3.) In this, the plates of zinc and copper are soldered together in pairs, each pair being placed at regular distances in wooden troughs, and the interstices filled with fluid. 23. The action of the fluid on metals, whether water or acid be used, is entirely of a chemical nature. But whether electricity be excised by this chemical action, or, whether it be produced by the contact of the two metals, is a point upon which philosophers do not per- fectly agree. 24. Volta and Sir H. Davy explain the action of the voltaic battery on the principle of the contact of the two metals ; but many philosophers entertain doubts on the truth of the theory. The principal difficulty is, that two such plates shew no signs of different states of electricity whilst together,but only on being separated, after contact. Now in the voltaic battery, those plates that are in con- tact, always continue so, being soldered together ; they cannot, therefore, receive a succession of charges. Be- sides, if we consider the mere disturbance of the balance of electricity, by the contact of the plates, as the sole cause of the production of voltaic electricity, it remains to be explained, how this disturbed balance becomes an inexhaustible source of electrical energy, capable of pouring forth a constant and copious supply of electrical fluid, though without any means of replenishing itself from other sources. The theory least liable to objection, appears to be that, first proposed by Dr. Bostock, called the chemical theory. 226 INTRODUCTION This theory supposes the electricity to be excited by the chemical action of the acid upon the zinc. All met- als having a strong attraction for oxygen, and this ele- ment being found both in the water and the acid. The action of the diluted acid on the zin<\ consists in its oxy- gen, combining with the metal, and oxidating its sur- face. 25. It appears that all metals are united with the positive electricity, and that oxygen is the source of the negative. 26. In the galvanic action, the oxygen does not ap- pear to act on the copper, because the zinc has a strong- er affinity for oxygen than the copper ; the energy of the acid is, therefore, only exerted upon the zinc. 87. If a plate of zinc be placed opposite to one of copper, or any other metal less attractive of oxygen, and the space between them, suppose of half an inch in thick- ness, be filled with an acid, or any fluid capable of oxi- dating the zinc, the oxidated surface will have its ca- pacity for electricity diminished, so that a quantity of electricity will be evolved from the surface. This will be received by the fluid in contact; by which it will be transmitted to the opposite metallic surface, the copper, which is not oxidated, and is therefore disposed to re- ceive it, so that the copper plate will become positive, while the zinc plate will be in the negative state. Observation. This evolution of electricity will be very limited, for as these two plates admit of but very little accumulation of electricity, and are supposed to have none with other bodies ; the action of the acid, and farther developement of electricity will be immediately stopped. 28. In order that the acid may act freely on the zinc, • pnd the two electricities given out without interruption, 10 CHEMISTRY. 227 some method must be devi-ed by which the plates may part with their electricities as they receive them. If the wires connected with either plate are made to meet, the two electricities will then be brought together, and will combine and neutralize er.ch other, as long as this communication continues ; the two plates will dispose of their respective electricities, and the action of the acid will be continued. 29. The intensity of the electricity is increased by increasing the number of plates. If we take four plates, two of zinc, and two of copper, placed alternately in a trough, filled with diluted nitrous acid, and the two cen- tral ones be soldered together, as in the voltaic battery, so as to form but one plate, two dissimilar surfaces will be afforded, the one of copper, the other of zinc. Now a quantity of electricity being evolved from the first zinc plate, in consequence of the action of the acid, is conveyed by the interposed fluid to the copper plate, which thus becomes positive. This copper plate com- municates its electricity to the zinc plate, to which it is joined, in which some communication of electricity takes place. When, therefore, the fluid in the next cell acts upon the zinc plate, electricity is extricated from it, in larger quantity, and in a more concentrated form than before. This concentrated electricity is again conveyed by the fluid to the next pair of plates, when it is further increased by the action of the fluid in the third cell, and so on to any number of plates of which the battery may consist ; so that the electrical energy will continue to accumulate, in proportion to the number of double plates; the first zinc plate of the series being the most negative, and the last copper one, the most positive. 30. If the battery remain undisturbed, the action will soon stop, unless some vent be given to the accumulated 228 INTRODUCTION electricities. This is easily done, however, by estab- lishing a communication by means of the wires (plate 3, fig. 3,) between the two ends of the battery ; these be- ing brought into contact, the two electricities meet, and neutralize each other, producing the shock and other phenomena of electricity ; And the action goes on with renewed energy, being no longer obstructed by the ac> cumulation of the two electricities. ■31. The great superiority of the voltaic battery con- sists in the large quantity of electricity which passes; but in regard to the rapidity or intensity of the charge, the common electrical machine greatly surpasses it. It appears that the shock or sensation depends chiefly upon the intensity; whilst on the contrary, for chemical pur- poses, it is quantity which is required. In the voltaic battery, the electricity though copious, is so weak as not to be able to force its way through the fluid which sepa- rates the plates ; whilst that of a common machine will pass through any space "of water. 32. The action of the voltaic battery may actually be increased, until it equals a weak electrical machine, so as to produce a visible spark when accumulated in a Leyden jar. But it can never be raised sufficiently to pass through any considerable extent of air, because of the ready communication through the fluids employed. 33. The intensity is increased by increasing the num- ber of plates of a battery, whilst by enlarging the dimen- sions of the plates, the quantity is increased ; and as the superiority of the battery over the common electrical machine, consists entirely in the quantity of electricity produced, it was at first supposed that it was the size, rather than the number of plates, that was essential to the augmentation of power. It was, however, found by experiment, that the quantity of electricity produced by TO CHEMISTRY. 229 the voltaic battery, even when at the rate of a very moderate size, was sufficiency copious, and that the chief advantage in this apparatus was obtained by increasing the intensity, which, however, still falls short of that of the common machine. 34. A battery may be formed to shew the galvanic effect on a small scale, in the following manner. It con- sists of a row of cups or tumblers, containing salt and water, or nitrous acid and water. Into each of these, is plunged a plate of zinc, and another of copper. These plates are made to communicate with each other by -means of a thin platina wire, fastened so that the copper of the first glass is connected with the zinc of the sec- ond, the copper of the second with the zinc of the third, and so on through the whole row of glasses ; when one hand is dipped into the first glass, and another in the last, the shock is perceived. But this battery is not con- venient, on account of the great space which it must necessarily occupy. 35. The battery of the royal institution, (London) constructed by Mr. Children, is the most powerful in the world, in calorific effect. It consists of 2000 pairs of • plates, of 32 inches each, exposing a surface of 128,000 square inches. This battery, when the cells were filled with 60 parts of water, mixed with one part of nitric acid, and one of sulphuric acid, afforded a series of bril^ liant and impressive effects. Exp. 1. When pieces of charcoal, about an inch long, and one sixth of an inch in diameter, were brought with- in l-80th or l-40th of an inch of each other, a bright spark was produced, andmore than half the volume of charcoal was ignited to whiteness, and by drawing back the points a little from each other, a constant discharge took place, through the heated air, in a space equal at 20 230 INTRODUCTION least to four inches, producing a most brilliant m-cending arch of light, expanded and conical in the middle. When any substance was introduced into this arch, it instantly became ignited. Exp. 2. Platinum melted in it, like wax in the flame of a common candle. Likewise quartz, sapphire, mag- nesia and lime. Fragments of diamond, and points of charcoal and plumbago, rapidly disappeared, and seemed to evaporate in it, even when the connection was made in an exhausted receiver, but there was no evidence of their previously having undergone fusion. 36. When the communication between the points, positively and negatively electrified, was made in air rarefied in the receiver of an air pump, the distance at which the discharge took place increased as the exhaus- tion proceeded, and when the atmosphere in the vessel supported only an inch of mercury in the barometrical gauge, the spark passed through a space of nearly half an inch. By making the points recede from each other, the discharge was made through 6 or 7 inches, produc- ing a most beautiful coruscation of purple light ; the charcoal became intensely ignited, and some platinum wire attached to it, fused with beautiful scintillations, and fell in large globules on the plate of the pump. All the phenomena of chemical decomposition were produc- ed with intense rapidity, by this combination. Exp. When the points of charcoal were brought near each other in non-conducting fluids, such as oils, ethers, and chloriodic compounds, brilliant sparks occurred, and elastic matter was generated. 37. There are no fluids known except such as con- tain water, which are capable of being made the medium of connexion between the metals, or metal of the voltaic apparatus ; and it is probable that the power of water TO CHEMISTRY. 231 to receive double polarities, and to evolve oxygen and hydrogen is necessary to the constant operation of the connected apparatus. 38. It is probable that acids, or saline substances, in- crease the action of the battery, by affording elements which possess opposite electricities to each other when mutually excited. 39. The following simple experiment shews the man- ner in which aqueous fluids propagate electrical polarity among their particles. Cut narrow filaments of tin foil into lengths of almost half an inch, and place them in a line on the surface of an oblong trough of water. On plunging into the water at each end, wires connected with the two extremities of an active voltaic battery, the metallic filaments will immediately acquire polarity. Their positive and negative poles will become regular- ly opposed to each other, the first depositing oxide, and the last evolving hydrogen. The analogy with magnetic actions is here very complete. 40. That the decomposition of the chemical agents is connected with the energies of the pile, is evident from all the experiments that have been made. No sound objection has been urged against the theory, that the contact of the metals destroys the electrical equili- brium, that the chemical changes restore it, and, conse- quently, that the action exists as long as the decomposi- tion continues. 41. Salts, as well as other substances, may be decom- posed by electricity, and their elements thus ascertain- ed. 42. If we dissolve a quantity, however small, of any salt, in a glass of water, and plunge into it the extremi- ties of the wires which proceed from the two ends of the voltaic battery, the salt will be gradually decom- 232 INTRODUCTION posed, the acid being attracted by the positive, and the alkali by the negative wire. If pieces of paper, stained with certain vegetable colours, which are altered by the contact of an acid, or an alkali, be placed in the glasses, the colours will be changed, agreeably to the above phenomena. Illustration Filue vegetable preparation of litmus be- comes red, when touched hy an acid ; and the juice of violets becomes green by the contact of an alkali. 43. The experiment can be made in a much more distinct manner, by receiving the extremities of the wires into two vessels, so that the alkali shall appear in one vessel, and the acid in another. 44 Let the two vessels be connected together by some interposed substance, capable of conducting elec- tricity, as a piece of moistened cotton thread. Plate 4, fig. 2. c. Put into each of the glasses, a little sulphate of soda, which consists of an acid and an alkali, then fill the glasses with water, which will dissolve the salt.— Now connect the glasses by means of the wires, e. d. with the two ends of the battery. Bubbles soon begin to rise from the decomposition of the water. In order to render the separation of the acid from the alkali visi- ble, pour into the glass, a. which is connected with the positive wire, a few drops of a solution of litmus, and into the other glass, b. which is connected with the neg- ative wire, a few drops of the syrup of violets. The lit- mus immediately begins to turn red, and the violet solu- tion, green. Exp. 1. Take three glasses, plate 4, fig. 3, a. b. c. connected together by wetted cotton, but the middle one only contains a saline solution, the two others containing distilled water, coloured as before, by vegetable infu- sion^ ; yet on making the connection with the battery, WvVW«VVWVWV»VVWV»MMM\»\\M»\VV«\**MVW*VkM-VVV»%VV\ll«»tlVVVVVVV»»«V*Vl»*«* NAMES. I 9 ?10 | 12 ? 13 Platinum Gold Silver Palladium Mercury Copper Iron Tin Lead Nickel Cadmium Zinc Bismuth Sp. gr. 14 Antimony Manganese Cobalt 15 16 ? 17 Tellurium j 18 Arsenic 19 20 21 '22 Chromium Molybde'm Tungsten Columbium | 23 Selenium 24 Osmium 25 | 26 \ 27 5 28 $29 $30 Rhodium Iridium Uranium Titanium Cerium Wodanium 31 Potassium J 32 I 33 5 34 J 35 J 36 { 37 $38 \ 39 \ 40 HI f 42 i 43 Sodium Lithium Calcium Barium Strontium Magnesium Yttrium Glucinum Aluminum Thorinum Zirconium Silicium Precipitants. 21.47 19.30 10.45 11.8 13.6 8.9 7.7 7.29 11.35 8.4 8.6 6.9 9.88 6.70 8. 8.6 6.115 I 8.35 ? \ 5.76 ? 5.90 8.6 17.4 5.6? 4.3? 10.65 18.68 9.0 9 ? 11.47 0.865 0.972 Colour of precipitates J>y FerropTuislateT^^ of llsl of potash. Mur. ammon. { Sulph Iron ( Nit.mercurj Common salt Prus. mercury Common salt Heat Iron Succin. soda with perox. Corr. sublim 0 Yel'wish white White Deep orange White passing to yellow Red-brown Blue, or white passing to blue White Sulph soda Sulph. potash ? Zinc Alk.carbonates Water i Water \ Zinc Tartr. Pot. Alk.carbonates { Water ( Antimony Nitr. lead Do. Do? Mur. lime ? Zinc or inf.gals ( Iron I Sulphite am. Mercury Zinc? Do? Ferroprus.pot. Inf. galls Oxal amm. Zinc { Mur plat. ( Tart, acid Do. Do. Do. Do. Do. With dilute so- lutions,white White Brown yellow 0 White Green Brown Dilute acids Olive 0 0 Brown-red Grass-green Milk-white Pearl-grey 0 0 Green; met. Yellow-brown Orange yellow Brown Perox. 0 Perox-black 0 White Grey-white 0 . 0 Yellow While from water 0 Yellow white Yellow Hydrosulphur- ets. Yellow Black Blackishbrown Sulphuretted hydrogen. Bl'k. met.pow. Yellow Black Black-brown Brownish bl'ck Black Brown Deep brown Orange Purple passing to deep blue 0 Chocolate Red brown 0 0 0 Black Black Protox. black Perox. yellow Black " Do. Orange yellow White Black-brown Orange White Black Blackish Yellow Green Chocolate 0 Brown-yellow Grass-green White Do. 0 Brown 5 Black \ ° \ Orange yellow 5 Yel'wishwhite \ Black brown c Orange s Milkiness i 0 | Yellow Brown TO CHEMISTRY. 233 Hie alkali will appear in the negative glass c. and the acid in the positive glass a. though neither of them con- tained any saline matter. The acid and alkali are con- veyed right and left, from the central glass. 45. Voltaic electricity is of extensive use in chemis- try. It has, of late years, brought to light many impor- tant facts, a knowledge of which, would probably never have been obtained, independent of this powerful agent PRACTICAL QUESTIONS. What is electricity ? What is called the natural share of a body ? When is a body said to be electrified or changed ? When is it positively and negatively electrified 1 What are called conductors and non-conductors ? When do bodies repel each other ? What is the effect when two bodies approach each other, the one being positively, and the other negatively electrified ? How great is the motion of electricity ? How is electricity produced ? What are the conducting substances ? What are the non-conducting substances ? Is electricity ever excited by fusion ? Illustrate it. Is electricity produced by evaporation 1 Illustrate it. Does the disengagement of gas produce it ? Illustrate it. Does the tearing asunder of solid bodies produce it,2 Illustrate it. Is electricity produced by contact ? Illustrate it. What principle is founded on this ? 20* 231 INTRODUCTION How is galvanism occasioned ? How was it discovered ? How may the communication be made ? Illustrate by an experiment. Where does the agency reside ? Must the fluids used, be of an animal nature ? Of what nature is the action of the fluid ? What is supposed to be the cause of the action of the voltaic battery ? What is the theory least liable to objection ? What is the source of the positive and negative elec- tricity ? Why does not the oxygen act on the copper in the galvanic battery ? What will be the effect, if a plate of zinc be placed opposite to one of copper, and the space between them filled with any fluid ? What is necessary in order that the two electricities may be given out without interruption ? How do you increase the intensity of electricity ? If the battery remain undisturbed, will the action stop ? In what does the great superiority of the voltaic bat- tery consist?" Can the electricity of the voltaic battery be collected in a Leyden jar ? How may the quantity of electricity be increased ? How can you shew the action of the voltaic battery on a small scale ? Describe the battery of the Royal Institution. Rehearse some experiments. What fluids are capable of being made the medium of communication ? On what principle do acids or saline substances act ? TO CHEMISTRY. 235 How do you shew electrical polarity among aqueous particles ? With what is the decomposition of chemical agents connected 1 How can salts be decomposed by electricity ? Relate the different methods. Is voltaic electricity of any use 1 CHAP. XXV. Of Metals. I. Metals are the most numerous class of undecom- pounded chemical bodies ; and are distinguished by the following properties. 1. They possess a peculiar lustre, which continues in the streak, and in their smallest frag- ments. 2. They are fusible by heat, and in fusion, re* tain their lustre and opacity. 3. Except selenium, they are all excellent conductors of caloric and electricity. 4. Many of them may be extended under the hammer, and are called malleable ; or under the rolling press, and are called laminable ; or drawn into wire, and are called ductile. Observation. This capability of extension, depends in some measure, on a tenacity peculiar to the metals, and which exists in the different species with very different degrees of force. 2. When the saline combinations of the metals are electerized, the metal separates at the negative pole. 3. When exposed to the action of oxygen, chlorine or iodine, at an elevated temperature, they generally 23-3 INTRODl'CTION take fire, and combining with one or other of these three elementary solvents in definite proportions, are con- verted into saline or earthy looking bodies, void of me- tallic lustre and ductility, called oxides, chlorides, or io- dides. 4. They are capable of combining in their melted state, with each other, in almost every proportion, con- stituting the important order of alloys, in which the char- acteristic lustre and tenacity are preserved. 5. From their brilliancy and opacity, they reflect the greater part of the light which falls on their surfaces ; in consequence of this property they form excellent mir- rors for telescopes and other purposes. 6. Most of them combine in definite proportions with sulphur and phosphorus, forming bodies frequently of a semi-metallic aspect, others unite with carbon, hydro gen and borax, giving rise to peculiar gaseous or solid compounds. 7. Many of the metals are capable of assuming, by particular management, crystalline forms, which are, for the most part, either cubes or octahedrons. 8. The metals have been variously classed by differ. ent ehemists ; it is a task of no small difficulty. The following is the arrangement of Dr. Ure, of ^Glasgow. It commences with those metals which possess the obvious qualities of unalterability by common agents; tenacity and lustre. This order indicates very nearly, their relations to oxygen; and as we descend the series, the influence of that element increases. Among the substances near the head, powers of oxygen are subjugated by the metal- lic constitution, but among those near the bottom, it is very predominant, which the pile of Volta can only disengage; but the metal soon re-unites with oxygen. TOCHEMISTRY. 237 9; The first twelve, together with the 31st, 32d, and 33d, are malleable. 10. The first 16 yield oxides which are neutral sal- ifiable bases. 11. The metals, 17, 18, 19, 20, 21, 22 and 23, are acidifiahle by their combining with oxygen. The remain- ing ones from the 31st form with oxygen, the alkaline and earthy bases. The oxides of those from the 23d to the 31st are but little kuown. 12. Metallic alloys may be analyzed in the following manner, which is a beautiful experiment to show the or- der of affinities. Exp. Take an alloy composed of silver, copper, leadr bismuth and tin. Let it be dissolved by the aid of heat in an excess of nitric acid, of the specific gravity 1.23. Evaporate the solution almost to dryness and pour water on the residuum. We shall thus obtain a solution* of silver, copper and lead, while the oxides of bismuth and tin will be precipitated. By exposing this precipi- tate to the action of nitric acid, the oxide of bismuth will be separated from that of tin. To determine the propor tions of the other metals, pour, first, into the hot and pretty diluted solution, muriatic acid, which will throw down the silver. After filtration, add sulphate of soda to separate the lead ; and finally carbonate of potash to pre- cipitate the zinc. The quantity of each metal may now be deduced from the weight of each precipitate, accord- ing to its specific nature. PRACTICAL QUESTIONS. How are metals distinguished ? What is the' consequence of electerizing the saline combinations of the metals ? What is the effect of exposing them to the action of oxy- gen, chlorine and iodine 1 238 INTRODUCTION Are they capable of combining with each other ? Is their brilliancy and opacity of any use? Do they combine with sulphur and phosphorus ? Do they ever assume a crystalline form? How are the metals classed ? Name the metals and their specific gravities I Which of them are malleable ? Which are acidifiable ? Give an example of analysis ? CHAP. XXVI. Of Platinum—Gold—Silver—Palladium—Mercury. 1. Platinum orPlatina, in the Spanish language, .sig- nifies little silver. It is of a greyish colour, almost black when polished, insipid, inodorous, softer than iron, and less ductile than Gold. It is the heaviest of all metals hitherto discovered. 2. It is most difficult of fusion, for this purpose it requires a degree of heat equal to about 175° of Wedgwood, or 11560 Farenheit. It readily conducts electricity.—It is unalterable in the air. 3. Muriate of tin is a delicate test of platinum. Exp. 1. A single drop of the recent solution in muri- atic acid, gives a bright red colour to a solution of muri- ate of platinum scarcely distinguishable from water. Exp. 2. If the muriatic solution of platinum be agita- ted with ether, the ether will become impregnated with the metal. It is of a fine pale yellow, does not stain the skin, and may be precipitated by ammonia. Exp. 3- If the muriatic solution of platinum be pre*- TO CHEMISTRY. 239 tipitated by lime,"and the precipitate digested in sulphur- ic acid, a sulphate of platinum will be formed. 4. Platinum does not combine with sulphur directly, but is soluble by the alkaline sulphurets, and precipitable from its nitro muriatic solution by sulphuretted hydro- gen. 5. Platinum may be united with phosphorus by pro- jecting small bits of phosphorus on the metal heated to redness, in a crucible,or by exposing to heat four parts each of concrete phosphoric acid, and one of charcoal powder. 6. The phosphuret of platinum is of a silvery white, very brittle and sufficiently hard to strike fire with steel. It is more fusible than the metal itself, and a strong heat expels the phosphorus. 7. Platinum unites with most other metals. Exp. Added in the proportion of 1 12th to gold,it forms a yellowish white metal, highly ductile, and of considera- ble tenacity, having the spcific gravity of 19.013. 8. Platinum renders silver harder, but its lustre duller. 9. Copper is much improved by alloying with pla- tinum. Exp. If 1-6th or l-25thbe added to copper, it be- comes of a golden yellow colour, much harder, of a finer polish, smoother grained and much less liable to rust. 10. There are two oxides of platinum, the protoxide which may be obtained by pouring a solution of neutral nitrate of mercury into a dilute solution of muriate of platinum. A dark brown, or olive green precipitate is formed, which must be well washed and heated, so as to expel the mercury. The protoxide consists of Platinum, 400.00 Oxygen, 4.423 240 IXTRODUCTIOS 11. The peroxide appears to contain three prime proportions. It is obtained by treating the muriate of platinum with sulphuric acid at a distilling heat, and de- composing the sulphate with aqua potassae. It is a yel- lowish brown powder, easily reducible at a red heat, to the metallic state. 12. It unites with chlorine in two proportions, form- ing the proto chloride and the bichloride. The former is soluble in water, while the latter is insoluble. The bichloride appears to consist of Platinum, 100 or 1 prime 23.73 Chlorine, 27.932. 9.00 13. The salts of platinum have the following general characters. 1. Their solution in water is yellowish brown. 2. Potash and ammonia determine the formation of small orange coloured crystals. 3. Sulphuretted hy- drogen throws down the metal in a black powder. 4. Ferroprussiate-of potash and infusion of galls occasion no precipitate. 14. Fulminating Platinum is formed in the following manner. Into a solution of the sulphate in water, aque- ous ammonia is poured, and the precipitate which falls being washed,is put into a matrass with potash ley,and boil- ed for some time. It is then filtered, washed and dried. A brown powder is obtained, which is the fulminating pla- tinum. It explodes violently when heated to 400° ; but does not detonate by friction or percussion. It is a non- conducter of electricity. With sulphuric acid it forms a deep coloured solution. Chlorine and muriatic acid gas decompose it. 15. From its hardness, infusibility, and difficulty of being acted upon by most agents, platinum is of great use in the fabrication of many chemical utensils. TO CHEMISTRY. 241 16. Gold is a yellow metal, very soft, ductile, tough and malleable, unalterable and fixed in the air, or the strongest heat of a furnace. The electric shock converts it into a purple oxide. It melts at 32°, W. Its colour, when melted, is of a bluish green, and the same colour is exhibited when light is transmitted through gold leaf. Its ductility is so great that it may be beaten into leaves of JT Jj^ part of an inch in thickness. 17. It is soluble in nitro-muriatic acid and aqueous chlorine. 18. Gold may be precipitated from its solution by lime, magnesia and the alkalies. 19. There is a strong affinity between the oxide of Gold and muriatic acid. The theory of its solution is the nitric acid of the nitro-muriatic furnishes oxygen soon as to the gold, and the muriatic acid dissolves that oxide as formed. 20. There are two oxides of gold, the protoxide which is of a purple colour, and the peroxide which is yel- low. These may be decomposed by heat. The protoxide seems to consist of 100«aetal -J- 4 ox- ygen. The peroxide of 100 metal -f 12 oxygen. The prime equivalent of gold appears to come out 25. 21. Gold combines with a great number of metals and forms with them a variety of alloys. It will combine al- so with phophorus, forming with it a phosphuret of gold, which is brittle, whitish, and has a cyrstallized appear- ance. Exp. 1. A leaf of Gold introduced into ajar of chlo. rine will take fire and burn. Exp. 2. Solution of gold gives a purple colour to the 21 242 INTRODUCTION skin. It is used for staining ivory, feathers, porce- lain, &c. Exp. 3. The oxide of gold combined with ammonia makes fulminating gold, which explodes with great vio- lence by means of heat. Exp. 4. Ribands moistened with the dilute solution of gold, and exposed to a current of hydrogen gas, will be gilt. By means of a camel's hair pencil, dipt in the solution and applied to different parts of the ribands, fig- ures in gold may be given to them which will be veiy permanent. Exp. 5. A sheet of tin immersed in a solution of gold, precipitates the gold of a purple colour, which, when col- lected, forms a powder much used in enamelling. Exp. 6. If ether be added to a solution of muriate of gold. the gold will leave the acid and float on the surface, com- bined with ether. 22. Green sulphate of iron is a good test for gold. Exp. To a solution of gold add a solution of sulphate of iron, a precipitate will be formed of a brown colour. 23. Mercury has a strong affinity for gold,with which it unites in all proportions and forms an amalgam, which is softer the larger the proportion of mercury. 24. Gold coins and medals are alloys of gold and cop- per, and in all cases the degree of purity of the gold is expressed by the number of parts of that metal contained in twenty-four parts of any mixture. Illustration. Gold, which in twenty-four parts called carats, contains twenty-two of pure metal, is said to be twenty-two carats fine, and absolutely pure gold is said to be twenty-four carats fine. TO CHEMISTRY. 243 25. Silver is the whitest of all metals. It is harder than gold, very ductile and malleable, but less so than gold, silver leaf is more than one third thicker than gold; in this state it does not transmit light. It ignites before melting, and requires a strong heat to fuse it. It is vitrified by the heat of a very powerful lens. 26. In the electric circuit of a powerful galvanic bat- tery, silver leaf may be made to burn with a beautiful green light. 27. The air has very little effect on it, though it ob- tains a purple or btyck coating in contact with sulphur- eous vapours,which are cmited from animal substances in a state of decomposition. This coating is found to be a sulphuret of silver. 28. There seems to l.fj only one oxide of silver, which is formed by intense ignition in an open vessel, when an olive coloured glass is obtained, or by adding a solution of caustic barytes to one of nitrate of silver, and heating the precipitate to dull redness. It consists of 100 silver and -j-7. 3 oxygen. 29. Silver combines with chlorine, and was formerly called luna cornea, or horn silver. It may be formed by ad- ding a solution of muriate of soda to one of nitrate of silver. 30. Fulminating powder may be formed with silver, which may be very terrible in its effects. It is made by pouring lime water into a solution of the pure nitrate and filtering, washing the precipitate, and then digesting on it liquid ammonia for twelve hours. The ammonia must he cautiously decanted from the black powder, which is to be dried in minute portions, and with great caution, on bits of filtering paper or card. 31. If struck, even in its moist state with a hard body. 214 INTRODUCTION it explodes; and if in any quantity when dry,the fulmtna- tion is tremendous. 32. If the decanted ammonia be gently heated, it effer- verces from disengagement of azote, and small crystals appear in it when it cools. These possess a still more formidable power of detonation, and will scarcely bear touching even under the liquid. It appears to be a com- pound of oxide of silver and azote. 33. The sudden extrication of the condensed gas is the cause of the detonation. 34. Silver is soluble in sulphuric acid at a boiling heat, when concentrated. Nitric acid dissolves more than half its weight of silver. It destroys and corrodes animal substances very powerfully. When crystallized, melted and cast into sticks it forms the Lunar caustic of the shops. 35. Nitrate of silver may be decomposed by other metals; a plate of copper to which it is applied becomes plated ;vitb silyer. Exp. Spread a few drops of nitrate of silver upon a piece of window glass by means of a camel's hair pencil; at the bottom of it in contact with the fluid, place a small brass or copper wire ; let it remain undisturbed; and in a short time, it will begin to shoot into apparent vegeta. tion, 36. For silvering of dial plates, scales of barometers, thermometers, &c. The muriate of silver is chiefly used, from which the silver is precipitated and unites with the coppery surface. 27. A useful solvent of silver is formed by dissolving one part of nitrate of potash, by weight in eight or ten parts of concentrated sulphuric acid. This compound called nitro-sulphuric acid, when heated below the tem- perature of boiling water, dissolves a sixth or even a fifth TO CHEMISTRY, 215 afits weight of silver, with an extrication of nitrous gas, and leaves the copper or other metal with which the sil- ver may be combined. This is of great use in extracting silver from plated articles. 38. The beautiful representation called Diana's tree, may be made in the following manner. Take three drams and a half of pure silver, and half as much mer- cury ; dissolve them separately in sufficient quantities of pure nitric acid, then mix the solution and add to them five or six ounces of distilled water. This is to be pour- ed upon rather less than half an ounce of an amalgam of silver, which is put into a spherical glass vessel. In the course of twenty four hours the silver tree will be form- ed. 39. Silver is found in various parts of the world, in a metallic state, a sulphuret and an oxide. EXPERIMENTS. 1. Add a few drops of muriatic acid to some nitrate of silver, a white curdy or flaky precipitate falls down in: great abundance, this precipitate is decomposed by light, for if exposed to the direct rays of the sun, its colour be- comes darker. 2. If one part of muriate of silver be mixed with three parts of carbonate of soda and fused in a crucible, the sil- ver will be reduced and found at the bottom of the cruci ble. 3. A solution of the nitrate of silver stains animal sub- stances of a deep black: It has been applied to the stain- ing of the human hair. 4. White paper when stained with a solution of nitrate of silver,in the proportion often parts of water and one 246 INTRODUCTION of the s;il(, and exposed to the light, acquire* colour and passes through all the changes to black. 5. Let a slip of ivory be immersed in pure nitrate of silver, trill it acquires a bright yellow colour ; then re- move it into a glass of distilled water, and expose it to the direct light of the sun; it will, after two or three hours, become black, but on rubbing it a little, the sur- face will be changed into a bright metallic one. 40. Palladium is a new metal first found by Dr. Wol- laston, in ores of Platina. It is scarcely distinguished from the crude platina, though much harder. 41. Palladium is of a greyish white colour and takes a good polish. It is ductile and very malleable ; and be- ing reduced into thin strips is flexible, but not very elas- tic. Its fracture is fibrous, and in diverging striae, ex- hibiting a kind of crystalline arrangement. In hardness it is superior to wrought iron. It is a less perfect conduc- tor of caloric than most metals, and less expansible, though in this it exceeds platina. On exposure to a strong heat its surface tarnishes a little and becomes blue, but an increased heat brightens it again. It requires more heat than that of gold for its fusion, but if touched when hot with a small bit of phophorus, it runs like zinc. The sulphuret is whiter than the metal itself, and ex- tremely brittle. 42. It is soluble in nitric acid, which soon acquires a fine red colour, but the quantity dissolved is small. Ni- trous acid acts on it more quickly and powerfully. SuL phuric acid by boiling, acquires a similar colour, dissolv- ing a small portion. Muriatic acid acts much in the same manner. Nitro-muriatic acid acts upon it powerfully, and assumes a deep red. 43. Alkalies and earths throw down a precipitate of a ace orange colour. Recent muriate of tin precipitates TO CHEMISTRY. 247" it of an orange or brown colour, or a beautiful emerald green. Creen sulphate of iron precipitates the palladi- um in a metallic state. Sulphuretted hydrogen, dark brown. All the metals, except gold, silver and platina, precipitate it in a metallic state. 4 1. Mercury has derived several names from its sim- ilarity to silver ; as quicksilver, argentum vivum, and hy- drargyrum. 45. It is distinguished from all other metals, by its extreme fusibility ; it is not solid until cooled down to the 39 — 0 of Farenheit ; of course, it is always fluid in our climate. Its colour is white, and rather bluer than silver. In the solid state, it is malleable. It is volatile, and rises in small portions in the common temperature of the atmosphere. It boils at the temperature of 656°. When exposed to a heat of 600°, it gradually acquires oxygen, and is converted into a red powder, or oxide, which is said to be the tritoxide. This was formerly known by the name of precipitate per se. From its vola tility, it is commonly purified by distillation. 46. There have been reckoned three oxides of mer- cury. 1. The protoxide, when the mercury is con- verted into a black powder by agitation, formerly called ethiops per se. 2. When it is dissolved in nitric acid with- out the assistance of heat, the deutoxide is formed.— 3. When exposed to the heat of 600° for a considerable length of time, the peroxide is formed. 47. Mercury combines with sulphur and phosphorus very readily. Exp. If two parts of sulphur by weight, and one of mercury, be triturated together in a mortar, the mercury gradually disappears and the mass assumes a black col- our. In this state, it was formerly called ethiops mineral^ but it is now found to contain mercury, sulphur, and sul- 248 INTRODUCTION phuretted hydrogen, and on that account, is denominated' hydrosulphuret of mercury. The sulphur imbibing hy- drogen from the moisture of the atmosphere. 48. If hydro-sulphuret of mercury be heated, part of the sulphur is dissipated, and the compound assumes a deep violet colour. 49. Vermillion is composed of mercury and sulphur, united by fusion and sublimed. It is obtained in a fine red cake, and in this state it was called cinnabar ; it is the red sulphuret of mercury. 50. Phosphuret of mercury is formed from phospho- rus and the black oxide of mercury, or protoxide, melted in a retort filled with hydrogen gas. This latter sub- stance prevents the combustion of the phosphorus. This substance being formed of the oxide and not of the pure mercury, has been called black phosphuretted oxide of mercury. 51. The following metals are soluble in mercury, when mixed in sufficient quantities. Gold, lead, bis- muth, osmium, silver, tin, zinc. 52. On the amalgamating property of mercury, the silvering of looking glasses depends. An amalgam is form- ed, by pouring mercury on tin foil, laid perfectly smooth on a marble slab, and the glass slided on it, and kept down by weights. 53. Sulphuric acid will not act upon mercury, when cold ; hence, it has been used to purify mercury from foreign materials, for barometers and thermometers. 54. Muriatic acid does not sensibly act on metallic mercury, except by long digestion, when it oxidates a part, which is immediately dissolved. It readily dissolves the oxides. 55. Nitric acid acts with great energy on mercury, and during the operation, nitrous gas is disengaged.— TO CHEMISTRY. 249 The nitrate contains a greater or less proportion of oxy- gen, as it is prepared with or without heat. 56. All the nitrates of mercury are very caustic, and form a deep purple, or black spot on the skin. They afford crystals, which differ according to the state of the solution. 57. When the crystals of nitrate of mercury are sub- mitted to a long continued heat, they give out a portion of nitric acid, and are converted into a bright red oxide, called red precipitate. 68. Mercury combines with chlorine, and forms two well known compounds, viz. calomel, or the proto chlo ride, and corrosive sublimate, or the perchloride, called by some, the deutochloride. 59. The perchloride of mercury consists of Mercury, 25 73.63 Chlorine, 9 26.67 100.00 The protochloride of Mercury, 25 84.746 Chlorine, 4.5 15.254 100.000 60. Mercury is extensively used in the arts and in medicine. PRACTICAL QUESTIONS. What is platinum and its characteristics ? Is it easily fusible ? What is a test of platinum ? Does platinum combine with sulphur ? Can platinum be united with phosphorus ? • What are the properties of phosphuret of platinum ? Does platinum unite with any of the metals 1 What effect does it have on gold ? 250 INTRODUCTION What on silver ? What on copper ? What are the oxides of platinum ? How is the peroxide obtained 1 In how many proportions does it unite with chlorine ? What characters do the salts of platinum possess ? How is fulminating platinum prepared ? What are its properties ? What is gold, and what are its properties ? In what is it soluble ? What will precipitate it from its solution ? What is the theory of the solution of gold in nitro-mur riatic acid ? How many oxides of gold are there ? Does gold combine with any other metals ? What test have you for gold ? Has mercury any affinity for gold ? What are gold coins and medals ? Illustrate this. What are the characteristics of silver ? What is the phenomenon produced by electricity upon it? What effect has the air upon it ? What are the oxides of silver ? What does silver form with chlorine ? How do you form fulminating silver ? What are its properties ? Is there any other fulminating compound ? What is the cause of the detonation ? Is silver soluble in nitric and sulphuric acids ? How can nitrate of silver be decomposed ? How are Dial plates, scales of barometers, &c. silver edr How do you form a useful solvent of silver ? TO CHEMISTRY. 251 How can Diana's tree be formed ? Where is silver found ? What is palladium ? What are its characteristics ? Is it soluble in the acids ? How is it precipitated ? What is mercury ? How is it distinguished ? How many oxides are there of this metal ? Does mercury combine with sulphur and phosphorus? What is the effect of heating hydro-sulphuret of mer- cury ? Of what is vermillion composed ? How is phosphuret of mercury formed ? What metals are soluble in mercury ? On what does the silvering of looking glasses depend ? Will sulphuric acid act upon mercury ? Will muriatic acid ? What is the action of nitric acid on mercury ? What property have the nitrates ? How is red precipitate formed ? Does mercury combine with chlorine ? What are the proportions in the protochloride and the perchloride ? Is mercury much used ? CHAP. XXVII. Of Copper—Iron—Tin—Lead—Nickel—Cadmium—Zinc 1. Copper is a metal of a peculiar reddish brown col- our, hard, ductile, malleable and sonorous, and of cofi* siderable tenacity. 252 introduction 2. It melts in a heat about sufficient to melt gold, and exhibits a bluish green flame ; by a violent heat it boils, and is volatilized, partly in a metallic state. 3. A wire one tenth of an inch in diameter will bear more than three cwt. without breaking. 4. Copper rusts on exposure to the air, but the cor- roded part is very thin, and preserves the metal below from farther corrosion. 5. There are two oxides of copper. The protoxide is of a fine orange colour, and is obtained by digesting a solution of muriate of copper with copper filings in a close vessel. The colour passes from green to dark brown, and grey crystalline grains are deposited. The solution of these yields, by potash, the protoxide. It consists of 8 copper, and -f- 1 oxygen. 6. The peroxide is of a black colour, and is procura- ble by heat, or by drying the hydrated oxide, precipitat- ed by potash from the nitrate. It consists of 8 copper -f- 2 oxygen. 7. Copper combines with chlorine in two propor- tions, forming the protochloride and the perchloride.— The protochloride consists of Chlorine, 36 or 1 prime = 4.45 35.8 Copper, 64 1 prime = 8.00 64.2 100 12.45 100.0 The perchloride consists of Chlorine, 53 or 2 primes = 8.9 52.7 Copper, 47 1 prime = 8.0 47.3 100 16.9 100.0 8. It unites with iodine, forming insoluble substances of a dark brown colour, called iodides of copper. TO CHEMISTRY. 253 9. When copper is exposed to a stream of oxygen and hydrogen gases, it takes fire and burns with great brilliancy, emitting a lively green light, of such intensity as to be scarcely endured by the eye. Copper leaves, or wire, may be burned by the galvanic fluid. 10. Copper unites with 6ulphur and phosphorus.— The sulphuret maybe formed readily, by mixing copper filings with sulphur, and making them into a paste with water. 11. The phosphuret may be formed by fusing to- gether sixteen parts of copper, sixteen parts of phospho- ric glass, and one of charcoal. 12. Copper unites with the metals and forms alloys, which are of considerable importance ; an alloy of cop- per and platinum takes a fine polish, and is not liable to rust; on this account, it has been Hsed in reflecting tele- scopes. 13. Sulphuric aciik, when concentrated and boiling, dissolves copper. If water be added to the solution, it assumes a blue colour, and on evaporation, produces crystals, called blue, or Roman vitriol, and by the present nomenclature, sulphate of copper. These are much more beautiful, if a little nitric acid be added to the solution. 14. The nitric acid acts on copper with great ener- gy, and disengages a large quantity of nitrous gas. The solution, or evaporation affords crystals of a green col- our, which are deliquescent. 15. The acetic acid acts upon copper, and forms what is called verdigris, which is a crude acetate. This, when dissolved in vinegar and evaporated, forms beauti- ful green crystals, which are subdeliquescent in the air. 16. The following acids form insoluble salts with peroxide of copper, viz. Antimonic, antimonous, bora- cic, chromic, molybdic, phosphoric and tungstic. The 22 254 INTRODUCTION first two are green, the third is brown, the fourth and fifth green, and the sixth is white. 17. The oxides of copper are poisonous; but sugar is said to be an antidote of undoubted efficacy. 1.8. Copper, with about a fourth of its weight of lead, forms pot metal ; with the same proportion of zinc, it composes brass. Mixture of zinc and copper, in differ- ent proportions, form the various compounds of Dutch gold, Prince's me^al, pinchbeck, &c. Copper and tin, with a little zinc, form bell-metal, or gun-metal. When tin is nearly one third of the alloy, it takes a beautiful polish, and is called speculum metal, from its being used in the construction of reflecting telescopes. 19. Iron is of a bluish white colour, of considerably hardness and elasticity; very malleable and exceedingly tenacious and ductile ; very easily oxidized, and difficult of fusion ; on which account, it is brought into different shapes by hammering. It possesses a property which no other metal does, except platina ; that of being weld- ed, or united by forging, after being brought to a white heat. 20. Iron cannot be hammered into leaves as thin as gold or silver, but it may be drawn into a wire as fine as a human hair; a wire one tenth of an inch in diameter, will sustain without breaking, nearly six cwt. 21. When iron is exposed to the action of moist air, it acquires weight by gradually attracting oxygen, and hydrogen gas escapes ; a yellow rust forms on the sur- face, which is not a simple oxide, as it contains a por- tion of carbonic acid. 22. Concentrated sulphuric acid scarcely acts upon iron, unless when boiling. If the acid be diluted with two or tb.rje parts of water, it dissolves iron readily, TO CHEMISTRY. 255 without Hie assistance of heat. During the solution, hy- drogen gas escapes in large quantities. 23- Green sulphate of iron is much more soluble in hot than cold water, and therefore crystallizes by cooling, as well as by evaporation. 24. The crystals are efflorescent, and fall into a white powder by exposure to a dry air; the iron becoming more oxidized than before. 25. A solution of sulphate of iron exposed to the air, acquires oxygen, and the metal being peroxidized, falls to the bottom. 26. Sulphate of iron is decomposed by alkalies and by lime. Caustic fixed alkali precipitates the iron in deep green flocks, which are dissolved by the addition of more alkali, and form a red tincture. 27. Vegetable astringent matters, such as nut-galls, the husks of nuts, logwood, hyson and souchong tea, &c. which contain tannin and gallic acid, precipitate a fine black fecula from sulphate of iron, which remains sus- pended for a considerable time in the fluid, by the addi- tion of gum arabic. This fluid is well known by the name of ink. 28. The beautiful pigment, well known in the arts by the name of prussian blue, is likewise a precipitate, afforded by the sulphate of iron and prussine, or cyano- gen. 29. Iron is soluble in nitric and muriatic acids. The former does not afford crystals on evaporation, hut de- posits the oxide of a red colour. 30. Iron combines with sulphur, phosphorus and car- bon, forming sulphurets, phosphurets and carburets of iron. Exp. If equal quantities of iron filings and sulphur are formed with water into a paste, the sulphur decom- 256 INTRODUCTION poses the wafer, and absorbs the oxygen so rapidly, that this mixture sometimes takes fire, although buried under ground. This fact is supposed to afford an explanation of the origin of volcanoes. Exp. 2. The phosphuret of iron may be formed by dropping small bits of phosphorus into iron filings heab- ed red hot. 31. The carburet of iron is found native, known un- der the name of plumbago, or black lead. It consists of about one tenth iron, the rest is carbon. 32. Cast iron is the name given to the metal when first extracted from the ores ; by heat and hammering, it is formed into what is called wrought iron. Steel is a compound of iron and carbon. 33. Iron may be distinguished from steel, by exhibit- ing a whitish grey spot with nitric acid, whereas the steel becomes black, from the carbon which it contains. 34. The yellow spots, called iron moulds, which are frequently occasioned on cloth by washing ink spots with soap, may, in general, be removed by lemon juice, or the oxalic, or nitric acid, or by muriatic acid diluted with five or six parts of water ; but in this case, the cloth should be immediately washed. 35. There are two oxides of iron, the protoxide, which is black. Its composition seems to be Iron, 100 77.82 3.5 Oxygen, 28.5 22.18 1.0 100.00 4.5 is red, it seems to be a com- 70 = 4 primes. 30,:* 3 primes. The peroxide, which pound of Iron, 100 Oxygen, 43 TO CHEMISTRY. 257 36. Iron is found in abundance in almost every part of the world, and is the most useful of all minerals. 37. Tin is a metal of a yellowish white colour, con- siderably harder than lead, scarcely sonorous, very mal- leable, though not very tenacious. Under the hammer it is extended into leaves called tin foil, which are about _j7_ 0f an inch in thickness, and might easily be beaten to less than half that thickness. 38. It is melted at a temperature about double that of boiling water, or 430° F. 39. When exposed to the air it loses its lustre, and assumes a greyish white colour ; but when melted in an open vessel, its surface very soon becomes covered with a grey powder, which is the oxide of tin. If the heat be continued, the powder becomes yellow. 40. There are two oxides of tin, the protoxide, which is grey, and the peroxide is white. 41. The protoxide consists of 13.5 per cent of oxy*- gen. The peroxide is composed of Tin, 100 Oxygen -f 27.2 And if we regard it as containing 2 primes of the lat- ter principle to 1 of metal, the prime of this will be 7.353. The mean may be taken at 7.35. 42. Tin unites with chlorine in two proportions, forming the protochloride and perchloride of tin. 43. Sulphur unites with tin in two proportions. One may be made by fusing tin and sulphur together. It is of a blue colour and lamellated texture. It consists cf 7.35 tin ami -j- 2 sulphur. The bisulphuret is made by heating together peroxide of tin and sulphur. It is of a beautiful goid colour, oaJ appears in fine flakes. It was 258 INTRODUCTION formerly called avrum mvsivum, or Mosaic gold. It con- sists, according to Dr. J. Davy, of 7.8 tin, or 1 prime tin. 4.00 sulphur, 2 primes sulphur. 44. Tin combines with various metals and forms al- loysj with mercury it forms an amalgam, which is used for electrical purposes, and silvering of mirrors. 45. The alloys of tin are used in the manufacturing of cannon, bells, and various articles made of bronze, and for reflecting telescopes. 4G. Tin plates are made by dipping plates of iron, properly scoured, into melted tin. 47. Common pins are whitened, by boiling them with tin for five or six hours in water, acidulated with tartaric acid. Brass being a compound of zinc and copper, the zinc has an affinity for the tin, and in this case, forms the union. •18. Tin is soluble in all the mineral acids, and forms sulphates, nitrates, muriates, &c, 49. When nitric acid is used as a solvent, it is decom- posed by the tin, and red fumes are thrown off with ra- pidity. Exp. Add to the nitric solution, a solution of potash. The tin decomposes both the acid and the water, the ni- trogen of the former combines with the hydrogen of the latter and forms ammonia., which is evolved in the form of gas. 50. Tin decomposes the muriate of ammonia. Exp. Put equal parts of granulated tin and muriate of ammonia into a retort, which is to be adopted to a re- ceiver, in a mercurial apparatus; as* soon as heat is ap- plied to the retort, a decomposition takes place ; the ammsnia is disengaged in the form of gas, the muriatic TO CHEMISTRY. 259 acid combines with the tin, forming a solid muriate of tin, which may be decomposed with water. 51. The muriate of tin is employed in the process of dyeing ; it is the basis of the scarlet dye. In glazing, and in the forming of Plumber's solder, tin is used. 52. Lead is a bluish white metal, very soft and flexi- ble, not very tenacious, and consequently incapable of being drawn into fine wire, but is easily extended into thin plates under the hammer. In a strong heat it boils and emits fumes, during which time, its oxidation pro- ceeds with considerable rapidity, if exposed to the air. It congeals in a crystalline form. It is not much altered on exposure to the air, though the brightness of its sur- face soon tarnishes. 53. There are two, if not three combinations of lead with oxygen. 1. The powder precipitated from the ni- trate with potash, forms the yellow protoxide. When somewhat vitrified, it constitutes litharge, and combined with carbonic acid, white lead. 2. When massicot has been exposed for about 48 hours to the flame of a rever- berating furnace, it becomes red lead, or minium. This substance has a specific gravity of 8.94. At a. red heat, it gives out oxygen and passes-to the protoxide. It con- sist of 100 lead + 11.08 oxygen. 3. If upon 100 of red lead, we digest nitric acid of specific gravity 1.26, 92.5 parts will be dissolved. But 7,5 of a dark brown pow- der will remain insoluble. This is the peroxide of lead, and consist of 100 lead, and -^ 15.4 oxygen, 54. Lead combines with chlorine and iodine ; with the former, it forms a greyish white powder; with the latter, a fine yellow. 55. The salts of lead have the protoxide for their base. 260 INTRODUCTION 56. Most of the acids attack lead ; but the sulphuric requires a boiling heat for the purpose. Nitric acid at- tacks lead with violence. Muriatic acid acts directly on lead by heat, oxidizing it, and dissolving part of its ox- ide. 57. The acetic acid dissolves lead and its oxides ; when evaporated, the solution affords needle formed crystals, called sugar of lead, from its sweet taste. 58. The common sugar of lead is an acetate ; and Goulard^s extract, made by boiling litharge in vinegar, a subacetate. The acetate crystallizes in needles, the sub- acetate in plates. Exp. Dissolve one part of sugar of lead in forty parts of water, in a phial, suspend in it a little ball of zinc, and leave it undisturbed. The zinc will soon be covered with a moss like substance, which increases gradually, shooting out into a sort of leaves, resembling in some measure, the form of a tree. The phenomenon of this depends on galvanism. 59. Oils dissolve the oxide of lead, and become thick and consistent, in which state, they are used as the basis of plasters, cements, for water works, &c. 60. Sulphur readily dissolves lead in the dry way, and produces a brittle compound, of a deep grey colour and brilliant appearance. 61. The phosphoric acid exposed to heat, together with charcoal and lead, becomes converted into phospho- rus, which combines with the metal. This combination does not differ much from ordinary lead; it is malleable, and easily cut with a knife; but is more easily tarnish- ed, when exposed to the air. 62. Oxide of lead decomposes muriate of soda, and is formed into a pigment called Patent yellow. TO CHEMISTRY. 261 Exp. Mix two parts of finely powdered red lead, with one of common salt, and form the whole into a paste with water, the alkali will be disengaged and the acid will unite with the oxide of lead. If the alkali be wash- ed off, and the mass dried and fused in a crucible, a hard heavy yellow substance will be formed. 63. Lead unites with most of the metals and forms alloys. 64. Lead is generally found in veins of rocks, com. bined with silver, antimony, sulphur, bismuth,&c When combined with sulphur, it is called galena. 65. Nickel is a metal extremely hard, of a uniform texture, and of a colour between silver and tin, very difi ficult to be purified, it is magnetical. It even acquires polarity. It is malleable both cold and red hot, and is scarcely more fusible than manganese. 66. There are two oxides of nickel, the dark ash grey, and the black. The protoxide is a compound of 100 metal and 28 oxygen. The prime equivalent of the metal will be 3.6. That of the protoxide 4.6. 67. The salts of nickel have usually a green colour, and yield a white precipitate with ferro-prussiate of potash. Ammonia dissolves the oxide of nickel. Sul- phuretted hydrogen and infusion of galls occasion a pre- cipitate. Their composition has been very imperfectly ascertained. 68. Nickel is soluble in the nitric and nitro-muriatic acids. The nitric solution has a dark green colour, and carbonate of potash throws down a green precipitate, which assumes a dark grey colour when heated "69. Nickel combines with gold, copper, iron, tin and lead. Its oxide gives a beautiful dark green colour to porcelain. 262 INTRODUCTION 70. Cadmium is a new metal discovered by Mr. Stromger; in r817T in some carbonate of zinc which he was examining, in Hanover. 71 It is a fine white metal with a slight bluish grey, approaching to that of tin, which metal it resembles in lustre and susceptibility of polish. Its texture is com- pact and its fracture hackly. It crystallizes on cooling, and presents on its surface the appearance of leaves of fern. It is flexible and yields readily to the knife. It is harder and more tenacious than tin, and stains paper and the fingers. It is ductile and malleable, but when long hammered flies off in scales. It melts and is volatilized at a red heat. Its vapour may be condensed in drops like mercury, and exhibits traces of crystallization. 72. There is but one oxide of Cadmium, which con- siststs of 100 of metal combined with 14.352 of oxy- gen. 73. It is soluble in liquid ammonia and the acids* 74. Cadmium unites easily with most of the metals and forms alloys ; which are brittle and colourless. 75. Zinc is a metal of a bluish white colour, some- what brighter than lead, of considerable hardness and so malleable as not to be easily broken by the hammer. It is very easily extended by the rollers of the flatting mill- When broken by bending, its texture appears as though composed of cubical grains. It melts at about 700° F and soon after it becomes red hot, it burns with a dazzling white flame of a bluish yellow tinge, and is oxidized with such rapidity that it flies up in the form of white flowers called flowers of zinc. 76. There is but one oxide of zinc which consists of 100 metal -4-2.41 oxygen. The prime equivalent appears to be 4.1. IX) CHEMISTRY. 263 77. Zinc combines with chlorine and forms a substance of a whitish grey colour, and semi-transparent. 78. Most of the acids dissolve zinc and form salts; sulphate of zinc or white vitriol is much used in the arts. 79. Zinc will decompose nitric acid. Exp. Put some granulated zinc in a Florence flask, and pour over it weak nitric acid; a strong effervescence ensues, and nitrous gas is disengaged. 80. Zinc is obtained from Lapis Calaminaris and other minerals. 81. It is used in making brass, in forming amalgams for electrical purposes, &c. Zinc filings are -mixed with gunpowder to produce the brilliant stars in artificial fire- works. PRACTICAL QUESTIONS. What is Copper ? What heat is required to melt and cause it to boil? How much will a wire 1 10th of an inch in diameter bear? What effect does the air have on copper ? What are the oxides of copper ? What is the pertoxide ? How many chlorides are there ? What is the iodide ? What is the effect when copper is exposed to a stream of oxygen and hydrogen gases 1 Does copper unite with sulphur? How do you form the phosphuret? Does copper unite with the metals ? Does sulphuric acid dissolve copper? What effect has nitric acid on copper? 264 INTRODUCTION What is the action of acetic acid on copper ? What acids form insoluble salts with peroxide of cop- per? Are the oxides of copper poisonous ? What are the different alloys of copper ? What is iron ? What is the ductility of iron ? What is the effect of moist air on iron ? Does concentrated sulphuric acid act upon iron ? What is the solubility of green sulphate of iron? What effect does air have on sulphate of iron? How is sulphate of iron decomposed ? What effect has vegetable astringents on iron ? What is Prussian blue ? Is iron soluble in nitric and muriatic acids ? Does iron combine with sulphur, phosphorus and car- bon ? What is Plumbago ? What is Cast iron ? How do you distinguish iron from steel ? How can iron mould be removed from cloth ? How many oxides of iron are there ? What are their compositions ? Where is iron found ? What is tin ? What heat is required to melt it? What effect does the air and heat have upon it? How many oxides are there ? What are their proportions ? How many combinations has tin with chlorine f How many proportions with sulphur ? Is tin alloyed with any of the metals? For what are the alloys used?' How are tin plates made ? TO CHEMISTRY. 265 How are pins whitened ? Is tin soluble in the mineral acids ? What effect has tin on the nitric acid-? Does tin decompose ammonia ? Illustrate it. What use is the muriate of tin ? AVhat is lead ? How many oxides of lead are there ? Does lead combine with chlorine and iodine ? What have the salts of lead for their base 1 Have the acids any effect on lead ? What is sugar of lead ? How is a lead tree formed, and what is the cause ? What effect have oils on the oxides of lead? What effect has sulphur on lead ? What effect has the phosphoric acid ? What is Patent yellow ? Does lead unite with the other metals ? Where is lead found ? What is Nickel ? How many oxides of nickel are there ? What do the salts of nickel exhibit ? In what acids is nickel soluble ? With what does nickel combine ? What is Cadmium ? What are its properties ? How many oxides are there ? In what is it soluble ? Does it unite with the metals? What is zinc ? What are the oxides of zinc? Does Zinc combine with chlorine ? 23 266 INTRODUCTION Do the acids dissolve zinc ? From what is zinc obtained' For what is it used ? CHAP. XXVIII. Vf Bismuth—Antimony—Manganese—Coba It—Tellurium 1. Bismuth is a metal of yellowish, or reddish white colour, little subject to change in the air. It is somewhat harder than lead, and is not malleable. Its fracture ex- hibits large shining plates, disposed in a variety of posi- tions ; thin pieces are sonorous. It melts at a tempera- ture of 480° F. and its surface becomes of a greenish grey or brown oxide. A stronger heat ignites it, and causes it to burn with a small blue flame, at the same time a yellowish oxide known by the name of flowers of bismuth is sublimed. This oxide appears to rise in conse- quence of the combustion, for it is very fixed, and run? into a greenish glass when exposed to heat alone. 2. This oxide consists of 1-00 metal-}-11.275 oxygen. Its prime equivalent will be 9.87, and that of the inetrii itself, 8.87. The specific gravity of the metal 9.85. 3. The sulphuric acid has a slight action on bismutbj when it is concentrated and boiling. Sulphurous acid gas is evolved, and part of the bismuth is converted into a white oxide. A small portion combines with the sulphur- ic acid and forms a deliquescent salt in the form of small needles. 4. The nitric acid dissolves bismuth with the great- ;e>t rapidity and violence; at the same time, much heat TO CHEMISTRY. 2(}7 is extricated, and a large quantity of nitrous oxide is dis- engaged. The solution when saturated, affords crystals as it cools. The salt detonates weakly and leaves a yellow oxide behind, which deliquesces in the air. Exp. When the nitric solution is diluted with pure water, the metal falls down in the form of a white oxide called, formerly, Mugestery of bismuth This affords a test by which bismuth is distinguished from the other me- tals. < 5. The muriatic acid does not readily act upon bis- muth. 6. Chlorine acts so violently on bismuth as to cause it to take fire. The substance formed is chloride of bis- muth, formerly called butter of bismuth. 7. Iodine combines with bismuth and forms an iodide of an orange yellow colour. 8. Sulphur combines with bismuth in two proportions, forming sulphurets. 9. Bismuth combines with most metals and render? them more brittle. 10. Bismuth is used in the formation of printers' small types, and to make pewter. It forms the bases of a sym- pathetic ink. In this experiment the acetic acid must be employed for the solution of the metal. Characters written with this solution become vis:ble,when exposed to sulphuretted hv drogen. 11. The term Antimony is used to denote in com- merce a metallic ore consisting of sulphur combined with the metal. It consists of about 26 per cent of anti- mony. 12. Antimony when pure, is of a dusky white colour, very brittle, and of a plated or scaly appearance, the plates crossing each other in every direction. 1.3. It may be obtained in the form of a metal from 268 INTRODUCTION the sulphuret, by fusing three parts in a covered crucible, with one of iron filings; or by fusing it with animal char- coal. The product was formerly called regulus of Anti- mony. 15. It requires for its complete fusion a heat near- ly 450° F. 15. There are three if not four combinations of an- timony with oxygen. In 100 part' The protoxide consists of 11 metal + 1 oxy. or 9lf + 8.', Deutoxide 11 + 2 81.6 + 15.1 Tritoxide 11 +3 78.6+21.4 Peroxide 11 +4 73.4 + 36.6 16. Antimony looses its lustre in the air; but it is not altered by being kept under water. When steam is made to pass over red hot antimony, it is decomposed so rapid- ly that a violent detonation ensues. 17. When the native sulphuret is slowly roasted, it gradually loses its sulphur, the metal attracts oxygen, and is converted into a grey oxide, this being fused by a strong heat, runs into a glassy substance and is called the glass of antimony. 18. If the native sulphuret be reduced to powder and boiled with pure potash, the solution deposits on cooling an hydro-sulphuret, formerly called kermes mineral. A similar compound with a larger proportion of sulphur was formerly called golden sulphur of antimony. 19. Antimony combines with other metals and forms alloys ; between six and seven parts of lead and one of antimony form an alloy of which printer's types are made. Sometimes, however, a less quantity of antimony is used. TO CHEMISTRY. 269 20. Antimony combines with the acids and forms salts which have been much used in medicine, especially that of tartaric acid and antimony called tartar emetic, (tar- trate of antimony.) The white deutoxide of antimony is the bases of this salt. 21. The empirical medicine called dames'* powder is a compound of which antimony is the principal ingre- dient. 22. Antimony is obtained from an ore which is abund- ant in some parts of the world, prrticularly in Germany and Norway. 23. Manganese is a metal of a dull-whitish colour when broken, but which soon grows dark by oxidation from the action of the air. 24. It is hard, brittle, though not pulverizable, and rough in its fracture. It is so difficultly fusible, that no heat, hitherto exhibited, has caused it to run into masses of any considerable magnitude. When broken into pie- ces it falls into powder by spontaneous oxidation. 25. Manganese heated in oxygen or chlorine, takes fire and forms an oxide or chloride. 26. Chemists differ with regard to the number of combinations with oxygen. Sir H. Davy has two, M. Thenard, four, Mr. Brande, three, and Berzelius, five. The black oxide is the state in which it is usually found. 27. Manganese is soluble in the acids, but most readi- ly in the nitric. It is precipitated by alkalies in the form "of white powder. It combines with the other me- tals and is scarcely ever found, but when mixed, more or less, with iron. 28. When powdered manganese and nitrate of potash are mixed together and thrown into a red hot crucible, 23* ' 270 INTRODUCTION the nitrate is decomposed, and a highly oxidized manga- nese with potash is obtained, which has the following properties. It exhibits different colours,according to the quantity of water that is added to it. A small quantity gives a green solution, a little more changes it to blue . some more gives it a purple. The experiment may be Varied by putting equal quantities of this substance into two glass vessels, and pouring on the one hot, and on the other cold water, the same material with water of differ ent temperatures assumes various shades of colours, and on that account it has been called the chameleon mineral. 29. Manganese in a state of oxide has been found in different parts of the World. It is very abundant in some parts of the United States, and is of an excellent quality. It is used in bleaching and in the manufacture of glass. 30. Cobalt is a brittle, somewhat soft but difficultly fusible metal, of a reddish grey colour, of little lustre. It melts at 130° Wedg. 31, Cobalt is susceptible of magnetism, but in a lower degree than that of nickel. 32. Oxygen combines with cobalt in two proportions, forming a dark blue protoxide, and a black perox- ide. The first dissolves in acids without effervescence. It consists of cobalt, 5.4 100 84.33 oxygen, 1.0 18.5 15.62 100.00 The peroxide, cobalt, 5.1 100 73 oxygen, 2.0 37 27 100 TO CHEMISTRY. 271 33. When cobalt is heated in chlorine it takes fire and forms the chloride. 34. The best solvents of this metal are the nitric and nitro-muriatic acids. From these solutions sympa- thetic inks are formed. Exp. Digest one part of cobalt in a sand heat for some hours, with four parts of nitric acid, to the solution one part of the muriate of soda is to be added, and four purls of water. Write with this solution,, when cold they will be illegible ; but on applying a gentle heat they as- sume a beautiful blue or green colour. 35. Cobalt combines in small proportions with most of the acids, also with ammonia, phosphorus and most of the metals. It is found mineralized with arsenic. 36. Cobalt is found in England, Germany and the United States. 37. Tellurium is a metal found in the state of an ore in Transylvania. 38. Pure tellurium is of a tin white colour, verging to lead grey, with a high metallic lustre ; of a foliated fracture, very brittle, so as to be easily pulverized. It melts before ignition, at a temperature nearly that at which lead fuses. It burns on charcoal, before the blow pipe, with a vivid blue 'flame, greenish on the edges, and is dissipated in greyish white vapours, of a pungent smell which condense into a white oxide. 39. Tellurium is oxidized and dissolved by the prin- cipal acids. 40. It unites with sulphur, and forms a lead coloured striated sulphuret. 41. Tellurium and hydrogen combine to form a gas, called telluretted hydrogen. It may be formed in the fol- lowing manner. Hydrate of potash and oxide of telluri- um are ignited, together with charcoal, and the mixture £72 INTRODUCTION acted upon by diluted sulphuric acid, in a retort connect- ed with a mercurial pneumatic apparatus ; an elastic fluid is generated, consisting of hydrogen holding tellu- rium in solution. The telluretted hydrogen is soluble in water and forms a claret coloured solution. It com- bines with the alkalies. It burns with a bluish flame, depositing oxide of tellurium. Its smell is very strong and peculiar, resembling in some measure, sulphuretted hydrogen. Its specific gravity is 2.2916. PRACTICAL QUESTIONS. What is bismuth, and its properties ? What is the proportion of oxygen in bismuth ?': Does the sulphuric acid act on bismuth ? What action has the nitric acid ? Does the muriatic acid act upon it ? What is the action of chlorine ? Of iodine ? Does sulphur combine with bismuth ? Does bismuth combine with any of the metals I. What is the use of bismuth ? What is antimony ? What are its properties ? How can it be obtoined from the sulphuret ? What heat does it require for its fusion, and how many combinations has it with oxygen ? Does the air have any effect upon it ? What is the glass of antimony ? What is Kerrnes'' Mineral ? Does antimony combine with any other metal ? Does autimony combine with acids ? What is Jameses powder ? From what is antimony obtained ? What is manganese ? TO CHEMISTRY. 273 What are its characteristics ? What is the effect of heating manganese in oxygen or chlorine ? What are the number of combinations with oxygen ? Is manganese soluble in the acids ? How is the chameleon mineral formed ? Where is manganese found ? What is cobalt ? Is it susceptible of magnetism ? How many combinations of oxygen are there ? What is the effect of heating cobalt in chlorine $ What are the solvents of this metal ? How is a sympathetic ink prepared with cobalt ? Does cobalt combine with the acids and alkalies ? Where is cobalt found ? What is tellurium ? What are its characteristics ? How is tellurium oxidized and dissolved ? Does it combine with sulphur ? What is the combination of tellurium and hydrogen ? CHAP. XXIX. Of Arsenic—Chromium—Molybdenum—Tungsten—Colum- bium—Selenium—Osmium. 1. Arsenic is a metal of a bluish white colour, subject to tarnish, and grow first yellowish, then black, by expo- sure to the air. It is brittle, and when broken exhibits a lamellated texture. In close vessels it sublimes entire at 356° F. but burns with a small flame in contact with nxygen. 274 INTRODUCTION 2. What is called arsenic in the shops is a white ox- ide of arsenic. 3. Arsenic is among the most combustible of the metals; it burns with a bluish flame, exhales the smell of garlic, and sublimes in the state of arsenious acid. 4. Concentrated sulphuric acid does not attack arse- nic when cold ; but if it be boiled upon this metal, sul- phurous acid gas is emitted, a small quantity of sulphur sublimes, and the metal is reduced to an oxide. 5. Nitrous acid readily attacks arsenic, and converts it into arsenious acid, or if it be employed in considera- ble quantities into arsenic acid. 6. Boiling muriatic acid dissolves arsenic, but affects it very little when cold. This solution affords precipi- tates on the addition of alkalies. The muriatic solution when condensed in a close vessel and sublimed, forms butter of arsenic. Thrown in powder into chlorine, it burns with a bright white flame, and is converted into a chloride. 7. None of the earths or alkalies act upon it unless it be boiled a long time, in a fine powder, in a large pro- portion of an alkaline solution, 8. Arsenic readily combines with sulphur by fusion and sublimation, and forms a yellow compound, called orpiment, or a red, called realgar. 9. Arsenic is soluble in fat oils in a boiling heat. It unites with metals, and forms alloys. 10. Iodine and arsenic unite, and form .an iodide of a dark purple red colour, possessing the properties of an acid. It is soluble in water,, and its solution forms a solu- ble compound with potash. 11. A mixture of oxymuriate-of potash and arsenic forms a compound, which takes fire with great rapidity TO CHEMISTRY. £75 Exp. Mix the oxymuriate and oxide of arsenic by Stirring them together on paper, with the point of a knife. If two trains be laid on the table, one of gun- powder, the other of this mixture, and then brought in contact with each other at one end, so that they may be fired at once, the arsenical mixture burns with the ra- pidity of lightning, while the gunpowder comparatively slow. 12. Arsenic destroys the magnetic property of iron and nickel. 13. Arsenic in its metallic state enters into the com- position of several alloys forthe formation of specula.— It is used in making small shot, to render the lead more capable of running into grains. It is employ- ed like many other metals, in dyeing and calico printing; it enters into composition of some sorts of glass, and it forms several excellent pigments. 14. Arsenic is a most deadly poison, the best antidote for which, is the sulphuret of potash. 15. Chromium is a metal extracted either from the native chromate of lead, or iron. The latter being most abundant, is generally used. 16. It is a porous mass of agglutinated grains. It is very brittle, and of a greyish white, intermediate be-< tween tin and steel. It is sometimes obtained in needle formed crystals, which cross each other in all directions. It is susceptible of a feeble magnetism. It resists all the acids except the nitro-muriatic, which, at a boiling heat, oxidizes it and forms a muriate. 17. Chromium is capable of combining with three portions of oxygen. 18. The protoxide is green, infusible, undecompouhd- ed by heat, reducible by voltaic electricity, and not act- ed upon by the air. *76 INTRODUCTION 19. The deutoxide is a brilliant brown powder, inso- luble in acids, and scarcely soluble in alkalies. Muriatic acid digested on it, exhales chlorine. 20. The peroxide is the chromic acid. 21. The chromic acid is found combined with iron in considerable quantity, near Baltimore ; from this, the beautiful pigment, called chromic yellow is prepared. 22. Molybdenum is a metal which has not yet been reduced into masses of any magnitude ; but has only been obtained in small separate globules, in a blackish brilliant mass. 23. The globules are grey, brittle, and extremely Infusible. By heat it is converted into a white oxide, which rises in brilliant needle formed flowers, like those of antimony. Nitric acid readily oxidizes and acidifies the metal. Nitre detonates with it, and the remaining alkali combines with its oxide. 24. Molybdenum unites wjlh several of the metals, and forms brittle or friable alloys. No acid acts upon it but the nitric and nitro muriatic ; but several acids act on its oxide, and afford blue solutions. 25. When molybdate of ammonia is ignited in a cru- cible with charcoal powder, it is converted into'the pro- toxide of the metal, of a brown colour, crystallized ap- pearance.. The deutoxide is the molybdous acid, and the tritoxide the molybdic acid. Exp. A small rod of zinc or pure tin is acted upon by a solution of the acid, which becomes blue in consequence ff the loss of a portion of the oxygen. 26. Tungsten is a metal obtained from a mineral ^bund in Sweden; in its metallic state, it is somewhat like iron, and is rather brilliant. It is one of the hard- est of all metals, and the heaviest, except gold and plati num. It requires a very high temperature for its fusion. TO CHEMISTRY. It is not acted upon by the magnet. When heated in an open vessel, it absorbs oxygen from the atmosphere, and is converted into an oxide. 27. There are two oxides of tungsten, the brown and the yellow, or tungstic acid. 28. The brown or protoxide has a flea brown col- our, and when heated in the air, it takes fire and burns like tinder, passing into tungstic acid. The protoxide consists of Tungsten, 100 Oxygen, 16.6 29. When heated with chlorine, tungsten burns with a deep red light, and forms an orange coloured volatile substance, which, when decomposed with water, forms the yellow oxide and muriatic acid. 30. Columbium is a metal first discovered in a miner- al found in the British Museum, said to have been sent from Massachusetts, with some ores of iron. The min- eral is said to be a columbiate of iron, that is, to consist of one part oxide of iron, and three parts of a white col- oured substance, which possesses the properties of an acid, called columbic acid. 31. It is procured from the oxide in the form of me- tallic grains, which are so hard as to scratch glass, and are easily pulverized. Neither nitric, muriatic, nor ni- tro muriatic acids have any action upon it, though di- gested on it for several days. It has been alloyed with iron and tungsten. 32. Columbium is known to be the same as the metal found in yttro tantalite, a mineral of Sweden, and former- ly called tc".talittm. 33. Sele,i,um is an elementary body, extracted by M. Berzelius from the pyrites of Fahlun, which, from its chemical properties, he places between sulphur and tel- 24 278 INTRODUCTION lurium, though it has more properties in common with the former than the latter substance. 34. When selenium, after being fused, becomes solid, its surface assumes a metallic brilliancy of a very deep brown colour. Its fracture is conchoidal, vitreous, of the colour of lead, and perfectly metallic. Its powder has a deep red colour, but it sticks together readily when pounded, and then assumes a g^ey colour and smooth surface, like antimony and bismuth. In very thin pieces it is transparent, with a ruby red colour. When heated, it softens ; and at 212° it is semi-liquid, and melts com- pletely at a temperature a few degrees higher. During its cooling it retains for a long time a soft state. In this state it may be kneaded between the fingers and drawn out into long threads, which have considerable transpar- ency; if viewed by transmitted light, they arc red ; but by reflected light, they are grey, and have the metallic lustre. 35. Selenium is not a good conductor of caloric. It is also a non-conductor of electricity. 36. Its affinity for oxygen is feeble, when heated in the air, without coming in contact with a burning body, it is volatilized with a strong smell of horse radish. The odorous substance is a gaseous oxide of selenium. 37. By heat in a large flask, filled with oxygen, sele- nium combines with the oxygen, and forms a substance which possesses the property of reddening litmus paper, called selenic acid. 38. Sulphur, phosphorus, the earths, and the metals, combine with selenium, forming seleniurcts. 39. Osmium is a metal discovered in the ore of pla- tina, which has a peculiar and pungent odour, resembling that of chlorine gas, whence it had its name. TO CHEMISTRY. 279 40. It is of a dark grey or blue colour, of some me- tallic lustre, infusible when excluded from the air, but •easily oxidized, when heated in contact with it. It is not soluble in any of the acids. Its oxide forms a 3rellow solution with potash. 41. The pure metal forms with gold and silver mal- leable alloys. 42. The best test for the oxide of osmium is an infu- sion of galls, which soon becomes of a purple colour, and afterwards changes to a vivid blue. PRACTICAL QUESTIONS. What is arsenic ? Is this the arsenic of the shops ? Does sulphuric acid act on arsenic ? What effect has the nitrous acid ? What effect has muriatic acid ? Do the earths and alkalies act upon it ? Does it combine with sulphur ? Does it unite with the oils and metals ? Does it unite with iodine ? What*is the effect of mixing oxymuriate of potash with arsenic ? What effect does if have on iron ? Of what use is arsenic ? What is an antidote for its poison ? What is chromium ? What arc its characteristics ? With how many portions of oxygen will chromium combine ? What is the protoxide ? What is the deutoxide ? What is the tritoxide or peroxide ? Where is it found ? 280 INTRODUCTION What is molybdenum ? What are its properties ? Does molybdenum unite with any of the metals T What are the oxides of molybdenum ? What is tungsten ? What are the oxides of tungsten ? Wrhat is the protoxide ? What is the effect of heating tungsten with chlorine ? What is columbium ? How is it procured ? What is selenium ? Is selenium a conductor of caloric and electricity ? What is its affinity for oxygen ? What is selenic acid ? What are seleniurets ? What is osmium ? What are its characteristics ? Does it unite with the metals ? What is the best test for osmium ? CHAP. XXX. Of Rhodium---Iridium— Uranium— Titanium—Cerium— JVodanium. 1. Rhodium is a metal discovered in the ore of pla- tinum. 2. It is not malleable. It unites with all the metals, except mercury. When alloyed with three times its weight of bismuth, copper or lead, the substances may be completely dissolved in a mixture of two parts by TO CHEMISTRY. 231 measure of muriatic acid, and one of nitric. When lead is used, it is reduced by evaporation to an insoluble mu- riate, which then exhibits the rose colour ; from which circumstance, the name of the metal is derived. It is soluble in'alcohol. 3. Iridium is likewise extracted from the ore of pla- tinum, and is so named from the variety of colours ex- hibited in the oxide. It has been obtained in a state of purity, by heating the muriate, which expelled the acid and oxygen. It is of a white colour, and perfectly infu- sible. 4. It unites with many of the metals, forming al- loys. 5. It unites with sulphur and forms a sulphuret, which is of a black colour, and consists of 100 iridium and 33.3 sulphur. 6. Uranium is a metal discovered in a mineral, called Pechblende, where it exists in a state of sulphuret. It likewise occurs in the state of an oxide in green mica, and in the uranochre. 7. Uranium is of a dark grey colour inclining to brown ; it is obtained in grains, forming a porous mass. It requires a stronger heat to fuse it than manganese. 8. There is probably but two oxides of uranium ; the protoxide, which is greyish black ; and the perox- ide, which is yellow. 9. The oxide is soluble in dilute sulphuric acid, gently heated, and affords lemon coloured prismatic crys- tals. Its solution in muriatic acid, in which it is but im- perfectly soluble, affords yellowish green rhomboidal tablets. Phosphoric acid dissolves it, but after some time, the phosphate falls down in a floculent mass, of a pale yellow colour. 24* 282 INTRODUCTION 10. It combines with verifiable substances, and gives them a brown or green colour. With the usual flux, on porcelain, it produces an orange colour. 11. Titanium is a metal originally discovered in Corn- wall, Eng. and first called Menachanite. It is found also in a mineral, called red schorl, or tilanite. 12. It is in the form of agglutinated friable masses.— Crystallized, internjilly of a brilliant red. Infusible, un- alterable by water. Soluble in boiling sulphuric, muri- atic and nitric acids. 13. It tarnishes on exposure to the air, and is oxi- dized when heated in contact with it. 14. Titanium combines with three portions of oxy- gen. The protoxide is blue, the deutoxide red, and the peroxide white. 15. It unites with phosphorus, forming a pale white compound of a metallic lustre, of a brilliant and granu- lated texture. It unites with iron, and forms an alloy. 16. Cerium is a metal discovered by Hisinger and Ber- zelius, in a mineral found in a Swedish copper mine. 17. To procure the oxide of cerium is easy ; but all attempts to reduce that oxide to a metallic state have failed. The metal appears to be volatile, and is dissi- pated by a violent heat, while a moderate heat is not sufficient to reduce it. 18. Cerium appears to be white and brittle. 19. It is capable of two stages of oxidation, the white and the red. 20. Alkalies do not act upon it ; but caustic potash in the dry way, takes part of the oxygen from the red oxide, so as to convert it into the white, without altering its nature. 21. The oxides of cerium are soluble in the min- eral acids, and form salts, which are of a white or yel- low colour, and a sweetish taste. TO CHEMISTRY. 283 22. The white oxide unites directly with tartaric acid, but requires an excess to render it soluble. 23. Wodanium is a metal recently discovered in Wod- an pyrites, a mineral of Hungary, and so named from Woden, or Wodan, an ancient German deity. 24. It has a bronze yellow colour. It is malleable ; its fracture is hackly ; it has the hardness of fluor spar; and is strongly attracted by the magnet. 25. It is not tarnished by exposure to the atmosphere at a common temperature; but when heated, it is con- verted into a black oxide. 26. The solution of this metal in acids is colourless, or at least has only a wine yellow tinge. Its hydrated carbonate is white. The hydrate precipitated by car- bonate of ammonia is indigo blue. 27. Neither the alkaline phosphates nor arseniates, occasion any precipitate, when dropped into a saturated solution of the metal in an acid. Infusion of galls, like- wise, produces no precipitate. A plate of zinc throws down a black metallic powder from the solution of this metal in muriatic acid. Prussiate of potash throws down a pearl grey precipitate. 28. Nitric acid dissolves with facility both the metal and its oxide, and the solution yields colourless needle form crystals, which readily dissolve in water. PRACTICAL QUESTIONS. What is rhodium ? What are its characteristics ? What is iridium ? Does it unite with any of the metals ? Does it unite with sulphur ? What is uranium ? How many oxides are there of uranium ? 284 INTRODUCTION In what is the oxide soluble ? With what does the oxide combine ? What is titanium ? What are its characteristics ? What effect has the air upon it ? How many oxides are there of titanium ? With what does it unite ? What is cerium ? Is it procured in a metallic state ? What are its characteristics ? With how many portions of oxygen does it combine ? Do alkalies act upon it ? In what are the oxides of cerium soluble ? Does the white oxide unite with tartaric acid ? What is wodanium ? What are its characteristics ? What effect has the air upon it ? What are the solutions of this metal in acids ? How is it precipitated from its solutions ? What effect has nitric acid upon it ? CHAP. XXXI. Of Prussine, or Cyanogen. 1. Prussine, or prussic gas, is what M. Gay Lussac terms cyanogen ; a word derived from the Greek, and literally signifies a producer of blue. But the production of blue can never be the effect of this substance on any other single body; but an indirect operation of it in con- junction with iron, hydrogen and oxygen- This action has not been fully explained. TO CHEMISTRY. 285 2. As this substance does not directly produce blue with iron, many chemists have relinquished the term cy- anogen, and as this substance, like chlorine and iodine, by its action on potassium produces flame, and like them is acidified by hydrogen, the term prussine is thought to be more appropriate. 3. This substance was discovered and examined by M Gay Lussac. 4. By digesting red oxide of mercury with prussian blue, a cyanide or prusside may be obtained, perfectly neutral, which crystallizes in long four sided prisms, trun- cated obliquely. By repeated solutions and crystalliza- tions, it may be freed from a small portion of iron which adheres to it Or it may be boiled with red oxide of mercu- ry and the iron will be precipitated. The excess of oxide of mercury must be saturated with a little prussine or muriatic acid. The prusside thus formed is decomposed by heat to obtain the radical. 5. When the cyanide is boiled with the red ox" ide of mercury, it dissolves a considerable quantity of the oxide, becomes alkaline, crystallizes no longer in prisms but in small scales, and its solubility in water appears a little increased. When evaporated to dryness, it is very easily charred, on this account it is necessary to employ the heat of a water bath. 6. When the compound is decomposed by heat, it gives abundance of prussine mixed with carbonic acid gas. The prusside of mercury, when neutral and very dry, produces prussine ; but when moist, it furnishes only car- bonic acid, ammonia and a large quantity of prussic acid vapour. 7. When the prusside is used with excess of the pe- roxide, the same products are obtained, but in differ- 286 INTRODUCTION- ent proportions, together with azote and a brown liquid. 8. To obtain pure prussine, the neutral prusside must be used in a state of perfect dryness. The other mercu- rial compound, is not, however, a sub prusside simply ; but a compound of the oxide of mercury and the prus- sine ; analogous to the brick coloured precipitate obtain- ed by adding a little potash to the deuto-chloride of mer* cury, corrosive sublimate, which is a triple compound of chlorine, oxygen and mercury; or a binary compound of oxide of mercury and a chloride of that metal. These compounds may be called oxy-prusside and oxy-chloride of mercury. 9. When the neutral simple mercurial prusside is ex- posed to heat in a small glass retort, or a tube closed at one end, it soon begins to blacken; appears to melt like an animal matter, and the prussine is disengaged in abundance. This gas, from the commencement of the process to the end, is pure; care must be taken, howev- er, not to raise the heat too high, so as to melt the glass. in that case a little azote will be disengaged. Observation. In this process mercury is sublimed with a considerable quantity of prussine, and there remains a charry matter, very light, and spongy, of the colour of soot. 10. The prusside of silver gives out prussine when heated, but that of mercury is preferable and is more economical. 11. Prussine is a permanently elastic fluid. Of a pe- culiar and penetrating smell. Soluble in water and im" parts to it a very sharp taste. The gas is combustible, and burns with a bluish flame, mixed with purple. Its specific gravity compared with that of air is 1.8064. 100 cubic inches weigfh 55.1295 grains. TO CHEMISTRY. • 28*7 12. Prussine is capable of sustaining a pretty high temperature without decomposition. 13. Water absorbs about 4 1-2 times its volume. 14. Sulphuric acid and oil of turpentine dissolve prussine in the same quantity as water. 15. Prussine reddens tincture of litmus. On heating the solution the gas is disengaged, mixed with a little carbonic acid, and the blue colour of the litmus is restor- ed. It is probable that the carbonic acid proceeds from decomposition of a small quantity of prussine and water. 16. Prussine destroys the colour of red sulphate o manganese, a property which is not possessed by prussic acid. Which is a proof of the superior activity of its el- ements. In the dry way, it separates the carbonic acid from the carbonates. 17. Phosphorus, sulphur and iodine may be sublimed in prussine without producing any change on it. Its mix- ture with hydrogen was not altered by the same tempe- rature, or by passing electric shocks through it. 18. Copper and gold do not combine with prussine ; but iron, when heated almost to whiteness, partially de- composes it. The metal is covered with a slight coating of charcoal and becomes brittle. The undecompounded portion of the gas is mixed with nitrogen, it constitut- ed in one trial 0.44 of the mixture; but in general it was less. Platinum which had been placed .at the side of the iron did not undergo any chunge ; neither its surface nor that of the tube was covered with charcoal. 19. Potassium acts but slowly on prussine in the cold, because a crust is formed on its surface which prevents the mutual action. On applying to the substance a spir; it lamp, the potassium speedily becomes incandescent, 288 INTRODUCTION the absorption of the gas commences, the inflamed disc gradually diminishes, in a few seconds it disappears en- tirely, and the absorption is at an end. 20. If a quantity of potassium be employed which will disengage 50 parts of hydrogen from water, it wil' be found that 48 or 50 parts of hydrogen will have dis- appeared. On treating the remainder with potash, there usually remains 4 or 5 parts of hydrogen, sometimes 10 to 12. 21. The compound of prussine and potassium is yel- lowish. It dissolves in water without effervescence and - the solution is strongly alkaline. Its taste is the same as hydro cyanate of potash, of which it partakes of the properties. 22. Prussine is very inflammable when exploded with about 2i times its volume of oxygen. The detonation is very powerful, and the flame is bluish, like that of sulphur burning in oxygen. 23. If 100 parts of prussine be exploded, a diminution of volume takes place, which, when measured, is found to be from four to nine parts. When the residuum is treated with potash or barytes, it diminishes from 195 to 200 parts, which are carbonic acid gas. The new resi- duum analyzed over water by hydrogen, gives from 94 to 98 parts of nitrogen, and the oxygen which it contains, added to that in the carbonic acid is nearly equal to that which has been employed. 24. From the above experiment it may be inferred that prussine contains a sufficient quantity of carbon to produce twice its volume of carbonic acid gas ; that is, two volumes of the vapour of carbon with one of nitrogen condensed into a single volume. 25. If the above supposition be correct, the density of the radical derived from it ought to be equal to the den- TO CHEMISTRY. 289 eity derived from experiment; but supposing the density of air to be 1.00 twice that of the vapour of By experiment. Carbon is 0.8320 0.8332 Nitrogen 0.9691 0.9722 1.8011 1.8054 26. By adding a volume of hydrogen to a volume of prussine, we obtain two volumes of prussic acid vapour, in the same way as by adding a volume of hydrogen to a volume of chlorine we obtain two volumes of muriatic acid gas. The same proportions hold with regard to the vapour of iodine, hydrogen and hydriodic acid. Hence it follows that the specific gravities of these acids are ex- actly equal to half the sum of the densities of their res- pective bases and hydrogen. 27. M. Gay Lussac having introduced prusside of mer- cury into a glass tube, covered it with brown oxide of copper,and then raised the heat to a dull red. On heat- ing gradually the part Of the tube containing the piusside it was gradually disengaged, passed through the oxide and the metal was completely reduced. On washing the gaseous products with a solution of potash, at different parts of the process, he obtained only from 0.19 to 0.30 of azote ; instead of 0.33, which ought to have remained according to his former analysis. Presuming that some nitrous compound had been formed, he repeated the ex- periment, covering the oxide with a layer of copper fil- ings which he kept at the same temperature as the ox- ide. With this new arrangement, the results were very singular, for the smallest quantity of nitrogen which he obtained during the whole course of the experiment was 25 290 INTRODUCTION • '2,7 for 100 of ga*, and the greatest was 34.4. The -mean of all the trials was Nitrogen 33.6 or nearly 1 Carbonic acid 66.4 " 2 100.00 This shews that prussine contains two volumes of the the vapour of carbon, and one volume of azote or nitro- gen. 28. In another experiment of Gay Lussac's instead of passing the prussine through the oxide of copper, he made a mixture of one part of the prusside of mercury, and 10 parts ofthe red oxide ; after introducing it into a glass tube closed at one end, he covered it with copper filings, which he raised first to a red heat. On heating the mix- ture successively, the decomposition went on with facility, the proportions ofthe gaseous mixure were less regular than in the proceeding experiment Their mean was Nitrogen 34.6 instead of 33.3 Carbonic acid 65.1 " 66.7 100.0 hi another experiment he obtained Nitrogen 32.2 Carbonic acid 67.8 100.0 Now the mean of these results gives Nitrogen 33.4 Carbonic acid 66.6 100.0 TO CHEMISTRY. 291 This shows that what has been considered as a prus- siate of mercury, is in fact a prusside. 29. When a pure solution of potash, not too concen- trated, is introduced into prussine, a rapid absorption takes place. If not quite saturated, it is scarcely tinged of a lemon yellow colour. But if the prussine be in ex- cess, we obtain a brown solution, apparently carbona- ceous. 30. On pouring potash combined with prussine into a solution of protoxide of iron, and adding an acid, we ob- tain Prussian blue. At first it appears that the prussine is decomposed in this experiment, at the moment that it combines with potash, but this is doubted, for when this body is really decomposed by means of an alkaline so- lution, carbonic acid is produced, together' with prussic acid and ammonia. But in pouring a solution of barytes into a solution of prussine in potash, no precipitate is formed, which shews that no carbonic acid is present. On adding an excess of quicklime, no trace of ammonia is perceptible. And since no carbonic acid nor ammo- nia have been formed, water has been decomposed, con- sequently, no prussic acid is evolved. 31. The instant an oxide is poured into a solution of prussine in potash.a strong effervescence of carbonic acid is produced, and at the same time a strong smell of prus- sic acid.. Ammonia is likewise formed which remains combined with the acid employed, but when quicklime is- added, it is made sensible. Since, therefore, we are obliged to add an acid in order to form a prussian blue, it is evident the prussine is not decomposed when added to potash. 32. Soda, barytes and strontites produce the same ef- fect as potash. Hence we may conclude that prussine forms particular combinations with the alkalies, which 292 INTRODUCTION are permanent, till some circumstance determines the formation of new products. 33. These combinations are true salts, which may be regarded analogous to those formed with acids. In fact} prussine possesses acid characters. It ccntains two elc-. ments of azote and carbon, the first of which, according to M. Gay Lussac, is strongly acidifying. Prussine reddens the tincture of litmus, and metalizes the bases. When it unites with hydrogen it acts as a simple body, and produ- ces an acid. 31. The metallic oxides do not seem capable of pro- ducing the same effect on prussine as the alkalies. M. Gay Lussac having precipitated proto sulphate of iron by an alkali, so that no free alkali remained, caused the ox- ide of iron while moist, to absorb prussine, and then ad- ded muriatic acid. But he did not obtain the slightest trace of prussian blue,though the same oxide to which l.e had added a little potash before adding the acid, produced it in abundance. 35. From the above experiment we are led to con- clude that the oxida of iron does not combine with prus- sine ; water impregnated with this gas never produces prussian blue with solutions of iron, unless we previously add an alkali. 36. The peroxides of manganese and mercury, and the deutoxide of lead absorb prussine but slowly, hut when water is added, the combination is much more rap- id. With the peroxide of mercury, a greyish white com- pound is formed, a little soluble in water. 37. Prussine rapidly decomposes the carbonates at a dull red heat, and prussides of the oxides are ob- tained. 38. When prussine is passed through the sulphuret cf barytes, it combines without disengaging the sulphur, TO CHEMISTRY. 293 assume-? a brownish black colour an.l is very fusible. When thrown into water, a colourless solution is obtain- ed which gives a greenish brown colour to muriate cf iron. That which remains insoluble contains considera- ble sulphate which is probably formed daring the prepara- tion ofthe sulphuret of baryies. 39. When prussine is dissolved in the hydroguretted sulphuret of barytes, sulphur is precipitated, which is again dissolved, it becomes-saturated with prussine and a liquid is obtained having a very deep brown colour. 40. Prussine and sulphuretted hydrogen combine slowly with each other. A yellow substance crystallized in fine naedles is obtained, which is soluble in water, does not precipitate nitrate of lead, but produces prussian blue. 41. Whenever ammoniacal gas and prussine come in contact, they act upon each other ; but some time elap- ses before the effect is complete. White thick vapours are at first disengaged, which soon, disappear. The di- minution of volume is considerable, and the glass, in which the mixture is made, becomes opaque, its inside being covered with a solid brown matter. Exp. On mixing 90 parts of prussine with 227 of ammonia, they will combine nearly in the proportion of 1 to 1-J-. If thrown into water, it- dissolves only in very small pro- portions and gives a dark brown colour to the liquid, which produces no prussian blue with the salts of iron. 42. When prussic acid is exposed to the action of a voltaic battery, with 20 pair of plat--, much hydrogen gas is disengaged at the negative pole, while nothing ap- pears at the positive. This is because prussine is evolv- ed at that pole which remains dissolved in the acid 25* 294 INTRODUCTION 43. When an animal matter is calcined with pottsh or its carbonate, a prusside of potash is formed. It has been proved that potash separates, by the assistance of heat, the hydrogen of the prussic or hydrocyanic acid. We cannot then suppose that the acid is formed while a mixture of potash and animal matters is exposed to a high temperature. But we obtain a prusside of potash, and not of potassium. For potassium, when dissolved in water, gives only prussiate of potash, which is decom- posed b}r the acids, without producing ammonia and car- tonic acid ; while the prusside of potash dissolves in wa- ter without being altered, and does not give ammonia, carbonic acid, and prussic acid vapour, unless an acid be added. Observation. The above characteristics distinguish a prusside of a metal from a metallic oxide. 44. By heating prusside of mercury in muriatic acid gas, Sir H. Davy obtained pure liquid prussic acid and corrosive sublimate. By heating iodine, sulphur and phosphorus in contact with prusside of mercury, com- pounds of these bodies with prussine may be formed. 45. The compound of prussine and iodine is volatile at a very moderate heat, and on cooling collects in lioc- culi, adhering together like oxide of zinc formed by com- bustion. It has a pungent smell, and very acrid taste. PRACTICAL QUESTIONS. What is prussine ? Why has the term cyanogen been relinquished, and that of prus-hnc adopted ? How is prussine obtained ? How do you procure the pruis.'de of mercury ? What is the eil'cct when the cyanide is boiled with the red oxide of mercury ? TO CHEMISTRY. 295 When this compound is decomposed by heat, what is prodded ? What is the effect when the prusside is used with ex- cess ofthe peroxide ? What is necessary in order to prodnce pure prussine 1 What takes place when the neutral mercurial prusside is exposed to heat ? Is the gas, throughout the process pure ? Does any other metallic prusside give out prussine ? What are the properties of prussine ? Does heat decompose it ? How much does pure alcohol absorb ? What quantity does water absorb ? Do any other substances dissolve equally as much as water ? What effect does prussine have on tincture of litmus f What property does prussine possess which prussic acid docs not ? What effect has prussine on phosphorus, sulphur and iodine, when sublimed in it ? Do the metals combine with prussine ? Does potassium act on prussine ? What are the properties of prussine and potassium ? .. Is prussine inflammable ? .Suppose 100 parts of prussine be exploded, what takes place ? What may be inferred from this experiment ? What will the density ofthe radical be ? When a volume of hydrogen is added to a volume o* prussine, what is the result, and what do you infer? Who first established the analogy ? Relate the cxper.inent of M. Gay Lussac to determine the constituents of prussine. 296 INTRODUCTION Relate the other experiment ofthe same chemist, and the result. What does this experiment shew ? When a pure solution of potash is introduced into prus- sine, what is the effect ? How can you account for the production of prussian blue in the above process ? What other substances produce the sa.-.ie effect ? What do you infer from this ? Do the metallic oxides produce the same effect as al- kalies ? Does the oxide of iron combine with prussine ? What effect is produced by passing prussine through sulphuret of barytes ? What, when it is dissolved in the dydroguretted sul- phuret of barytes 1 Does prussine combine with sulphuretted hydrogen? Do ammonia and prussine have any effect on each other ? What follows, when prussic acid is exposed to the ac- tion of the voltaic battery ? What is formed when an animal matter is calcined with potash ? What is the argument on the subject ? How do you distinguish the prusside of a metal from a prusside of a metallic oxide 1 What facts have been discovered by Sir H. Davy ? What are the properties of prussine and iodine iucom- bination ? TO CHEMISTRY. CHAP. XXXII. Of the nature and composition of Vegetables. 1. Organized bodies are those which are furnished by nature with various parts, calculated to perform cer- tain functions connected with life, which bear the most striking and impressive marks of design, and are distin- guished bjr a vital principle, from which the various or- gans derive the power of exercising th^eir respective functions. 2. We know nothing of the principle of vitality but by its effects, nor by what means the organs are enabled to perform their functions either in the animal or vege- table departments. 3. The simplest class of organized bodies, is that of the vegetable world. These are distinguished from the mineral creation, not only by their more complicated nature, but by the power which they possess within themselves, of forming new chemical arrangements of their constituent parts by means of appropriate organs Though all vegetables are composed of carbon, hydro- gen and oxygen, with a few other occasional ingredients, they separate and combine these principles by their va- rious organs, in a variety of ways, and form with them different kinds of juices and solid parts, which exist ready made in vegetables, and may be considered as their immediate materials. 4. Potash, soda, lime, niagnrsia, silex, alumina, sul- phur, phosphorus, iron, manganese, and muriatic acic1, have been occasionally found in vegetables, but they oc- cur in very small quantities, and are scarcely more en- title J to be considered as belonging to them, than gold or 298 INTRODUCTION some other-substances, which are said to have been pro- cured from their decomposition. 5. There is no part of a plant which consists solely of one particular ingredient ; a certain number of vege- table materials must alwaj's be combined for the forma- tion of any particular part, and these combinations are carried on by sets of vessels, or minute organs, which select from other parts and bring together the several principles required for the developement and growth of those particular parts, which they are intended to form and maintain. It is probable these combinations are car- ried on by chemical principles ; for it would militate against all established theories, in chemistry, to suppose that the organs of plants could cause principles to com- bine which have no attraction for each other, nor can superior attraction yield to those of inferior power.— The organs of plants, probably, act mechanically by bringing into contact those principles in such propor- tions, as will, by their chemical combination, form the various vegetable products. 6. As long as a plant is in a growing state, the three principal constituents, carbon, hydrogen and oxygen, arc so nicely adjusted and connected together, that they are not susceptible of entering into other combinations, but no sooner does the principle of vitality cease, than this state of equilibrium is destroyed, a decomposition commences, and new combinations are formed, and an order of attraction succeeds, similar to what takes place in unorganized matter; and plants- eventually all return to their simple elements. 7. Li a chemical point of view there are two kinds of analysis, of which vegetables are susceptible. First, that which separates them into their immediate materi- als ; such as sap, resin, mucilage, &c. Secondly, that TO CHEMISTRY. 299 which decomposes them into their primitive elements, as carbon, hydrogen and oxygen. By the first analysis, wc obtain the following products from vegetables. 8. Sugar is obtained in the greatest abundance from the sugar cane. It is likewise procured from the sugar maple, beets, parsnips, carrots, and from the stalks of In- dian corn, zea maze. It crystallizes, is insoluble in wa- ter and alcohol. Taste sweet. Soluble in nitric acid, and yields oxalic acid. 9. Sarcoccl, a concrete juice brought from Arabia and Persia. It does not crystallize. Soluble in water and alcohol. Taste sweetish bitter. Soluble in nitric acid, and yields oxalic acid. 10. Asparagin, a substance obtained from asparagus. Crystallizes. Taste cooling and nauseous. Soluble in hot water ; insoluble in alcohol. Soluble in nitric acid, and convertible into bitter principle and tannin. 11. Gum does not crystallize. Taste insipid. Solu- ble in water, and forms mucilage. Insoluble in alcohol. Precipitated hy-silicated potash. Soluble in nitric acid, and forms mucous and oxalic acid 12. Ulmvn, a substance obtained from the elm. It does not crystallize. Taste insipid. Soluble in water, and does not form mucilage. Precipitated by nitric and oxymuriatic acids in the state of resin. Insoluble in al- cohol. 13. Inulin is a substance obtained from elecampane It is a white powder. Soluble m boihng water ,• but precipitates unaltered after the solution cools InsoluMe in alcohol. Soluble in nitric acid, and yields oxalic acid. 11. Starch is obtained from grain, horse chesnuts^ burdock roots, fcc. It is a white powder. Insoluble in cold water. Taste insipid. Soluble in hot water; opaque 300 INTRODUCTION and glutinous. Precipitated by an infusion of galls. Pre- cipitate redissolved in a heat of 120° F. Insoluble in al- cohol. With nitric acid yields oxalic acid and a waxy substance. 15, Indigo is a substance obtained from a plant grow- ing in various parts of the world, called indigofera tinc- toria. It is a blue powder. Taste insipid. Insoluble in water, alcohol and ether. Soluble in sulphuric acid.— Soluble in nitric acid, and converted into bitter principle and artificial tannin, 16. Gluten is a substance resembling gelatine, princi- pally found in the flour of wheat. It forms a ductile elastic mass with water. Partially soluble in water ; precipitated by infusion of nutgalls and chlorine. Solu- ble in acetic and muriatic acid. Insoluble in alcohol.— By fermentation becomes viscid and adhesive, and then assumes the properties of cheese. Soluble in nitric acid, and yiehls DXalic acid. 17. Albumen is a substance found in the green fecula5 ■of some plants, particularly those of the cruciform order. It is soluble in cold water. Coagulated by heat, and be- comes insoluble in hot water. Insoluble in alcohol. Pre- cipitated by infusion of nutgalls. Soluble in nitric acid. Soon putrifies. 18. Fibrin is a peculiar substance, found in vegeta- bles and animals. It is tasteless. Insoluble in water and alcohol. Soluble in diluted alkalies, ami in nitric acid. Soon putrifies, 19. Bitttr principle. Colour yellow or brown. Taste bitter. Equally soluble in water and alcohol. Soluble in nitric acid. Precipitated by nitrate of silver. 20. Extractive matier. Soluble in water and alcohol. Insoluble in ether. Precipitated by chlorine, muriate of TO CHEMISTRY. 301 ■tin, and muriate of alumina ; but not by gelatin. Dyes fawn colour. 21. Tannin. Taste astringent. Soluble in water and alcohol of specific gravity 0.810. Precipitated by gela- tin, muriate of alumina, and muriate of tin. 22. Fixed oils. No smell. Insoluble in water and alcohol. Form soaps with alkalies. Coagulated by earthy and metallic salts. Do not boil in a less tempera- ture than 600° F. 23. Wax. Insoluble in water. Soluble in alcohol^ ether and oils. Forms soaps with alkalies. Fusible. 24. Volatile oils. Strong aromatic smell. Insoluble in water. Soluble in alcohol. Liquid. Volatile. Oily. By nitric acid inflamed, and converted into a resinous "substance. 25. Camphor. Strong odour. Crystallizes. Very little soluble in water. Soluble in alcohol, oils and acids. Insoluble in alkalies. Burns with a clear flame, and vol* atilizes before melting. 26. Birdlime. Viscid. Taste insipid. Insoluble in water. Partially soluble in alcohol. Very soluble in ether. Solution green. 27. Resins. Solid. Melt when heated. Insoluble in water. Soluble in alcohol, ether and alkalies. Soluble in acetic acid. By nitric acid converted into artificial tannin. 28. Guaiacum, possesses the character of resins; but dissolve in nitric acid, and yields oxalic acid, but no tannin. 29. Balsams, possess the characters of the resins, but have a strong smell $ when heated, benzoic acid sublimes. It sublimes also when they are dissolved in sulphuric acid. They are converted by nitric acid into artificial tannin. 26 302 INTRODUCTION 30. Caoutchouc, or India rubber. Very elastic. Inso- luble in water or alcohol. When steeped in ether re- duced to a pulp, which adheres to any substance in con- tact. Fusible. Very combustible. 31. Gum resins, form milky solutions with water, transparent with alcohol. Soluble in alkalies. With ni- tric acid converted into tannin. Strong smell. Brittle. Opake. Infusible. 32. Cotton, composed of fibres. Tasteless. Very combustible. Insoluble in water, alcohol and ether. So- luble in alkalies Yields oxalic acid with nitric acid. 33. Suber, or cork, burns bright, and swells. Con- verted by nitric acid into suberic acid and wax. Par- tially soluble in water and alcohol. 34. Wood, composed of fibres. Tasteless. Insoluble in water and alcohol. Soluble in a weak alkaline lixivi- um. Precipitated by acids. Leaves much charcoal when distilled in a red heat. Soluble in nitric acid, and yields oxalic acid. 35. Emelin is a substance obtained from Ipecacuanha. It has no smell. Taste bitter and acrid. Soluble both in water and alcohol. Insoluble in ether. Not crystal- lizable. Precipitated by corrosive sublimate. Acts as a powerful emetic. 36. Fungin is the fleshy part of mushrooms. It seems to be a modification of woody fibre. 37. Hematin is the colouring principle of logwood.— Soluble in boiling water, and forms an orange red, which becomes yellow as it cools. Excess of alkali converts it first to purple, then to violet, and lastly to brown.— Unites with metallic oxides, forming a blue coloured compound. Precipitated by gelatin. Reddens by per- oxide of tin and acids. TO CHEMISTRY. 303 38. Nicotin is obtained from tobacco. Colourless. Has the taste and smell of the plant. Soluble both in water and alcohol. Volatile. Poisonous. Precipitated from its solution by tincture of galls. 39. Pollenin is a substance obtained from the pollen of flowers. It is yellow. Destitute of taste and smell. Insoluble in water, alcohol, ether, fat and volatile oils, and petroleum. Burns with flame. Soon becomes pu- trid on exposure to the air. The following substances are considered as new vege- table alkalies. 1. Aconita is a poisonous principle, extracted from the Aconitum napellum, or Wolfsbane. 2. Atropia is an alkaline principle, extracted from Atropa Belladona, or deadly night-shade. It is white, brilliant, crystallizes in long needles. Tasteless. But little soluble in water or alcohol. Resists a moderate heat. With acids, forms a neutral salt, and is capable of neutralizing a considerable portion of acid. 3. Brucia, or brucine is a substance extracted from the false angustura, or Brucea anti dysenterica. Soluble in 500 times its weight of boiling water, and in 860 of cold water. Taste exceedingly bitter, acrid and dura- ble in the mouth. Permanent in the air. Unites with the acids, and forms salts. 4. Cicuta is a vegetable alkali, obtained from hem- lock. 5. Datura is another alkaline substance, obtained from the Datura stramonium. 6. Delphinia is an alkaline substance, obtained from stavesacre, or Delphinium staphy sagria. Taste bitter and acrid. When heated, melts, and on cooling becomes hard and brittle, like resin. Soluble sparingly in water. 304 INTRODUCTION Soluble in alcohol and ether. Forms soluble neutral s.dts with acids. 7. Hyosciama is an alkali, obtained from Hyosciamus- nigra, or henbane. Crystallizes in long prisms. Soluble in sulphuric or nitric acid, and forms characteristic salts. Vapour prejudicial to the eyes. Very poisonous. 8. Morphia is an alkali,, extracted from opium, of which it constitutes the narcotic principle. Soluble in- 82 times its weight of boiling water, in 36 times its- weight of boiling alcohol, and in 42 times its weight of cold alcohol. Changes the infusion of brazil wood to & violet, and the tincture of rhubarb to a brown. It is so- luble in the acids, and forms salts. 9. Picrotoxia is the bitter and poisonous, principle of cocculus indicus, obtained in four sided crystals, of a white colour. Taste intensely bitter. Soluble in water, alco- hol and sulphuric ether. Unites with the acids, and, forms salts. It acts as an intoxicating poison. 10. Strychnia is a substance from strycknos nux vomica. Crystallizes in very small four sided prisms, terminated by four sided low pyramids. Colour white. Taste bit-. ter. Destitute of smell ; is not altered by exposure to the air. Neither fusible nor volatile, previous to de-. composition. When taken into the stomach, it .acts with. great energy. 11. Verutria is an alkali, obtained from veratrum sa- batilla, or ccvadilla, veratrum album, or white hellebore, and colchicum autumnale, or meadow saffron. White. Pulverulent. Destitute of odour. Excites violent sneez- ing. Very acrid, but not bitter. Scarcely soluble in cold water. TO CHEMISTRY. 30:"> PRACTICAL QUESTIONS. What are organized bodies ? Do we know any thing of the principle of vitality ? What is the simplest class of organized bodies ? How are these distinguished ? What substances have been found in vegetables ? Does any part of a plant consist of one particular in- gredient ? Why do not carbon, hydrogen and oxygen enter into other combinations while the plant lives 1 How many kinds of analysis of plant* are there 1 What are the properties of sugar? Of Sarcocol ? Of Asparagin ? Of Gum ? Of Ulmin ? Of Inulin ? Of Starch ? Of Indigo ? Of Gluten? Of Albumen ? Of Fibrin ? Of Bitter principle 1 Of Extractive matter'.' Of Tannin ? Of fixed oils ? Of Wax ? Of volatile oils ? Of Camphor? Of Birllime ? Of Resin ? Of Gu t.acum? Of Psl ;:ia ? * Of Caoutchouc ? 26-* 306 INTRODUCTION Of Gum Resin ? Of Cotton ? Of Suber ? Of Wood? Of Emetin ? Of Fungin T Of Hematin ? Of Nicotin ? Of Pollenin ? What are the new vegetables alkalies ? What are the properties of Aconita ? Of Atropia ? Of Brucia ? From what is Cicuta obtained ? From what is Datura obtained ? What are the properties of Delphinia ?' Of Hyosciama ? Of Morphia ? Of Picrotoxia ? Of Strychnia ? OfVeratria? CHAP. XXXIII. Of Colouring Matter—Decomposition of Vegetables—Fer- mentation. 1. The colouring part of vegetables is that used for dyeing, calico printing, and the like. 2. It is not found separate, but is combined with ex- tractive matter ; with gum, in which case, it is soluble in water. With farina, in this case, it is most soluble in TO CHEMISTRY. 307 sulphuric acid and with resins, when it requires alcohol, oil, or an alkali for solution. 3. Colouring matter has a great affinity for alumina and the oxides of tin; on which account, the solutions of these substances readily precipitate the infusion of col- ouring matter in water. 4. The modes of obtaining and transferring the col- ouring matter from one substance to another, so that it shall be fixed, constitute the art of dyeing. 5. The great variety of colours observed in dyed substances are reduced to four simple ones, viz. blue, ob- tained from indigo ; the red, afforded by madder, archil, brazil wood, cochineal, and some other substances ; yel- low, obtained from quercitron bark, sumach, tumeric, &c. and the black, obtained from a combination of iron with gallic acid. 6. In dyeing, some colours are permanently attached to the fabric by merely boiling or dipping it in them, while others leave a mere stain, not permanent 7. These are to be fixed through the medium of a proper basis. The principal bases are alumina, and some of the metallic oxides in combination with several acids. 8. Colours not permanent, are called adjective col- ours ; and those which are permanent, substantive. Exp. Take a little of the solution of indigo in sul- phuric acid, and add to it an equal quantity of carbonate of potash. Dip into it a piece of white cloth, it will become of a fine blue. Yellow cloth dipped into it will be changed to green, and red will be converted to a fine purple. 9. Cochineal is naturally of a red colour, but it is us- ed for scarlet dyeing ; to obtain the scarlet hue, a tar- trate of potash is used as a base, and the basis by which 303 INTRODUCTION it is fixed to the cloth is oxide of tin. It is an adjective colour. Exp. 1. Put a piece of white cloth into a decoction of cochineal, it will be simply stained. But add to it some tartrate of potash, and a little nitro muriate of tin, and it will afford a permanent scarlet colour. Exp. 2. The decoction of q uercitron bark is an ad- jective colour ; but by the aid of alumina as a base, we get a bright yellow. With the oxide of tin, all the shades from a pale lemon to a deep orange are formed ; and with the oxide of iron it gives a drab colour. Exp. 3. To a solution of carbonate of potash, add an equal quantity by weight of nitrate of iron. This will produce the permanent buff colour of the calico printer. Exp. 4. Equal parts of arnatto and potash of com- merce, will give the nankeen dye. Exp. 5. Take a piece of dark brown cloth, which has been dyed with fustic, and with a camel's hair pencil draw some figures on it with a solution of muriate of tin, the figures will quickly appear yellow, instead of brown. 10. To dye any kind of stuff, it should first be clear- ed of all glutinous and greasy matters, by being washed. In some cases, it is to be whitened ; it is then to be dip- ped into a mordant, which is an intermediate substance, that has a greater affinity for the colouring matter than the cloth has, such as the muriate of tin, sulphate of alumina, &.C. and then it is to be passed through the col- ouring liquid. 11. Mordants are employed to give lustre, as well as durability to the colour. They must be so-contrived as to have an affinity both for the colouring matter and the stuff itself. By a decomposition both ofthe mordant and the substance which holds the colouring matter in solu- TO CHEMISTRY. 309' tion, the colour is precipitated on the base of the mor- dant, and adheres to it. 12. Decomposition of vegetables takes place after the death of the plant. When vegetables cease to be pro- ductive, they cease to live,and decomposition immediately ensues, which eventually resolves them into their constitu- ents, hydrogen, carbon and oxygen. This process is slow- ly and gradually performed, during which time, a variety of new combinations are successively established and de-- stroyed; but in each of these changes the ingredients of vegetable matter,tend to unite in a more simple order of compounds, till they are ultimately brought to their ele-- mentary state, or, at least to their most simple order of combinations.. Thus vegetables are finally reduced to- water and carbonic acid, the hydrogen unites with one portion of the oxygen to form water, while the carbon combines with another portion to form carbonic acid. 13. Vegetables are susceptible of undergoing certain changes previously to the state of putrefaction, which is the last term of decomposition. The vegetable decom-. position is always attended by a violent, internal motion? occasioned-by the disengagement of one order of parti-. cles, and the combination of another. This is called fer-. mentation. There are several periods at which this pro-. cess stops, so that a state of rest appears to be restored and a new order of compounds fairly established. Means. must be used to secure these new combinations in their active state, or their-duration will.be transient ; and a new fermentation will take place, by which the compound last formed will be destroyed, and another and less com-. plex order will succeed. 11. Fermentation appears to be only the successive* steps by which a vegetable descends to iU final dissolu= tion. 310 INTRODUCTION 15. There are several circumstances required toprc*- duce fermentation. Water and a certain degree of heat are both essential to this process, in order to weaken the force of cohesion ofthe particles and cause them to sep- arate, that the new chemical affinities may be brought into action. 16. The several fermentations derive their names from their principal products, as the saccliarine, the vinous, the acetous, and putrefactive. 17. The saccharine fermentation is not confined to the decomposition of vegetables, as it commonly takes place in plants in a living state. 18. Sugar is not secreted from sap in the same man- ner as fecula, mucilage, oil and other ingredients of vege- tables, but it is formed rather from these materials than the sap itself, and it is developed at particular periods, a6 fruits, which do not become sweet until ripe, sometimes even after they have been gathered. Hence it appears that life is not essential to the formation of sugar, but pro- ceeds from the destruction ofthe previous order of com- binations, which must depend upon fermentation, while mucilage, fecula and other vegetable materials are secret- ed from sap by appropriate organs, consequently^ depend upon the vital principle. 19. The ripening of fruits is their first step towards decomposition as well as their last towards perfec- tion. 20. A change analogous to the saccharine fermenta- tion takes place during the cooking of certain vegetables, as parsnips, carrots, &c. in which sweetness appears to be developed during heat and moisture. The same process also takes plate in seeds previously to their sprouting. The materials ofthe seed must be decomposed, and the seed disorganised before a plant can sprout from it. TO CHEMISTRY. 31 J 21. Seeds contain fecula, oil and a little mucilage ; these substances are destined for the sustenance of the future plant, it is necessary that they undergo some change before they become fit for this function. The seeds when buried in the earth with a certain degree of moisture and temperature absorb water, which dilates them, separates their particles, and commences a new or- der of attractions, the product of which is sugar. The ■substance of the seed is thus softened, sweetened and con- verted into a milky pulp, appropriated to the nourish- ment ofthe embryo plant. 22. The saccharine fermentation of seeds is produced forthe purpose of malting. Exp. A quantity of barley is soaked in water for two or three days, the water being afterwards drained off', the grain heats spontaneously, andsometmes artifical heat is employed ; it swells, bursts, sweetens, shews a disposi- tion to germinate, and actually sprouts sometimes, to the length of an inch in one night. The process is then stop- ped by putting it into a kiln, where it is dried by a gentle heat. In this state it constitutes the substance called malt. 23. The saccharine fermentation takes place like- wise in hay, in stacks, and sugar is the product ; on this principle it is that old hay is more nourishing for cattle than new. 24. The second kind of fermentation is the vinous, s« called from wine being its product. 25. The saccharine fermentation appears to be favorable if not absolutely necessary to the vinous fermentation, so that if sugar be not developed during the life ofthe plant, the saccharine fermentation must be artificially produced before the vinous can take place. This is the case with barley, which does not yield any sugar until it is made olL INTRODUCTION into malt; and it is in that state only, that it is suscepti- ble of undergoing the vinous fermentation by which it is xonverted into beer. 26. The consequence of the vinous fermentation is the decomposition of the saccharine matter, and the for- mation of a spirituous liquor from the constituents ofthe sugar. 27. In order to promote this fermentation, not only water and a certain degree of heat are necessary, but also some other vegetable ingredients besides sugar,as fecula, mucilage, acids, salts, extractive matter, &c. all of which seem to contribute to this process, and give to the liquor its peculiar taste. Illustration. On this principle it is that wine is not ob" •tained from the fermentation of pure sugar; but fruits are chosen for that purpose, as they contain the vegeta- ble ingredients which promote the vinous fermentation and give its peculiar flavour. 28. *It is the proportion in which sugar is mixed with other vegetable ingredients that influences the produc- tion and qualities of wine. Observation. It is found that the juice of the grape not only yields (he greatest proportion -of wine, but of the most grateful flavour. 29. The following changes happen during the vinous fermentation. The sugar is decomposed and its constituents are re* combined -into two new substances ; the one a peculiar liquid substance called ulcohol, or spirits of wine, which Temains in the fluid;the other, carbonic acid gas,which escapes during the fermentation. Alcohol, therefore ap- pears to constitute the essential part of wine. And the varieties of strength and flavour of different kinds of wine ■are to be attributed to the different qualities of fruits TO CHEMISTRY. 313 from which they are obtained, independently of the sugar. 30. The principal difference between alcohol and sug- ar consists in this. Sugar is composed of carbon, hydro- gen and oxygen; during the formation of alcohol, carbon. ic acid is extracted from this, consequently alcohol con- tains less carbon and oxygen than sugar does, of course hydrogen is the prevailing principle ; which accounts for the lightness and combustible property of alcohol, and of spirits in general, all of which consist of alcohol various- ly modified 31. At the commencement of the vinous fermentatioa heat is evolved, and the liquor swells considerably, in consequence of the formation of carbonic acid. If the fermentation be checked by putting the liqour into casks before the whole of the carbonic acid is evolved, the wine is brisk, like champagne,from the carbonic acid, vulgarly called fixed air, its taste is sweet, from the sugar not be- ing completely decomposed. 32. During the decomposition and recomposition at- tending fermentation, a quantity of caloric may be disen- gaged, sufficient both to develope the gas, and to effect an increase of temperature; when the formation is com- pleted, the liquor cools and subsides, the effervescence ceases, and the thick, sweet, sticky juice of the fruit is converted into a clear, transparent, spirituous liquor, cal- led wine. 33. When wine of any kind is submitted to distillation, it is found to contain brandy, water, tartar, extractive col- ouring matter, and some vegetable acid. 34. Brandy is a mixture of alcohol and water, the al- cohol may be separated by re-distilling the brandy. 35. Brandy in its pure state is colourless, but in com- merce it is of a reddish yellow tint, sometimes made so 27 3J4 INTRODUCTION by art. and at otherjimes it extracts a colouring matter from the casks. It is usually coloured with a little burnt sugar. Brandy may be obtained from malt in a state o1" fermentation. 36. Rum is distilled from the juice of the sugar cane which contains so great a quantity-of sugar that it yields more alcohol than almost any other vegetable. Molasses which is extracted.from the bruised cane by means of water, after it has been pressed for making sugar, is for" mented and submitted to distillation, the product of which is rum. 37. Arrack is the product of the distillation of fermen- ted rice 38. Gin and whiskey are extracted from fermented graiD. The peculiar flavour of gin is owing to juniper berries, which are distilled with the grain. Whiskey is likewise obtained from potatos in a state of fermenta- tion. 39. The lees of wine consist of tartrate Of potash and extractive matter; tartar exists in the juice ofthe grape and many other vegetables, and is developed only by the vinous fermentation ; during which it is precipitated, and deposits itself on the internal surface ofthe cask. When purified from foreign ingredients it is called cream of tar- tar, which is much used in medicine and the arls. PRACTICAL QUESTIONS. What is the colouring part of vegetables ? How is it found ? Has it any affinity for other substances ? What constitutes the art of dyeing? I low many simple vegetable colours are there? Ars colours permanently attached to the fabric indve- ing ? TO CHEMISTRY. 315 How are colours to be fixed on the stuffs ? What are adjective and substantive colours ? For what is cochineal used ? What is the process of dyeing any kind of stuff? What is the use of mordants? When does decomposition take place in vegeta- bles ? Do vegetables undergo any change previously to the state of putrefaction ? What is fermentation ? What is requisite for fermentation ? What are the several fermentations ? Is the the saccharine fermentation confined to the de- composition of vegetables V Is sugar secreted from sap ? What is the first step towards decomposition ? How are seeds appropriated to the nourishment ofthe embryo plant? What is malting ? Does saccharine fermentation take place in hay ? What is the second kind of fermentation ? What appears necessary to the vinous fermenta tion? What is the consequence of the vinous fermenta- tion ? What is necessary to promote this fermentation ? What influences the production and.quality of wine ? What changes happen during the vinous fermenta- tion? What is the difference between alcohol and sugar ? What phenomena takes place during fermenta- tion ? Why is heat evolved during this operation ? What is wine found to contain ? 31$ INTRODUCTION What is brandy ? Whence is the yellow tint of brandy obtained ? Whence is rum obtained ? What is arrack ? From what are gin and whiskey obtained ? Of what do the lees of wine consist? What is tartar when purified? CHAP. XXXIV. Continuation of Fermentation. 1. In order to obtain alcohol perfectly free from wa- ter, it is necessary that it be rectified several times ; after which some muriate of lime should be added, in order to absorb any water that may remain. This should be ad- ded until it ceases to be moistened, inconsequence ofthe absorption of water. After which it should be redistilled in a water bath. 2. As alcohol is much lighter than water, its specific gravity is adapted as the tesj of its purity. 3. The chemical properties of alcohol are important and numerous. It is one of the most powerful chemical agents, and is particularly useful in dissolving a variety of substances which are not soluble by water nor heat. It dissolves volatile oils, and forms what are called essen- ces. It dissolves copal and mastic, and forms varn- ishes. 4. Alcohol has a great tendency to combine with wa- ter, and this is so strong that when water is added to a TO CHEMISTRY. 317 solution ofguia in alcohol, the alcohol combines with the water and the gum is precipitated. Observation. On this principle it is that if water be ad- ded to tinctures and elixirs, they immediately become tur- bid; as when added to a solution of camphor. 5. The addition of water to alcohol produces heat and a diminution of bulk, which is supposed to be caused by a mechanical penetration of particles, by which latent heat is forced out. 6. Alcohol is extremely combustible ; and will burn at a moderate temperature. 7. Alcohol in combustion produces much flame but no smoke, which arises from its combustion being complete.. The great quantity of flame proceeds from the combus- tion of carburetted hydrogen. It will also burn in a lamp without a wick, it takes fire at so low a temperature that this assistance is not required to concentrate-the heat and volatiliize the fluid. The rapidity of the combustion of alcohol may be much increased by first volatilizing it, as is exhibited in the self acting blow pipe. 8. The products of the combustion of alcohol consist, in a great proportion, of water, and a small quantity of carbonic acid; there is no smoke, or fixed remains, what- ever. Illustration. The oxygen which the alcohol absorbs in buriiing, converts its hydrogen into water, and its carbon into carbonic acid gas, and in this way it is completely consumed. 9. Ii 100 parts of alcohol be burnt in a chimney, which communicates with the worm pipe of a distilling appara- tus, the product which is condensed will be found to be 136 j arts of water. 10. If one part of alcohol be mixed in a retort, with four of sulphuric acid, and exposed to a moderate heat, a 27* 318 INTRODUCTION ga« is produced which is called heavy carburetted or pcr-carburretted hydrogen, called also olefiant gas. Itn specific gravity is 0.978. 100 cubic inches weigh 28.80 grains. 11. It possesses all the mechanical properties of air. It is invisible and void of taste and smell, after being wash- ed. When passed through a porcelain tube, heated to a cherry red, it lets fall a portion of charcoal, and nearly doubles its volume. At a higher temperature it deposits more charcoal, and augments in bulk. At the greatest heat to which we can expose it, it lets fall almost the whole of its carbon,and assumes a volume 3~ times great- er than it had at first. These remarkable results have led to the conclusion that hydrogen and carbon combine in many successive proportions. 12. The transmission of a series of electric sparks through olefiant gas, produces a similar effect with that of simple heat. 13. Olefiant gas burns with a splendid white flame When mixed with three times its bulk of oxygen, and kindled by a taper or electric spark, it explodes with great violence, and four volumes are converted into two volumes of carbonic acid. 14. Ether is a substance obtained from a!cohol,of which it forms the lightest and most volatile part. In order to obtain it, the alcchol must be decomposed; a certain pro- portion of carbon must be extracted, which is effected by the action of some acid on the alcohol. The acid and carbon remain nt the bottom of the vessel, whilst the decarbonized alcohol flies offin the form of a condensible vapour, called ether. That which is most- ly used is oL'Ldiaed by the action of sulphuiic arid on al- cohol. TO CHEMISTRY. 319 Exp. When strong sulphuric acid is poured on an equal weight of alcohol, the fluids unite with a hissing noise, and the production of heat, at the same time that a fragrant vegetable smell is perceived, in some measure resembling that of apples, which is ether. 15. Sulphuric ether is a very fragrant, light and vol- atile fluid. Its evaporation produces extreme cold. It is highly inflammable, and burns with a more luminous flame than alcohol. It freezes at — 46° F. It dissolves essential oils, resins, camphor and caoutchouc readily.— It boils in the atmosphere at 98° F. and in vacuo at — 20°. The density of its vapour is 2.586, that of air being 1. Ether admitted to any gas standing over mercury, doubles its bulk at atmospheric temperatures. If oxygen be thus expanded with ether, and then mixed with three times its bulk of pure oxygen, it explodes on being kind- led, forming carbonic acid and water. By detonating such a mixture, M. de Saussure has inferred ether to consist of Hydrogen 14.40 Carbon 67.98 Oxygen 17.62 100.00 These proportions per cent, correspond to Olefiant gas 80.05 Water 19.95 100.00 16. By passing ether through an ignited porcelain tube, it is resolved into olefiant gas, a viscid volatile oil, a little concrete oil, charcoal and water. 17. Ten parts of water combine with one of ether. 330 INTRODUCTION 18. Sulphuric acid converts ether into sweet oil of •wine. 19. If a very little ether be thrown into a large bot- tle containing chlorine, a white vapour soon rises, fol- lowed by explosions and flame. Charcoal is deposited and carbonic acid is formed. 20. If a few drops of ether be poured into a wine glass, and a fine platina wire be coiled and heated al- most to redness, then held suspended in the glass, close to the surface of the ether, the wire soon becomes in- tensely red hot, and remains so until the ether be ex- hausted. On this principle is constructed the Aphlogistic lamp, or lamp without flame. Illustration. This is owing to a very peculiar proper* ty ofthe vapour of ether, and many other combustible gaseous bodies. At a certain temperature, lower than that of ignition, these vapours undergo a slow and imper- fect combustion, in which light is not emitted in any sen- sible degree, yet a quantity.of caloric is extricated suf- ficient to react upon the wire and make it red hot; the wire in its turn keeps up the effect as long as the cmis sion of vapour continues. Observation. To perform the above experiment, pla- tina wire is absolutely necessary, because iron or steel being much belter conductors of heat than platina, the heat is carried off too fast by those metals to allow the accumulation of caloric necessary to produce the effect. 21. Alcohol is extensively used in pharmacy, chemis- try and the arts, and ether in medicine, though when taken in excess, it produces effects similar to those of in- toxication. 22. Acetous fermentation is so called, because it cc■: - verts wine into vinegar, by the formtrtion of acetous acid, which is the basis, or radical of vinegar. TO CHEMISTRY. 321 23. As the acidifying principle is oxygen, the contact ©f air is essential to this fermentation. In order to ob- tain pure acetous acid from vinegar, it must be distilled and rectified by certain processes. A good way is to ex* pose vinegar to a temperature of about 20° for one night, and after separating the ice, distil the liquor. 24. Vinegar may be obtained from wood; it was for- merly called pyroligneotts acid, but it is found when puri- fied to be common vinegar ; for this purpose it should be mixed with sulphuric acid, manganese, and common salt, and afterwards distilled over. 25. Whenever a vegetable substance turns sour, it. has ceased to live ; the acetous acid is developed by means ofthe acetous fermentation, in which the sub- stance advances a step towards, its final decomposition. 26. Any substance that haa undergone the acetous fermentation, will readily excite it in one that is suscep- tible of that process. Thus, if vinegar be added in small quantities to wine, that is intended to be acidified,, it will absorb oxygen more rapidly, and the process be com- pleted much sooner than if left to ferment spontaneously. Thus yeast, which is the product of the fermentation of beer, is used to excite and accelerate the fermentation of malt, which is to be converted into beer, as well as that of paste, which is to be made into bread. 27. Bread, by undergoing the acetous fermentation, acquires a certain savour which serves to correct the heavy insipidity of flour, and may be considered as the first stage of acidification ; if the process were carried further, the bread would become decidedly acid. Observation. Some chemists do not consider the fer- mentation of bread as the acetous, but suppose that it is a fermenting procoss peculiar to that substance, which= they have denominated panary fermentation. 322 INTRODUCTION 28. The putrid fermentation is the final operation^ oil nature. It is the last step towards reducing bodies to- their simplest combinations. 29.. To-effect this decomposition, a certain degree of moisture is necessary, and a sufficient degree of heat, together with access of air. For it is well known, that dead plants may be preserved by drying, or by the total exclusion of air for any length of time. 30. If we attend minutely to- the decomposition of plants from their death to their final dissolution, we shall generally find a sweetness developed in the seeds, and a spiritous flavor in the fruits, which have under- gone the saccharine fermentation, previously to the dis- organization and separation of the parts. Illustration. Apples, when over ripe, have a kind of spirituous taste, just before they become rotten. This is occasioned by the vinous- fermentation, which has suc- ceeded the saccharine, and if we follow up these chang- es attentively, we shall find the spirituous- taste followed by acidity, previously to the fruit passing to the state of putrefaction. Leaves which fall in autumn, do not im- mediately undergo a decomposition, but are first dried ; but when the rain sets in, fermentation commences, their gaseous products are evolved into the atmosphere, their fixed remains are mixed with the earths, they soon min- gle with the dust, and afford a pabulum for future plants. 31. The dry rot, which attacks beams of houses, may at first sight, be thought to be an objection to the above theory, because a current of air prevents it. But this must not be in su<;h proportion to the moisture as to dissolve the latter, and this is generally the case, when the rotting of wood is prevented or stopped by the free access of air. But dry rot, is not a true process of pu«- trefaction. It is supposed to depend on a peculiar kind TO'CHEMISTRY. 323 <" vegetation, which, by feeding on the wood, gradually destroys it. 32. The process of making compost manure, depends upon the putrid fermentation. Straw and other vegeta- ble matters undergo the putrid fermentation much more rapidly when mixed with animal substances ; much heat is evolved during this process, and a variety of volatile products are disengaged, as carbonic acid, hydrogen gas, and sulphuretted hydrogen. When all these gases have been evolved, the fixed products, consisting of carbon, salts, potash, &c. form a kind of vegetable earth, -which is composed of those elements which form the immedi- ate materials of plants, and is much more active than dung in its recent state. 33. Petrified vegetables, as they are called, are real- ly stone, consisting principally of silex. The process is this, when a vegetable substance is buried under water, or in wet earth, it is gradually decomposed. As each successive part of the vegetable is destroyed, its place is supplied by a particle of silicious earth, conveyed thither by the water. In process of time the vegetable is en- tirely destroyed, and its place supplied by the silex, hav- ing assumed its form and apparent texture, producing an appearance, as if the vegetable was turned to stone. Observation. It is impossible that either vegetables or animals should be turned to stone. They may be re- duced by decomposition to their constituent elements, but cannot be changed to elements that do not enterinto their composition. 34. When vegetables are buried in the sea, or in the earth, totally excluded from the air, they are subject to a peculiar change, by which they are converted into a new class of compounds, called bitumens. 324 INTRODUCTION 36. Bitumens are vegetables so far decomposed as to retain no organic appearance ; but their origin is easily detected by their oily nature, their combustibility, the products of their analysis, and the impression of the form of leaves, grains, fibres of wood, and even of animals, which are frequently exhibited in different specimens of *oal. 36. Bitumens are sometimes of an oily liquid consist- ence, as the substance called naphtha. But they are more frequently solid, as asphaltum and jet. 37. Naphtha is a light, thin, colourless oil, and highly •odoriferous. It is found on the surface of water in cer- tain springs in Italy, and on the shores of the Caspian Sea. It is about one quarter lighter than water. It is very inflammable, and burns with a penetrating smell, and much smoke. By long exposure to the air, it be- comes thick, and passes to the state of petroleum. It ap- pears to be composed of -carbon 82.2 and -+- hydrogen 14.8 38. Naphtha being destitute of oxygen, renders it the most proper liquid for preserving potassium ; because it has so great an affinity for oxygen, that it seizes it when- ever it comes in contact with it 39. Asphaltum is a smooth, hard, brittle, black or brown substance, which breaks with a polish, melts easi- ly when heated, and when pure, burns without leaving any ashes. It is found in different parts of the world, but in the greatest quantity on the shore of the Dead Sea. Observation. The Egyptians used asphaltum in em- balming the dead, under the name of mumia mineralis, for which it is well adapted. It was used for mortar st Babylon. TO CHEMISTRY o2b 40. Jet is harder than asphaltum, and susceptible of so high a polish, that it is used for many ornamental pur- poses. It is composed of Carbon 75 •Bitumen 22 Earth 2 Water 1 100 Its specific gravity is 1.3. 41. Petroleum is a bituminous substance, thicker than naptha, has a greasy feel, is wholly, or in part, trans- parent, and a little heavier than naptha. It is very high- ly inflammable, and has the property of combining with fat and essential oils, with resins, camphor and sulphur ; and when rectified, it dissolves caoutchouc. 42. Mineral tar is thicker and more viscid than pe- troleum, and of a reddish or blackish brown colour ; im its chemical properties, it resembles petroleum. 43. Mineral pitch is extremely inflammable, of a brownish or blackish colour; it is nearly twice as heavy as that of water. 44. Coal is a bituminous substance, which seems to be composed of mineral and animal substances. It ap- pears to consist principally of vegetable matter, mixed with the remains of marine animals and marine salts.— It occasionally contains a quantity of sulphuret of iron, commonly called pyrites. 45. Coke is a kind of fuel, artificially prepared from coals, hy means of charring or burning in close vessels, to expel the volatile parts. It is composed of carbon with some earthy or saline ingredients. 40. Amber is considered as a bitumen, called by the ancients, Electrum, whence the term electricity, because 28 326 INTRODUCTION it is peculiarly, and was once supposed to be exclusively electric. 47. It is found in mine* in some parts of Prussia, and sometimes floating on the sea. 48. It is a hard, brittle, tasteless substance, some- times perfectly transparent, but mostly semi-transparent or opaque, and of a glossy surface. It is , found of all colours, but chiefly yellow or orange. Its fpecific grav- ity is from 1.065 to 1.100. Its fracture is even, smooth and glossy. It is fusible at 550° F. It consists of an oil and an acid, the former is called oil of amber, the latter succinic acid. Observation. By some experiments made on the ef- fects of light on amber, Dr. Brewster has been led to conclude that it is an indurated vegetable juice. 49. Peat or turf, is composed of the remains of vege- t able organization, and consists in a great measure of the fibres of mosses, with the branches and roots of trees.— It is extremely inflammable in the open air, and when distilled in close vessels, yields products similar to those of coal. PRACTICAL QUESTIONS. How can pure alcohol be obtained ? What is adopted as the test of the purity of alcohoH What are the chemical properties of alcohol ? Has alcohol any affinity for water ? What is the effect of adding water to alcohol ? Is alcohol combustible ? What are the phenomena of the combustion of alco- hol ? What are the products of the combustion of alcohol ? How much water will 100 parts of alcohol produce by combustion ? TO CHEMISTRY. 327 How is olefiant gas formed ? What are its properties ? How can a similar effect, as that of simple heat, be produced on olefiant gas ? What appearances are produced in the combustion of olefiant gas ? What is ether ? What are the properties of sulphuric ether ? What is the effect of passing ether through an ignited porcelain tube ? How many parts of water combine with ether ? Into what does sulphuric add convert ether ? What is the effect of chlorine on ether? How do you perform the experiment which illustrates the principle of the aphlogistic lamp ? Why will not iron and steel answer ? 1$ alcohol much used?- What is the acetous fermentation ? What is necessary for this fermentation ? How do you obtain it pure ? Can viuegar be obtained from wood ? When is the acetous acid developed ? How can the acetous fermentation be excited ? What does bread acquire by the acetous fermentation? What is the putrid fermentation ? What is necessary to effect this decomposition ? What shall we generally find by attending minutely to the decomposition of plants ? How do you illustrate this ? Is not the dry rot an exception to this theory ? Upon what does the process of making compost de- pend ? What are petrified vegetables ? 328 INTRODUCTION What is the effect of burying vegetables in the sea, .01 at great depths in the earth ? What are bitumens ? Are they of different consistencies ? What is naptha ? Why is naptha best calculated for preserving pota^ sium ? What is asphaltum ? What is jet ? WhaJ is petroleum 1 What is mineral tar ? What is mineral pitch ? What is coal ? What is coke ? What is amber ? What is peat or turf t CHAP. XXXV. Of Vegetation. I. The most obvious difference between animals and vegetables is, that the former are in general capable of conveying themselves from place to place; whereas vegetables being fixed in the same place absorb by means of their roots and leaves, such support as is within their reach. This appears to be air and water. 2. The greatest part of the support of animals are the products formed in the vegetable department. The products of these two departments in the hands of the chemist, are remarkably different. TO CHEMISTRY. 329 3. One of the most distinctive characters appears to be the presence of nitrogen or azotic gas, which may be extricated from animal substances by nitric acid, and en- ters into the composition of ammonia, afforded by de- - Structive distillation. 4. It was long supposed that ammonia was exclusive-" ly confined to the animal department, but it is now found that certain plants afford it 5. The nutrition or supporrof plants appears to re- quire water, earth, light and air. Various experiments , have been instituted to shew that water is the only ali-- ment which the root draws from the earth. Illustration. Von Helmont planted a willow weighing fifty pounds, in a certain quantity of earth, covered with sheet lead It-was watered for five years with distilled water, and at the end of that time, the tree weighed 169 pounds, three ounces, and the earth in which it had veg- etated was found 'to have suffered a loss of only three ounces. Mr. Boyle repeated the same experiment upon a plant, which at the end of two years weighed fourteen pounds more, and the earth in which it-vegetated, lost no perceptible portion of its weight' By Duhamel and Bonnet supported plant? with moss, and fed them, with pure water.- The vegetation was of the most vigorous kind, and the flowers were more odo- riferous, and :he fruit of a better flavour «■ Mr. Tillet raised plants of the gramineous -kinds in the same man- ner, with this difference only, -his supports, were* of pounded glass, or qtuirtz ia powder. . 7.. Hales has observed, that a plant 'that weighed three pounds, gained three ounces after a heavy dew. 8. Hyacinths, and other bulbous and gramineous plants, are sometimes raised in saucers or bottles filled with water. 28* 330 INTRODUCTION 9. Braconet caused mustard seed to germinate, grow, and produce plants that came to maturity, flowered and ripened their seed in litharge,,flowers of sulphur, and very small unglazed shot. 10. All plants do not require the same quantity of water, and nature has varied the organs of the same in- sdividuals, agreeably to the necessity of their being .sup- plied with this food. 11. Plants which transpire little, such as the mosses and lichens, have no need of a great quantity of water ; accordingly,, they are placed on dry rocks, and have scarcely any roofs ; but plants which require a larger quantity, have roots which extend to a great distance, and absorb humidity throughout their whole surface. 12. The leaves of plants have likewise the property of absorbing water, and of extracting from the atmos- phere the same food which the root draws from the earth. Such are some species of aloes, and the cactif which will live and flourish in dry earth for a great length of time, and when much water is added to the earth, they soon sicken and die. 13. Plants which live in the water, receive the fluid at all their pores,and have but very little need of roots ; we find that the fucus, the -ulva, &c. have no roots. 14. The manure not only affords the alimentary principles, but likewise favours the growth of the plant, by that constant and steady heat, which its decomposition produces. 15. From the above circumstances it appears, that the influence ofthe earth in vegetation is almost totally confined to the conveyance of water, and probably, the elastic products, from the putrifying substances in the rlaut. TO CHEMISTRY. 331 16. Vegetables cannot live without air. From the experiments of Priestley, Ingenhousz and Sennebier, it is ascertained, that plants absorb the azotic part of the atmosphere ; and this principle appears to be the cause of the fertility which arises from the use of putrefying matter, in the form of manure. The carbonic acid is likewise absorbed by vegetables, when its quantity is email. But in large quantities it proves fatal. 17. According to Chaptal, the carbonic acid predom- inates in the fungus and other plants, when excluded from the light. But by causing these vegetables, to- gether with the body upon which they were fixed, to pass, by imperceptible gradations, from an almost abso- lute darkness, into the light, the acid very nearly disap- peared ; the vegetable fibres being proportionally in- creased, while the resin and colouring principles were developed, which he ascribes to the oxygen ofthe same acid. It has been observed, that when plants are water- ed with water, impregnated with carbonic acid gas, they transpired an extraordinary quantity of oxygen, which likewise indicates a decomposition of the acid. 18. Light appears to be essential to the growth of plants. In the dark, they grow pale, languish and die. Observation: The affection of plants for the light is manifest in such vegetation as is conducted in. an apart- ment of the house ; where the light is admitted on one side, the plants all turn in that direction. If the light proceed from two sides, they will turn to that which is- the strongest; and if the light proceed from above, they will grow upright. In a thick wood, where but very little light proceeds from any direction but perpendicu- larly, the trees are much taller, straighter, and have fewer and smaller branches than those which grow in the open field, which is owing to the same cause. 332 INTRODUCTION 19. Whether the matter of light be condensed into the substance of plants, or whether it act merely as a stimulus or agent, without which the other requisite chemical processes cannot be effected, is uncertain. 20. The processes in plants serve, like those in ani- mals, to produce a more equable temperature, which is for the most part above that of the atmosphere. Observation. Dr. Hunter observed by keeping a ther- mometer plunged in a hole made in a sound tree, that it constantly indicated a temperature several degrees above that of the atmosphere, when it was below the 56° of Farenheit; whereas the vegetable heat in hotter weath- er, was several degrees below that of the atmosphere.— The same philosopher has observed, that the sap, which out of the tree, would freeze at 32°, did not freeze in the tree, unless the temperature was as low as 17°. 21. The vegetable heat may increase or diminish by several causes, of the nature of disease ; and it is saic\ may become perceptible to the touch-in very cold weath- er. 22. Germination is the vital developement of a seed, when it first begins to grow. 23. In ordeT to understand the nature of germination, we must be acquainted with the different parts of which a seed is composed. 24. The seed is formed of an external covering, cal- led the parenchyma, which is to constitute its first nour- ishment; this imbibes nourishment from the earth, elab- orates it,'and does not transmit it to the inclosed germen, until it is reduced into proper nutriment. 25. The seed is divided into compartments, called lobes or'cotyledons,- as is observed distinctly in the garden- bean, which is a gcod- example for illustration.. Plate 5, fig. 1 and 2, A. or the dark coloured kind of string which ?LATB v. ft*?. /. Ftr/.z. F^-3 Ilo. 4 ft#7 TO CHEM1STRV. 33$ divides the lobes, is called the radicle, because it forms- the root of the plant. B. is the plumula which is enclos- ed within the lobes, and is that part from which the stem arises. At the thick end of the bean there is a. small hole visible to the naked eye as in fig. 2 A. imme- diately over the radicle,, in order to g\ve it a free pas- sage into the soil. The plumula and the radicle in col- our and consistency are much alike. Fig. 7, is a trans- verse section ofthe bean. 26. Within the radicle there is a substance called the seminal root, which divides into three branches ; the middle one runs directly up to the plumula ; the other two pass into the lobes on each side, and send forth smaller branches, till their ramifications become quite minute on the surface of the lobes, as in fig. 4. Fig. 5, is a transverse section of the radicle. Fig. 6, a trans- verse section ofthe plumula, shewing the organs or ves- sels of the seminal root. 27. When a seed is placed in a situation favorable to vegetation, it very soon changes its appearance. It im- bibes water, which softens and swells the lobes. It.then absorbs oxygen, which imbibes some of its carbon, and is returned in the form of carbonic acid. This loss of car- bon increases the comparative proportion of hydrogen and oxygen in the seed, and excites the saccharine fer- mentation, by which the parenchymatous matter is con- verted into a kind of sweet emulsion. In this form, it is conveyed into the radicle by vessels appropriated to that purpose ; and in the mean time, the cotyledons are rent asunder, the radicle strikes into the ground, and becomes the root ofthe future plant ; hence the fermented liquid is conveyed to the plumula whose vessels have been, previously distended by the heat of the fermentation.— The plumula being thus swelled, as it were, by the 334 INTRODUCTION emulsive fluid raises itself up to the surface ofthe caTth' bearing with it the cotyledons, which,, as soon as they come in contact with the air, spread themselves and are transformed into leaves, as in fig. 3. 28. As soon-as a plant derives nourishment from the- soil, it requrres leaves, which are the organs by which it throws off ^ts superabundant fluid. This transpired' fluid consists of a little more than water. The sap, by this process is converted into a fluid of a greater consis- tence, which i9 appropriated to its several parts.. 29. When the leaves of plants are destroyed by acci- dent,^ not only diminishes the transpiration^ but also the absorption by the roots.. The quantity of sap absorbed being always in proportion to the quantity of fluid thrown off by transpiration.. Hence it is necessary that a young plant should unfold its leaves as soon as it begins to derive nourishment from the earth. 30. Seeds will not germinate unless moisture be present. Water, therefore, appears to be essential to germination, tOO much however* i^-no less prejudical thanooBe at all. Water is the vehicle which carries into the plant, the- various salts and other ingredients required for the for- mation and support of the vegetable system. Part of the water itself is decomposed by the organs of the plant, the hydrogen becomes a constituent part of oil, of ex- tract, of colouring matter, &c. whilst a portion of the ox- ygen enters into the formation of mucilage, fecula, sugar and vegetable acids. But a greater part ofthe oxygen is converted into a gaseous state by the caloric disengaged from the hydrogen, during the condensation in the forma- tion of the vegetable materials. Id this state the oxygen is transpired by the leaves of the plant, when exposed to- the sun's rays. 31. Seeds will not germinate even though supplied TO CHEMISTRY. 335 with a suitable portion of moisture, unless they are placed in a proper degree of temperature. No seed of which we are acquainted,will vegetate in a temperature below 32° F. notwithstanding a degree of cold below zero, will not des- troy the germinating power, unless moisture be present, but there must be a certain point of temperature in order for germination; this varies with different seeds. Every plant seems to require -a 'degree of heat peculiar to itself, •at which point its seeds begin to germinate ; for we find that every seed of a plant which grows spontaneously has a peculiar season when it springs from the earth, and this season varies with the temperature of the climate. Thus seeds of the same plant, sown at the same time in •different countries, will germinate sooner in a warm than -a cold one. 32. Seeds although supplied with moisture and placed in a proper temperature will not germinate, provided atmospheric air be completely excluded from them. It k supposed to be owing to this circumstance, that seeds do not germinate when buried at great depths in the earth. Mr. Scheele, found that beans would not vegetate unless ox- ygen gas were present. No seed will germinate in pure ■nitrogen, or carbonic gas. Hence itapears that it is not the whole of the atmosphere, but the oxygen that causes the germination of seeds. 33. It has been ascertained that seeds germinate more rap.dly when steeped for a short time in chlorine. This substance is well known for the facility with which it de- composes water, and sets at liberty the'hydrogen. Observation. Chlorine seems to augment the vegeta- tive power of seeds. Those which could not be made to sprout even in green houses, have been found to ger- minate when steeped in chlorine. By this process Mr Humbolt succeeded in making the seeds of many plants 536 INTRODUCTION which he fdund in South America, to grow in Vienna, which not all the art of the gardeners was able,previously to effect. 30. Different opinions have been entertained with respect to light on seeds. From experiments, it appears injurious, in consequence of the heat which the rays of light Impart to seeds, for if proper care be taken to in- tercept the direct rays of the sun, seeds germinate as well in the light as the shade. 31. When a seed is placed in favorable situations, it gradually imbibes moisture, and very soon emits a quan- tity of carbonic acid gas, even though no oxygen be pres- ent in a separate state, but the process soon "terminates and no germination takes place, but if there be a suffi- cient supply of oxygen gas, a portion of it is converted into carbonic acid gas. 32. From experiments it appears that if seeds be left to germinate in a determinate portion of oxygen gas, the bulk is not altered, the carbonic acid gas being equal to the oxygen gas which has disappeared. Hence it is in- ferred that the carbonic gas, contains exactly the quanti- ty of oxygen gas consumed. 33. No oxygen gas is absorbed by the seed, at least if it be absorbed, none of it is retained, it being thrown off in combination with the carbon. 34. The quantity of oxygen thus changed into car- bonic acid by the germination of the seed, is in some measure proportional to the weight ofthe seed. Observation. From the experiment of M. De Saussure, it appears that wheat and barley, weight for weight, con- sume less oxygen than peas, while peas consume less than common beans and kidney beans. The oxygen consumed by wheat and barley amounted to 3^5 0I* their weight, while that of common beans and kidney beans, amount ed to ,-J-j of their weight. TO CHEMISTRY. 3o7 ■ >3. It is probable that a portion of water is formed by the union of its constituents, previously existing in the grain. 3G. In some plants the Cotyledons do not rise above the earth, but in that case they perform the same office as those which do, that is to prepare the nourishment for the sustenance of the young plant. 37. It does not apppear that there is any communication between the cotyledons and the plumula, the nourishment therefore must pass into the plumula, from the radicle, accordingly, we find that the plumula does not begin to vegetate until the radicle has made some progress. But -ince the plant has ceased to vegetate, if the cotyledons be removed before the plumula is developed, the radi- cle must be sufficient of itself to carry on the process of vegetation,and the cotyleJens are continued forthe pur- pose of performing a part, that is, they prepare the food which the root at first is unable to do. 38. When the cotyledons assume the form of leaves, the nourishment, which was originally deposited in them for the support of the embryo plant, is exhausted, but they still continue necessary. They must therefore re- ceive the nourishment which is imbibed by the root, pro- duce some change in it to render it suitable for the pur- poses of vegetation, and then send it back to be transmit- ted to the plumula. 39. When the plumula has just ascended from the ground, if the radicle leaves be cut off, the plant does not cease to vegetate, but it seems to be deficient in nour- ishment, and scarcely ever arrives at maturity. 40. When the plumula has arrived at a certain size, and completely expanded its leaves, the cotyledons may be removed without detriment to the plant, and they very soon decay of themselves. It appears then that the office 29 338 INTRODUCTION of the cotyledon is performed by that part which is above ground. 41. The bark is composed ofthe epidermis, the paren- chyma and the cortical laves. 42. The epidermis is the external covering of the plant. It is a thin transparent membrane, consisting of a number of slender fibres, crossing each other and form- ing a kind of network. When of a white glossy nature as in several species of trees, in the stems of rye and wheat and of seeds, it is composed of a thin coating of silicous earth, which is no doubt designed to protect those slender stems from in- jury. Illustration. Two rattan canes struck against each other in the dark emit sparks of fire. In evergreens the epidermis is mostly resinous, and in some plants, it is formed of wax. This from its want of affinity for water, tends to preserve the plant from the weather, to which these species of vegetables are peculiarly exposed. 43. The perenchyma is immediately beneath the epi- dermis, and is usually green. It is not confined to the stem or branches, but extends over every part of the plant; it forms the green matter of the leaves,, and is composed of tubes filled with a peculiar juice. 44. The cortical layers are immediately in contact with the wood. They abound with tannin and gallic acid, and consist of small vessels through which the sap descends after being elaborated in the leaves. These layers are renewed every year. 45. The sap ascends through the tubes of the albur- num or wood, which is immediately beneath the cortical Livers. TO CHEMISTRY. 339 ■i(J-. The wood is composed of woody fibres, mucilage and resin. The fibres are disposed of in two ways, some of them longitudinally, and these form what is called silver grain of the wood, as in fig. 8. The others, which are con- centric, are called, the spurious grain. These last are disposed in layers, from the number of which the age of the tree may be computed, a new one being produced every year, by the conversion of bark into wood. The oldest and most internal part of the alburnum is called heart wood, in this no vital functions are discovered. It is through the tubes of the white part of the wood that the sap rises. These spread into the leaves, and there communicate with the extremities of the vessels of. the cortical layers into which, they pour their con- tents. 47. The tubes of the parenchyma are supposed to perform the important office of secreting from the sap the peculiar juices from which the plant more immedi- ately derives its nourishment. These juices are very conspicuous, as the vessels which contain them are much larger than those through which the sap circu- lates. 48. The peculiar juices of plants differ much in their nature, not only in different species of vegetables, but frequently in different parts of the same individual plant. They are sometimes saccharine, as in the sugar cane, maple, &c. sometimes resinous, as in firs and evergreens, and sometimes of a milky appearance, as in the laurel. • 49. Vegetables possess a peculiar heat, analogous to animal heat, and is considerably above that of unorganiz- ed matter in winter, and below it in summer. The wood of a tree is about 60° when that of the atmosphere is 340 INTRODUCTION about 70" or 80*. And the bark is seldom below 40° in winter. 50. It is from the sap after it has been elaborated 1m the leaves, that vegetables derive their nourishment : in its progress through the plant from the leaves to the root, it deposits in several vessels with which it commu- nicates, the materials on which the growth and nourish- ment cf each plant depends. It is in this way that the various peculiar juices are formed, such as the saccha- rine, oily, mucous, acid and colouring; as also the more solid parts, fecula, woody fibre, tannin, resin, concrete salts. All the materials of vegetables, as well as the or- ganized parts of plants, which, besides the power of se- creting these from the sap for the general purpose ofthe plant, have also that of applying them to their own par- ticular nourishment. 51. The rca-on why plants vegetate at one season of the year more than at another, seems to be this. The warmth of spring dilates the vessels of plants and produ- ces a kind of vaccuum into which the sap, which had re- mained in a state of inaction in the trunk during winteri rises. This is followed by the ascent of the sap contain- ed in the roots, and room is thus made for fresh sap, which the roots in their turn pump up from the soil. This process goes on until the plant blossoms and bears fruit, which terminates its summer career; but when the cold weather sets in, the fibres and vessels contract, the bares wither, and can no longer perform their cffice of transpiration, and as this secretion stops, the roots rease to absorb snp from the soil. If the pkint be an annual, its life then terminates ; if not, it remains in a Ante of torpid inaction during the winter ; or the only internal motion which takes place, is that of a small quan- TO CHEMISTRi. 34 i tily of resinous juice, which slowly rises from the stem into the branches, and enlarges their buds during the winter. PRACTICAL QUESTIONS. What is the most obvious difference between animals and vegetables 1 From what does the greatest part of the support of animals arise ? What is one ofthe most disitinguishing "properties of animal substances ? Is ammonia exclusively confined to the animal depart- ment ? What does the nutrition of plants require ? Do all plants require the same quantity of water? What plants require the least water? What property do the leaves of plants possess 1 What plants have the least need of roots ?. What office does manure perform ? To whatjs the influence of earth confined in vegeta*- t.ion ? Can vegetables live without air? ' Is carbonic acid absorbed by vegetables ? " In what plants does the carbonic acid predom* inate •? Is light essential to the growth of plants ?' How does light act upon plants ? What do the processes in plants serve to produce ? How can the vegetable heat increase or dimin- ish ? ■ What is germination ? What is necessary in order to understand the nature of." germination ? 20* ;j!2 INTRODUCTION What is the external covering ofthe seeds? How is the seed divided ? What is found within the radicle? What takes place at the commencement of germina- tion ? What does a plant require when it derives nourish- ment from the soil ? What is the effect of destroying the leaves of a plant ? Is water essential to germination ? Is a proper degree of temperature necessary to ger- mination ? Is atmospheric air necessary ? Has chlorine any effect on the germination of seeds ? What effect has light on seeds ? What gas is emitted when se^ds are placed in a favour- able situation ? Is the bulk of oxygen gas altered by germination? Is any oxygen gas absorbed by the seeds ? What proportion does the oxygen that is changed into the carbonic gas bear ? Is any water formed ? Do the cotyledons in all cases rise above the earth ? How does the plant obtain its nourishment 1 Are the cotyledons necessary v. hen they assume the form of leaves ? What is the effect if the radicle leaves be ivny.v- ed when the plumula has just ascended from the ground ? Of what is the bark composed ? What is- the epidermis ? What is the parenchym i ? Where ere the certic;-.! laver? situated '! TO CHEMISTRY. 343 How does the sap ascend? Of what is the wood composed ? Do the peculiar juices of plants differ in their na- ture ? Do vegetables have a peculiar heat ? From what do vegtables derive their nourishment? Why do plants vegetate at one season of the year and not at another ? CHAP. XXXVI. Of the Animal Department. 1. The bodies that form the subjects of chemical re- search have all undergone a variety of combinations and decompositions previously to our commencing an exami- nation. This process in animal matter is called animal- ization. Which is performed on substances which enter as nourishment into the animal system. It is performed by peculiar organs, and is analogous in some measure to the chemical process in vegetables. 2. Animal as well as vegetable bodies, may be con- sidered as constituting a peculiar apparatus, for carrying on a determinate series of chemical operations. Vege- tables seem capable of operating with fluids only, and nearly at the temperature of the atmosphere. But most animals have a provision for mechanically dividing sol- ids by mastication; which performs the same office as grinding, pounding or levigating does in chemistry ; in this way the surfaces ara-enlarged to be acted upon by solvents, 3U INTRODUCTION 3. The process carried on in the stomach, sec ins to be analogous to that which we distinguish in chemi-try by the name of digestion. 4. The bowels, whatever other functions they may perform, evidently constitute an apparatus for filtering or conveying off the fluids ; while the more solid parts ofthe elements which are probably incapable of being converted into fluids, but by an alteration which would perhaps destroy the texture of the machine, are rejected as usels-se Organized beings are so contrived, that their exis- tence continues, and all their functions are performed as long as the vessels are supplied with materials, to occupy the place of such as are carried off by evaporation, from the surface or otherwise ; as long as no great change is made, either by violence or disease, in those vessels or the fluids they contain. But as soon as the process is de- ranged in any considerable degree, the arrangements are altered; the temperature in land animals is changed,the minute vessels are acted upon and destroyed, and this struck by new combinations and decompositions returns to the general mass of unorganized matter, with a rapidi- ty which is usually greater, the more complicated its con- struction. 5. Animal and vegetable substances approach each other by insensible gradations, so that there is scarcely any simple product in the one, which is not found in a greater or less quantity in the other. There is one prin- ciple however, which abounds in animals, which is rare- ly, and in very small quantities found in vegetables ; this is nitrogen. There exists likewise in animal substances a larger and more uniform proportion of phosphoric acid, and other saline matters. But these are not essential to animal matter. TO CHEMISTRY. 345 6. Animal substances afford ammonia by destructive distillation ; this does not exist in the substance ready formed, but appears to be produced by the combination of hydrogen anil nitrogen, during the changes produced either by fire or the putrefactive process. 7. The fundamental principles of animal compounds, appear to be carbon, hydrogen, oxygen and nitrogen.— Sulphur, phosphorus, lime, magnesia and soda, are occa- sionally combined with these. Metals are also found in very minute quantities in animals. 8. The analysis of animal substances are both difficult and imperfect ; for as they cannot be examined in their living state, and are liable to alteration immediately af- ter death, it is probable that when submitted to chemical investigation, they are always, more or less altered, in their combinations and properties, from what they were in a living state. 9. The following are peculiar chemical products of animal organization, viz. Gelatine, albumen, fibrin, ca- seous matter, colouring matter of the blood, mucus, urea, picromel, osmazome, sugar of milk, and sugar of diabetes. The compound animal products are the various solids and fluids, whether healthy or morbid, found in different animals, as a variety of acids, muscle, skin, bone, blood, urine, tearj, bils, morbid concretions, brain, gastric juice, &c. 10. Gelatine, or jelly is the chief ingredient of skin, and of all the membranous parts of animals. It may be obtained from these substances by means of boiling wa- ter, unler the forms of glue, size, isinglass, and transpar- ent jelly. 11. It is soluble in water, and is capable of assuming a well known elastic, and tremulous substance by cool- ing, when the water is not too abundant, and liquifiable 316 i:\TRODUCTKW again on increasing its temperature. This last property distinguishes it from albumen, which becomes consistent by heat. It is precipitated in an insoluble form by tan- nin, and it is this action of tannin on gelatine that is the art of tanning leather. In its solid state, it is a semi- transparent substance, without taste or smell. 12. Leather can be produced only from gelatine in a membraneous state, the texture of the skin being neces- sary to the purposes of leather, 13. Glue is extracted from the skin of animals. 14. Size is obtained either from skin in its natnral state, or from leather. 15. Isinglass is gelatine procured from a species of fish called the sturgeon, and is called Ichthyocolla. 16. Gelatine may be obtained from almost any ani- mal substance. Bones produce it in considerable quan- tities, as they consist of phosphate of lime, cemented by gelatine. Horns yield abundance of gelatine. 17. It is from the gelatine of bones that ammonia is produced. By the simple action of water and heat, the gelatine is separated ; and to procure the ammonia, the bones are distilled, by which means, the gelatine is de- composed, and the hydrogen and nitrogen combine in the form of ammonia. The first is a mechanical separation of the ingredients, but the latter, a chemical decomposi- tion. 18. Gelatine may be precipitated from its solution in water by alcohol. The alcohol combining with the wa- ter, while the gelatine is set at liberty. Exp. Take a glass of warm jelly, and add a few drops of alcohol, the gelatine falls down in an insoluble mass, TO CHEMISTRY. r9. Gelatine is composed of Carbon, 47.881 Oxygen, 27.207 Hydrogen, 7.914 Nitrogen, 16.998 100.000 20. Albumen derives its name from the latin, and sig- nifies the white of an egg, in which it exists abundantly, and in its purest natural state is one of the principal con- stituents of all animal solids. It abounds in the serum of blood, the vitreous and crystalline humours of the eye, and the fluid of dropsy. 21. It is coagulable by heat. It is soluble in cold water, previously to coagulation, but not afterwards.— Pure alkalies dissolve it, even after coagulation-. It is precipitated by muriate of mercury, nitro muriate of tin, acetate of lead, nitrate of silver, muriate of gold, infusion of galls and tannin. The acids and metallic oxides co- agulate albumen. 22. Solid albumen may be obtained by agitating white of egg with ten or twelve times its weight of al- cohol. This seizes the water which held the albumen in solution, and this substance is precipitated under the form of white flocks or filaments, which are rendered insoluble by cohesive attraction. 23. Albumen thus obtained is like fibrine, solid, white, insipid, inodorous, denser than water, and without action on vegetable colours. It dissolves in potash and soda more easily than fibrine, and more difficult in acetic acid 24. 100 parts of pure albumen consist of Carbon, 52.883 Oxygen, 23.872 348 INTRODUCTION Hydrogen, 7.5 M Nitrogen, 15.705 100.000 2b. Fibrine is another animal substance ; it is found also in vegetables. It is a soft solid, of a greasy appear- ance, insoluble in water, softens in the air, and becomes viscid, brown and semi-transparent. On hot coals it melts, throws out greasy drops, crackles, and evolves the smoke and odour of roasting meat. It exists in chyle, it enters into the composition of blood ; it forms the prin- cipal part of muscular flesh, and may be regarded as the most abundant constituent of the soft solids of animals. 26. It may be obtained by beating blood as it issues from the veins, with a bunch of twigs. Fil rine soon at- taches itself to the twigs, under the form of long reddish filaments, which become colourless by washing them with cold water. 27. It is solid, white, insipid, without smell, denser than water, does not change the infusion of litmus or vio- lets. When moist, it possesses a species of elasticity.— It becomes yellowish, hard and brittle, by drying. 28. It is composed of Carbon, 53.360 Nitrogen, 19.934 Oxygen, 19.685 Hydrogen, 7.021 100.000 29. Caseous matter is a substance procured from milk. Cheese is obtained from milk by means of rennet, which is a watery infusion ofthe coats of the stomach of a suck- ing calf. It possesses the property of coagulating milk, which is supposed to be owing to the gastric juice with TO CHEMISTRY. 349 which it is impregnated. What remains after the sepa- ration of the curds is called whey, from which may be obtained a substance, by evaporation, called sugar of milk. This substance is sweet to the taste, and is sus- ceptible of undergoing the vinous fermentation. Whey, by combining with oxygen, is capable of being acidified and of forming the lactic acid. 30. The nature and flavour of cheese depend on the cream or oily matter, and likewise, it is said, on a pecu- liar acid, called caseic acid. If both these substances be removed from the cheese, it becomes insipid and totally unfit for food. 31. Colouring matter of blood is a peculiar compound ; it does not exist in any other organized body. To ob- tain it pure, mix blood with 4 parts of sulphuric acid, previously diluted with 8 parts of water, and expose the mixture to a heat of about 160° for 5 or 6 hours, filter the liquid while hot, and wash the residue with a few ounces of hot water. Evaporate the liquid to one half, and add ammonia, till the acid be almost but not entirely saturated. The colouring matter falls. Decant the su- pernatant liquid, filter and wash the residuum from the ammonia. When it is well drained, dry it in a cap- sule. 32. When solid, it appears of a black colour, but be- comes wine red by diffusion through water ; in which, however, it is not soluble. It is destitute of taste and smell. It is soluble both in alkalies and acids. It ap- proaches to fibrine in its Constitution, and contains iron in a peculiar state. One third per cent ofthe oxide may be obtained by calcination, according to Dr. Ure. The incinerated colouring matter weighs l-80th ofthe whole, and the ashes consist of 50 oxide of iron, 7.5 sub-phos- 30 350 INTRODUCTION phate of iron, 6 phosphate of lime with traces of mag- nesia, 20 pure lime, 16.5 carbonic acid. Observation. Berzelius thinks that none of these bod- ies existed in the blood, but only their bases, iron, phos- phorus, calcium, carbon, &c. and that they were formed during the incineration. 33. The buffy coat of inflamed blood is fibrine, from which the colouring matter has been precipitated, from the greater liquidity or slowness of coagulation during the disease. 34. Mucus is one of the primary animal fluids, per- fectly distinct from gelatine. The subacctate of lead does not affect gelatine ; on the other hand, tannin, which is a delicate test of gelatine, does not affect mucus. Both these reagents, however, precipitate albumen ; but the oxymuriate of mercury, which will indicate the presence of albumen dissolved in 2000 parts of water, precipitates neither mucus nor gelatine. Thus we have three distinct and delicate tests for these three different principles. 35. Urea is an animal substance, prepared from urine. It crystallizes in four sided prisms, which are transparenf and colourless, writh a slight pearly lustre. It has a pe- culiar, but not urinous odour. It docs not affect litmus or tumeric papers. It is permanent in the atmosphere. In damp weather it deliquesces slightly. In a strong heat it melts, and is partly decomposed and partly sublim- ed without change. The specific gravity of the crystals is about 1.35. It is very soluble in water. Alcohol at the temperature of the atmosphere, dissolves about 20 percent ; when boiling, considerably more than its own weight. It is decomposed by fixed alkalies and alkaline earths. It unites with most of the metallic oxides, and TO CHEMISTRY. 351 forms crystalline compounds with the nitric and oxakc acids. 36. Urea is composed, according to Dr. Prout, of Hydrogen, 10.80 Carbon, 19.40 Oxygen, 26.40' Xitrogen, 43.40' 100.00 37. Picromel is the characteristic principle of bile.— ft resembles inspissated bile. Colour greenish yellow. Taste intensely bitter at first, which is succeeded by an impression of sweetness. It is-not affected by an infu- sion of galls. The salts of iron and subacetate of lead precipitate it from its aqueous solution. By destructive distillation it affords no ammonia ; hence nitrogen ap- pears not to be a constituent part of this substance. 38. Osmazome is a peculiar substance, extracted from the brain of animals. It is a soft solid, brownish yellow substance, of a greasey glutinous feel, and of a brilliant appearance, like satin. It melts on exposure to heat, though it does not become softened like tallow. Its aqueous solutions afford precipitates, with infusion of galls, nitrate of mercury, and nitrate and acetate of lead. 34. Sugar of milk is a substance obtained from the whey of milk. 40. It is soluble in five parts of cold, and two and a half of boiling water. It is white, of a sweetish taste, and inodorous. It is insoluble in alcohol and ether ; by the addition of a small quantity of sulphuric acid, it may be dissolved in alcohol. It is soluble in acetic and muri- atic acids, and absorbs muriatic acid gas, forming a grey powder. It is decomposed by chlorine and solution of ^52 I$JTRO»VC.TICN caustic potasli. By nitric acid it is converted into -s.m lactic acid. It is decomposed by heat and affords a resi- duum of charcoal 41. According to Berzelius, it consists of Carbon, 45.2.67 Oxygen, 48.348 Hydrogen, 6.385 100.000 42. Sugar of diabetes is a substance obtained from the urine of diabetic persons. It may be procured by pour- ing into the urine a solution of Goulard^s extract of lead, filtering and evaporating the liquid to the consistence of syrup. After some time, it precipitates. The propor- tions of urine vary at different times from 1-30 to 1-17 ef the whole weight. The disease is supposed to be owing, in some measure, to vegetable diet. When heat- ed with nitric acid, it yielded the same proportion of oxalic acid as an equal quantity of common sugar would have done, allowing for the saline substance present.— From experiment, it appears that this substance is not analogous to sugar of milk, but nearer common sugar in its properties. It crystallizes in a similar manner as sur gar of grapes. 43. The beautiful pigment, called Prussian blue, is ob- tained commonly from animal matters, such as blood, horns, hoofs, skin, hair, wool, &c.; but it may be formed without the presence of any animal matter, and may likewise be obtained from a variety of vegetables.— When formed from animal substances, they are first charred, then mixed with potash, and the mixture cal- cined in a covered crucible, the alkali attracts the acid from the coal, and forms with it a prussiate of potash, which being mixed in solution with sulphate of iron, for TO CHEMISTRY. 3"> 3 which the prussic acid has a greater affinity than for the alkali, produces the Prussian blue. 4-1. The muscles consist of bundles of fibres which terminate in a kind of string or ligament, by which they are fastened to the bones. They are the organs of mo- tion ; by their power of dilatation and contraction they put into action the bones, which act as levers in all the motions ofthe body, and form the solid support of its various parts. 45. The muscles are of various degrees of strength or consistence, in different species of animals. - The mammiferous tribe seem, in this respect, to occupy an intermediate place between birds and cold blooded ani- mals, such as reptiles and fishes. 46. The muscles of different animals differ very much in their appearance and properties ; ;;t least, as articles of food. According to Thouvenal, the flesh of the ox- contains the greatest quantity of insoluble matter, and leaves the greatest residuum when dried ; the flesh.of the calf is more aqueous and mucous ; the land and water turtle yields more matter to water, than the muscle of the ox ; snails yield to water a quantity of matter inter- mediate between that given by beef and veal ; the mus- cles of fnogs, cray fish, and vipers, agree nearly with snails, in their yielding a quantity of* matter to water ; but the muscles of fresh water fish, yield a considerably smaller proportion. 47. When meat is boiled, the gelatine, the extrac- tive, and a portion ofthe salts will be separated, while the coagulated albumen and fibrire will remain in a solid *t:de ; hence the ilavour and nourishing nature of scups, which is d^rivL-d from the extractive and gelatine. 48. The ilavour of roasted meat is owing to the •■ preicr.ee of the gelatine, extractive matter, and salts. L"0* 354 INTRODUCTION 49. The skin is that strong thick covering which en- velopes the whole external surface of animals. It i^ formed of two parts, a thin white elastic layer on the outside, called epidermis, or cuticle ; and a much thicker layer, composed of a great many fibres, closely inter- woven, and disposed in different directions, called the cutis, or true skin. Note.—The epidermis is that part ofthe skin which is raised in blisters. 50. The cuticle is transparent, as well as porous, through which the mucous membrane, or true skin is seen, which in the European and American is white or brown% and in the negro, black. 51. The extremities ofthe nerves are spread over the true skin, so that the sensation of feeling is trans- mitted through the cuticle. 52. The cutis, or true skin, appears to be a peculiar modification of gelatine, calculated to resist the action of water, partly by the compactness of its texture, and part- ly by the viscidity of the gelatine. 53. It is from the skin or cutis, that leather is form- ed ; and the goodness of leather, or at least its strength depends, in some measure, on the roughness of the hides. Those easily soluble, as seal skins, afford a weaker leath- er than those which are more difficultly soluble in water The process by which the skins of animals are converted into leather, is called tanning. 51. The cavities between the muscles and skin are usually filled with fat, which lodges in the cells, and im- [».rts to the external form, in the human figure, that jouudness, smoothness andsoftness, which is so attractive, k."n:.mental and beautiful. 55. Bone is the solid, well known substance which gives firmness and strength to animal bodies. The tex- TO CHEMISTRY. 355 ture of bone is sometimes dense, at other times cellular and porous, according to the situation. 56. Bones consist of phosphate of lime, cemented by gelatine, to which it owes its great firmness and solidi- ty- 67. Calcined human bones, according to Berzelius, are composed, in 100 parts, of Phosphate of lime, 81.9 Fluate of lime, 3 Lime, 10 Phosphate of magnesia, 1.1 Soda, 2 Carbonic acid, 2 100.0 58. Fourcroy and Vauquelin found the following to be l he composition of 100 parts of ox bones. Solid gelatine, 51 Phosphate of lime, 37.7 Carbonate of lime, 10 Phosphate of magnesia, 1.3 100.0 According to Berzelius, they are composed, as follows, Cartilage, 33.3 Phosphate of lime, 55.35 Fluate of lime, 3 Carbonate of lime, 3.85 Phosphate of magnesia, 2.05 Soda, 2.45 100.00 59. The earthy salts are retained in their respective places, or interstices, by a membranous or cartilaginous substance, which is found to be indurated albumen. 356 INTRODUCTION 60. The bones of animals acquire a red tinge, in con- sequence of taking madder with their food. The bones of young pigeons will thus be tinged, of a rose colour, in twenty-four hours, and of a deep scarlet, in three days. The bones most remote from the heart are the longest in acquring this tinge. 61. Bones are of extensive use in the arts. In their natural state, or dyed of various colours, they are made into handles of knives and forks, and numerous other ar- ticles. They are also used for the preparation of the volatile alkali, or ammonia, and for making of jelly. 62. Blood is the fluid which first presents itself to observation, when the parts of living animals are divid- ed or destroyed, and which circulates through the veins and the arteries to every part of the body. 33. Recent blood is uniformly fluid, and of a saline taste. Under the microscope, it appears to be compos- ed of a great number of red globules swimming in a transparent fluid. After standing for a short time, its parts separate into a thick red matter, or crassamentum, and a fluid, called serum. 6-1. Blood usually consists of about 3 parts serum to 1 of cruor. 65. The serum is of a pale greenish yellow colour, Its specific gravity is about 1.029, while that of blood it- self is 1.053. It changes syrup of violets to a green, from its containing free soda. At 156° serum coagulates and resembles boiled white of egg. When this coagu- lated albumen is squeezed, a muddy fluid exudes, which has been called the serosity. TO CHEM1STRX. 557 GQ. According to Berzelius, 1000 parts of the serum of bullock's blood consist of Water 905 Albumen 79.99 Lactate of soda and extractive matter 6.175 Muriate of soda and potash. 2.565 Soda and animal matter 1.52 Loss 4.7S 1.000 1000 parts of serum of human blood consist of Water 905 Albumen 80 Muriate of potas and soda 6 Lactate of soda with animal matter 4 Soda, phosphate of soda with animal matter 4.1 Loss 9 1000.0 67. There is no gelatine in serum. 68. The cruor has a specific gravity of 1.245. By making a stream of water flow upon it, till the water runs off colourless,it is separated into insoluble fibrine, and the soluble colouring matter. A little albumen has likewise been found in cruor. The proportions of the former two are 64 colouring matter and 36 fibrine in 100. 69. Urine, in its natural state, is transparent, of a yellow colour, a peculiar smell and saline taste Its pro- duction as to quantity, and in some measure quality, de- pends on the seasons, and the peculiar constitution of the individual, and is likewise modified by disease. It is ob- served that prespiration carries off, more or less ofthe fluid of the body which would otherwise have passed off 358- INTRODUCTION by urine ; so that a profusion ofthe former#is attended by? a diminution of the latter. 70. Urine is composed ofthe following parts. Water t Urea 2. Phosphoric acid 3' Phosphate of lime 4 --------- of magnesia 5 —------ of soda 6 --------- of ammonia 7 Lithic acid 8 Rosacic acid 9 Benzoic acid 10 Carbonic acid 11 Carbonate of lime 12 Muriate of soda 13 -------of ammonia 14 Gelatine 15 Albumen 1G Resin 17 Sulphur 18 71. The urine undergoes considerable changes by dis- eases, a knowledge of which is of importance. In inflam- matory diseases it is of a red colour, small in quantity and peculiarly acrid, but deposits no sediment on stand- ing. Corrosive muriate of mercury throws down from it a copious precipitate ; towards the termination of the dis- ease, it becomes more abundant, and deposits a copious pink coloured sediment consisting of rosacic acid, with a little phosphate of lime and uric acid. 72. In jaundice the urine is of a deep yellow colour, capable of staining linen. Muriatic acid renders itgreen, and this indicates the presence of bile. TO CHEMISTRY. 339 */3. In hysterical affections it is copious, limpid and colourless, containing much salt, but scarcely any urea or gelatine. 74. In dropsy the urine is generally loaded with albu- men, so as to become milky, or even to coagulate by heat, or on the addition of acids. 75. In dropsy from diseased liver no albumen is pres- ent, but the urine is scanty high coloured, and deposits the pink coloured sediment. 76. In dyspepsy or indigestion, the urine abounds in gelatine, and putrefies rapidly. 77. In rickets the urine contains a great quantity of calcareous salt, which is found to be the oxalate of lime. 78. In diabetic patients, the urine is sometimes so loaded with sugar as to be capable of being fermented into a vinous liquor. Sometimes, however, the urine is not sweet, but insipid. 79. Urine has been employed for making phospho- rus, volatile alkali and sal-ammoniac. It is used in a pu- trid state for scouring woolens. 80. Tears compose that peculiar fluid which is ap- propriated to lubricating the eye, and which is emitted in considerable quantities when we express grief by weep- ing. 81. This liquid is transparent and colourless like wa- ter ; it has scarcely any smell, but its taste is always per- ceptibly salt. Its specific gravity is somewhat greater than that of distilled water. It gives to paper stained with the juice of violets, a permanently green colour, hence we infer the presence of a fixed alkali. It unites with water, whether cold or hot, in all proportions. Al- kalies unite with it readily and render it more fluid. The mineral acids produce no apparent change upon it. Ex- 360 INTRODUCTION posed to the air, it gradually[ evaporates and becomes thick. 82. Tears are composed of 1 Water, 2 Mucus, 3 Muriate of soda, 4 Soda. 5 Phosphate of lime, 6 Phosphate of soda. The saline parts of tears amount only to about 0.01 of f;ie whole. 83. Bile is a bitter liquid of a yellowish or greenish yellow colour, more or less viscid. Specific gravity greater than that of water, common to a great number of animals, the peculiar secretion of their liver. It is the prevailing opinion of physiologists, that the bile is separated from the venous, and not from the arterial blood. The veins which receive the blood distributed to the abdominal viscera, unite into a large trunk called the vena porta, which divides into two branches, that pene- trate into the liver, and divide into innumerable ramifica- tions. The last of these terminate partly in the biliary ducts, and partly in the hepatic veins, which restore to the cir- culation that portion of blood which is not necessary for the formation of bile. This liquid passes directly into the duodenum, when the animal has no gall-bladder; but when it has one, as more frequently happens, the bile flows back into It by the cistic duct, and remaining there for a longer or shorter time, experiences remarkable al. terations. Its principal use ssems to be, in promoting digestion, in concert with pancreatic juice. 84. Ox bile is usually of a greenish yellow colour, rarely deep green. It is at once very bitter and slight- ly sweet. Its taste h scarcely supportable. Its smell. TO CHEMISTRY. 361 though feeble, is easily recognizable, and approaches somewhat to the nauseous odour of some fatty matters «vhen they are heated. Its specific gravity is about 1.026 at 43° F. Ox bile is composed of Water 7.00 Resinous matter 05 Picromel 69.00 Yellow matter 4.00 Soda 4.00 Phosphate of soda 2.00 Muriate of soda 3.5 Sulphate of soda 0.8 Phosphate of lime 1 2 Oxide of iron a trace 93.0 86. Brain is a soft pulpy substance, with little or no smell. Exposed to a gentle heat, moisture evaporates, it shrinks to about a fourth of its original bulk, and be- comes a tenacious mass of a greenish brown colour; when completely dried, it becomes solid and friable like old cheese. In its natural state, or moderately dried, it readily forms an emulsion by trituration with water and is not separated by filtration. This solution lathers like soap suds, but does not turn blue vegetable infusions green. 87. Its constituents, according to Vauquelin, are, in 100 parts, Water 80 White fatty matter 4.53 Reddish fatty do 0.7 Albumen 7.0 Osmazome 112 31 362 INTRODUCTION Phosphorus 1-5 Acids, sails and sulphur 5.15 100.00 C8. The medulla oblongata and nerves have the same chemical composition as the brain. 89. Gastric Juice is separated by glands placed be- tween the membranes which line the stomach ; and from these it is emitted into the stomach itself. It reduces the aliment into a uniform mass, even when out ofthe body. It acts in the same manner on the stomach after death ; which proves that the action is chemical, and not depen- dent on vitality. 90. The gastric juice affects the solution of aliments included in tubes of metal, consequently defended from any trituration. 91. Though there is no trituration in membraneous stomachs, this action powerfully assists the effect of the digestive powers in animals with muscular ones, such a9 fowls. 92. The gastric juice acts by its solvent power, and not as a ferment This appears evident from there not being any disengagement of air in ordinary digestion; neither is ther^ any inflation, or increase of heat, nor any other ofthe ordinary phenomena of fermentation. PRACTICAL QUESTIONS. What is animalization? How may animals as well as vegetables be consid- ered ? Cau the animal process be compared with that of the chemical ? To what do you compare the process in (ho stom- ach ? TO CHEMISTRY. 363 What kind of apparatus do the bowels constitute ? How are organized bodies contrived? Do animals agree with vegetables in their composi- tion T: What do animal substances afford by distillation? What are the fundamental principles of animal com- pounds V From- what cause arises the difficulty of analizing«ani- mal substances-?' What are the peculiar products of animal organiza- tion ? What is gelatine?" What are its properties? From what is leather produced ?' From what is glue obtained ? From what size ? What is isinglass ? From what can gelatine be obtained? From what is ammonia obtained ? How can gelatine be separated from its solution ? Of what is gelatine composed ? What is albumen ? What are its properties ? How can solid albumen be obtained ? What are the properties of solid albumen ? What is fibrine ? How can it be obtained ? What are its peculiar properties ? Of what is it composed ? What is caseous matter ? On what does the nature and flavour of cheese de- pend ? How do you obtain the colouring matter of blood? What are its characteristics ? 364 INTRODUCTION What is the buffy coat of inflamed blood ? How do you distinguish mucus from gelatine and albu men? What is Urea ; and what are its properties ? Of what is it composed ? What is Picromel ? What is osmazome ? What are its properties '! What is sugar of milk ? Of what does it consist ? What is sugar of diabetes ? From what is prussian blue obtained ? Of what do muscles consist 1 Whence does roasted meat derive its flavor ? Of what is skin formed ? How is the sensation of feeling transmitted through the cuticle ? With what are the cavities between the muscles and the skin filled ? What is bone ? To what do bones owe their great firmness and solid- ity ? "Of what are calcined human bones compose J ? Of what do ox-bones consist? Of what is that composed which appears to retain the earthy salts in their places ? What is the consequence of giving madder to animals in their food ? Are bones of any use in the arts? What is blood ? What appearance has recent blood ? Of what does blood consist? What are the properties of serum? Of what does it consist ? TO CHEMISTRY. 365 What is said of cruor ? What are the properties of urine ? Of what is it composed ? Does urine undergo any change by disease 1 How is it in jaundice? How in hysterical affections ? I low in dropsy ? How in dyspepsia ? How in rickets 1 How.in diabetic patients? Is urine employed in the arts ? What are the properties of tears ? Of what are tears composed ? What are the properties of bile ? What are the properties of ox-bile ? : Of what is it composed ? What is brain ? Of what is it composed? ' What is the gastric juice and its office ? Does the gastric juice act by its solvent powers or by trituration 1 How do you prov-3 that this action is not by fermenta- tion ? CHAP. XXXViE Of Respiration. 1. Respiration is a function in animals which consists in the alternate inhalation of a portion of air into an or- gan called the lungs, and its subsequent exhalation. 306 INTRODUCTION 2. In order to form any determinate opinion of the phenomena of respiration, there are two things to be considered in the first place, viz. the mechanical and the chemical part of the process. 3. The mechanism of breathing depends on the al- ternate expansions and contractions of the chest. When the chest dilates, the cavity enlarges, and the air ru-hes in at the mouth,to fill up the vacuum formed by this dila- tation, when it contracts, the cavity is diminished and the air again forced out. 4. The lungs likewise contract and expand in breath. ing, in consequence of that ofthe chest. The lungs, to- gether with the breast and largest bloodvessels, in a man- ner fill up the cavity ofthe chest; it must therefore pre- viously expand in order for the dilatation of these organs. When it contracts, it presses on the lungs and forces the air out of them, in a manner similar to bellows. 5. The chest is a large cavity in the upper part of the body, contained within the ribs, the neck and the dia- phragm. 6. The diaphragm is that membrane which separates the chest from the lower part of the body, which is mus- cular and capable of great dilatation and contraction. When this contracts the space within the chest is dimin- ished, and of course the air is pressed out from the lungsj On the other hand, when the membrane dilates, the cav- ity is enlarged, and the external air rushes in to keep up the equilibrium, so that as long as this action of the diaphragm continues, respiration is carried on. 7. Besides the motion of the diaphragm, there is also a muscular motion of the ribs, which contribute towards enlarging or diminishing the cavity ofthe chest. These lire alternately drawn edgewise to assist the contraction. TO CHEMISTRY. 367 and stretched out like hoops of a barrel, to contribute to the dilatation ofthe chest. 8. These two muscular contractions, viz. of the dia- phragm and the ribs, are to be considered as the causes of the contraction and expansion of the chest ; and the air rushing into and being expelled from the lungs, is only the effects of those actions. Illustration. Open the mouth without any action of the chest, the air will not rush in until by an interior muscular action, a vacuum be produced. 9. lu general, this alternate action of dilatation and contraction, in a healthy person, is between fifteen and twenty times in a minute. 10. Previously to our proceeding to the chemical effects of respiration, it is necessary that we should un- derstand the theory ofthe circulation ofthe blood. 11. In the system there are two kinds of blood ves- sels, the veins and arteries, each possessed of peculiar functions. 12. The arteries convey the blood from the heart to the extremities of the body ; and the veins bring it back to the heart. 13. The heart is a muscular cavity, which possesses a power of dilating and contracting itself, forthe purpose of alternately receiving and expelling the blood, in order to carry on the process of circulation. 14. The blood in the arteries is of a beautiful red colour, but when it passes into the veins it becomes pur- ple. This change depends upon various circumstances. In the first place, the blood, during its passage through the arteries undergoes a considerable alteration, some of its constituent parts are gradually separated from it, for the purpose of nourishing the body, and of supplying the various secretions. Consequently, the florid arterial c«l- 368 INTRODUCTION our of the blood changes by degrees to a deep purple, which is its constant colour in the veins. During the return ofthe blood through the veins, it is renewed by fresh chyle or imperfect blood, which has been produc- ed by food. It receives also lymph from the absorbant vessels. In consequence of these several changes, the blood returns to the heart in a state different from that in which it left it. It is charged with a greater propor- tion of hydrogen and carbon, and is no longer fit for the nourishment of the body, or other purposes of circula- tion. 15. The heart is divided into two cavities, called the right and left ventricles. The left ventricle is the re- ceptacle for the pure arterial blood, previously to its circulation ; whilst the venous or impure blood, which returns to the heart, after having circulated, is received into the right ventricle, previously to its purification. 16. As the blood conveys nourishment to the body in the course of circulation, there must be some process by which it can be supplied with the means of imparting this nourishment ; this is by respiration, or the chemical part of it. 17. When the venous blood enters the right ventri- cle of the heart, this organ contracts by its muscular power and throws the blood through a large vessel, cal- led the pulmonary artery, into the lungs, which are con- tiguous, and through which it circulates by innumerable small branches. It is here brought in contact with the air which we breathe. 18. The venous blood which enters the lungs from the pulmonary artery, is charged with carbon, to which it owes its dark purple colour. When the oxygen of the atmosphere is applied to the interior of the air vesicles of the lungs, it combines with the carbon of the blood, TO CHEMISTRY. 369) forms carbonic acid, which, to the amount of from 4.5 to. 8 per cent of the bulk of the air inspired is immediately exhaled. 19. It does not appear that any oxygen or nitrogen* the two constituents of the atmosphere, are absorbed by the lungs during respiration ; for the volume of carbonic acid generated, is exactly equal to that of the oxygen ■which disappears ; now we know that carbonic acid contains its own volume of oxygen. 20. The change of the blood from the purple venous. to the bright red arterial, seems owing to the discharge of the carbon, with which it is impregnated during the circulation, in consequence of its affinity for oxygen. 21. An ordinary sized man, in health, consumes about forty-six thousand cubic inches of oxygen in a day, which is equal to one hundred and twenty-five cubic feet of atmospheric air. The same quantity of carbonic acid is expelled. 22. About twenty respirations are made in a minute, or, a man breathes twice for every seven pulsations. 23. It has been found that after swallowing intoxicat- ing liquors, the quantity of carbonic acid formed in res- piration was diminished. The same thing is said to hap- pen under a course of mercury, nitric acid, or vegetable diet. 24. Carbon appears to exist in a greater proportion in blood, than in any other organized animal matter.— By this means, the blood, after supplying its various se- cretions, becomes loaded with an excess of carbon, which is carried off by respiration ; and the formation of new chyle from the food, affords a constant supply of carbo- naceous matter. 370. INTRODUCTION, PRACTICAL QUESTIONS. What is respiration ? What is necessary in order to form a correct opinion) of respiration t On what does the mechanism of breathing depend ? Is the expansion and contraction of the chest in conse- quence of that of the lungs ? What is the chest ? What is the diaphragm ? What office does it perform ? What office do the ribs perform ? How are these muscular contractions of the diaphragm- and ribs to be considered ? How do you illustrate this ? How often is this alternate dilatation and contraction ? How many kinds of blood vessels are there ? What are their offices ? What is the heart ? How is the blood in the veins and arteries, what are the changes produced, and the causes of those changes? How is the heart divided ? What is the process by which the blood can be sup- plied with the means of affording nourishment to the system ? How is the blood brought in contact with the air which we breathe ? To what does the blood owe its purple colour ? Is oxygen or nitrogen absorbed by the lungs r To what is the change of the blood from the purple to the red arterial owing ? How much oxygen do we consume in a day ? How many respirations are made in a minute ? TO CHEMISTRY. 37J How is the quantity of carbonic acid diminished in respiration ? How is it that the blood acquires such a quantity of carbon ? CHAP. XXXVIII. On Animal Heat, &c. 1. During respiration, heat is disengaged. It has been calculated that the heat produced by respiration in twelve hours, in the lungs of a person in health, i« such, as would melt about one hundred pounds Of ice. 2. Venous blood has been found by experiment to have less capacity for heat than arterial blood ; and the blood in passing from the arterial to the venous state during circulation, parts with a portion of caloric, by means of which, heat is diffused through every part of the body. 3. The heat of animals is various, according to the variety of species of animals, the difference of seasons and climates, and the state of the same animal, at differ- ent periods. 4. Animals have been very properly divided into hot and cold blooded animals ; reckoning those to be hot which are near our own temperature ; and all others cold, whose heat is much below ours, or which give us the sensation of cold ; such as most insects. Though the heat of a swarm of bees raised a thermometer to 97°, indicating a degree of heat but little, if any inferior to our own. To this class, belong muscles and oysters, snails, frogs, serpents, Lc. 372 INTRODUCTION 5. The human kind forms the lowest gradation in the ^lass of hot animals ; the mean heat of the human body as deduced from a variety of experiments, is about 97°. 6. With respect to quadrupeds, the heat of their bodies will raise the thermometer three or four degrees highei than those ofthe human kind ; and ihc bodies of birds arc still warmer. 7. It appears from a variety of experiments and ob* servations, that those animals which are furnished with Jungs, and which continually receive the fresh air in great quantities, have a power of keeping themselves at a temperature considerably higher than the surrounding atmosphere ; but animals that are not furnished with respiratory organs, are very nearly at the same tempera- ture with the medium in which they live. 8. Among the hot animals, those are the warmest which have the largest respiratory organs ; consequent- ly breathe the greatest quantity of air in proportion to their bulk. Illustration. The respiratory organs of birds are great- er, in proportion to their bulk, than those of any other animals ; and birds are known to have the greatest degree of animal heat. 9. From observations and experiments made by Dr. Crawford, it appears that the production of animal heat depends on a process analogous to chemical affinity, and which is on the following principles. Oxygen gas con- tains more specific heat in proportion to its temperature and weight, than carbonic acid gas. The Hood is re- turned to the lungs impregnated with the carbonaceous principle, but has less attraction for that principle than oxygen has. In the lungs, therefore, the carbon quits the blood to unite with the oxygen which is inhaled from the atmosphere. By this combination, the oxygen TO CHEMISTRY. 373 gas is changed into the carbonic acid gas, and deposits part of its heat. The capacity of blood for heat is, at the same time, increased ; the blood, therefore, receiv- ing that portion of heat which was detached from the air. 10. The arterial Wood in its passage through the ca- pillary vessels, is again impregnated with the carbon and the hydrogen, by which its capacity for heat declines ; it, therefore, in the course ofthe circulation, gradually gives out the heat which it had received in the lungs, and diffuses it over the whole hody. Thus it appears, that in its circulation through the lungs, the blood is continually discharging carbon and absorbing heat, and that in its passage through the other parts of the body, it is imbibing carbon and emitting heat. 11. By the different capacities which Wood possesses for heat in its different states, it is capable of supplying the different parts of the body with warmth, while its own temperature remains the same. 12. If this difference of capacity for caloric did not exist, the extremities of the body could not be properly supplied with heat from the lungs, unless the lungs them- selves were exposed to a degree of heat, which would be prejudicial, and perhaps such as no organized being could support, without destruction. 13. It has been proved, by a variety of experiments, that when an animal is placed in a cold medium, the ve- nous blood acquires a deeper hue, that a greater quan- tity of air is vitiated in a given time, consequently that more heat is absorbed by the blood. 14. Perspiration prevents an accumulation of heat in the system beyond what is salutary ; if this be stopped, the heat increases. This is probably the principal cause of heat in fevers, the pores being closed there is no vent 32 374 INTRODUCTION for the heat which is generated, which occasions thost1 burning sensations. 15. One ofthe most considerable secretions is insen- sible perspiration ; this is constantly conveying from the body heat in its latent state. 16. In violent exercise, the caloric is increased, but in a healthy person, it is carried off by the perspiration which succeeds. 17. Inconsequence of the economy of perspiration, persons are enabled in all climates, and in all seasons, to preserve their bodies of an equal temperature, that is with regard to the blood and the internal parts of the body ; for those parts of the body which are in immedi- ate contact with the atmosphere will occasionally be- come warmer or colder, than the internal or more shel- tered parts. But if the ball of a thermometer be applied under the tongue, it will he found to indicate scarcely any difference in the state of the blood, whatever may be the changes in the atmosphere. Illustration. Persons have been known to remain some minutes in a heat little inferior to that of boiling water, without increasing in any great degree the internal heat of the system. In some instances, the heat has been much greater than boilingwatcr. PRACTICAL QUESTIONS. Is. any heat disengaged during respiration ? Has venous and arterial blood the same capacity for heat ? How is heat diffused through every part of the body i h the heat of animals the same at all tiiocs ? With regard to heat, how have animals been divided? What gra.iation do the human kind form in the class of hot annua U ? TO CHEMISTRY. 375 How is it with regard to quadrupeds ? What animals have the power of keeping their tem- perature above that ofthe atmosphere ? What animals are the warmest 1 What is Dr. Crawford's theory of animal heat ? What office does the arterial blood perform ? How does the blood supply the different parts of the body with heat while its- temperature remains the same ? What is the effect of placing an animal in a cold me- dium ? What prevents a too great accumulation of heat in the system ? What is the cause of heat in fevers ? What is one of the most important secretions ? Violent exercise increases heat; does it not cause for ver ? How is it that persons in all climates and seasons are capable of preserving an equality of temperature ? DICTIONARY OF TERMS. A. Absorption, the conversion of a gaseous fluid into a li- quid, or solid, on being united to another substance. Abstraction, a term used to denote _ when an acid or other fluid is repeatedly poured upon any substance and distilled off, with a view to change the state or composi- tion. Acerates, salts formed by the union of aceric acid with a base. Aceric acid, a substance obtained from the juice of the- maple, having acid properties. Acescent, a term applied to those substances which be- come sour spontaneously. Acetates, substances formed by the uniou of acetic acid with salifiable bases. Acetic acid, concentrated vinegar. Acetous, of, or belonging to vinegar. Acid, a substance, which, when united with alkalies, earths and metallic oxides, forms salts. Acidifiable, capable of being converted into an acid. Acidules, a term applied by the French chemists to those salts which we denominate by the term bi, cr sti- per. Adhesion. See cohesion. Adopter, a vessel with two necks placed between a re- tort and receiver, to increase the length of the former. ' 3* 3r8 INTRODUCTION Aerial acid. Carbonic acid, Aerometer, an instrument for ascertaining the mean bulk of the gases. Affinity. See attraction. Agaricus, the mushroom, a genus of the order Fungi. Agaricus mineralis, one of the purest species of carbo- nate of lime. Aggregate. When two bodies are united together, the mass is called an aggregate, and preserves the chemical properties of its constituents. Air, the permanently elastic fluid which surrounds the globe; the term is now exclusively confined to the at- mosphere ; that of gas to other invisible and elastic fluids. Alabaster, sulphate of lime. Albumen, the white of egg, and one of the constituent principles of all animal solids. Alburnum, the inner white bark of trees. Alcohol, a term applied to pure spirit. Alembic, a still. AlkoJicst, the pretended universal solvent of the an- cients. Alkali, a term derived from the word kali, the Arabic name of a plant, from the'ashes of which, one species of alkaline substances may be obtained. Alkalescent, any substance in which alkaline proper- ties are beginning to be developed. Alloy. When an inferior metal is added to a precious one, the part added is called the alloy. Thus when cop- per is added to. gold, the former is the alloy. Aludel, a vessel used in sublimation. Alum. Sulphate of alumina. Alumina, one of the primitive earths, constituting the plastic principle of all clays, loams, &C, TO CHEMISTRY. 379 Acetate of alumina, a combination of acetic acid with a salifiable base. Amalgam, a combination of mercury with other metal- lic substances. Amber, a hard, brittle, tasteless substance, sometimes perfectly transparent, but mostly semi-transparent, or opaque, and of a glossy surface. It is chiefly of a yel* low or orange colour. Ammonia, volatile alkali, a substance prepared from animal matter ; its constituents are hydrogen and nitro- gen. When pure, it is an invisible gas, having a very pungent odour. Analysis, the art of separating the constituents of bod- ies, so as to discover their properties. Anhydrous, a term applied to salts when destitute of water. Antimony, a word used in commerce, to denote a me- tallic ore, consisting of sulphur combined with the met- al. The latter is properly called metal by chemists. Apyrous. Bodies which sustain the action of a strong heat for a length of time, without change of figure or other properties, have been called apyrous, or refracto- ry- Aqna fortis, a name given to an impure and weak ni- tric acid, commonly used in the arts. Aqua regia, so named from its property of dissolving gold, now called nitro-muriatic acid. Aqua vitae. Spirit of the first distillation ; the distil- . lers call it, low wines. Archil, a species of moss growing upon rocks in the Cape Verd and Canary Islands, of which a rich purple tincture is made. . Iromatics, plants which possess a fragrant smell, united with pungency, and at the same time are warm to the taste, are aromatics. 380 INTRODUCTION Arsenic, a metal of a bluish white colour, subject to tarnish, and turns first yellowish, then black, on expo- sure to the air. It sublimes in close vessels, and burns with a small flame, if oxygen be present. Athanor, a furnace used by ancient chemists ; now fal- len into disuse. Atmometer, an instrnment to measure the degree of exhalation from a humid surface in a given time. Atmosphere, the invisible elastic fluid which surrounds the earth. Atropa, a poisonous vegetable principle, probably alka- line, lately extracted from the Atropa Belladonna, or deadly night shade. Attraction, the tendency which bodies possess to ap- proach each other. Aurum Musivum, a combination of tin and sulphur, the bi-sulphuret of tin. Azote. Nitrogen gas. B. Balloon, a glass receiver of a spherical form. Balsams, substances of a resinous nature, which spon- taneously become concrete, and are capable of affording benzoic acid when heated alone, or with water. Balsam of sulphur, a solution of sulphur in oil. Baldwin's phosphorus, ignited nitrate of lime. Barium, the metallic basis ofthe earth barytes. Barilla, a term given in commerce to the impure soda. imported from Spain and the Levant. Barolite. Carbonate of barytes. Base, or basis, a chemical term usually applied to al- kalies, earths and metallic oxides, in their relation to acids and salts. It is sometimes also applied to the par- ticular constituents of an acid or an oxide, on the suppo- TO CHEMISTRY. 381 sition that the substance combined with the oxygen, &c. i9 the basis of the compound to which it owes its particu- lar qualities. Bath, a vessel partly filled with sand, water, or some other substance, in order to produce a uniform heat ta retorts and other glass vessels, in some operations. Beer, a liquor made of malt and hops. Bell metal, a composition of tin and copper. Benzoic acid, an acid obtained from Benzoin. Bi, a term used to express an excess of some ingredi- ent in many chemical compositions. Bile, a bitter liquid of a yellowish colour, the peculiar secretion of the liver of some animals. Bismuth, a metal of a yellowish or reddish white col- our, little subject to change in the air; somewhat harder than lead, and very little malleable. Bistre, a brown pigment consisting of the finer parts of wood soot, separated from the grosser by washing. Bittern, the water which remains after the crystalliza- tion of common salt in sea water, or the water of salt springs. It abounds with sulphate and muriate of lime. Bitumen, this term includes a number of inflammable mineral substances burning with flame in the open air, such as Naphtha, Petroleum, Barbadoes tar, &c. Black Jack, an ore of zinc. Black Lead, Plumbago. Black Wadd, an ore of manganese. Bleaching, a chemical art by which the various articles used for clothing are deprived of their natural dark col- our, and rendered white. Blende, an ore of zinc. Boron, the combustible basis of boracic acid. Brandy, a spirit distilled from wine. 382. INTRODUCTION- Brass, a compound metal consisting of copper combined I with about one third of its weight of zinc.. Brimstone. Sulphur.. Bronze, a mixed metal, consisting chiefly ofcopper,with^ a small proportion of tin, and sometimes other, met- als. Brucine, a new vegetable alkali, lately extracted from the bark of the false angustura. Brycea antidysen- terica. Brunswick green, an ammoniaco-muriate of copper,. used as a pigment. Butters of the metals, now called chlorides.. e. Cadmium, a new metal, discovered in 1817, in a car-..- bonate of zinc, and the silicates of zinc. The name was formerly applied to zinc. Caffein, a name given to a substance obtained from un- roasted coffee. Cajeput oil, a volatile oil obtained from the leaves of. the cajeput tree. Calaminer a native carbonate of zinc. Calcareous, partaking ofthe nature of lime. Calcareous spar, crystallized carbonate of lime. Calcination. The fixed residues of such matters as have undergone combustion, are called cinders in com- mon language, and calces or oxides, by chemists ; the op- eration when considered with regard to these, calci- nation. Calcium, the metallic basis of lime. Calculus, a name usually given to all hard concretions not partaking of bone, formed in the bodies of ani- mals Tu CHEMISTRY '383 <'alonc, the matter of heat, or the agent to which the "phenomena of heat and combustion are-applied. Calorimeter. An instrument contrived to measure the heat given out from bodies in cooling, from the quantity of ice it melts. Cameleon Mineral. When pure potash and black oxide of manganese are fused together in a crucible, a com- pound is obtained, whose solution in water,at first green, passes spontaneously through the whole series of colour- ed rays to the red; from this cirumstance the name ca- meleon has been given to it. Carbon, the pure inflammable part of charcoal, or the diamond. Carbonates, compounds of carbonic acid with salifiable bases. Carburets, compounds of carbon with any other sub- stance, as carburet of iron, steel. Carmine, a red pigment prepared from cochineal. Caramel. The smell exhaled from burnt sugar. Case hardening, when the surface of iron is converted to steel by being inclosed in a box with animal or vege- table charcoal, and subjected to the heat of a forge. Ca-uticity, the power which some bodies possess te combine with the principle of organized substances. so rapidly as to destroy the parts. Cement. Whatever is employed to unite things ofthe same, or of different kinds ; as lute, glue, solder, &c. Cementation, a chemical process which consists in sur- rounding a body in the solid state, with the powder of some other bodies, and exposing the whole for a time in a closed vossel, to a degree of heat not sufficient to fuse the contends. Cerasin, a name given to the gummy substances which fcwell in cold water, but do not readily dissolve in it. 384 INTRODUCTION Cerin, a peculiar substance which precipitates on evap- oration from alcohol, which has been digested on grated cork. The term is also applied to common wax which dissolves in alcohol. Cerium, the name of a metal found in cerite, a mineral ef Sweden. Ceruse. Subcarbonate of lead. Cetine. Spermaceti. Chalk. Carbonate of lime. Charcoal, the residuum of vegetable substances burnt in close vessels. Chlorates, compounds of the chloric acid with salifia- ble bases. Chlorides, compounds of chlorine with combustible bod- ies. Chlorine, a simple substance, the base of what was for- merly called oxymuriatic acid gas. Chhrophyle, the green matter of the leaves of plants. Chromium, the name of a metal extracted from the na- tive chromate of lead or iron. Cinchonin, a substance obtained from cinchona or the peruvian bark. Cinnabar. Mercury united to sulphur. Cistic oxide, a variety of urinary calculi. Citric acid, the acid obtained from limes and lem- ons. Clarification. The process of freeing a fluid from he- terogeneous matters. Clay, aplastic substance whose basis is alumina. Coake, the residuum ofthe combustion of coals in close vessels. Coal, an inflammable mineral substance well known Coal-gas. Carburetted hydrogen. TO CHEMISTRY. 385 Coating, a substance applied to the bottom of retorts to defend them from the too great action of heat. Cobalt, a brittle, somewhat soft, but difficultly fusible metal of a reddish grey colour and of little lustre ; so cal- led from Cobalus, the demon of mines. Cochenilin, the red colouring matter of cocheneal. Cohesion, that power by which the particles of bodies are held together. Cohobation, redistillation of the same liquid from the same materials. Colcothar. The brown red oxide of iron, which re- mains after distilling the acid from sulphate of iron. Cold. The privation of heat. Columbium, a metal of a dark grey colour, resembling in lustre iron. Combination. The intimate union of the particles of different substances by chemical attraction, so as to form a compound possessed of new and peculiar proper- ties. Combustible, a body which in its rapid union with others, causes a disengagement of heat and light. Combustion. The disengagement of heat and light which accompanies chemical combinations. Congelation, the abstraction of heat from bodies, in such quantities as to cause them to assume solid forms. Copper, a metal of a peculiar reddish brown colour-, hard, sonorous, very malleable and ductile, and of con- siderable tenacity. Copperas. Sulphate of iron. Corrosive sublimate, perchloride'of mercury. Cream of tartar, bitartrate of potash. Crocus Mart'ts. The reddish yellow oxide of iron. Cyrophorus, an instrument invented to demonstrate the 33 386 INTRODUCTION relation between evaporation at low temperatures, and the production of cold. Crystal, a regular geometrical figure,fcrmed when flu- id substances are suffered to pass with adequate slowness to the solid state. Cupel, a shallow earthen vessel resembling a cup, made of bone ashes and used in assaying. Cupellation. The refining of gold by ecorification with lead on a cupel. Cyanogen. The compound base of prussic acid. Now called Prussine. D. Daphnin, the bitter principle of Daphne Alpina. Datura, a vegetable alkali obtained from Datura Stra- monium. Decantation, the act of pouring off the clear liquor from a precipitate or sediment. Decoction, the operation of boiling. The term is also used to denote the product of the operation itself. Decomposition, the separating of the component parts or principles of a substance. Decrepitation. The crackling noise which several salts make when suddenly heated, accompanied with a violent exfoliation of their particles. Delphinia, a vegetable alkali dicovered in Staves- acre. Deliquescence, the spontaneous assumption of the fluid state by certain saline substances when left exposed to the air, in consequence of their affinity for water. Dephlegmation, any method by which bodies are depriv- ed of water. TO CHEMISTRY. 387 Dephlogisticated, deprived of phlogistion or the inflam- mable principle. Dephlogisticated air. The same with oxygen gas. Derbyshire spar, fluate of lime. Destructive Distillation, is when a substance is exposed to distillation, until it has undergone the whole power of the furnace. Detonation, a sudden combustion and explosion. Dew, the moisture insensibly deposited on the surface ofthe earth, from the atmosphere. Digestion, the slow action of a solvent upon any sub- stance. Digestive salt, muriate of potash. D.igester, a vessel invented to prevent the loss of heat by evaporation ; by which the solvent power of water is greatly increased. Distillation. The vaporization- and subsequent conden- sation of a liquid, by means of an alembic, or still and re- frigeratory ; or of a retort and receiver. Docimastic Art, the art of assaying metals. Dragon's bloody a brittle dark coloured resin, imported from the East Indies. Ductility, that property or texture of bodies, which renders them capable of being drawn out in length, while their thickness is diminished; this term is almost exclur sively applied to metals. Dyeing, the art of fixing upon cloth of various kinds any colour, in such a manner as that they shall not be easily altered by those agents to which the cloth maybe expos* ed. E. Edulcoration. The purification of a substance by washing with water. 388 INTRODUCTION Effervesccnce,the commotion produced in fluids by some part of the mass suddenly taking the elastic form and es- caping in numerous bubbles. Efflorescence, the effect which takes place when bodies spontaneously become converted into a dry powder. It is almost always occasioned by the loss of the water of crystallization in saline bodies. Elain, the only principle of solid fats. Electricity, so named from electron amber, a simple substance supposed to pervade all nature. Eliquation, an operation whereby one substance is separated from another by fusion. Elutriation, the process of washing, by which the light- er parts are carried off, while the heavier metallic ones subside to the bottom. Emetin, a substance prepared from ipecacuanha root. Emulsion, an imperfect combination of oil and water. Empyreuma, a peculiar disagreeable smell arising from the burning of animal matters in close vessels. Epidermis, when used with respect to animals, the scarf skin, with respect to vegetables the external cover- ing of the bark. Epsom salt. Sulphate of magnesia. Equivalents, a term used to express the system of atoms or definite proportions. Essences. Solutions of volatile oils in alcohol. Ether, a very volatile fluid produced by the distillation of alcohol with an acid. Ethiops mineral. Protosulphuret of mercury. Evaporation, a chemical operation usually performed by applying heat to any compound substance in order to dispel the volatile parts. TO CHEMISTRY 389 Extract, is a term used to denote the substance of the consistence of a paste, obtained by decoction of some veg- etable substance. F. Fecula. Starch. Fermentation, an internal motion in fluids by which they undergo spontaneous changes ; and carbonic acid is disengaged. Ferrocyanates, combinations of ferroprussic acid with salifiable basis Ferrurctted Chyazic Acid, ferroprussic acid. Fribrin, a peculiar organic compound found both in vegetables and animals. Filtration, an operation by means of which a fluid is mechanically separated from particles mixed with it. Firedamp, carburetted hydrogen. Fixed air, carbonic acid gas. Fixityr the property by which bodies resist the action of heat, so as not to rise in vapour. Flake white, the oxide of bismuth. Flowers, an old term used to signify all those bodies that have received a pulverulent form by sublima- tion. Filiates, compounds of the salifiable bases with fluoric acid. Fluidity, the state of bodies when their parts are very readily moveable in all directions with respect to each other Fluoboratcs, compounds of the fluoboric acid with the salifiable bases. j, Fluor, fluate of lime, or Derbyshire spar. Fluorine, the radicle of the fluoric acid. ' 33* 390 INTRODUCTION Flux, a substance, or mixture added to assist the fusion of metals. Formiatcs, compounds ofthe formic acid with saliftablo bases. Fuligenous. Vapours which possess the quantity of smoke. Fulmination. Thundering or explosion with noise. Fungates, compounds of the fungic acid with salifiable bases. Fungin, a substance obtained from mushrooms. Fusibility, that property by which bodies attain the fluid state. Fusion, the act of fusion; also the state of a fused body. G. Galena, the black ore of lead. Gall of animals. Bile. Gallates. Salts formed by the combination of any base with gallic acid. Galls, the protuberances formed by the puncture of an insect on plants and trees of different kinds. Galvanism, the chemical action of bodies on each other. It is a method of exciting electricity or disturbing the equilibrium of the electrical fluid. Gamboge, a concrete vegetable juice, partly of a gum- my and partly of a resinous nature. Gangue, the stones which fill the cavities, that form the veins of metals, are called the gangue, or matrix of the ore. Gas, a name given to all permanently elastic fluids, simple or compound, except the atmosphere, to which term air is appropriated. Gelatine, a chemical term for animal jelly. TO CHEMISTRY. 391 Geology, a description of the structure of the earth. Glauber's salt. Sulphate of soda. Giintmer, a name occasionally applied to micacious earths. Glucina, one of the ten substances known by the name of earths. Gluten, a vegetable substance some what similar to ani- mal gelatine. Gold, the most precious of all metals, of a yellow col- our, specific gravity 19.3. Goulard's Extract, a saturated solution of subacetate oflead. Granulation, the operation of pouring a melted metal into water, in order to divide it into small particles for chemical purposes Gravity, that property by which bodies move towards" each other in proportion to their respective quantities of matter. Gum, the mucilage of vegetables. Gum Elastic. Caoutchouc. Gunfiowder, a substance well known, it consists of 75 parts by weight of nitre, 16 of charcoal and 8 of sulphur, intimately mixed together. H, Heat. Caloric. Hematin, the colouring principle of logwood. Ile/iar Sulfihuris, a name given tc* alkaline and earthy sulphurets, from their liver brown colour. Hefialic gas, an old name for sulphuretted hydro- gen. Hermetically, a term applied to the closing of the 392 INTRODUCTION orifice of a glass tube, so as to render it air tight. Hydrogen, one of the constituent parts of water. Hydrocarbonates, combinations of carbon with hydro- gen. Ilyfieroxygenizrd, a term formerly applied to substan- ces which are charged with the largest quantity of oxy- gen. J. &I. Jargon, see zircon. Icihyocolla. Fish glue, or isinglass. Ice. The natural state of water, or water in its crystallized form. Incineration, the burning of vegetables for their ashes. Indigo, a blue colouring matter, extracted from a plant called Ami. Indigo-gene, the colouring principle of indigo. Ink, a liquid used for writing or printing. Insolation, a term sometimes used to denote that expo- sure to the sun, which is made in order to promote the chemical union of one substance with another. Intermediates, a term used when speaking of chemica affinity. Iodine, an undecompounded principle. Irridium, a metal found in the ore of platinum. Iron, a metal well known, of a bluish white colour, of considerable hardness and elasticity. Isinglass, ichthyocolla, almost entirely composed of gelatine; TO CHEMISTRY. 393 K. Kali, a genus of marine plants, which is burnt to pro- cure mineral alkali, by lixiviating the ashes. Kaolin, the Chinese name for porcelain clay. L. Laboratory, a place fitted up for the performance of chemical operations. Lactates, compounds of lactic acid with salifiable ba- ses. Lacquer, solution of lac in alcohol. Lake, a species of colour formed by precipitating col- ouring matter with some earth or oxide. Lead, a white metal of a bluish tinge, very soft and flexible, not very tenacious, and incapable of being drawn into fine wire, though it is easily extended into thin plates. Lens, a glass convex on both sides for concentrating the rays of the sun. Levigaiion, the mechanical process of grinding the parts of bodies to a fine paste, by rubbing the flat face of a stone, called a muller, upon a table or slate, called the stone. Lime, oxide of calcium, one ofthe primitive earths. Liquefaction, the change of a solid to the state of a fluid, by the absorption of caloric. Lithia, a new alkali, discovered by Arfredson, in the laboratory of Berzelius. Lixiviati'jn, the application of water to the fixed resi- dues of bodies, for the purpose of extracting the saline part. Lixivium, a solution obtained by lixiviation. Lunar Caustic. Nitrate of silver. > 394 INTRODUCTION Lute, a chemical term, used to express the cement for joining of broken vessels, or two vessels together. M. Maceration, the steeping of a body in cold liquor. Magistery, a term originally applied to precipitates. Magnesia, one of the primitive.earths, possessed of a metallic basis, called magnesium. Malates, salts formed by the composition of malic acid with a salifiable basis. Malleability, the power of being extended under the hammer. Maltha. Mineral tallow. Manganese, a metal of a dull whitish colour when broken, but which soon grows dark by oxidation, from the action ofthe air. Manures, animal and vegetable matters introduced in- to the soil, to accelerate vegetation, and increase the production of crops. Marble. Carbonate of lime. Massicot, yellow oxide, or the deutoxide of lead. Matrix, the earthy or strong matters which accompany ores, or surround them in the earth. Mellaies, compounds of the mellitic acid with salifiable bases. Mefihitic gas. Carbonic acid. Menstruum, a word synonymous with solvent. Metallic oxides, metals combined with oxygen. Minium, the red oxide of lead, commonly called red lead. Mordants, substances which have a chemical affinity for vegetable colours. Mother iVa'rrs, or Mothers the liquors which are left after the crystallization of any salt. TO CHEMISTRY. 395 Mucites, salts formed by the combination of any base with the mucous acid. Mucus, one of the primary animal fluids, perfectly dis- tinct from gelatine. Muffle, a small earthen oven, to be fixed in a furnace for the purpose of cupeliation. Must, the juice of grapes, composed of water, sugar, jelly, gluten, and bitartrate of potash. Myricin, the ingredient of wax which remains after >digestion in alcohol. N.. Naphtha, a native combustible liquid, of a yellowish white colour, perfectly fluid and shining. Naples yellow, lead calcined with antimony and potash. Natron, native carbonate of soda. Neutralization. When acid and alkaline substances are added together in such proportions that the compound does not change the colour of litmus or violets, they are said to be neutralized. Nickel, a metal of great hardness, of uniform texture and colour, between silver and tin, it is said to be mag- -netical. Nicotin, a peculiar principle obtained from tobacco. Nitrates, compounds of the nitric acid with the salifia- ble bases. Nitre, one ofthe names of nitrate of potash. Nitrogen, or azote, an important elementary or unde- compounded principle. It constitutes four fifths of the volume of atmospheric air. o. Oil of vitriol. Sulphuric acid. Olefiant gas. Carburetted hydrogen. 396 INTRODUCTION Opacity, the faculty of obstructing the passages Di light. Ores. Bodies from which metals are extracted. Orpiment. Sulphuret of arsenic. Osmium, a metal discovered in the ore of platinum. Oxalates, compounds of oxalic acid with salifiable bases. Oxidation, the process of converting metals, or other substances into oxides, by combining with them a certain portion of oxygen-.' Oxides, substances combined with oxygen, without be- ing in the state of an acid. Oxygen gas. Vital air.' Oxymuriatic acid. Chlorine. Oxyprussic acid. Chloro-prussic acid. P. Paste, glass made in imitation of gems. Pellicle, a thin skin which forms on the surface of sa- line solutions and other liquors, when boiled down to a certain strength. Phosphates, salts formed by the combination of any base with the phosphoric acid. Phosphorus of Baldwin. Ignited muriate of lime.' Phosphorus of Canton. Oyster shells calcined with sul- phur. Phosphorus of Bologna. Sulphate of barytes. Phosphuret, a compound of phosphorus with a combus- tible, or metallic Oxide. PhlogisticaUd acid. Nitrogen. Phlogisticated alkali. Ferroprussiate of potash. Phlogiston, inflammable principle of the old chemists Picromel, the characteristic principle of bile. Picrotoxia, the bitter and poisonous principle of coccw- lus indicus. Pinchbeck, an alloy of copper. TO CHEMISTRY. 397 Platina, one of the metals. Plumbago. Carburet of iron—black lead. Pneumatic. Any thing relating to the airs and gases. Pot tsh, the hydrated deutoxide of potassium. Potassium, the metallic base of potash. Potential cautery. Caustic potash. Prussiales, combinations of prussic acid with salifiable bases. Prussine, prussic gas, or cyanogen. The base of the prussic acid. Pyrites, native metallic sulphurets. Pyrometer, an instrument for measuring very high tem- peratures. Pyrophorus, a compound substance, which heats of it- self, and takes fire on the admission of atmospheric air. Q. Quartation, is an operation by which the quantity of one thing is made equal to a fourth part of a quantity of another. Quartz, a name given to a variety of silicious earths, mixed with a small portion of lime or alumina, and gen- erally containing some metallic oxide. Quercitron. The bark ofthe yellow oak. Quicksilver. Mercury. R. Radical, that which is considered as the distinfuishino- part of an acid, by its union with the acidifying princi- ple, which is common to all acids. Rancidity, the change which oils undergo by exposure to the air. Re-agents, certain bodies used for detecting principles in solution. 31 398 INTRODUCTION Realgar. Sulphuret of arsenic. Receivers, chemical vessels, which are adapted to the necks or beaks of retorts, into which the liquid when distilled is received. Reduction, or Revivification, the restoration of any sub- stance to its natural state, or which is considered as such ; it is usually applied to operations by which metals are restored to their natural «tate. Refrigeration. The act of cooling. Rcgulus, a term applied to metallic substances when separated from others by fusion. Respiration, a. function of animals, which consists in the alternate inhalation of a portion of air into an organ cr.l- led the lungs, and its subsequent exhalation. Retort, a vessel employed for many distillations, and most frequently for those which require a degree of heat superior to that of boiling water. Rhodium, a metal discovered among the grains of crude platinum. Rochelle salt. Tartrate of potash and soda. s. Sal Ammoniac. Muriate of ammonia. Sal Catharticus Amarus. Sulphate of magnesia Sal Diureticus. Acetate of potash. SalGlauberi. Sulphate of soda. S%tl Martis. Green sulphate of iron. Sal Polychrest. Sulphate of potash. Salifiable Bases, the alkalies and those earths, and me- talic oxides, which have the power of neutralizing acidity, entirely or in part, and producing salts. Salt, the union of an acid with an alkali, earth, or me talic ox in.*. TO CHEMISTRY. 399" Sanguification, that process of the animal economy by which chyle is converted into blood. Saponaceous, p-.rtaking ofthe nature of soap. Saturation. When a fluid holds as much of one sub- stance in solution as it can dissolve, it is said to be satu- rated. Selenium, a new elementary body, discovered by Ber- zelius, which he ranks between sulphur and tellurium. Sebat, a neutral compound of'sebacic acid, with a base. Silica, one of the primitive earths. Silicon, the base of silica. Silver, the whitest of all metals, harder than gold, ve- ry ductile and malleable. Silvering, the art of covering metals and some other substances with a coating of silver. Soda. Mineral alkali. Sodium. The base of soda. Solder, an alloy used for uniting metallic bodies to- gether. Sorbates, compounds of sorbic acid, or malic, with the salifiable base . Spelter, the commercial name for zinc. Starch, a white insipid combustible substance, insolu- ble in cold water, but forming a jelly with boiling water. Steatites, a mineral, composed of iron, silex and mag- nesia. Steel, a carburet of iron. Strontia, one of the substances usually called earthe. Strontium. The metallic base of strontia. Strychnia, a vegetable alkali found in the strychnus nux vomica. Suber. Cork. Sublimation, a process by which volatile substances are raised by heat and again condensed in a solid form. '400 INTRODUCTION Subsalt, a salt having an excess of base beyond what is necessary for saturating the acid ; as svpersalt is one with an excc?s of acid, the term bi is now more generally used. Succinates, compounds of succinic acid with a salifiable basis. Sugar of lead. Acetate of lead. Sulphates, definite compounds of sulphuric acid with the salifiable bases. Sulphites, definite compounds of sulphurous acid with the bases. Sulphuretted, combined with sulphur, T. Tannin, one ofthe immediate principles of vegetables, so called, from its use in tanning leather ; which is ef- fected hy its characteristic property, that of forming with gelatine a tough insoluble matter. Tanning, the art of manufacturing skins into leather. Tantalium, one of the names of a metal commonly cal- led columbium. Tarras, or Terras, a volcanic earth used as a cement. Tartar, a substance deposited on the inside of casks during the fermentation of wine. Tartrate, a neutral compound of the tartaric acid with a base. Tellurium, a name given to a metal of a tin white col- our, verging to lead-grey, with a high metalic lustre ; found in Transylvania. Telluretted hydyrogen, a gas formed by a combination of tellurium and hydrogen. Temperature, a definite term of sensible heat as mea- sured by the thermometer. Term Japonica. Catechu. TO CHEMISTRY. 40 i Thermometer, an instrument for measuring heat, found- ed on the principle, that the expansions of matter are proportional to the augmentation of temperature. Thorina, an earth, discovered in 1816, by Eerzelius, of Sweden. Thorinum, the supposed metalic basis of thorina, not hitherto extracted. Tin, a metal of a yellowish white colour, considerably harder than lead, scarcely at all sonorous, very mallea- ble, though not very tenacious. Titanium, one ofthe metals. Tombac, a white alloy of copper with arsenic, some- times called white copper; Touch stone, a variety of flinty slate. Tritorium, a vessel used for the separating of two flu- ids, which are of different densities. Trituration, a chemical operation whereby substances are disunited by friction. Tube of Safety, a tube open at both ends, inserted into a receiver, the upper end communicating with the ex- ternal air, and the lower being immersed in water. It is to prevent injury from too sudden condensation, or rarefaction, taking place during an operation. Tungsten, the name of a metal. Tungstates, salts formed by the combination of tungsti: acid with salifiable bases. Turbeth Mineral, sub deutosulphate of mercury. U. Ulmin, a substance exuding from the trunk of a species of elm, the ulmus nigra. Uranium. The name of a metal. Urates, compounds of the uric or lithic acid with any base. 31* 102 i.yiroduc:k).> Urea, a substance prepared from urine, Usudation, the roasting of ores to separate the arse- nic, sulphur, and whatever else is of a volatile nature, that is connected with and mineralizes the metal. When the matter which flies off is preserved, the process i* called sublimation, but when this matter is neglected, the process is called ustulation. V. Veratria, a new vegetable alkali, discovered in the veratrum album, white hellebore, and some other plants. Verdigris. Crude acetate of copper. Verditer, a blue pigment, obtained by adding chalk ©r whiting to a solution of copper in aqua fortis. Vermillion. The red sulphuret of mercury. Vinegar. Acetous acid. Vinegar from wood. Pyroligneous acid. Vital Air. Oxygen. Vitrification. When certain mixtures of solid substan- ces are exposed to an intense heat, so aa to be fused and become glass, they are said to have undergone vitrifica- tion. Volatili'y, a property of some bodies which disposes them to assume the gaseous state. w. Wash, the technical term for the fermented liquor, of whatever kind, from which spirit is intended to be dis- tilled. ' Wax. an oily concrete matter, gathered by bees from plants. Way, dry, a term used by chemical writers when treat- ing of analysis or decomposition, TO CHEMISTRY. 405 Way, humid, a term used in the same manner as the above, hut expressive of decomposition in a fluici state. Whiting. Chalk cleared of its grosser impurities. Wodunium, the name of a recently discovered metal. Y. Yttria, a name of one of the earths. z. Zaffre, the residuum of cobalt, after the sulphur, ar senic,and other volatile matters of the mineral have been expelled by calcination. Zero, the commencement of the scale of a thermome- ter marked 0. Thus we sa}r, the zero of Farenheit, which is 32° below the melting point of ice, the zero of the centigrade scale which coincides with the freezing of water. The absolute zero is the imaginary point in the scale of temperature, when the whole heat is ex- hausted, the term of absolute cold, or privation of ca- loric ; this has never been ascertained. Zimome, the gluten of wheat, treated by alcohol, it is reduced to the third part of its bulk. Zinc, a metal of a bluish white colour, somewhat light- er than lead. Zircon, an earth found in the jargon of Ceylon. Zumates, combinations of the zumic acid with the sali- fiable bases. INDEX. A. Aceric acidr . 192;- Acetic acid, - id. Acidifiable metals, . . 237 Acids, 157 rli-'^inr'itinn rxf 159 ----of organic origin,. 192 Aconita, . * 303 Affinity, 11 Aggregate, 12 Aggregation, . it. Albumen, 300 347 Alcohol, >. 31-2 316 Alcohol of sulphur, 95 Alkalies, . 111 mi^f ir itv of, 112 ------fixed, ib. vnl'itilp ib. Alumina, 147 Amber, 325 Amianthus, 147 Ammonia, . 119 Amniotic acid, 193 Animal heat, 371 Animal products, 345 Animalization, 343 Antimonious acid, 182 Antimonic acid, 183 406 INDEX. Antimony, ^. Aphlagistic lamp, 320 Aqua Fortis, 82 Arrack, 311 Arsenic, 273 Arsenic acid, 181 Arsenious, 367 Arteries, 367 Asparagin, . 299 Asphaltum, . 334 Atomic theory, 21 Atoms, 22 Attraction, 6 Atropia, 303 Azote, 11 Balsams, -..,.. 301 Barium, . . . . .138 Barytes, . . . .136 Benzoic acid, . . _ 193 Bile, . 360 Bird lime, . 30] Bismuth, . . , . # 266 Bitter principle, .... 300 Bitumens, ..... 324 Black lead, ..... 256 Blood, , 349 356 Blow pipe, . . . 89 Boiling, ..... 05 Boletic acid, . , . . .193 Bones, ..... 354 Boracic acid, .... 162 INDEX. 407 361 313 254 321 149 303 274 267 G. Cadmium, ., -% • 26 £ Caloric, 43 57 69 Calorific rays, . 42 Camphor, . 301 Camphoric acid, . . - 194 Caoutchouc, . 302 Capacity for heat, . 69 Carbon, 11 103 Carbonates, . 164 Carbonic acid, . 105 106 162 Carburetted hydrogen, . 88 107 Caseic acid, . 194 369 Caseous matter, -. 348 Causticity of alkalies, 112 Cements, . 142 Cerium, , 282 Chalk, 140 Chameleon mineral, , . 270- Charcoal, • 103 Cheese, . 369 Chemical attraction, . 13 Chemical equivalents, . 233 Chemistry, > ) Brarn, Brandy, Brass, Bread, Bricks, Brucia, Butter of arsenic, -----of bismuth. ,i.08 1KM3t- Chest, 366 Chloric acid, - 167 Chloric oxide, 211 Chloride of sulphur, 94 Chlorine, 205 Chloro carboneous acid, .. - ' 169 Chloro prussic acid, - 189 Chromic acid, - - 183 Chromium, ... 275 Cicuta, - ... 303 Citric acid, - - - - - 194 Coal, 325 Cobalt, - - 270 Cocheneal, - 307 Cohesion, - 6 Coke, 325 Cold, 50 Colorific rays, .... 42 Colouring matter, 306 of the HnAd 369 Columbic acid, - 184 Columbium, - 287 Combined caloric, - 44 61 69 Combustion of sulphur, 92 Conductors of caloric, - 57 Copper, - 2P\ Cotton, - 302' Crawford's theory of animal heat, - 372 Crystallization, - 6 ------of metals, 233 Cyanogen, - 284 INDEX. 409 D. Datura,..... 306 Decomposition, 14 ------of alkalies, 123 ------of vegetables, 309 84 107 303 Delphinia, - Deoxydizing rays, 42 Dew, - - 64 Diamond, - 104 Diaphragm, ? 366 Diana's tree, - 245 Differential thermometer, 48 Digestion, (Pepins) 66 Digestion, - 344 Divisibility of matter, 2 Division of substances, - 9 Dry rot, .... 322 Dyeing, .... 307 E. Earthern ware, ......149 Earths,........133 ----found in plants, - - - - 131 Elastic fluids, .... 49 Electricity, ..... 220 Electric attraction, - - 7 Elements, - - - . 10 Epidermis, - - - - - !354 Ether, - - - - - 318 Euchlorine, - - - 210 35 410 INDEX. Evaporation, ... - 45 Exp.insion of bodies, - - - 4T> Extractive matter, .... 300 F. Fermentation, .... 309 Ferroprussic acid, - - - - 188 Fixed air, - - - - - 105 ----alkalies, . . . 112 ----oils, ..... 301 Flame. ..... 87 Flowers of antimony, - - - - 182 Flowers of bismuth, - - 266 -------of sulphur, ... 91 -------of zinc, - - - - 262 Fluate of lime, - - - - 12 186 Fluoboric acid, . - >• 190 Fluoric acid, - . - - 186 Fluosilicic acid, - - - 154 190 Freezing, - - - - 61 65 ------- of lakes, - 62 Fuller's earth, - - - - 154 Fungic acid, .... - 191 Fungin, ... 302 Fusion of metals, 63 G. Galena, - - - 261 Gallic acid, - - , - 195 Galvmism, - - - 224 Gaslights, - - .88 Gas:r.c juice, * ' - 362 Gelatine, - - - 345 346 INDEX. 411 Germination, - 333 Gin, . 314 Glass, - 115 ----of antimony, - 268 Glazing, - 149 Glucina, - 151 Glue, . 316 Gluten, - 300 Gold. - 241 Goulard's extract, . 261 Gravitation, . 6 Guaiacum, . 301 Gum, - 299 Gypsum, - 14 H. . ^ Hartshorn, - - - - 120 Heat, - - - 44 ----of capacity, - - 70 ----latent, - - - 69 71 Heart, - - 307 Heat of the human body, . . 372 Hematin, - 302 Hydrate of potash, - - - 113 Hj'driodic acid, - - . 137 Hydrogen, - - . - 83 --------gas, combustion of - - - 86 ---■----- how obtained, - - - 84 --------acids, - lyg Hydroguretted sulphuret of ammonia, - 120 Hydrochlorides, - - . - 167 Hydrosulphurous acid, - - - 188 Hyosciama, ... . 304 Hypophosphorous acid, - - - 171 412 INDEX. Hyposulphurous acid, Hyposulphuric acid, I. Ignition, Impenetrability, Indigo, Ink, - Instruments for measuring heat, Inulin, ... ■iodic acid, Iodides, Iodine, Iridium, ... Iron, - -----cold short, • - -----protoxide of - Iron mould, Isinglass, J. James' powder, Jelly, Jet, K. Kermes mineral, Kinic acid, L. Laccic acid, Lactic acid, - ■*• INDEX. 413 Lakes, freezing of . . 62 Lampic acid, - - 196 , Lapis calaminaris, - - 262 Law of Berzelius, - - 18 **r e? i^Vv4/->»-> or. Laws of affinity, ., _ ~0 16 Lead, - ■ 259 Leather, - 316 334 Light, - - 38 Lime, - - 139 Lime water, - - 140 Liquor of Libavius, - - 206 Litharge, " - 259 Lithia, - - 117 Lithic acid, - - 196 Liver of sulphur, - - 115 Luna cornea, - - 243 Lunar caustic, - - 244 Lungs, .- • 366 ' M. Majestery of bismuth, Magnesia, Magnesium, Magnetic attraction, Manganese, Margaric acid, Malic acid, Manure, Matter, Meronic acid, Medulla oMnngata, - Mf-Lwic acid, 35* 267 145 147 7 - 267 197 ib. 323 1 197 362 197 414 INDEX Mellitic acid, ... - - - 108 Mercury, ... . . . 217 Menispermicacid, - - 197 Metallic acids, - - 181 Metals, ..... 235 Mineral tar, . 325 ------pitch, . ibid Mixtures, . . .12 Mobility, . . . 3 Molybdenum, - - - - 276 Molybdic acid, - - - 184 Molybdous acid, ... ibid Momentum, ... 6 ;Mordants, ... 308 Moroxylic acid, - 198 Morphia, .... 304 Motion, ..... 4 Mucic acid, - - - 198 Mucus, - 350 Muriates, - - - - - 167 ------ of ammonia, - - - 120 Muscles, .... 353 N. Naptha, Neutral salts, Nickel, Nitrate of potash, Nitric acid, Nitrogen, ------properties of ------uses of Nitrous acid, 329 112 261 46 80 81 80 169 INDEX. 415 o. Oils, Oleic acid, Organised bodies, Orpiment, Osmazome, Osmium, Oxalic acid, -t Oxides, Oxygen, ------properties of Oxygen acids, Oxyhydrogen blow pipe, Oxymuriatic acid, Palladium,...... Parenchyma, ..... Particles of light, ... Peat, - Perchloric acid, Petroleum, - Pewter, j Phosgene gas, - - Phosphorescent, ... Phosphoric acid, Phosphorous acid, ... Phosphuretted hydrogen, Phosphorus, - . . jj ---------combustion of Picromel, .... Picrotoxia, Platinum, . . . „ 108 - 198 297 - 274 351 - 278 199 77 78 - 74 75 181 - 89 " 205 246 332 - 39 135 326 168 325 267 169 40 98 172 99 171 - 89 97 101 98 100 351 304 238 416 INDEX. Plaister of Paris, - - - M Plumbago, - - - 108 2.>6 Plumula, - - - - 33 j Pollenin, - - . 303 Porcelain, - - - 149 Potash, - - - - - 113 Potassium, - - - 121 Potential cautery, - - 2 - 1M Pot metal, - - - 254 Principles of radiation, - - 35 Prussian blue, - - - 178 352 Prussic acid, - - - 177 Prussine, .... 284 Puzzollano, - - . - 143 Pyroligneous acid, - - - 193 321 Pyrolithic acid, .... 200 Pyromalic acid, . . . , ibid Pyrotartaric acid, .... ibid Q- Quicksilver, ...... 247 R. Radiation,.......50 -------principles of 53 Rays of light, .... 39 Realgar, ..... 274 Refrigerators, . . . .108 Regulus of antimony, . . 268 Resin, ...... 301 Respiration, . . . . 365 Rhodium, . , . .280 Rock crystal, ... 153 INDEX. Rosacic acid, Rum, s. Sal ammoniac, Salt of tartar, Salt petre, Salts, Sarcocol, Saturation, Sebacic acid, Selenium, Selenic acid, Silica, Silver, Size, . .346 Skin, . ... 354 Slacked lime, • . . .161 Soda, . . .116 Sodium, . . . 129 Solidity, . . . . . 2 Sorbic acid, . . . . 201 Sources of light, .... 43 Specific caloric, 70 Speculum metal, - 254 Starch, 299 Steel, ..... 108 Strontian, ..... 138 Strychnia, ..... 304 Suber, - - - - - - 302 Suberic acid, .... 201 Substance, ..... 1 Succinic acid, ... 202 41f 201 314 114 116 211 299 217 201 277 278 152 184 INDEX. Sugar, -.......299 ----of diabetes, - . - 352 ----of lead/ - - - 260 ----of milk, ... ;; I I Sulphate of lime, - . - - 14 Sulpho cyanic acid, - - 94 Sulpho vinic acid, - - 202 Sulphur, - - - - 91 ------combination of 3 92 -------combustion of ibid -------uses of 96 Sulphurets, ... .93 Sulphuret of potash, . .115 Sulphuretted hydrogen, 89 Sulphuretted chyazic acid, 94 Sulphuric acid, . .174 Sulphurous acid, . . 173 Super saturation, . . 217 Sympathetic ink, .271 T. Talc,.....149 Tallow, . . .108 Tannin, . . 301 Tantalium, , .277 Tarras, . . . .143 Tartar emetic, . .269 Tartaric acid, ... 202 Tellurium, . . .271 Telluretted hydrogen, . . i°id Thermometer, ... 46 Theory of caloric, .50 Thorina, . .15' INDEX. 419 Tin, . . ... 257 ----foil, ..... ib. Titanium, . . .282 Triple salts, . . . . .217 Tungsten, . . . . .276 Tungstic acid, . ,. . . 184 Turf, . • , . 135 326 u. Ulmin,....... '299 Uncombined caloric, ..... 49 Uranium, . . . . .281 Urea, ..... 350 Urine, . . - .357 V. Vaporization, 64 Vegetables, 297 Vegetation, . 328 Veins, . 367 Velocity, 5 Veratria, . 304 Verdigris, 253 Vinegar, . 320 Volatile alkali, 112 119 ------oils, 301 Volumes, 27 Voitaism, 224 w. Water, freezing of .62 Wax, 108 301 420 INDEX. Whiskey, ..... 364 White lead, . . . . .259 White vitriol, . . . 263 Wodanium, . . . 283 Wood, . . . 302 Yttria, .......... 151 z. Zinc,........262 • Zirconia,....... 152 Zumic acid, ...,'• .202 ■v£&&&