f^^mmmmmi r must ever be counted as one of the most valuable contributions which Berzelius has made to chemistry. Law of The truth of Dalton's Atomic Theory w^as also borne out by the discovery, made in 1805, by Alexander von Hum- boldt and by Gay-Lussac, that two volumes of hydrogen combine with one volume of oxygen to form water. This ultimately led to the determination of the law which governs the volume com- bination of gases, the so-called Law of Volumes, announced by Gay-Lussac in 1808. This law holds that the ratio in w^hich gases combine by volume is always a simple one, and that the volume of the resulting gaseous product bears a simple ratio to the volumes of its constituents. Dalton at first took issue with Gay- Lussac's statements and reasoning, for the latter made no distinction between atoms and atom-complexes, now termed 58 molecules. But in 1811 an Italian phy- Avoga- sicist, Amadeo Avogadro, succeeded in Hypo- showing, by establishing a difference be- thesis tween molecules integrantes and molecules eleme7ttaires, integral and elementary molecules, that the observations of Gay- Lussac and the teachings of Dalton were in full accord. Our term molecules cor- responds to the first of these conceptions, our term atoms to the second. Mole- cules are regarded as composed of indi- visible atoms. Avogadro was the first to demonstrate that equal volumes of all gases contain an equal number of mole- cules. Ampere's name is often linked with Avogadro' s theory, but the essay of the former did not appear until three years after Avogadro had made his announcement. Yet it was only in 1858, through Cannizzarro's able presentation of Avogadro' s work, that the latter re- ceived the recognition which it so justly deserved. An hypothesis was advanced in 1815 Prout's by an English physician, Dr. Prout, to J^gg^s' the effect that the atomic weights of all elements are whole numbers and that the elements themselves are condensa- tion-products of hydrogen. 59 While the claim that the atomic- weights are simple multiples of the atomic weight of hydrogen, has long aga been completely disproven by exact analytical determinations, yet it must not be overlooked that Front's claims gave the impetus to many most valuable in- vestigations which have been carried out with the utmost refinement of analytical skill. It is through such most accurate determinations of some of Nature's con- stants, that chemistry has justly gained the distinction of ranking as one of the exact sciences. Law of In 1 819, Dulong and Petit discovered and Pet^ the fact, that the specific heat of an element is inversely proportional to its atomic weight, or, as they expressed it, that the atoms of the different elements have the same capacity for heat. Specific heat is defined as the ratio of the amount of heat required to raise a given weight of a body one degree in temperature, compared to the amount of heat required to raise the same weight of water to the same extent. As the average value of the product of the specific heat of an element by its atomic weight is about 6.4, a simple division of this constant by the specific heat of the 60 •element in the solid state, gives approx- imately the weight of an atom of that element, thus affording valuable indica- tions in determining these very import- ant values, the atomic weights. Mitscherlich's theory of isomorphism, Isomor- that compounds of analogous composi- P ^^^ tion and containing the same number of atoms assume the same form in crystal- lizing, was, b}^ Berzelius, considered to be of value in the determination of atomic weights. Time, however, has proven that the results which this theory has yielded are deserving of less credit and credence than was once accorded them. Experiment having conclusively shown Chem- that in numerous instances substitu- Equita- tion of one element for another could be lents and effected, the relative amounts of the different elements which could thus re- place each other naturally called for consideration. The term equivalent was applied to the smallest amount b}^ weight of an element which could combine with or replace the unit weight of hydrogen. The weight of an atom, the atomic weight of an element, must then be iden- tical with or must be some multiple of this value. For a tune considerable confusion 6r i reigned in this question of atomic weights and chemical equivalents, until, chiefly through the researches of Edward Frankland on the organo-metallic sub- stances, the idea of valence was intro- duced. The terms valence, valency, or quanti- valence designate the degree of combin- ing power of an atom of any element, compared with the combining power of an atom of hydrogen selected as unity. According to the degree of the combin- ing power thus defined, the elements are classed as monads, dyads, triads, etc. This means that one atom of an element can combine with or replace one, two, three or more atoms of hydrogen, as the case may be. The relation betw^een the chemical equivalent and the atomic weight of an element is expressed by the formula : the atomic weight of an element is equal to the product of its chemical equivalent by its valence. Thus, in the case of monads, atomic w^eight and chemical equivalent are identical; in dyads, the atomic weight is equal to twice, in triads it is equal to three times the chemical equivalent of the element. The importance of exact determina- 62 tion of the atomic weight values of the Atomic elements will be appreciated, when it is Weights remembered that these values may be regarded as the constellations by which the courses of chemistry are shaped. One of the most eminent chemists who ever engaged in the determination of atomic weights was Jean Servais Stas, a Belgian. He was a pupil of Dumas ; his results, based on experiments made with larger quantities of material than are usually employed in such determinations, furnished much of the evidence that dis- proved the hypothesis of Prout. Among American chemists who have achieved especial distinction in work along these lines, there should be men- tioned Morley, Clarke and Richards. Since 1893 ^^ American Committee on Atomic Weights has issued, — through the pen of F. W. Clarke, — annual reports on these values. The table of Atomic Weights given Table of on page 65 has been recommended for ^°?"\^^ general adoption in analytical practice by a commission consisting of H. Landolt, W. Ostwald and K. Seubert. This representative commission was appointed by the German Chemical Society. 63 Its members recommend that : 1. The atomic weight of oxygen be taken as 16.000, and that the atomic weights of the other elements be calcu- lated on the basis of their combining ratios with oxygen, directly or indirectly determined. 2. The following atomic weights of the elements be adopted in practice, as they are probably the most correct values known at the present time. (See table.) These numbers are, as a rule, given only with so many decimals that even the last one may be regarded as accurate. In consequence, the atomic weights de- termined by Stas, in which the errors amount to from 3 to 6 units in the third decimal, are given with two decimals ; the other atomic weights, which have been more accurately determined, are given with one decimal, and those less accurately determined are given without decimals. Exceptions to this rule have been made only in the cases of nickel, bismuth and tin, marked with an asterisk in the table. In the case of nickel this was done in order to emphasize the difference be- tween the atomic weights of cobalt and nickel, although in both values there 64 <^ 1-1 ic 1-t on ^- ^^ rH C^ Oi 1— t —'CVJ 1— t s lis .2 a £"51 ^s ^^S^;z;z;z;co^;i,2,p:p.;2^ ^ •X- E s -<* ^ :2 -^« ^1 ^s m-- zrl^ s 5^1 Ti ?^g 05 2 |Sgg2^g ;Ki:'J:^S:5 may be possible deviations of ± 0.2. The true atomic weights of bismuth and tin are not correct to a certainty, to within 0.1. The value of hydrogen is 1.008, correct to within o.ooi, but the approximation of i.oi has been regarded as permissible for the requirements of practice, as it involves an error of only one-fifth of one per cent. The values given for the elements marked in the table with interrogation points are not necessaril}^ exact within whole units of the atomic weights assigned. Chemistry has been exceptionally fa- vored in the last year or two by the discovery of new elements. A study of argon and helium, consti- tuents of our atmosphere, has led to the discovery of several other new element- ary substances. Thus, Ramsay and Tra- vers have recently isolated from liquefied argon three new bodies, krypton (hid- den), neon (new) and metargon. All of these are gases and occur in the earth's atmosphere in minute amounts; neon, for instance, only to the extent of about one part in forty thousand parts of air. There seems to be some doubt as to whether metargon is or is not an element ; it is said to have about the 66 same atomic weight as argon, but is pos- sessed of difiEerent properties. It is a solid at the temperature of liquid air. Quite recently another new gas has been added to those previously obtained from liquefied argon ; xenon is the name that lias been assigned to it. In July, 1898, Professor Nasini of Padua announced that he had, while studying the gases emanating from the Solfatara di Pozzuoli and the fumarole of Vesuvius, discovered a new gaseous element. Coronium is the name given to this substance, now first found upon our earth, but which, on the evidence of the spectroscope, has for some time been known to exist in the corona of the sun. At the meeting of the American Asso- ciation for the Advancement of Science, in 1898, Charles F. Brush announced the finding of a new gas, which he had extracted from glass at low pressures. This new body is said to occur in the air and to be easily absorbed by numerous substances, especially by glass. On ac- count of its peculiar properties — its high molecular velocity, 105 miles per second, and its very low density, o.oooi if hydro- gen be taken as i.o — Brush suggested 67 that this might possibly be the ether, the existence of which is assumed in physics. The name which he proposed for this supposedly new element is, etherion. However, the possibility of this substance being water-vapor has been recently suggested by Sir William Crookes and further developments must be awaited before the question at issue can be deter- mined. The investigator last named has iso- lated from yttria a body to which he has given the name monium, from the Greek word for "alone." Its atomic weight will probably be about ii8 and it is said to enter readily into chemical combina- tion with other elements. Electro- Within the past century and a half ical chemistry has witnessed the birth and Theory the growth of a number of theories and hypotheses, which, while they have all exercised some influence, one way or an- other, on the development of our vScience, can here claim but a passing reference. Of these the first to call for attention is the electro-chemical theory of Berze- lius. Fundamentally this was based upon observations made by Sir Humphry Davy ; it held that every atom was en- dowed with certain amounts of both 68 positive and negative electricity. These electrical charges were supposed to be accumulated .on different parts of the atoms, giving rise to negative and posi- tive poles. It was the preponderance of the one or the other kind of electricity which, it was believed, determined the electrical character of an atom. Atoms electrijSed in an opposite sense would be attracted to, atoms bearing charges of the same kind would be repelled from one another. On the combination of atoms bearing unlike charges, neutraliza- tion of the same would result. Berzelius suggested the existence of Dual- compound atoms ; this view of the struc- \p^^ ture of matter came to be known as the dualistic theory. It was closely allied to the electro-chemical theory and is best considered in connection with the latter, which was, for almost twenty years, the dominant theory of chemistry. Reference, however brief, must be Fara- made of the important results secured by l^^-/ Michael Faraday in establishing the quantitative relations which obtain when electrical power is made to do chemical work. Faraday conceived the idea of sending an electric current successively through a series of cells which contained 69 different solutions which would permit the passing of electric currents. Such solutions are termed electrolytes, and his observations determined that an electric current of a given strength will set free equivalent quantities of the constituents of different electrolytes. His law of con- stant electrolytic action was enunciated in 1833 ; its discoverer believed that it would prove a valuable aid in the deter- mination of atomic weights. Attacks Dumas and other French chemists, on the ^T^ile ensrasred in studying: the atomic Atomic . . 7 , ^ . , Theory weights of the elements, were led, through their determinations of the spe- cific gravity of vapors at high tempera- tures, to seriously doubt the validity of the law of volumes. It chanced that Dumas worked chiefly upon substances the molecules of which were complex, a fact, however, unknown to the experimenter. Finally, and in consequence of his results, Dumas ques- tioned the truth of the law of Avogadro. Other evidence also seemed to point to the untenability of Avogadro' s conclu- sions, and Leopold Gmelin, a pupil of Berzelius, a most eminent chemist and the author of several important works on chemistry, was led to abandon the atomic 70 theory completely. Gmelin held that, as a rule, the proportions in which sub- stances could combine were unlimited in number. He issued a table of equiva- lents, which might be styled a list of combining numbers. When a choice of equivalents seemed permissible, the low- est value was selected. His views on these matters met with general favor and were incorporated in many text-books, even as late as thirty years ago. The theory of radicals can primarily Theory be traced to the writings of I^avoisier ; Radicals after passing through various modifica- tions it attained to prominence about the year 1838, having received its greatest impetus from an investigation under- taken in 1832, by Justus von I^iebig and by Wohler, " On the Radical of Benzoic Acid," which showed the existence of an atomic group — benzoyl — in oil of bit- ter almonds and its derivatives. As this theory, as well as the dualistic theory, involved the conception of atoms, both contributed to restore to favor Dalton's views, which had once been held in great esteem. An attempt to apply the theory of ^Ethertn radicals to organic compounds resulted ^^^'^ in the so-called *' ^therin " theory, 71 which was advanced by Dumas and Boullay, defiant gas, for which Berze- lius suggested the name " setherin," was regarded as a constituent of the alcohols, the sugars and other substances, these bodies being in their composition com- pared to the compounds of ammonia. Substi- Berzelius' theory of dualism was dis- tution pQsed of primarily through a research on wax-candles by Dumas, an investigation •in which the principle of substitution of chlorine for hydrogen was discovered and proven. Dumas further explained by his theory the formation of chloro- form and of chloral, w^hich bodies Liebig had obtained by the action of chlorine on alcohol. Nucleus Auguste Laurent, finding that Dumas' Theory ^^^^ ^£ substitution did not afford a valid interpretation of all the data observed, suggested his nucleus theory ; this was an outgrowth of the theory of radicals, but, instead of claiming the existence of atomic groups of stable and unchange- able composition, Laurent's views held that such groups admitted of changes by the substitution of equivalents. Unitary Notwithstanding the efforts of Berze- Theory ^.^^ ^^ uphold his dualistic theory, to achieve which he evolved the hypothesis 72 of conjugate compounds, and notwith- standing the labors of Kolbe, which were directed to the same end, Laurent and his friend Carl Gerhardt carried the day with their unitary theor3\ This latter maintained that the nature of a molecule was determined by the nature, the num- ber and the arrangement of the atoms which formed it, and furthermore, that these atoms were capable of being ex- changed for — that is, were capable of being replaced by — other atoms. Laurent and Gerhardt introduced the Theory theory of types. They originally recog- ^^yp^^ nized three types : water, ammonia and h^'drochloric acid, and in their classifica- tion the}^ sought to refer all compound substances to one or the other of these as model forms. The continued disco- very of new bodies, however, soon made the creation and adoption of other addi- tional types a necessity, and the type- theory ere long grew to be unwieldy and cumbersome. The first half of the nineteenth century The witnessed various attempts to trace rela- Periodic lions between the atomic weights of elements and some of their properties. Possibly the first instance of this kind which received general attention was 73 the work done by Dobereiner, who, in 1829, found that certain elements have atomic weights which are approximately the mean of the atomic weights of two other elements closely resembling them in their properties. Dobereiner also as- certained that groups of three could be formed of some elements whose atomic weights were almost the same and which exhibited close analogies in most of their properties. A systematic classification- of the elements, basing on the similarity of their properties, was an ardent wish of this investigator. But, of course, ere this could be accomplished, accurate de- terminations of the atomic weights of all elements were imperative. The periodic law, which holds that the properties of the elements are periodic functions of their atomic weights, was established chiefly through the labors of Newlands, Mendeleeff and Lothar Meyer. It seems that the first communication Newlands made on this subject was pub- lished early in 1863. In the following 3"ear he issued a list of the elements in the order of their atomic weights ; the announcement of the periodic law by the two other investigators named was made in 1869. 74 It is, however, the distinctive merit of Mendeleeff to have pointed out that the value of any given property of an element is practically an average of the values of the same property of two other elements w^hich immediately adjoin it, when the elements are arranged in a table progres- sively, in the order of their atomic weights. Moreover, this distinguished Russian chemist, from a close study of his tables illustrative of the periodic law, predicted the existence and the properties of cer- tain elements not then known. The discovery of Gallium, of Scandium and of Germanium, n^de respectively in 1875, 1879 and 1886, brilliantly fulfilled the prophecy of Mendeleeff. Neon, ''the new one," furnishes the most recent instance of an element sought for because the probability of its exist- ence seemed indicated by a gap in a periodic arrangement of the elements. It w^as discovered in and isolated from air by William Ramsay, the well-known. English chemist, whose name is also- linked with that of lyord Rayleigh in the. discovery of argon and of helium. An arrangement of the elements into groups and series, based on the principles. 75 indicated, and a close study of their rela- tions, have led, not only to a prediction of the existence of undiscovered elements, but have, in some cases, also proved of great value in the detection of erroneous atomic weights. The periodicity of many chemical and physical properties of the elements — for instance, of valence, of electro-chemical and magnetic powers, the toxic pro- perties of metals, and so forth — has re- ceived careful attention. Through studies of this kind it has become possible, in some instances, to predict the action of certain medical preparations, their com- position and molecular structure being known. A tracing out of such and similar rela- tions is certainly of great interest. Of recent years, experienced teachers of chemistry have found a presentation of the fundamental data of their science based on the periodic law, of great di- dactic value. While the periodic law, so called, cannot as yet give a logical ac- counting of all phenomena, it seems be- yond question that it is to-day one of the most important theories of chemistry. The valency of the element carbon had been studied and determined by Frank- 76 land. His conclusion that carbon is Stereo- Chem- tetra-valent was confirmed by the inde- pendent investigations of August Kekule, who, as a result of his researches into the manner of combination of carbon atoms mter se, laid the foundations of the important chain-theory, which has proved of great value in the realm of organic chemistry. Study of the structural arrangement of molecules, which resulted in the theory of the grouping of atoms in space, w^as initiated by the labors of Louis Pasteur, on the phenomena of isomerism exhibited by the tartaric acids. The work of Johnannes Wislicenus on lactic and sarcolactic acids, carried on in 1873, foreshadowed the teachings of Van't Hoff and Le Bel, who, in 1874, almost at the same time but independ- ently of one another, formulated the principles of stereo-chemistry. Van't Hoff had elaborated his ideas with the object of explaining the property which many carbon-compounds, when in solution, possess of rotating the plane of polarized light. Le Bel, who followed Van't Hofl's announcement w4th his own conclusions on the subject but a few months later, was likewise led to his 77 istry conceptions by a study of the optical behavior of certain solutions. A treatise by F. W. Clarke, Chemistry of Three Dimensions, published in 1875, likewise emphasizes the conclusion that all mole- cules must be tri-dimensional. Thus far the compounds of carbon and the compounds of nitrogen have received most attention from those who have given special care to the developments of stereochemistry, but chemistry in general has undoubtedly been enriched in many ways through the stimulation given by this new departure from the old and well beaten tracks. The Development of the language of chem- rua^e^of is^^y ^^^ ^^ course been conditioned by Chem- and kept pace with the evolution of the *^ ^ science. The earliest terms employed in chemistry were, as a rule, suggestive of the origin of the substances which they denoted. The term sal, for instance, was applied since the earliest times to all substances having a salty taste. About the eighth century the attempt was made to distinguish between different substances having a salty taste, by add- ing a word descriptive of the origin of such substance ; thus, common salt was called sal maris, salt of the sea. 78 The thirteenth century witnessed the free use of certain symbols to denote some of the metals ; thus, gold, called Sol by the alchemists, was by them de- picted by a circle with a dot in its center; silver, in their language Ltma^ was re- presented by a crescent ; copper, which they termed Verucs, was denoted by a circle to the bottom of which a small cross was attached. The original and true meaning of these symbols is not known ; many and fanciful, however, have been the explana- tions suggested. For instance, it has been supposed that the symbol chosen for Venus represented a hand-mirror. Some of the alchemists saw in these symbols an indication of the chemical properties of the metals they denoted. Thus, the circle was held to illustrate perfection of the metallic condition, the semi-circle an approximation to this state ; however, an attempt to trace the various signs which were gradually intro- duced into the science and the numerous transmutations which they suffered in the course of time, would carry us far beyond the purpose and the limit of these pages. Reference by name only can here be 79 made to the systems of symbols used by Geoffrey, by Bergman, by Dalton, hy Berzelius, by Hassenfratz and Adet. The last named was specifically in- tended to accompany the chemical no- menclature devised by Lavoisier, De Morveau and colleagues, the system which is the foundation of the one em- ployed at the present time. Within the past decade various at- tempts have been made to agree upon some method of chemical nomenclature and notation which should meet with universal acceptance. Concerning the names and the symbols of the elements, those known to the ancients mostly retain their original appellation. In naming elements the discovery of which belongs to a later date, it has become customary in the case of metals to assign the termina- tion 7im or tu?n to the name selected ; in the case of non-metals, to make the end- ing of the appellation tne, o?i or g-e?z. The choice of the name of an element rests, of course, with its discoverer. In some cases the names of the planets have been used for the purpose ; thus. Mercury, Tellurium, Selenium own as their spon- sors respectively Mercury, the earth and the moon. 80 In other instances the patriotism of the discoverer has immortaUzed the name of his country by bestowing the same upon the newly found substance. Columbium, Germanium and Gallium may be cited in illustration. The names of deities have also been pressed into service to this end; thus, Thorium from Thor, one of the gods of Norse mythology. Sometimes the name which an element bears has been suggested by some dis- tinctive property which it possesses. Iridium is derived from the Latin word iris, 2l rainbow ; Iodine from the Greek term for the violet ; Barium from the same language, from the word which denotes weighty. The names of chemical substances, of elements and of compounds, are fre- quently indicated by symbols. As a rule the symbols which denote the elements are indicative of their names and usually consist of the initial, or of the initial and some other letter of such name. Thus, carbon is designated by the letter C, cal- cium by the letters Ca, and copper by the letters Cu, these last being taken from the Latin appellation of copper, cupy^um. It is an important matter to remember 8i that the symbol of an element stands not only for its name, but represents at the same time a definite amount of the ele- ment — the weight of one atom. An atom is defined to be the smallest quantity of matter which can enter into chemical combination. If it be desired to indicate more than one atom, the requisite numeral is placed with the sym- bol. The symbols of compounds, usually termed formulae, are simply combinations of the symbols of the elements forming the compound and of numerals which indicate the number of atoms of the elements which are present in the com- pound ; thus, water is a compound of two gases, hydrogen and oxygen. The small- est amount of water, which can exist as such, contains two atoms of hydrogen and one atom of oxygen ; its formula- is therefore H^O. By a simple and ingenious system of terminals and of prefixes, taken in part from the lyatin and the Greek languages, chemists are enabled to have the name of a compound indicate to a certain ex- tent its chemical composition. The chemical composition of a com- pound can be concisely expressed in a formula ; from the chemical formula of a 82 substance, one versed in the language of chemistry can usually designate by name the substance represented. When elements or compounds aie sub- jected to influences which cause them to undergo changes, the reactions can be indicated by the aid of symbols and for- mulae. As matter is indestructible, nothing is lost in these reactions, and such expressions of change must there- fore, of necessit}', be equations ; they are termed chemical equations. Chemical equations are known respectively as syn- thetic, analytic, and metathetic, as they represent the formation of substances by the union, the decomposition, or the interchange of constituents. It was during the epoch of iatro-chem- Didactic istry that chemistry was first taught at jg^nT' the universities. At first the teaching of this subject was included in the lectures on medicine delivered by pro- fessors of that faculty. The first lecturer who treated chemistry as an independent subject was a German, Johann Hart- mann. He spoke at the high school at Marburg, in the first quarter of the seventeenth century. University instruction in laboratory practice was established much later, — in 83 fact, only towards the end of the centur3r last named ; the first public chemical laboratory for purposes of instruction was founded in 1683, b}^ the council of Nuremberg ; it was situate at Altorf , and its first director was Johann Moritz Hofmann. Lectures on chemistry, illustrated by experiments to serve didactic purposes, were introduced in France about one hundred 3'ears ago. In England, Sir Humphry Davy is credited with making this kind of instruction popular, and other CDuntries soon followed the novel practice. Modern methods of laboratory instruction in chemistry are generally believed to have been inaugurated by Justus von Liebig ; at least it is certain that his laboratory was one of the first to be established, and the same has certainly made its influence felt all over Germany and far beyond her borders. Manuals One of the earliest works on chemical ^ ist?y 'Subjects which can in any way be looked upon as a text-book, is an English pub- lication, Compoicnd of Alchyjnie, which was prepared by George Ripley, about the year 1471. In an introduction in verse, with which he prefaces his volume, he, after 84 informing his readers of his intentions, outlines the table of contents : *' But into Chapters thys Treatis I shall devyde, In numbre twelve, with dew recapytulatyon ; Superfluous rehearsalls I lay asyde, Indendyng only to give trew informatyon Both of the theoryke and practycall operatyon: That by my wrytyng who so wyll guyded be, Of hys intente perfyctly speed shall he.'* Agricola's work, De fe me tallica, pub- lished in 1546, contains a good i^esiune of the art of metallurgy as it was under- stood at that time, but the first general treatise on chemistry is probably the Alchy77iia, by Andreas Libau, or Libavius, as he was often called. This work, published in 1595, is divided into two sections ; the first of these describes chemical operations and apparatus and contains directions for the regulation and the application of fire. The second part of the book treats of the preparation and the properties of chemical substances and compounds. No consideration is given in this book to theoretical dis- cussions. Quite a number of works on chemistry were issued in the seventeenth century ; some of these laid special stress on medical chemistry, others were more 85 general in their character. Of these, pos- sibly the Coiirs de Chymie, published by Nicolaus Ivcmery in 1675, and the Chymia Philosophica, by Jacob Earner, which was issued in 1689, were the most important. The standard work of Hermann Boer- have, Elementa Chemiae, first published in 1732, consists of two parts, the first of which deals with the theory, the second with the practice of chemistry. As representative works of the phlogistic and of the anti-phlogistic schools re- spectively, there might be mentioned Georg Ernst Stahl's Fiuidamenta Chemiae DogiJiaticae et Ratioiialis and Antoine Laurent lyavoisier's Elements de Chimie, The original of the Lehr^hcch der Cheviie, by Berzelius, the first volume of w^hich appeared in 1808, experienced many editions and also a translation into the German tongue. This work remained an authoritative work during the greater part of the first half of this century. Among the standard English manuals of chemistry which this century has pro- duced, probably none outranks the Treatise on Chemistry, by Roscoe and Schorlemmer. Of English works of reference in this science, the Dictionary of Chemistry, by Henry Watts, and the 86 revised edition of this publication by Morley and Muir, undoubtedly hold first place. However, it would be a great and profitless task to attempt here a recital of the wealth of chemical literature — a store-house of treasure — to which all civilized nations of the world have con- tributed. Some conception of its ex- tent may be gained by learning that A Select Bibliography of Che^nistry^ 1492- 1892, prepared by the distinguished American bibliographer and chemist, H. Carrington Bolton, and published in 1893, enumerates no less than twelve thousand and thirty-one titles of inde- pendent books and their translations. Of these, four thousand five hundred and seven titles are credited to the Ger- man, two thousand seven hundred and sixty-five to the English, and two thou- sand one hundred and forty-one to the French language. Two supplements of this most valuable w^ork add respectively about six thousand and eight thousand titles to the number above given. The latter of these volumes is limited entirely to the recording of dissertations, while a Caialogice of Scien- tific Periodicals, in which of course many 87 journals on chemistry are included, and which has also issued from the pen of Professor Bolton, lists no less than eight thousand six hundred titles. Chem- Appreciation of the wide domain legi- Analysis timately open to chemistry brought with it application of its teachings and prin- ciples in many ways to many problems. The directing influence in such adapta- tions was, of course, chemical analysis, which has for its object the resolving of substances into, and a determination of, their components. With a perfecting of the methods of chemical analysis, a more accurate knowledge and understanding of the composition, the properties and the be- havior' of the substances analyzed was gained. In consequence, new processes of manufacture could be devised, those in existence could be more carefully fol- lowed, controlled and improved, and thereby, in many instances, a lowering in the cost of production effected. Notwithstanding the great importance of analytical chemistry, the purely scien- tific aspect of this branch of the science had, up to the present decade, been sadly neglected, although in its practical as- pects and details analytical chemistry 88 iad received great attention and care for many years. It was Wilhelm Ostwald's work, The Scientific Foundations of Aria- lytical Chemistry, published in 1894, which marked a pioneering venture into this inviting but theretofore practically unexplored domain. In chemical anal3^sis distinction is made between proximate and ultimate analysis. Aim of the former is the de- termination of individual groups existing in a substance. Thus, milk consists of water, fats, albumenoids, sugar and salts; a proximate analysis of milk would in- volve the determination of these consti- tuents, as such. Ultimate analysis is concerned with the determination of the individual ele- ments which enter into the constitution of a substance. In the illustration cited, for instance, it would be the task of ulti- mate analysis to determine the carbon, the hydrogen, the oxygen and all other elementary components of the substances which have been enumerated as consti- tuents of milk. Methods of chemical analysis must of course be adapted to the physical char- acter of the bodies to which they are applied. Gases, liquids, solids, call for 89 different modes of treatment, which must be especially suited and adapted to their respective properties. It is a frequent practice of the anal3^st to bring a body from one state of aggregation into an- other, for instance, to transform a solid substance into a solution, before subject- ing it to an anah^tical examination. When the object of an analysis is only the ascertaining of the constituents of a substance, — that is to say, when no at- tempt is made to determine how much of each constituent is present, — the process is designated one of qualitative analysis. If, however, a knowledge of the amounts in which the constituents are present be desired, the analysis assumes the character of a quantitative determina- tion. In practicing the latter, distinction is made between gravimetric anal3'sis and volumetric anah^sis, according to the manner in which the quantitative deter- mination is effected. If the amounts of substances are ascertained by weighing, the work is termed gravimetric ; if by the use of measured volumes of reagents, the process is designated one of volumetric analysis. It has already been mentioned that the era of quantitative anah^sis was intro- 90 duced through the balance coming into general use in chemistry. The refinement and degree of accuracy to which many modem chemical determinations can lay claim is marked, and this is, in no small measure, due to the exercise of the mechanical ingenuity and skill which are nowadays bestowed upon the manufac- ture of analytical balances. For many centuries, and in fact up to U'ithin a few centuries, fire was consid- ered to be the principal agent for the bringing about of chemical changes. How firm a hold this belief had on the minds of workers in the science, may be inferred from a motto placed in a text- book on chemistry that was published in 1663: Si7ie igni 7iihil operayiiur. Although fire played so prominent a role in the doings of the earlier investi- gators, yet the measurement of tempera- tures was but roughly approximate and very crude until Boerhave demonstrated the necessity and importance of employ- ing thermometers in many chemical in- vestigations. The construction of thermometers of the present type, containing a fluid, was first carried out about the middle of the 91 seventeenth, century, by members of the Academia del Cime?tto. Fahrenheit, in 1 714, employed mercury for the filling of thermometers, and Boerhave, in his famous treatise on chemistry, expressed the boiling- and the melting-points of substances in degrees Fahrenheit. To secure the heat needed for their operations, the alchemists and their suc- cessors in the science paid great attention to the form and to the construction of their furnaces. Among the fuels used were wood, wood-charcoal, coal, peat, alcohol and oil. For the obtaining of their highest temperatures they employed burning glasses, turning to the sun for the required energy. Some important additions to chemical knowledge resulted from so practical a sun-cult ; combustion of the diamond is, for instance, said to have been first accomplished by the help of the sun's rays. The obtainment of high temperatures by the use of oxygen was introduced by Priestley, who caused a jet of this gas to impinge on a glowing coal. The first apparatus in which hydrogen was burned in oxygen, was constructed by Hare, in 1 801. The two principal forms of dry analy- 92 sis which are practiced to-day are blow- pipe work, — which occupies itself with the behavior of substances under varying conditions of flame and generally in the presence of reagents, — and assaying, which is principalh' concerned with the determination of ores and metals by the processes of smelting and cupellation. The blowpipe, which was originally used for the soldering of metals, was first employed for the testing of minerals by Cronstedt and Engestroem. Bergman and one of his assistants, Johann Gottlieb Gahn, studied thoroughly the behavior of different substances and reagents un- der the flame of the blowpipe.- Their work on the testing of minerals by the blowpipe was published in 1779, and was the first treatise on this important branch of chemical analysis. Gahn's labors in this field continued for many years; after Berzelius had become his co-worker, the latter published a book on their methods and results, which experienced transla- tion into several languages. An Englishman, William Hyde Wol- laston, was another adept in the use of the blowpipe. He was a man of consid- erable ability and attainments, but per- haps his greatest achievement was the 93 working out of a method for the refining- of platinum, a method which could be applied on a manufacturing scale and which made possible the introduction of platinum vessels in the chemist's labora- tory. Assaying and blowpipe- work, or doci- macy, as it is often termed, are entirely distinct from the principles and methods of '' wet " analysis, a term often used to specify the working with solutions. This latter important branch of chem. istry received its first potent impulse through the labors of Bergman. His directions for the anal3'sis of mineral substances, which appeared in 1777 and the years following, were probably the first directions of the kind published. lu these he taught how minerals can be brought into a state of solution, by pow- dering them finely, by fusing them with the proper reagents and by then subject- ing them to the action of acids. While Bergman was thus probably the first to break ground in this new field, Martin Heinrich Klaproth was the one who fir«t brought chemical anatysis in- to systematic shape and who laid the foundations of that important structure, analytical chemistry, to the perfection of" 94 which so many able chemists have since given their best endeavors. One of the greatest benefits bestowed upon chemistry by Klaproth was the practice, which he was the first to intro- duce, of recording the results of his analyses exactly as he obtained them. As our mistakes should be stepping- stones to the truth, the value of Klap- roth' s procedure is patent. Thus, if the results of a complete analysis of a sub- stance should fall below loo per cent, to which they should figure, and if the dif- ference should prove too great to be accounted for on the plea of permissible experimental error, then search would naturally be instituted for the cause, duplicate analyses would be made, and the work, if faulty, corrected. If the duplicate analyses agreed, then there would be reason to suspect some con- stituent before not determined. Analysts prior to Klaproth did not pursue this course, and thereby they undoubtedly passed by many data which they could have secured. Klaproth left the imprint of his ability not only on analytical methods, but he likewise perfected much of the apparatus used in chemical manipulations ; the 95 introduction of silver crucibles, for in- stance, was due to him ; in fact, so great were his merits in these directions that he has been termed the ''creator" of analytical chemistr3^ In France the cause of analytical chem- istry was at that time furthered chiefly by Vauquelin, a pupil, and later on an assistant, of Fourcroy's. His researches extended to both mineral chemistry and to some of the so-called organic sub- stances. His lectures and his laboratory instruction were largely attended and exercised undoubted influence on the generation of chemists next succeeding. Of his writings, the Introduction to Chem- ical A?ialysis should be mentioned ; this was published in 1799, and a German translation of the same was made. Like several of his co-laborers in analytical chemistry, Vauquelin had the good for- tune to discover a new element, chro- mium. He also discovered and described the oxide of beryllium, the metal of which, beryllium, was isolated only thirty years later, by Wohler. The greatest improvements in analy- tical methods in those days were, how- ever, wrought by a Swedish chemist, Jons Jakob Berzelius, who had set for 96 himself as his goal the critical ex- amination of numerous chemical com- pounds in order to learn their exact composition and to discover the laws which governed their formation. His work pointed the way for the accurate determination of atomic weights and practically established the doctrine of proportions. Among the pupils of Berzelius, whose names are also deservedly eminent in the list of analytical chemists, there must be cited, Nils Nordenskjold, Heinrich and Gustav Rose, Mitscherlich, C. G. Gmelin and Friedrich Wohler. Heinrich Rose's Ausfuhrliches Ha7idbicch der Analytischen Ckemie long ranked as a model of its kind. Of English chemists who achieved marked success in this branch of chem- istry, there might be named Edward Howard, who gave much attention to the analysis of meteorites ; Smithson Tennant, who discovered osmium and. iridium, and who, in 1796, was the first to make an experimental investigation of the chemical nature of the diamond, showing the same to be but a pure form of carbon ; Dr. Henry, who devoted much skill to the analysis of gases, and 97 William Hyde Wollaston, whose worki has been previously referred to. One of the most distinguished analy- tical chemists of our own time was Carl Remigius Fresenius. An assistant of Justus von lyiebig's, in Giessen, and. later an assistant professor at that Uni- versity, he established at Wiesbaden, in - 1848, a laboratory which has since gained a world-wide reputation. His manuals on Qualitative and Quan- titative Analysis are to-day regarded as the standard works on these subjects, and his Zeitschrift fur Ayialytische Chemie, founded in 1862, is still the leading journal of its kind. Organic Before* the time of Robert Boyle, all and^Svn- substances were classified in accordance thesis with their physical properties. Chloride of zinc, chloride of antimony and chloride of arsenic were designated respectively as butyrum zinci, antimonii, arsenid, simply because they all had about the consistency of butter ; they were actually classed with this substance. Oil of vitriol, the sulphuric acid of to-day, was placed into the same group with the fatty oils, while sugar was counted in with the salts because it was a colorless ^ substance soluble in water. 98 In a text-book on chemistry, entitled Cours de Chymie^ first published in 1675, the author, Nicolas lycmery, classified substances according to their source or origin ; he thus distinguished three classes of bodies, — mineral, vegetable and animal. Lemery's book was at the time regarded as the standard work on chem- istry, and as it experienced translation into many tongues, his system of classifi- cation met with general acceptance. It was only towards the close of the last century that the products of the vegetable and animal kingdoms, so called,, received any appreciable attention from: chemists. Scheele and Bergman studied, some of the organic acids and worked out methods for their analysis, while the subject of animal chemistry received con- sideration at the hands of Rouelle. Lavoisier determined the constituents of vegetable compounds to be, usually,, oxygen, hydrogen and carbon ; animal substances, he found, contained in addi- tion nitrogen, and sometimes phosphorus.. In Lavoisier's eyes, oxygen was, so to- speak, the centre of the chemical world ;. in most instances he sought to determine whether a body was in combination with oxygen, or, if not, whether its combina- 99 tion with oxygen could be effected. To a body thus in combination or capable of combining with oxygen he applied the term '^radical"; a radical might be either a simple or a compound substance. This was, as previously stated, the foundation of the theory of compound, radicals later advanced by Berzelius. Sharp distinction between animal and vegetable chemistry was gradually al- lowed to fall into disuse when it was ascertained that there were some sub- stances which occurred in both the ani- mal and the vegetable world ; then the products of both of these kingdoms were grouped together as organic substances, and were classed apart from bodies of a mineral, or, as it was termed, an inorganic origin. Berzelius, after a most thorough re- search, reached the conclusion that the so-called organic bodies were in their composition also subject to the laws of constant and multiple proportions. The boundary line between organic and inorganic substances was, however, not clearly defined. Gmelin cited, as a distinguishing characteristic, that organic bodies could not be formed artificially from their components, while synthesis, which means a building up from their constituents, was possible in the case of inorganic compounds. But other views were also held, the chemists of that time being by no means agreed as to what constituted a proper definition of organic and of inorganic substances. The discovery by Friedrich Wohler, in 1828, that amonium cyanate, a mineral substance, could be transformed into urea, distinctively an animal product, marks the first drawing aside of the veil wherewith Dame Nature was believed to screen the mysteries of the living world. At that time, the belief was commonly held that all compounds found in the animal and in the vegetable kingdom owed their existence to the influence of a mysterious vital force. The elements under the domain of life were supposed to be governed by laws of their own, and, while it was known that substances found in plants and animals could be caused to undergo changes and transfor- mations, it was not believed to be pos- sible that they could be artificially made from their component elements. It was a long time ere the full and and general bearing of Wohler' s discov- ery came to be thoroughly appreciated, lOI ere the belief in a vital force was aban- doned to be replaced by a well-founded faith in the possibility of the synthesis of all organic compounds. Spec- When, in analytical determinations, Analvsi^ the means and methods of chemistry alone are not sufficient to secure the required degree of accuracy in the results sought for, the aid of a sister-science, generally of physics, is invoked. An illustration in point is spectrum analysis, a field of investigation opened up through the use of an instrument called a spectroscope. By the aid of this device the chemist is enabled to learn the composition of many substances under the sun, in fact, even of the sun, by ex- amining the light which comes to us from that bod3\ When a beam of sunlight is allowed to pass through a prism, the various rays of which the white light consists are unequally refracted, and, in consequence, are separated from one another in emerg- ing from the prism. These vari-colored rays, exhibiting all the colors of the rainbow, are designated as the spectrum. Three kinds of spectra are distin- guished. The solar spectrum and the spectra given out by the stars consist of colored bands traversed in certain parts by dark lines. Solids heated to incan- descence, but emitting no vapors — plati- num, for instance — give rise to continuous spectra, that is, to bands of color un- broken by dark lines. Vapors of vola- tile substances, especially vapors of the metals, cause so-called bright line spectra. As each metal has a spectrum peculiar ta itself and which is perfectly characteris- tic with respect to the color, the position and the number of the. lines it exhibits, the value of spectrum analysis for the purposes of chemical research will be readily appreciated. Credit for applying the principles of spectrum analysis to problems of chem- istry belongs to two German chemists, Bunsen and Kirchhoff. By its aid they discovered the elements caesium and rubidium ; gallium, thallium and indium were likewise discovered by means of the spectroscope, by other analysts. In an address, entitled ' ' The Chem-^ istry of the Stars," recently delivered by J. Norman Lockyer, this distinguished scientist, after recounting recent infor- mation gained in stellar chemistry by means of the spectroscope, referred to the process of celestial evolution, and 103 suggested the probability that all cos- mical bodies were evolved from meteor- ites. Surely a great and important generalization to found on evidence sup- plied by a method of nature-study which had its modest beginning onl}- at the beginning of this centur3\ Electro- One of the most important advances istry i^ade in chemistry in the first decade of the nineteenth century, was the securing" of two new elements, potassium and sodium, from their compounds, potash and soda respectively, by the aid of electrical power. This was accomplished in 1807 by Sir Humphry Davy, who used electric currents in these investigations. Water had been decomposed electro- lytically, seven years earlier, by Nichol- son and Carlisle. Berzelius had tried the action of electricity on salt solutions, ammonia and other compounds, and Sir Humphry Davy commenced his work in this direction by a very careful study of the electrolytic decomposition of water. Davy's observations laid the founda- tion of the electro-chemical theory, w^hich, later on, was materially enlarged and elaborated by Berzelius. A number of new elements were discovered by dis- sociating chemical compounds by the aid 104 of the electric current. Besides potas- sium and sodium, calcium, barium, strontium, chlorine and iodine were thus added to the list of chemical elements. Among the French, these researches excited great interest, and Gay-IyUssac and Thenard paid great attention to the preparation of the alkalies named, potas- sium and sodium, by electro-chemical methods, in addition to seeking to obtain these metals by other processes of manu- facture. Employment of the electric current for the separation of metals was advocated in 1865 by Liickow, and its introduction into analytical chemistry was due chiefly to this investigator and to Gibbs. Within the past decade, thanks to the efforts of Wilhelm Ostwald, Alexander Classen, Robert Liipke, Edgar F. Smith and others, the methods of electro-chem- istry have reached so advanced a stage, that regular systems of qualitative analysis by electric currents have been devised, and by these means and methods satisfactory determinations of many bodies can now be made. A study of the influence of electricity on certain of the so-called organic vSub- stances is one of the latest phases upon 105 which electro-chemical investigation has entered. Physical Fraught with potent powers for the ist?y ^^^^' f^^ ^-^^ advancement of all chemical knowledge, are the teachings of physical chemistry. Physical chemistry is the name by which there is designated that border-land of science lying between chemistry and physics. Its scope may perhaps best be defined by stating that it aims at the solving of chemical problems by physical means and also at the solving of problems in physics b}^ invoking the aid of chem- ical methods. A pioneer in this field was Olivet Wolcott Gibbs, a distinguished Americai^ chemist. In German}-, Wilhelm Ostwald, AV. Xernst and J. H. Van't HofI are among the leaders of the movement along these lines. Other chemists whose names are iden- tified with advanced work in pure chem- istry are : Ira Remsen, J. P. Cooke, William Crookes, Arrhenius, Raoult, Wurtz, Le Bel, Guldberg and Waage. In Germany, the Zeitschrift fi'ir Physi- kalische Cheiiiie^ edited by Ostwald and Nernst ; in America, The Journal of Physical Chemistry, edited by Bancroft io6 and Trevor, are the representative organs of this especial branch of the science. We may here not transgress into this fascinating domain nor enter into a dis- cussion of its interesting possibilities. Exploration of it has, so to say, hardly commenced, but even so, it has already yielded great treasures to science and is full of promise for the future. The origin of metallurgical knowledge Metal- dates back to prehistoric times, different qu^^ . nations ascribing the creation of the art istry to their gods and heroes. Gold and silver were probably the ear- liest known of the metals ; this is easily accounted for through their occurring in the native state, that is to vSay, in the elemental condition, so that they could be employed as found, without first hav- ing to be obtained from their ores. The oldest manufactured object of gold to w^hich a date can be assigned is a bead, shaped somewhat like a crescent, which was found by Monsieur de Morgan in a royal tomb at Nagada, in Egypt ; the probable date of erection of that struc- ture is about 4400 B.C. Nearly all ancient articles of gold which have been analyzed have been found to contain some silver. This 107 natural alloy of gold and silver— for such it may be considered — was termed electrum ; it occurred in considerable quantity in Asia Minor. The earliest coins, the introduction of which Herod- otus ascribes to the Iv3^dians, were made of electrum. They resembled oval bul- lets in shape and were stamped on one side only. Their use dates back about seven centuries before the beginning of our chronology. Pure silver in ancient times seems to have been used principally for the mak- ing of jewelry and of other ornaments. Reference to a ring of silver is to be found in a translation of The Book of the Dead by Wallis Budge ; this reference would seem to make the existence of silver rings date back to at least 3600 B.C. Copper and its alloy, bronze, have been known from the very earliest of times ; articles made therefrom have, it is claimed, been found in deposits dating back to the age of stone. In the tomb at Nagada, previously referred to, there was also found a button, which, accord- ing to the analysis of Berthelot, consisted almost wholly of pure copper. Copper articles of somewhat later dates are frequently found to contain arsenic ; 108 this was probably added to harden the copper. Tin alloyed with copper consti- tutes bronze ; objects made of this mate- rial were used in Egypt evidently in very early times. The use of iron was known to the Egyptians long before this metal passed into the hands of the Greeks and Ro- mans. The time when it was first used in Egypt is a matter of dispute. Lepsius holds that it was there employed fully five thousand years ago. Strange as it may seem, in spite of its wide usefulness this metal was regarded by the Egyptians as '* the impure metal/' and its handling was held to be a sin. This ancient superstition passed, together wnth the metal, into the keeping of other nations and may to this day be traced in various countries far distant from each other ; it is, for instance, encountered in Africa, in China and in Scotland. Several metallurgical operations were known to the Romans and the Greeks, but hardly any information has come down to us concerning the chemical pro- cesses employed in those times. Diodo- rus, in the second century before our era, described a process of cupelling gold for removing impurities from that metal. 109 The process of heating cinnabar with iron, in order to obtain metalUc mercury from this compound of mercury and sul- phur, was also then known. Mining was actively pursued in various countries, notabl}^ in Spain, France and Germany, as early as the eleventh cen- tury ; the mercury deposits in Idria w^ere discovered towards the end of the fif- teenth century, and the tin mines of England have been worked since very early times. During the age of medical chemistry Agricola carefully described the chemical operations involved in metallurgical pro- cesses. By-products were noticed and secured, and about the middle of the six- teenth centur}^ the discovery was made, in Germany, that cobalt oxide imparts a hlue color to glass. The eighteenth centur}^ brought Berg- man's investigation on the differences between cast - iron, wrought - iron and -Steel ; Reaumur's teaching of a practical process for the making of steel from iron, and Duhamel's study of the making of brass. About that time several trea- tises on metallurgy were published, among them Schlueter's extensive work, w^hich appeared in 1738. In the nineteenth century the process of making steel, devised by Sir Henry Bessemer, in 1856, has been perhaps the most important and, in its effects, the most far-reaching of all of the numerous advances made in metallurgical opera- tions. The removal of phosphorus from iron, by the Thomas-Gilchrist process, and the utilization of the resulting slag as a valuable fertilizer, mark other achievements of this century in this par- ticular field, which are of great import- ance and value. Considerable attention has also been given within recent decades to the mak- ing of various combinations of metals, alloys, as they are termed. New varieties of brass and of bronze have been manu- factured ; aluminium, which owes its present prominent position in the world of metals in a great measure to its cheap production by electro-chemical processes, forms the basis of a number of exceed- ingly valuable alloys, bronzes and others. Various methods have also been found for securing the intimate combination of iron and steel with varying amounts of carbon, nickel and other elements. This results in the securing of great strength and power of resistance for the finished III products. In this respect, indeed, tlie great and enduring struggle for supre- macy going on, the civilized world over, between heavy armorplate for purposes of defense and heavy projectiles for pur- poses of attack, may well be looked upon as an episode in the evolution of this particular branch of metallurgical chem- istry. Quite recently the United States Navy Department has received an extensive report concerning a very important ex- periment which extended over a period of four years, and which was made to determine the feasibility of attaching a covering of copper directly to the steel or iron hulls of vessels. The process employed is practically one of electro-plating, the copper being, as it were, fused directly into the plates of iron or steel. The coating of copper thus applied has a thickness of about one thirty-second of an inch. The results obtained in this Govern- ment trial have proved eminently satis- factory in every respect. The process is less costly than the process of copper- sheathing as ordinarily employed ; the hull of the vessel experimented upon was found to be free from all barnacles, even IT2 after long continued service in southern waters, and last, but not least, it was established that no galvanic action had been set up between the iron and the copper, although such an occurence might have been feared. Taken all in all, the successful out- come of this crucial test seems to mark a new departure along lines where the need of improvement had long been felt and sought, and this new process will pro- bably prove to be of the greatest value to the shipping interests of the world. Incidental reference should here be made to the various metallic pigments which play quite a role in the arts and industries. Among such colors, we have white lead, paris green, zinc white and iron ochre. Salts of iron, chromium, aluminium, tin and potassium are also largely used in the dyeing and the print- ing of textile fabrics. The marvelous advances made by elec- tricity have caused its influence to be strongly felt also in matters chemical. The winning of metals by electrical pro- cesses has previously been mentioned, and the practical applications of electro- metallurgy in the arts and in manufacture are numerous. "3 Electro-plating, the process of covering' surfaces with metallic deposits thrown down from solutions of their salts by electrical currents, has made wonderful strides since the first inception of the idea by de la Rive, in 1836. The production of whole series of chemical compounds, for instance, the silicides and the carbides, is also effected through the aid of powerful electric currents, which are caused to generate intense heat. Thus, carborundum, which is a carbide of silicon, is formed in the manner indicated, from a mixture of coal, sand and salt ; it has found con- siderable application in the arts, on account of its very great hardness, it replaces emery for many purposes and it is also used in the making of steel. Calcium carbide, which is made by fusing coke and lime in an electric fur- nace, 3'ields, when brought into contact with water, that brilliant illuminant, acetylene, which of late has entered into active competition with the illuminating gas now in common use. Mineral- The analytical work of Bergman, Ch^^^- ^^^^<^^^^^^ ^^^d Klaproth forms the true istry foundation of mineralogical chemistry, although sundry scattered observations 114 on the nature of minerals were made even in the seventeenth century. It was Hauy who called attention to the importance of the crystalline struc- ture of minerals, and in his system of classification he paid due regard no less to their physical than to their chemical properties. In 1824, Berzelius announced his clas- sification of minerals. This was based principally upon his own numerous analyses and soon displaced all other systems. At one time considerable importance was attached to the theory of isomor- phism, advanced by Eilhard Mitscherlich. This theory held that identity of crys- talline form was dependent only upon the number and the arrangement of the atoms in a molecule and was in no wise influenced by the chemical nature of these atoms. According to Mitscher- lich' s teachings, an equal number of atoms united in the same manner would always give rise to one and the same crystalline form. Among those who have been or are active workers in mineralogical chem- istry, there should be cited the names of James D. Dana, whose Text-book of 115 Mineralogy is a standard work, and C. Rammelsberg, of Berlin, the author of the Handbiich der Mineralchemie , who in his day also contributed largely to the advancement of this branch of chemistry. The first half of this century witnessed a few isolated attempts at the artificial formation of minerals, for instance, Gustav Rose's work on calc-spar and arragonite. But synthetic mineralogy, the producing of minerals in the labora- tory while seeking to imitate Nature's conditions, dates virtually from the 3^ear 1 85 1, when systematic attempts in this direction were first planned and made. J The methods employed embraced work w^ith solutions as well as with fusions carried out at high temperatures ; the results have proven of great value to geology, by making possible the testing of many geological h3^potheses and by leading to the advancing of new theories. Geo- Among the most eminent German ^gical ^^orkers in chemical geology were Bun- istry sen, who carefully studied the geysers of Iceland, and G. Bischof, who published a valuable treatise on the subject, the Lehrbuch der Chemischeii Geologie. Of American geologists who have attained to eminence in this field of 116 work, there should be named Thomas Sterry Hunt, who was long active in the geological surv^ey of Canada and whose work on questions of chemical mineral- ogy is highly esteemed, and James Furman Kemp, whose standard pub- lications on geology also contain various important contributions on topics of this character. The French have been most active in the synthetic work along these lines — to mention only St. Claire Deville, Troost, Sarasin and Moissan. Moissan, in 1892, succeeded in making minute diamonds by exposing sugar-carbon and iron filings, while under great pressure, to a temperature of over five thousand de- grees and then suddenly cooling the mass. A sudden chilling, under enormous pressure, seems to be a necessary con- dition for the synthesis of diamonds ; geologists have not yet succeeded in determining the mother- rock of this gem. An h3'pothesis recently advanced would assign to all diamonds an extra-terrestrial origin, holding that they are brought to this world by meteorites. Three sep- arate finds of diamonds in meteorites have been made. One of these mes- 117 sengers from space fell in Chile, another^ in Siberia and the third in Arizona, f U. S. America. ■ While there is not, as 3^et, sufi&cient evidence at hand to establish the above mentioned hypothesis on anything like a probable basis, yet it remains an inter- esting fact that Moissan succeeded in obtaining diamonds synthetically, under conditions analogous to those to which meteorites that reach this earth are supposed to be subjected at one period of their existence. Phyto- The beginnings of phyto-chemistry, istry ^^^ chemistry of plant-life, can be traced back to investigations made at the close of the eighteenth century. Priestley, Senebier and others were familiar with the fact that green plants under the influence of sunlight v/ill re- move carbonic acid gas from the atmos- phere and decompose it. They were also aware of the fact that ammonia salts are of value in stimulating the growth of plants. Although the problems of plant-life, the mode and manner of plant-nourish- ment and growth, had engaged the labors of many trained observers for many years, yet, even during the first ii8 three decades of this century the belief was almost universal that plants, like animals, derived their nourishment di- rectly from organic matter. It was Justus von Liebig who demon- strated the falsity of these views and who entirely disproved the humus-doctrine, as the theory held at that time was called. It was in 1840, after exhaustive investigations on the weathering of rocks, on the formation of soils and on the effects of rain and the gases which rain holds in solution, that von lyiebig pub- lished his classic work on the application of chemistry to agriculture and physi- ology. In this he demonstrated that the food of plants is inorganic in its nature. The parts played by carbonic acid, by water, by ammonia and by various mineral salts were pointed out, and the fact was estab- lished that restitution must be made to the soil of such constituents as are re- moved therefrom by vegetable growth, if a given soil is to continue producing crops indefinitely. When Nature is left to her own time and devices, she replenishes the needed store by the disintegration of the rocks. This is accomplished through the agency "9 of frost, by the solvent power of water containing carbonic acid, and, last but not least, through the silent but ever- active agency of the industrious earth- worms. Our knowledge of the last named we owe chiefly to the illustrious naturalist, Charles Darwin. Earth-worms live in burrows, in the superficial layers of the ground. They can live anywhere in a layer of earth, provided only that the same retains a sufficient store of moisture, for dry air is fatal to them. The}^ live principally in the mold, less than one foot below the surface, but in dry weather they sometimes go down to a depth of eight feet. Their burrows end in small chambers, large enough to admit of the worms turn- ing in them. These burrows are formed through the earth being swallowed by the worms for the sake of the decomposing vegetable matter which it contains and on which the worms feed ; leaves also form part of the diet of these little animals. When decaying, these leaves give rise to the formation of certain, acids, but these acids are neutralized by some carbonate of calcium secreted by certain small glands the worms possess ; these glands empty into the alimentary canal. Digestion of the vegetable matter is secured by the aid of a digestive fluid which resembles the pancreatic juice of the higher animals ; it acts only when alkaline. One part of the alimentary canal of these worms forms a hard, muscular organ, which is capable of grinding the food into fine particles. Small stones, swallowed with the earth, act as mill- stones, and the earth therefore is con- tinually, as it were, passing through a mill, and is thus being constantly ground into a fine mold. After the earth has been thus treated by the earth-worms it is voided as cast- ings. The mold in a field passes through the bodies of these worms several times a day, and the earth particles are there- fore brought to the surface again and again to be acted on by the rain and carbonic acid. Furthermore, through, the collapsing of old burrows the mold! is kept constantly in slow movement, and its particles are thus continually ground against one another. It has been cal- culated that in one acre of land, suited to their needs, more than fifty thousand earth-worms can exist ; the importance 121 of their influence may therefore be readily inferred. However, when the conditions are suck that land cannot be allowed to lie fallow for the length of time needed by nature to carry out her purpose, chemistry comes to the rescue, and, accomplishing in a few hours the task that without her aid- would have required years, gives to the cultivator of the soil fertilizers, the needed food for his crops, in a form to be readily assimilated by the plants. Chemistry has taught man to know aright the requirements of Mother Earth, the conditions w^hich must be fulfilled to ensure bountiful crops. No longer need virgins be sacrificed to the Genius of Maize, as was done by some tribes of American Indians, in order to plead for a generous yield of the life-sustaining cereal. Notwithstanding the fact that the questions how plants feed and how plants- grow have claimed the interest and the- earnest work of many distinguished in- vestigators these many years, we have as yet no positive knowledge as to the exact manner in which the inorganic constituents, water and carbonic acid gas, are by the plants transformed into^ organic products, such as starch, the sugars and cellulose. These substances, produced by the plants are the food of animals ; these in turn, when they die, again furnish the chemical compounds necessary for the life and the growth of plants, thus establishing and completing^ an endless cycle. Another tempting problem which has received much attention at the hands of phyto-chemists, but which has as yet not found its full solution, is the chemistr^^ of the color changes which foliage ex- periences in the fall. It is, of course, well known that plants, their leaves and their flow^ers owe their colors primarily to the magic touch of light. Thus, a leaf in its period of vitality absorbs all tints of light except the green ; this it reflects, and hence the leaf shows a green color. But as the vitality of the leaf declines, changes — chemical changes — occur in at least one. of its constituents, the chlorophyll, and then the sunlight falling upon the leaf is differently affected. Various hues are reflected as the chemical changes pro- gress. The leaf, erstwhile green, assumes in turn tints of yellow, orange, red — a play of colors which serves to render our 123 woodlands so beautiful in autumn. It has been stated that the sequence in which the colors of the turning leaves appear is the same as the order in which the colors of the spectrum range ; fol- lowing the green come yellow, orange and red — evidently favorite tints on the palette of Nature. Techno- The achievements of chemistry in the Chem- ^^^^ ^^^ industries are so vast and so istry varied, that the mere attempt to enumer- ate them all would prove a task scarcely less formidable than the counting of the denizens of starland, some twenty thousand of which are believed to exist for every one that is visible to the un- aided eye. Pure chemistry and applied chemistry are ever inter-active. The latter profits by the advances made by the former, while pure chemistry is in turn benefited by the new possibilities and opportuni- ties created and offered by the industries. While the evolution of the science and its ministrations have gone hand in hand, yet it is unquestioned that a practical, an empirical knowledge was had of many processes, chemical in their nature, long before there was any true conception of their character. 124 Of the older nations the Egyptians were probably most favored with knowl- edge of this description. They were familiar wnth certain metallurgical pro- cesses ; for instance, the working of iron and its tempering ; gold was by them fashioned into ornaments, the rich mines of Nubia furnishing them with most of this precious metal. To them was known the art of potter}^ the glazing of earthenware and the use of colored enamels. The manufacture of glass was also practiced in Eg^'pt and is supposed to have originated through an accidental fusion of sand and soda, in the fluxing of gold. The making of glass vessels was carried on extensively in Thebes and even the making of arti- ficial gems of glass was known in Egypt in its early days. Dyeing fabrics and the use of mor- dants for the purposes of fixing certain colors on cloth was known to both the Egyptians and Phoenicians. The former also used chemical substances in their practice of the healing art and in the embalming of their dead. The tanning of leather by oil and later by means of bark was practiced by some nations of old. The use of soaps — com- 125 pounds of fats and an alkali — was known in Germany and in Gaul, even in the times of Pliny ; the purifying of clothes by the burning of sulphur is also men- tioned by this author. Acetic acid, in the form of vinegar, w^as another chemical agent with the properties of which antiquity w^as ac- quainted. This is apparent from the use Cleopatra is said to have put it to as a solvent for some valuable pearls ; this solution she drank, the act being prompted by her desire to gain the dis- tinction of having partaken of the most costly banquet that could be furnished. Technological chemistry finds a wdde field of usefulness in the treatment of many substances which occur in nature and which possess a certain value even in their crude, natural condition, but which can be much improved in quality and in value by appropriate processes. Thus it is probable that the sugar- cane, as such, serv^ed as food before any attempt w^as made to express its juice and to boil the same into syrup. It is likely that this practice originated in India. The first making of solid sugar must be placed somewhere between the fourth 126 and the seventh century of our era, pro- bably nearer to the latter than the former date. The earliest description given of its manufacture is by a Chinese traveler, Hiuen-Thsang, who saw the process carried on in India and who assigned to the solid sugar the name Chimi — a Chinese term signifying ' ' stone-honey. ' ' Even a few centuries ago sugar was regarded as a luxury. In 1372 sugar was valued in France at five dollars a pound ; at the close of the sixteenth century its price in that country was still almost a dollar per pound and similar values obtained elsewhere. In view of such figures it does not seem difficult to place credence in the tale of the thrifty housewives of New Amsterdam, who, so tradition affirms, were wont to provide but one lump of sugar, fastened by a string to the rafters of the dining-room, for the common use and enjoyment of the household. Surely an impressive object-lesson on the diffi- culty of attaining to the sweets of life ! But now, thanks in great measure to the advance of technological chemistry, sugar has become a cheap food-staple of many countries, the total world pro- duction of this article — ''crystallized 127 sunshine' ' as it has so aptly been termed — now approximating to seven millions of tons per annum, and representing a value of many millions of dollars. Coal tar is the basis of many brilliant colors and of many valuable medicinal preparations. From it there has also been obtained a sweetening agent, sac- charin, which of late years, under various names, has been offered as a substitute for sugar. Saccharin, or, to give it its proper chemical appellation, anhydro-ortho-sul- phamid-benzoic-acid, is a compound of the elements carbon, hydrogen, oxygen, sulphur and nitrogen ; it was discovered in 1879. It is a white, crystalline sub- stance, soluble, though not readily so, in cold water and is characterized by an intensely sweet taste ; its sweetening power is estimated to be, for equal w^eights, from three hundred to five hun- dred times that of pure sugar. While saccharin and other similar sub- stances may have some value as medi- cinal agents, their attempted substitution for sugar in the preparation of food and drink is decidedly reprehensible. Not only is sugar a true food, which saccharin is not, for taken into the system it is 128 eliminated unchanged, but there is abundant evidence on record establishing the fact that saccharin interferes with the proper exercise of the digestive function. In some instances even de- cidedly injurious effects on men and on animals have followed the use of this preparation. Many attempts have been made to produce food- substances synthetically. While it is claimed that the syntheses of sugar and albumen have been accom- plished, yet we are to-day as far as ever from having achieved any practical results along these lines. In some instances, however, valuable results have been obtained in modifying certain natural products in such a man- ner as to fit them for consumption as food-stuffs. An illustration in point is the manufacture of oleomargarine, but- terine or artificial butter, as it is called, which dates back to the experiments of Mege-Mouries, in 1870. In a tank heated with steam he ren- dered carefully washed beef-suet with some water, a little potassium carbonate and some pepsin. After digestion of the mixture for the proper length of time and after the melted fats had risen to 129 the surface, some salt was added and the fat was removed. It was allowed to cool, to permit of the crystallizing out of some of its constituents, and the fluid oil remaining, the oleopalmitin, was squeezed out by presses. To the oil thus obtained some milk or cream and a little butter- color were added, the mixture w^as well churned and salted and was then ready for the market. Leaf-lard is now largely used as the crude material in this process. In cold weather a little pure cottonseed oil is added to it in order to give an improved texture to the finished product. This industry has attained to considerable im- portance. Endeavors have also been made to- furnish the essence of foods in a compact form. For it is possible to put much food into a condensed form in which it will keep properly for a considerable length of time. Food tablets have been prepared of soup, of beef, of milk and of eggs, forming as it were, the very essence of nutriment. But very grave doubts exist whether food in such a form can and will be pro- perly assimilated by the animal system ; in fact, some experiments made a year 130 or two ago by some United States troops in Colorado, with the so-called emergency ration, returned a very decisive negative in answer to the question. In this connection reference may not be amiss to the interesting fact, that of late the preparation of carbonated liquids has been made very convenient through the introduction of small iron capsules charged with liquefied carbonic acid ; the capsules contain each about two grammes of the liquefied gas, a charge amply suffi- cient for the conversion of at least a quart of water, or other liquid, into a sparkling, refreshing beverage. However, it would lead too far afield, even should one only attempt to indicate all the many chemical processes to which so great a number of the necessities, and the comfojts of our daily life are owing. As furnishing a basis for many of these industries, there would have to be consi- dered the manufacture of the mineral acids — hydrochloric, sulphuric and nitric; also the preparation of sodium carbonate and of other alkaline products. The manufacture of textile fabrics of various materials — silk , wool , cotton , linen — would have to claim our attention. So 131 would the preparation of many colors and dyestuffs derived from animal, vege- table and mineral sources ; the art of pottery and ceramics ; the manufacture of paper, of ink, of matches ; the com- pounding of gun-powder and of smoke- less powders, of nitro-glycerine and of other high explosives, with their power- ful mission in peace and in war. Besides, the making of sugar, the pre- paration of starch, of flour and glucose, the manufacture of alcoholic beverages of various kinds, the preservation of cer- tain foods — one and all might be studied and called upon to bear witness to the importance of chemistry in its applica- tions. But, as it is not feasible to discuss all these in detail, interesting as it might be, there shall here be chosen in illustration but a few instances where the creative power of chemical science stands clearly revealed. The preparation of artificial silk from cellulose is an instance in kind. Cellu- lose is the fundamental constituent of plant structure ; it forms a material part of the solid matter of every plant. In its chemical composition it is allied to starch, being, like starch, a compound of carbon, 132 of hydrogen and oxygen and having the same percentage composition as starch. Cellulose is insoluble in water and in alcohol, it is tasteless and is not a nutrient. In the process here to be con- sidered, the cellulose is brought into so- lution by treatment with chloride of zinc, and this solution is then forced in fine jets into a fluid like alcohol or acetone. This causes the precipitation of the cellu- lose in the form of fine continuous threads ; the reagents are dissolved and w^ashed out, leaving only the desired product. The threads so obtained can be colored at will ; they can also be made waterproof and can of course be woven into fabrics of any desired shape and size. The finished article resembles silk so closely that even connoisseurs of the silkworm's product cannot always distin- guish between the latter and its fLii-de- Steele rival. In this case it is a substance of animal origin which is skilfully imitated by chemical processes ; in the manufacture of artificial India rubber w^e have an in- stance of the substitution, after the proper treatment, of one vegetable pro- duct for another. An English chemist, \V. A. Tilden, 133 discovered that a peculiar liquid sub- stance, isoprene, which had previously been obtained by the destructive distilla- tion of India rubber, could be obtained by the influence of heat upon oil of tur- pentine, rape-seed, linseed and various other vegetable oils. Isoprene is a compound of carbon and hydrogen ; it boils at a low temperature, about 40° Fahrenheit, and is converted, by treatment with strong mineral acids, hydrochloric acid, for instance, into a solid which is tough and elastic and which, also in other respects closely re- sembles India rubber. Many attempts have been made to provide synthetic sub- stitutes for both gutta percha and India rubber ; the process here referred to for obtaining the latter certainly seems a promising one, if only it can be properly controlled on a manufacturing scale. Many essential oils and other organic substances have been synthetically pre- pared. Among them benzaldehyde, the principal constituent of oil of bitter al- monds, oil of cinnamon, cumarin — to which the Tonka bean owes its delicate aroma — and vanillin, the odorous prin- ciple of the vanilla-bean. This vanillin is made from coniferin, a substance which 134 occurs in spruces, in firs and in larches. Even the flower's subtle charm, its perfume, needs no longer be extracted from the blossoms ; for the odors of the heliotrope, the violet, the lilac and ger- anium, these and many more, can now be made in the laboratory and are as fragrant as though they owed their ex- istence to the favored children of the dew and the sunshine. Possibly one of the most striking achievements of technological chemistry is presented by the wonderful array of beautiful and brilliant colors w^hich the chemist's art has called forth from coal- tar and from other apparently most unpro- mising sources. The great and extensive coal-tar color industry is built, in great part, upon the exhaustive studies of the famous German chemist, x\ugust Wilhelm von Hofmann, a man in whom there were combined to a rare degree the essential qualifications which mark the scientific investigator, the teacher and the scholar. The aniline colors now number several hundreds and have almost wholly re- placed the coloring matters formerly used — indigo, madder- root, cochineal, safflower and the yellow dye-woods. Perkin, in 1S56, made mauve from 135 aniline, one of the constituents of coal- tar oil. This was the first aniline dye to be prepared on a large scale. A synthesis in organic chemistry which has produced far - reaching results in several directions, was the artificial pre- paration of alizarin by Grabe and Lieber- mann. Alizarin is one of the coloring matters which occur in the madder-root. Its name was bestowed upon it by its discoverers, Colin and Robiquet, in 1826, the term being taken from the oriental appellation of madder, alizari. The root of this plant has been used in Eg3'pt and in India, since time imme- morial, for the dyeing of cloth ; wrap- pings found on mummies proved to have been colored by this substance. The culture of the madder plant was also practised extensively in Holland, in France and in Alsace, and about forty years ago the total annual production of madder was not far from five hundred thousand tons. Grabe and Liebermann found, as be- fore stated, that alizarin could be artifi- cially prepared ; they obtained it, by a series of ingenious chemical reactions, from anthracene, a constituent of coal- tar. This was the first instance of the 136 o synthethic production of a colorin principle which had formerly been obtained exclusively from a vegetable source. One of th® important results of this famous discovery was the turning over to agriculture for its purposes of vast tracts of land, w^hich had up to that time been used for the cultivation of the madder-root. Grabe and Liebermann's achievement also, incidentally, stimu- lated greatly the coal-tar industries and increased materially the manufacture of caustic soda and of sulphur trioxide. Another instance, w^here synthetic chemistry produced a color that had for many centuries been obtained only from plants, we have in the artificial manufac- ture of indigo. This substance was used very long ago in India as w^ell as in Egypt. In Europe, the w^oad, w^hich also belongs to the plants that produce indigo, w^as for ages the chief source of supply of this dye ; its use by the Gauls and by the ancient Britons is clearly -established. In Germany its cultivation was practised as early as the sixth cen- tury and was carried on for many centu- ries thereafter. But gradually woad was supplanted by indigo and the use of this 137 substance as a blue pigment and as a dye became general. The chemical composition of indigo received attention at the hands of several chemists. Fritzsche, in 1840, distilled indigo with caustic soda and secured a substance which he called aniline. This term is derived from the Sanscrit appel- lation 7iila, the indigo-plant, the word 7iila signifying dark-blue ; as a matter of interest it may here be remarked that the name of the river Nile is said to be traceable to the same source. Many chemists were concerned with the investigation of indigo. To name but a few, we have lyaurent, Erdmann, Baeyer, Knop, Emmerling and Nencke. The last named succeeded, in 1875, in obtain- ing a small amount of artificial indigo by the action of ozonised air on indol. At present several methods of indigo-syn- thesis are known. The synthetical preparation of ultra- marine, a substance which replaced the costly lapis lazuli used in the painter's art, was effected after chemical analysis had revealed its quantitative composi- tion. This will serve as an illustration of a mineral substance successfully pro- duced in the laboratory and leading to 138 "the establishing of an important manu- facturing industry. Any consideration of technological chemistry, however brief, would be in- complete without at least a passing refer- ence to a recent achievement which is fraught with great possibilities for the future of many chemical processes — reference is made to the liquefaction of air on a commercial scale. The possibility of the liquefaction of air, in quantity, was demonstrated in 1893 by James Dewar, of Edinburgh; Olszewski, of the University of Cracow, claims to have obtained this substance in small quantities even in 1884. Dewar' s method of procedure consisted in making use of liquefied carbonic acid or of ammonia, which, by its evaporation ensured the liquefaction of another gas, ethylene. This liquid was in turn em- ployed to cool and to liquefy still other gases and liquid air was finally obtained as the end-result of a series of such oper- ations. It proved, however, a costly treasurCj Dewar estimating the expense of obtain- ing a quart of liquid air at something more than two thousand dollars. It remained for the practical ingenuity 139 of an American, Charles E. Tripler, of New York, to devise a process by which liquid air can be obtained so readily and at a cost sufficiently low to make it avail- able for many purposes and in any quan- tity desired. Mr. Tripler' s process is based on the principle that gases which have been subjected to great pressure absorb much heat on being again allowed to expand. B}' means of a forty horse-power en- gine, provided with three pistons fur- nishing respective!}' sixt}', three hundred and two thousand pounds of pressure to the square inch, air in liquid form is produced solely through the aid of ordi- nary air which has been subjected to cooling and to these pressures. The temperature of the air to be liqui- fied is lowered to 312° below zero on Fahrenheit's scale. At this point it turns into a liquid that is practically colorless. Air, as is well known, is essentially a mixture of oxygen and nitrogen — by volume, approximately one-fifth of the former and four-fifths of the latter gas. Nitrogen evaporates more rapidly from liquid air than oxygen and, in conse- quence, liquid air undergoes changes iu 140 its composition on suffering evaporation ; it grows constantly richer in oxygen. The chemical and physical properties of most bodies when brought into contact with liquid air are so wholly unlike the properties they exhibit at ordinary tem- peratures, that their study under these novel conditions seems like the opening up of a new realm to the explorer — an Arctic region, as it were, replete with wonders. It must certainly be counted a great triumph of Science that she can thus impress into service the forces of Nature, and produce a cold so intense, that, by comparison with it, the lowest tempera- ture ever recorded by intrepid explorers of the frozen North sinks into insigni- ficance. Liquid air when poured over ice boils at once and becomes transformed into vapor. As its temperature is more than 300 degrees below the temperature of ice, this result, startling as it seems, is inevitable. Thrown into a vessel of boiling water, liquid air instantly changes the boiling water into ice ; a jet of steam forced into liquid air immediately con- geals into glittering crystals of frost. Mercury, immersed in this novel re- 141 agent, becomes a solid, which is so hard,, that, appropriately shaped, it can to alt intents and purposes be used as a ham- mer as long as the magic spell of the frost-giant endures. Most metals and many other substances turn brittle as glass when they are sub- jected to the action of liquid air. On account of its richness in oxygen, con- stantly increasing, it will be remembered,, as its evaporation progresses, the pre- sence of liquid air readily ensures com- bustion. Wires of iron and steel will, w^hen ignited, burn freely in this liquid — itself so intensely cold. Employment of liquid air as the motive power in engines of all kinds, application, of its tremendous expansive and explo- sive force to the purposes of industry and of war, mark but a few of its many uses which the future will witness. As soon as man shall have learned to perfectly control this new and powerful agent — advances in that direction have even now been made — it stands unques- tioned that it will prove a potent factor for the good of mankind and the pro-^ gress of civilization. Pharma- The beginnings of pharmaceutical, chemistry must be traced to the age of 142 iatro-chemistry, for at that period the Chem* preparation of medicines was the chief aim of chemistry. Paracelsus may be regarded as one of the founders of pharmacy, inasmuch as he introduced into medicine the use of many chemical preparations employed even to this day. He prescribed as drugs, many metallic compounds ; among others salts of copper, of lead, of arsenic, of mercury and antimony. In the use of the last named he had, however, been preceded by Basil Valentine. Tincture of iron, dilute sulphuric acid, various essences and laudanum were also among the many curative agents employed by Paracelsus. The reckless manner in which some of his followers used metallic preparations in their medical practice caused much trouble and discussion, and finally edicts against the use of such substances were issued. But even some of the adherents of the new school, that is to say, the school of Paracelsus, did not fail to per- ceive that there was not a little in the teachings of their master that might be discarded to advantage. Two notable men of this class were Croll and Van Mynsicht, the latter of whom intro- 143 duced tartar emetic into pharmaceutical practice. Croll first made use of sulphate of pot- ash and ere long the alkaline salts came to be of great importance in medicine. Among those employed were the chloride and the carbonate of potash ; the sul- phate of sodium — Glauber's salt, as it is^ now generally termed — was then desig- nated as sal mirabile and was greatly prized by physicians on account of its valuable properties. The medicaments used gradually increased in number ; nitrate of silver, various salts of acetic acid, salt of sorrel, acid juices of fruits, benzoic and succinic acids and man>^ other substances were tried and added to the stores of pharmacy. Spirits of wine,, the aqua vitae of the alchemists, was turned to new account in the preparation of tinctures and of various essences. Valerius Cordus, a German physician, is said to have been the first to make ether from alcohol by means of sulphuric acid. Within the past decades the skill of the pharmaceutical chemist has been directed to the discovery and the pre- paration of remedies which are not found in Nature, as well as to the synthetic 144 manufacture of many drugs which she does offer. The introduction of chloral hydrate, salicylic acid and antipyrin pro- bably inaugurated this new departure ; to-day there are known long lists of h3^pnotics, narcotics and antipyretics that claim coal-tar or similar materials as their parent-substance. Certain glands and other organs of animals are alsO' made to yield preparations which find valued application in the correction of some of ' ' the ills that flesh is heir to. ' ' One of the important lines of investi- gation lately entered upon in pharma- ceutical chemistry is the attempt to trace the relation between the chemical com- position of drugs and their physiological action. Some advances in this direction have even now been made ; what vast and far reaching consequences would follow the solution of this problem, the fulfillment of this day-dream of more than one eminent physician and chemist,, can hardly be foretold. It would cer^ tainly mark a new era in the history of the practice of medicine. During the second half of the last, and the earlier years of this century, the pharmaceutical profession was charged with the keeping of the best interests of 145 chemistry, through fostering the growth, and development of many of its eminent _ disciples. In this connection one need- but recall the names of Scheele, Vauque^ lin and Klaproth ; many others might easily be added to the list. Among the institutes of pharmacy of note in their time, the Trommsdorff Institute, estab- lished in 1795 at Erfurt, perhaps deserves^ special mention. Toxi- It was a sad, but perhaps an unavoid- and ^t)le outcome of conditions that an. Legal increasing knowledge of the potent istry powers inherent in many drugs and chemical preparations should have led to occasional abuse and to their applica- tion for criminal purposes. A recital merely of crimes which have passed into history and which have been executed by the aid of poisons, w^ould form a long and thrilling tale. But the advances made in analytical chemistry have for- tunately made it possible for the science herself to be the Nemesis of those who misuse her gifts to further unlawful designs. Toxicology, which embraces a knowl- edge of the poisons, their effects and their detection, has of late years met with increased attention and study, and 146 now it would prove rather an exceptional instance where the criminal use of a poison could not be detected and proven. Chemical means and methods are also often employed in other instances to aid justice in tracing crime and in fastening- the charge upon the guilty. The detec- tion of forgeries in documents, the exam- ination of blood and other stains, the determination of fraudulent and injurious adulterants in foods and in drugs, all come properly within the scope of chem- ical investigation and control. The domain of physiological chemistry Medical is broad in scope. Originally its aim P^em- was a study of the various tissues, the fluids and the solid components of the animal organism. Among the early investigators of these problems were Fourcroy, Vauquelin, Chevreul and La- voisier ; the latter giving expression to his belief that the processes of life were chemical in their nature. Methods of analysis adapted to the requirements and calculated to overcome the peculiar difficulties of physiological chemistry were gradually evolved. Notable questions that were elucidated by their aid and through most painstak- ing research were, the composition of 147 bone-matter, the constitution of blood. and the phenomenon of its coagulation, the composition of the gastric juice, of milk and of other secretions of the animal body, including the character and proper- ties of the various constituents of urine. Experimental study of the all-important question of animal nutrition was initiated and conducted by Justus von Liebig ; his investigations and deductions regard- ing metabolism were a revelation to his contemporaries and aided materially in bringing about abandonment of the belief in the mysterious power of the so- called ' ' vital force. ' ' Von Liebig appreciated the different functions of the albumenoids, of protein- and gluten, as tissue and muscle builders, and of the carbohydrates, sugar and starch, and of the fats as heat producers. Since his days the problems of nutrition and the composition of nutrients have never failed to claim the attention of eminent workers. Virt, Pettenkofer, Ranke, Atwater, Wiley, are but a few of those who have enriched physiological chemistry in this particular direction by their labors. When a fair knowledge concerning the chemical composition of the various con- 143 stituents of the animal economy had been gained, investigation was directed into new channels ; study was attempted of the relations which these various sub- stances bear to each other, of the specific functions each has to perform and of the conditions under which these various substances are produced and destroyed. Well-known among the men active in such researches are Preyer, Hoppe- Seyler, Virchow, C. Ludwig, Hammar- sten and Chittenden. The poisons which are formed in de- caying animal matter, the so-called cadaver-alkaloids or ptomaines, w^ere first investigated by Selmi. On account of the highly poisonous character which some of these possess, Brieger named them toxines. When it had been ascertained that toxines of various natures are produced also in the progress of some of the diseases most fatal to human life, great skill and energy were brought to bear upon the seeking of antidotes for these poisons, and in this connection are to be recorded some of the most wonderful achievements of bacteriology and chem- istry — the discoveries leading to the use of the so-called anti-toxines. 149 Here there will be recalled the dis-- covery b}^ lyouis Pasteur of the specific agent by which that most terrible of diseases, hydrophobia, can be mastered ;• the preparation of an anti-toxine with which the ravages of diphtheria have, in many instances, been successfully checked ; the preparation of Koch's serum by which the existence of tuber- culosis in animals can be diagnosed and in consequence of which precautionary measures against the spread of this mal- ady can be taken. The first suggestion of producing unv consciousness, anaesthesia, through the inhalation of gases, is credited to Sir Humphry Davy. At least he was famil- iar to some extent with the properties of laughing-gas — nitrous oxide, as the chemists call it. The anaesthetic property of ether — a substance discovered by Valerius Cor- dus, about 1530 — was commented upon by Paracelsus in 1541. This important matter seems, however, to have been wholly lost sight of, forgotten, until the time when Faraday again called attention to it, three hundred years after ether was first known. The inhalation of this substance as a 150 specific agent for relieving pain seems to have been first considered in October, 1846. At that time W. T. G. Morton, a dentist of Boston, applied to Dr. War- ren, a surgeon of that city, to determine whether the vapor of ether could be used in allaying pain in surgical operations, as Morton had found it would do in den- tal practice. Dr. Warren soon acted upon this sug- gestion and successfully used ether in an operation, in the Massachusetts General Hospital, Morton administering the re- agent to the patient at the time. Shortly afterT\^ards a Dr. C. T. Jackson, of Bos- ton, in conversation with Warren claimed that it was he who had acquainted Morton with the use of this reagent for dental operations. In 1847 an English physician, James Young Simpson, acting on the suggestion of a Mr. Waldie of Liverpool, introduced the use of chloroform as an anaesthetic. The use of anaesthetics on the one hand, and the method of treating wounds antiseptically, introduced by the English surgeon, Sir Joseph Lister, will ever rank among the most brilliant achievements of medical chemistry. The extensive studies of Pasteur on 151 fermentation have opened up the vast field of bacteriology with its wonders of the infinitely small. This topic is foreign to our present quest, but it is vividly called to mind in connection with the latest researches of E. Biichner, Tiibin- gen, who would relegate the phenomena of alcoholic fermentation entirely to chemical action, claiming that this va- riety of fermentation is due, not directly to the growth of the yeast-plant, but to a kind of ferment obtainable there- from. Hygiene, the art of preserving health, has of course profited largely by the revelations of physiological chemistry. Having ascertained the character and the nutrient value of various classes and kinds of food, it was but a short step to seek to safeguard against their adultera- tion, which means, at the very least, a lowering of their normal and proper value. So important a matter has this come to be, that many larger commu- nities maintain special officials for the sole purpose of watching and ensuring the purity of their food-supply. Many diseases can be communicated through the agency of food and drink. Among the diseases which can be so 152 spread are tuberculosis, scarlet and ty- phoid fever and cholera. In former times the ravages of these scourges were almost unchecked until their full course had been run, but since the true cause and character of many of these contagious and infectious diseases have come to be understood — thanks in great part to the findings and teachings of bacteriology, — the aid of chemistry has been invoked to supply remedial and preventive agents. An account of the properties, the uses and the benefits conferred by antiseptics and disinfectants would form a chapter of no slight interest in a detailed history of medical chemistry. As one of the most important and bril- liant researches recently made in physio- logical chemistry there must be noted the endeavor of Professor Leopold Schenk, of Vienna, to influence the sex of human offspring by regulating the diet of the mother. In his method insistence is placed upon the chemical nature of the food consumed and upon the complete combustion of this food in the system ; by means of chemical analysis a careful control is kept as to the regularity and the completeness with which this proceeds. 153 Schenk claims that under certain cir- cumstances male progeny may be pro- cured by aid of the influences which he has indicated ; creation at will of female offspring, he admits, is as yet beyond our ken. If his work bears the test of time and experience, a great advance irr physiology will have been made, and in part through the aid of our science. May we, dare we, hope that Chemistry the Beneficent, at whose shrine we all — knowingly or unknowingly — pay daily tribute and homage, will some time return answer to our pleading and reveal" to us the long-sought secret of Life ? 154 WORKS CONSULTED. Gladstone, J. H. The Metals Used by the Great Nations of Antiquity, A Lecture delivered at the Royal Institution^ 1898. Kopp, H. Geschichte der Chemie, 1843- 1847. Kopp, H. Beitrdge zur Geschichte der Che- mie, 1869. Kopp, H. Die Entwickelung der Chemie in der neueren Zeit^ 1873. ROssiNG, A. Einfilhrung in das Studium der^ theoretischen Chemie^ 1890. RoscoE, H. E., and Schorlemmer, C. A Treatise on Chemistry^ 1878. Sadtler, S. p. a Handbook of Industrial Organic Chemistry, 1891. Schorlemmer, C. (Smithells, A.) The Rise and Development of Organic Chemistry, 1894. Thomson, T. The History of Chemistry, 1830- 1831. Venable, F. p. a Short History of Chemistry, 1894. Von Meyer, E. (M'Gowan, G.) A History of Chemistry f'om Earliest Times to the Pres- ent Day, 1 89 1. WiECHMANN, F. G. Lecture-notes on Theo- retical Chemistry, 1895. 155 INDEX OF NAMES. PAGS 1 763-1 832. Adet, Pierre Auguste 80 5th Century, ^neas Gazaos 19 1490-1555. Agricola, Georg. . .15, 30, 85, no 356-323 B.C. Alexander the Great 11 1850- Am^lineau, E 3 Amnael 3 1775-1836. Ampere, Andr6 Marie 59 384-322 B.C. Aristotle of Stagira, ir, 12, 13, 14, 28, 32, 37 19th Cent'y. Arrhenius, Svante 106 1844- Atwater, Wilbur Olin 148 978-1036. Avicenna 28 1776-1856. Avogadro, Amadeo 59, 70 Azazel 2 1561-1626. Bacon, Francis, of Verulam.36, ^y 12 14-1294. Bacon^ Roger 24 1835- Baeyer von, Adolf 138 1867- Bancroft, Wilder D 106 1641-1709. Barner, Jacob 86 15th Cent'y. Basilius Valentintts 143 1635-1682. Becher, }. J 40, 52 1813-1898. Bessemer, Henry, Sir 11 r 1735-1784. Bergman, Torbern, 42, 43, 53, 80, 93. 94, 99» 1 10, 114 1827- Berthelot, Marcellin Pierre. 5, 108 1748-1822. Berthollet, Claude Louis, 52, 54-5 1779-1848. Berzelius, Jons Jacob . .57, 58, 61, 68, 69, 70, 72, 80, 86, 93, 96, 97, 100, 104, 115 1792-1870. Bischof, Karl Gustav 116 157 PAGE 1728-1799. Black, Joseph 44, 45, 46 1843- Bolton, Henry Carrington. .87, 88 1668-1738. Boerhaave,Hermann.45, 86, 91, 92 19th Cent'y. Boullay, P. fils 72 1627-1691. Boyle, Robert 37, 38, 40, 98 i9lh Cent'y. Brieger 149 1849- Brush, Charles Francis 67 19th Cent'y. Biichner, E 152 Budge, Wallis 108 1707-1788. Buffon de, Jean Louis Leclerc 45 1811-1899. Bunsen, Robert Wilhelm Eberhard 103, 116 1731-1810. Cavendish, Henry, Lord, 44, 49, 54 19th Cent'y. Cannizzaro, S 59 19th Cent'y. Carlisle, Antony 104 Chemmis 7 1786-1889. Chevreul, Michel Eugene . . . 147 1856- Chittenden, Russell Henry . . 149 1847- Clarke, Frank\Vigglesworth,63,78 1843- Classen, Alexander 105 ist Century. Clemens, Romanus 2 Cleopatra 126 1784- Colin, Jean Jacques 136 1827-1894. Cooke, Josiah Parsons 106 -1544. Cordus, Valerius 144, 150 -1609. Croll, Oswald 143, 144 1832- Crookes, William, Sir 68, 106 1 722-1765. Cronstedt, Alexander Fried- rich 93 1766-1844. Dalton, John . . .55, 56, 57, 58, 59, 71, 80 1813-1895. Dana, James Dwight 115 1 809-1882. Darwin, Charles Robert 120 1778-1829. Davy, Humphry,Sir.68, 84,104, 150 460-357 B.C. Democritus of Abdera 11 1818-1881. Deville, H. E. St. Claire .... 117 158 PACK 1842- Dewar, James 139 ist Cen. B.C. Diodorus 15, 109 1780-1849. Dobereiner, Johann Wolf- gang 74 1785-1838. Dulong, Pierre Louis 60 1800-1884. Dumas, Jean-Baptiste Andr^, 63, 70, 72 19th Cent'y. Emmerling 138 Empedocles of Agrigent . . . . 11 i8th Cent'y. Engestroem von, Gustav. ... 93 1804-1869. Erdmann, Otto Linn^ 138 1686-1736. Fahrenheit, Gabriel Dominik 92 1791-1869. Faraday, Michael 69, 150 Faust 26 4th Cent'y. Firmicus, Julius Maternus. . . 5 1755-1809. Fourcroy de, Antoine F., 52,96, 147 1825- Frankland, Edward 62, 76 1818-1897. Fresenius, Carl Remigius ... 98 181 1-1892. Fritzsche, F. W 138 1745-1818. Gahn, Johann Gottlieb 93 1778-1850. Gay-Lussac, Joseph Louis, 58, 59, 105 702-765. Geber 27 1672-173 1. Geoffroy, Elienne Francois, 44, 80 18 16-1856. Gerhardt, Carl 73 1822- Gibbs, Oliver Wolcott. . . 105, 106 1604-1668. Glauber, Johann Rudolph. . . 34 1792- Gmelin, Christian Gottlob . . 97 1788-1853. Gmelin, Leopold 70, 71, 100 1749-1832. Goethe von, Johann Wolf- gang 26 19th Cent'y. Graebe, C 136, 137 19th Cent'y. Guldberg 106 19th Cent'y. Hammarsten, Olof 149 i8th,i9thC. Hare 92 159 1568-1631. Hartmann, Johann «3 1755-1827. Hassenfratz, Jean Henri 80 1743-1822. Hauy, R6n6 Just 115 1685-1766. Hellot, Jean 44 1577-1644. Helmont van, Jean Baptiste,3i, 32, 33 1734-1816. Henry, Thomas 97 Hermes Trismegistos. . .16, 17, 18 Herodotus 108 i8th Cent'y. Higgins, W 56 7th Cent'y. Hiuen-Thsang 127 1621-1698. Hofmann, Jo lann Moritz 84 18 18-1892. Hofmann von, A. \V 135 1660-1742. Hoffmann, Friedrich 45 ab't 1000 B.C. Homer 4, 8 1635-1703. Hooke, Robert 39, 40 1825-1895. Hoppe-Seyler, F 149 Horos 3 nth Cent'y. Hortulanus 16 i8th Cent'y. Howard, Edward 97 1769-1859. Humboldt von, Friedrich Heinrich Alexander. 58 1826-1S92. Hunt, Thomas Sterry 117 Isis 3 j8c5-i88o. Jackson, Charles Thomas . . . 151 7th Cent'y. John of Antioch 4 1829-1896. Kekul6 von Stradonitz, Friedrich August. 77 1859- Kemp, James Furman 117 1824-1887. Kirchoff, Gustav Robert 103 1750-1812. Kirwan, Richard 53, 56 1743-1817. Klaproth, Martin Heinrich, 52, 53, 94, 95, 114, 146 1817-1891. Knop, Wilhelm 138 1843- Koch, Robert 150 160 PAGE 1818-T884. Kolbe, Hermann 73 1817-1892. Kopp, Hermann 16, 19 1630-1702. Kunkel, Johann 24 1831- Landolt, Hans 63 1749-1827. Laplace de, Pierre Simon ... 49 1801-1873. La Rive de, Auguste 114 1807-1853. Laurent, Auguste 72, 73, 138 1743-1794. Lavoisier, Antoine Laurent, 47, 48, 49» 50, 52, 54, 71, 80, 86, 99, 147 _i9th Cent'y. Le Bel, J. A 77, 106 19th Cent'y. Leemans 5 1646-17 16. Leibnitz von, Gottfried Wil- helm 29 1645-1715. Lemery, Nicolaus 43, 86, 99 1810-1884. Lepsius, Karl Richard 109 1540-1616. Libavius, Andreas 34, 85 19th Cent'y- Liebermann, C 136, 137 1803-1873. Liebig von, Justus, 71, 72, 84, 98, 119, 148 1827- Lister, Joseph, Sir 151 1836- Lockyer, Joseph Norman. .. . 103 1816-1895. Ludwig, Carl Friedrich W. . . 149 19th Cent'y. Luckow 105 19th Cent'y* Liipke, Robert 105 1718-1784. Macquer, P. J 44 1645-1679. Mayow, John 39» 4o 19th Cent*y. M^ge-Mouries 129 1834- Mendel^eff, Dimitri Iwano- witsch 74, 75 1830-1895. Meyer von, Julius Lothar 74 1794-1863. Mitscherlich, Eilhard, 61, 97, 115 1852- Moissan, Henri 117, 118 1700-1781. Monceau, Duhamel du, Henri Louis 44, no 19th Cent'y. Morgan de, Jacques 107 J838- Morley, Edward Williams. .. 63 161 PAGE 19th Cent'y. Morley, Henry Forster 87 1737-1816. Morveau de, Guyton 51, 80 1819-1868. Morton, William Thomas Green 151 1848- Muir, Matthew Moncrieff Pattison 87 17th Cent'y. Mynsicht van, Adrian 143 19th Cent'y. Nasini, R 67 Nemesis 146 19th Cent'y. Nencke 138 19th Cent'y. Nernst, Walter 106 1838-1898. Newlands, John A. R 74 1643-1727. Newton, Isaac, Sir 29, 54 1753-1815. Nicholson, William 104 1832- Nordenskjold, Nils Adolf Erik 97 19th Cent'y. Olszewski, Karl 139 Osiris 3 1853- Ostwald, Wilhelm, 63, 89, 105, 106 1493-1541. Paracelsus, 24, 30, 31, 32, 34, 143, 150 1822-1895. Pasteur, Louis 77, 150, 151 1838- Perkin, William Henry 135 1791-1820. Petit, Alexis Therese 60 1818- Pettenkofer von, M. J 148 382-336 B.C. Philip of Macedon 11 429-347 B.C. Plato II 23-79. Pliny, Caius Plinius Secundus, 4, 8, 15, 126 ist Cent'y. Plutarch 6 1841-1897. Preyer, Thierry Wilhelm 149 1733-1804. Priestley, Joseph.. .44, 45, 92, 118 1755-1826. Proust, Joseph Louis 54j 55 1 785-1850. Prout, William 59 » 60, 63 Pthah 4 1813- Rammelsberg,C 116 1852- Ramsay, William 66, 75 162 PAGE 19th Cent'y. Ranke 148 19th Cent'y. Raoult 106 1842- Rayleigh, Lord 75 1683-1756. Reaumur de, Ren6 A. F no 1846- Remsen, Ira 106 -1645. Rey, Jean 38 19th Cent'y. Richards 63 1762-1807. Richter, Jeremias Benjamin, 55. 57, 58 1415-1490. Ripley, Georg 84 1780-1840. Robiquet, Pierre-Jean 136 1833- Roscoe, Henry Enfield, Sir. . 86 1798-1872. Rose, Gustav 97, 1 16 1795-1864. Rose, Heinrich 97 1703-1770. Rouelle, Guillaume Fran9ois . 99 19th Cent'y, Sarasin 117 1742-1786. Scheele, Carl Wilhelm, 42, 43, 99, 146 19th Cent'y. Schenk, Leopold 153 i8th Cent'y. Schliiter, Christoph Andreas no 1834-1892. Schorlemmer, Carl 86 19th Cent'y. Selmi 149 -1646. Sendivogius, Michael 28 4B.C.-65A.D. Seneca, Lucius Annaeus 15 1742-1809. Senebier, Jean 118 1572-1637. Sennert, Daniel 34 Seth 5 19th Cent'y. Seubert, Karl 63 1811-1870. Simpson, James Young 150 19th Cent'y. Smith, Edgar F 105 1660-1734. Stahl, Georg Ernst, 40, 42, 4$, 52,86 1813-1891. Stas, Jean Servais 63, 64 1614-1672. Sylvius, Franz de le Boe . . .31, 34 17th Cent'y. Tachenius, Otto 34 1825-1878. Taylor, Bayard 26 163 PACK 1761-1815. ^Tennant, Smithson 97 150-230. ' Tertullianus ^ 640-550 B.C. Thales 14 4th Cent'y. Themistos Euphrades 19 1777-1857. Th^nard, Louis Jacques 105 1773-1852. Thomson, Thomas 57 42 B.C. -37 A.D.Tiberius, Claudius Nero Caesar 8, 9 1842- Tilden, W. A 135 19th Cent'y. Travers, Morris W 6S 1864- Trevor, Joseph E 107 1849- Tripler, Charles E 140 1776-1850. Troost, Gerard 117 1852- Van*t Hoff, Jacobus Hen- drikus 77, 106 1763-1829. Vauquelin, Louis Nicolas, 53. 96, 114, 146, 147 182 1- Virchow, Rudolf 149 19th Cent'y- Virt 14S 19th Cent'y. Waage 106 19th Cent'y. Waldie 151 1778-1856. Warren, John Collins 151 1815-1884. Watts, Henry S& 1740- 1 793. Wenzel, Carl Friedrich 55 1844- Wiley, Harvey Washington. . 148 1835- Wislicenus, Johannes 77 1800-1882. Wohler, Friedrich, 71, 96, 97, lor 1766-1828. Wollaston, William Hyde, 57, 93 » 9S 18 17-1884. Wurtz, Charles Adolphe. .47, 106 5th Cent'y. Zosimos of Panopolis 2, 4, 6 164 SUBJECT INDEX. PACK Academia del Cimento 92 Acetic acid. .^ 126 Acetylene 114 Aetherin theory 71 Air, an element 11,13 Albumenoids, functions of 14S Alchemistic symbols 79 Alchemists, early writings of 5 Alchemy 16 Alchemy, aims of 21 Alchymia 34, 85 Alkahest 33 Alizarin, synthesis of 136 Alloys Ill Alloys, colors of 19, 121 Aluminium iii Aluminium cup of Tiberius 8 Ammonium cyanate loi Anaesthetics 150 Analysis, chemical 8a Aniline 13S Aniline colors 135 Animal chemistry 99, Animal nutrition 148: Anthracene 136 Anti-phlogistic theory 47 Antiseptics 153, Anti-toxines i49> 165 page: Argon 66, 75 Aristotle, philosophy of. 1 1 Aqua vitae , 144 Assaying 93 Atom, definition of 82 Atomic theory 55 Atomic theory, attacks on 70 Atomic weights and equivalents 62 Atomic weights, determination of 63 Atomic weights table 65 Ausfiihrliches Handbuch der Analytischen Chemie 97 Avogadro's hypothesis 59 Bacon, teachings of 36 Balance, analytical 91 Benzaldehyde 134 Benzoyl 71 Beryllium, discovery of 96 Berzelius, analytical work of 96 Black's research on alkaline carbonates 46 Blow-pipe analysis 93 Bolton's Bibliographies 87 Boyle's investigations 37 Bronze 108, 11 1 Burning glass, combustion effected by 92 Caesium, discovery of 103 Calcium carbide 114 Calx ot metals 41 Carbides 114 Carbohydrates, functions of 148 Carbonic acid, liquefied 131 Carbon-steel ^ . iir Carborundum 114 166 PAGR Catalogue of Scientific Periodicals 87 Cellulose 132 Chemia 6 Chemical analysis 88 Chemical combination, views on 54 Chemical equations 83 Chemical equivalents 61 Chemical knowledge, early 7 Chemical nomenclature 80 Chemistry, early instruction in 84 Chemistry, language of 78 Chemistry, manuals of 84 Chemistry of the stars 103 Chemistry of Three Dimensions 78 Chemistry, oldest manuscript on 4 Chemistry, origin of 2 Chemistry, origin of the term 5 Chloroform 151 Chlorophyll 123 Chromium, discovery of 96 Chro7iicles of John of Antioch 4 Chymia Philosophica 86 Cinnabar no Coal-tar colors 135 Coins, earliest 108 Color of leaves 123 Combustion-theory 39 Compound of Alchyynie 84 Compounds, symbols of 82 Coniferin 134 Conjugate compounds 73 Constitution of metals, alchemists' view of. 25 Copper, early use of 108 Copper-coating of vessels 112 Coronium 67 167 PACK Cours de Chymie , ,86, 99. Crucibles, silver 96 Cumarin 134 Cup ofTiberius 8 Dalton's atomic theory. . . . i 56 Democritus' primal form of matter 11 Dephlogisticated air 49 De re tnetallica 30, 85 Diamond, composition of 97 Diamond, synthesis of. 117 Didactic chemistry 83 Dictionary of Chemistry 86 Diseases communicable through food 152 Disinfectants 153 Docimacy 94 Drugs, relation between composition and action 145 Drugs, synthesis of 145 Dualistic theory 69 Dulong and Petit's law 60 Dyeing, early knowledge of 9 Dyads, definition of 62 Early systems of natural philosophy 10 Earth, an element iii 13 Earth-worms 120 Egypt, the home of alchemy 16 Egyptian symbol of immortality 154 Electro-chemical theory 68 Electro-chemistry 104 Electrolysis of chemical compounds 104 Electro-metallurgy 113 Electro-plating 114 Electrum 108 168 pack: Elemenia Chemiae 86- Elements de Chimie 86 Elements, newly discovered 66 Elements, symbols of 82 Elixir, great and small 22 Embalming, early practice of. 9 Emerald tablet, the 17 Equations, chemical 83 Equivalents, Gmelin's table of 71 Era of quantitative investigation 52 Essential oils, synthesis of 134 Ether 144, 150 Etherion 68 Faraday's law 69 Fermentation 152 Fertilizers 122 Fire, an element 11, 12 Fixed air 46 Food adulteration 152 Food, synthesis of 129 Food-tablets 130 Formulae, chemical 82 Fimdameyita Chemiae 86 Gallium, discovery of 75, 103 GaZ'sylvestre ... :i^2> Geological chemistry 116 Germanium, discovery of 75 Glass, manufacture of 9, 125 Glauber's salt 144 Gmelin's table of equivalents 71 Gold, early use of 107 Gold, philosophers* 23 Gold, supposed constituents of 25 169 PAGE Golden fleece 4 Gravimetric analysis 90 Handbuch der Miner alchemie 116 Hare's hydrogen apparatus 92 Helium, discovery of 66, 75 Henoch 2 Hermetic art 21 Historia naturalis 4 Homilies 2 Hooke and Mayow's theory of combustion. 39 Humus-doctrine 119 Hygiene 152 latro-chemistry 30 Idria, mercury mines of no Immortality, Egyptian symbol of. 154 Indestructibility of matter 32 India rubber, artificial 133 Indigo, synthesis of. 137 Indium, discovery of 103 Indol 138 Inorganic and organic substances ico IntroductioJi to Chemical Analysis 96 Iridium, discovery of 97 Iron, Bergman's investigation of no Iron, early use of 109 Isis and Osiris 6 Isomorphism 61, 115 Isoprene 134 Journal of Physical Chemistry 106 Klaproth's work 94 Koch's serum 150 Krypton, discovery of 66 170 PAGB Lamps, perpetually burning 27 Language of chemistry 78 Lapis lazuli 138 Laudanum, early use of 143 Laughing gas 150 Lavoisier's work 47 Law of Dulong and Petit 60 Law of volumes/ 58 Leaves, color-changes of. 123 Legal chemistry 146 Lehrbuch der Chemie 86 Lehrbuch der Chemischen Geologie 116 Lemery's classification 99 Leyden papyrus 4 Liquid air 139 Madder 136 Magisterium, the great 21 Manuals of chemistry 84 Manuscript, oldest, on chemistry 4 Mathesis 5 Matter, Aristotle's primary qualities of 12 Matter, indestructibility of 32 Mauve 135 Mead 10 Medical chemistry 147 Mendel^efTs predictions 75 Mercury of the alchemists 25 Metal calxes 41 Metallic pigments 113 Metallurgical chemistry 107 Metals, transmutation of 19, 21 Metargon, discovery of 66 Meteorites, diamonds in 117 Meteorites, early analyses of 97 171 PAGE Micrographia 39 Mineralogical chemistry 114 Mineralogy, synthetic 116 Monads, definition of 62 Monium, discovery of 68 Mordants, early use of 125 Nagada, tomb at 107 Natural philosophy, early systems of 10 Neon, discovery of .... 66, 75 New System of Chemical Philosophy. . . 57 Nitrous oxide 150 N®menclature, chemical 80 Nucleus theory 72 Nutrition, animal 148 Oleomargarine 129 Organic analysis and synthesis 98 Organic and inorganic substances 100 Origin of alchemy 16 Origin of chemistry 2 Origin of the word chemistry 5 Oiiris, tomb of 3 Osmium, discovery of 97 Oriim philosophicum 23 Oxygen, term first used 49 Panacea, the great 27 Papyrus of Leyden 4 Perfumes, synthesis of 135 Period of transition 36 Periodic law 73 Periodicity of properties 76 Perpetually burning lamps 27 Pharmaceutical chemistry 142 172 PAGE Philosopher's gold 23 Philosopher's stone, descriptions of 24 Philosopher's stone, manufacture of 22 Philosophers stone, powers of 26 Philosophy of Aristotle 11 Phlogiston theory 40 Phlogiston theory, decadence of 45 Physical chemistry 106 Physiological chemistry 147 Phyto-chemistry ... i iS Platinum, refining of. 93 Potassium, discovery of 104 Proust's investigations 54 Prout's hypothesis 59 Proxmiate analysis 89 Ptomaines 149 Qualitative analysis 90 Quantitative analysis 90 Quantitative investigation, era of 52 Quantivalence 62 Quartz changed into gems 28 Quartz formed from water 15 Radicals 100 Radicals, theory of 71 Raven's head 23 Rubidium, discovery of 103 Saccharin 1 28 Sal maris 78 Sal mirabile 1 44 Salt, definition of 34 Scandium, discovery of 75 Sceptical Chymist^ The 39 J 73 PAGB Scheele's investigations 43 Schenk's theory 153 Scholastics, teachings of 13 Scientific Foundations of Analytical Chem- istry ^ 89 Select Bibliography of Chemistry 87 Silicides 114 Silk, artificial 132 Silver, early use of. 107 Silver crucibles 96 Silver rings 108 Soaps, early use ol 125 Sodium, discovery of 104 Specific heat 60 Spectrum analysis 102 Spirits of wine 144 Spread of alchemy 20 Steel, Bessemer's process iii Steel, R^amur's process no Stereo-chemistry 77 Stoichiometry, foundations of , 55 Stone-honey 127 Strontium, discovery of. 105 Substitution theory 72 Sugar 126 Sulphate of potash 144 Sulphate of sodium 144 Sulphur, early use of 126 Sulphur of the alchemists 25 Swan, the 24 Symbols, alchemistic 79 Symbols, systems of chemical 80 Synthesis of food 129 Synthesis of water 50 Synthetic mineralogy 116 174 PAGE System of Chemistry 57 Table of atomic weights 65 Tabula sinaragdina 16 Teachings of scholastics 13 Technological chemistry 124 Temperature, measurement of .... 91 Terra pinguis 41 Text-book of Mineralogy 116 Thallium, discovery of. 103 Thermometer, construction of. 91 Thomas-Gilchrist process iii Tiberius, cup of 8 Tincture, the red 21 Tincture, the white 22 Tomb of Osiris 3 Toxicology 146 Toxines 149 Transition, period of. 36 Transmutation of metals 14, 19 Treatise on Chemistry 86 Triads, definition of 62 Trommsdorff Institute 146 Types, theory of 73 Ultimate analysis 89 Ultramarine 138 Unitary theory 72 Universal solvent 33 Urea, synthesis of loi Valence 61 Vanillin 134 Vital air 49 Vital force loi 175 PAGE Volumetric analysis 90 Water, an element 11. 13, 14, 32 Water, electrolysis of 104 Water, synthesis of 50 Water, transmutability of 15 Wet analysis 94 Woad 137 Xenon, discovery of 67 Zeitschrift fuer Analytische Chemie 98 Zeitschrift fuer Physikalische Chemie 106 176