The foundation stones of empirical discovery, upon which this science is based, had been crudely shaped by the workmen of preceding centuries, but the classification and laying of them into the structure of an exact science is the work of the Nineteenth Century. The glass of the Phoenicians, and the dyes and metallurgical operations of the Egyptians, involved some chemical knowledge; much more did the operations of the alchemists, who vainly sought to convert the baser metals into gold, but these were only the crude building stones, out of which the great complex modern structure has been raised. In the Sixteenth Century the study of chemistry, apart from alchemy, began, and some attention was given to its application to the uses of medicine. Aristotle’s four elements—fire, air, earth and water—were no longer accepted as representing a correct theory, and new ones were proposed only to be found as erroneous, and to be superseded in time by others.Briefly traversing the more important of the earlier steps, there may be mentioned the phlogiston theory of Stahl in the earlier part of the Eighteenth Century; the discovery of the composition of water by Cavendish in 1766; of oxygen by Priestly and Scheele in 1774; the electro-chemical dualistic theory of Lavoisier in the latter part of the Eighteenth Century, followed by a rational nomenclature established by Guyton de Morveau, Berthollet and Fourcroy; the doctrine of chemical equivalents by Wenzel in 1777 and Richter in 1792; Dalton’s atomic theory; Wollaston’s scale of chemical equivalents; Gay Lussac’s law of combining volumes; Berzelius’ system of chemical symbols and theory of compound radicals; contributions of Sir Humphrey Davy and Faraday in electro-chemistry, and Thenard’s grouping of the metals. These interesting phases of development of the old chemistry have been followed by the new theory of substitution, by Dumas and others. This change, beginning about 1860 and running through a period of nearly twenty years, has gradually supplanted the old electro-chemical dualistic theory and established the present system.

Among the important and interesting achievements of chemistry in the Nineteenth Century is the artificial production of organic compounds. All such compounds had heretofore been either directly or indirectly derived from plants or animals. In 1828 Wohler produced urea from inorganic substances, which was the first example of the synthetic production of organic compounds, and it was for many years the only product so formed. Berthelot, of Paris, by heating carbonic oxide with hydrate of potash produced formiate of potash, from which formic acid is obtained; by agitating olefiant gas with oil of vitriol a compound is produced from which, upon the addition of water and distillation, alcohol is formed; he also re-combined the fatty acids with glycerine to form the original fats.

In the classification of this science, it has been divided into inorganic chemistry, relating to metals, minerals and bodies not associated with organic life, and organic chemistry, which was formerly limited to matter associated with or the result of growth or life processes, but which is now extended to the broader field of all carbon compounds. In later years the most remarkable advances have been made in the field of organic chemistry. The four elements carbon, hydrogen, oxygen and nitrogen have been juggled into innumerable associations, and in various proportions, and endless permutations, have been combined to produce an unlimited series of useful compounds, such as dyes, explosives, medicines, perfumes, flavoring extracts, disinfectants, etc.The most interesting of these compounds are the coal tar products. Coal tar, for many years, was the waste product of gas making. Forty years ago about the only use made of it was by the farmer, who painted the ends of his fence posts with it to prevent decay, or by the fisherman, who applied it to the bottoms of his boats and his fishing nets. To-day the black, offensive and unpromising substance, with magical metamorphosis, has been transformed by the chemist into the most beautiful dyes, excelling the hues and shades of the rainbow, the most delightful perfumes and flavoring extracts, the most useful medicines, the most powerful antiseptics, and a product which is the very sweetest substance known. The aniline dyes represent one of the great developments in this field. In 1826 Unverdorben obtained from indigo a substance which he called “Crystalline.” In 1834 Runge obtained from coal tar “Kyanol.” In 1840 Fritzsch obtained from indigo a product which he called “Aniline,” from “Anil,” the Portuguese for indigo. Zinin soon after obtained “Benzidam.” All these substances were afterward proved to be the same as aniline. Perkins’ British patent, No. 1,984, of 1856, is the first patented disclosure of the aniline dyes, and represents the beginning of their commercial production. This combines sulphate of aniline and bichromate of potash to produce an exquisite lilac, or purple color. The first United States patent was in 1861, and now there are about 1,400 patents on carbon dyes and compounds, the most of which belong to the coal tar group. In dyes artificial alizarine, by Graebe and Lieberman (Pat. No. 95,465, Oct. 5, 1869); aniline black, by Lightfoot (Pat. No. 38,589, May 19, 1863); naphthazarin black, by Bohn (Pat. No. 379,150, March 6, 1888); artificial indigo, by Baeyer (Pat. No. 259,629, June 13, 1882); the azo-colors, by Roussin (Pat. No. 210,054, Nov. 19, 1878); and the processes for making colors on fibre, by Holliday (Pat. No. 241,661, May 17, 1881), are the most important. The artificial production of salicylic acid, by Kolbe (Pat. No. 150,867, May 12, 1874), marks an important step in antiseptics. Artificial vanilla, by Fritz Ach (Pat. No. 487,204, Nov. 29, 1892), represents flavoring extracts; and artificial musk, by Baur (Pat. No. 536,324, March 26, 1895), is an example of perfumes. In medicines a great array of compounds has been produced, such as antipyrin, the fever remedy, by Knorr (Pat. No. 307,399, Oct. 28, 1884); phenacetin, by Hinsberg (Pat. No. 400,086, March 26, 1889); salol, by Von Nencki (Pat. No. 350,012, Sept. 28, 1886), and sulfonal by Bauman (Pat. No. 396,526, Jan. 22, 1889). To these may be added antikamnia (acetanilide), the headache remedy, and saccharin, by Fahlberg (Pat. No. 319,082, June 2, 1885), which latter is a substitute for sugar, and thirteen times sweeter than sugar. Among the more familiar products of coal tar or petroleum are moth balls, carbolic acid, benzine, vaseline, and paraffine.In the commercial application of chemistry the work of Louis Pasteur in fermenting and brewing deserves special notice as making a great advance in this art. His United States patent, No. 141,072, July 22, 1873, deals with the manufacture of yeast for brewing.The manufacture of sugar and glucose from starch is an industry of great magnitude, which has grown up in the last twenty-five years. Water, acidulated with ¹/₁₀₀th part of sulphuric acid, is heated to boiling, and a hot mixture of starch and water is allowed to flow into it gradually. After boiling a half hour chalk is added to neutralize the sulphuric acid, and when the sulphate of lime settles the clear syrup is drawn off, and either sold as syrup, or is evaporated to produce crystallized grape sugar, which latter is only about half as sweet as cane sugar. Glucose syrup, however, has largely superseded all other table syrups, and is extensively used in brewing, for cheap candies, and for bee food. Our exports of glucose and grape sugar for 1899 amounted to 229,003,571 pounds, worth $3,624,890.

An important discovery, made in 1846, was that carbohydrates, such as starch, sugar, or cellulose, and glycerine, when acted upon by the strongest nitric acid, produced compounds remarkable for their explosive character. Gun cotton and nitro-glycerine are the most conspicuous examples. Gun cotton is made by treating raw cotton with nitric acid, to which a proportion of sulphuric acid is added to maintain the strength of the nitric acid and effect a more perfect conversion. Besides its use as an explosive, gun cotton when dissolved in ether has found an important application as collodion in the art of photography. Nitro-glycerine only differs in its manufacture from gun cotton in that glycerine is acted upon by the acids, instead of cotton. Pyroxiline, xyloidine, and celluloid are allied products, which have found endless applications in toilet articles and for other uses, as a substitute for hard rubber.

The applications of chemistry in the commercial world have been in recent years so numerous and varied that it is not possible to do more than to refer to its uses in the manufacture of soda and potash, of alcohol, ether, chloroform, and ammonia, in soap making, washing compounds and tanning, the production of gelatine, the refining of cotton seed and other oils, the art of oxidizing oils for the manufacture of linoleum and oil cloth, the manufacture of fertilizers, white lead and other paints, the preparation of proprietary medicines, of soda water and photographic chemicals, the manufacture of salt and preserving compounds, in the fermentation of liquors and brewing of beer, the preparation of cements and street pavements, the manufacture of gas, and the embalming of the dead.The most interesting and, in many respects, the most important, development of the last twenty-five years has been in electro-chemistry. Electro-chemical methods are now employed for the production of a large number of elements, such as the alkali and alkaline earth metals, copper, zinc, aluminum, chromium, manganese, the halogens, phosphorus, hydrogen, oxygen, and ozone; various chemicals, including the mineral acids, hydrates, chlorates, hypochlorites, chromates, permanganates, disinfectants, alkaloids, coal tar dyes, and various carbon compounds; white lead and other pigments; varnish; in bleaching, dyeing, tanning; in extracting grease from wool; in purifying water, sewerage, sugar solutions, and alcoholic beverages. The present low price of aluminum, reduced from $12 per pound in 1878 to 33 cents now, is due to its production by electrical methods. Among the earliest successful processes is that described in patents to Cowles and Cowles, No. 319,795, June 9, 1885, and No. 324,658, August 18, 1885, in which a mixture of alumina, carbon and copper is heated to incandescence by the passage of a current, the reduced aluminum alloying with the copper. This has now been superseded by the Hall process (Pat. No. 400,766, April 2, 1889), in which alumina, dissolved in fused cryolite, is electrolytically decomposed. Practically all the copper now produced, except that from Lake Superior, is refined electrolytically by substantially the method of Farmer’s patent (Pat. No. 322,170, July 14, 1885). All metallic sodium and potassium are now obtained by electrolysis of fused hydroxides or chlorides (Pats. No. 452,030, May 12, 1891, to Castner, and No. 541,465, June 25, 1895, to Vautin). The production of caustic soda, sodium carbonate, and chlorine by the electrolysis of brine, is carried on upon a large scale, and will probably supersede all other methods. Nolf’s process (Pat. No. 271,906, Feb. 6, 1883), and Caster’s (No. 528,322, Oct. 30, 1894), employ a receiving body or cathode of mercury, alternately brought in contact with the brine undergoing decomposition, and with water to oxidize the contained sodium. Carborundum, or silicide of carbon, is largely superseding emery and diamond dust as an abradant. It is produced by Acheson (Pat. No. 492,767, Feb. 28, 1893), by passing a current of electricity through a mixture of silica and carbon. Calcium carbide, a rare compound a few years ago, is now cheaply produced by the action of an electric arc on a mixture of lime and carbon, as described by Willson (Pats. Nos. 541,137, 541,138, June 18, 1895). Calcium carbide resembles coke in general appearance, and it is used for the manufacture of acetylene gas, for which purpose it is only necessary to immerse the calcium carbide in water, and the gas is at once given off by the mutual decomposition of the water and the carbide.Agricultural chemistry is another one of the practical developments of the Nineteenth Century. A hundred years ago the farmer planted his crops, prayed for rain, and trusted to Providence for the increase; he was not infrequently disappointed, but was wholly unable to account for the failure. To-day the intelligent farmer understands the value of nitrogen, has ascertained how it may be fed to his crops through the agency of nitrifying organisms, or he has his soil analyzed at the Agricultural Department, finds out what element it lacks for the crop desired, and in chemically prepared fertilizers supplies that deficiency. The chemical analysis of drinking water has also contributed much to the knowledge of right living and to the avoidance of disease and death, which our forefathers were accustomed to regard as dispensations of Providence.

America has furnished some eminent chemists in the Nineteenth Century, who have made valuable contributions to the science, notably in the field of metallurgy. It is a fact, however, which must be admitted with regret, that America has not in the field of chemical research occupied the leading place she has in mechanical progress. The European laboratory is the birthplace of most modern inventions in the chemical field, and this is so simply by reason of the fact that these more patient investigators have set themselves studiously, systematically and persistently to the work of chemical invention. It is said that some of the large commercial works in Germany have over 100 Ph. D.’s in a single manufacturing establishment, whose work is not directed to the management of the manufacture, but solely to original research, and the making of inventions. The laboratories in such works differ from those in the universities only in being more perfectly equipped, and more sumptuously appointed. The result of this is seen in the fact that in 1899 the United States imported coal tar dyes alone to the extent of $3,799,353, and 5,227,098 pounds of alizarine, most of which came from Germany, and for which we paid a good price, since the German manufacturers control the United States patents. The alizarine dyes are for the most part the artificial kind made by German chemists. Prior to 1869 the red alizarine dye was of plant origin, being obtained from madder root, and it cost $2 a pound. The German chemist produced an artificially made product, which took the place of the madder dye, and was sold at $1.20 a pound. At the end of the patent term (seventeen years) the price fell to 15c. a pound, showing that the product was produced at a profit of more than $1.05 a pound, and as millions of pounds were imported annually, it is estimated that $35,000,000 was the price paid the German chemists for their foresight in combining science with business. Many United States patents granted to foreign chemists are still in force, and the rich reward of their skill is reaped at our expense.Discovery of elements.—In the early days of chemical knowledge, fire, air, earth and water constituted the insignificant category of the elements, which was as faulty in classification as it was small in size. Gradual splitting up of compounds, and an increase in the number of elements, has gone on progressively for some hundreds of years, until to-day the list extends well on to one hundred elementary bodies. Those which belong to the credit of the Nineteenth Century are given in the table following, with the name of the discoverer, and the date of its discovery.

Whether or not these so-called elements are really true elementary forms of matter, which are absolutely indivisible, is a problem for the chemists of the coming centuries to solve. The classification has the approval of the present age. What new elements may be found no one may predict. Mendelejeff’s periodic law, however, suggests great possibilities in this field. Allotropism, in which the same element will present entirely different physical aspects, is also a significant and suggestive phenomenon, for in it we see carbon appearing at one time as a crude, black and ungainly mass of coal, and at another it appears as the limpid and flashing diamond. In more than one mind there is a lurking suspicion that there may, after all, be only one form of primordial matter, from which all others are derived by some wondrous play of the atoms, and if so the old idea of the alchemist as to the transmutation of metals may not be entirely wrong. The Twentieth Century may give us more light.