Page:The New International Encyclopædia 1st ed. v. 04.djvu/651

* CHEMISTRY. 569 CHEMISTRY. use of the l)a lance, are due to the founder of quantitative cliemistry — the French physi- cist and clieniist Lavoisier. But before we proceed to narrate the further progress of clieniical philosopliy, it remains to enumerat* briefly the most important achieve- ments of cliemical technology during the reign of phlogiston. In spile of its fun<lamontal error, chemistry was making fairly rapid progress, and this naturally told on tlic industries. Boyle and Kunkel improved many metallurgical processes and the manufacture of glass. The manufacture of iron and steel owed valuable improvements to the researches of Bergman, Gahn, Rinman, and Reaumur. Stahl, Scheele, Hellot, ilacquer, and others introduced new dyestuffs and im- proved many processes of dyeing. The prepara- tion of zinc was improved by Jiarggraff, and its manufacture on a large scale was commenced at Bristol in 174.3. The manufacture of sulphuric acid was conunenced by Ward at Richmond; and in 174(> lead chambers were first introdviced bj' Roebuck. In 1747 llarggrafT discovered sugar in beets; however, the sugar industry was not bom until the beginning of the Nineteenth Century. Early in the Eighteenth Century (1703) Bottger was accidentally led to the invention of porce- lain, and its manufacture conmienced at ^leissen in 1710; but the processes were kept secret, and the manufacture was confined to Meissen until Reaumur rediscovered them by systematic re- search, and finally, in 1769, great porcelain works were established also at Sfevres, near Paris, in the course of the period many substances were introduced as therapeutic agents, and Seheele discovered a number of important compounds of carbon. Modern Chemistry. If. after we have become accustomed to think of modem chemistry as foimdcd in the latter part of the Eighteenth Century, we take up the writings of phlogistic chemists prior to that time, we may be greatly surprised to find that our general principles were not at all unknown to them. They certainly be- lieved in the indestructibility of matter, and some of them described molecules and atoms in much the same way as we describe them at the present day. . d yet their knowledge cannot be rightly considered as constituting a science. Their abstract speculations were very keen; their knowledge of chemical facts vas quite extensive; hut that mathematical correspondence between abstract principles and concrete phenomena which alone constitutes science did not exist. And so, even when the properties of ga.ses were no longer imknown, all chemical knowledge re- mained in a state of confusion, and elements continued to be considered as compounds, com- pounds as elements, combinations a.s decomposi- tions, and decompositions as combinations, until the work of establishing the scientific corre- spondence was begim by Lavoisier. Endowed hy nature with a keenly critical mind. Lavoisier acquired the habit of quantita- tive thinking by early training in mathematics and physics, and by subsequent association with some of the most brilliant mathematicians and physicists of his time. .Xs early as 1770 we find him solving a problem of chemistry by a purely quantitative method. It was known, namely, that when water is kept boiling for some time in a glass vessel, there is formed in it an earthy deposit; it was therefore believed that water could be converted into 'earth.' Lavoisier heat- ed water in a glass vessel, weighed the vessel be- fore and after the operation, and found that the vessel plus the dei)osit after the operation weighed exactly as much as the vessel alone weighed before. He thus proved that the earthy deposit came, not from the water, but from the gla.ss of the vessel. In 177- he turned the same qiianlitative method of experimenting and reasoning to the conversion of metals into calces, and in 1774 published the following observation: When metallic tin is healed in a sealed retort full of air, it becomes transfonned into its calx; the weight of the sealed retort with its contents is exactly the same after the reaction as before; if the retort, is now opened, air rushes into it and the weight is increased; the increase is equal to the difTerence in weight between tlu- calx formed and the mass of metallic tin employed. Krom this Lavoisier concluded that the trans- formation of tin into its cal.x involved the ab- sorption of air, and that phlogiston had nothing to do with the phenomenon. It also became evi- dent to him that the balance of precision could serve the chemist no less than the telescope served the astronomer, and that the principle of indestructibility, which could and should be established experimentally, ought to be at the basis of all chemical reasoning. When Priestley and Scheele discovered oxygen, they thought that it was this constituent of air that was capable of absorbing phlogiston from metals; Lavoisier demonstrated that it was this constituent of air that combined with metals to form calces. He recognized that the same gas combined with sulphur, phosphorus, charcoal, and other com- bustible substances, and as he regarded the result- ing compounds as acids, he gave to the gas the name oxygen (from the Greek b^'ic, oxys, acid, and yfijf, (jencs, producing), and adopted the view that it was an indispensable constituent of all acids (this view was discarded half a century later). Carbonic acid he recognized as a com- pound of carbon and oxygen, and when Caven- dish found that the sole product of the combus- tion of hydrogen in oxygen was water. Lavoisier imderstood that water was not an element, but a compound of hydrogen and oxygen, and had no difficulty in determining its quantitative com- position. Carbonic acid and water he also showed to be the products of the combustion of organic substances, and soon he recognized that respira- tion, too, was a process of organic combustion. Logical and consistent as Lavoisier's method appears to the unprejudiced mind, it failed to appeal to some of the most eminent men of his time. Thoroughly accustomed to the inverted principles of the phlogistic doctrine, those men adhered to them as firmly as fanatics will ad- here to an absurd creed, and some of them, in- cluding Priestley, himself the discoverer of oxj'- gen. died l)elievers in phlogiston. Nevertheless, Lavoisier lived to see the light of his system spread over the entire scientific world, and turn chaos into order. He had established a rigid correspondence between the law of inde- structibility and chemical transformations, and bad thus built the first bridge between an ab- stract principle and the world of chemical phe- nomena. The concept rlrmrnt was now correctly applied to oxygen, hydrogen, carbon, sulphur, phosphorus, and the metflls then known in the free state; the concept compound was correctly