Page:Encyclopædia Britannica, Ninth Edition, v. 5.djvu/476

Rh 464 CHEMISTRY [HISTORY. la 177G Lavoisier, by experiments with phosphorus and sulphur, confirmed results already arrived at by him that the atmosphere contained two gases, azote or nitrogen, and a highly respirable air, the absorption of which by burning substances accounts for their increase in weight. In 1777 he combated the assertion of Priestley that air is rendered irrespirable by becoming loaded with phlogiston, and showed that air in which candles were burnt furnished about two-fifths of its volume of fixed air, and that pure or dephlogisticated air under the same conditions became almost completely transformed into that gas. In a paper received by the Academy in ]778 Lavoisier broached his theory that the dephlogisticated air of Priestley was the universal acidifying or oxygenizing principle, which by combination with charcoal, sulphur, nitrogen, and phosphorus formed carbonic, vitriolic, nitric, and phosphoric acids, and with metals, calces ; all the phenomena of com bustion, Lavoisier contended, were explicable without the supposition of the existence of phlogiston, of which there was no evidence. In 1783, when he had determined to discover by carefully conducted experiments the nature of the product of the combustion of hydrogen, Lavoisier learned that Cavendish had ascertained that body to be water. He therefore repeated Cavendish s experiments, and with the aid of Meusnier proved that water con tains hydrogen, by passing steam through a red-hot porcelain tube containing iron wire. Lavoisier had long been unable to hold the doctrine that hydrogen was the phlogiston of metals, seeing that the calces were actually heavier than the metals supposed to contain them, and that the hydrogen supposed to be evolved by the metals, though light, certainly had weight. Lavoisier now explained the production of hydrogen during the solution of metals in acids on the assumption that water was decomposed, its oxygen uniting with the metals, whilst its hydrogen escaped. In the case, however, of nitric acid, oxygen was supposed to be supplied by the acid. The effect of Lavoisier s reasonings upon his contemporaries is illustrated by Priestley s remark (Phil. Trans., 1788, p. 155) that, &quot;the doctrine of the decomposition of rvater being set aside, that of pldogiston (which in consequence of the late experiments on water has been almost universally abandoned) will much better stand its ground.&quot; But the fate of the Stahlian philosophy was sealed ; and in 1792 Klaproth and the Berlin Academy gave in tiieir adhesion to the new doctrines. Gren and Wiegleb in Germany, Uelametherie in France, and Kirwan in England endea voured but in vain, to support the phlogistic theory; and ere long Lavoisier s innovations could be regarded not simply as the anti-phlogistic, but as the universally accepted system of chemistry. &quot; It was the glory of Lavoisier,&quot; wrote Davy in 1814, &quot;to lay the foundation of a sound logic in chemistry by showing that the existence of this principle (phlogiston), or of other principles, should not be assumed where they could not be detected.&quot; In 1789 was published Lavoisier s Traite tlementaire de Chimie, in which the new chemical doctrines were set forth with remarkable clearness and ability. A list of 33 &quot; simple substances &quot; is given in the 2d part of the 1st vol. of this work, wherein light and caloric are included with oxygen, azote, and hydrogen as elements of bodies ; but as to whether light was a modification of caloric, or caloric a modification of light, it was impossible, Lavoisier considered, to decide (Traite element., torn. 1. part ii. chap. 1). Under the head of &quot; oxidable or acidifiable substances &quot; he placed sulphur, phosphorus, carbon, and the muriatic, fluoric, and boracic radicals ; the &quot; oxidable and acidifiable metals &quot; are antimony, silver, arsenic, bismuth, cobalt, copper, tin, iron, manganese, mercury, molybdenum, nickel, gold, platinum, lead, tungsten, and zinc ; and the &quot; simple earthy and salifiable substances &quot; are lime, magnesia, baryta, alumina, and silica. Of metallic oxides, he says (Traite element., torn. i. part i. chap, vii.), &quot;they ought not to be considered as completely saturated with oxygen, because their action on that principle is balanced by the force of attraction exercised upon it by caloric. Oxygen, then, in the calcination of metals, obeys really two forces that exercised by the caloric and that exercised by the metal.&quot; Davy, who by his experiments on the effects of friction on ice did much to dispel the belief in the materiality of heat, but who regarded light as a body in a peculiar state of existence, and consisting of minute particles, held the view that light in phosoxygen (oxygen gas) was intimately combined with oxygen. ( Works, vol. ii. pp. 11-32.) The following table will serve to show the progress that has been made in the knowledge of the elementary bodies from the time of the publication of Lavoisier s Traite elementaire ; the second and third columns give the authori ties by whom and the dates when these bodies were eithei first isolated, or were recognized as simple substances : Uranium Klaprotli 1789 Strontium Davy 1808 Titanium Klapreth 1795 Chlorine Duvy 1810 Chromium Vauquelin 1797 Fluorine Ampere 1810 Tellurium Klaprotli 1798 Iodine Courtois 1811 Tantalum (Hatchett &amp;lt;t) Ekeburg ) 1801 1802 Lithium Selenium Arfvedson Berzelius 1817 1817 Vanadium (Del Rio and) (Sefstrom j 1801 1830 Cadmium ( Hermann &^ (Stromeyer j 1818 Cerium ( Berzelius, ) -JHlslnger, *&amp;gt; ( Klaproth ) 1803 Silicon Zirconium Bromine Berzelius Berzelius Balard 1823 1824 182fi Palladium Iridium Wollaston Tennant 1803 1804 Aluminium) Glucinum j Wiihler -j 1827 1828 Osmium Tennant 1804 Thorium Berzelius 1828 Rhodium Wollaston 1804 Yttrium Wiihler 1828 Potassium) Sodium ) Davy 1807 Didymium ) Lanthanum)&quot; Mosander 1841 (Davy, and) Erbium Mosander 1843 Barium (Berzelius &amp;lt;fcy 1808 Niobium Rose 1844 (Pontin ) Ruthenium Claus 1844 Boron (Davy, and k &amp;lt; Gay-Lussac &amp;gt; 1808 Caesium ) Rubidium ) (Kirchhoff & (Bun sen 18GO 18fil (& The iiard ) Thallium -1 Crookes 18C1 Calcium I Davy, and ) -&amp;lt; Berzelius & V (Pontin ) 1808 Indium and Lamy (Reich and) (Richter / 1862 1863 Magnesium Davy 1808 Gallium Boisbaudran 1875 Lavoisier was assisted in the establishment of his system by Fourcroy (1755-1809), Monge (1746-1818), Guyton de Morveau (1737-1816), and Berthollet (1748-1822); Lavoisier s theory that oxygen was the principle of acidity was not, however, accepted by Berthollet. In 1803 appeared Berthollet s Chemical Statics, in which Bergman s conclusions with respect to the laws of the combination of acids and bases were disputed. Affinity, it was argued, could not &quot;be simply an attraction, for then no decomposition, but only art addition of constituents would take place when solutions of different compounds were mixed together ; affinity might be regarded as an attraction between combining substances probably like that existing between the planetary bodies an attraction dependent on mass, not on elective force, so that com bination between the various kinds of matter could take place in all sorts of proportions. The complete removal of a constituent of a compound by means of a decomposing agent was attributed by Berthollet to its elasticity or insolubility in the free state. Thus, he considered that barium sulphate was precipitated by solution of potassium sulphate because it was insoluble in water, but that a triple compound was formed when solutions of the sulphates of sodium and potassium were mingled. The decomposition of ammonium carbonate by sulphuric acid he asserted to be due to the elasticity of the carbonic acid gas that escaped, Berthollet s hypotheses found an opponent in Proust (1755-1826), who had already written on the constancy of the relations by weight of the component parts of bodies, and had shown that tin and antimony unite with oxygen,