OXYGEN (symbol O, atomic weight 16), a non-metallic chemical factor. It was apparently first obtained in 1727 by Stephen Hales by strongly heating minium, but he does not appear to have recognized that he had obtained a brand new element, and the first revealed description of its properties was on account of J. Priestley in 1774, who obtained the fuel by igniting mercuric oxide, and gave it the name "dephlogistigated air." K. W. Scheele, working independently, additionally announced in 1775 the discovery of this component which he called "empyreal air" (Crells’ Annalen, 1785, 2, pp. 229, 291). A. L. Lavoisier repeated Priestley’s experiments and named the gasoline "oxygen" (from Gr. Oxygen happens naturally as one of the chief constituents of the atmosphere, and in combination with different components it's found in very massive quantities; it constitutes roughly eight-ninths by weight of water and nearly one-half by weight of the rocks composing the earth’s crust. It's also disengaged by growing vegetation, plants possessing the ability of absorbing carbon dioxide, assimilating the carbon and rejecting the oxygen.

Oxygen may be ready by heating mercuric oxide; by strongly heating manganese dioxide and plenty of different peroxides; by heating the oxides of precious metals; and by heating many oxy-acids and oxy-salts to high temperatures, for instance, nitric acid, sulphuric acid, BloodVitals nitre, lead nitrate, zinc sulphate, potassium chlorate, &c. Potassium chlorate is generally used and the response is accelerated and carried out at a decrease temperature by beforehand mixing the salt with about one-third of its weight of manganese dioxide, which acts as a catalytic agent. The precise decomposition of the chlorate isn't settled positively; the next equations give the outcomes obtained by P. F. Frankland and Dingwall (Chem. News, 1887, 55, p. 67):-at a average heat: 8KClO3＝5KClO4＋3KCl＋2O2, succeeded by the next reactions because the temperature will increase: 2KClO3＝KClO4＋KCl＋O2 and 2KClO3＝2KCl＋3O2 (see also F. Teed, ibid., 1887, 55, p. 91; H. N. Warren, ibid., 1888, 58, p. 247; W. H. Sodeau, Proc. Chem Soc., 1901, 17, p.

149). It may also be obtained by heating manganese dioxide or potassium bichromate or potassium permanganate with sulphuric acid; by the motion of cobalt salts or manganese dioxide on a solution of bleaching powder (Th. Fleitmann, Ann., 1865, 134, p. 64); by the motion of a ferrous or manganous salt with a salt of cobalt, nickel or copper on bleaching powder (G. F. Jaubert, Ger. pat. 157171); by passing chlorine into milk of lime (C. Winkler, Jour, prakt. Chem., 1866, 98, p. 340); by the motion of chlorine on steam at a brilliant pink heat; by the decomposition of hydrogen peroxide by bleaching powder, manganese dioxide, potassium ferricyanide in alkaline resolution, or potassium permanganate in acid answer; by heating barium peroxide with an aqueous answer of potassium ferricyanide (G. Kassner, Zeit. angew. Chem., 1890, p. 2＋O2; by the decomposition of sodium and potassium peroxides with a solution of potassium permanganate within the presence of a trace of nickel salts (G.

F. Jaubert, Comptes rendus, 1902, 134, BloodVitals p. Numerous methods have been devised for the manufacture of oxygen. The extra necessary are as follows: by decomposing strongly heated sulphuric acid within the presence of a contact substance; by heating an intimate mixture of one a part of sodium nitrate with two elements of zinc oxide (T. H. Pepper, Dingler’s Jour., 1863, 167, p. 39): 2ZnO＋4NaNO3＝2Zn(ONa)2＋2N2＋5O2; by means of cuprous chloride which when blended with clay and sand, moistened with water and heated in a present of air at 100-200° C. yields an oxychloride, which latter yields oxygen when heated to 400° C (A. Mallet, Comptes rendus, 1867, 64, p. 226; 1868, 66, p. 349); by the electrolysis of solutions of sodium hydroxide, utilizing nickel electrodes; by heating calcium plumbate (obtained from litharge and calcium carbonate) in a current of carbon dioxide (G. Kassner, Monit. Scient., 1890, pp. 503, 614); and from air by the technique of Tessié du Motay (Ding.