OXYGEN

n. O2x'i2-je2n. Lat., oxygenium [Belg. Ph., Gr. Ph.] (from of us, acid, and yevvav, to engender). Fr., oxyc/ene. Ger., Sauerstoff. A non-metallic element discovered by Priest ley in 1774, and termed by him dephlogisticated air, its present name being given to it by Lavoisier in 1778. It is a colorle , tastele , and odorle gas, of a sp. gr. of T1056 as compared with that of air, and soluble in water, which takes up about 4 per cent, of it by volume. Under the combined influence of a very low temperature ( 130 C.) and great pre ure (475 atmospheres, or about 3| tons to the square inch) o. is liquefied. Under certain conditions it is converted into ozone. It occurs in the free state in the atmosphere, of which it forms more than one fifth by weight. Combined with hydrogen it forms water, and combined with silicon and the metals it forms from 40 to 50 per cent, of the portion of the earth's crust which is acce ible to observation. In combination, o. acts as a bivalent radicle. It unites directly with all the elements except fluorine, and also directly with some organic radicles, forming the cla of compounds called oxides and simple ethers. Combined with hydrogen, it unites with many elementary bodies and compound radicles to form (1) the oxyacids, comprising the great majority of all mineral and organic acids, and (2) the hydrates or hydroxides and alcohols. It is also a component of the derivatives of these two groups of compounds, called, respectively, (1) the oxysalts and compound ethers, and (2) the aldehydes and ketones. It further enters into combination with very many more complex organic radicles, forming an e ential constituent of nearly all of the animal and many of the vegetable organic compounds. The act of combination of o. with another body is called oxidation. It takes place continually in living ti ues, and is e ential to the maintenance of ti ue-metamorphosis. A free supply of o. is consequently nece ary for the preservation of animal life, and this supply is main tained by the proce es of respiration. O. is accordingly denominated a supporter of respiration. The proce of oxidation is always a ociated with the evolution of heat, and the development and maintenance of animal heat are secured by the constant oxidation taking place in the ti ues of the body. When oxidation takes place rapidly, the amount of heat suddenly developed is sufficient to cause a great elevation of temperature and the luminous phenomena constituting flame. The proce is then called combustion, and o. is said to be a supporter of combustion. It is used therapeutically as a gas, or by drinking water saturated with o. It is very useful as an inhalation in bronchitis and pneumonia where there is deficient aeration in consequence of heart-distention, in resuscitating persons asphyxiated by coal gas, in chloroform or ether narcosis, and to relieve dyspnoea in phthisis and diabetic coma. The saturated water is used for gastric or intestinal indigestion, nausea, and gastric or neuralgic headache. Atomic weight, 15-96; symbol, O. [B, 3; a, 34.] Active p. Ger., aktiver Sauerstoff. Nascent o.; an allotropic modification of o. containing only one atom in the molecule. It is formed by the action of a palladium plate saturated with hydrogen on ordinary p., and by the reduction or decomposition of ozone, hydrogen peroxide, and many other substances containing o. It cuii not be isolated. [E. Baumann, "Ztschr. f. phys. Chem.," v, p. 244 (B).] Heavy o. ether. A term erroneously applied to acetic aldehyde. [B, 46.] Light o. ether. An old term for acetic aldehyde (q. v.).O. acid. See under ACID. Polarized o. Ozone. [B.] Bespiratory o. The o., loosely combined with haemoglobin, which is available for respiration. [J.] too; Ua, blue; Us, lull; U, full; U, urn; U, like U (German). [s. 191]