101
I. REGNUM INORGANICUM .—THE INORGANIC KINGDOM.
Okder I.— Oxygen and its aqueous solution.
Oxyge'nium. — Ox'ygen.
History, synonymes, and etymology. —Oxygen gas was discoveredon the 1st of August, 1774, by Dr. Priestley, who denominated it dephlogis-ticated air. In the following year, Scheele also discovered it, withoutknowing what Priestley had done, and he called it empyr'eal air. Con-dorcet termed it vital air. Lavoisier called it oxygen , from (oZvc, acid;and yevvaw, to engender or produce.)
Natural history. — (a.) In the inorganized kingdom,. —Oxygen is, ofall substances, that which is found in the largest quantity in nature,for it constitutes at least \ of the known terraqueous globe. Thus, water,which covers about three-fourths of the surface of the earth, contains| of its weight of oxygen; and the solid crust of our globe probablyconsists of at least f part, by weight, of this principle ; for silica, car-bonate of lime, and alumina, the three most abimdant constituents of theearth’s strata, contain nearly half their weight of oxygen. Mr. De laBeclie ( Researches in Theoretical Geology, p. 8) calculates that silicaalone constitutes “ forty-five per cent, of the mineral crust of our globe.”Of the atmosphere, oxygen constitutes 20 or 21 per cent, by volume,or about 23 per cent, by weight, to which must be added 8, by weight, ofthe atmospheric aqueous vapour.
{b.) In the organized kingdom. —Oxygen is an essential constituent ofall living bodies. Vegetables, in the sun’s rays, absorb carbonic aciddecompose it, retain the carbon, and emit the oxygen Hence they havebeen supposed to be the purifiers of the atmosphere.
Preparation. —There are several methods of procuring this gas, butI shall notice three only:—
1. By heating chlorate of potash in a glass retort. —This methodyields pure oxygen gas. One equivalent, or 124 parts of chlorate ofpotash, yield six equivalents or 48 parts of oxygen, and one equivalentor 76 parts of chloride of potassium.
SUBSTANCES USED.
1 eq. Chlorate Pot h . 124
leq. Chlo c . Acid 76 ^1 eq. Potash . . 48 ^
5 eq. Oxy. 401 eq. Chlo. 361 eq. Oxy. 81 eq. Pot ra .40
1 eq. Chloride Potas m . 76
2. By heatingbinoxide of manganesein an iron bottle. —This is the cheap-est method, and, for ordinary purposes, it yields oxygen gas sufficientlypure. To free the gas from carbonic acid, wash it with lime-water orwith a solution of caustic potash. One pound of the commercial binoxideusually yields from 30 to 40 pints of gas : but, from fine samples, 40to 50 pints may be procured. Two equivalents or 88 parts of purebinoxide yield one equivalent or 8 parts of oxygen, and two equivalentsor 80 parts of the sesquioxide of manganese.
SUBSTANCE USED. RESULTS.
2 eq. Binoxide Manganese 88 \ ^ giq^ortde Manganese 80