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PHAHMACOLOGIA SPECIALIS-SPECIALPHARMACOLOGY.

Special Pharmacology treats of medicines individually. These I shall, forthe most part, arrange in Natural-Historical Order.

Natural bodies are divided into two groups, called Kingdoms; the Inorganizedand the Organized. The latter is subdivided into two Sub-Kingdoms, the Ve-getable and the Jinimal.

Formerly naturalists admitled three kingdoms; the Mineral, the Vegetable, and the Ani-mal. But the impossibility of so characterizing the lattcr two as to distinguish them froinone another, has led later writcrs to uoite thcrn into one kingdorn.

Brogniart {Tahlcau de la Distribution Methodique des Especes Minorates. Paris, 1833.)makes thrce divisions of bodies,—the Jnorganic, the Organic, and the Organized.

I. INORGANIZED KINGDOM.GElass X. äJltm=JWetaUtc Suöstiwccs.

(Metalloids,— Berzelius.)

Order I. OXYGEN, AND ITS AQUEOUS SOLUTION.OXYGEN'IUM.—OXYGEN.

History, Synonymes, and Etymology. —Oxygen gas was discovered, on theIst of August, 1774, by Dr. Priestley, {Experiments and Observations on diffe-rent kinds of Mir, vol. ii. p. 106. Birmingham, 1790.) who denominated it de-phlogisticated air. In the following year, Scheele also discovered it, withoutknowing what Priestley had done, and he called it empyreal air. Oondorcetterraed it vital air. Lavoisier called it oxygen, (from o|t>s-, acid; and yevtxa, Iengender or produce.)

Natural History. —Oxygen is found in both kingdoms of nature.

a. In the inorganized kingdom. —Oxygen is, of all substances, that which is found in thelargest qnantity in nature, for it constitutes at least three-fourths of the known terraqueousglobe. Thus, water, whieh Covers about thrce-fourths of the surface of the earth, containseight.ninths of its weight of oxygen; and the solid erust of our globe probably eonsists of atleast one-third part, by weight, of this principle; for silica, carbonate of lime, and alamina,the three most abundant constituents of the earth's strata, contain nearly half their weight ofoxygen. Mr. De la Reche (Researches in Theoretical Geology, p. 8. Lond. 1834.) ealculatesthat silica alone constitutes " forty five per Cent, of the mineral crust of our globe." Of theatmosphere, oxygen constitutes twenty or twenty-one per cent. by Volume, or about twenty-three per cent. by weight, to which must be added eight ninths, by weight, of the atmosphericaqueous vapour.

In the organized kingdom.— Oxygen is an essential constituentof all living bodies. Vege-tables, in the sun's rays, absorb carbonic acid, decompose it, retarn the carbon, and einil theoxygen. Hence they have been supposed to bc the puriners of the atmosphere.