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ALKALI SOILS. mate," United States Department of Agriculture, Weather Bureau Bulletin 3 (Washington, 1892); "Origin, Value and Reclamation of Alkali Lands," United States Department of Agriculture Year-book, 1895 (Washington, 1896); "Nature, Value, and Utilization of Alkali Lands," California Experiment Station, Bulletin 128 (Sacramento, 1900); United States Department of Agriculture, Bureau of Soils, Bulletins 14, 17, 18, and Reports of Field Operations for 1899, 1900 (Washington, 1900-01); Reports of Wyoming Experiment Station (Laramie, 1896-1900); T. H. Means, "The Soluble Mineral Matter of Soils," United States Department of Agriculture Year-book, 1898 (Washington, 1899): J. G. Smith, "Forage Plants for Cultivation on Alkali Soils." United States Department of Agriculture Year-book, 1898 (Washington, 1899); G. P. Merrill, A Treatise on Rocks, Rock Weathering and Soils (New York, 1897).

AL'KALOIDS (Literally, resembling alkali). A term applied to all nitrogenous basic compounds found in plants. The alkaloids are as a rule the most important medicinal principles of the plants from which they are derived, and in moderate doses constitute therapeutic agents of the highest value. In larger quantities, however, they are extremely poisonous. Most alkaloids are chemically composed of carbon, hydrogen, nitrogen, and oxygen. A very few, including the well-known nicotine of tobacco, and coniine, contain carbon, hydrogen, and nitrogen, but no oxygen. The alkaloids that contain oxygen are non-volatile solids, and can mostly be obtained in the form of colorless crystals. Those that contain no oxygen are volatile liquids. The separation of the two groups of alkaloids can therefore be readily effected by simply subjecting the given mixture to a process of distillation.

Many alkaloids are chemically related to the organic bases called pyridine and quinoline (qq.v.). Thus coniine, nicotine, piperine, atropine, cocaine, and others have been shown to be derivatives of pyridine: quinine, cinchonine, strychnine, brucine, etc., have been shown to be derivatives of quinoline. Other alkaloids, including caffeine, or theine, and theobromine, are related to uric acid. In contradistinction to these true, or natural alkaloids, a certain number of substances not found ready-formed in nature, but prepared artificially in the chemical laboratory, have been termed artificial alkaloids. Antipyrine, kairine, thalline, and the ordinary acet-anilide, or antifebrine, are examples of artificial alkaloids, which resemble the natural alkaloids both in their chemical constitution and physiological action. Of the natural alkaloids but very few have as yet been reproduced artificially. Another few, including atropine and cocaine, have been reconstructed from their decomposition products.

The separation and detection of the several alkaloids is often a matter of great importance in medico-legal examinations. The analytical method usually employed (the so-called Stas-Otto method) consists in partially separating the given mixture by the use of water, alcohol, ether, chloroform, benzine, and amyl alcohol, then applying tests depending upon the characteristic reactions of the various constituents. Tannic, picric, and phospho-molybdic acids, potassium-mercuric iodide, and a few other reagents form insoluble precipitates with the alkaloids.

The following are the more important natural alkaloids, their characteristic properties, and the sources from which they are obtained:

Aeonitinc, C33H43NO,,; melting point, 184° C; insoluble in water; soluble in alcohol, ether, and chloroform : a violet coloration is produced when its solution in phosphoric acid is cautiously evaiMirated. It is found in aconite, the tuber of Aconitum nnpellus Linné.

Atropine, or Daturine, Ci,Hj,NO, ; melting point, 115° C.; soluble in alcohol and chloro- form; sparingly soluble in hot water and in ether. It does not exist ready-formed in nature, but is produced by the transformation of the alkaloid hyoscyamine.

Berberine, C,„H„NO,+4..5H.O; melting point, 120° C.; soluble in hot water or alcohol; its aqueous solution is colored red by chlorine. It is found in yellow puccoon, the rhizome and roots of Hydrastis canadensis Linné; also, in Canadian moonseed, the rhizome and roots of Menispermum canadense Linné, and in other plants.

Brucine, C.,HmN.04+4H,0 ; melting point, 100° C; soluble in alcohol and in chlorofi-om. It imparts to strong nitric acid a red coloration that gradually changes to yellow; the coloration becomes violet on addition of stannous chloride. It is found, along with strychnine, in nux vomica.

Caffeine, or Theine, CsHi„N40,; melting point, 2,30.5° C.; soluble in hot water and in chloro- form; sparingly soluble in hot alcohol. If its solution in chlorine water is evaporated and am- monia added to the residue, the latter turns pur- ple. It is found in many plants and is con- tained in considerable quantities in tea and. coffee.

Cinchonidine, CisHi^NjO: melting point, 200.5° C. ; soluble in chloroform and in alcohol. It is laevo-rotatory (i.e., its solutions turn the plane of polarized light to the left). It is found along with quinine in cinchona bark.

Cinchonine, C,9H~.N;0 (hence, isomeric with cinchonidine); melting point, about 240° C. ; sparingly soluble in chloroform and in hot alco- hol. It is dextro-rotatory and is found in cin- chona bark.

Cocaine, CtH^'NO, ; melting point, 98° C; soluble in alcohol and in ether; sparingly soluble in water. It produces local anaesthesia when in- jected subcutaneously or applied to mucous membranes. It is found in coca, or cuca, the leaves of Erythroxylon coca Lamarck.

Codeine, C|,H^N0;;: melting point, 155° C; soluble in alcohol, chloroform and ether. With strong sulphuric acid and chloride of iron it gives a blue coloration. It is one of the alka- loids contained in opium.

Colchicine, C,;H.,NO„: melting point, 145° C; soluble in water, alcohol and chloroform. It im- parts to strong nitric acid a violet color which gradually turns brown. It is the active prin- ciple of colchicum root, the corm of Colchicum autumnale Linné.

Coniine, C,H,;N; boiling point, 108.5° C; soluble in alcohol, ether, and chloroform; sparingly soluble in water. Its aqueous solution gives a brown precipitate with a solution of iodine. Coniine has dextro-rotatory power. It is the active principle of hemlock, the fruit of Conium maculatum Linné.

Curarine. CisH^^N (or C,„H,jN ?); a yellow powder, soluble in water and in alcohol; turns purple if treated with strong hydrochloric acid. It is the active principle of the South American