A guide to the alterations in the British pharmacopoeia, 1885 : comprising an epitome of the changes, and an account of the new preparations, their characters, uses, doses, and modes of administration; together with a therapeutical commentary / by Prosser James.

James, Prosser, 1836-1918

Date:: 1889

Credit: A guide to the alterations in the British pharmacopoeia, 1885 : comprising an epitome of the changes, and an account of the new preparations, their characters, uses, doses, and modes of administration; together with a therapeutical commentary / by Prosser James. Source: Wellcome Collection.

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$NEW ACTIVE PRINCIPLES AND PLANTS. CAFFEINA,—CAFFEINE.—CgHioNA.H.O. Synonyms.—Caffeia ; Theina ; Guaranina. An alkaloid usually obtained from the dried leaves of Camellia Thea, Link,, or the dried seeds of Coffea arabica. Linn., by evaporating aqueous infusions from which astringent and colouring matters have been removed. Characters ajtd Tests.—Colourless, silky, inodorous, acicular crystals. Soluble in 80 parts of cold water, the solution having a faintly bitter taste and being neutral to litmus. j\Iore soluble in boiling water and in rectified spirit, and very soluble in chloroform ; sparingly soluble in ether. At 212° F. (100° C.) the crystals lose 8*49 per cent, of their weight, and at a higher temperature melt and volatilise without decomposition. Treated with a crystal of chlorate of potassium and a few drops of hydrochloric acid, and the mixture evaporated to dryness in a porcelain dish, a reddish residue results, which becomes purple when moistened with ammonia. In an aqueous solution of the alkaloid, tannic acid gives a white precipitate soluble in excess of the reagent. Preparation.—Caffeinas Citras. Caffeine is here assumed to be identical with theine, theobromine, and guaranine, but I have observed differences in the alkaloids from these sources, which may prove of some importance. Caffeine is rather insoluble, and possesses only very feeble basic qualities—hence the formation of salts is not easy. Double salts with sodium enable us to obtain solutions adapted for hypodermic injection. Caffein 20 grains and salicylate of sodium 17^ grains may be dissolved in I drachm of distilled water for extemporaneous use, 3 minims containing i grain of the alkaloid—but it is better to use a more definite salt. [The author has obtained from certain preparations a degree of local anaesthesia, experimenting with a view of comparing them with salts of cocaine. {Lancet, 1885)]. Some of the properties of coffee doubtless depend on the empyreumatic oil, but both coffee and caffeine are stomachic and stimulant in moderate doses. The alkaloid is also said$