Page:The American Cyclopædia (1879) Volume III.djvu/552

546 CAFFEINE corps in Egypt, with the rank of brigadier gen- eral. Having, in the Syrian campaign, ini- tiated the siege operations at St. Jean d'Acre, he was shot in the left arm, April 9, 1799, and died from fever setting in after amputation. His writings on mathematics and philosophy, chiefly in periodicals, and his labors in behalf of education led to his admission to the French academy. CAFFEINE, the active principle in coffee, first extracted by Runge in 1820. It is a weak alkaloid, identical in chemical composition with theine, the active principle of tea. Being found in all the varieties of coffee as well as of tea, which are used as drinks by a large portion of the human race, it no doubt possesses some properties of importance to the animal system. Very few other substances contain so large a proportion of nitrogen as caffeine, its percent- age of this element amounting to 28'86. Its composition, as shown by Liebig, is represent- ed by the formula CeHioN^Oj, by which it appears to be closely related to some of the nitrogenized constituents of bile, as taurine, also to methyl-theobromine. It is obtained crystallized in long silky needles of a white color, which are fusible and volatile, and are easily dissolved in water, alcohol, and ether. To a decoction of coffee or tea acetate of lead is added to precipitate the caffeotannic acid. This is separated from the solution by filter- ing, and the excess of lead is removed by its precipitation by sulphuretted hydrogen. The liquor, again filtered, is then evaporated, and the caffeine crystallizes. It is purified by dis- solving and again crystallizing. The quantity obtained from coffee is generally about 1 per cent., which is only one half the amount fur- nished by tea; as the infusions are prepared, however, for ordinary use, more of the active principle is contained in a cup of coffee than in one of tea. Robiquet and Boutron give much larger proportions than 1 per cent. In Java coffee they found 4'4 per cent, of caffeine, and in Martinique coffee 6'4 per cent. Caffeine has a bitter taste, and acts powerfully upon the system when taken in doses of from 2 to 10 grains. It causes palpitation of the heart, great irregularity of the pulse, oppressions in the chest and pains in the head, confusion of the senses of hearing and seeing, sleeplessness, and delirium. The substance may be recogniz- ed by its great volatility, and the property it possesses, when dissolved in nitric acid, evapo- rated to dryness, and exposed to ammoniacal gas, of giving a pink-colored blush. Caffeine evaporated to dryness with a little chlorine water yields a purple-red residue, which be- comes golden yellow when more strongly heat- ed, but red again on addition of ammonia ; by this reaction it may be detected even in a single coffee bean. Caffeine has been formed syn- thetically by treating the silver compound of theobromine with methyl-iodide. On a large scale caffeine can be prepared from tea by heating the concentrated aqueous decoction CAFFRARIA with litharge, evaporating the decanted liquid to a sirup, and treating it with pearlash and alcohol. Claus finds that the interior com- mercial sorts of tea are richer in caffeine than the finer and more fragrant varieties. Caffeine is sometimes used in medicine to produce sleep, allay nervous irritability, and relieve sick head- ache. It should only be used for these pur- poses in cases of debility. Inflammation con- traindicates its use. The dose is one or two grains repeated every hour till eight or ten grains are taken if necessary. CAFFI, Ippolito, an Italian painter, born in Belluno in 1814. He studied in Venice and Rome, visited the East, and in 1848 barely escaped being shot by the Austrian authorities on account of his participation in revolutionary outbreaks. After the capitulation of Venice he took up his residence in Piedmont. He ex- cels in monumental views by an original dispo- sition of light and shade. His most celebrated picture is "The Carnival in Rome," which was exhibited at the Paris exposition of 1855, and which he has reproduced more than 40 times. CAFFRARIA, or Kaffraria. I. Also called Ka- li r.laiul, a country in the E. part of South Africa, between Cape Colony and Natal, extending N. on the coast from the Great Kei river to the Umzimculu, about 140 m., and inland about 90 m. to the Storm and Qnathlamba moun- tains, between lat. 30 and 32 40' 8., and Ion. 27 30' and 30 E. ; area, about 16,000 sq. m. ; pop. about 135,000. Before the British en- croachments Caffraria extended 600 m. along the coast from the Great Kei river to Delagoa bay, and included what is now Natal and Zoo- Zooloo Youths in Dancing Costume. loo Land. The climate is warm, but healthy ; the lower parts of the hillsides are cultiva- ted principally with maize, millet, and water-