THE ALKALOID OF COCOA. 937 
the fat skimmed off, and the residue pressed out. The beans are now roasted, 
husked, and very finely ground. The mass is heated to 70°-80° C., packed in sacks 
of ticking, and submitted to pressure between previously warmed or steam-heated 
plates. The fat expressed, about 30-35 per cent, is filtered through dry filters. The 
pure residue, containing 10-15 per cent of oil, is made into chocolate. For the prep- 
aration of an entirely fat-free cocoa powder, the roasted and ground beans are ex- 
hausted with benzine or ether. 
Theobromine, the alkaloid of cocoa, is very closely related chemically 
(it is dimethyl xanthine, C;H.(CH3).N,O., while caffeine is trimethyl 
xanthine, C;H(CH;);N,O,) to caffeine, the alkaloid of tea and coffee, 
and has similar effects on the system; the power possessed by the bev- 
erages prepared from these substances, ‘+ to cheer and not to inebriate,” 
being largely due to the presence of these alkaloids. 
Separated from the bean, it is a white powder, permanent in the air, 
crystallizable in microscopic rhombic needles, and having a very bitter 
taste. While neutral in reaction, it acts as a weak base, uniting with 
acids to form crystallizable salts, which become basic on treatment with 
water; its salts of volatile acids give up their acids on heating, at or 
below 100° C. According to Blyth,! it begins to sublime at 134° C.,, 
and yields distinct crystals at 170° C. and above; Keller, 1854’, reports 
the subliming point as 290°-295° C.; other writers note it as about 290° 
C. Treumann’® has reported its solubility in water to be 1 in 148.5 at 
100° C., and 1 in 1,600 at 17° C.; in absolute alcohol, 1 in 422.5 at the 
boiling point, and 1 in 4,284 at 17° C.; in boiling chloroform, 1 in 105. 
Husemann‘ states its solubility in water to be 1 in 55 at 100° C., 1 in 
660 at 20° C., and 1 in 1,600 at 0° C.; in cold alcohol, 1 in 1,460, and in 
boiling alcohol, 1 in 47; in cold ether, 1 in 17,000, and in boiling ether, 
1 in 600; more soluble in chloroform and warm amyl alcohol than in 
water, less soluble in benzol, and insoluble in petroleum ether. 
! Op. cit., note 3, p. 956 of this work. 
2 Op. cit., note 3, p. 938 of this work. 
3 Archiv. d. Pharm., [3] 13,5; Jahresb. d. Chem., 1878, 872. 
*Husemann’s Pflanzenstoffe. 
