222 RUBIACEA. 
slightly astringent, and bitterish taste. The commercial vari 
ties vary considerably in flavour, in size, and in the shade 
colour. On keeping, coffee loses during the first year about 
_ being at the same time greatly improved. 
In Mocha coffee the seed is often quite ovoid, only a single 
grain being contained in each fruit, . 
Chemical composition.—The sweetish pulp of the pericary 
contains several sugars, of which Boussingault (1881) found 
2°37 per cent. cane-sugar, 8°73 per cent. invert-sugar, and 2°21 
per cent, mannit. According to Payen’s analysis (1849), cof 
contains 13 per cent. of fat, 15°5 of glucose, dextrin, and 
undetermined vegetable acid, 10 of vegetable casein, 
chlorogenate of caffeine and potassium, 3 of nitrogenized prin 
ciple, 0°8 of caffeine, 0-00) of solid volatile oil, 0-002 of liq 
aromatic principle soluble in water, 6°7 of ash, and 1. of 
ture, the remainder being cellulose. The fat consis ts of pa 
and olein. The acids contained in coffee have been the s 
of repeated investigations. These render it probable 
besides a little citric acid, the principal one is caffeo-tannic 
which, according to Rochleder, is Payen’s chlorogenic acid 
precipitate with gelatin is soluble in the tannin solution 7 
emetic does not precipitate it, but it yields with lead salts 
o 
Se wh eae 
forms mostly yellow-coloured salts, and, like the a 
as ial oc rt Pee ; * my 
gum-like caffeo ny ‘using potassa pro’ 
