Physics and Chemistry. 107 
Coffee roasted only until it becomes slightly red, preserves the maxi- 
mum of weight and of aroma, but gives out less coloring matter. In 
this state, 100 parts are found to have lost 15, while vols. have in- 
creased to 130. Roasted to a chesnut color, as is commonly done, the 
loss is 20 per cent., while the increase in volume is from 100 to 153. 
This swelling of the grain depends upon the property which the nitro- 
genous matter deposited within the tissue has, of puffing up remarka- 
bly when heated. 
If the heat is continued until a dark brown color is produced and the 
grain becomes covered with a sort of glaze, the loss is 25 per cent., 
while the original quantity of nitrogen, 2°45 per cent., is reduced to 
1-77, being a loss of one fourth. 
The loss of soluble matter was found to be proportionate to the loss 
in weight, but in order to obtain results of practical value, instead of 
exhausting the coffee, the usual domestic process was tried. One litre 
of water (nearly 1 qt.) was filtered through 100 grammes (1500 grains) 
of each kind, and there was obtained of soluble matter from the brown 
cotlee 16:15; from the chestnut, 19-00, and from the red, 25:00. 
The difference in the aroma being nearly the same, the lower degree 
of roasting will produce not only the best and most nutritious beverage, 
but one free from the harsh and bitier flavor caused by action of too 
high heat upon the nitrogenous matter. 
The nature of the substances dissolved, renders this beverage not 
only agreeable but nutritious, compared with tea (the coffee being 100 
. to one litre of water, the tea 20 gram. to one litre); the former 
contains three times the quantity of solid matter and double the nitrogen, 
of the latter. With an equal bulk of milk, and the usual amount of 
sugar, this drink contains six times the solid, and three times the nitro- 
genous matter that broth does. ; By 
The partial substitution of succory for coffee, was proved to be with- 
out real advantage, as the latter substance contains a much smaller 
amount of nutriment and little or no aroma, but more coloring matter. 
ew double salt and acid of coffee. Direct extraction of caffeine.— 
The new compound discovered by Payen, appears to have escaped no- 
tice, by reason of its remarkable disposition to change. In fact this 
has- 
tening this action, a very delicate test was obtained for the new sub- 
stance, and at last after much trouble, the means for its separation were 
tedbss S53 ate, — 
The process adopted affords caffeine as well as the new gerne 
Coffee is reduced to powder, exhausted with ether, pe eaieya SYApo- 
rated to dryness, and the fatty residue well wasbed with boiling water. 
The washings evaporated, leave a yellowish brown substance, which, 
treated with absolute alcohol, gives om evaporation, Crys oer 
feine—the usual washing with cold, and erystallization a tos ampamaai 
furnish it perfectly pure. i 
Having obtained the equivalent of this substance, Payen was able to 
control the analysis, which is different from that hitherto received. His 
formula is C,, H,. N, Og. 
