14 
POPULAE SCIENCE EEVIEW. 
milk and assisted by a cigar, as a very acceptable means of 
assisting certain organic processes. 
For tbe same reason, so it is said, Russian ladies have 
become patronesses of coffee and tobacco. 
These remarks prove sufficiently that the preparation of a 
beverage possessing in the highest degree the above valuable 
qualities, cannot be without interest. 
I was originally led to my attempts in this matter by the 
intention to obtain an extract of coffee, which might be useful 
for travellers and for armies on a march ; and on this occasion 
I became aware of the influence which the atmosphere, or 
the oxygen in the atmosphere, exercises on coffee, by which 
its qualities are very materially deteriorated. I have found 
that a watery hot extract of roasted coffee, which, when fresh, 
is perfectly enjoyable — if allowed to evaporate, quickly or 
slowly, in a high or low temperature, loses by degrees its 
agreeable flavour from coming in contact with the air; a 
black mass remains that cannot be entirely redissolved in cold 
water, and which on account of its bad taste cannot be used. 
Be the method of preparing coffee what it may, it is first 
requisite to sort the berries. Foreign substances are fre- 
quently, found among them, bits of wood, feathers, and usually 
a number of black mouldy berries, which must be taken 
away; for our sense of taste is so delicate that the smallest 
admixture cannot escape notice. 
Berries of dark or green hue are generally dyed ; and these 
must first be washed in a little water and afterwards dried 
with a warm linen cloth ; with those of a pale colour this is 
unnecessary. 
The next operation is the roasting. On this depends the 
good quality of the coffee. In reality the berries should only 
be roasted until they have lost their horny condition, so that 
they may be ground, or, as is done in the East, pounded to 
a fine powder. 
Coffee contains a crystalline substance, named caffeine or 
theme , because it is also a component part of tea. 
This matter is volatile, and every care must be taken to 
retain it in the coffee. For this purpose the berries should 
be roasted till they are of a pale-brown colour ; in those 
which are too dark there is no caffeine ; if they are black the 
essential parts of the berries are entirely destroyed, and the 
beverage prepared from these does not deserve the name of 
coffee. 
The berries of coffee, once roasted, lose every hour some- 
what of their aroma, in consequence of the influence of the 
oxygen of the air, which, owing to the porosity of the roasted 
berries, can easily penetrate. 
