414 
COFFEE. 
tract 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 
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 frequently 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 w r arm 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 theine , 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 somewhat of their aroma, in con¬ 
sequence of the influence of the oxygen of the air, which, owing to the porosity of the 
roasted berries, can easily penetrate. 
This pernicious change may best be avoided by strewing over the berries, when the 
roasting is completed, and while the vessel in which it has been done is still hot, some 
powdered white or brown sugar (half an ounce to one pound of coffee is sufficient). 
The sugar melts immediately, and by well shaking or turning the roaster quickly, it 
spreads over all the berries, and gives each one a fine glaze, impervious to the atmo¬ 
sphere. They have then a shining appearance, as though covered with a varnish, and 
they in consequence lose their smell entirely, which, however, returns in a high degree 
as soon as they are ground. 
After this operation, they are to be shaken out rapidly from the roaster and spread 
out on a cold plate of iron, so that they may cool as soon as possible. If the hot berries 
are allowed to remain heaped together, they begin to sweat, and when the quantity is 
large the heating process, by the influence of air, increases to such a degree that at last 
they take fire spontaneously. The roasted and glazed berries should be kept in a dry 
place, because the covering of sugar attracts moisture. 
If the raw berries are boiled in water, from 28 to 24 per cent, of soluble matter is ex¬ 
tracted. On being roasted till they assume a pale chestnut colour, they lose 15 to 16 
per cent., and the extract obtained from these by means of boiling water is 20 to 21 per 
cent, of the weight of the unroasted berries. The loss in weight of the extract is much 
larger when the roasting process is carried on till the colour of the berries is dark brown 
or black. At the same time that the berries lose in weight by roasting they gain 
in volume by swelling ; 100 volumes of green berries give, after roasting, a volume 
150 to 160; or two pint-measures of unroasted berries give three pints when roasted. 
The usual methods of preparing coffee are, 1st, by filtration; 2nd, by infusion; 3rd, 
boiling. 
Filtration gives often, but not always, a good cup of coffee. When the pouring the 
boiling water over the ground coffee is done slowly, the drops in passing come in contact 
with too much air, whose oxygen works a change in the aromatic particles and often 
destroys them entirely. The extraction, moreover, is incomplete. Instead of 20 to 21 
per cent., the w r ater dissolves only 11 to 15 per cent., and 7 to 10 per cent, is lost. 
Infusion is accomplished by making the water boil, and then putting in the ground 
coffee ; the vessel being immediately taken off the fire and allowed to stand quietly for 
about ten minutes. The coffee is ready for use when the powder swimming on the sur- 
