THE PREPARATION OF COFFEE. 163 
‘‘The chief operation is the roasting. On this de- 
pends 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 it is done in the Hast, 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 consequence of the in- 
fluence 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 strew- 
ing 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 atmosphere. They have then a shining ap- 
pearance, as though covered with a varnish, and they 
im consequence lose their smell entirely, which, how- 
ever, 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 on a cold 
plate of iron, so that they may cool as soon as pos- - 
sible. 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. 
‘‘Tf the raw berries are boiled in water, from 23 
to 24 per cent of soluble matter is extacted. On 
being roasted till they assume a pale chestnut colour, 
they lose from 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 
