racted, the volatile aromatic and
flavoring constituents of the coffee are removed also. These substances,
which are essential for the maintenance of quality by the coffee, though
readily separated from the caffein, can not be returned to the roasted
bean with any degree of certainty. This virtually insurmountable
obstacle forced the abandonment of this mode of attack.

In order to avoid this action, the attention of investigators was
directed to extraction of the alkaloid in question from the green bean.
Because of the difficulty of causing the solvent to penetrate the bean,
recourse to grinding resulted. This greatly facilitated the desired
extraction, but a difficulty was encountered when the subsequent
roasting was attempted. The irregular and broken character of the ground
green beans resisted all attempts to produce practically a uniformly
roasted, highly aromatic product from the ground material.

Avoidance of this lack of uniformity in the product, and the great
desirability to duplicate the normal bean as far as possible,
necessitated the development of a method of extraction of the caffein
from the whole raw bean without a permanent alteration of the shape
thereof. The close structure of the green bean, and its consequent
resistance to penetration by solvents, and the existence of the caffein
in the bean as an acid salt, which is not easily soluble, offered
resistance to successful extraction.

As a means of overcoming the difficulty of structure, the beans were
allowed to stand in water in order to swell, or the cells were expanded
by treatment with steam, or the beans were subjected to the action of
some "cellulose-softening acids," such as acetic acid or sulphur dioxid.
As a method of facilitating the mechanical side of extraction without
deleterious effects, the treatment of the coffee with steam under
pressure, as utilized in the patented process of Myer, Roselius, and
Wimmer,[141] is probably the safest.

Many ingenious methods have been devised for the ready removal of the
caffein from this point on. Several processes employ an alkali, such as
ammonium hydroxid, to free the caffein from the acid; or an acid, such
as acetic, hydrochloric, or sulphurous, is used to form a more soluble
salt of caffein. Other procedures effect the dissociation of the
caffein-acid salt by dampening or immersion in a liquid and subjecting
the mass to the action of an electric current.

The caffein is usually extracted fr