[Illustration--Drawing: PURE DECORTICATED COCOA, HIGHLY MAGNIFIED.]

Such adulteration is rendered possible by the presence in the bean of
a large proportion of fatty matter or cocoa-butter, which renders it
too rich for most digestions. To overcome this difficulty one or other
of two methods is available: (1) Lowering the percentage of fat by the
addition of starch, sugar, etc.; or (2) removing a large proportion of
the fat by some extractive process; this latter method being in every
respect preferable to that first mentioned.

[Illustration--Drawing: COCOA ADULTERATED WITH ARROWROOT OR POTATO STARCH.]

In order to avoid the expense and trouble consequent on the latter
process, some manufacturers add alkali, by which means the free fatty
acids are saponified, and the fat is held in a state of emulsion, thus
giving the cocoa a false appearance of solubility.

Another effect of the alkali is to impart to the beverage a much
darker colour, from its action on the natural red colouring matter of
the cocoa, this darkening being often taken, unfortunately, as
indicative of increased strength. On this account the presence of
added alkali should be regarded as an adulteration, unless notified on
the package in which the cocoa is contained.

A more subtle treatment with alkali for the same purpose is the
addition to the pulverized bean of carbonate of ammonia, or caustic
ammonia. This is afterwards volatilized by the application of heat.
Scents and flavourings are then added to disguise their smell and
taste.