The difference between the constitution of an inorganic salt (as above
described), and those of fats, is simply this: in the former there is only
one base with one acid, in the latter several fatty acids are united with
one base, whilst others also have several bases.
The most common fat base is the oxide of glyceril (with which we are
unacquainted in its pure state), but which we know unites with water
immediately after its separation from the other constituents of the
fats, and thus forms the glycerine, or sweet principle of oils.
In the salting operation, this glycerine sinks below the lye, and
becomes dissolved in the brine.
The most common fatty acids are: the margaric, the stearic, and the
oleic, which, uniting with the oxide of glyceril, form the margarine, the
stearine, and the oleine, of which, in various proportions, all fats
consist.
The margarine is found principally in the butters, and not drying
vegetable oils, the stearine in the suets, and the olein constitutes the
liquid portion of most animal and many vegetable fats; in these latter,
too, palmitin, another principle, and somewhat resembling margarine,
is sometimes traceable, especially in the palm oil.
The palm oil has also this additional peculiarity, that it contains free
acids, the quantity of which increases with its age, and hence the
reason why old palm oil saponifies better than fresh.
Pelouze and Boudet found in one sample of fresh palm oil, one-third
free acid, in another, one and a half, and in a third, nearly four-fifths of
its weight. There are, moreover, found in fats, tissues, albumen,
traces of slime, pigments, and often peculiar acids, which impart to
them a peculiar odor.
In regard to the mutton and goose fat, Chevreul has proved that they
owe their strong and penetrating odor to a peculiar substance which
he calls hircine.
Having thus made, as we think, some necessary remarks on the
immediate principle and nature of the fats, we proceed to a special
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