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CHAPTER X
SAPONIFIABLE OILS, FATS AND WAXES

Composition. — The chief constituents of animal and vegetable
oils are esters derived from fatty acids and glyccrol, a triatomic
alcohol. Of the former the most important are palmitic, stcaric
and oleic acids, the first two being saturated, the last an un-
saturated acid. The glycerides of these acids are respectively
known as palmitin, stearin and olein and they have the following
composition:

CaHB(Cl6H8i02)8,

Palmitin

Stearin

In addition to these are esters of higher alcohols other than
glycerine and of other saturated and unsatunited fatty acids,
also in certain cases small amounts of free higher alcohols. The
chief differences in properties of different oils arc* caused by varia-
tions in the proportions of the constituent esters. Vegetable
oils contain much palmitin while stearin predominates in animal
oils. The more liquid oils contain more olein and eaters of acids
having smaller molecular weights.
The animal and vegetable oils and fats are thus in a class quite
distinct from that of mineral oils, the latter being mixtures of
various saturated and unsaturatocl hydrocarbons, not Hapomfi-
able, as distinguished from the saponifiable esters of the former
class.
Waxes.— The true waxes differ chemically from the oils and
fate in that they are not glycerides but arc* esters of mono- or
diatomic, alcohols with the higher fatty acids. Those alcohols
are either aliphatic; or aromatic. Following are some examples
of such esters: Oetyl palmitate, derived from palmitic acid and
cetyl alcohol, Oi«H3j»OH; thin is the chief constituent of sperma-
ceti. Oeryl palmitate, the chief constituent of opium wax, IB
derived from palmitic acid and eeryl alcohol, C«?HpOH. Myri-
170 *