The use of low‐temperature crystallisation in the determination of component acids of liquid fats. II. Fats which contain linolenic as well as linoleic and oleic acids

The mixed fatty acids are first separated into sovorul groups by crystallisation from appropriate solvents at low temperatures. In each group the proportions of linolenic, linoleic, oleiu and saturated acids are determined spectrographically after isomerisation with alkali, 1 Palmitic acid and other saturated acids may be determined by fractional distillation of the completely hydrogenated methyl eaters of the total mixed fatty acids, or from direct ester‐fractionation of the methyl esters of each group of the mixed acids obtained by low temperature crystallization. The accuracy of the determination depends largely on the degree to which, by low temperature crystallisations, the mixed fatty acids are resolved into (i) portions rich in olcic and/or saturated acids (with only minor amounts of linoleic and linolenic acid) and (ii) portions rich in linoleic and/or linolenic acid (with relatively small proportions of oleic and saturated acids). The procedure is illustrated by determination of the component acids of linseed oil, of wheat germ oil, and of two specimens of rubber seed oil. The propects of rubber seed oil as a drying oil for the paint industry are briefly discussed.