14 COMPOSITION OF THE OIL OF PRICKLY-PEAK SEED. 



were obtained, but no product that could be identified 

 with linusic acid (hexahydroxystearic acid). Examina- 

 tion of the oil for linolenic esters l>y the bromination pro- 

 cess yielded a negligible amount of hexabioiiiide. 



Accordingly the hquid fatty acids of prickly-pear 

 seed oil consist of a niixture of oleic and linoleic acids. 



The Solid Fatty Acids. 

 The solid fatty acids were obtained as a yellowish 

 cake (M.Pt. />()-;)3° ('.). The mean molecular weight was 

 determined as 250, hence it was assumed that the solid 

 acids consist almost entirely of palmitic acid. On purifica- 

 tion by crystallisation from alcohol fractions with melting 

 points from 58° to 61.5° C, were obtained. (M.Pt. of 

 palmitic acid : 62.6° C). A small fraction difficultly 

 soluble in alcohol, and separating in white flocks, was also 

 obtained. It melted from 78° C. to 82° C. was e\idently 

 a mixture, and probably consists mainly of lignoceric acid. 



Summary. 



1. The oil of prickly-pear seed is of the class of semi- 

 drying oils. 



2. Tt is composed of glycerides of oleic, linoleic. and 

 palmitic acids, with probably a small percentage of the 

 glyceride of lignoceric acid. 



