236 ANIMAL FATS AND PHOSPHATIDES. 



CH 3 

 Palmitic acid, (CH 2 )i4, crystallizes from an alcoholic solution in tufts 



COOH 



of fine needles. It melts at 61 C.; 1 still the admixture with stearic acid, 

 essentially changes them elting- and solidifying-points according to th 

 relative amounts of the two acids. Palmitic acid is somewhat more 

 soluble in cold alcohol than stearic acid; but they have about the same 

 solubility in boiling alcohol, ether, chloroform, and benzene. Its barium 

 salt contains 21.17 per cent barium, and silver salt contains 29.72 per 

 cent silver. 



CH 2 .O.Ci8H 33 O 

 I Olein, or triolein, C57Hio406, = CH.O.Ci8H 3 30, is present in all animal 



CH 2 .O.Ci 8 H 3 30 



fats, and in greater quantities in vegetable fats. It is a solvent for 

 stearin and palmitin. The oleic acid (elaic acid), CigH^Cb, as soaps, 

 probably has about the same occurrence as the other fatty acids. 



Olein is, at ordinary temperatures, a nearly colorless oil of a specific 

 gravity of 0.914, without odor or marked taste, and solidifies in crystalline 

 needles at -6 C. It becomes rancid quickly if exposed to the air. It 

 dissolves with difficulty in cold alcohol, but more easily in warm alcohol 

 or in ether. It is converted into its isomer, ELAIDIN, by nitrous acid. 

 CH 3 

 (CH 2 ) 7 



C*TT 



Oleic acid, /v^, is an unsaturated acid of the series CH n - 2 2 . and 

 U-ti 



(CH 2 ) 7 

 COOH 



correspondingly takes up two halogen atoms, i.e., iodine, at the double 

 bondage, a factor which is the basis of v. HUBL'S method for determining 

 the iodine equivalent. On taking up hydrogen, which can be accomplished 

 by heating with hydroiodic acid and amorphous phosphorus, it is trans- 

 fortned into the corresponding saturated acid, namely, stearic acid. On 

 oxidation the double bonds are satisfied by 2HO groups, and dioxystearic 

 acid, CH 3 (CH 2 )7CHOH.CHOH(CH2)7COOH, is formed. Oleic acid 

 readily undergoes oxidation in the air with the formation of acid products, 

 and the occurrence of monoxystearic acid, found in animal fats in certain 

 instances, can be explained by this oxidation. Oleic acid on heating 

 yields, besides volatile fatty acids, sebacic add, CioHigO^ which melts 

 at 127C; and with nitrous acid it is transformed into its isomer, solid 

 elaidic acid, which melts at 45 C. 



Oleic acid forms at ordinary temperature a colorless, tasteless, and 



1 Carlinfanti and Levi-Malvano, Chem. Centralbl. 1910. 





