LARD AND LARD ADULTERATIONS. 515 



would indicate that the fat from which the cholesterin was obtained 

 was made up of equal proportions of animal and vegetable gl ycerides. 



SEPARATION OF STEARINE AND PALMITINE IN LARD. 



Isbert and Venator* have separated stearine and palmitine from lard 

 in the following manner : 



The sample is dissolved in cold ether in a test tube, and the closed 

 tube allowed to stand for some time. At the end of about two hours 

 the steariue begins to separate and is collected at the bottom of the 

 tube. The identity of the stearine was shown by its melting-point, viz, 

 GO . The palmitin separates later. 



The separation can also be effected by solution in boiling alcohol. 

 The separated glycerides are separated from olein by pressing between 

 blotting paper. 



ABSORPTION OF OXYGEN. 



Cotton oil absorbs a notable proportion of oxygen when subjected to 

 the Livache process.t 



Finely-divided lead is obtained by precipitating with zinc. About 1 

 gram of the lead powder is placed on a watch glass and mixed with 

 nearly 5 grams of oil. The disk is placed in a well-lighted room of 

 medium temperature. 



Cotton oil gains about G per cent, in weight in forty-eight hours. 

 The equivalent of oxygen absorption may also be approximately calcu- 

 lated for cotton oil from its iodine number by multiplying this by .063 

 (-^=.063). 



For cotton oil the number thus obtained is G.7 per cent. 



ELAIDINE REACTION. 



Oleic acid under the influence of nitrous acid is converted into an 

 isomeric elaidic acid. 



In like manner trioleiu C 3 H 5 (OCi8H 33 O)3 is converted into elaidine. 

 This substance is formed in crystalline masses, and its melting-point is 

 variously given at 32 to 38. Following is the method of applying the 

 elaidine test known as Pontet's process in the municipal laboratory of 

 Paris : 



Grams. 



Of the oil to be tested 10 



Nitric acid 5 



Mercury , 1 



Place in a test tube and shake vigorously for three minutes until the 

 mercury is dissolved ; allow to stand for twenty minutes, and shake 

 again for one minute. 



In from one to three hours the sample becomes hard. Olive, pea-nut, 

 and lard oils give the hardest elaidines. Copper may be used instead 



* Zeit. f. Angew. Chemie, June 1, 1888, p. 31G. 

 tMonitenr Scientifiqne, Vol. 1:5, p. 2'.'tt c t seq. 



