MARGARIC ACID. 107 



Carbon 34 atoms 



Hydrogen .... 33 



Oxygen 3 



Water 1 



1 OO'OOO 



The atomic weight of the hypothetical anhydrous acid =3262*5, 

 and its saturating capacity =3*065. 



Combinations. Margaric acid forms both neutral and acid 

 compounds with alkalies ; the acid salts are principally formed by 

 the addition of much water to the neutral salts ; with oxide of lead 

 it forms acid, neutral, and basic salts, all of which are soluble in 

 petroleum and oil of turpentine, and the first two in heated alcohol. 



Margaramide, H 2 N.C 34 H 33 O 2 , is formed when olive oil is 

 digested in alcohol saturated with ammonia ; it crystallises in fine, 

 silky, glistening needles, is insoluble in water, and is more soluble 

 in hot alcohol and ether than in cold, from which it separates in 

 glistening plates ; it fuses at 60, and when ignited, burns like 

 tallow, 



On treating margaric acid with peroxide of lead, Bromeis* 

 obtained a fatty acid which separated in granules and contained 

 1 atom more of oxygen than margaric acid ; its composition being 

 represented by the formula C 34 H 33 O 4 .HO. 



Preparation. Since margaric acid, in the compound which we 

 call margarin, occurs in almost all vegetable fats (the fatty oils) as 

 well as in the most common animal fats, it may be prepared from 

 any of these sources. The best method of obtaining it is to take 

 the fat of man or of the pig, or a vegetable fat, and to saponify it 

 with potash so as to form a clear, viscid, soapy solution ; this must 

 be treated with sulphuric acid, which causes a separation of a mix- 

 ture of stearic, margaric, and oleic acids ; this fatty mass must be 

 then well washed with water, dried as thoroughly as possible, and 

 strongly pressed between paper, which causes the removal of a 

 great part of the oleic acid. The solid acids must now be recrys- 

 tallised in alcohol. The stearic acid is the first to separate from 

 the hot alcoholic solution, and it thus admits of separation and 

 removal ; the margaric acid always separates somewhat later ; in 

 order, however, that the stearic acid may be perfectly removed, 

 this process must be several times repeated. 



We thus obtain margaric acid with no impurity beyond a little 

 oleic acid, which may be removed by saturating the acids with an 

 alkali and precipitating with acetate of lead ; as the oleate of lead 

 * Anu. d. Ch. u. Pharm. Bd. 42, 8. 56. 



