74 ORGANIC CONSTITUENTS. 



The formula for margarin is C^g H^^ 0^,,, corresponding with 



H O J 



1 Atom glycerin . . . Cg H, O5 



2 Atoms margaric acid . . C70 Hg, Og J.= C.g R-,- 0,2 

 1 Atom water . . . 



6. Oleic acid. This acid is obtained from the olcate of 

 potash, which is produced during the preparation of the stearate 

 and margarate of potash, and remains in solution. It must 

 be separated by the addition of a mineral acid, and then well 

 washed and shaken in hot water. It is an oily fluid, of a clear 

 yellow colour, and does not assume a solid form until it is 

 cooled several degrees below the freezing point of water. At 

 about 19° or 20' it congeals into Avhite acicular crystals. It 

 is very acid, and has a rancid odour and taste. Its specific 

 gravity is 0-898. It is not soluble in water, but dissolves in 

 alcohol in all proportions, and the spii'ituous solution acts freely 

 on litmus paper. It combines with stearic and margaric acids 

 in all proportions, and the perfect separation of the acids in 

 such cases is not very easy. Its composition, according to 

 Varrentrap, is represented by the formula C^^ H^^ O^ + HO. 



Oleic acid may be distilled in vacuo without undergoing any 

 change ; but if atmospheric air be admitted, a small portion 

 only passes over tmaltered, while the greater part is decom- 

 posed, and some carbon remains in the retort. 



fl At. sebacic acid C,(, Hg O4 



3 At. carbonic acid C3 Og 



2 Atoms bydrated oleic acid, Cgg H^u 0„„ produce <^ Hydi-ocarburet C, H-, 



>- Residual carbon C^ 



Sebacic acid was formerly considered as a product of the 

 destructive distillation of all fatty bodies, but it has been shown 

 by Redtenbacher to arise only from oleic acid. Oleic acid 

 removes carbonic acid from bases. The oleates do not crys- 

 tallize; those which are soluble appear as soft, easily fusible 

 bodies, and are more soluble in alcohol than in water. The 

 oleates of potash and soda, if treated Avith a sufficient quantity 

 of water, become reduced to binoleates, and a portion of the 

 base is freed. The oleate, as well as the stearate of soda, 

 exists in the bile. The blnoleate of glycerin, usually termed 

 olein, exists in small quantity in the various soHd fats, but 

 forms the principal mass of the liquid fixed oils. It exists as an 

 oleaginous fluid, and varies in some respects, especially in regard 



