THE VOLATILE PAET OF PLANTS. 91 



However greatly the various fats may differ in external 

 characters, they are all mixtures of a few elementary fats. 

 The most abundant and commonly occurring fats, espe- 

 cially those which are ingredients of the food of man and 

 domestic animals, viz. : tallow, olive oil, and butter, con- 

 sist essentially of three substances, which we may briefly 

 notice. These elementary fats are Stearin, Palmitin, and 

 Olein^ aiid they consist of carbon, oxygen, and hydrogen, 

 the first-named element being greatly preponderant. 



Stearin is represented by the formula C„ H^j, 0^. It 

 is the most abundant ingredient of the common fats, and 

 exists in largest proportion in the harder kinds of tallow. 



Exp. 40. — Heat mutton or beef tallow, in a bottle tliat may be tightly 

 corked, with ten times its bnllc of concentrated ether, until a clear solu- 

 tion is obtained. Let cool slowly, when stearin will crystallize out in 

 pearly scales. 



Palmitin, C^,, H^j 0„ receives its name from the palm 

 oil, of Africa, in which it is a large ingredient. It 

 forms a good part of butter, and is one of the chief con- 

 stituents of bees-wax, and of bayberry tallow. 



Olcin, Cj, H,„ Oj, is the liquid ingredient of fats, and 

 occurs most abundantly in the oils. It is prepared from 

 olive oil by cooling down to the freezing point, when the 

 stearin and palmitin solidify, leaving the olein still in the 

 hquid state. 



Other elementary fats, Tiz. : butyrin, laurin, myristin, etc., occur in 

 small quantity in butter, and in various vegetable oils. Flaxseed oil 

 contains linolein ; castor oil, ricinolein, etc. 



We have already given the formulae of the principal 

 fats, but for our purposes, a better idea of their composi- 

 tion may be gathered from a centesimal statement, viz. : 



* Margarin, formerly thought to he a aistiuct fat, is a mixture of stearin and 

 palmitin. 



Digitized by Microsoft® 



