1230 NEUTRAL FATS. 



ether, chloroform, benzene, etc. ; they also dissolve one another. 

 They are neutral bodies, colourless and tasteless when pure ; 

 they are not capable of being distilled without undergoing 

 decomposition, and yield as a result of this decomposition, solid 

 and liquid hydrocarbons, water, fatty acids, and a peculiar 

 substance, acrolein, resulting from the decomposition of the 

 glycerin. (See below.) 



They possess no action on polarized light. 



They may readily be decomposed into glycerin and their 

 respective fatty acids by the action of caustic alkalis or of 

 superheated steam. 



Palmitin (Tri-palmitin). C 3 H 5 (C 15 H 31 . CO . O) 3 . 



Palmitin is but slightly soluble in alcohol either cold or 

 hot, readily so in ether, from which, when pure, it crystallizes 

 in fine needles ; if mixed with stearin, it generally forms shape- 

 less lumps, although the mixture may at times assume a crys- 

 talline form, and was then regarded as a distinct body, namely 

 margariu. When pure it melts at 62 and solidities again 

 at 45. 



It is most conveniently obtained from palm-oil by removing 

 the free palmitic and oleic acids by alcohol and repeatedly crys- 

 tallizing the residue from ether. 



Stearin (Tri-stearin) . C 3 H 5 (C 17 H 36 . CO . O) 3 . 



This is the hardest and least fusible of the ordinary fats of 

 the body ; is also the least soluble, and hence is the first to 

 crystallize out from solutions of the mixed fats. Readily sol- 

 uble in ether and in boiling alcohol. It crystallizes usually in 

 square tables or glittering plates. It presents peculiarities in 

 its fusing points, melting first at 55 then solidifying as the 

 temperature is further raised and melting finally and perma- 

 nently at 71. 



Preparation. From mutton suet, its separation from palmitin 

 and olein being effected by repeated crystallization from ether, 

 stearin being the least soluble. It is however very difficult to 

 obtain it pure by this process. 



Olein (Tri-olein). C 3 H 5 (C 17 H 33 . CO . O) 3 . 



Is obtained with difficulty in the pure state, and is then 

 fluid at ordinary temperatures. It is somewhat soluble in 

 alcohol, very soluble in ether. It readily undergoes oxidation 

 when exposed to the air, and is converted by mere traces of 

 nitrous acid into a solid isomeric fat tri-elaidin. Olein is 

 saponified with much greater difficulty than are palmitin and 

 stearin. 



