IL'1' NEUTRAL FATS. 



Olein (Tri-olein). C 8 H 6 (C 17 H 33 . C0.0) 8 . 



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. 



Preparation. From olive oil, either by cooling to O C. and 

 pressing out the olein that remains fluid, or by dissolving in hot 

 alcohol and cooling, when the olein remains in solution while the 

 other fats crystallise out. 



The fats which occur in the animal body are mixtures of the 

 above three substances in varying proportions. The normal fat of 

 each animal or class of animals is however characterised by the 

 constant preponderance of one of the three ; thus in the fat of 

 man and carnivora palmitin is in excess over the other two. In 

 the fat of herbivora stearin predominates, and in that of fishes 

 olein. Butter contains, in addition to the above, several fats 

 formed by the union of glycerin with the radicles of the lower 

 acids of the acetic series. 



There is no doubt that a large part of the fat laid on in the 

 animal body during fattening cannot be accounted for by the fat 

 given in the food, and must hence arise from a conversion of proteids 

 or carbohydrates into fat. (See 506, 507.) The question as to 

 how the storage arises from these food-stuffs is one which has 

 given rise to a prolonged controversy. On the one hand Voit 

 and his followers urged that although carbohydrates do lead to a 

 rapid storing of fat in the body, they do so not directly by being 

 themselves converted into fat, but indirectly ,by protecting the 

 proteids from the metabolism they would otherwise have under- 

 gone. According to this view fat is formed from proteids only. 

 Lawes and Gilbert on the other hand took the view that carbo- 

 hydrates are directly converted into fat. While there is no doubt 

 that proteids can give rise directly to fat as shown by the storage 

 of fat during "nitrogenous equilibrium" (see 522), there is 

 also now equally no doubt that carbohydrates can lead to a direct 

 storage of fat by being themselves converted into fat. This is 

 the incontrovertible outcome of the most recent experiments, 

 which have proved that with a diet rich in carbohydrates, so that 

 the. storage of fat is sufficiently rapid, more fat is laid on than 

 could possibly have been formed from the proteids in the food 

 given. 1 



1 Meissl u. Strohmer, Sitzb. d. Wien. Akad. Bd. LXXXVIII. 1883, IIL Abth. July. 

 Tscherwinskv, Landwirth. Versuchsstat. Bd. xxix. (1883J, S 317. Chaniewski, /K. 

 f. Bid. Bd.'xx. (1884), S. 179. Rubner, Ibid. Bd. xxii. (1886), S. 272. Munk, 

 Vircnow's Arch. Bd. ci. (1885), S. 91. Biol. Centralb. Bd. v. (1885-86), S. 316. See 

 also Voit, Ibid. Bd. vi. (1886-87), S. 243. 



