GLYCERINE. 243 



purity, by dissolving castor-oil in absolute alcohol, and passing 

 hydrochloric acid gas through the fluid ; at the end of the opera- 

 tion the compounds of the fatty acids with oxide of ethyl, which 

 have been produced, must be separated by means of water. The 

 aqueous fluid, on evaporation, leaves glycerine, which may be 

 entirely freed from adhering traces of the fatty ethers by being 

 shaken in ether. 



Tests. Glycerine could not be readily detected in animal 

 fluids unless we were able to obtain it in sufficient quantity to 

 admit of its being subjected to an elementary analysis; but this 

 would be hardly possible, since it would be difficult to obtain the 

 glycerine in a state of purity from the animal fluids. Fortunately, 

 however, acrolein is a substance with so intense and characteristic 

 an odour that this product of the decomposition of glycerine may 

 be employed as a test of its presence. The glycerine, separated in 

 as pure a state as possible, must be rapidly heated either alone or 

 with a little anhydrous phosphoric acid, when, if the glycerine be 

 much diluted, the peculiar and very disagreeable odour, not unlike 

 that developed by the wick of an expiring oil-lamp, is evolved with 

 sufficient distinctness. 



Physiological Relations. 



Occurrence. Glycerine has been recently discovered by Gobley* 

 in animal bodies. He first detected it in the yolk of the egg of the 

 common fowl in the form of phosphate of glycerine-ammonia, and 

 subsequently f in the same state of combination in the fats of the 

 brain. 



Origin. Regarding the source of the glycerine in the organism, 

 there can be no doubt that, in addition to the true fats the stearate, 

 margarate, and oleate of oxide of lipyl there are many fatty acids, 

 either free or in combination with alkalies, occurring in the animal 

 body. Since the combinations of the fatty acids and oxide of lipyl 

 are introduced into the animal body from without, we need not 

 wonder that glycerine, which is formed from oxide of lipyl during 

 the decomposition of the fats, is not found in far larger quantity 

 in this or that animal fluid. We have already directed attention 

 to the possibility (p. 56 and p. 103) that in the consumption and 

 gradual oxidation of the neutral fats, the oxide of lipyl, separated 

 as glycerine, is probably converted into lactic or even into metace- 

 tonic acid. Further investigations are, however, necessary before 



* Compt. rend. T. 21, pp. 766-769, et 988-992. 



t Journ. de Pharm. 3 Ser. T. 11, pp. 409-417, et T. 12, pp. 5-13. 



