456 CHEMISTRY OF THE TISSUES. 



This is known by evaporating a small quantity of the ether 

 eacli time it is taken from the brain. Put the ether aside; ex- 

 tract the brain with hot alcohol several times, and filter it hot. 

 On cooling, cerebrin will crystallize out, mixed with lecithin. 



69. Cerebrin. Purification. Filter off the alcohol from 

 the crystals, wash them with cold ether, and boil them for an 

 hour with baryta water. Pass CO, through the liquid to pre- 

 cipitate the excess of baryta ; filter, and wash the precipitate 

 first witli cold water and then with cold alcohol. Put the pre- 

 cipitate in a beaker with alcohol and heat it, to extract the 

 cerebrin from it, an,d filter it hot. On cooling, crystals of 

 cerebrin will be deposited, which should be again dissolved in 

 hot ak-ohol, allowed to crystallize out again, washed with ether, 

 rind dried at a moderate temperature. 



(Vrebriu forms a white hygroscopic powder. Put a little on 

 a piece of platinum foil and heat it. It will become brown, 

 melt, MIM! then burn. 



I-'roin the mode of preparation, it is evident that it is inso- 

 luble in cold but soluble in hot alcohol, and that it is not de- 

 stroyed by boiling with baryta water. 



Put it in water. It will slowly swell up, somewhat like 

 starch. 



70. Lecithin. Add to the alcoholic extract (a) a solution 

 Of platinum chloride, acidified with hydrochloric acid. A vel- 

 low (loceuleiit precipitate of lecithin platinum chloride will 

 fall. Filter, and dissolve the precipitate in ether; pass hydro- 

 gen sulphide through the solution to precipitate the platinum. 

 Kilter and evaporate. Lecithin chloride will remain a waxy 

 mass. 



Decomposition, When treated with acids or with boiling 

 baryta water it is decomposed, and yields glycerophosphoric 

 acid, iieurin, and fatty acids. 



Dissolve some lecithin chloride in alcohol and pour it into 

 boiling baryta water. It will be decomposed, and a smeary 

 precipitate will fall. 



71. Neurin. -Filter; pass C0. 2 through the filtrate to re- 

 move the baryta: lilter; evaporate to dryness; extract with 

 alcohol Add to the alcoholic extract platinum chloride, and 

 a precipitate of neurin platinum ehlori Ie will fall. The pla- 

 tinum may l.e removed by hydrogen sulphide and the neurin 

 chloride obtained, but it is with difficulty crystallizable. 



