LIPOIDS 141 



Concentration cause precipitation. This is in thorough accord with 

 the solubility of such substances in fats. 



Lecithin acts towards colloids and suspensions (ferric hydroxid, 

 mastic suspension) like any other colloid which migrates to the 

 anode. Similarly charged colloids cause no precipitation (and 

 lecithin may even act as a protective colloid for mastic) ; oppositely 

 charged colloids produce flocculation in suitable mixtures (ferric- 

 oxid hydrosol). Saponin clears lecithin suspensions. 



Alcoholic lecithin solutions are much more stable in the presence of 

 salts than aqueous solutions. Mercuric chlorid is an exception. 

 Alcoholic lecithin solutions protect some other colloids, e.g., albumoses, 

 from the precipitating action of alcohol. (L. MICHAELIS and P. 



RONA* 1 .) 



Ethereal lecithin solutions cause some otherwise insoluble sub- 

 stance to dissolve in ether (e.g., NaCl and grape sugar). This prop- 

 erty is evidently due to the fact that in ethereal solution, lecithin 

 has a great capacity for taking up water. 



Cholesterin, according to the investigations of O. FORGES and E. 

 NEUBAUER,* is a hydrophobe colloid. Its aqueous emulsion behaves 

 like a mastic suspension in the presence of a large variety of salts. 

 The same is true for its behavior with other colloids. In neutral 

 solution it is precipitated by certain proportions of albumin and 

 saponin. Lecithin may act as a protective colloid for cholesterin. 

 Cholesterin forms a true solution in alcohol and ether, and in such 

 solutions exhibits no colloid precipitation reactions. 



