132 CHOLESTERIN. 



Preparation. Apart from the synthetic methods, it may readily be 

 obtained by the fermentation of malic 1 or tartaric 2 acids, which 

 are closely related to succinic, the former being hydroxy-succinic, 

 COOH.CH 2 .CH(OH).COOH, and the latter dihydroxy-succinic acid, 

 COOH. CH(OH).CH(OH).COOH. 



Some of the amido-derivatives of succinic acid, viz. asparagin and 

 aspartic acid, are of considerable interest ; they will be described later 

 on. 



Cholesterin. C^ H^ or C 25 H 42 3 . 



This substance is described here rather for the sake of convenience 

 than from its possessing any relationship to those which have preceded 

 it. 



Cholesterin is the only alcohol which occurs in the human body 

 in the free state. (The triatomic alcohol glycerin is always found 

 combined as in the fats : and cetyl-alcohol is obtained only from sperma- 

 ceti.) It is a glittering white crystalline substance, soapy to the touch, 

 crystallising in fine needles from its solution in ether, chloroform or 

 benzol j from its hot alcoholic solutions it is deposited on cooling in 

 rhombic tables ; this is the characteristic form and of great importance 

 for the identification of cholesterin. 



FIG. 5. CHOLESTERIN CRYSTALS. (After Funke.) 

 When dried it melts at 145, and distils in closed vessels at 360. 



1 Liebig, Ann. d. Glum. u. Pharm. Bd. LXX. (1849), Sn. 104, 363. 



2 Konig, Per. d. d. chem. Gesell. 1882, S. 172. 



3 Hesse, Ann. d. Chem. u. Pharm. Bd. cxcn. (1878), S. 175. Schulze u. Barbieri, 

 Jn. f. prakt. Chem. Bd. xxv. (1882), Sn. 159, 458. 



