( 79 ) 



§ 2. In the lirst place the esters of cholesterol and phytosterol 

 had to be prepared. 



The cholesterol nsed, after being repeatedly recrjstallised from 

 absolute alcohol + ether, melted sharply at 149°. 2. The phyto- 

 sterol was prepared by Merck, by Hesse's^) method from Calabar 

 fat, and also recrystallised. It melted at 137°. A microscopic test did 

 not reveal in either specimen any inhomogeneous parts. 



First of all, I undertook the crystallographic investigation of the two 

 substances. The result agrees completely with the data given by Mügge, 

 to which I refer. I have not, up to the present, obtained any measu- 

 rable crystals ; on account of the optical properties, cholesterol can 

 possess only triclinic, and phytosterol only monoclinic symmetry. 



Although an expert crystallographer will have no difficulty in 

 microscopically distinguishing between the two substances, the crystals 

 deposited from solvents are, however, so much alike that a less expe- 

 rienced analyst may easily make a mistake. I, therefore, thought it 

 of practical importance to find a better way for their identification 

 with the microscope. 



This was found to be a very simple matter, if the crystals are 

 allowed to form on the object-glass by fusion and solidification, 

 instead of being deposited from solvents. Figs. 1 and 2 show the 

 way in which the solidification of the two substances takes place. 



Fig. 1. 



Cholesterol, 



fused and then solidified. 



Fig. 2. 



Phytosterol, 



fused and solidified by cooling 



Phytosterol crystallises in conglomerate spherolites. Between crossed 

 nicols they exhibit a vivid display of colours and each of them is 



'j Hesse, Annal. der Chemie, 192. 175. 



