( 295 ) 



212°. An addition of lupeol acetate from a previous preparation did 

 mil affect tin' melting point. II'. however, il was mixed with lupoid 

 or with lupeol which had heen healed for some time at 190° a 

 serious depression (about 20°) of the melting point could be observed. 

 The experiments described, therefore, prove convincingly that lupeol 

 (obtained from bresk is nol converted into lupeylene under the 

 circumstances mentioned by Jungfleisch and Leroux. 



w 



As lupeol might perhaps exist in two modifications, Dr. F. M. Jaeger, 

 lo whom I wish to convey my best thanks, was kind enough to 

 study the behaviour of lupeol on melting. Dr. Jaeger communicates 

 to the following particulars me: 



"If lupeol is melted to a singly -refracting liquid />. which takes 

 place very sharply, the mass, on cooling, solidities partly to an 



aggregate of broad pointed needles 

 A, glittering in high interference 

 colours, partly to a horny singly- 

 refracting mass A' , which fre- 

 quently exhibits globular sphero- 

 lites, resembling liquid droplets, 

 which aii- very feebly doubly -refracting. The needles A at once 

 show a tremendous number of transversal clefts, whilst the splendour 

 of the colours diminishes strongly; .1 passes here into a second 

 modification B, the common form of lupeol. Meanwhile the horny 

 mass has also hurst and exhibits here and there a strained double 

 refraction besides an increase in the 1111111110- of droplets, that is 

 to say, crystallisation nuclei in an embryonal condition. If heated 

 carefully for a moment, it crystallises into the needles A, which pass 

 immediately into B (by bursting etc.); the horny mass A' is iden- 

 tical with the needles A: it is .1 in a supercooled condition. 



The crystallisation velocity is here nearly =r 0, and by heating 

 it is increased to such an extent (owing to the diminution of the 

 internal friction etc.) that (he mass begins to crystallise. This is 

 a phenomenon well known to me; beautiful instances of crystal- 

 lisation on beating are usiiic acid and many cholesterol esters of 

 fatly acids. 



On remelting B, A is formed some times for a few short moments, 

 afterwards L. The two modifications therefore appear to be related 

 by enantiotropy." 



Utrecht, Org. Chem. Lab. Univers. 



