( 484 ) 



could hardly I te realised up to the present in the other known sub- 

 stances. They also exhibit enormous phenomena of retardation in their 

 diverse transitions and often a typical irreversibility thereof, of 

 which I will now communicate some particulars. 



§ 2. Thermometrical behaviour of the fatty «-phytosterol- 

 esters. 



A tt-Phytosterol-n.-Butyrate, oh very slowly raising the temperature, 

 melts at 89°. 5 to a turbid, doubly-refracting liquid A, which at first 

 is very viscous but rapidly becomes thinner and is converted, at 

 90°. 6, into a clear isotropous fusion L of the consistency of glycerol. 



On cooling- the same carefully, the thermometer falls gradually 

 while the isotropous liquid thickens more and more but remains 

 quite clear. At 80° the whole mass crystallises all at once to small 

 crystals N with so great a caloric effect that the thermometer goes 

 n[) to 85°. There is no question now of anisotropous liquid phases 

 at all. These two experiments may he repeated at will but' always 

 with the same result. As to the nature of tin 1 turbid phase, compare 

 ■micro-physical behaviour". 



If the isotropous fusion is suddenly cooled in cold water, a bluish- 

 Liiv\ coloration appears and a soft, doubly-refracting mass is obtained, 

 which does not become crystalline until after a very long time. 



I). a-Phytosterol-Isobutyrate, when treated in the same manner, 

 melts at 101°.4 to a glycerol-like, turbid, doubly-refracting liquid A, 

 which gradually assumes the consistency of paraflin-oil and is con- 

 verted at about 103°. 2, apparently continuously, into a clear fusion A. 



If this is cooled, it certainly becomes gradually thicker but it 

 still remains quite clear and isotropous. 



At 80°. 4 it becomes turbid and doubly-refracting; this phase is 

 identical with A, and it has the consistency of glycerol ; at 73° it 

 has become as thick as butter, and at 66" the thermometer can be 

 moved only with difficulty, whilst it may now be drawn into sticky, 

 doubly-refracting threads. At 65° the thermometer suddenly goes up 

 to 68\8 and the mass crystallises in long, delicate needles S. 



On rapid cooling of the fused mass, this is converted into a turbid, 

 greasy looking, doubly-refracting mass, which crystallises but very 

 slowly : no colour-phenomena occur. 



C. a-Phytosterol-n.- Valerate melts, when in the crystallised condi- 

 tion, at an uncertain temperature. At about 48 3 , the substance com- 

 mences to soften visibly, at 54 D its consistency is that of thick butter, 

 at 80 D it is somewhat thinner, at 85° it is actually liquid, but still 

 turbid and doubly-retracting. All these transformations proceed quite 



