( 487 ) 



transformations, when observed microscopically, convey the impression 



of being more sudden than in the thermic observation. 



Still, the microscope completes the task of the thermometer in a 

 manner not to be undervalued, at it gives an insight into the structure 

 of the diverse phases and allows one to demonstrate their difference 

 or their identity. 



§ 5. If a little of the beautifully crystallised n-vahrate is carefully 



melted on an object glass, the substance, at a definite temperature 

 changes, apparently suddenly, into an aggregate of an enormous 

 number of globular, very large and strongly doubly-refracting liquid- 

 drops, which all exhibit the black cross of the spherolites x ) but can 

 flow really all the same. This condition may be rendered permanent 

 for a long time at will. But they may also amalgamate afterwards 

 to larger, plate-like, highly coloured liquid individuals, somewhat 

 resembling sharply limited crystals. These are frequently multiplets 

 of liquid drops; the demarcations between the separate individuals 

 vary constantly by changes in temperature. 



The isotropous border of the mass is very striking. By pressure 

 or by moving the covering glass, also by the sliding currents which 

 we can induce herein by changes in temperature, it may be readily 

 shown that this isotropous border, owing to a parallel orientation 

 of the liquid individuals, is only pseudo-isotropous and really identical 

 with the rest of the phase. Sometimes one may succeed even in 

 communicating this pseudo-isotropous aspect to the entire mass •) by 



] ) We can, however, often observe a slanting projection of the optical symmetry 

 axis, which gives the same impression as if we look perpendicularly to one of 

 the optical axes of a biaxial crystal, or on a mcnoxial crystal cut obliquely to 

 the optical axis. We observe at the same time coloured rings which exhibit an 

 elliptic form. It is very remarkable that, when the phase has become very viscous 

 on cooling, these ellipsoidal drops, provided with rings and slanting but mutually 

 parallel-directed axes may be kept for a long time in an apparently immobile condition 

 in the midst of the pseudo-isotropous or double-refracting liquid. They place them- 

 selveS mutually like little ellipsoidal magnets. 



However, I could observe, that these drops are often not. quite ellipsoidal, but 

 that they are sharply broken a little at the one side, just there, where the optical 

 axis is slanting. By turning the object-table, the axial point turns in the same 

 direction as the table, while the black line or cross is preserved. (Added in the 

 English translation Januari 1907). 



-) The anisotropous-liquid phase has, in the case of the two valerates, an extra- 

 ordinary tendency to place itself in this pseudo-isotropous condition. We can 

 observe this, because the border of the drop often moves inward with widening 

 of the isotropous-looking line. It is also remarkable to see how the tlowing crystals 

 when meeting an air bubble arrange themselves close together, normally on ihe 

 border thereof. 



