( 488 ) 



often repeated warming- followed by rapid cooling. This substance 

 is about the best known example of this phenomenon. 



§ 6. If now we go on heating very cautiously, the larger flowing 

 crystals and also the smaller drops situated between them are seen 

 to move about rapidly ; the larger individuals, which consist mostly 

 of twins or quadruplets, are split up into a multitude of globular 

 drops and these, together with the smaller ones, disappear at a definite 

 temperature entirely in the isotropous liquid, which is now isotropous 

 in reality. The globules of the liquid rotate to the right and the left 

 under distortion of the mass, as may be observed from the spiral- 

 shaped transformation of the black cross. Sometimes, before the mass 

 becomes isotropous we may notice a temporary aggrandisement of 

 the plate-like flowing crystals at the expense of the smaller interjacent 

 globules; a result of the momentarily increased crystallisation-velocity 

 due to heating. 



$ 7. On cooling the isotropous fusion this is first differentiated 

 into an infinite number of the double-refracting liquid globulus, which 



here and Ihere amalgamate to the more plate-like flowing crystals. 

 On further cooling, these latter individuals remain in existence 

 notwithstanding the undercooling, while the little globules in the 

 meanwhile unite to the same kind of plate-hke individuals. This aggre- 

 gate, brilliant in higher interference colours becomes in course of time 

 thicker and thicker in consistency while the aggregation, owing 

 to an apparent splitting, becomes more and more finely granu- 

 lated. But even after the lapse of some hours, the phase remains 

 anisotropous-liquid as may be easily proved by shifting the mass and 

 by the pseudo-isotropous border, which commences to exhibit delicate, 

 double refracting' current-lines. In the end when the pseudo-isotropous 

 liquid has passed like the remainder into the same, almost completely 

 immobile aggregation of doubly-refracting individuals, it is, gradually, 

 transformed after a very long time into an aggregate of plates and 

 spherolite-like masses, which possess a strong double refraction. 



§ 8. If, after the lapse of some hours, the partially or completely 

 solidified mass is melted cautiously, we sometimes succeed, in the 

 case of the two valerates, in keeping the crystals of the phase S 

 (therefore the solid crystals) for a few minutes near the isotropous 

 fusion L at a temperature above the highest transition point. This 

 phenomenon is, therefore, again quite homologous to that first observed 

 by me with cholesterol-laurate and which might be described as a 



