( 476 ) 



"pseudo-isotropous" (Lehmann) and is, in reality, not different from 

 A; only, the optical axes of the liquid crystals are all directed 

 perpendicularly to the glass-surface. The other cholesterol-esters also 

 exhibit this phenomenon. On further cooling, this phase A crystal- 

 lises like the pseudo-isotropous border to a similar mostly spherolitic 

 crystalline mass «S. 



Between the spherolites one often sees currents of the pseudo- 

 isotropous border liquid. 



If now the entire mass is allowed to solidify to 5", and then again 

 is melted carefully, it is at once transformed into the liquid A , recog- 

 nisable by its high interference colours and its slow currents. Then, 

 there appears suddenly a new. greyish liquid B, consisting of smaller 

 individuals with a less powerful double refraction, which after a 

 short time is replaced suddenly by the isotropous fusion L. If L is 

 now cooled again, it is .1 which appears at once and not the phase B. 



Only a very treble, greyish Hash of light, lasting only for a 

 moment, points to a rapid passing of the phase B ; it cannot, however, 

 be completely realised now. On further cooling, S is formed sud- 

 denly, sometimes in plate-like crystals. When once crystallisation has 

 set in, S will not melt when the mass is heated, as might have been 

 expected, but actually increase in size of the crystals occurs, and 

 the velocity of crystallisation is now many # times increased. It musl 

 be remarked that the growing Hal needles of S" drive before them, 

 at their borders, the liquid phase .1 amid violen! currents. If the 

 heating is now continued a little longer, we may notice sometimes, 

 that whilst the little plates of «S remain partly in existence, A passes 

 first into the grey phase B, which then is converted into the isotropous 

 mass L. We then have adjacent to L the solid phase S, which 

 therefore, may be heated above its melting point, before disappearing 

 finally into the isotropous fusion L. 



All this shows, that the laurate possesses three stable liquid phases 

 and also that the isotropous fusion being coled, B is always passed 

 over, but is realised when the solid phase is heated. All this is repre- 

 sented in the annexed ^-/-diagram ; the arrows, therefore, indicate 

 the order of the phases traversed on melting and on cooling. The 

 phase A in its quasi immovable period maj~ be kept a long time 

 solid at the temperature of the room, and may be considerably under- 

 cooled before it passes into S. Notwithstanding its apparently solid 

 appearance in that undercooled condition, A is still a tenaceous, 

 thick liquid, as I could prove by stirring the mass with a thin 

 platinum wire. 



The point (7 3 ) agrees with the opalescence which occurs when 



