26(3 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
rated solution. Now almost all known liquids possess this property, 
so that, to be consistent, they should be considered as crystallized, and, 
since they are isotropic, as belonging to the regular system. The three 
organic substances which form the subject of the paper are examples (at 
present the only ones known) of liquid crystals which are anisotropic. 
They are : — 
1. Azoxyphenetol. 
2. Azoxyanisol. 
'OCH, 
C 6 H 4 < 
c 6 h 4 < 
'N. 
>0 
T)CH : 
3. 
Compound of the composition 
The following observations apply to all three alike. 
The normal form of crystal drops — Crystals of the substance under 
examination, placed on the stage of the Microscope under a cover-glass, 
were melted and then allowed to cool again to the point of crystalliza- 
tion. On again warming and examining between crossed nicols, at a 
certain temperature (134° for azoxyphenetol, 116° for azoxyanisol, 
and 87° for the third substance), a sudden transformation into strongly 
doubly refracting crystals took place. These newly formed crystals 
preserved the same form as the first, but were seen by pressing down 
the cover-glass to be not really solid, but liquid. By warming still 
further, at a definite temperature (165° for azoxyphenetol, 134° for 
azoxyanisol, and 140° for the third substance), they passed into the 
ordinary isotropic liquid modification. In order to isolate the liquid 
crystals a solvent in the shape of Canada balsam was used. By then 
heating to a temperature above their point of fusion, and subsequently 
cooling, the crystal drops separated out from the solvent in perfect 
spheres, which in ordinary light showed peculiar shading effects, most 
of them like fig. 1 or fig. 2 (Plate V.). These figures really represent the 
same object in different positions. The shading effect is due to irregu- 
larities of refraction, like the “ Schlieren ” seen in amorphous bodies 
when examined under oblique illumination by Topler’s “Schlieren- 
apparatus.” * 
* Pogg. Ann., 127 (1866) p. 556. 
