( 196 ) 



This compound crystallises from 

 benzene in very large, colorless, iso- 

 metrical-developed crystals, which are 

 always twins and of exactly the same 

 form as that of the previous compound 

 with which this substance is isomor- 

 phous. 



The geometrical anomalies caused 

 by the curvature or angulation of the 

 planes are more considerable with this 

 derivative, than with the previous one; 

 the development of the crystals is less 

 perfect and they also exhibit a smaller 

 number of combining forms. From 

 ether and acetone we obtain besides 

 twin-crystals also single needles which 

 can be measured more accurately. 



The symmetry is monocllno-prismatic ; the axial relation is: 



a :^»:c = 0,5392:1 : 0,7574. 



ft z= 86''28'. 



Forms observed are: ;?? = jllOj and p = |120|, broad and lustrous; 

 c = {OÜl|, very lustrous and well developed; ;• = jlOlj, smaller 

 but properly measurable; h =z \0\()\, narrow and often absent. 



Fig. 4. 



A distinct cleavability was not observed. 



This substance also has a decided tendency to twin-formation 

 towards |102| as twin-plane; single crystals are rare. Owing to this 

 pecidiarity, the external resemblance of this isomer with the former 

 is increased in a high degree. It should be observed that these twins 

 and also those of the former substance often also show jOlOj and 



