( 135 ) 



Fig. 9. 



m : m = (110) 

 m:q = (110) 



q:q = (Oil) 

 m : b = (110) 



b:q = (010) 

 m:^ =(110) 

 ?/i : <; = (110) 



o:q = (I2i) 



(/ : »l = (Oil) 

 m : a = (110) 



The crystals whicl» have been meas- 

 ured are derived from a mixture of 

 benzene and Hgroine. 



Delicate, very transparent, flat, pale 

 sherry-coloured needles which possess 

 a strong lustre. 



Monodino-prisma tic. 



a: 6 :c = 0,9759:1 : 0,3929 



|3=67°7'. 



Forms observed : b = jOlOj, yielding- 

 ideal reflexes and well developed : 

 = |Ï21|, a = |100|, and c = jOOlj, 

 very narrow and dull ; in z= jllOj, 

 broad and very lustrous; ^ i= jOllj, 

 well developed and yielding sharp 

 reflexes; an orthodome jhokj is indi- 

 cated but not measurable. The needles 

 are elongated towards the c-axis and 

 somewhat flattened towards jOlOj. 



Measured : 



(110) = *83° 55' 



(01J) = *60 2 



(0llj = *39 48 



(010)= 48 3 



(011)= 70 6 



(Oil) = 119 58 



(121)= 64 46 



(011)= 27 32 



(llO)= 87 42 



(100)= 41 57 



Calculated: 



A distinct cleavability was not observed. 



The angle of extinction on b is 9° with regard to the vertical 

 axis, in the acute angle a:c; on ir. it is about 6|°. 



In oil of cloves, solution figures w^ere obtained as represented in 

 fig. 8; they are in accordance with the found symmetry. 



The sp.' gr. of the crystals is = 1,471 at 14° ; the equivalent 

 volume = 194,42. 



Topical axes: x = »P ••«> = 7,9976 : 8,1950 : 3,2198. 



