( 13B ) 



rent ways, fluctuates between 114° and 118°. A furtlier investigation 

 will be necessary to see what really takes place here. 



Rhomhic-bipyramidal. 



a :^» = 0,6596:1. 

 The relation h : c cannot be determined, for want of the necessary 

 terminal planes. 



Forms observed: ??i = jllOj, broad and lustrous; c =: jOOlj, very 

 sharply reflecting; « = jlOOj, narrow, well reflecting; ^:> =: |310|, 

 very narrow and yielding bad reflexes. 



Measured: Calcidated: 

 rt : 771 = (100) : (110) = * 33°24i' — 



m : m = (110) : (TlO) = 113 lli 113° 11' 



m-.c = (110) : (001) = 90 1 90 



m:p =(110): (310)= 20 17 (about) 21 

 ^:« =(310): (100)= 13 2 (about) 12 24 

 Perfectly cleavable towards jOOlj. 



The optical axial plane is jOOlj ; the first diagonal is the «-axis. 

 The apparent axial angle is in «-monobromonaphtalene about 86°; 

 extraordinary strong dispersion with q > v, round the first bissectrix. 

 Orientated extinction everywhere in the vertical zone. 



The sp. gr. of the needles is 1,601, at 19°; the equivalent 

 volume = 187,32. 



6. 1-2-4-Dinitro-Methyl-Pheiiylcarbamic Ethyl-ester. 

 C, H3 (N0jr4) . (N0,)c2) . N(,) (CH,) . CO . (C.H^) ; m. p. 112° C. 



This compound crystallises 

 from a mixture of benzene and 

 ligroine in the form of large, 

 corlourless, very lustrous crystals 

 represented in fig 8. 

 Monodino-prismatic. 

 a: ^':c=0,6525: 1:0,7035. 

 ^=69°59'. 

 Forms observed : c = jOOlj, 

 predominating and very lustrous; 

 h = jOlOj, about as broad as c 

 and sharply reflecting -,111=1 {llOj, 

 well reflecting and properly 

 developed, sometimes with deli- 

 cate striping parallel to m:C\ 

 q = {Ollj, narrower but readily 

 measurable ; r = |10i|, very dis- 

 tinctly developed and yielding 



Fig. 8. 



