299 



Fo7-nis observed: a = [100], predominant and splendidly reflecting; 

 c=r001j, smaller, often completely absent, but very liistrons; 

 6 = [010], small, well reflecting; o = [Jll], somewhat broader 

 than to = [111], perfectly reflecting. The external habit is flattened 

 parallel to [100], with a slight elongation parallel to (he b-, or 



the c'-axis. 



Angles : Observed : Calculated : 



No distinct cleavability was observed. 



The crystals are distinctly dichroitic: on a for vibrations parallel 

 to the c-axis : orange-yellow, for those perpendicular to them : 

 lemon-yellow. The optical axial plane is [010]; one optical axis is 

 almost perpendicular to a. Extremely strong dispersion, with q <^v. 



\ 9. Racemic CIS -DiNiTRo-DiETHYLENEDiAMiNE-CoBALTi- Nitrite. 



{Flavo-QdAi). 



Co 



{No,\ 



m. 



rH. 



Fig. 7. 



Racemic cisDinitro- 



diethylenediamine-Gobalti- 



Nitrile. 



{Eine)^ 



Dark coloured crystals, which in their 

 external aspect, are highly analogous to 

 those of the corresponding ^ran.f-derivative. 

 They are very beautifully developed, and 

 possess constant angular values. 

 Monoclinic-prismatic . 

 a:b:c = 0,7382 : 1 : 0,9094; 

 /? = 82°57'. 

 Forms observed : m = [1 1 0], and b = [010], 

 large and very lustrous; o=:[lll], large, 

 perfectly reflecting; to = 1223], small but 

 well reflecting; c = [001], small, giving 

 good reflexes. The external habit is prismatic 

 parallel to the c-axis, and commonly some- 

 what flattened parallel to [010]. Occasionally 

 [010] is absent, in other cases, however, 

 the same is true for [223]. 



20* 



