303 



Beautiful, colourless, very lustrous and transparent crystals, which 

 allow very exact measurements. The substance was prepared fVom 

 ZnC/, and etliyknediainine in slight excess; it was recrystallised 

 from water. Analysis gave: 20 7o ^V, corresponding with a content 

 of 2 molecules of water. 



Monoclinic-prismatic. 

 rt:è:C = 0,9238: 1 : 0,6299 ; 

 /?=86°33'. 

 Forms observed: 6 = [010], commonly predominant and highly 

 lustrous, occasionally totally absent; n? = [lOOJ, well-developed and 

 always present; o = [111], yielding splendid reflexes; ?/i = [350], 

 lustrous, and when present, rather large; c=[001], small, often 

 absent, giving somewhat dull reflexes; ^ = [011] and ^=:[031], 

 very dimly reflecting; oj = [111], highly lustrous and well-developed. 

 The external form is that of hexagonally bordered, thick plates 

 parallel to [010], or that of short prisms parallel to the c-axis. 

 Angles- Observed- Calculated 



No distinct cleavability was found. 



On [010] is the angle of extinction 11° with respect to the c-axis ; 

 the plane of the optical axes is probably [010]. 



Laboratory for Inorganic and Physical Chemistry of the 

 University, Groningen, Holland. 



