59 



A distinct cleavage was not found. 



On {100} and {001 1 diagonal extinction. 



The apecific gravity of the crystals was determined at 25° C. pjcnome- 



25° 

 trically to be: fl~=:l. 709; the molecular volume is thus 497.64. 



Topical parameters •. ■/ : tji ; w = 6,6037 : 8,1740 : 9.2194. 



The compound does not change the direction of the plane of 

 polarisation of the incident light. 



VI. Laevoyyratorij LiUeo-Triethylenedlamine-CobaltMiitrate. 

 Formula : \Co [Aein)^\ (NO,),. 



The compound was prepared from the bromide by means of 

 silvernitrate in small excess and at lower temperature; after sepa- 

 rating from the silverbromide, the solution obtained was concentrated 

 on the waterbatli. From this solution, which thus contained a slight 

 excess of silvernitrate, big, dark-red crystals were obtained, which 

 gave splendid images, and made very accurate measurements possible. 



The crystals, which have the habit of thick, trapezohedrically or 

 pentagonally bounded plates, are usually developed parallel to oppo- 

 site faces of the prism. They are extraordinarily rich in faces, and 

 geometrically very well built; commonly the faces of the forms 

 Oilj, {021i, I211J and {OlOj, are only partially present, a fact, which 

 in connection with the peculiar distortion of the crystals, often 

 impedes appreciably the exact crystallogi-aphical analyses of them. 



Rhonibic-bkpJienoidic. 



a:b: r = 0.8647 : 1 : 0,5983. 



Observed Forms: a := [100], well developed and giving beautiful 

 images; m = {ilOj; larger than a, giving good reflections; )'^|101}, 

 somewhat smaller than m, but in most cases equally well developed ; 

 0= {lllj, giving good images and relatively large ; s = {211 j narrower, 

 but retlecting well; (j = \0H\ and /j:={021j, usually with only 

 half the number of their faces present, but developed rather largely ; 

 /; = {010}, narrower than a and retlecting well. 



