50 



chlorocobalticldoride : \ Co 



Cl 



Cl,, witli three molecules of tri- 



ethylenediamine for a considerable time, and precipitating the compound 

 with sodiumbromide. 



A. The salt prepared by the metiiod indicated sub 'J is deposited 

 from the yellow-brown solutions as hexagonal plates of red-brown 

 or orange colour, or in the shape of hexagonal, short prisms, (fig Aa 

 and lb). 



Pscudo-dltrigonnl-scalenoëdrical, but |)i'obably really monoclinic 



a:c = l: 0.6794. 

 The compound is alinost perfectly isomorphous with the corre- 

 S|)onding chloride; however the cleavage differs in the two salts. 



Ohsei'ved Forms: r=i;{0001j, most prominent and giving good 

 images; ?/( ^ jlOlOi, often very well developed, shows however in 

 most cases broken faces, giving multiple reflections; r = jl011!, 

 sometimes small, but occasionally rather large; r' = |1011}, often 

 absent, several times very narrow, and in rare cases as well developed 

 as r \ perhaps .s- = |426;^i, occasionally visible as an extremely 

 nari'ow blunting. 



Anyvlar Val lies : Measured: Calculated : 

 r : « = (10Tl):(0001) =*38°7' — 



r : m = (lOTl) : (lOÜ») = 5 1 t,0 51o53' 

 ;// : m = (lOTO) : (OUO) = (SO 1^ (JO U 

 <■ : ,<; -- (0001) : (42ÏÏ3) — ca. r)4o 54 9 

 ,• : r = (10Tl);(ll01)= — '34 38 



Fig. 1. 

 Racemic Trielhylenediamine-Gobaltibromide. 



A perfect cleavage occurs parallel to {0001 j. Plates perpendicular 

 to the c-axis are however completely dark in no situation between 

 crossed nicols, if the light is polarized parallel. Occasionally they 

 appear to be composed of lamellae parallel to |0001j, like the well- 

 known mica-piles of Reusch and Mai.la-kd, as might also be proved 

 perhaps by the often observed anomalies of the angular values. 



The crystals are optically-uniaxial ; the birefringence is of a negative 

 character. They do not show a rotatory polarisation ; their dichroisra 



