38 



RESEARCHES ON THE 



According to Prof. Dana's measurements, the acicular crystals belong to the 

 monoclinic system, so far as it is possible to determine. The crystals are usually 

 hollow and much striated longitudinally. The observed forms are I, ii and 0, and 

 the angles 



Fig. 10. 

 1:1= 101° 10' 



I : ii = 143° 50' 



= 114° 15' 



Twin crystals are frequent, the composition being parallel to the plane O. The 

 salt is very slightly soluble in cold water, but dissolves in much boiling water, from 

 which it separates on cooling. When gently heated in a porcelain crucible it gives 

 off ammonia and chloride of ammonium, and becomes green. The green mass, on 

 solution in water, gives globular aggregations of minute crystals of a buff color, 

 which may be a new salt, but which we have not specially examined. Zinc 

 decomposes the chlorplatinate of Luteocobalt only by very long boiling in an acid 

 solution, metallic platinum being separated as a black powder, while chlorides of 

 cobalt and ammonium are formed. 



The formula of the orange salt is 



6NH 3 .Co 2 Cl 3 + 3PtCl 2 + 6HO 

 as the following analyses show : 



1.220 grs. gave 0.4321 grs. metallic platinum = 35.41 per cent. 

 1.220 grs. gave 0.2261 grs. sulphate of cobalt = 1.05 per cent, cobalt. 





Eqs. 



Calculated. 



Found 



Cobalt . 



. 2 



1.10 



1.05 



Platinum 



. 2 



35.64 



35.41 



The formula of the yellow salt is 



6NH 3 .Co 2 Cl 3 + 3PtCl 2 + 21HO 



as appears from the analyses : 



0.2638 grs. gave 0.0822 grs. metallic platinum = 31.16 per cent. 



0.4449 grs. gave 0.6031 grs. chloride of silver = 33.54 per cent, chlorine. 



Eqs. Calculated. Found. 



Platinum 

 Chlorine . 



30.99 

 33.42 



31.16 

 33.54 



Eogojski found in this salt but one and a half equivalents of water, but bis 

 analyses are not very satisfactory, giving a large excess of platinum, hydrogen, and 

 cobalt. 



