OP ARTS AND SCIENCES. 17 



soluble ia hot than in cold water, and crystallizes as the solution cools, 

 thouijh not in well-defined forms. Its formula is — 



Co,(NH3)ioCl,-h2PtCl,+50H„ 



as the following analyses show : — 



9ai8 gr. gaveO-2899 gr. platinum, and 0-0868 gr. cobalt (by differ- 

 ence) = 31-12'5^ platinum, and 9-39^ cobalt = 40-51 %Pt-]-Co. 

 0-3040 gr. gave 0-1241 gr. platinum and cobalt = 40-79%. 



Heated to 140°C the salt lost 5-41% water, and was then decomposed 

 with a slight explosion, so that the whole of the water is not given off 

 below the temperature of decomposition. The formula requires : — 



Calculated. Found. 



Platinum, 31-15 31-12 



Cobalt, 9-28 9-39 



Water, 7-08 5-41 



When platinic chloride is added to a solution of chloride of roseoco- 

 balt, a dull-red crystalline salt in fine needles is formed, readily soluble 

 in hot water, and crystallizing from the solution unchanged. Of this 

 salt, — 



0-3766 gr. (reduced by zinc and SO^H^) gave 0-1087 gr. platinum and 

 0-3981 gr. silver = 28-86 ir;^ platinum and 35-55% chlorine. 



Tliese results correspond to the formula Co2(NH3)joCly-{-2PtCl^-}- 

 120FI.,, which requires 28-72% platinum, and 36-04% chlorine. 

 Braun states that by adding platinic chloride to a solution of a salt of 

 roseocobalt and free chlorhydric acid, he obtained a dark orange-red 

 crystalline precipitate, having the formula, as we should now write it, 

 3.Co2(NH.3)j|3Cly-)-4.PtCl^. I have never obtained any such salt ; and 

 as Braun's formula is based upon a determination of the sum of the 

 percentages of platinum and cobalt only, it cannot be regarded as even 

 probable. Genth and I have stated in the first part of this paper, that 

 chloride of roseocobalt f6rms with platinic chloride a salt which we 

 had not completely examined, but which appeared to have the formula 

 Co2(NH3)iyCl,;-[-3PtCl^-(-80H2. I have not obtained this salt again ; 

 but the following analyses will serve to show that we had some reason 

 for believing in its existence : — 



0-7593 gr. gave 0-3256 gr. platinum and cobalt = 42-88%. 



0-6155 gr. gave 0-3326 gr. platinum and SO^Co = 0-2182 gr. platinum 



and 0-1144 gr. SO^ Co = 35-45% platinum and 7-07% cobalt. 

 0-4809 gr. gave 0-7491 gr. AgCl = 38-50% cWorine. 



VOL. XI. (n. S. II.) 2 



