OP ARTS AND SCIENCES. 17 



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

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



Co,(NH3),„C]„+2PtCl,+50H.„ 



as the following analyses show : — 



9ai8 gr. gave 0-281)'.) gr. platinnm, and 0-08G8 gr. cobalt (by diff.T- 

 ence) =31-12'^ platinum, and 'J-3'.)«^ 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 



Col.alt, 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, — 



0-37GG gr. (reduced by zinc and SOJI^) gave 0-1087 gr. platinum and 

 0-3981 gr. silver = 28-86 f^ platinum and 35-55<^ chlorine. 



Tliese results correspond to the formula Co2(NH3)joClg-[-2PtCl^-|- 

 1201X2, which requires 28-72% platinum, and 3G-04% chlorine. 

 Braun states that by adding platinic clilocide 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„)jQCl^-|-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 forms with platinic chloride a salt which we 

 had not completely examined, but which apj^eared to have the formula 

 Co2(NH3)ioCl,.-l-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 = 0-2 182 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% chlorine. 



VOL. XI. (n. s. ii.) 2 



