28 PROCEEDINGS OF THE AMERICAN ACADEIMT 



mercuric chlorides, which have respectively the formulas Co.,(XH3)j2 

 (SO,),(HgCl,), and Co,(NH,),,(SOJ,(PtCl,). ^ 



Chloro-platino-diromate of Luteocuhalt. — When neutral chromate 

 of luteocobalt is dissolved, and a solution of platinic chloride added, 

 brown-yellow crystals are obtained, which require a large quantity of 

 boiling water for solution, and are difficult to purify by recrystallization. 

 Of this salt : — 



0-G567 gr. gave 0-1920 gr. platinum, and 0-6026 gr. silver = 29-23% 

 platinum, and 30-16% chlorine. 



These numbers indicate the formula Co2(NH,)i2(CrO,)Cl,+2PtCl, 

 -|-o aq., which requires 29-33% platinum, and 31*55% chlorine. I do 

 not consider the constitution of this salt to be sufficiently established 

 by my analyses, though there is no a priori improbability in the for- 

 mula itself. 



Oxalo-auro-chloride of Luteocohalt. — When neutral oxalate of luteo- 

 cobalt is digested with a solution of auro-chloride of sodium, the salt 

 quickly changes its appearance as regards form and color, and a new 

 salt is formed, which is readily soluble in boiling water, and crystal- 

 lizes from the solution in long orange-yellow needles. The formula 

 of this salt is, — 



Co,(XH3),,(C,0,),Cl,+2AuCl3 + 40R„ 

 as appears from the following analyses : — 



0-5109 gr. gave 0-2107 gr. gold, and cobalt = 41-24%, and 0-1628 

 gr. gold = 31-86% gold, and by difference 9-38% cobalt. 



The formula Co,(NH3),,(C,0,),Cl,^-2AuCl,+40Il2 requires gold 

 31-56%, cobalt 9-47%. When neutral oxalate of luteocol):dt is dis- 

 solved in chlorhydric acid, and auro-chloride of sodium is addud, beau- 

 tiful yellow granular crystals are formed which contain no oxalic acid. 

 In this salt, — 



0-3042 gr. gave 0-1875 gr. SO^Co+Au containing 0-1043 gr. gold = 



34-25%, and 0-0832 gr. SO, Co = 10-41% cobalt. 

 0-6738 gr. gave 0-7591 gr. silver = 37-03% chlorine. 



The formula Co,(NH3)i2 01^+2 AuCl^ requires : — 



