28 PROCEEDINGS OF THE AMERICAN ACADEJIY 



mercuric chlorides, which have respectively the formulas Co^,(XH".)j2 

 (SO,),(IIgCl,), and Co,(NII,)„(SO,),(l'tClJ. 



Cliloro-jAatiuo-chromate of Lutcocohalt. — When neutral chromate 

 of luteocobalt is dissolved, and a solution of platiuic 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 : — 



0-6567 gr. gave 0-1920 gr. platinum, and 0-6026 gr. silver = 29-23 <% 

 platinum, and 30-16^ chlorine. 



These numbers indicate the formula Co2(NH3)j2(CrOJCl^-|-2PtCl4 

 -|-5 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 Luteocobalt. — 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,(NH3),,(aO,),Cl,+2AuCl3 + 40H„ 

 as appears from the following analyses : — 



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

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



The formula Co,(NH3)i2(C,0,),Cl2-h2AuCl3+40H2 requires gold 

 31-56%, cobalt 9-47%. When neutral oxalate of luteocobalt is dis- 

 solved in chlorliydric acid, and auro-chloride of sodium is added, beau- 

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

 In this salt, — 



0-3042 gr. gave 0-1875 gr. SO^Co-fAu 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),,Cl,+2AuCl3 requires : — 



