OF ARTS AND SCIENCES. 19 



The formula Co,(NII,),„(SO,),,Cl2+PtCl, re<iuircs 35-4')%. The 

 very small quantity of the sulphate at my disposal prevented me from 

 making a more complete analysis ; but there can scarcely be a doubt as 

 to the constitution of the salt. 



Chloro-aurate of Roseocobalt. — Chloro-aurate of sodium produces 

 in a cold solution of the chloride of roseocobalt a beautiful bright 

 orange-red crystalline salt, which may be redissolved in hot water, and 

 recrystallized without sensible decomposition. This salt has the 

 formula, — 



Co,(NIL),,Cl,+2AuCl3+20II„ 



as appears from the following analyses : — 



0-5996 gr. gave 0-3674 gr. gold and SO^Co containing 0-2047 gr. 



gold = 10-33^ cobalt and 34-14% gold. 

 0-8900gr. gave 0-3080 gr. gold = 34-59%, and 1-0013 gr. silver = 



36-98% chlorine. 



The salt is soluble even in cold water ; the solution has a fine orange- 

 red color. The formula requires : — 



Calculated. Found. 



Cobalt, 10-31 10-33 



Gold, 34-44 34-37 (mean) 



Chlorine, 37-23 36-98 



The salt contains two atoms of water, which are not found in the cor- 

 responding salt of purpureocobalt. It is one of the most beautiful of 

 the whole series. 



Sulphato-chloro-aurate. — Chloro-aurate of sodium gives a beautiful 

 orange-red crystalline precipitate with soluble sulphate of roseocobalt. 

 The salt is but slightly soluble in cold water, and may be washed 

 without sensible loss. It requires much hot water for solution, but 

 dissolves without decomposition, and separates from the solution on 

 cooling in fine briglit-red crystals. The formula of this salt is, — 



Co,(NH3),o(SO,),Cl,+2AuCl3+40H„ 

 as the following analyses show : — 



0-4331 gr. gave 0-1389 gr. gold = 32-07%. 



0-3542 gr. gave 0-U73 gr. SO^Ba^z 0-1363 gr. SO^Ba. 



