Co, 



OF ARTS AND SCIENCES. 33 



Cobalt, 2 



Gold, 2 



Chlorine, 12 



In the first analysis the salt was reduced by zinc and dilute sulphuric 

 acid, the gold weighed directly, and the chlorine determined in the 

 filtrate. In the second, the salt was heated with sulphuric acid, and 

 the reduced gold separated from the cobaltic sulphate by dissolving the 

 latter in boiling water. The formula of the salt is 



Co,(NH3),,Cl«+2AuCl3, 

 or rationally 



NH3 — CI 



NH3 — NH,, — CI 



NH3 — NH3 — CI = AuClg 



NH,, — NH3 — CI = AUCI3 

 NHg — NH3— CI 

 NH3 — CI 



From the formula it appears that the salt is unsaturated, similar salts 

 containing four or six molecules of auric chloride being also possible. 



Chloro-hydrargyrates of Purpureocobalt. — When mercuric chloride 

 is added in excess to a solution of chloride of purpureocobalt, a rather 

 dull red salt separates in small needles, slightly soluble in cold water, 

 but much more easily soluble in hot water, especially in the presence 

 of free chlorhydric acid, and readily crystallizing from the hot solution. 

 This salt has the formula 



Co,(NH3),oCl,+ 6HgCl, 



as the following analyses show : — 



0-5884 gr. gave 0-3922 gr. Hg^CU^ 56-60 per cent mercury. 

 0-4409 gr. gave 0-4025 gr. silver = 30-00 per cent chlorine 



Calculated. Found. 



Mercury, 6 56-47 56-60 



Chlorine, 18 30-04 30-ii0 



When the chloride of purpureocobalt is in excess, or when the two 

 chlorides are mixed in the proper atomic proportions, another double 

 salt separates in very beautiful violet-colored prismatic crystals, which, 

 like the last-mentioned salt, are but slightly soluble in cold water, but 

 are much more soluble in boiling water, and crystallize from the solu- 

 tion on coolinor. This salt has the formula 



Co,(NH3),,Cl, + 4HgCl, 

 as the following analyses show : — 



VOL. X. (X. S. II.) 3 



