OP ARTS AND SCIENCES. 23 



With potassic ferrocyanide it gives the characteristic red prismatic 



crystals of 



Co2(NIL),„(N02)oFeCys + 6OH2 ; 



and with amnionic oxahite, oxalate of xanthocobalt, 



Co,(NH3)i„(N02)2(CA)2, 

 the reactions being too obvious to require explanation by equations. 



As it is difficult to prevent the action of the alkaline nitrites upon 

 chloride of purpureocobalt from going too far and decomposing the 

 new salt first formed, I had recourse to a different mode of prepara- 

 tion, by which the salt can be prepared in any quantity and with the 

 greatest facility. A hot solution containing one molecule of chloride 

 of xanthocobalt was mixed with a solution containing one molecule of 

 nitrate of xanthocobalt. On cooling, the chloro-nitrate crystallized in 

 beautiful prismatic forms. In this case we have 



Co,(NH3),„(NO,).Cl, + Co,(NH3), „(N0,),(N03),= 

 2Co,(NH3),,(N02)2(N03),Cl2. 

 Of the crystals so formed, 



0-6203 gr. gave 0-3310 gr. €080^ = 20-31 per cent cobalt. 

 0-9268 gr. gave 0-3450 gr. silver = 12-24 per cent chlorine. 



The formula requires 20-51 per cent cobalt and 12-34 per cent chlorine. 

 A portion of the crystallized salt was dissolved and precipitated by 

 argentic nitrate. The filtrate from AgCl gave on evaporation crystals 

 of nitrate of xanthocobalt, in which 



0-2972 gr. gave 0-1469 gr. CoSO^ = 18-81 per cent cobalt. 



The formula of the nitrate requires 18-73 per cent. These results 

 leave no doubt as to the constitution and true relations of the chloro- 

 nitrate. 



Gold Salt. — When the chloro-nitrate is dissolved and a solution of 

 aurochloride of sodium, AuCl^Na, is added in excess, long prismatic 

 wine-yellow crystals are formed. Of these crystals, 



0-8564 gr. decomposed by zinc and sulphuric acid gave 0-6300 gr. silver 

 = 24-16 per cent chlorine and 0-2858 gr. gold = 33-36 per cent. 



0-4084 gr. gave 0*1770 gr. Au -|- Co = 43-34 per cent and by difference 

 9-98 per cent cobalt. 

 The formula, Co2(NH3),o(N02)2(N03)2Cl2+ 2AUCI3, requires : — 



Found. 



Cobalt 9-98 9-98 



Gold 33-33 33-36 



Chlorine 24-03 24.16 



