OF ARTS AND SCIENCES. 25 



process. I mixed one molecule of chloride of purpureocobalt, and one 

 of nitrate of xanthocobalt, in the hope of obtaining a salt with the 

 formula Co2(NH3)io(NO,)(N03)2Cl3, since 



Co,(NH3),oCle+ Co,(NH3),„(NO,),(N03),= 

 2Co,(NH3),,(NO,)(x\03),C]3. 



After boiling the mixture with a little free acetic acid, the solution 

 deposited, on cooling, deep orange-red — apparentljt homogeneous — • 

 crystals. Of these 



0-314O gr. gave 0-1746 gr. SO^ Co = 21-1.3 per cent cobalt. 

 0-9203 gr. gave 0-5080 gr. silver = 17-99 per cent chlorine. 



The formula Co^{::iUs)io(^0^){:^0,).,C\s requires 20.90 cobalt, and 

 18-86 per cent chlorine. The analyses seem to show that a salt 

 having the composition given may exist. On recrystallization, the 

 salt was more or less completely decomposed, as the following analyses 

 show : — 



0-2125.gr. gave 0-1161 gr. SO^Co = 20-80 per cent cobalt. 



0-5933 gr. gave 0-2470 gr. silver = 13-70 per cent chlorine. 



0-7888 gr. gave 0*3308 gr. silver = 13-78 per cent chlorine. 



These numbers approximate to those required by the formula, 

 Co2(NHg)io(N02)2(N03)2Cl„. I attempted in like manner to form 

 salts synthetically by mixing other salts in the proportions indicated 

 by the equations : — 



Co2(NH3),„(N02)e + Co2(NH3),,Cls = Co2(NH,),„(N02)3Cl3. 



Co2(NH3),o(NO,,)« + Co2(NH3)„(N02)2(N03),= 



Co2(NH3),„(xN02)(N03),. 



The experiments led, however, to no definite results. 



The chloro-nitrate above described is the salt to which I, at one time, 

 attributed the formula 



Co,(NH3),o(N02),Cl2 + 20H2, 



and which I regarded as the chloride of a special radical, " flavo-cobalt," 

 Co2(NH3),„(NO.,)^. The mere analyses can hardly distinguish with 

 certainty between the two formulas, and I w^as for some time misled 

 by an erroneous interpretation of my results. The compounds of 

 cobalt containing ammonia and nitroxyl, NO^, have in general the 

 same color, and differ but little in solubility, so that it is extremely 

 difficult to separate them ; and in my analyses of what I believed to be 

 the sulphate and nitrate of the same base, I had undoubtedly to deal 



