210 



REPORT 1877. 



also graphically represented by the curves in the diagrams of each series of 

 salts given below. 



The method generally employed in the determination of the nickel and 

 rx>balt was that of Liebig, viz. by treatment with HCy and KHO to obtain 

 the cyanides hi solution, precipitating the nickel as NiO with mercuric 

 oxide and separating the cobalt from the filtrate by mercurous nitrate, the 

 mercurous cobalticyanide being ignited and weighed as Co 3 4 . It may be 

 mentioned that in many cases the determinations by this method were 

 checked by others conducted by separating the cobalt as double nitrite of 

 cobalt and potassium, incinerating this body, washing out the alkali, and 

 finally determining the cobalt as CoS0 4 by evaporation with sulphuric acid. 

 In these latter cases the nickel was determined in the nitrate from the double 

 nitrite of potassium and cobalt by precipitation with potash. 



The water and sulphuric acid were determined in the usual manner. The 

 potash was determined by difference in most cases, but was occasionally 

 checked by determining it as potassium sulphate. 



Fig. 1 . — Scries A. 



The Roman numbers indicate the different fractions of the conjugated salts. The co- 

 ordinate numbers show the percentage of NiO, and the abscissas numbers the percentage 

 of CoO in the several fractions. 



