of Nickel and its Oxides. 327 



According to this analysis protoxide of nickel has an atomic 

 weight of 4'669. This is lower than the number assigned 

 by Berzelius, and still lower than that which results from 

 the experiments of RothoiF's. But it is so much higher 

 than my number, 4*25, that I was desirous of discovering, 

 if possible, the cause of the difference between us. 



I dissolved 50 grains of crystals of sulphate of nickel, 

 purified by 5 successive crystallizations in water, and threw 

 down the sulphuric acid by chloride of barium, purified on 

 purpose. The sulphate of barytes, after thorough edul- 

 coration and ignition, weighed 42-41 grains = 14*62 grains 

 of sulphuric acid, or 29*24 per cent. 



Fifty grains of the same salt, being dissolved in water, 

 were mixed with a solution of caustic soda. The oxide of 

 nickel, after thorough edulcoration and ignition, weighed 

 13*79 grains, or 27*58 per cent. According to this analysis 

 sulphate of nickel is composed of 



Oxide of nickel, . . 27-58 or 4*716 

 Sulphuric acid, . . 29*24 or 5* 

 Water, 43*18 or 7*38 



100*00 

 This analysis was repeated with almost the same result. 



According to this analysis the atomic weight of nickel is 

 4*716, the very same as stated by Rothoff* to be the result 

 of his experiments. 



But a little consideration must satisfy us, that the oxide 

 of nickel obtained by this analysis is not the oxide which 

 exists in sulphate of nickel. For the water in the salt 

 (if the oxide weighs 4*716) is only 43*18 grains. But I 

 actually separated from it (as has been already stated) 

 45*54 grains of water, which is more than could have 

 existed if the atom of protoxide of nickel were 4*716, or 

 even 4*69675 as Berzelius makes it. 



For the component parts of this salt would be 



Oxide of nickel, . . 27*58 

 Sulphuric acid, . . 29*24 

 Water, 45-54 



102*36 

 giving a surplus of 2*36 per cent., which must be owing to 



