158 Dr Thomson on the atomic 'weight of Nickel. 



weight was exactly 15.75 grains. The salt thus rendered an- 

 hydrous had an orange colour while hot, but became yellow 

 on cooling. To see whether it had lost any acid, water was 

 poured upon it. For some time no appearance of solution 

 was perceptible ; but after being digested on the sand-bath 

 for twenty-four hours, a complete solution was obtained ; thus 

 showing that the salt still retained the whole of its acid. 34.25 

 grains of sulphate of nickel then contain 15.75 grains of wa- 

 ter. 



3d, 34.25 grains of the same crystals were dissolved in water, 

 and mixed with a sufficient quantity of carbonate of soda to 

 throw down the oxide of nickel. The oxide thus obtained 

 was edulcorated, dried, and ignited. It had a dirty olive-green 

 colour, and weighed 8.44 grains. It was quite insoluble in 

 ammonia ; but dissolved with facility in aqua regia. 



Thus the constituents of 34.25 grains of sulphate of nickel 

 were found to be, 



Sulphuric acid, - 10. 



Protoxide of nickel, - . 8.44 



Water, - 15.75 



34.19 

 Loss, - - 0.06 



34.25 



The salt being neutral, and 10 being equivalent to 2 atoms of 

 sulphuric acid, let us divide by 2, in order to see the atomic 

 weight of protoxide of nickel deduced from this analysis. We 

 have for the composition of the salt, 



1 Atom sulphuric acid, - - 5. 



1 Atom protoxide of nickel, - 4.22 



7 Atoms water, - - - 7.875 



7.095 

 Loss, - - - 0.03 



The atomic weight of protoxide of nickel conies out 4.22. 

 But there is a loss in the analysis amounting to 0.03 grain. 



