162 MiscellaueoKs hiteUigence. 



arsenic acid by dissolving the salt in water, and causing a cur- 

 rent of sulphuretted hydrogen gas to pass through it, as long 

 as any precipitate appeared. By this method I threw down a 

 great deal of arsenic, but on filtering and evaporating the liquor, 

 it was still converted into an apple-green matter, and, of 

 course, contained arsenic. I found that when the salt was dis- 

 solved in water, the liquid became opaque, owing to a quantity 

 of arsenious acid, which separated from the salt. The liquid 

 being now filtered, to get rid of the arsenious acid, and pro- 

 perly evaporated, yielded a new crop of crystals of sulphate of 

 nickel. These crystals continued to be deposited as long as a 

 single drop of the liquid remained unevaporated. By this me- 

 thod may' the whole of the nickel in the speiss be obtained in the 

 state of sulphate of nickel. This sulphate is quite free from 

 arsenic or arsenious acids, for the presence of these acids pre- 

 vents sulphate of nickel from crystallizing. But for greater se- 

 curity I dissolve the sulphate of nickel in water, and crystal- 

 lize a second time. 



The pure sulphate of nickel thus obtained, is dissolved in 

 water, and decomposed by carbonate of soda. The carbonate 

 of nickel, when well washed and dried, is a light-green powder. 

 I make it up into balls with a little oil, enclose these balls in 

 a charcoal crucible, which is put into a Hessian crucible, the 

 mouth of which is covered and luted. It is now exposed to 

 the greatest heat that I can raise, in a melting furnace for two 

 hours. By this process I have always obtained a button of 

 pure nickel in the metallic state. 



The nickel thus obtained is hard, but malleable, and very 

 obedient to the magnet. I think it contains a certain propor- 

 tion of carbon in combination with the nickel. The button is 

 usually surrounded with a thin dark shining cuticle, which I 

 take to })& a carburet of nickel. — Annals of Philosophy. 



6. Analyses of Coal. — Dr. Thomson, has lately analysed the 

 varieties of pit-coal, with very extraordinary results. — The 

 species examined were, 1. caking coal, or Newcastle coal; 2. 

 splint coal, or light burn hard coal, being the fifth of the six 



