1824. J the Metallic Sulphates by Hydrogen Gas. 339 



here and there seemed to have undergone a commencement of 

 fusion. It was brittle, and easily reduced to a powder, which, 

 when rubbed against a hard body, gave a whitish-yellow metallic 

 streak ; and was attracted rather strongly by the magnet. It 

 dissolved in nitric acid, leaving a residue of sulphur. By con- 

 centrated muriatic acid, it was slowly attacked, with the evolu- 

 tion of sulphuretted hydrogen gas ; but in dilute muriatic acid it 

 did not seem to dissolve even when the action of the acid was 

 assisted by heat. 



The product of this experiment could not be an oxisulphuret, 

 because it is well known that the oxide of nickel is reduced to 

 the metallic state by hydrogen gas. I must have obtained a 

 sulphuret which contained less than two atoms of sulphur, as 

 the decomposition of the sulphate of nickel was attended with 

 the evolution of both sulphurous acid and sulphuretted hydrogen 

 gas. It is to be presumed that the salt lost one atom of sulphur, 

 so that the sulphuret of nickel obtained was a compound of one 

 atom of each of its elements. Let us see how this supposition 

 corresponds with the experiment. 1*015 gr. of sulphate of 

 nickel left a residue of 0*49 gr. This corresponds with 48-28 



from the hundred parts ; but the weight of N i S? : N i S : : 100 : 

 48*44. From this it is evident that the sulphuret obtained was 



Ni S. I ought to mention likewise that the reduction of the 

 sulphate of nickel should not take place in too high a tempera- 

 ture ; for in that case, the sulphuret of nickel melts into lumps, 

 in consequence of which an additional portion of sulphur is dissi- 

 pated, and the loss of weight turns out too high. 1 obtained in 

 an experiment made in this way from 1*095 sulphate of nickel a 

 residue of 0-513 ; yet according to the preceding calculation, it 

 ought to weigh 0.53. But I cannot with certainty affirm that 

 this additional loss of weight is owing merely to the escape of 

 sulphur; for at the time when the matter melts, if the gas which 

 escapes be set on fire, it burns with a distinct green flame. 

 From this it seems not unlikely that even some of the nickel flies 

 off as well as of the sulphur. 



1 now wished to know in what respects this lower combination 



of sulphur with nickel differed from Ni S-. A portion of this 

 second compound, therefore, was prepared by passing sulphuret- 

 ted hydrogen over red-hot oxide of nickel. 1*186 gr. ot nickel 

 oxide gave 1*438 gr. of sulphuret of nickel, which deviates very 



little from the quantity Ni S', which ought by calculation to 



have been obtained; for the weight of Ni : Ni S 2 :: 1*180 : 

 1*441. This combination of nickel and sulphur was pulverulent. 

 Its colour was a somewhat darker-grey than that ot the oxide. 

 It was not in the least attracted by the magnet. It could not be 



z2 



