340 M. Arfwedson on the Decomposition of [May, 



fused even when exposed to a higher temperature than was 

 necessary to fuse N l S. Thus the two sulphurets differ in several 

 respects from each other. 



Analysis of native Sulphuret of Nickel, or the Mineral called 



Hair Pyrites. 



Klaproth, who analyzed this mineral, found it to consist of 

 metallic nickel mixed with a little cobalt and arsenic ; and this 

 conclusion was considered as correct till Prof. Berzelius, a few 

 years ago, in consequence of a set of experiments on it by the 

 blowpipe, concluded that hair pyrites was not metallic nickel, 

 but sulphuret of nickel ; but as no analysis of it, so far as I know, 

 has yet been made, I conceived that the undertaking should not 

 be neglected, especially as Prof. Berzelius had the goodness to 

 present me for the purpose with a very beautiful piece of that 

 rare mineral. 



a. 0*222 gr. of needles of hair pyrites freed as much as possi- 

 ble from the small fragments of quartz with which they were 

 mixed, were digested in aqua regia, as long as any thing was 

 dissolved. The solution, together with a small portion of sul- 

 phur swimming upon the surface, was decanted off, the quartz 

 grains lying at the bottom of the flask. These grains, when 

 washed and heated to redness, weighed 0*006 gr. The undis- 

 solved sulphur was likewise separated. It weighed, after being 

 washed and dried, 0*002 gr. 



h. The solution in aqua regia was precipitated by muriate of 

 barytes, and the sulphate of barytes obtained being collected on 

 the filter and edulcorated, weighed, after being heated to red- 

 ness, 0*524 gr. containing 0-18 sulphuric acid, or 0*072 sulphur. 



c. The residual liquid was freed from barytes by sulphuric 

 acid, and then precipitated by caustic potash. The hydrate of 

 nickel containing potash was collected on a filter, and washed 

 with hot water, till the liquid which passed through ceased to 

 leave any residue when evaporated to dryness. It took several 

 days to accomplish this. Being then dried and heated to red- 

 ness, it was oxide of nickel, and weighed 0*176gr. equivalent to 

 0*139 gr. of metallic nickel. 



A portion of this oxide of nickel was dissolved in muriatic 

 acid, and the solution was supersaturated with caustic ammonia. 

 By this means the precipitate which appeared at first was dis- 

 solved, with the exception of a few inconsiderable flocks, which 

 being examined before the blowpipe were found to be alumina 

 mixed with oxide of iron. These flocks without doubt owe their 

 origin to the stony matter accompanying the hair pyrites. From 

 the ammoniacal solution the oxide of nickel was precipitated 

 by caustic potash. The residual liquid was colourless, but when 

 it was evaporated to dryness, and again redissolved in water, 

 there remained a brown powder, which gave a blue glass with 

 borax, and consequently was oxide of cobalt ; but the quantity 



