338 DR T. THOMSON on the Composition of Blende. 



pound of 24 atoms sulphuret of zinc and 1 atom bisulphuret of 

 zinc, its constitution would agree very nearly with the analysis 

 of Mr T. MUIR. For 



24 atoms zinc 102 



1 atom zinc = 4.25 



Total zinc - 106.25 



24 atoms sulphur, ... 48 

 2 atoms sulphur, ... 4 



52 



Now, 



Zinc, . . 106.25 is the same as 67.15 

 Sulphur, .52 32.85 



158.25 100.00 



Such a composition would be analogous to what STROMEYER 

 has shewn to be the constitution of magnetic pyrites, which al- 

 ways contains an admixture of bisulphuret of iron. It was with 

 a view to ascertain how far zinc and sulphur are capable of en- 

 tering into various combinations, that the following experiments 

 were made. 



I mixed as intimately as possible 2 1 grains of pure oxide of 

 zinc with 20 grains of flowers of sulphur. This mixture was 

 put into a porcelain crucible, which, being covered with its lid, 

 was exposed over a spirit-lamp, to a heat at first very moderate, 

 but gradually increased till the crucible became red hot, and it 

 was kept at that temperature till the whole excess of sulphur 

 had been driven off. It was then allowed to cool. The matter 

 remaining in the crucible was a white pulverulent powder, having 



