DR T. THOMSON on the Composition of Bknde. 341 



though it gave out, at the same time, a perceptible smell of 

 sulphuretted hydrogen ; and paper, moistened with acetate of 

 lead, held over it, became brown. Muriate of barytes being 

 dropt into the solution, 2.089 grains of sulphate of barytes were 

 obtained, equivalent to 0.706 grain of sulphuric acid. 



The green -substance thus obtained was obviously an anhy- 

 drous hydro-sulphuret of zinc, composed of 1 atom oxide of 

 zinc, and 1 atom sulphuretted hydrogen. For 21 grains of oxide 

 of zinc being equivalent to 4 atoms, would require 4 atoms of 

 sulphuretted hydrogen, amounting to 8.5 grains ; for the atom 

 of sulphuretted hydrogen is 2.125. Thus, we have, 



4 atoms oxide of zinc, 21 



9 atoms sulphuretted hydrogen, . 8.5 



Total, . . . 29.5 



Now, the quantity which I obtained was 29.24 ; and I find by 

 the notes of the experiment, that a few flocks of the hydro-sul- 

 phuret were accidentally lost. Hence, if the whole had been 

 collected, it would have amounted very nearly to 29.5 grains. 



This hydro-sulphuret, when heated, gives out almost the 

 whole of its sulphuretted hydrogen, while blende may be ignited 

 in close vessels with very little change. A small portion of the 

 sulphur was acidified by the heat, and a little of the hydro-sul- 

 phuret was probably converted into sulphuret of zinc. 



The white flocks precipitated by the sulphuretted hydrogen, 

 constituted a hydrated hydro-sulphuret of zinc. 



Sulphuretted hydrogen gas does not form a sulphuret of 

 zinc at all, unless it be passed through hot oxide of zinc in a 

 tube ; and, in that case, nothing is obtained but common sul- 

 phuret of zinc. 



Being thus foiled in all my attempts to form a super-sulphu- 



u u2 



