DR T. THOMSON on the Composition of Blende. 339 



a slight tinge of yellow. It was tasteless and insoluble in water, 

 and, when examined before the blowpipe, exhibited precisely 

 the characters of blende. When digested in muriatic acid, it 

 dissolved with effervescence, giving out abundance of sulphu- 

 retted hydrogen gas, and leaving a very small quantity of undis- 

 solved sulphur. Blende, when dissolved in muriatic acid, gave 

 out the same gas, and likewise left a very small quantity of sul- 

 phur undissolved. The weight of the sulphuret of zinc which I 

 had thus formed, was exactly 25 grains. 



Now, 21 grains of oxide of zinc are composed of, 



Zinc, ,^, , ; , . . . ,.;,.,.- 17 

 Oxygen, .,_.... 4 



a- ., /. . ,:-,;; : -; ;,;/V, : ...- ~ 



17 zinc are equivalent to 4 atoms, and 4 atoms sulphur weigh 8. 

 Thus it appears that the sulphuret of zinc formed artificially was 

 composed of 



Zinc, 17 or 4.25 



Sulphur, ..... 8 2 



25 6.25 

 il ' .ij ikf 1 .'J i:. : : vj*j ;;v:J> a : i :. : r, .''"'> i\.-(\'u 



This experiment corresponds exactly with those which I had 

 previously made to determine the atomic weight of zinc and of 

 sulphur, and serves to confirm them, if any confirmation had 

 been wanting. 



The very same sulphuret of zinc is obtained when oxide of 

 zinc and flowers of sulphur are heated together in a green glass 

 retort. 



I made many attempts to form a super-sulphuret of zinc, by 

 heating sulphur and oxide of zinc in various proportions, and at 



VOL. XI. PART II. U u 



