V 



DR T. THOMSON on the Composition of Blende. 343 



Zinc, 65.5 



Iron, ', ..). '.: . . . 1.372 

 Sulphur, ; . . . 32.628 



99.500 

 If we allow the loss to be zinc, we have 



66 zinc, requiring . . 31.0588 sulphur 

 1.372 iron, requiring . . 1.5394 sulphur 



Total, . . . 32.5982 



This exceeds the quantity of sulphur actually found by no more 

 than 0.03 grain, or less than icssth of the whole. 



Another variety of blende was subjected to analysis. It was 

 opaque, splendent, dark coloured, crystallized, and had a specific 

 gravity of 4.2434. Its constituents were found to be, 



Zinc, 64.33 



Lead, .... 5.215 



Iron, ... . . 1.33 



Sulphur, .... 32.915 



103.79 



64.33 zinc require of sulphur, . 30.27 



5.215 lead, 0.80 



1.33 iron, 1.52 



Total, .... 32.59 



The quantity of sulphur actually found exceeded this by 0.32 

 grains. 



I analyzed two other specimens of blende ; but the results 

 accord so nearly with those already given, that it seems super- 



