110 DR BREWSTER on Hopeite, a New Mineral, 



Hence the specific character of the mineral, in relation to its 

 form, will be 



Prismatic, P = 139 41' ; 107 2' ; 86 49' 

 Pr = 101 24' (Pr + oo ) 3 - 81 34' 



w 



Cleavage, Pr + co perfect, eminent. Pr + oo imperfect. 



Chemical Character. It is entirely soluble without any resi- 

 due, and without swelling or effervescence, in the muriatic and 

 the nitric acids ; but more rapidly in the former than in the lat- 

 ter. It is acted upon very slowly by sulphuric acid, whether 

 strong or diluted ; but is finally dissolved by it. 



When exposed to the blowpipe * alone in the matras, it gives 

 off a great quantity of water, without any trace of carbonic acid. 

 It becomes first milk-white, and melts afterwards very readily 

 into a clear colourless globule, which, in melting, gives the flame 

 a greenish tint. With salt of phosphorus it melts in all propor- 

 tions very readily into a clear colourless glass, no skeleton of si- 

 lica being observed. If the mineral is in great proportion to the 

 salt of phosphorus, it turns opaque in cooling, but no fumes of 

 zinc are condensed on the charcoal f. With borax it fuses into 

 a clear colourless glass, which does not turn opaque in cooling. 

 It gives with soda a scoria, which, when hot, is of a yellowish co- 

 lour. The oxide of zinc is condensed round it in great quantity 

 upon the charcoal, and nearest to the scoria is a reddish-yellow 

 tint, which does not vanish in cooling, and indicates the presence 

 of Cadmium. When melted with soda, and moistened, it exhales 

 no hepatic odour. A solution of cobalt communicates a fine 

 bluish tint to the melted fossil. 



* This examination of the mineral with the blowpipe was made for me by 

 M. NORDENSKJOLD, an able chemist from Abo, during his visit to Edinburgh. 



f- With all the siliceo-carbonates of zinc, when melted with salt of phosphorus, in 

 such a quantity that the glass turns opaque in cooling, a very perceptible ring of 

 oxide of zinc is condensed on the charcoal. 



