73 



as the fracture readily shows. We shall now consider the 

 present specimens chemically, with the assistance of Mr. 

 Chenevix, who, as well as Count Bournon, remarks the 

 rarity of this substance in any other country j and it ap-; 

 pears that Mr. Haiiy had only seen the hexaedral va- 

 riety of arseniate of copper from Cornwall, in the hands of 

 a friend, when he was about his very ingenious work on 

 crystallography. We therefore may safely conclude that 

 the present and first species of Count Bournon, with all the 

 others, are described in the Philosophical Transactions only, 

 or in works copied from thence. We shall, however, ex- 

 hibit some varieties not yet , described, one of which may 

 be seen in the next plate. 



That able chemist Mr. Chenevix, having favoured the 

 public with the analysis, found it to contain 



Oxide of copper 49 



Arsenic acid 14 



Water 35 



98 



