131 



TAB. CLXVIII. 



CUPRUM arseniatum. 

 Arseniate of Copper. 



Class 3. Metals. Order 1. Homogeneous. 

 Gen. 10. Copper. Spec. 8. Arseniate of. 



Div. 1. Crystallized. 

 Syn. Arseniate of Copper. Bourn. Phil. Trans. 1801. 



1 his is the third variety of Arseniate of Copper, which the 

 Count de Bournon calls the acute octaedron, in which the 

 more inclined planes meet at an angle of 84°, and the others 

 at an angle of 68°. The first variety or obtuse octaedron is 

 figured in tab. 31. and 32., and the second variety in 

 hexaedral plates tab. 37. The present is mostly of a darker 

 colour than the others, and is commonly of a bottle-green 

 as it is called, viz. a dark blackish green. Like many 

 other crystallizations it is somewhat rounding, but mostly 

 with concave faces, which are here noticed in the geome- 

 trical figure as well as the straighter one, and also the 

 manner of the elongation of the octaedron towards form- 

 ing a prism, which it often assumes by being placed on 

 one end ; thus at first sight giving a new idea, and form- 

 ing a four-sided prism with a diedral summit. 



By the analysis of Mr. Chenevix, this species is found to 

 contain, 



Oxide of Copper ... 60 

 Arsenic Acid .... 39*7 



99*7 



