iV. JV. Evans — Native Arsenic from Montreal. 93 



minute black reniform particles, which on account of their 

 extremely small size could not be accurately determined, but 

 which were some silicate of iron soluble in hydrochloric acid 

 and yielding gelatinous silica on evaporation. There were a 

 few little pockets filled with a soft black substance, moist, and 

 hardening on drying in the air. This seemed to be closely 

 allied in composition to the little particles mentioned above, 

 and on its free surfaces it exhibited a similar minute glossy 

 reniform structure. 



The arsenic itself is the variety known as "scherbenkobalt"; 

 it is in large masses, often several pounds in weight, formed of 

 concentric layers. It appears as though deposition, probably 

 due to some fumarole . action, had started at certain points on 

 the wall of the vein and layer after layer of the arsenic had 

 been added, producing a sort of onion-like lump of the material. 

 In time these masses grew into one another, giving a reniform 

 structure to the whole. Here and there on the surfaces of the 

 masses there are traces of crystalline structure, with angles 

 apparently of 90° ; but no faces were found well enough 

 developed to allow of any measurements being taken. The 

 mineral exhibits the usual characteristics of native arsenic ; the 

 mean of two analyses gave its composition as : 



Arsenic 98*14$ 



Antimony _ 1*65 



Sulphur 0-16 



Insoluble 0*15 



100-10 



^No silver, bismuth or other element was found, although care- 

 fully looked for. Two specimens gave for specific gravity 5*73 

 and 5*75 at 18°. The hardness is between 3 and 4. 



The deposit seems to be notable on account of the purity of 

 the arsenic, its large quantity, and the absence of associated 

 sulphides. 



Macdonald Chemical Laboratory, 

 McGill University, Montreal. 



