1840.] 



Chemical Analysis of certain Minerals* 



40 



On selecting by means of the magnet, a few grains more magnetic 

 than the others, prussiate of potash, and tincture of galls, indicated the 

 presence of iron. Two small grains, picked out from the other grains, 

 proved to be silver. The mineral may possibly be menachanite, and 

 may contain titanic acid, but the quantity was too small to be subjected 

 to a sufficient examination. 



3. Malachite ? — (and a button of metallic copper). 



The proper tests gave distinctive indications, that copper was present 

 in this mineral. 



4. Silver ? — This specimen was a button or large globule ; it had a 

 blackish purple tarnish ; had been flattened by the hammer. On trying 

 its further ductility, it flattened under the hammer, and crumbled at the 

 edges ; the crumbled portion had a granular appearance ; globule cuts 

 like sliver ; white; on beating in the diamond mortar, it flattened and 

 was malleable. 



The usual tests left no doubt of its being silver : it dissolved in nitric 

 acid, and left only a little black powder as a residue. 



5. Gre^i silver ore ? — Crushes easily: frangible; powder not at all 

 the colour of the ore, but dark red lilac. The external characters of the 

 ore approach near to the description in Ure's Dictionary, of the grey 

 carbonate of silver and bi^mutliic silver. As the siJecimen was small, 

 a piece about the size of a pea was examined, and gave the following 

 indications : — 



Reduced to powder and treated with nitric acid ; slight disengagement 

 of nitrous gas : large | ortion undissolved. 



A. — This acid solution gave on testing the proper indications of silver. 



A. — This residue was treated with muriatic acid and heat : a part 

 was insoluble, B. — The muriatic solution was tested and gave the follow- 

 ing indications of antimony : — 



Wafer — The solution turned milky. 



Zinc — Black precipitate. 



Hydrosulphuret of ammonia — An orange coloured precipitate. 



B. — On this residue, muriatic acid and heat appeared to have no fur- 

 ther action. Nitric acid was then added, and the mixture boiled. 

 There was still an insoluble portion left. C— This nitro-muriatic solu- 

 tion was examined as follows 



