ANALYSIS Of ORES OF SILVER.

157

a Prussian blue, which, after torrefaction, was magnetic.Hence he concluded, that these 5 parts were a combination ofiron and arsenic acid.*

Red silver ore was analyzed by Vauquelin in the followingmanner : One hundred parts of it were digested in 500 parts ofnitric acid previously diluted with water.f The undissolvedresiduum, being washed and dried, weighed 42.0 6. Beingtreated with muriatic acid, it was all dissolved except 14.06parts, which were sulphur. The. muriatic solution, when dilutedwith a great quantity of water, deposited a white powder, whichweighed 21.25, and w'as oxid of antimony. The nitric solutionremained still to be examined. Muriatic acid occasioned a heavyprecipitate, w'hich was muriate of silver. Reagents showed thatthe acid retained no other substance in solution. |

Muriate of silver w'as analyzed by Klaproth in the followingmanner : One hundred parts of it were mixed with thrice theirw r eight of pure carbonate of potash, and melted together in a glassretort. The mass was dissolved in water, and the solution fil-tered. A residuum remained, which was dissolved in nitricacid, with the exception of a red powder ; which, treated w r ithnitro-muriatic acid, was dissolved, except a little muriate of sil-ver, which, when reduced, yielded .5 of pure silver. Ammo-nia precipitated from the nitro-muriatic solution 2.5 parts ofoxid of iron. The nitric solution was precipitated by commonsalt; the muriate of silver, thus obtained, yielded, when reduced,6/»25 of pure silver.

The original aqueous solution of the alcaline mass was saturat-ed with acetous acid, on which it deposited 1./5 parts of alu-mine. The solution was evaporated to dryness, and the dry masstreated w r ith alcohol, which dissolved the acetite of potash. The

* Klaproth’s Beitrage i. 163

’ No effervescence occurred during the solution ; a proof that the metals existedin the ore in the state of oxids.

} ]oum. dr Min. No. xvii. p. 2.