48 Transactions. 
A piece of stout silver wire was ignited with this salt for one quarter of 
an hour, the fused mass allowed to cool, and then examined, when an abun- 
dance of chromate of silver was discovered to have been formed, while the 
wire had been greatly corroded and reduced to half its bulk. 
A second piece of silver wire was completely dissolved in a subsequent 
fusion with the chromate for an equal time. 
Gold (and platinum) treated in like manner refused to dissolve, at least 
to any perceptible extent. 
It is therefore certain that in bichromate of potash we have a means 
of separating silver from native gold, at least to some extent, but to what 
extent could not well be determined in the Laboratory. In any case, 
the method is well worth a trial by assayists and bank managers. 
The manner of application is simply to place the salt upon the surface 
of the molten metal. I should not consider it at all necessary to attempt their 
mechanical admixture, as the silver being taken up from the top, currents 
would be produced in the metallic mass, and kept up with gradually 
decreasing force until the whole of the silver was removed. Possibly an 
intermittent agitation of the saline portion might be found advantageous. __ 
To prevent loss of silver by volatilization, it is tosta that the 
bichromate should be free from chlorides. 
Besides the separation of silver from auriferous alloys, this method is 
equally effective in removing copper and iron when present. To insure, 
however, the continuous fluidity of the saline stratum, the applieation of 
borax might be continued, but nitrates or caustic alkalies must be rigorously 
excluded. 
The silver is easily recoverable, as the chromate, being soluble in water, 
may be dissolved therein, the silver precipitated by hydrochloric acid, and 
the resulting chloride of silver finally decomposed by soda. 
The quantity of bichromate theoretically required to oxidize the silver 
and form with it this salt, is 5 equivalents to every 3 equivalents of silver, 
or, weight for weight, one pound of silver would require two and thirty-four- 
hundredths of a pound of the bichromate ; but in practice the quantity re- 
quired would no doubt be more, as some of the oxygen would be liberated 
out of contact with the alloy. For this reason it would be best to add the 
salt in successive portions, and for the same reason it is probable that the 
process would be found more adapted to the separation of silver when pre- 
sent in proportionally small quantities. 
Allowing, however, an equal weight of the salt for loss of this kind, and 
taking its retail price at 1s. 6d. per pound,—as per Jackson and Townson’s 
Price List,—every pound of the silver would incur a cost, on this head, of 
7s. for its removal. 
