VOL. XII.] PHILOSOPHICAL TRANSACTIONS. 455 



is added of fine silver 1 or 2 penny-weights, called fixes, to every pound of aqua- 

 fortis, which in 4 hours will purge it from all dirt and impurity, and make it fit 

 for parting, which is thus done. If the silver gilt be fine enough for wire, they 

 only melt it in a wind-furnace, and cast it melted into a large tub of water, 

 that they may have it in small pieces; but if it be only standard, they first fine 

 it on the test. These small pieces taken out of the water, and well dried, are 

 put into a tapering glass, a foot high, and 7 inches at the bottom; then the 

 glasses are about -^ charged with aquafortis, and set in a range of iron, covered 

 2 inches deep with sand, with a gentle charcoal fire under it. Small bubbles 

 will soon rise, and the water also nui over. If so, they take oflF the glasses till 

 they cease boiling, or else pour some of it into a vessel. If lead be mixed with 

 it they cannot keep it from running over. When the water has once ceased 

 from this ebullition, it will rise no more. The greenness of the water shows 

 the quantity of copper contained in it. If the water boil over, it will penetrate 

 the bricks and wood. They commonly let it stand a night on the iron range, 

 with a gentle heat under it, and in the morning gently pour off the water im- 

 pregnated with all the silver, the gold lying like black dirt at the bottom, which 

 being washed out is put into small parting glasses, and set over the sand with 

 fair conduit-water for an hour, and then the water poured off. This is repeated 

 5 or 6 times, to separate the salt from the gold, which is now fit to be melted, 

 and cast into an ingot. 



To regain the silver, they have large round washing-bowls, lined within with 

 melted rosin and pitch, for otherwise the water would heat the wood and pene- 

 trate the sides of the bowl, covered with copper plates 10 inches long, 6 wide, 

 and half or more thick. Into these bowls they pour plenty of water, the more 

 the better the verditer, and then the silver- water; which working on the softer 

 metal of copper leaves all the silver in very fine sand, at the bottom and sides 

 of the bowl, and on the plates of copper ; which being taken out is washed, 

 dried, and melted for any use. Concerning the plates it is observable, that if 

 any brass or shruff metal be in them, they gather very little of the silver, the 

 latter mixing with it. 



Verditer is made from the copper-water poured off from the silver and whit- 

 ing, in this manner: they put into a tub 100 pound weight of whiting, on which 

 they pour the copper-water, and stir them together every day for some hours 

 together. When the water grows pale, they take it out and set it by for fur- 

 ther use, and pour on more of the green-water, and so continue till the verditer 

 be made. Which being taken out, is laid on large pieces of chalk in the sun, 

 till it be dry for the market. The water taken from the verditer is put into a 

 copper, and boiled till it comes to the thickness of water-gruel, now principally 



