SEP. OF COfPHR FKOM SILVER; J^.^ 



to promote the a6lion of the acid, it is of ufe to put one part 

 more to every fixteen parts of the alloy. Tiie matrafs is then 

 to be placed in a fand-heat, and the acid brought to a ftate of 

 ebulhtion. In two or three hours time the alloy is commonly dif- 

 united and converted into fulphate, particularjy if care betaken to 

 ftir the mafs from time to time with a glafs fpatula. This raafs 

 is thick, and frequently hard. While it is ftill hot, fix or eight 

 times its weight of boiling water is to be added to it, and it is 

 to be left fome time longer on the fire. The fulphate of copper 

 will be diffolved, and great part of the fulphale of fiiver will be 

 precipitated. The operator will now examine whether the 

 whole be completely diHTolved ; and if it be, a plate of copper, 

 or fome pieces of copper or halfpence tied up loofely in apiece 

 of coarfe linen, mnil be fufpended in the mixture, and the 

 whole kept boiling for fome hours. The fulphate of filver 

 will thus be decompofed, and the iilver feparated in the me- 

 tallic ftate. 



To afcertain whether the feparation be complete, a few Mode of afcer- 

 drops of folution of muriate of foda are to be dropped into a ^^^^'j'S '*'^^^^J . 



, . . ^'^^ ieparat;on DC 



little of the liquor. If a cheefelike precipitate be formed, it complete. 



is a proof, that all the filver is not feparated, and in this cafe 



the ebullition with the copper muft be continued longer. After 



the whole of the filver is feparated, tiie liquor is to be poured 



off, the precipitated filver is to be well wathed, and the entire 



reparation of the cuprous fait is to be afcertalned by the addition 



of 9 fevy drops of liquid ammonia to the water wTth which the ' 



precipitate has been wartied, which, if it contain any copper, 



will be rendered blue by the ammonia. After the filver is May b^keptia 



thoroughly freed from the fulphate of copper, it may be keot'^^^t'^f ' ?' ^''^'^'■^ 

 • .1 /^ r 1 •. • • , r /• , . . r' wjth fulphate of 



m the Itate ot powder as it is, or it may be fuled with a fourth potaA. 



or at molt half its weight of fulphate of potaHi.' 



The water poured off is then to be mixed with what was Blue vitriol ob- 



ufed for wafhing the precipitate, and evaporated in a coooer ^f "^'^ ^*^''^' ^"^ 

 r . r • . r , I . r . ^ *^t^ the colt of the 



pan, Jo as to obtain the lulphate ot copper by crvuallization. acid. 



The blue vitriol thus produced will be at leafl equal in value to 



the fulphuric acid employed. 



If any parts of the alloy remained undiffolved, tt ihould Undiflolved alloy 



be feparated by decantalion, and referved for a future ^'^ ^^^'^'''*' 



operation* 



SCJESTIFJC 



