the Dijfohtwn of Metals in Acids % 
f , I 8 - DiIutIon with water rend ers this compound acid capable 
of diflolvmg copper and zinc, and probably thofe other metals 
w ic are fubjed to the adion of the dilute vitriolic or nitrous 
acids. 
SECTION SECOND. 
An account of a new procefs for feparating fiver from copper. 
19. The properties of this liquor, in diffolving filver eafily 
without a cl mg on copper, have rendered it capable of a very 
ufeful application in the arts. Among the manufadures at 
Birmingham, that of making veffels of filver plated on cop- 
per is a very confiderable one. In cutting out the rolled nlated 
metal into pieces of the required forms and lizes, there ar! 
many Ihreds, or /craps as they are called, unfit for any purpofe 
but the recovery of the metals by feparating them from each 
other. The eafieft and moft oeconotnical method of parting 
thefe two metals, fo as not to lofe either of them, is an object 
of fome confequence to the manufadurers. For this purpofe 
two modes were pradifed ; one, by melting the whole of the 
miired metals with -lead, and feparating them by eiiquation and 
telling ; and the fecond, by diffolving both metals in oil of 
vitriol, with the help of heat, and by feparating the vitriol of 
copper,^ by dillolving i|*in water, from the vitriol of filver, 
which is afterwards to be reduced and purified. In thefirff of 
thefe methods, there is a confiderable w-afte of lead and cop- 
per ; and in the fecond, the quan tity of vitriolic acid employed 
is very great, as much more is diffipated in the form of volatile 
mriohc, or fulphureousacid, than remains in the compofition of 
he two vitriols. 
5 
Some 
