„^g Mr . Keiu’s Experiments and Obfervations on 
6 Some years ago, I communicated to an artift the method ot 
cffe( W the reparation of filver and copper by means of the 
above-mentioned compound of vitriolic acid and nitre ; and, as 
1 am informed, that it is now commonly prattled by the ma- 
nufacturers in Birmingham, I have no doubt but it is muc 
more economical, and it is certainly much more eaiily executed 
than any of the other methods : for nothing more is required 
than to put the pieces of plated metal into an eait ien g ax 
pan ; to pour upon them feme of the acid liquor which may 
be in the proportion of eight or ten pounds of oil of vituol 
one pound of nitre; to ftir them about, that the furfaces may- 
be frequently expofed to frefh liquor, and to a i tit a ion y 
a gentle heat from 100* to 200“ of Fahrenheit s leal . 
When the liquor is nearly faturated, the ulver is to e P re ^|' 
tated from it bv common fait, which forms a Iona cornea, eaf ny 
by /citing it in a crucible with a fuffleieut qnantny 
of pof-alh ; and, laftly, by refining the me ted filver, if - 
cellfry, with a little nitre thrown upon it. In tins ma.rae 
filver will be obtained diffidently pure, and the copper w 
remain unchanged. Otherwife, the filver may be pt.c'p.tat. 
in its metallic ftate, by adding to the folution of 
of the pieces of copper, and a fufficient quantity o 
enable the liquor to ad upon the copper. . . . 
The property which this acid mature poffefles of diffolvtng 
filver with great facility, and in confiderable quantity, w, 
probably render it an ufeful menftruum in the leparatton 
filver from other metals, and as the alchemifts have diftin- 
gnilhed the peculiar folvent of gold under the title of J 
Li, a name fufficien.ly diftina.ve, though founded on » 
fanciful allufion t fo, if they had been acquainted with th ^ 
