[ i6 4 ] 
made trial of, but without producing any fenlible 
effedt in either folution. 
4. The experiments with green vitriol were re- 
peated on the folutions of platina and gold made in 
fpirit of fait. The event was the fame as with thofe 
made in aqua-regis ; the gold being confbantly pre- 
cipitated, and the platina remaining diffolved. 
Remarks. 
It may be proper to obferve, that by the proceffes- 
here pointed out, the gold is purified from other 
metallic admixtures at the fame time that it is fepa- 
rated from platina ^ the inflammable fpirits reviving, 
effential oils and aether imbibing, and green vitriol 
precipitating, gold alone. Care fhould be had, that 
the piece of the mixt, taken for examination, be 
totally diffolved before any trials are made with the 
folution ; the menftruum not adting with equal fa- 
cility on the two metals, but diffolving the gold 
more readily than the platina. Where the acid has 
been dilute, and only a gentle heat applied, great 
part of the gold has appeared to be taken up before 
the platina was confiderably added on. Where the 
filter, with the gold in it, is burnt in the crucible, 
borax is the moft commodious flux : but as this fait 
gives a fenfible palenefs to gold, a little nitre may be 
injedted, after the metal has come into fufion, to 
reftore its colour. If the nitre was added at firff, 
whilft the gold continues fubtilely divided, fome par- 
ticles of the metal would be diflipated during the 
deflagration, which that fait produces with the coaly 
remains of the paper*. 
As 
