C r 57 ] 
the ingot : where the proportion was fmall, the 
recovered gold was frequently, but not conftantly, 
found to be pure. 
From thefe experiments it appears, that mercury 
has a greater affinity with gold than platina, and that 
platina is capable of being totally feparated by elutri- 
ation ; but that the procefs is too vague and undeter- 
mined to be applicable in the way of affiay, as we 
have no mark of the precife time for difcontinuing 
it, and as we can never be certain, without making 
another allay, whether the whole of the platina is 
feparated or not. As a preparatory examination, 
where the quantities of platina and gold to be fepa- 
rated are large, it is neverthelefs of good ufe, as 
greateft part of the platina may by this means be 
walhed over with little trouble, and the gold brought 
into a lefs compafs, fo as to be commodioully fub- 
mitted to a perfect purification by the means here- 
after pointed out. This procefs has a fimilar effect 
on platina and gold to that of ftamping and walking 
on metallic ores ; which could not be reduced into 
pure metal in the furnace to'advantage, without the 
previous feparation of great part of the earthy and 
lfony matter by water. 
2. By Precipitation with Alkalies. 
Gold is precipitated totally by fixed alkaline fa Its, 
but platina only in part. When foliations of the two 
metals are mixed together, fo much of the platina 
remains fufpended, after faturation with the alkali, 
as to be readily diftinguilhable by the yellow colour, 
which it communicates to the liquor. It has been 
objected, 
