[ *59 ] 
into a pretty thin plate before it cracked, and ap- 
peared internaily uniform and equal. This com- 
pound being diflolved in aqua- regia, and a fixed al- 
kaline fait added by degrees till the acid was more 
than faturated, the liquor became indeed pale ; but 
tin plates put into it quickly difcovered, that iit held 
a very confiderable quantity of platina. It appears 
therefore a conftant property of this mineral to re- 
main partially diflolved in the nentralifed liquor *, 
and that minute proportions of it, mixed with gold, 
are by this means diftinguifhable. 
4. Many other experiments were made of the 
precipitations and precipitates of gold and piatina, by 
alkalies both of the fixed and volatile kind. The moil 
remarkable effedts were, that volatile alkalies, added 
to both folutions in quantity juft fufficient to faturate 
the acid, precipitated gold intirely, but platina only 
in part, fo much of it remaining fufpended as to give 
the fame colour to the liquor as when fixed alkalies 
were made ufe of: that, on adding a larger quantity of 
the fpirit after the precipitation of the gold, the liquor 
became yellow, a part of the metal being taken up 
again ; and that the platina was more copioufiy re- 
diflolved, the liquor becoming of a deep brown ilh 
red : that the walked precipitates of both metals, 
whether made by volatile or fixed alkalies, proved 
foluble, by moderate digeftion, in fpirit of fait ; 
thofe of platina much more difficultly and fparingly 
than thofe of gold. 
3. By inflammable Liquors. 
1. Inflammable fpirits, which revive gold from its 
folutions in form of yellow films, have no fuch effect 
7 on 
