1 676 3 
PAPER IV. 
Platina mixed with Semi-metals. 
1 . With Mercury. 
Read July 4, j. A N ounce of platina and fix ounces 
‘754- il c f p Ure quickfilver were rubbed 
together, with a little common fait and water, and 
a few drops of fpirit of fait, in an iron mortar. Af- 
ter fome hours trituration, the grains of platina be- 
came coated with the quickfilver, fo as to cohere in- 
to an imperfect amalgam. A part of the fluid quick- 
filver, poured off, and evaporated in an iron ladle, 
left a confiderable quantity of a dark-coloured pow- 
der, intermingled with bright fhining moleculae : A 
part ftrained through leather, left a fmaller propor- 
tion of a fimilar. powder. 
The platina, which had been thus attenuated by 
the mercury, fo as to pafs with it through the pores 
of leather, proved as refractory in the fire as at firft. 
Expofed to a very vehement heat, by itfelf, with bo- 
rax, with white glafs, it neither melted, or fuffered 
any fenfible alteration ; nor did it communicate any 
colour to either of the fluxes. 
2 . One part of platina and about four of lead 
were melted perfectly together ; and after the heat 
had fome what abated, poured gently into three times 
the quantity of quickfilver, heated fo as to fume. A 
blackifh powder was immediately thrown to the fur- 
face : This appeared to be chiefly platina. On grind- 
ing them together, a frefh powder gradually fepa- 
rated j which, being occafionally wafhed off, in ap- 
pearance 
