[ *54 ] 
remelted it feveral times with vehement degrees of 
lire, fuffering it to cool leifureiy in the crucible j 
and, in order to feparate as much as poffible of die 
lead, to which its fpongineis feemed owing, boiled 
it in aqua-fortis, and repeatedly injected corrolive 
fublimate upon it during fulion : the mafs, neverthe- 
lefs, ftill turned out cavernulous and brittle, and fpe- 
cifically lighter than either the gold or platina b} r 
themfelves. 
2. I likewife endeavoured to combine platina with 
fmall proportions of gold. By vehemence of lire, it 
was made to unite, tho’ not perfectly, with half its 
weight and lefs : but the mixtures were extremely 
fpongy and brittle ; in fpecific gravity one fcarce 1 6, 
another lefs than 1 5. 
3. As a call metalline body from the Spanifh 
Weft Indies, of which fome account will be given 
hereafter, appears to have been confounded with the 
mineral platina, this alfo was melted with an equal 
quantity of gold. They united with great eafe, by a 
moderate lire, into an uniform compound, tolerably 
compact, but whofe fpecific gravity was only i 6 {-; 
which is nearly the mean gravity of the two ingre- 
dients. 
Exp ERIME N T IV. 
As a fmall portion of copper fomewhat heightens 
the colour of pale gold, platina was melted with 
eight times its weight of ftandard gold made with 
copper alloy. The fufion was performed, as in the 
preceding experiments, in a clofe crucible, with a 
fkrong fire, but without any flux, and continued for 
about an hour. The metal appeared covered with a 
black 
