[ 6+3 ] 
of the figure of the bottom of the crucible, of a 
brighter colour than at firft. On a flight blow, they 
readily fell afunder again, and leem’d not to have al- 
ter’d their fhape. 
3. In feveral repetitions of the experiment, the 
platina began to cohere in a moderate white heat : 
the grains were at this time very ealily feparable, and 
feem’d to cohere the more flrongly in proportion as 
the heat was rais’d. In the moft intenfe fires, which 
the common velfels could not long fupport, the pla- 
tina did not melt, or foften, or alter its figure, or lofe, 
fenfibly, of its weight. The colour was conftantly 
brighten’d by a firong heat, and generally render’d 
dufky by a fmall one : on quenching it, when vio- 
lently heated, in cold water, the grains, which com- 
pos’d the internal part of the lump, acquir’d a violet or 
purple colour. 
Experiment y. 
1. As the power of fire upon metallic, as well as 
earthy fubftances, is remarkably promoted by the im- 
mediate contadt of fuel, and the impulfe of air upon 
the fubjedt \ platina was expos’d to its adtion in thofe 
circumftances. A crucible, having a bed of char- 
coal in it, was laid on its fide, in a good blaft-furnace, 
with its mouth towards the nofe of the bellows ; and 
four ounces of platina fpread upon the charcoal. 
The fire was vehemently urg’d for above an hour, 
during which an intenfe white flame pafs’d thro’ the 
crucible, and ifiii’d at an aperture made for that 
purpofe. The crucible was vitrify ’d : the grains of 
platina only fuperficially coher’d, and became brighter, 
as in the preceding experiment, without feeming to 
have foften’d or alter'd their drape. 
2. The 
