[ 52 ° ]

■which passage, when the luting was thoroughly dried, anounce of platina was placed. The crucible was coveredand set in a wind furnace, and a pretty strong fire kept upfor six hours. Being then taken out, some flowers of zincwere found adhering to the cover, greatest part of the pla-tina was melted into small bright globules, and suchgrains, as retained their figure, appeared frosted over withminute globular protuberances, as if they had just begunto melt. Its weight was increased above a third part, sothat it had imbibed about as much of the zinc as copperdoes in the common process of making brass.

Finding the fumes of zinc to act so powerfully on pla-tina, I next tried zinc in its common metallic form. Up-on an ounce of platina, covered with borax, and heated ina blast furnace to a strong white heat, I threw an equalquantity of zinc. A violent deflagration arose, and theplatina seemed to be almost instantly dissolved. The me-tal, being immediately poured out, run freely into themould, and was found to have lost near half an ounce inweight; so that the quantity of zinc, which had sufficed tokeep the platina in good fusion, was very little more thanone half of the platina.

I made several further trials of the fame kind, with dif-ferent proportions of the two metals, both in a quick firein a blast furnace, and in one more gradually raised in awind furnace : the zinc always proved a strong menstruumfor the platina, though much of the zinc was dissipated bythe heat requisite for rendering the mixture sufficientlyfluid. One ounce of platina and four ounces of zinc be-ing melted together in the blast furnace, as in the above ex-periment, the loss was an ounce and a half, so that thereremained with the platina about two ounces of the zinc.This compound was dropt upon another ounce of pla-tina, strongly heated as before with borax : the metal,

poured