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V. Separation of Zinc from platina.

A mixture of platina and zinc, exposed hastily to astrong fire, deflagrated and appeared in violent agitation.This continued but a little time : the matter quickly be-came solid, and could no longer be made to flow, or thezinc, of which a considerable quantity still remained in it,to flame. The mass was very brittle, dull coloured, spongy,and, like the two foregoing, specifically lighter than thecrude platina.

VI. Cnpellation of platina with ILead.

1. A mixture of platina and lead was cupelled undera muffle in an assay furnace. For some time the processwent on well; the lead smoking moderately, and changinginto scoriae, which were thrown off to the fides and ab-sorbed by the cupel. In proportion as the lead workedoff, the matter required a stronger fire to keep it fluid ; andat length, collecting itself into a dull flat lump,, it couldno longer be made to flow in the greatest degree of heatwhich the furnace was capable of giving. The lump brokeeasily under the hammer, appeared of a dull grey colourboth internally and externally, and of a porous texture. Itweighed near one fifth part more than the quantity of pla-tina employed.

2. This experiment was many times repeated and va-ried. I endeavoured to scorify the lead in affay crucibles,by intense fires in a blast furnace; to work it off on bone-afli pressed into the bottoms of crucibles; and to blow itoff on tests before the nose of a bellows. The event wasstill the fame; the platina not only resisting the power oflead, which in these operations destroys or scorifies everyother known metallic body except gold and silver, butlikewise retaining, and preventing the scorification of, apart of the lead itself.