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Mr. SchefFer proceeded in a different manner. Theplatina was first strongly heated in a crucible by itself, anda little arsenic being then thrown upon it, they immedi-ately melted together. He observes, that platina meltswith arsenic as easily as copper and iron do when they areblended with arsenic; that there is no occasion for anyflux; that one part of white arsenic is sufficient for fourand twenty parts of the platina; and that the platina thusmelted with arsenic is quite brittle, and breaks grey likearsenicated silver.

On repeating this experiment it appeared, that thoughthe judicious author is by no means chargeable with anymistake, yet the little quantity of platina, he had to allowfor the trial, made it impossible for him to discover thelimitations, with which this strong action of arsenic onplatina ought to be understood. When only a few grainsof platina are used, there is all the appearance of truefusion, but on taking larger quantities we frequently findthe fusion to be only superficial and imperfect. An ounceof platina was strongly heated in a crucible, and pieces ofwhite arsenic repeatedly thrown upon it, the arsenicamounting in all to near as much as the platina; some ofthe grains melted into round drops: the greater part co-hered into a mass, differing from those, into which platinaitself is formed by fire, in the surface being smooth anduniform, and the grains in the internal part more firmlycoherent. I treated another ounce of platina in the famemanner, and with the fame event: the mass was of asmooth surface, as if it had been perfectly melted, but itsinternal part was composed of grains of platina in theirusual form. I put both masses into a crucible, with fresharsenic mixed with powdered charcoal, and urged themwith a strong fire for half an hour: they run into onelump, of the figure oif the bottom of the crucible, exter-

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