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of being a proof of its containing gold, affords rather apresumption of its being a ponderous body distinct fromg°.ld.

IV. Malleability of Platina.

Some of the purer grains of platina, by gentle strokes ofa flat hammer upon a smooth anvil, bore to be extendedinto thin plates, without breaking or cracking about theedges : some cracked before they had been much flattened,and discovered internally a close granulated texture : otherswere so brittle as to be reduced, without much difficulty,into powder. Even the tougher ones soon broke from rudeblows in-an iron mortar ; and they seemed all to be morebrittle when red hot than when cold.

Mr. Scheifer, in his little quantity of platina, did nottake notice that the grains differed in toughness : the par-ticles he tried having been of the more malleable kind, hemakes platina in general to be as malleable, a metal as thebest iron. Mr. Macquer seems also to have tried only asingle grain : he says he took one of the largest of thegrains, and having beaten it with moderate strokes on asteel anvil, he found that it suffered itself to be flattenedinto a pretty thin plate, which however cracked upon con-tinuing the beating. But Mr. Marggraf examined severalgrains, and observed the same difference in their malleabi-lity as I. had done : some stretched considerably ; othersbut a little, breaking from a few blows ; whilst others boreto be extended into pretty thin plates : he takes notice thatthese last were mostly the convex grains.

Upon the whole, as many of the grains are apparently ofconsiderable malleability, and as the blittleness of theothers proceeds doubtless from some. accidental cause, wecan by no means refuse platina the title of a malleable me-tal ; though little advantage can result from this property,unless means should be found of uniting the grains intolarger- masses. V. Platina