[ 5 2 4 1

more remarkable: Numerous metallic globules appearedall over the insides of the crucibles, and many on the co-vers also: the differences in regard to the fluxes, and in theproportions of the two metals, seemed to make no materialdifference in this respect. Some of the mixtures weremelted over again, in fresh crucibles, several times: themetal sparkled up in the same manner every time. Onpouring them into moulds, unless the heat was very in-tense, a considerable part remained behind, the silverseeming to quit the platina on an abatement of the heat.When the heat was so strong that the whole run fluid intothe mould, great part of the platina separated and fell tothe bottom in cooling, unless when the mould was verybroad, so that the compound begun to fix almost immedi-ately, without allowing time for the platina to subside.

6. I likewise melted silver with different proportions ofa precipitate of platina obtained by adding mercury to asolution of platina in aqua regia. Here also the event wasthe same: the metal sputtered up in extremely minutegrains, which seemed as it were to penetrate the crucible.

7. There appears upon the whole a strong repugnancebetween platina and silver. Mr. Scheffer takes notice alsoof the difficulty of uniting these two, though the sparklingup of the metal, which was not considerable in my ex-periments when the quantities were small, does not seem tohave been perceived at all in his. He observes that platinamelts more difficultly with silver than with lead or copper;that three parts of silver are necessary for making one partof platina melt by a blow pipe; and that the mixture re-tains the whiteness which both metals possess, but proveshard and brittle. In all my mixtures with large propor-tions of platina, the colour was greatly inferior to that ofsilver: besides being very dull, they had somewhat of ayellowish cast; and this yellowifhness continued sensible

even