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III. Plasma with Nitre.

Nitre, which reduces all the known metallic bodies,except gold, silver and quicksilver, into a calx, was mixedwith equal its weight of platina, the mixture thrown intoa red hot crucible, and the fire kept up for about a quarterof an hour. No deflagration happened; and the platina,freed from the fait by repeated washing with water,appeared to have suffered no other change than having itscolour darkened, an effect which the simple heat wouldhave produced in it. The nitre was nevertheless in greatpart alcalized.

Four ounces of platina and eight ounces of the purestnitre were put into a crucible, the crucible covered with alarger one inverted over it, and kept in strong cementation,in a wind furnace, for three days and three nights withoutintermission. The matter being now boiled in water toseparate the salt, the platina looked rusty coloured, and hadlost almost half its weight: the saline liquor, on beingfiltered, left a brownish powder somewhat more thanequivalent to this diminution, and being afterwards eva-porated to dryness, yielded a small quantity of a greenishcaustic alcali. The fame platina was cemented thricemore with the fame quantities of fresh nitre, and the firecontinued for three days and three nights every time. Inthe two first repetitions, a smaller quantity of a palerpowder separated, and the remaining metal in good mea-sure lost the rusty hue which it had contracted before.After the last cementation, the little quantity of metalwhich remained had much the same appearance as the pla-tina at first: on washing it, there was scarcely any furtherseparation of powdery matter, but the nitre was still alca-lized. The platina was then mixed with sal ammoniac,and the fait sublimed in a Florence flask: the salt arose

S s f uncoloured,