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weight 540 grains, so that it had lost above a twentiethpart more. It was further treated with half an ounce ofcalcined borax, the fame quantity of powdered whiteflints, and an ounce of fait of tartar: the mixture beingurged for two hours in a close crucible, with a vehementfire, the fcoriæ were of a topaz inclining somewhat to achrysolith colour; the metal of a fine white colour, spongy,rough on the surface, in weight 450 grains, so that it hadlost in this fusion one sixth part, and weighed now threeeighths less than the platina at first.

It may be presumed, that the metal obtained in this ex-periment was no other than a mixture of part of the pla-tina with some lead revived from the glass. Though theauthor took care, by covering and luting the crucible, toguard against the falling in of any inflammable matter thatmight revive the lead, yet such a matter might have hap-pened to be introduced in the pounding and sifting of theglass; and independently of any accident of this kind, therewas, perhaps, in the platina itself, a power sufficient forproducing the effect. Common platina, such as Marggrafemployed, plainly contains iron; and on barely stirringglass of lead in fusion with an iron rod, part of the lead isrevived. I mixed some of the purer grains of platina bothwith glass of lead and with glass of antimony, and exposedboth mixtures to a fire as strong as I could excite: the pla-tina strewed no disposition to melt, the grains remainingof their usual appearance. Vogel seems therefore to haveill understood Marggrafs experiments, when he con-cludes from them that platina yields a white regulus withglass of lead.

Mr. Marggraf gives also another experiment of thefusion of platina, with an arfenicated glass of lead. Aglass was prepared by melting together eight ounces ofminium, two of flints, and one of white arsenic. Six

ounces