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, -As the purest grains of crude platina have some ad-mixture of heterogeneous matter, it is possible that thismatter may prevent the intimate union of the platina andgold, and thus occasion the two metals, when blended to-gether, to occupy a larger volume than naturally belongsto them. I therefore melted gold with platina that hadpassed through some of the operations hereafter described,and which may be presumed to have been thereby purifiedfrom most of its heterogeneous parts.

One of the neatest beads of platina cupelled with lead,(article vi. No. 5, of the following section) Was meltedwith equal its weight of gold in a strong fire, and continuedin fusion about an hour: the mass proved spongy and verylight. I remelted it several times, with the most vehementfires I could excite; and in order to separate as much aspossible of the lead, to which its sponginess seemed owing,I beat it in pieces, and boiled it in aquafortis, and repeat-edly injected corrosive sublimate upon it during the fusion.The mass nevertheless still turned out cavernulous, andbrittle, and specifically lighter than either the gold or thebead of platina were by themselves.

Platina dissolved in aqua regia was precipitated by mer-cury, and the precipitate boiled in aquafortis and wellwashed with hot water. Twenty-six grains of this pre-paration were melted with four times as much gold: theplatina seeming to be imperfectly mixed, the fusion wasthree or four times repeated, and the quantity of gold in-creased to about eight times that of the platina. Thismixture proved as ponderous as the gold itself, or rathermore so: it weighed in air 16802, and in water 15934,whence its gravity was 19.357. ^ was examined by some

other gentlemen as well as myself, who all agreed in itsbeing remarkably heavy : Dr. Pemberton, with a veryexact balance, found the weight in air 229.735 grains, and

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