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platina, and which do not belong to any known substancebesides. This debasement of gold per extraclum smiridhHispanici is mentioned by Lecher in his minera arenaria.,and several times hinted at in his phyjica subterranea.Both Lecher and Stahl indeed call the substance, whichthe gold receives from the emery, an earth, whereas platinais undoubtedly a metal; but this does not at all invalidateour supposition, for they give the name of earth also to thesubstance which copper receives from calamine in beingmade into brass, which is now known to be metallic.

From these observations I have been led to suspect thatthe European emerys likewise might possibly participateof platina. If this was certain, it would account satis-factorily for the use which some of the alchemists are saidto have made of emerys and other ferrugineous ores ; andwe should no longer doubt, or wonder, that by treatinggold with these kinds of minerals, they obtained a perma-nent augmentation; that this augmentation, though itresisted lead, antimony, aquafortis, and the regal cement,was separable, as Lecher owns it was, by quicksilver; andthat, when it exceeded certain limits, it rendered the goldpale and brittle.

If emery contains platina, I imagined it might he dis-coverable by boiling the powdered mineral in melted lead,and afterwards working off the lead upon a test or cupel.The experiment was made with eight ounces of the finestpowder of common emery, and the fame quantity of lead,which were covered with black flux to prevent the scari-fication of the lead, and urged with a strong fire for twoor three hours. The lead became hard, rigid, of a darkcolour, and a granulated texture, as if it had really im-bibed some platina from the emery; but in cupellation itworked almost entirely off, leaving only a bead about thesize of a small pins head, which was probably no other'.than silver contained in the lead.