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mena which did not occur to me. They were all per-formed in small glass retorts, with receivers adapted tothem ; and the fire gradually raised, so as to make the re-torts red hot. In this manner he treated platina witheight times its weight of each of the three foregoing acids;with twice its weight of mercury-fublimate ; with twiceits weight of sal ammoniac ; and with thrice its weight ofthe mixture called sal alembrot, composed of one partof mercury-fublimate and two of sal ammoniac. Thequantity of platina in each experiment was sixty grains.

With the nitrous and marine acids, he had a whitecrystalline sublimate in the neck of the retort, which,viewed through a magnifying glass, looked like crystallinearsenic, but whose quantity was too small to be submittedto any further examination. When the marine acid wasused, there was also another sublimate of a reddisli colour ;and in all cases, the remaining platina was changed in partto a reddish brown. Mercury-fublimate arose uncoloured,and left the platina of a dark greyisla colour, here and therereddish. The sal alembrot arose also perfectly white, butwas followed by a little yellowilh matter : the remainingplatina was of a bright whiteness, almost like silver. Withsal ammoniac there was a fine yellow sublimate (errone-ously called blue in the Berlin memoirs) like that whichrises from a mixture of this salt with iron ; the remainingplatina was rather whiter than at first, and after some timegrew a little moist in the air.

Mr. Marggraf expressly mentions his using in these ex-periments the crude unpicked mineral; whereas in mineonly the larger white grains were employed, from whichall the heterogeneous parts and ill coloured grains, thatcould be distinguished by a good magnifier, had been care-fully picked out. It is pretty certain, that the sublimatesdid not proceed from the platina itself, but from its ad-mixtures,