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io. Mr.Macquer put an ounce of platina into a Germancrucible, and exposed it to a strong sire for fifty hours, ina furnace whose heat,when continued for such a time, wascapable of melting the mixtures which Mr. Pott fays, iphis lithogeognojia, yielded him glasses the most hard and theleast fusible. On examining the platina after this trial,he found that it had not melted, and that the grains onlystuck together so as to form one mass, which had exactlythe figure of the bottom of the crucible, and which hadshrunk from the vessel so as to come freely out; that allthe surface of the mass .was tarnished and blackened, andchanged to a slate colour, with a diminution of the metal-lic brilliancy; that the internal part of the crucible, wherethe platina had touched it, was tinged as - if filings of ironhad been calcined in it; and that on weighing the platinaafter the operation, it was found increased fourteen grains,which amount (the French ounce consisting of five hun-dred and seventy-fix grains) to about one part in forty-one.The fame platina, submitted to another operation similarto the foregoing, received a further increase of two grains,the augmentation in all being sixteen grains, or one part inthirty-fix. There could be no suspicion, he says, of anycoals or ashes falling in, because the crucible was in a partof the furnace where such matters could have no access,and because it was also closely covered, though not luted.As the increase was inconsiderable in the second operation,he judges there would have been little or none on a thirdrepetition. We may add, that since after fifty hours strongfire, a further continuance of heat occasioned still a verysensible augmentation of weight, the difference betweenthe result of this experiment and Mr.Marggrafs, in regardto the quantity of the augmentation, may be easily account-ed for, from the different lengths of time that the fireswere continued,

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