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some its own whiteness, as to copper* and producing withothers a new colour, as with bismuth* lead* and gold;that it preserves copper and iron from tarnishing or rustingin the air, but occalions lead and bismuth to tarnish in aremarkable manner.

2. Though platina, when its quantity is not very large,becomes fluid with most of the metals in a moderate fire,a strong one seems to be always requisite for its perfectand total solution. Compositions of copper, of silver, andof lead, with one third their weight of platina, which hadflowed thin enough to run freely into the mould, and ap-peared to the eye perfectly mixed; on being digested inaquafortis till the menstruum ceased to act, left severalsmall grains of platina in their original form. Uponviewing these with a microscope, some appeared to havesuffered no alteration: others (hewed a multitude of small,,bright, globular protuberances, as if they had just begunto melt.

3. Mixtures of copper, silver, and lead with smaller,proportions of platina, which had been kept in strongfusion for some hours that the platina might be wholly in-corporated, were digested and boiled in fresh portions ofaquafortis, till the platina was left by itself in sine powder,,free from any tiling that aquafortis could extract. These-powders were exposed to very vehement sires, without ad-dition, with the addition of borax, with alcaline salts, andwith flint glass: they proved as unfusible as the platinaat first, neither melting, nor communicating any colourto the salts or glass. It appears therefore that the platinais only simply dissolved by the metals in fusion, and doesnot by their means become truly fusible, itself.

4. As platina unites with several metals into compoundsof new qualities, such as the ingredients neither possessfcparately, nor cam be conceived, on any known mecha-nical