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colour appeared to have been only superficial, from an im-perfect mixture; most of the platina having been concealedin the internal part of the mass, and covered as it were witha golden coat. «

11. In some circumstances I have seen the gold, after ithad been thoroughly mixed with the platina, spued outagain in part to the surface. The foregoing bell-metalcoloured mixture, after repeated fusions with and withoutadditions, and in different degrees of heat, became onceyellow on the surface. On cupelling mixtures of platinaand gold with lead, I have oftener than once seen the re-maining button covered with a golden skin, and all theinternal part grey.

12. In melting the platina and gold together, a littleborax was always used as a flux ; with an addition of nitre,which somewhat heightens the colour of gold, or at leastprevents the borax from making it pale. Pieces of someof the mixtures were remelted, with borax alone, with ni-tre alone, with common salt, with fixt alcaline salt, andwith powdered charcoal : those with borax seemed to bethe palest, and those with charcoal powder the best co-loured, though the differences were very inconsiderable.

13. As a small portion of copper somewhat heightensthe colour of pale gold, I melted platina with eight timesits weight of standard gold made with copper alloy; thatis, three parts of platina with twenty-two parts of fine goldand two of copper. The fusion was performed, as in thepreceding experiments, with a strong fire, in a close cruci-ble, but without any flux, and continued about an hour.The metal appeared covered with a black scurf, and hadlost about a two-hundredth part of its weight. It wasmuch duller coloured, much harder under the hammer,and cracked sooner about the edges, than mixtures of finegold with considerably larger quantities of platina. By

repeated