A new metal, to which that name was given by its discoverer, Mr. Tennant, from the striking variety of colours it affords whilst dissolving in muriatic acid. On examining the black powder left after dissolving platina, Mr. Tennant found it to contain two distinct metals never before noticed, which he named iridium and osmium. Lead unites with iridium easily, but separates by cupellation, leaving the iridium in the cupel as a coarse black powder. Copper forms with it a very malleable alloy, which, after cupellation, with the addition of lead, leaves a small proportion of the iridium, but much less than in the preceding instance. Silver forms with it a perfectly malleable compound, the surface of which is tarnished merely by cupellation: yet the iridium appears to be diffused through it in fine powder only. Gold remains malleable and little altered in colour, though alloyed with a considerable proportion; nor is it separable either by cupellation or quartation. If the gold or silver be dissolved, the iridium is left as a black powder.