Platinum is associated with several other metals in the platinum sand which is found in some gold districts. They have not been j found as a distinct deposit in California; but have been observed in the United States Mint, in the operations ot assaying and parting. These associated metals are palladium, rhodium, iridium, and osmium ; to which we must add th(: lately discovered metal, ruthenium. The y have a sufficient resemblance to be classed together, and are obtained by a similar hydro m tallurgie treatment. The grains of iridosmin, found mixed with gold, have been qualitatively examined, and found to contain the new metal, ruthenium, as was observed by Claus in relation to the iridosmin from other localities. Palladium has been observed, and, at times, in sufficient quantity to render the gold brittle. The quantities of platinoid metals found in the California gold are small ; about one and a half pound of iridosmin having been obtained from about 25 tons of gold, 3-100000: but the greater part has, of course, passed into the coin, the coarser grains only being left.