OCR Text |
Show Platinum The mineral called platinum is really a natural alloy of platinum, iridium, rhodium, palladium, and often osmium, with varying amounts of iron, copper, and gold, according to the United States Geological Survey. It is usually usu-ally found as small nuggets, scales, and rounded or irrgular grains; its color is steel-gray. The specific gravity gravi-ty of the crude platinum varies from 14 to 19. The percentage of the metal varies also within wide limits, usually from 70 to 85 per cent. Platinum is almost wholly produced in California and Oregon, and output for the United States is practically limited to these States. Owing to its high melting point and great resistance to acids, platinum is extensively used for laboratory uten? ils. Platinum salts are employed in chemical chemi-cal analyses. In the manufacture of sulphuric acid the metal has been used in making large concentration kettles, but of late gold has been substituted for it. In photography, dentistry, and electric installation much platinum is used. Of late the manufacture of jewelry has consumed large quantities of it. It is extensively used for chains and for the setting of diamonds, the claim being made not only that it is more resistant than silver and harder than gold but that the stones are bet-ter bet-ter offset bv platinum and appear larger than in any other kind of setting. Owing to the high price demanded for platinum during the la t two years, a great demand for a substitute has arisen. At one time much platinum was used in the manufacture of incandescent incan-descent lamps, but it is now almost entirely replaced by tungsten. Platinum Plati-num triangles, used extensively in laboratories, have recently been successfully suc-cessfully replaced by similar appliances made of an alloy of nickel and chro- ! mium. Nevertheless there remains so many industrial applications of plati- J num for which no substitutes can be , found that it is not likely that the price will b much cheaper in the future. The present extensive UBe of platinum plati-num in the manufacture of jewelry is stated to be unfortunate, since other metals ca be substituted for it, and this fad is undoubtedly one of the principal causes of the great increase in the price of platinum |