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Updated: June 20, 2025
Osmium from a volatile compound of same thus deposited makes a filament as good as carbon when in vacuo." In 1888, long before there arose the actual necessity of duplicating phonograph records so as to produce replicas in great numbers, Edison described in one of his caveats a method and process much similar to the one which was put into practice by him in later years.
Copper ore is dug from several mines in California, but it is all exported to be smelted elsewhere. Platinum. Platinum, iridium and osmium, three white metals of about the same specific gravity with gold, are found with the latter metal in the placers in the basin of the Klamath and Trinity Rivers.
In that state of combination, as shewn in the table, the iridium and osmium are found combined in crystals, sometimes to the amount of 0.5 per cent., and sometimes 3 or 4 per cent. Now, this Deville proposes to deal with in the dry way, in the place of dealing with it by any acid. I have here another kind of platinum; and I shew it to you for this reason.
Platinum, iridium, and osmium are obtained with the gold in some of the placer mines, but are never found alone, nor are they ever the main object sought by the miner. The annual yield of our gold mines is about forty millions of dollars, of our quicksilver two millions of dollars. Our silver, copper and coal mines have been opened within a year, and their value is yet unknown.
Then there is this curious relation, that palladium and iridium are very much alike, so that you would scarcely know one from the other, though one has only half the weight of the other, and only half the equivalent power. So with iridium and rhodium, and osmium and ruthenium, which are so closely allied that they make pairs, being separated each from its own group.
An equal volume of lead would have weighed about four hundred pounds, but this was decidedly more than four hundred pounds. Indeed, the combined strength of the three men did not do more than rock it. "Well it certainly is no kind of matter we know of!" observed Morey. "Osmium, the heaviest known metal, has a density of twenty-two and a half, which would weigh about 730 pounds.
These are platinum, gold, tungsten, mercury, lead, palladium, silver, bismuth, uranium, vanadium, copper, cadmium, cobalt, arsenic, nickel, iron, molybdenum, tin, zinc, antimony, tellurium, manganese, tatiaum, chromium, columbium, rhodium, iridium, osmium, cerium. Many of these, however, are so rare, that as yet they are of no practical use.
One side of the question has been specially studied on account of its great practical interest, that is to say, the fact that the relation of the luminous energy to the total amount radiated by a body varies with the nature of this last; and the knowledge of the conditions under which this relation becomes most considerable led to the discovery of incandescent lighting by gas in the Auer-Welsbach mantle, and to the substitution for the carbon thread in the electric light bulb of a filament of osmium or a small rod of magnesium, as in the Nernst lamp.
The following comparative table shows the approximate prices of various metals in December, 1874, and December, 1884: Gold now ranks highest in value of all metals, the competition of osmium and iridium having been over come. It is only by reason of improved methods of preparation that the latter have become cheaper, while their use has at the same time increased.
Then these metals are the most infusible that we possess. Osmium is the most difficult to fuse: indeed, I believe it never has been fused, while every other metal has.
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