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PROPERTIES OF PLATINA.
PROPERTIES OF PLATINA. i
Platina purified from all extraneous mixture is of a white co-lour, intermediate between that of silver and tin. It is thehardest of all metals. Its specific gravity being from 20.6 to23, makes it by far the heaviest body known. It is hard, mal- ;
leable, ductile, laminable like gold; but to what degree is not !
yet ascertained. We have seen platina drawn into a wire of a i
smaller diameter than the two thousandth part of inch. It is i
the most infusible of all the metals. It cannot be melted (in a )
considerable quantity at least) by the most violent heat of our !
furnaces, but may be fused by the heat of a burning lens, or by j
the assitance of oxigen gas. When pure, its parts may be made -
to combine or weld, by hammering in a white heat; a property j
confined to this metal and iron. It suffers no alteration from theaction of air; neither water, the earths, nor the salino-terrene jsubstances have any power of re-action upon it. Potash acts upon jit at high temperature. It is not oxidated when exposed red- jhot to the air, for a very long time. It may however be oxi-dated by the galvano-electric spark, and by the nitro-muriaticacid. This acid dissolves it and assumes first a yellow and after- jwards a deep orange colour. The solution tinges animal sub- ;stances with a dark colour, and may be decomposed by alcalies andby muriate and nitrate of ammonia, which have no effect on so-lutions of gold. No other acid exercises any action upon it. Theoxid of platina which is a triple compound, consisting of ammo-nia, muriatic acid, and platina may be reduced by the actionof a violent heat. Platina combines with phosphorus and sul-phur with considerable facility. It unites with the greater num- •;ber of the metals by fusion. Of these alloys, that with copper is ;the most valuable, as it is ductile, susceptible of a fine polish, <and does not tarnish on exposure to air; the rest of them are verylittle known, if is therefore unnecessary to dwell on them parti- i«ularly.