He may get it as high as 78 per cent. of
platinum, and 22 of lead; or 5, or 10, or 15 of platinum, and 95, or 90,
or 85 of lead (which he calls weak platinum), and he then places it in the
kind of vessel that you see before you. Suppose we had the mixture here;
we should have to make it hot, and then throw in air upon the surface. The
combustible metal--that is, the lead--and the part that will oxidise, are
thoroughly oxidised; the litharge would flow out in a fused state into a
vessel placed to receive it, and the platinum remains behind.
[Illustration: Fig. 36.]
Here is the process which Deville adopts for the purpose of casting off
the lead, after he has got out the platinum from the ore. (Having made use
of your friend, you get rid of him as quickly as you can.) He gets his
heat by applying the combination of oxygen and hydrogen, or of carburetted
fuel, for the purpose of producing a fire. I have here a source of
coal-gas; there I have a source of hydrogen; and here I have a source of
oxygen. I have here also one of the blowpipes used by Deville in his
process for working platinum in the way I have spoken of. There are two
pipes, and one of them goes to the source of coal-gas, and the other to
the supply of oxygen.
[Illustration: Fig.
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