0; iridium, 1.2; rhodium, 0.5; palladium,
0.25; a little copper, and a little iron. It is, in fact, bad platinum: it
scales, and it has an unfitness for commercial use and in the laboratory,
which the other well-purified platinum has not. It wants working over
again.
Now, Deville's process depends upon three points,--upon intense heat,
blowpipe action, and the volatility of certain metals. We know that there
are plenty of metals that are volatile; but this, I think, is the first
time that it has been proposed to use the volatility of certain
metals--such as gold and palladium--for the purpose of driving them off
and leaving something else behind. He counts largely upon the volatility
of metals which we have not been in the habit of considering volatile, but
which we have rather looked upon as fixed; and I must endeavour to
illustrate these three points by a few experiments. Perhaps I can best
show you what is required in the process of heating platinum by using that
source of heat which we have here, and which seems to be almost
illimitable--namely, the voltaic battery; for it is only in consequence of
the heat that the voltaic battery affects the platinum. By applying the
two extremities of the battery to this piece of platinum-wire, you will
see what result we shall obtain.
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