that we obtain from nature, and work in our shops, are brought at last
into a mass by fusion. I am not aware that there is in the arts or
sciences any other than iron which is not so. Soft iron we do not bring
together by fusion, but by a process which is analogous to the one that
was followed in the case of platinum, namely, welding; for these divided
grains of spongy platinum having been well washed and sunk in water for
the purpose of excluding air, and pressed together, and heated, and
hammered, and pressed again, until they come into a pretty close, dense,
compact mass, did so cohere, that when the mass was put into the furnace
of charcoal, and raised to a high temperature, the particles, at first
infinitely divided for they were chemically divided adhered the one to
the other, each to all the rest, until they made that kind of substance
which you see here, which will bear rolling and expansion of every kind.
No other process than that has hitherto been adopted for the purpose of
obtaining this substance from the particles by solution, precipitation,
ignition, and welding. It certainly is a very fine thing to see that we
may so fully depend upon the properties of the various substances we have
to deal with; that we can, by carrying out our processes, obtain a
material like this, allowing of division and extension under a rolling
mill a material of the finest possible kind, the parts being held
together, not with interstices, not with porosity, but so continuous that
no fluids can pass between them; and, as Dr. Wollaston beautifully shewed,
a globule of platinum fused by the voltaic battery and the oxyhydrogen
blowpipe, when drawn into a wire, was not sounder or stronger than this
wire made by the curious coalescence of the particles by the sticking
power that they had at high temperatures. This is the process adopted by
Messrs. Johnson and Matthey, to whose great kindness I am indebted for
these ingots and for the valuable assistance I have received in the
illustrations.
The treatment, however, that I have to bring before you is of another
kind; and it is in the hope that we shall be able before long to have such
a thing as the manufacture of platinum of this kind, that I am encouraged
to come before you, and tell you how far Deville has gone in the matter,
and to give you illustrations of the principles on which he proceeds. I
think it is but fair that you should see an experiment shewing you the way
in which we get the adhesion of platinum. Probably you all know of the
welding of iron: you go into the smith s shop, and you see him put the
handle of a poker on to the stem, and by a little management and the
application of heat he makes them one. You have no doubt seen him put the
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