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. You perceive that we can take about this
heating agent wherever we like, and deal with it as we please, limiting it
in any way. I am obliged to deal carefully with it; but even that
circumstance will have an interest for you in watching the experiment.
Contact is now made. The electric current, when compressed into thin
conducting-wires offering resistance, evolves heat to a large extent; and
this is the power by which we work. You see the intense glow immediately
imparted to the wire; and if I applied the heat continuously, the effect
of the current would be to melt the wire. As soon as the contact is
broken, the wire resumes its former appearance; and now that we make
contact again, you perceive the glow as before. [The experiment was
repeated several times in rapid succession.] You can see a line of light,
though you can scarcely perceive the wire; and now that it has melted with
the great heat, if you examine it, you will perceive that it is indeed a
set of irregularities from end to end a set of little spheres, which are
strung upon an axis of platinum running through it. It is that wire which
Mr. Grove described as being produced at the moment when fusion of the
whole mass is commencing. In the same manner, if I take a tolerably thick
piece of platinum, and subject it to the heat that can be produced by this
battery, you will see the brilliancy of the effect produced. I shall put
on a pair of spectacles for the experiment, as there is an injurious
effect of the voltaic spark upon the eyes, if the action is continued; and
it is neither policy nor bravery to subject any organ to unnecessary
danger; and I want, at all events, to keep the full use of my eyes to the
end of the lecture.
You now see the action of the heat upon the piece of platinum heat so
great as to break in pieces the plate on which the drops of metal fall.
You perceive, then, that we have sufficiently powerful sources of heat in
nature to deal with platinum. I have here an apparatus by which the same
thing can be shewn. Here is a piece of platinum, which is put into a
crucible of carbon made at the end of one pole of the battery, and you
will see the brilliant light that will be produced. There is our furnace,
and the platinum is rapidly getting heated; and now you perceive that it
is melted, and throwing off little particles. What a magnificent
philosophical instrument this is. When you look at the result, which is
lying upon the charcoal, you will see a beautifully fused piece of
platinum. It is now a fiery globule, with a surface so bright, and smooth,
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