Take a stick of Glass of a considerable length, and fit it so between the
two ends or screws of a Lath, that it may but just easily turn, and that
the very ends of it may be just toucht and susteined thereby; then applying
the flame of the Candle to the middle of it, and heating it hot, you will
presently find the Glass to stick very fast on those points, and not
without much difficulty to be convertible on them, before that by removing
the flame for a while from it, it be suffered to cool, and when you will
find it as easie to be turned round as at the first.
From all which Experiments it is very evident, that all those Bodies, and
particularly Glass, suffers an Expansion by Heat, and that a very
considerable one, whilst they are in a state of Fusion. For _Fluidity_, as
I elsewhere mention, _being nothing but an effect of very strong and quick
shaking motion, whereby the parts are, as it were, loosened from each
other, and consequently leave an interjacent space or vacuity_; it follows,
that all those shaken Particles must necessarily take up much more room
then when they were at rest, and lay quietly upon each other. And this is
further confirmed by a Pot of _boyling Alabaster_, which will manifestly
rise a sixth or eighth part higher in the Pot, whilst it is boyling, then
it will remain at, both before and after it be boyled.
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