experimenters be worth anything.

The researches of most well-informed physical philosophers go to prove
that the conducting properties of bodies are augmented by cohesion, and
that heat is conveyed profusely and energetically through all solid and
ponderable substances. Thus gold, silver, and others of the most solid
metals are the best conductors. Next to the pure metals in conducting
powers are rocks, flints, porcelain, earthenware, and the denser liquids
as the solutions of the acids and alkalies. As a further evidence to
prove that the passage of heat through all substances is increased
by cohesion, even some of those which are known to be among the best
conductors are deprived of this property by a division or disintegration
of their particles. Pure silica in the state of hard, rock crystal is
a better conductor than bismuth or lead; but if the rock crystal be
pulverized, the diffusion of heat through its powder is very slow and
feeble. Heat is conducted swiftly and copiously through transparent
rock salt, but pulverization converts the solid mass into a good
non-conductor. Caloric has for the same reason a stronger affinity for
pure metals than for their oxides.

Again, wood is known to be a better non-conductor when reduced to
shavings or sawdust than when in the solid state. It is probably on this
account that trees are protected by bark, which is not nearly so dense
and hard a body as the wood. Wool, silk, and cotton are much diminished
in conducting qualities when spun and woven, for the reason that their
fibers are brought closer together.

Count Rumford discovered that hot water, at a given temperature, when
placed in a vessel jacketed with a clothing of twisted silk, and plunged
into a freezing mixture, cooled down to 185 deg. Fah. in 917 seconds. But