Cork insulation; a complete illustrated textbook on cork insulation ...

CORK INSULATION
Part II—The Study of Heat
CHAPTER VII.
HEAT, TEMPERATURE AND THERMAL EXPANSION.
31.—Molecular Theory of Heat.—The sensation of heat is
normally recorded by the sense of touch if heat is transferred
from a gas, liquid or solid to the human body ; and the sensation
of cold results from a transfer of heat from the human
body to a gas, liquid or solid. For the purpose of our study
of heat, it will be best to think principally in terms of heat,
rather than in terms of cold.
For many centuries it was generally believed that heat
was an invisible, elastic and weightless fluid, termed caloric,
which was responsible for all thermal phenomena by entering
gases, liquids and solids in some mysterious or hypothetical
manner, possibly even combining temporarily with them. It
was not until about the beginning of the nineteenth century
that the materialistic conception of heat was rather definitely
disproven by certain experiments conducted by Count Rum-
ford (Benjamin Thompson) (1753-1814), an American philosopher
who made important contributions to physics and
agriculture and later become adviser to the King of Bavaria,
and by Sir Humphry Davy (1778-1829), an English chemist.
But it remained for James Prescott Joule (1818-1889), an
English physicist, to prove, about the middle of the nineteenth
century, that a definite amount of mechanical work is equiv-
alent to a definite amount of heat, when it soon became evi-
dent that heat is a form of energy.
The kinetic theory of heat holds, briefly, that the molecules
of a body have a certain amount of independent, though irregular,
motion, and any increase in the energy of that motion
manifests itself in the body becoming warmer, and any de-
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