Fire is not hot, although it burns the flesh and promotes pain.
Matter, which is unalterable, cannot be made hot or cold, neither
is there anything to make it so. If a limb be made rigid, or the
nerves of sensation be removed, or the function of the nervous fluid
be obstructed, the limb may be burned off unconsciously. Heat is a
sensation effected through excitement of the brain; out of the brain
there is neither excitement nor heat. The fire does not excite the
brain, but the nervous fluid; and although the sensation is not hot, it
is imagined that the cause must be hot, which is false reasoning. The
chymist finds heat creviced in all things, even those which he admits
are destroyed by heat--gunpowder and ice. How can flame be hot, when
just obtained from the gases of decomposed ice water? or, if hot, _sui
generis_, it must have been hot frozen flame in the original ice.
Modern philosophy adopts different kinds of heat,--_animal, culinary,
and latent heat_. The first is our own feeling excited by means of
fire in the sensitive centre, the brain; also by exercise and disease,
in the absence of fire. How is the spark from the flint or from the
steel to saturate a bushel of coal with heat? How, again, does "heat
come to an equilibrium in all surrounding bodies," when some portion
of the coal may be black cold, and others red hot--using the popular
terms--in the fire-place, at the same time, and while the air in the
chamber is indexing zero? _Latent heat_ is of the philosopher's own
peculiar making; and on the "_great discovery_" the most unbounded
praise is still bestowed. Latent heat, "which all bodies possess
without being heated," which, "heats nothing," and is not hot, is
cold heat, and should be nomenclatured such, or, absurd heat. Are not
Instructors less than half-reasoners and unnatural philosophers, who
abide by and teach such consummate nonsense: on a par with which is
the discovery of "latent dark light"--"of black being formed by the
intermixture of two luminous rays at the point of intersection in
the spectrum," which is the same as feelable darkness; after which,
there only remains for "_new discovery_," latent sound, for inking
on, thence vibrating from, a sheet of music-paper; and latent motion,
to keep a stone at rest, the quantity of motion in the world having
been already ascertained arithmetically to a fraction; the last-day
discovery, the quantity of right reason, is the small remaining trifle
to be discovered. Radiation of heat and cold by fire and ice, being
inconsistent with the _inertia_ of _matter_, is an erroneous and
greatly-misleading assumption, although proved through the nicest
experiments, according to the experimenter's ideas.
Instead of fire communicating anything to bodies, _fire promotes loss
to everything_ in its neighbourhood. The bars of stoves, iron pokers,
steam-boilers; all culinary vessels; coal, wood, candles, paper, linen,
all suffer loss by means of fire; cinders, charcoal, tinder, are but
remains: to which it is no exception that some bodies acquire substance
and weight in becoming oxydes; because, previous to acquiring oxygen
from the air, they must have lost elementary matter to the fire to make
spaces for the oxygen to enter, otherwise the open air should oxydize
equally, in the absence of fire.
The loss, or matter of loss which fire promotes to fluids, appears as
air-beads on the sides and bottom within the vessel on the fire, before
the water comes to ebullition: these beads cannot be made to rise in
the water by any manner of agitation, which is proof they have not
come from the fire, and through the rigid bottom, or ascent and escape
are inevitable. When the bottom has been sufficiently de-electrised by
the fire, they are pressed through it to the fire; or if the vessel be
removed and placed on the ground, they become dispersed through the
water insensibly. The like spherules collect on an egg while boiling,
which cannot be anything issued from the fire to the surface of the
water, then precipitated on the egg. On the bottom of a glass-retort
suspended over a lamp, the like spherules collect, from which it is
supposed that water never touches the bottom of any containing vessel;
it must touch that which it wets.
That air suffers loss to fire, is made evident by the air being
deprived of, or losing its oxygen during combustion; and from both fire
and flame becoming extinguished in a limited quantity of respirable
air, in consequence of having lost its oxygen to the combustible, while
in the state of fire.
Solids, as polished metals and glass, when they experience no change
of weight, lose to the fire imponderable elementary matter only. So is
it when the hand is presented to the fire, it loses electric matter,
and the loss it suffers promotes the sensation of heat: when the hand
afterwards touches a body, supposed to be cold, it acquires elementary
matter from that which is touched. In every instance the body, solid or
fluid, supposed to be _heating_, is losing elementary matter; and that
which is said to be _cooling_, is acquiring the like matter; the hand
_loses_ to the former and _receives_ from the latter electric matter.