d into the
degrees of temperature which it had above zero at the commencement of the
experiment, gives the proportion of what the English philosophers call
specific heat.

Fluids are contained in proper vessels, whose specific heat has been
previously ascertained, and operated upon in the machine in the same
manner as directed for solids, taking care to deduct, from the quantity
of water melted during the experiment, the proportion which belongs to
the containing vessel.

If the quantity of caloric disengaged during the combination of
different substances is to be determined, these substances are to be
previously reduced to the freezing degree by keeping them a sufficient
time surrounded with pounded ice; the mixture is then to be made in the
inner cavity of the calorimeter, in a proper vessel likewise reduced to
zero (32 deg.); and they are kept inclosed till the temperature of the
combination has returned to the same degree: The quantity of water
produced is a measure of the caloric disengaged during the combination.

To determine the quantity of caloric disengaged during combustion, and
during animal respiration, the combustible bodies are burnt, or the
animals are made to breathe in the interior cavity, and the water
produced is carefully collected. Guinea pigs, which resist the effects
of cold extremely well, are well adapted for this experiment. As the
continual renewal of air is absolutely necessary in such experiments, we
blow fresh air into the interior cavity of the calorimeter by means of a
pipe destined for that purpose, and allow it to escape through another
pipe of the same kind; and that the heat of this air may not produce
errors in the results of the experiments, the tube which conveys it into
the machine is made to pass through pounded ice, that it may be reduced
to zero (32 deg.) before it arrives at the calorimeter. The air which
escapes must likewise be made to pass through a tube surrounded with
ice, included in the interior cavity of the machine, and the water which
is produced must make a part of what is collected, because the caloric
disengaged from this air is part of the product of the experiment.

It is somewhat more difficult to determine the specific caloric
contained in the different gasses, on account of their small degree of
density; for, if they are only placed in the calorimeter in vessels like
other fluids, the quantity of ice melted is so small, that the result of
the experiment