effect, and consequently of the quantity lost by the only substance that
could possibly have supplied it.
I have made this supposition of what would take place in a hollow sphere
of ice, for the purpose of more readily explaining the method used in
this species of experiment, which was first conceived by Mr de la Place.
It would be difficult to procure such spheres of ices and inconvenient
to make use of them when got; but, by means of the following apparatus,
we have remedied that defect. I acknowledge the name of Calorimeter,
which I have given it, as derived partly from Greek and partly from
Latin, is in some degree open to criticism; but, in matters of science,
a slight deviation from strict etymology, for the sake of giving
distinctness of idea, is excusable; and I could not derive the name
entirely from Greek without approaching too near to the names of known
instruments employed for other purposes.
The calorimeter is represented in Pl. VI. It is shown in perspective at
Fig. 1. and its interior structure is engraved in Fig. 2. and 3.; the
former being a horizontal, and the latter a perpendicular section. Its
capacity or cavity is divided into three parts, which, for better
distinction, I shall name the interior, middle, and external cavities.
The interior cavity f f f f, Fig. 4. into which the substances
submitted to experiment are put, is composed of a grating or cage of
iron wire, supported by several iron bars; its opening or mouth LM, is
covered by the lid HG, of the same materials. The middle cavity b b b
b, Fig. 2. and 3. is intended to contain the ice which surrounds the
interior cavity, and which is to be melted by the caloric of the
substance employed in the experiment. The ice is supported by the grate
m m at the bottom of the cavity, under which is placed the sieve n
n. These two are represented separately in Fig. 5. and 6.
In proportion as the ice contained in the middle cavity is melted, by
the caloric disengaged from the body placed in the interior cavity, the
water runs through the grate and sieve, and falls through the conical
funnel c c d, Fig. 3. and tube x y, into the receiver F, Fig. 1.
This water may be retained or let out at pleasure, by means of the
stop-cock u. The external cavity a a a a, Fig. 2. and 3. is filled
with ice, to prevent any effect upon the ice in the middle cavity from
the heat of the surrounding air, and the water produced from it is
carried off through the pipe ST, which shuts by means of the stop-cock
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