CALORIC. 
all ; that of liquids is much smaller ; and that 
of solids the smallest of all. Thus, 100 cu- 
bic inches of atmospheric air, by being heat- 
ed from the temperature of 32° to that of 
212°, are increased to 137.5 cubic inches : 
while the same augmentation of tempera- 
ture only makes 100 cubic inches of water 
assume the bulk of 104.5 eubic inches: and 
100 cubic inches of iron, when heated from 
32° to 212", assume a bulk scarcely exceeding 
100.1 cubic inches. From this example, 
we see that the expansion of air is more 
than eight times greater than that of wa- 
ter ; and the expansion of water about 43 
times greater than tliat of iron. See Ex- 
pansion. 
All substances in nature, as far as we are 
acquainted with them, occur in one or 
other of the three following states ; namely, 
the state of solids, of liquids, or of elastic 
fluids or vapours. It has been ascertained, 
that in a vast number of cases, the same 
substance is capable of existing successively 
in each of these states. All solid bodies, a 
very small number excepted, may be con- 
verted into liquids by heating them sufii- 
ciently ; and, on the other hand, every li- 
quid, except spirit of wine, is convertible 
into a solid body, by exposing it to a suffi- 
cient degree of cold. All liquid bodies 
may, by heating them, be converted into 
elastic fluids, and a great many solids are 
capable of undergoing the same change ; 
and lastly, the number of elastic fluids 
which by cold are condensible into liquids or 
solids, is by no means inconsiderable. These 
facts have led philosophers to form this ge- 
neral conclusion, “ that all bodies, if placed 
in a temperature sufficiently low, would as- 
sume a solid form ; that all solids become 
liquids when sufficiently heated ; and that 
all liquids, when exposed to a certain tem- 
perature, assume the form of elastic fluids.” 
The state of bodies then depends upon the 
temperature in which they are placed ; in 
the lowest temperatures they are all solid ; 
in higher temperatures they are converted 
into liquids ; and in the highest of all they 
become elastic fluids. The particular tem- 
peratures at which bodies undergo those 
changes are exceedingly various, but they 
are always constant for the same bodies. 
Thus we see that heat produces changes on 
tlie state of bodies, converting them all, 
first into liquids, and then into elastic fluids. 
When solid bodies are converted by heat 
into liquids, the change in some cases takes 
place at once. There is no interval between 
solidity and liquidity ; but in other cases a 
veiy giadual change may be perceived j the 
solid becomes first soft, and it passes, 
through all the degrees of softness, till at 
last it becomes perfectly fluid. The con- 
version of ice into water is an instance of 
the first change ; for in that substance there 
is no intervening state between solidjty and 
fluidity. The melting of glass, of wax, and 
of tallow, exhibits instances of the second 
kind of change ; for these bodies pass 
through every degree of softness before 
they terminate in perfect fluidit}'. In ge- 
neral, those solid bodies which crystallize 
or assume regular prismatic figures, have no 
interval between solidity and fluidity ; 
while those tliat do not usually assume such 
shapes, have the property of appearing suc- 
cessively in all the intermediate states. 
Caloric not only increases the bulk of bo- 
dies, and changes their state from solids to 
liquids, and from liquids to elastic fluids ; 
but its action decomposes a great number 
of bodies altogether, either into their ele- 
ments, or it causes these elements to com- 
bine in a different manner. Thus when am- 
monia is heated to redness, it is resolved 
into azotic and hydrogen gases. Alcohol, 
by the same heat, is converted into carbu- 
rated hydrogen and water. 
This decomposition is in many cases ow- 
ing to the difference between the volatility 
of the ingredients of a compound. Thus, 
when weak spirits, or a combination of al- 
cohol and water, are heated, the alcohol se- 
parates, because it is more volatile than the 
water. In general, the compounds which 
are but little or not at all affected by heat, 
are those bodies which have been formed 
by combustion. Thus water is not decom- 
posed by any heat which can be applied to 
it ; neither are sulphuric, phosphoric, or 
carbonic acids. Almost all the combina- 
tions into which oxygen enters without 
having occasioned combustion, are decom - 
posable by heat. Tliis is the case with ni- 
tric acid, hyperoxymuriatic acid, and many 
of the metallic oxides. 
All bodies that contain combustibles as 
component parts are decomposed by heat. 
Perhaps the metallic alloys are exceptions 
to this rule ; at least it is not in our power 
to apply a temperature high enough to pro- 
duce their decomposition, except in a few 
cases. 
When two combustible ingredients and 
likewise oxygen occur together in bodies, 
they are always very easily decomposed by 
' heat. This is the case with the greater 
number of animal and vegetable sub- 
stances. 
Having examined the nature, and some 
t 
