1817.) On the Chemical Phenomena of Heat. 425 
between the particles of every body, and that the sensations of heat 
are produced by the motion of this matter of heat or caloric; thus 
a body will feel hot which imparts a portion of this fluid to the hand, 
and cold if it abstract it. Upon this principle may most of the 
phenomena of heat be explained. All those chemists whose 
writings upon the subject I have seen have made very erroneous 
statements respecting it, which certainly lead to conclusions which 
must overturn the system, when investigated, unless properly ex- 
plained; and those who have objected to the hypothesis have prin- 
cipally attacked facts little connected with the subject, such as the 
addition of heat not increasing the weight of a body in any sensible 
degree, whilst real errors in principle have been entirely over- 
looked. Only one of these will be examined at present. Caloric 
is supposed to be attracted by the particles of ponderable matter 
surrounding each, or an atmosphere which decreases in density as 
we recede from the centre of the particle; and that calorific repul- 
sion is in proportion to the density. In solids the centripetal force 
is supposed to exceed this repulsive power, otherwise the particles 
submitted to the operation of these forces could not be held toge- 
ther; and yet, to account for the phenomena of expansion and 
contraction, these particles are assumed not to be in contact with 
each other. Now, if the centripetal be the predominating force, 
how can these particles be kept asunder? The absurdity must be 
evident to every one who gives the subject one moment’s considera- 
tion. Caloric certainly is attracted by the particles of ponderable 
matter; for if a bar of metal be heated at one end, the other soon 
becomes hot; this heat can only be conducted in consequence of 
its being successively attracted by the different particles which com- 
ose the bar. 
Of the form of the corpuscules, atoms, or particles of matter, we 
have no certain knowledge. They are most probably spheres. They 
may with safety be assumed of a spherical form; as that figure, of 
all others, is the most simple, and will answer every condition re- 
quired, as I shall subsequently demonstrate. They have been 
assumed by some of a spheroidal form, in consequence of the 
forms of some crystals, and the supposed harmony which exists, if 
this be the shape, between the figure of the ultimate atoms of 
matter and the planetary bodies. For this there is no necessity, 
since we are assured that this figure of the planets arises entirely 
from their diurnal rotation, and could not be produced unless they 
consisted of an indefinite number of minute particles of matter, 
which cannot be the case with the particles under consideration ; 
therefore the spherical, and not the spheroidal figure, is in harmony 
withthat of the planetary bodies. However, as we have no evidence 
to the contrary, I shall assume all bodies in nature to be composed 
of minute spherical atoms. 
Since caloric is attracted by the particles of matter, it must sur- 
round each as an atmosphere, whose density diminishes more ra- 
