Nature of Caloric. 357 
ef Davy, as given in his Elements of Chemical Philosophy 
The substance of this hypothesis is, that the sda of 
smlimelteeticle-of lipids and Sianic fuide weavings tere 
q a ore gz, beside 
the vibratory motion in common with fluids, an additional 
motion round their own axes. 
‘¢ Temperature (says Davy) may be conceived to depend on 
the velocities of the vibrations; increase of capacity, or the 
motion being performed in greater space ; and the diminution 
of temperature, during the conversion of solids into fluids and 
gases, may be explained on the idea of the loss of vibratory 
motion, in consequence of the revolution of particles round 
their axes, at the moment when the body becomes liquid or 
zriform; or from the loss of rapidity of vibration, in conse- 
quence of the particles vibrating through greater space.” [| 
confess myself utterly unable to make any thing of this doc- 
trine, or to understand how it discloses the least analogy be- 
tween the properties of motion and the phenomena of heat; 
and I have long felt surprise, that a chemist so truly great, 
and so earnest as Sir Humphrey Davy has always been, to 
place the science of chemistry on its true basis of experiment, 
should, for a moment, have given way to a hypothesis, which 
savours more of the days of Alchymy or of Aristotle, than 
any thing to be met with since the age of Stahl. Dr. Hare, 
who is equally distinguished for brilliancy of invention and 
acuteness of reasoning, has attempted to refute this hypothe- 
sis by an argument of the nature of a reductio ad absurdum. 
He has attempted to show, that the supposition that tem- 
perature results from the velocity of the particles of heat- 
ed bodies, subjected to a vibratory motion, is inconsis- 
tent with the laws of mechanics. ‘“ It is fully established in 
mechanics (says Dr. Hare) that when a body in motion is 
blended with and thus made to communicate motion to anoth- 
er body, previously at rest, or moving slower, the velocity of 
the compound mass, after the impact, will be found, by multi- 
plying the weight of each body, by its respective velocity, 
and dividing the sum of the products by the aggregate weight 
of both bodies.” He then to show that the pheno- 
mena of temperature do not coincide with this law. Thus, 
when water and mercury of different temperatures, are add 
oge ther, the resulting temperature is not a mean, as it would 
