95 
other bodies, and to the de- 
velopment of mechanical 
power by expansion. 
[2dly, A change of volume ; 
which, under a constant pres- 
sure, is an increase for every 
substance, except some liquids 
near their freezing points.] 
odly, A change of mole- 
cular condition ; as from the 
solid to the liquid state, or 
from the liquid or solid to the 
gaseous state, or any imper- 
ceptible change of molecular 
arrangement ; the change to 
the gaseous state being always 
accompanied by an increase 
of volume. 
The heat which produces 
[the first of] those effects is 
known by the name of sensible 
heat , as retaining the form of 
heat, and, in short, making 
the body hotter. 
[The heat which produces 
the second and third of those 
effects is called latent heat, as 
having disappeared in de- 
veloping a mechanical effect, 
and being capable of repro- 
duction by reversing the 
change which caused it to 
disappear.] 
8. It is evident that the omission of the words in brackets 
has the effect of precisely reversing the meaning of the 
definition which I have given of sensible as distinguished 
from latent heat. 
