378 Onthe Power of Fluids to conduct Heat. 
ist. The internal motion of the liquid, by 
- which water of 32°, incumbent upon the ice, is 
perpetually ascending into a warmer region of 
53°, and watmer water of 42°: descending to take 
its place, 
od. The proper conducting power of the 
liquid independent of internal motion, 
gd. The conducting power of the glass 
jar. But as glass is known to be a very bad con- 
ductor of heat, it can produce no material 
effect in these experiments: For which reason 
Count Rumford does not appreciate the third 
cause. 
With respect to the operation of the first 
cause, it will generally be supposed that cold water 
rising into warmer and remaining with it, the 
heat is impaired, and the two reduced to a com-~ 
mon temperature. But Count Rumford does not 
admit of this communication; he maintains, that 
the two still retain there proper share of heat, 
notwithstanding they are mixed together. This 
hypothesis of his is of no peculiar consequence 
as far as respects the effect of the internal. 
motion: For the temperature indicated by a 
thermometer immersed in an equal mixture of 
water at 32° and 53°, would be the same.as if the 
water was uniformly of the temperature 42°. 
But it has material consequences in other re- 
spects; for, if it be admitted, it annihilates the © 
