On the Power of Fluids to conduct Heat. 397 
Count Rumford attempts to explain why 
there was less ice melted in such experiments as 
the 4sth than in those like the 39th, and attri- 
butes the diminution of the effect to the de- 
scending currents, occasioned by the cold mix- 
ture surrounding the warm one, which he thinks 
would obstruct the opposite ones ascending from 
the ice. But the effect in the 51st, compared 
with the 53d, being just opposite, he passes 
over without explanation.—I have no doubt my- 
self, but that the true cause of the differences in 
both cases, is to be found in the column expres- 
sing the mean temperature of the water, and noi 
in that expressing its situation, which I consider 
as having nothing to doin the business, but as 
it affects the general temperature. The maximum 
effect with cold water will be when it is of the 
‘temperature of about 48° or 50°, and the mz- 
mum above it probably about 100° or 120°; 
and in proportion as the mean temperatures, 
in any experiment, deviate from those points, 
the effects vary accordingly, let other circum-. 
stances be what they may. 
Thus I have attempted to explain the ra- 
tionale of these very curious and interesting ex- 
periments, in a manner different to what their 
ingenious author has done. And must now leave 
it to the reader to form his opinion, 
