373 
EXPERIMENTS and OBSERVA- 
TIONS on the Power of Fluids to conduct 
HEAT ; wth Reference to Count Rum- 
ford’s Seventh Essay on the same Subject. 
BY JOHN DALTON, 
READ APRIL 12TH, 1799. 
if be nature and properties of fire or heat are 
subjects which present themselves to our con- 
sideration in almost every department of physics : 
It is no wonder therefore that new experiments, 
which point out and define the modes of opera- 
_ tion of fire, before unobserved, or at least too 
much overlooked, should attract the attention of 
philosophers.—These observations were suggest- 
ed upon reading Count Rumford’s very inge- 
nious experiments, in his essay abovementioned, 
which exhibit a fact in a more striking point of 
view than it has appeared before—namely, that 
the quickness of the circulation and diffusion of heat 
in fluids, 2s occasioned principally by the internal 
motion arising from a change of specific gravity 
effected by the heat.—But the conclusion he has 
drawn from them—that fluids are perfect non- 
