1 24 Count Rumford’s Enquiry concerning the Nature of Heat , 
by an experiment made at Florence, towards the end of the 
seventeenth century. And it is not a little curious, that the learned 
academicians who made that experiment, and who made it with 
a direct view to determine the fact in question, were so com- 
pletely blinded by their prejudices respecting the nature of heat, 
that they did not believe the report of their own eyes; but, 
regarding the reflection and concentration of cold (which they 
considered as a negative quality) as impossible , they concluded, 
that the indication of such reflection and concentration, which 
they observed, must necessarily have arisen from some error 
committed in making the experiment. 
Happily for the progress of science, the matter was again 
taken up, about twenty years ago, by Professor Pictet; and 
the interesting fact, which the Florentine academicians would not 
discover, was put beyond all doubt. But still, this ingenious and 
enlightened philosopher did not consider the appearances of a 
reflection of cold, which he observed in his experiments, as 
being real ; nor was he led by them to admit the existence of 
frigorific emanations from cold bodies, analogous to those calo- 
rific emanations from hot bodies, which he calls radiant heat. 
He every where speaks of the reflection of cold (by metallic 
mirrors) as being merely apparent ; and it is on that supposition, 
that the explanation he has given of the phenomena is founded. 
On a supposition that the caloric of modern chemists has any 
real existence, and that heat, or an increase of temperature in 
any body, is caused by an accumulation of that substance in such 
body, the reflection of cold would indeed be impossible; and the 
supposition that such an event had taken place, would be absurd, 
and could not be admitted, however striking and convincing the 
