This paper published in 1984 describes a little known experiment in radiant cooling done in the late 18th century by Pictet and repeated a few years later by Count Rumford. http://www2.ups.edu/faculty/jcevans/Pictet's%20experiment.pdf What we usually hear about Rumford is his canon boring evidence against the caloric theory of heat. However, less well known is his theory of frigorific rays.He held that cold emanations were as real as hot emenations and he interpreted the Pictet experiment as evidence of his theory. In the paper the radiant cooling effect observed is explained using modern radiantive heat transfer theory. However, the geometric symmetry of the experiment does not invalidate the existence of frigorific rays. Although Rumfords "acoustic" [my label] conception of frigorific rays has some predicative problems, what interests me was his intuition that cold is more than
just the absence of heat, i.e. that cold has some positive existence. I think it is possible to redesign the experiment so that it would either clearly support Rumfords intuition or dispose of it. It is relevant to note that well before Rumford, Francis Bacon also regarded cold as having an independent existence from heat, although his particular of conceptions of cold as a "contractive power" and heat as an "expansive power" were different from Rumford's. Harry
