130 Count Rumford’s Enquiry concerning the Nature of Heat, 
temperature which take place in the air ; and the less will he 
be oppressed by the intense heats of hot climates. 
It is well known that negroes, and people of colour, support 
the heats of Tropical climates much better than white people. 
Is it not probable that their colour may enable them to throw off 
calorific rays with great facility, and in great abundance ; and 
that it is to this circumstance they owe the advantage they 
possess over white people, in supporting heat? And, even should 
it be true, that bodies are cooled, not in consequence of the 
rays they emit, but by the action of those frigorific rays they 
receive from other colder bodies, (which I much suspect to be 
the case,) yet, as it has been found by experiment, that those 
bodies which emit calorific rays in the greatest abundance, 
are also most affected by the frigorific rays of colder bodies, it 
is evident, that in a very hot country, where the air and all other 
surrounding bodies are but very little colder than the surface 
of the skin, those who by their colour are prepared and disposed 
to be cooled with the greatest facility, will be the least likely to 
be oppressed by the accumulation of the heat generated in them 
by respiration, or of that excited by the sun's rays. 
With a view to throw some light on this interesting subject, 
I made the following experiments. 
Exper. No. 27. Having covered the flat ends of both my 
horizontal cylindrical vessels with gold-beater's skin, I painted 
one of these coverings (of this animal substance) black, with 
Indian ink ; and then, filling both vessels with boiling hot water, 
I presented them, at equal distances, to the two opposite balls of 
the thermoscope. 
The bubble of spirit of wine was immediately driven out of its 
