and the Mode of its Communication. 133 
derive advantages from that practice, exactly similar to those 
which negroes derive from their black colour. 
It cannot surely be supposed, that I could ever think of re- 
commending seriously to polished nations, the filthy practices of 
these savages. That is very far indeed from being my inten- 
tion ; for I have ever considered cleanliness as being so indis- 
pensably, necessary to comfort and happiness, that we can have 
no real enjoyment without it ; but still, I think that a knowledge 
of the physical advantages which those savages derive from such 
practices, may enable us to acquire the same advantages, by 
employing more elegant means. A knowledge of the manner 
in which heat and cold are excited, would enable us to take 
measures for these important purposes with perfect certainty : in 
the mean time, we may derive much useful information, by a 
careful examination of the phenomena which occasionally fall 
under our observation. 
If it be true, that the black colour of a negro, by rendering 
him more sensible to the few frigorific rays which are to be 
found in a very hot country, enables him to support the great 
heats of Tropical climates without inconvenience, it might be 
asked, how it happens that he is able to support, naked, the 
direct rays of a burning sun ? 
Those who have seen negroes exposed naked to the sun's 
rays, in hot countries, must have observed that their skins, in 
that situation, are always very shining. An oil exudes from their 
skin, which gives it that shining appearance ; and the polished 
surface of that oil reflects the sun's calorific rays. 
If the heat be very intense, sweat makes its appearance at the 
surface of the skin. This watery fluid not only reflects very 
