VOL. XLIII.3 PHILOSOPHICAL TRANSACTIONS. 68 



Hence, also, 1 . White spots on the skins of negroes are as common, and 

 proceed from the same causes with red spots on white people ; viz. a distention, 

 dilatation, and consequent rarity or pellucidity of the vascula of the epidermis : 

 whence the physical causes of the total whiteness of some negroes, at their birth, 

 may be accounted for. 



1. The hair of negroes becomes short, stiff, and frizzled, from the exsiccation 

 of its substance, and its excrementitious moisture, by the heat of the sun ; with 

 the thickness and density of the pericranium, which hinders it from being fur- 

 ther protruded. 



3. Many morbid discolorations of the body proceed rather from a preternatural 

 thickness and density of the membranes of the skin, than from any humours 

 lodged in them, as is commonly supposed ; and may be accounted for in the 

 same manner, as the different complexions in time of health. 



4. The bodies of whites are more perspirable than those of negroes, but per- 

 spire less in hot weather, and more in cold. 



5. White people are most healthy in cold, and black or tawny people in hot 

 countries ; each being subject to disorders, on a removal to these respective 

 climes. The causes of the diseases of white people in hot countries, are often 

 opposite and contrary to such as proceed merely from heat, which exalts the 

 fluids, exsiccates the solids, and quickens the circulation, occasioning severe 

 acute diseases ; but the thin and rare skins, and large pores of white people, 

 make them subject to too large cutaneous evacuations of the most subtil and 

 active fluids ; by which the body is enfeebled, and comes to be in an imbibing 

 state, both on its external and internal surfaces; and too readily imbibes the hu- 

 midity of the air and aliment, without a previous digestion ; causing a cold and 

 humid, rather than a hot and dry, state of the body ; from whence proceed their 

 lingering acute, and obstinate chronical maladies, more frequent in hot coun- 

 tries than the former, especially among the whites. Negroes, notwithstanding 

 their hardier usage, are more apt to have their perspiration obstructed in cold 

 weather, and thence contract fevers; whereas, in hot weather, their thicker 

 hides serve as a coat, to keep off the power of the sun, and preserve the body 

 against the moisture of the air, so remarkably great, and very pernicious in all 

 hot countries, especially at certain seasons, which are always sickly. Hence 

 white people should be best clothed in hot weather, and blacks in cold ; a thing 

 much neglected in Virginia, though the cause of one half of the untimely deaths 

 of both sorts of people in it. 



6. The perspirable matter of black or tawny people is more subtil and volatile 

 in its nature ; and more acrid, penetrating, and offensive, in its effects ; and 

 more of the nature, and more apt to degenerate to a contagious miasma, than 



