[ I2 4 ] 
the Skins of Negroes tranfmit no Colour or Rays of 
Light thro’ them, on account of the Thicknefs of 
their Subftance, and Denfity of their Texture, in the 
fame manner as they are imperfedly tranfmitted in 
fome white or tawny People, whofe Skins appear to 
be of the fame Structure with thofe of Negroes, and 
to differ from them in nothing, but in Degree of 
Thicknefs and Denfity, and in Colour j which dif- 
ferent Denfity may therefore probably be one, if not 
the only Caufe of this Difference of Colour. So that 
the Thicknefs and Denfity of the Skins of Negroes 
feems to be the grand Caufe of their Colour, in the 
fame manner as it is of Indians , Moors> &c. Which 
may be further confirmed by the following Confi- 
derations : i. In the Cicatrices of their Ulcers, the 
thin and tender new-form’d Skin appears whitifh, 
nay, perfectly white, in fome, cfpecialiy on the Shins, 
or thofe. Places where thefe Cicatrices are thin ; bur, 
where the Skin is thick, or when thefe Cicatrices 
turn more thick and callous, they grow blacker in 
Proportion 5 as in thofe Places where the Scars grow 
thicker than the reft of the Skin, they are likewife 
blacker. 2. The Colour of the Water, contained in 
the Blifters of white People, may be plainly feen 
thro’ their Cuticles, efpecially if tinctured yellow, 
which cannot be perceived in the Blifters of Negroes: 
A plain Proof, that their Cuticles are not tranfparenr, 
as thofe of white People are. 3. Infant-Negroes, 
whofe Skins differ from Adults only in theThinnefs 
and Parity of their Texture, look whitifh, in com- 
panion to adult Negroes 3 but grow bl.ick, as their 
Skins turn thicker and denfer. Thefe Infant Negroes, 
labouring under an Uterus , look of a yellow Colour, 
1 all 
