It has been already mentioned that burning renders the negro skin white ; and this cause might have been supposed to have operated in the following instance, had it not been expressly mentioned that the person was always well clad, and that the parts exposed to the kitchen fire were not more particularly affected than such parts as were not so exposed. A cook-maid, a na tive of Virginia, whose skin was originally as dark as the most swarthy African, underwent a change of com plexion when she was about 25 years of age : this change made its first appearance on the skin near the finger nails ; the skin of the face, particularly near the mouth, was afterwards affected ; and the change gradually pro ceeded, till at last four parts out of five of her face and body became w bite ; her neck and back remained the blackest. This change was different in its nature from that of the former case ; for, in this instance, the skin became transparent, similar to that of a fair European, so that blushes could be discovered, and freckles took place ; the hair was also changed to white on those parts of the body which had become white, while it continued black on those parts wnich preserved their native colour. Philosophical Transactions, vol. xli. p. 176.
But the case most similar in its nature, and most particularly described, is given in the Manchester Trans actions, vol. v. part. 1. p. 314. The paternal grandfa ther of Henry Moss, (the person in question,) was born in Africa, and married a native Indian of Pennsylvania. His father married a mulatto born of an African father and an Irish mother. His maternal grandfather was born in Africa. Ile himself, till he arrived at the age of 40, was of as dark a complexion as any African: a change of colour then began to take place ; it commen ced at the skin near the root of his finger nails. It is remarkable that the change proceeded most rapidly and regularly, during the summer season ; during winter it either was entirely suspended, or went on so as scarcely to be perceptible. He felt, or fancied him self, more sensible to variations of temperature, after this change of colour took place, than he had been be fore. The change in the colour of his hair proceeded along with the change in the colour of his skin ; and wherever it became white, it became also soft, like the hair of Europeans, and could be drawn out to the length of several inches. Mr Fisher, who transmitted the ac count of this phenomenon, ascertained that the change of colour was not external, but a change of the rete mu cosum ; for when he pressed the skin it appeared white, and on the removal of his finger, it was suffused with red, as in Eu•opeans-t The oxymuriatic acid has a temporary effect on the black pigment, which exists in the retc mucosum of ne groes. Dr Beddocs subjected the fingers of a negro to
the action of this acid ; the skin was whitened, but the bl k co,our [...turned in a short time. This experiment has been repeated on the feet of a negro. Tney were kept for a considerable period in water, impregnated with ox inuriatic acid, which deprived the rote mucosum of its colour, rendered it nearly white ; but in a few days the black colour returned with its former inten sity.
II. Various hypotheses have been suggested to ac count for the imnwhate cause of the black complexion of negroes, by Mecket, Nuw, Walter, Kant, Illumen bach, Rush, and Humboldt.
I. The hypotheses of Mecket and Pauw nearly coin cide, and seem to have been derived from an observa tion of I ferodotus. This historian asserts that the sper matic fluid, both in the eastern and western Ethiopi ans, is not white as in other men, but black like their skin. (llerodotus Thalia, cap. 101.) Tnis opinion is expressly denied by Aristotle, but it is supported by the authority of Le Cat, in his Trot? sur la Couleur de la Peau. From this colour of the spermatic fluid, Mec ket and Pauw supposed that all the other fluids of the negroe,§ received it dark tinge. The former believed that th liquor, which colours the medullary substance of the brain, was darker coloured in the African than in the European ; this he supposed arose from the co lour of the spermatic fluid, and being secreted by the cutaneous nerves into the viscous reticular substance, contributed towards the dark complexion of the mucous membrane. But Soemmering expressly denies the alle gation on which this hypothesis rests: he could not observe the smallest difference in colour, either in the ceneritious or medullary parts of the brain of an Afri can and European; and, notwithstanding the authority of Le Cat, the blackness of the spermatic fluid of the negro may very justly be doubted.
2. Professor NValter is of opinion, that the blood of negroes is of a darker colour than that of Europeans, and that this is the cause of their dark complexion. This opinion is also maintained by Town, in his Paper on the Blood of Negroes, in the Philosophical Transactions; and Professor Soemtnering seems rather disposed to adopt it ; but the fact is very questionable. Professor Cam per asserts that the blood of negroes is not darker co loured than is frequently found among Europeans ; and Dr \Vinterbottom, who must be allowed to be a compe tent judge on this question, expressly maintains, " that there is no preceptible difference in the colour of the blood of an African and European." White rbottom's .leectint of the native Africans in the neighbourhood of Sierra Leone, vol. i. p. 191.