57S Dr Glover on the Colouring Matter of the 



The notions entertained at present by physiologists, with 

 regard to the operation of this pigment, are implicitly those of 

 Sir Everard. And what they are, will appear from the fol- 

 lowing brief quotation from an elementary work : — " The se- 

 cretion on the cutis vera, which gives the black colour to the 

 skin, appears to assist in fitting men for residence in hot cli- 

 mates, because although such skin, by absorbing more caloric, 

 rises to a higher temperature under the sun's rays than w^hite 

 skin does, yet it does not inflame so readily from a rise of tem- 

 perature." Dr Alison's meaning is, that although the skin of 

 a negro may rise to a higher temperature under the sun's 

 rays than a white skin in the same circumstances, yet the dark 

 skin is less likely to inflame at that higher temperature than the 

 white skin at that lower one. This, then, is the conclusion of 

 Sir Everard Home, whose paper I now proceed to examine. 



The paper of Sir Everard Home contains alleged facts and 

 experiments, tending to prove the Negro more capable of with- 

 standing excessive heat of the sun's rays than the white man, 

 and attributing this to a supposed property in dark surfaces 

 of destroying the scorching and blistering effect of the sun's 

 rays. The former conclusion has already been admitted. The 

 facts by which Sir Everard supports his second position are to 

 be considered. 



Sir Everard having fallen asleep on the deck of a vessel ex- 

 posed to a tropical sun, found, on awaking, his thigh scorched 

 through a pair of thin white linen trousers. From this simple 

 observation, the extravagant conclusion is drawn of black be- 

 ing a better protection against the sun's rays than white. 



An experiment is next related, in which Sir Everard found, 

 on exposing his hand to the sun's rays for 45 minutes, while a 

 thermometer attached to it stood at 90°, that blisters rose and 

 coagulated lymph was exuded, I have attempted to produce 

 the same effect by the concentrated rays of the sun at the same 

 temperature indicated in a similar way, and kept up to within 

 one or two minutes of the time, when my patience was ex- 

 hausted, without any result except slight reddening. Six years 

 ago, while off the coast of Algiers, I sat for half an hour im- 

 moveable in the sun, having the greater part of my faco ex- 



