ABSORPTION B Y THE SKIN IN MAN. 685 
Absorption by the Skin. 
Man. — To decide the case for or against the possibility of absorption 
by the human skin, would appear a simple problem, yet a literature 
reaching back over a century indicates that the production of un- 
impeachable testimony on either side has proved a matter of no little 
difficulty. 
A fluid in contact with the skin is separated from the blood vessels 
by layers of epidermic cells with intercellular spaces, but since the 
superficial cells (except in the palm of the hand and sole of the foot) 
are greasy with sebum, one of the first conditions for absorption is that 
the fluid shall be able to wet the surface, so that imbibition by the cells, 
or entrance of the fluid into the capillary spaces between them, may 
take place. Though lanoline, the natural fat of the skin, takes up 
water, such action only occurs slowly, and unless the skin is soaked 
long in warm water, it is a familiar observation that it does not easily 
become sodden, except in the case of the palms and soles. It is there- 
fore not to be expected that water or watery solutions will be capable 
of absorption by the skin of man, and the experimental evidence is 
distinctly against such an assumption. 
The method of some of the older observers, of attempting to decide 
the question of absorption of water by immersing a man in a bath after 
weighing, and weighing again after a prolonged sojourn therein, we may 
dismiss by a bald statement of obvious sources of error. 
(a) There is no guarantee that the normal loss of weight of the body 
per unit time, through lungs and skin, is the same during the bath as 
estimated during preceding hours. (The experiments showed, in different 
instances, gains, losses, and absence of change of weight.) 1 
Further, mere soakage of the epidermis of palms and soles may 
mask an actual loss of weight in the bath.' 2 
(b) It is impossible to be certain that the epidermis of the whole 
body is devoid of fissures through which water might reach the deeper 
parts. 
(c) It is difficult to totally exclude absorption by immersed mucous 
surfaces. 
(d) A balance sensitive enough to indicate a difference of a few 
grammes on a weight of many kilos., is difficult to construct. 
(e) A considerable loss of surface epidermis occurs in " drying " the 
body with a towel. 
An improvement upon the method of total immersion is that of 
immersion of a part of the body, but the vessel, instead of being 
weighed before and after immersion of the part of the body, as in the 
experiments of Vierordt and Eichberg, 3 is better graduated as in the 
experiments of Falck, 4 or provided with a capillary pipette, by means of 
which absorption can be determined by fall of level of fluid, 5 because, 
by the gravimetric method, the error from mere soakage of epidermis 
becomes far larger than in the volumetric method, though here also a 
slight diminution in volume accompanies imbibition by the palm or sole, 
1 Jatnin et de Laures, Compt. rend. Acad. d. sc, Paris, 1872, tome lxxv. p. 60. 
2 Poulet, ibid., 1856, tome xlii. p. 435. 
3 Arch./, physiol. Heilk., Stuttgart, 1856. 4 Ibid., 1852. 
5 Madden, "An Experimental Inquiry into the Physiology of Cutaneous Absorption," 
Edinburgh, 1838 ; Fleischer, Inaug. Diss., Erlangen, 1877. 
