ABSORPTION BY THE SKIN. 315 



of most interest to us as physiologists concerns the normal functions of the skin as an 

 absorbing surface. Looking at this subject from a purely physiological point of view 

 absorption from the skin, under ordinary conditions, must be very slight, if, indeed, it take 

 place at all. There are a few observations by the older physiologists which would at 

 first seem to show that a certain amount of water is taken up by the skin when the 

 atmosphere is unusually moist. In all of these, however, this conclusion is drawn from the 

 circumstance that the weight is occasionally somewhat increased under these conditions; 

 but no account is taken of the fact, that, when the surrounding atmosphere is moist, the 

 amount of the exhalations is greatly decreased. The lungs, also, present an immense 

 absorbing surface, which is not at all considered. Experiments on this point are not suffi- 

 ciently definite to warrant any positive conclusions ; but it is evident that, if any articles 

 enter in this way, the quantity must be excessively minute. 



The experiments upon the entrance of water and soluble substances through the skin, 

 when the body has been immersed for a long time in a bath, are somewhat contradictory. 

 Most experimenters have noted an increase in the weight, which they attribute to absorp- 

 tion of water, but others profess to have observed a slight diminution in the weight of the 

 body. In some experiments on this subject, by Madden, in which all necessary precau- 

 tions were adopted, the air being respired through a tube passed out of the window of the 

 room, so that no unusual absorption of moisture could take place by the lungs, the results 

 were very conclusive. In experiments of this kind, there are many modifying influences 

 to be guarded against. For example, it has been found to be important to regulate care- 

 fully the temperature of the bath ; for, when it exceeds that of the body, there may be a 

 loss of weight by cutaneous transpiration. It is stated by Longet that, when the tem- 

 perature of the water is lower than that of the body, there is a gain in weight ; but that 

 the cutaneous exhalation and absorption are balanced when the temperature of the bath 

 and the body are the same. There is another source of complication in these observa- 

 tions, which has been brought forward very strongly by a French writer, M. Delore. 

 This observer has carefully noted the increase in weight of the hair, nails, and epidermis, 

 after immersion for half an hour in distilled water, and has always found it to be v,ery 

 considerable. He assumes that this is more than sufficient to account for the increase in 

 the weight of the entire body after immersion in water for half an hour, which amounts 

 to about seven hundred grains. 



There are, nevertheless, facts which render it certain that water can be absorbed by 

 the skin. In an elaborate series of experiments by Collard de Martigny, it was proven 

 conclusively that water could be absorbed in small quantity by the skin of the palm of 

 the hand. In one experiment, a small bell-glass filled with water was applied hermeti- 

 cally to the palm. This was connected with a tube bent in the form of a siphon, also 

 filled with water, the long branch of which was placed in a vessel of mercury. After 

 the apparatus had been applied for an hour and three-quarters, the mercury was found 

 sensibly elevated in the tube, showing that a certain quantity of the water had disap- 

 peared. More recently, a very extended series of observations upon the absorption of 

 water and soluble substances has been made by Dr. Willemin, in which it is conclusively 

 proven that water is absorbed in a bath, and that various medicinal substances may be 

 taken up by the skin in this way and can be detected afterward in the urine. In a large 

 number of experiments, he found that the weight of the body, after remaining in a tepid 

 bath for from thirty to forty-five minutes, was generally stationary ; but that sometimes 

 there was a very slight diminution in weight and sometimes a very slight increase. By 

 comparative observations, however, he found that the diminution of weight in the bath 

 was always less than the amount lost by the same subject in the air. Dr. "Willemin 

 employed a very delicate apparatus for weighing, and his observations were apparently 

 conducted with great care. He also confirmed the statement of W. F. Edwards and 

 others, that transpiration from the general surface goes on in a bath. This he showed 

 by differences in the composition of the bath before and after immersion of the body. 



