520 PHYSIOLOGY CHAP. 



If, instead of aqueous solutions, fluids capable of softening and 

 dissolving the sebum of the epidermis, e.g. ether and alcohol (not 

 chloroform which irritates the skin), are employed, a certain 

 amount of absorption can easily be detected, more with ether 

 'which is a better solvent of fat, less with alcohol which dissolves 

 fat less easily. Winternitz (1891) demonstrated the presence of 

 lithium in urine by the spectroscope, after steeping the skin of the 

 forearm for three and a half hours in an ethereal solution of 

 lithium chloride, to which a little alcohol had been added ; with 

 purely alcoholic solutions the results were negative. After 

 previously smearing the skin with ether, he found a slight 

 absorption of lithium, after keeping the forearm nine hours in a 

 watery solution of lithium salts. This experiment proves that it 

 is the cutaneous sebum which makes the skin refractory to 

 absorption. 



By means of the catapJioretic action of the galvanic current 

 (also known as electrical endosmosis), it is possible to drive the 

 aqueous solutions through the skin, and to produce absorption by 

 the blood and lymph paths (Pascheles, 1895). The amount of 

 substance absorbed increases with the strength of current, but 

 beyond a few milliamperes the galvanic current damages the skin. 

 This method is therefore of little use in therapeutics. 



It has often been debated whether volatile substances, e.g. 

 tincture of iodine, applied to the skin can be absorbed by it. The 

 positive data of Kohrig are contradicted by the negative results of 

 Fleischer, who took every precaution to exclude absorption of 

 iodine by the respiratory passages. Mesnil (1894), on keeping his 

 arm for thirty-two hours in a glass cylinder filled with iodine 

 vapour, observed no absorption. On the other hand, Sciolla 

 (1893), Linossier and Lannois (1894), Guinard and Stoorbe (1894), 

 obtained absorption of guaiacol when applied to the skin. 



Oily substances and unguents applied to the skin are not 

 absorbed (Baschkis, Obermayer, Fleischer, Fubini and Pierini). 

 But if the skin be rubbed hard for a long time with these 

 unguents, so that they are mechanically pressed into the hair 

 follicles, gland ducts and intercellular spaces of the epidermis, 

 absorption not only of the dissolved substances but also of the 

 suspended corpuscles can be obtained. From a therapeutic point 

 of view the most important fact is the absorption of mercurial 

 salves with friction (Kulzer, Neumann, Fiirbringer, and others). 

 Voit demonstrated that mercury in the form of metal spherules 

 can be forced into the human corpse, by energetic rubbing, not 

 only between the layers of the epidermis, but also into the corium. 

 But in the living subject, the mercury on coming in contact 

 with the sodium chloride of the sweat is probably converted into 

 calomel, and partially into sublimate, and absorbed in that form. 



The results of experiments on cutaneous absorption in mammals 



