688 SECRETION AND ABSORPTION B Y THE SKIN. 



globules of mercury, there is present the black oxide of the metal, 1 

 and it is probable that, after formation of calomel by the sodic chloride 

 of the sweat, in the presence of oxygen a further conversion into 

 corrosive sublimate takes place, which is finally taken up by the blood. 



Though evidence of vaporisation of mercury in mercurial ointment , 

 at the body temperature, can be got by hanging a gold leaf over the 

 preparation, such vapour cannot of course pass through wet capillary 

 walls into the blood. The theory also of a passage of the fine globules 

 of mercury through into the blood is denied by Barensprung, 2 Hoffmann, 3 

 and Kindfleisch, 4 though the fine particles are certainly mechanically 

 forced into the hair follicles, sweat ducts, 5 and the interstices of the 

 superficial epidermic cells, thence to gradually undergo removal. 



Finally, mention may be made of he fact that by taking advantage 

 of the cataphoric action of the galvanic current (so-called electro- 

 osmose), 8 it is possible to force watery solutions into the capillary spaces 

 between the epidermic cells, and so artificially cause absorption, either 

 by subsequent diffusion into the blood vessels, or by the recoil of 

 distended spaces forcing fluid into lymphatic channels. 7 The direction 

 in which the fluid is moved is that of the electrical current, and the 

 quantity carried through a porous partition is directly proportional to 

 the intensity of the current, but organic membranes are far less 

 permeable than porous earthenware. 8 



It is not then to be expected that the effects with human skin 

 will be very marked, since, in practice, only a few milliamperes can be 

 passed with comfort to the patient. 



Munk 9 got evidence of iodine and quinine in the urine, with 

 positive electrodes of modeller's clay moistened with potassium iodide, 

 and quinine in aqueous solution. Herzog 10 amesthetised the skin with 

 cocaine solution on the positive electrode, when mere application without 

 passage of current was without effect, as also was passage of current 

 without cocaine. 



Kahn 11 corroborates this, getting complete anaesthesia of the skin in 

 twenty-five minutes, by a current of 4'5 milliamperes, with return of 

 sensation in thirty minutes after cessation of current. With a current 

 of 1 milliampere, the return of sensation was complete in ten minutes. 

 An excised piece of skin which had been anaesthetised by passing 3 - 25 

 milliamperes for thirty minutes through an anode filled with cocaine 

 solution tinged with a blue dye stuff, on microscopic examination showed 

 the dye stuff only to the depth of the rete Malpighii. 



Lower mammals. The results of observations upon absorption by 

 the skin of lower mammals are here considered apart from those obtained 

 from experiments on man, in order to obviate any tendency to treat the 



1 Barensprung, Journ.f.prakt. Chem., Leipzig, 1850, S. 50 ; Voit, Ann. d. Chem. , Leipzig, 

 1857, Bd. civ. S. 3; Hermann, " Lehrbuch d. exper. Toxicologie," Berlin, 1874, S. 212. 



2 Loc, cit. 3 Diss. Wiirzburg, 1854. 



4 Arch.f. Dermat. u. Syph., Wien, Bd. iii. S. 309. 



5 Neumann, Wien. med. Wchnschr., 1872. 



6 Porret, Ann. d. PTiys. u. Chem., Leipzig. Bd. Ixvi. S. 272 ; du Bois-Reymond, Monatsb. 

 Akad. d. Wissensch., Berlin, 1860, S. 846 ; Wiedemann, Ann. d. Phys. u. Chem., Leipzig, 

 1852, S. 321 ; and "Elektricitat," Braunschweig, 1883. Bd. ii. S. 166. 



7 Pascheles, Arch.f. exper. Path. u. Pharmakol., Leipzig, 1895, Bd. xxxvi. S. 100. 



8 Engelmann, Arch. neer. d. sc. exactes (etc.}, 1874, Bd. ix. S. 332. 



9 Reichert, Arch.f. PhysioL, Leipzig, 1873, S. 505. 



10 Miinchen. med. Wchnschr., Bd. xxxiii. S. 222. 



11 Inaug. Diss., Strassburg, 1891. 



