688 SECRETION AND ABSORPTION B Y THE SKIX. 
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 Eindfleisch, 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 the fact that by taking advantage 
of the cataphoric action of the galvanic current (so-called electro- 
osmose), 5 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 anaesthetised 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 Malpigbii 
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. Toxicologic," Berlin, 1874, S. 212. 
2 Loc. cit. s Diss. Wiirzburg, 1854. 
4 Arch./. Dcnnat. u. Syph., Wien, Bd. iii. S. 309. 
5 Neumann, Wien. med. Wchnschr., 1872. 
6 Porret, Ann. d. Phys. u. Chem., Leipzig. Bd. lxvi. S. 272 ; du Bois-Reymond, Mamatsb. 
Aland, 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. ncir. d. sc. evades {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. 
