the Elementary Law of Hydrodiffusion. 

 Solution with the Concentration 0*214. 



535 





T. 



k. 



Nov. 14 



180 



190 

 176 

 18-8 

 171 

 16-9 



02399 

 0-2435 

 0-2397 

 0-2428 

 0-2384 

 0-2377 



Nov. 17 



Nov. 18 



Dec. 21 



Dec. 23 



Dec. 27 





Mean 



179 



0-2403 





Solution with the Concentration 0*318. 





T. 



7c. 



Nov. 10 



o 



181 

 18-9 

 181 

 17 9 

 173 

 178 



0-2297 

 0-2331 

 0-2288 

 0-2306 

 0-2248 

 02264 



Nov. 11 



Nov. 12 



Dec. 20 



Dec. 22 



Dec. 24 





Mean 



180 



0-2289 





It hence follows that the diffusion-quantity h is not inde- 

 pendent of the concentration, but diminishes, though very 

 slowly, with ascending concentration. 



In the theory of diffusion, therefore, Fick's elementary law 

 requires correction in the same manner as Fourier's elemen- 

 tary law in the theory of heat-conduction : as there the 

 quantity of the internal conduction slowly diminishes as the 

 temperature rises, so here the quantity of the diffusion gradu- 

 ally sinks to smaller values as the concentration increases. 

 Fick's hypothesis expresses the course of diffusion with only 

 the same accuracy with which Fourier's elementary law re- 

 presents the process of the conduction of heat in rigid sub- 

 stances. 



Appendix. — Remarks on so-called Unpolarizable Electrodes. 



Dubois-Reymond, in 1859, ascertained that the polarization 

 of amalgamated zinc electrodes in aqueous solution of sulphate 

 of zinc, on the employment of extremely feeble polarizing 

 currents, is vanishingly little^ at all events incomparably less 

 than that of any other combination. He thought that the 

 combination amalgamated zinc electrodes in zinc-sulphate 

 solution might with reason be designated " unpolarizable." 



These experiments have hitherto been misconceived, almost 

 without exception, by all who have reported thereon. Although 

 from Dubois-Revmond's statements it is evident that the 



