MEASUREMENTS OF ELECTROLYTIC MIGRATION 3 



EXPERIMENTAL METHODS. 



The experimental methods of determining migration values 

 are five in number : the analytical or Ilittorf method (pre- 

 viously used by Faraday and by Daniell and Miller), the direct 

 or meniscus-velocity method, the method based on measurement 

 of concentration cells with and without diffusion, the method 

 based on measurements of the limiting current density at which 

 normal products occur at the electrodes, and the method of 

 Nernst and Riesenfeld for two immiscible solvents with a linear 

 distribution ratio (Verteilungscoetlicient). 



Of these only the first two as yet yield accurate and reliable 

 results. The results of all five methods have been abstracted 

 in the present bibliography. 



The literature for the fourth method, mainly theoretical, is : 



H. W. Weber, Wied. Ann., 7, 469 and 536 (1879). 



A. Witkowsky, ibid., //, 759 (1880). 



C. L. Weber, Zeit. phys. Chem., ^, 182 (1889). 

 Sheldon and Downing, Phys. Rev., /, 51 (1893). 



B. Klossing, Beibl., 18^ 220 (1894). 



Th. des Coudres, Wied. Ann., 57, 232 (1896). 



E. Salomon, Zeit. phys. Chem., 2^, 55 (1897) ; ^j, 336 (1898). 



C. Ullmann, Zeit. f. Elektrochem., j, 516 (1897). 



H. J. Sand, Phil. Mag. (6), /, 45 (1901) ; Zeit. phys. Chem., 

 ?5, 641 (1901). 



C. Christiansen, Drudes Ann., ^, 787 (1902). 



P. Straneo, Ace. dei Lincei (5), // (I), 58, 171 (1902). 



F. G. Cottrell, Zeit. phys. Chem., ^^, 385 (1903). 

 U. Grassi, ibid., ^^, 360 (1903). 



E. Brunner, ibid., ^7, 56 (1904). 



ACCURACY OF THE DETERMINATIONS. 



The accuracy of transport determinations is usually much 

 overrated. For the better experiments of such workers as Bein, 

 Kiimmell, Loeb, and Nernst, and the best experiments of Hit- 

 torf, the results seem to be reliable to one or two units in the 

 second decimal place ; the work of Steele and Denison is more 

 accurate. Very accurate measurements ^ have been made with 



^Probably Tower's measurements of sulphuric acid fall in this class ; the ex- 

 perimental details are inaccessible in Heidelberg. 



