745 



bear into consideration, the lowering of the freezing point will again 

 become very small in this case. Since the tangential tension all along 

 the cylinder surface has the same value, equilibrium with the sur- 

 rounding liquid will now be possible. 



Haarlem, May 1914 Physical Laboratory of 



''Teyler's Stichting'. 



Physics. — "The effect of magnetisation of the electrodes on the 

 electromotive force." By Dr. G. J. Eltas. (Communicated by 

 Prof. H. A. LoRENTz). 



(Communicated in the meeting of June 27, 1914). 



1. The question in how far magnetisation of the electrodes is of 

 influence on the electromotive force in a circuit in which there are 

 electrolytes, has already often been examined, without it being 

 possible to derive a definite answer to this question from the results 

 of these researches. Thus Gross') found no definite direction of the 

 current in concentrated solutions of ferro salts, while in concentrated 

 solutions of ferri salts the magnetized electrode (both electrodes 

 consisted of iron) became the anode. Andrews ^) arrived at the same 

 result working with strong acids as electrolytes. Nichols and Franklin') 

 obtained results which were in concordance with those of Gross 

 and Andrews, in case a pole of a magnetized iron rod came in 

 contact with the electrolyte, which consisted of a solution of chromic 

 acid. In this case the electromotive force greatly increased with the 

 magnetisation, and reached the value of aboat 68 millivolts in a 

 field of 20000 Gauss. If on the other hand the neutral region of 

 the magnetized rod was in contact with the electrolyte, the sense of 

 the electromotive force was opposite. Rowland and Bell') found 

 that the magnetized electrode became cathode when acids that 

 attacked the iron, were used as electrolytes. Squier^), who took 

 nitric acid as electrolyte, came to the same result. The maximum 

 electromotive force amounted to 36 millivolts, in a field of 10000 



1) Th. Gross. Sitz. Ber. d. kais. Ak. d. Wiss. 92. Dec. 1885. 



2) Andrews. Proc. Roy. Soc. 42 p. 459, 1887; 44 p. 152, 1888. 



^) E. L. Nichols and W. S. Franklin. Am. Journ. of Science 31 p. 272. 1886; 

 34 p. 419, ]887; 35 p. 290, 1888. 

 4) H. A. Rowland and L. Bell. Am. Journ. of Science. 36 p. 39, 1888. 

 6) G. 0. SquiER. Am. Journ. of Science. 45 p. 443, 1893. 



