( 2S ) 



proofs of the existence of the HALL-effect in liquids, and attributed 

 those differences rather to ponderomotive forces, exerted by the mag- 

 netic force on the particles of salt, to diiTerences of concentration 

 or to differences of temperature. The two physicists first mentioned 

 confined themselves to experiments, in which disturbances of this 

 kind were avoided, and the HALL-effect had really disappeared ; 

 Chtavassa however also demonstrated the existence of differences 

 of temperature and of concentration, determined the influence of 

 these differences on the readings of the electrometer, and proved that 

 in a non homogeneous magnetic field vortical motions occur in the 

 liquid, which depend on the strength of the current, the magnetic 

 field etc. in the same manner as the observed apparent HALL-eftect. 



Bagarü ') on the contrary believed to have avoided all distur- 

 bances in his experiments and was therefore convinced of the reality 

 of the HALL-effect in liquids. 



The observations of Chiayassa were made in the same manner 

 as those of Bagard; hence the greater part of the difference of 

 potential observed by Bagard was very liivcly due to disturbances. 

 In the controlling experiments however, which were to prove that 

 whithout disturbances no difference of potential appears at all, 

 strongly concentrated solutions were always used ; so it was still 

 possible that in the diluted solutions used by Bagard a part of the 

 observed effect would remain even in the absence of disturbances. 

 Hence the question has not yet been solved by experiment. 



3. We proceed to the theory of the phenomenon and for the 

 present confine our attention to the state of matters in the inner part 

 of the liquid, i. e. far from the lateral borders. If we put for the 

 E. M. F. in the direction of the axis of X Ex, and for the velocities 

 of the ions caused by a slope of potential of 1 C. G. S. unit per cM. 

 U and F, then the velocities are 



E:,U and E^V 



respectively in the directions of the positive and the negative axis 

 of X. We assume with Lürentz") that an ion, moving with the 

 velocity v in a magnetic field of intensity B is acted upon by a 

 force represented by the vector product [v. B.] for each unit of elec- 



') C. K. T. 123, p. 77 and 1270, 1896. Journ. de Phys. Slt. 3, T. 5, p. 499, 1896. 

 ") See f. i. Versucli einer Theorie der electrischen und optischeii Krscheimingeu 

 in bewegten Korpern. Leiden, 1895. 



