- , - E:,H UV 

 V. — V, z= -'- . , . E^H . ' . J.U.=:'- .J 



10« . 10^ ^ 110 



0,89.1010. — : . 373.10-1* =3,6 



101 10-^ 



These calculations are sufficient to show that this difference of 

 potential is of the same orrler of magnitude as the HALL-eftect. 



If the electrodes are placed in little vessels communicating through 

 long tubes with the points on the axis of Z^ as frequently occurred 

 in the experiments, then no difference of concentration exists at the 

 electrodes, and the last mentioned difference of potential disappears. 



4. Comparison of theory and experiments. 



For tliis comparison we choose the experiments of Bagard with 

 a half normal solution of sulphate of copper. We find for this 

 solution V— U= 11.10-1=^ ^). 



The experiments of Bagard however in a fielii of 385 C. G. S. 



E- 

 give for —;-:// a value of 13.10~'. 

 Ex 



Taking the sixteenth normal solution in the strongest field, 962, 

 the theory gives 14.10— i^, the experiment 35.10—'^. 



If we moreover consider, that even the sign of the apparent effect, 

 which agrees here with the theoretical sign, in the experiments of 

 Chiavassa with sulphate of zinc proved to be variable, it will 

 appear that we may safely conclude that the hitherto observed 

 galvano-magnetic differences of potential in liquids are not caused 

 by the pheuomenon of Hall. 



Researches much more accurate than have been attempted till now -) 

 should decide whether the weak theoretical effect can be observed. 

 It may be doubted however whether the disturbances, which can 

 assume such large proportions, will ever be completely avoided. 



5. So the result of this research is: for the present we can not 



1) In the dissertation the factor 1U~^ (ratio of volt mid C.G.S. unit) has been 

 uni'tted. As moreover the accurate researches of Chiavassa had not yet appeared 

 then, the experiments of Bagakd were, at that time, trusted more than they now 

 appear to deserve. Also mr. F. (i. D"NNan at llolywood (Ireland) has noticed the 

 omission and has been so kind as to tell me so. 



2) The smallest observable ditterence of potential was in the experiments of 

 Chiavassa 3.10""^ volts. The largest effect calculated above would give for a slope 

 of potential of 1 volt per cM in a field of 10000 C.G.S. units 1,1:.10-^ volts. 



