( ,S2 ) 



This result does not appear to me very probable. 



6. I wish to defer a comparison between theory and experiments 

 entering into more particulars until also the longitudinal pheno- 

 mena: the conductivity for electricity and for heat, the change of 

 these in the magnetic field and the longitudinal thermomagnetic 

 effect have been investigated in this plate. 



I think it probable that Riecke's theory will have to be modified. 

 Firstly also the variation in the magnetic field of the conductivity 

 for electricity and heat might be included in it. The observations 

 of these phenomena prove that the variation is much smaller for the 

 thermal conductivity than for the electrical conductivity. This indi- 

 cates, I think, that the theory wrongly ascribes the whole conduc- 

 tion of heat to the charged particles ^). It would be desirable to 

 try whether it is possible, taking this into account, to explain the 

 phenomena with the assumption that the kinetic energy is the same 

 for positive and negative charged particles, which seems at first 

 sight more probable. At the same time it might perhaps be recom- 

 mended to omit, in the deduction of the formulae for the four trans- 

 verse phenomena, the condition that the velocities of the particles 

 in the direction of the electromagnetic force should be zero, and to 

 replace it by a similar condition as was assumed by me in the 

 theory of the HALL-effect in electrolytes ^). Finally it will appear 

 necessary to make some hypothesis in reply to the question, what 

 happens with the charged particles when they reach the borders of 

 the metal Riecke himself indeed has observed ^), that it is not 

 possible to formulate a complete theory of thermo-electricity with 

 the aid of his hypotheses whithout accounting for the conditions at 

 the junction of the two metals and forming an idea about the reci- 

 procal influence of ponderable molecules and electric particles. 



Physics. — Oh the deviution of de Heen's experiments from van 

 DER Waals' law of continuity. By Dr. J. Verschaffelt 

 (Communicated by Prof. H. Kamerlingh Onnes). 



(Will be published in the Proceedings of the next meeting). 



1) See my dissertation p. 114. 



') See communicatioE of May 28, 181)8, p. 48. Comm. N". 41, p. 6. 



*) § 8 of liis paper. 



