( 404 ) 



so tbat the corrected equation of yax der Waa.ls would liave the 

 following form 



a (-1 h h b^ /1283 3 /?\ bh 



'6 U'' ( 957 3 /y\ b^ 



v — bA 1- -\ - 



' 8 ü \89ü0 2 / »■■' 



In tliis formula is accordiu!? to Mr. van Laar 



(12) 



3i/'2 + 81.17 {arctg\/1 — ^) 



ft = ■ = o.oor.s 



' 32.85 .T 



Physics. — ^ Tlir (jdlcano-mafjnetic and ihcrmo-mafinetic phenomena 

 in hisniuth". (Second Communication.) By Dr. E. van Ever- 

 DiNGEN Jr. (Communication W. 48 from the Physical Laho- 

 ratory at Leiden, by Prof. H. Kamerling h Onnes.) 



L Li the Proceedings of the meeting of June 25"' 1808 we 

 have communicated the results of the observations of the four trans- 

 verse galvano-magnetio and thermo-magnetic phenomena, all of 

 them made in one and the same magnetic field with one and the 

 same eloctrolytically prepared plate of bismuth. By means of the 

 same plate of bismuth we have now observed the decrease of con- 

 ductivity for electricity and heat and also the longitudinal tbcrmo- 

 magnctie phenomenon. It has given us much trouble to measure the 

 two last phenomena with sufficient accuracy, and the variation of 

 the eonductivitv for heat can only approximately be deduced from 

 the measurements. Yet I communicate the results for two reasons: 

 in the first place, for a preliminary theory it is sufficient that the 

 order of magnitude of the phenomena is known, <and secondly in 

 consequence of the small dimensions of the plate it is not probable 

 that further measurements with the same plate would yield a much 

 more exact result for the absolute value. Moreover the plate during 

 one of the last experiments has developed a crack and this has 

 put an end to all further observations under the same circumstances, 

 even if we had wished to continue them. 



Those measurements having been finislicd we liave ol)taincd for 



