372 Intelligence and Miscellaneous Articles. 



bismuth. Two equal plates, each 0*043 centim. thick, were placed 

 with their surfaces parallel and near each other, so that the current 

 J was divided between them. The distance o£ the plates was 

 about 1 millim., and the solderings of the thermoelement were inter- 

 posed in the space at the upper and lower edges of the plate, and 

 carefully insulated by thin laminae of mica. 



With a strength of the magnetic field M= 6400, and for J equal 

 to 1*76 amperes, for the undivided current the mean of the deflec- 

 tions of the needle was i=17*3 divisions ; for J =3*28 amperes i= 

 32-8, so that the intensity is nearly proportional to the strength of 

 the current passing through the double plate 



For M = 4290, J =3-05 amp., i = 20-3 divisions, 

 6250, 3-05 29-9 



and the action is thus also proportional to the intensity of the 

 magnetic field. 



If, instead of the galvanic current, a thermal current was passed 

 through the plate, the thermoelements interposed between the 

 plates did not show the smallest difference of temperature when the 

 magnetic field was excited in either direction. 



In order to ascertain whether the new phenomenon is seen in 

 different bismuth plates in different intensity, and especially if in 

 bismuth, which produces Hall's phenomenon in greatest strength, the 

 galvanomagnetic difference of temperature is greater, I investigated 

 a second double plate II. ; each single plate was 7 centim. in length, 

 1*9 centim. in breadth, and about 0-08 centim. in thickness : the 

 double plate I. previously mentioned was made of the same breadth 

 as II. 



I made successively experiments with each double plate and two 

 different intensities of fixed M= 4400 and 6310: for the same 

 total intensity of the current J which traverses the plate the 

 differences of temperature produced at the edges of the plates in I. 

 and II. were about in the ratio 1*92 : 1. 



The rotatory powers of the bismuth plates were very different for 

 the same M ; the bismuth of the double plate which showed the 

 greater galvanometric difference of temperature had the smaller 

 rotatory power. On the other hand, the ratio of the sections of I. 

 and II. is nearly 1 : 1*9, and hence for the same strength of 

 current, the density of the current has a preponderating influence 

 on the strength of the effects in bismuth. 



I observe in conclusion that the difference of temperature which 

 was produced by the magnetic field M = 6310 at the edges of the 

 double plate I. for the total strength of current J =4-55 amperes 

 amounted to about l°-3 C. : the electromotive force of my thermo- 

 element for a difference of 1° C. in the solderings was very 

 nearly 11 microvolts. — Berichteder Kaiserlichen Akademie in Wien, 

 January 13, 1887. 



