HALL. — CONDUCTIVITY OP SOFT IRON. 129 



and copper end-pieces has been dealt with more carefully and successfully 

 in recent experiments than iu earlier ones, and that in some cases the bars 

 have been placed in a glass tube instead of a wooden one. The results 

 of these thermo-electric tests, subject to slight corrections for pecu- 

 liarities of the thermometers* used, are given below. The temperature 

 put down for each case, in the second column, is the mean of the ther- 

 mometer readings in the two copper blocks at the ends of the row of iron 

 bars. The third column, headed A, gives for each case the mean differ- 

 ence of temperature of the two thermometers. The fourth column, headed 

 E, gives for each case the thermo-electromotive force corresponding to a 

 difference of 1° between the two thermometers, each of which thermome- 

 ters is supposed to iudicate with sufficient accuracy the temperature of 

 the copper-iron contact neighboring to it. 



.A B 



7°.0 k 1041 x 10" 8 ^ 



7°. 52J 1017 " 



7° fil I 1024 " 



>26°.6 ' "": >7°.30 "Z ,, S1028 X 10" 8 



volt 



8°. 22/ ' 1042 



6°.64\ 1031 



6 .79/ 1012 



7°.W\ 979 



7°.23/ 964 



7°.79>7°.19 982 



6°.94\ 990 



6° .57; 976 



7°.03 > \ 926 



6°. 95/ 930 



7°.60>6°.89 941 " 



6°.64\ 938 " 



6°.25j 933 " 



6°.07>. 885 " 



6°. 24 J 850 " 



,71°.l ££>.* |» I > 871X10- 



6°.04l 879 



6°.66j 870 



changed, and, except during the moments of measurement of resistance, no electric 

 current flowing through the row of bars. 



* Baudin, Nos. 10,286 and 10,287, as in previous work. 

 vol. xxxvi. — 9 



