the Electrical Resistance of Bismuth. 



341 



truncated cones joined together. The section of this cylinder 

 can then be taken as the mean section of the rod. 



All the absolute values that I give further on are thus only 

 approximations, but they approach very near to the true 

 values. 



Results of the Electrical Measurements. 



The following Tables contain, in column W, the electrical 

 resistances as I have measured them, that is to say in Siemens 

 units, and at different temperatures given by a Centigrade 

 thermometer. I have given also, for each bismuth, the specific 

 electrical resistance R in C.G.S. units at 0° temperature; 

 and the mean coefficient of variation of the electrical resistance 

 between 0° and 100°, i. e. the quantity K of the equation 

 R,=Bo(l + Kf). 



Bismuths. 



(1) 



Rods which have 



been slowly cooled. 







1 w. 



K. 



Variation for 

 1° between 0° and 100°. 





Bismuths. 



Tempera- 

 tures. 



Electrical 



resistances 



in U.S. 



R, 



. 



o 

 



0-1390 







Latest Bromins- J 



19 



0-1462 







dorff 1 



r 



49-1 



996 







01590 

 0-1840 

 0-2875 



+ 0-00325 



10 3 x 109-90 



Classen I \ 



191 



49-2 



0-2882 

 0-2922 



4-0-00076 





1 



1 



99-6 



0-3095 







f 







01615 







Classen II \ 



16-7 

 49-6 



0-1680 

 0-1828 



4-000299 



10 3 x 124-69 



1 



I 



995 



0-2096 







f 







0-2447 







(2) Classen III. 



20-5 



0-2500 



+0-00161 





2nd rod. 1 



r 



49-8 



99-8 







0-2595 

 0-2841 

 0-2407 







(1) Classen III. I 



20-5 



0-2439 



+0-00132 



10 3 x 156-74 



1st rod. 



49-7 

 99-8 



0-2509 

 0-2725 







/ 







20-3 

 99-8 



0-2036 

 0-2063 

 0-2302 









It is allowed to cool slowly. 







1 0-2043 







Classen IV. 

 1st rod. 



19-9 1 0-2066- 

 It is heated to 100°, 



and allowed to cool slowly. 











0-2048 









20 



0-2069 



+0-00126 



10 3 X 170-07 





52-5 



0-2136 









99-6 



0-2305 







It is allowed to cool again slowly, and it is found that the 



1 



values 



remain cons 



tant. 





