the Electrical Resistance of Bismuth. 



335 



by Prof. Righi can be partly accounted for by tbe discon- 

 tinuity of the bismuth wires. 



G. P. Grimaldi* has studied the thermoelectric pro- 

 perties of bismuth, and has confirmed the analogies which 

 Prof. Righi has found between pure bismuth and iron, the 

 bismuth containing tin and steel. 



A. von Ettingshausen and W. Nernst f have obtained 

 results which are recorded in the following Table, where x is 

 the electrical conductivity in absolute measure, and a the co- 

 efficient of variation of the electrical resistance with the tem- 

 perature. The plates denoted by Bi were made of absolutely 

 pure bismuth ; the other plates denoted by LI to LIY were 

 made of an alloy with tin. 





Bismuth. 



Tin. 



*(G.S.). 



a. 





Parts by 



Parts by 









weight. 



weight. 



4-80 xlO -6 





Bi 



100 





-00012 



LI 



99 05 



0-95 



2-46 x 10 ~ 6 



+0 0016 



LII 



98-54 



1-46 



2-71 Xl0~ 6 



+0-0018 



LIIL ... 



93-86 



6-14 



346 Xl0~ 6 



+0-0024 



LIV. ... 



869 



131 



562 X lO" 6 



+0-0025 



The electrical resistance increases then (between 0° and 

 30°) for every alloy, when the temperature is raised ; it 

 decreases on the contrary for pure bismuth under the same 

 conditions. On increasing the quantity of tin, the coefficient 

 of temperature a also increases. The conductivity decreases 

 rapidly by the addition of small quantities of tin, and increases 

 again afterwards. 



C. L. Weber J has found that the resistance of the metal 

 under consideration at first decreased up to about 100°, the 

 coefficient of temperature being — O0006 ; and then in- 

 creased up to the melting-point. The position of the mini- 

 mum, however, is displaced by repeated heatings and coolings 

 between 80° and 120°. 



The same physicist has also observed that the electrical 

 resistance of alloys of bismuth and tin, containing from 10 

 to 80 per cent, of bismuth, increases between 0° and 120°, 

 as the temperature is raised. 



* Beibldtter zu den Annalen der Physik (1889), No. 1, p. 25. 



t W. Nernst, Annalen der Physik, Neue Folge, Bd. xxxi. p. 783 

 (1887) ; A. von Ettingshausen and W. Nernst, Annalen der Physik (1888), 

 Heft iii, p. 474. 



\ Annalen der Physik, 1888, xxxiv. p. 576. 



2 B 2 



