( 89 ) 



Physics. — - ''Researches on llw thermic and electric conductivity 

 power of crystallised conductors." I. By Dr. F. M. Jaeger. 

 (Communicated by Prof. H. A. Lorentz). 



(Communicated in llie niecllng of May 20, 19ÜG). 



1. Of late years, it lias been attempted from various sides to 

 find, by theoretical means, a connection between tiie piienomena of 

 tlie thermic and electric conductivity of metallic conductors, and this 

 with the aid of the more and more advancing electron theory. 



In 1900 papers were published successively by P. Drude ^), J. J. 

 Thomson ^) and E. Riecke ") and last year by H. A. Lorentz '). 



One of the remarkable results of these researches is this, that 

 the said theory has brought to light tJiat the quotient of the electric 

 and thermic conductivity power of all metals, independent of their 

 particular chemical nature, is a cimstant, directly proportional to the 

 absolute temperature. 



When w^e assume that the electrons in such a metal can move 

 freely with a \elocity depending on the teniperatui-e, such as happens 

 with the molecules in ideal gases and also that these electrons 

 only strike against the much heavier metallic atoms, so that in other 

 words, their mutual collision is neglected, whilst both kinds of 

 particles are considered as perfectly elastic globes, the quotient 

 of the thermic conductivity power ). and the electric conductivity 

 power a may be indeed represented by a constant, proportional to 

 the absolute temperatui-e T. 



The theories of Drude and Lorentz only differ as to the ab- 



;. 4 fa\ 



solute value of the quotient; according to Drude -= -| - T; 



Ö 3 \e J 



;. 8 fct\\^ 



according to Lorentz - = - 7'. In these expressions )., o and 



r) 9 \ej 



T have the above cited meaning, whilst a is a constant and e 



represents the electric charge of the electron. 



By means of a method originated by Kohlrausch, Jaeger and 



Diesselhorst have determined experimentally the values for - with 



ij P. DauDE, Ann. Phys. (1900). 1. 566; 3. 369. 



2, J. J. Tho-mson, Piappoit du Congres de physique Paris (1900). 3. 138. 

 S) E. Riecke, Ann. Phys. Cliem. (1898). 66. 353, 545, 1199; Ann. Phys. (1900). 

 2. 835. 



^) H. A. Lorentz, Proc. 1905, Vol. Vil, p. 438, 585, 084. 



