| ae 
| a 
| 7 Platinum silver gold lead 
See kon he | Ob ee Gn Pe ca 
| nn > as = = = = | — === 
37986 1 365 | 1.405 1.401 | 1.411 | 1.397 1.384 | 
ese Me OF i i ee ol te Ik ff 4 i, 
169.29 0.617 | 0.579 0.581 | 583 | 0.581 | 0.586 | 0.593 | 0.601 | 0.594 
TOS eee 2a Or 213.| 0.199) | 02220") 0.197 | 0-225 | 0.219") 0,250 | 05253 
13.88 | 0.054 | 0.003 | 0.010 | 
0. 
0. 
20.18 | 0.074 | 0.012 0.014 | 0.015 0.009 0.018 0.008 0.035 | 0.030 
0.004 | 0.007 | 0.005 | 0.003 | 0.015 | 0.012 | 
0. 
4.30 0.016 0.000 [0.009] 0.000 0.000 [0.002] 0.000 
ver, it would have to be shown that the ratio of heat conductivity _* 
to electrical conductivity at hydrogen temperatures ') satisfies the 
conditions imposed by Ruiecks’s modified theory ®. 
At all events in developing new theoretical considerations it seems 
desirable to take into account the result obtained *). 
I gratefully record my indebtedness to Dr. C. Dorsman for his 
intelligent assistance during the whole of this investigation, and to 
Mr. G. Horsr, who conducted the measurements with the W urar- 
STONE-bridee with much care. 
been omitted. The influence of admixture is such as lo give rise lo impediments 
distributed, at distances determined by the quantity of admixture present, throaghout 
the metal, which exert an influence upon the mean free path of the free electrons, 
that is propertional to kT and therefore an influence on the resistance that is 
independent of the temperature just as mixed crystals do in alloys. 
Estimating for mercury a 30 on account of its lower melting-point, we get 
the following multiples of the value extrapolated to 0° C. from observations on 
the solid state (loc. cit ). 
Leids Kk. 209,8 K. 139,88 K. 
calculated 0,263 0,050 0,027 
observed 0,264 0,056 0,033 
!) Experiments to elucidate this point have been in preparation for some time. 
*) An assumption that may obviously be made is that the energy of the vibra- 
tors determines the increase of volume from the absolute zero, with which the 
explanation of the relation between expansion and change of resistance on one 
hand, and between expansion coefficient and specifie heat on the other hand, deserves 
to find a place in the theory. 
“) The further question calls for attention that is suggested by it regarding the 
peculiarities of the motion of electrons through conductors when, by taking all 
precautions, the mean free paths are as large as must, in the meantime, be assumed that 
they can be made (and begin to be comparable with the thickness of very thin layers). 
