SOME COXTF.MI'OR.INV .IPr.lXClLS IX rilVSICS f M<) 



Wilson has ri'ccntl\- iu.kK- .i spfcitir assiiiuplion ri'^ardinj; tlu-sc. 

 For still further suhtli-tii-s Ikidj^nian's llu-ort'tical articles may In- 

 consulted. I must ho\ve\er add that an extension of the thermo- 

 dynamical argument, with the assistance of Nernst's "third law of 

 thermodynamics," leatls to the conclusion that the constant (' of 

 eciiiation (23) should have for all elements, if not indeed for all sub- 

 stances, the sanie universal value, calculable in terms of certain 

 universiil constants. There is some e\idence that this may he true 

 for emission from pure elements. Wire il ><i. ihi- result would he 

 of fundamental intportance; hut anotiu-r article almost as loiijf as 

 this one would be required to explain it properK'. 



The general tone and character of this article will probably lea\e 

 the final impression that the electrical beha\iour of solids is an utterly 

 confused and chaotic ilepartment of physics, a hopeless entangle- 

 ment of incongruous rules diversified by numberless exceptions. 

 I fear that this impression — except perhaps for the hopelessness of 

 the situation — is substantially the correct f)ne. In fact this pres- 

 entation has put the state of afTairs in rather too faxorable a light, 

 for I ha\e passed over a number of the perplexities. I have scarcely 

 mentioned the thermoelectric effects, or spoken of the complexities 

 of the phot(K'lectric effect, or of the emission of electrons from metals 

 which are bombarded by other electrons or by ionized atoms; and I 

 have not mentioned at all the galvanomagnetic and thermomagnetic 

 effects, the most baffling and bewildering of all. In fact it seems 

 only too probable that if one should succeed in erecting a theor\- b\- 

 which all the phenomena I have de.scribed could be brought into 

 one coherent system, some galvanomagnetic effect would be lying 

 in wait for it to bring it to the dust. Clairaut is said to have been 

 siiddcned by feeling that Newton had discovered all the laws of 

 celestial mechanics, leaving nothing for men born after him to do 

 e.xcept to improve the methods of calculation. Ambitious students 

 of physics who, through too exclusive a study of the radiations from 

 atoms, may have come to feel in the same way about Bohr, should 

 find consolation in contemplating the present status of the Theory 

 of Conduction in .Solids. 



I.ITER.VTIRK 



The chief recent loiiipilation of cl.ita upon fondiirtion in solids is KoenigslxTgcr's 

 article in (".ractz* Ilandbuch Her Eleklrizilal. K. Haeclckcr wrote an excellent snort 

 account of the data and the theories, entitled Die elektrischen Erscheinungfn in 

 melallischen Leilern, which although pul>lishe<l in lOll is not yet suiKTseded. Bid- 

 well's p;ifKT on germanium is in Phys. Rev. (2i /.">, pp. 447-45.S (1922); .Noyes' 

 article on carlwn in Phys. Rev. (2) J.',, pp. 10O-1Q9 (1924). The investigations on 

 supraconductivity are reported chiefly in the Leydrn Communications; Cromnielin 



