164 



hv 

 Time bot\vo(Mi two sur-fossive omissions =J e 



L;u'mor'° in an expansion and generalization of ideas implied in Planck's 

 theory divides a system which is a seat of cnerg}- into elementary receptacles 

 of energy called "cells." The "element of <listurbance" possessing the ele- 

 ment of energy under consideration is as likely in its travels to occupy any 

 one of these cells as any other. Instead of the relation f = hv(,, which Planck 

 obtains, Laimor finds that the ratio of the energj'-clemcnt to the extent of 

 his standard cell is an absolute physical quantity. Larmor claims that his 

 theory evades an atomic constitution of energy although this seems to be 

 open to argument. Planck believes that his constant h provides for Larmor's 

 "elements of disturbance." Larmor's radiation formula reduces to that of 

 Planck. 



Jeans" has worked out a rather complete and satisfactory' electron theory 

 of metals, but when applied to radiation his results, expressed in terms of a 

 single universal constant, are in conflict with experiment. Planck considers 

 that Jeans' formula recjuires a second universal constant which he identifies 

 with h, the "wirkungs-quantum," Jeans' formula being a special case where 

 h = 0. 



Let us now (urn to some of the experimental facts which can be accoimted 

 for on the basis of the quantum hypothesis. The agreement with the experi- 

 mental facts of radiation has already been mentioned. 



The experimentally determined specific heats of crystalline substances, 

 especially at low temperatiu'es, do not agree with the older theories, but 

 Einstein'- by applying the quantum hypothesis to this case has deduced the 



formulae = 311 S , where I? is the gas constant. ^ a positixc con- 



le^ J 



stant, and v and T as before, are the \ibiatioii frecjucncy nnd I lie ;il)s(ilute 

 t('m])erature. Xeriist .and Magnus liave found that this formulnis only ap- 

 proximate and have lulded a lerni h'i ' ='■'. Tliis roiinula ;igrees with the results 



'»Roy. Soc. Proc, Sor. A, 8;i, pp. >S2-n.i, lilOi). 

 "Phil. Mag., 17, pp. 773-704, 100;); ibid IS, pp. 200-220, 100,1. 

 ".\nn. ilcr Pliysik, 22, 1, pp. ISO-100, 1000. 

 "Jaurn. do Pliy.s., 0, pp. 721-740, 1010; Zeitsclir. KIc I ro/licin., 17, pp. 20.V 27,"), I'.'ll; Ann. dor 

 Pliysik, :W. 2, pp. ;iO,5-4:!0, 1011. 



