535 



The initial and boundary condiiions are: 



R^=A,+ B, H^ = A, 



V d^ Jx=.r 



I fdH,\ _ 1 rdJI. 



The third of the four above written lines shows that 



where « is constant. Eliminating the constants A, B from the above 

 equations the result for « is: 



(13) 



We are particularly interested in the meaning of this equation 

 for the case of a very large li,. The values of « which satisfy (13) 

 for this case must he very small because neither finite iior infinitely 

 large values of « satisfy (13) in the case of an infinite /J,. If « is 

 very small the iiunieralor of the right hand member of (13) reduces 



to '-^(J,. Therefore a must vanish at least as —=. for otherwise the 



factor e * 0| ^| will yield an infinite result. The presence of 



•//?, in the denominator of (13) assures us moreover that « vanishes 



1 _ 



to a still hielier order than ^;:=. Therefore a l^/J, is infinitesimal and 



f"ÏA\ ^ '^^ 



Hence (13) leads to: 



if i?, is very large. Thus the propagation of the boundary between 

 the two states is infinitely slow if the microresidual resistance is 

 infinitesimal. It should take an infinite time for tiie conductor to 

 become entirely supra-conducting under the conditions just considered. 



