78 PROCEEDINGS OF THE AMERICAN ACADEMY. 



indeed compared with the number of the atoms, the transfer of a very 

 slight proportion of these electrons from one part to another of a 

 detached wire would make a notable difference in the state of electric 

 charge and affect greatly the value of F and /. 



It is to be noted, also, that the occurrence of a great or small electric 

 concentration, n, at any place in a metal does not imply a proportional 

 state of charge there; for the electrons, in merely getting free from the 

 atoms of the metal, do not change the general condition of charge in 

 their neighborhood. The positive charges remaining on the deserted 

 atoms adjacent are still effective. 



(1) If the gas pressure tendency is toward n\R\T\= n^R 2 T 2 : — 

 In this case equation (6) holds, and we can form at once a table of 

 values of (/ -f- jS) corresponding to chosen values of q. 



TABLE I. 



Cases in which Equation (6) Holds. 

 q Rn (/"J~/3) (Virtual volts per degree C.) 17 



1 7 The values given in the last column are found as follows : 



Charge of electron = approx. 159 X10~ 22 electro-mag. units. 



Force, in dynes, acting on 1 electron in a potential gradient of 1 volt per cm. 



= 159X10^ 2 X10 8 = 159X1(T 14 2 

 Value of R for 1 molecule of an ordinary gas = 137XlO -18 ; 



" " " 1 electron = 137Xl(T 18 Xr, 



r being some quantity less than 1. Farther on some more definite estimate 

 of the value of r will be attempted. 



(Volts per cm.) /-5- (159 X 10~ 14 ) 



(Degrees " " ) = 



The variation of electric charge which one might conceivably find along the 

 wire, by means, for example, of a sufficiently sensitive pith-ball electroscope, 

 might be very different from the "virtual potential gradient"; for it is to be 

 remembered that / may be due in part to the specific attraction of the metal 

 for the electrons, this attraction acting as a function of temperature, and it is 

 probable that such action would not be perceptible at any workable distance 

 outside the metal. 



