ELECTRICAL PROPERTIES OF HYDROGENISED PALLADIUM. 



177 



where 6 is the temperature measured in degrees of the centigrade scale — the 

 zero of temperature reckoning being the temperature at which E' is the 

 resistance. In the earlier experiments this zero of reckoning is the centigrade 

 zero ; in the later experiments 33° and 68° C. 



Comparison of Temperature Coefficients for different Specimens of Hydrogenium. 



Earlier Series. 





Later Series. 





0°C. 



33 



°C. 68° 



C. 



R'/R 



a'/a 



R'/R 



a'/a 



R'/R 



a'/a 



1-06 



1-09 











1-08 



1-06 



1-07 



1-03 



1-08 



i-'io 



1-14 



1-02 



1-13 



•97 



1-13 



•97 



1-17 



1-00 



1-26 



•82 



1-24 



•93 



1-39 





1-39 



•79 







1-47 



"■72 



1-48 



•67 



1-44 



'•76 



1-56 



•76 



1-6 



•64 



1-55 



•69 



1-78 



•50 











The most curious point established in these experiments seems to be that, 

 to a fair approximation, the total change of resistance in a given palladium 

 wire charged with hydrogen, due to a given change of temperature, is inde- 

 pendent of the amount of hydrogen present. Thus, if we form the product 

 of each pair of corresponding ratios in the table just given, we shall obtain 

 for each column a series of values differing in no case from their mean 

 by more than 6 or 8 per cent., with the single exception of the last pair 

 in the first column. These means are respectively 111, 107, and 1*12. It 

 is not unity, so that the pure palladium does not quite fall in with the hydro- 

 geniums. 



Another mode of expressing the fact here indicated is to say that, at any 

 temperature below 150° C, the increase in resistance of a given palladium wire 

 is a function simply of the amount of hydrogen taken in. This mode of regard- 

 ing the phenomenon suggested the inquiry, Does the rate of in-take of hydro- 

 gen, or the total amount that can be absorbed, depend upon the temperature 

 of the electrolyte ? A direct experiment was tried by connecting two electro- 

 lytic cells in series with the source of current, and using, as negative electrodes 

 in these cells, two equal portions of the same palladium wire. The liquid in 

 the one cell was kept at a steady temperature of 90° C, while the other was at 

 the ordinary temperature of the room, about 18° C. No difference, however, 

 in the rates of charging, or in the final charge, was observed. . 



The peculiarity in the change of resistance above 150° C, and below the 

 temperature at which loss of hydrogen sets in, is reserved for a further dis- 

 cussion ; that is, if further experiments reveal anything new. The nature of 



