INFLUENCE OF OCCLUDED HYDROGEN ON THE 

 ELECTRICAL RESISTANCE OF PALLADIUM. 



By W. E. McElfresh. 



Presented by E. H. Hall, June 17, 1903. Receiyed November 13, 1903. 



It was observed by Graham,* in 1869, and later by D6war,t Knott, J 

 and others, that the electrical resistance of a palladium wire is much 

 greater when the wire is charged with hydrogen than when it is in its 

 normal state. 



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Proportional Increase of Mass 



I.OOI 1.002 1.003 1.004 1.005 1.006 



Figure 1. 



Knott made a quantitative study of the phenomenon, charging a wire 

 step by step and measuring its resistance after each charging. The 

 curve plotted from these results is reproduced here (Fig. 1) and chal- 

 lenges attention immediately in regard to one or two particulars. For 

 it is practically a straight line for all points between 175 volumes 

 absorbed (0.0014 increase in mass of wire) and saturation (nearly 900 



* Poggendorff's Annalen, 136 (1809). 



t Trans. Roy. Soc. Edin., Vol. 27. 



} Proc. Roy. Soc. Edin., Vol. 12 (1882-1883). 



