[reilley] CONTACT RESISTANCE OF METALS AND ALLOYS 131 



atmosphere. A surface film was formed slowly by the oil and the 

 occluded air of the contact wires. And lastly, the most conclusive 

 evidence supporting this explanation of the contact resistance is 

 the fact that by passing a larger current through the wires in the oil 

 bath, when the film has "thickened," both the contact pressure and 

 the resistance are reduced to values obtained when first observations 

 were made. 



