1894.] Thermo-electric Properties of Salt Solutions. 369 



The solution under examination is put in C, so as to cover A to a 

 depth of half an inch, or thereabouts. 



For measuring the current, the potential between the ends of a 

 known resistance in its circuit was compared with a Clarke cell. 

 Thus, if on the potentiometer the latter = S, the former = RC being 

 T, we have 



RC = (T/S) 1-434 volt. 



For measuring the resistance, or rather the change in the resistance, 

 of the coil B, a circular wire bridge, of what is believed to be a new 

 form (fig. 7), which entirely avoids all thermoelectric disturbance, 

 was used. The bridge wire, A, is on the inside wall of a circular 

 channel, cut in a thick piece of wood. A second wire, B, made of 

 the same material as A, is sprung into a groove on the outside wall 

 of the channel. The ends of A are on two copper plates close to- 

 gether, and the ends of B are on a copper plate just opposite them, 

 on the other side of the channel, so that all the junctions of dissimilar 

 metals are within an area of about 1 sq. in. Contact is made between 



