TOLMAN. — ELECTROMOTIVE FORCE PRODUCED IN SOLUTIONS. 125 



The Mercury Contacts. 



Connection between the leads, which came up through the hollow 

 shafts, and the external measuring circuit was made through the mer- 

 cury contacts C indicated in Figure 1 and shown in detail in Figure 5. 

 The leads from the electrodes were made fast to the binding posts M 

 and N, and electric connection was made through the small rotating 



Figure 5. The Mercury Contacts, i size. 



shafts G and H with mercury, which was placed in the circular troughs 

 E and F in the steel blocks W and Z. The two small shafts are insu- 

 lated from one another and from the outside driving shaft by fine 

 rubber tubing, and at the bottom by vulcanite disks. The steel blocks 

 are insulated from each other and their supports X and Y by vulca- 

 nite washers and sleeves. Connection is made from the steel blocks 

 to the measuring instruments. 



The apparatus was specially designed with the purpose of eliminat- 

 ing the production of electromotive forces at the point of contact 



