T. Deighton 



215 



copper wire were buried therein at the 11" level. The rest of the beaker 

 was filled with the same saud very shghtly damped so as to have a 

 resistance of about 11,000 ohms between the main electrodes, consisting 

 of solder spheres on the ends of thick copper wires, placed 2^" apart in 

 the sand at the 3|" level. The subsidiary electrodes were connected to 

 a ring conductor surrounding the apparatus and this was joined through 

 a galvanometer to a single dry cell the other terminal of which made 

 connection with the wire from the metal plate at the bottom. The main 

 electrodes were connected through the bridge to the secondary of the 

 induction coil. The sensibility of the galvanometer was such that when 



Fig. 2. Apparatus and connections in Beaker Experiment. 



one subsidiary electrode was placed in conducting connection with the 

 metal plate the needle moved only a fraction of the distance across the 

 scale, so that all five electrodes would have to be in use to give anything 

 like a complete cross swing. 



Hence on pouring a solution of an electrolyte (very dilute hydrochloric 

 acid) down the funnel, it was possible to see if the surface of the 

 solution rising by capillary attraction was sensibly plane or whether it 

 was depressed or humped up at the centre; the condition for a plane 

 surface being that a sudden complete cross swing of the galvanometer 

 needle should be observed at the moment the water line visible on the 



