84 



Mr. J. Brown. [June 16, 



of contact of tlie bowls to receive this. The bowls were covered 

 by a porcelain lid. The cell in this form gave a deflexion on the 

 electrometer of 43 divisions. It was then subjected to the following 

 consecutive tests. The entries are to be read consecutively from left 

 to right, the first observation in the second column being immediately 

 subsequent to the last observation in the first column, and so on. 

 " Short circuited " means that the current of the cell was passed 

 through a low resistance astatic galvanoscope, sending the needle to 

 the stops ; " reversed " means that a nearly equal current, from a 

 Daniell cell, was sent in the opposite direction through the cell under 

 examination and the galvanoscope. After the duration of either of 

 these currents for the times given below, the force of the cell was 

 again measured on the electrometer, with the results stated : 



Zinc ZnCl 2 | SnOla | Tin. 



A similarly arranged zinc-lead cell gave, when set up, a deflection 

 of 22, and then the following deflections were noted, immediately 

 after the cell had been either short circuited, reversed, or rested on 

 open circuit, for a period of four minutes in each case, except the 

 first two observations, which were for one minute each. 



Zinc | ZnCl 2 | PbCl 2 | Lead. 



Zinc-silver and zinc-copper cells were tested in the form adopted 

 for the general investigation. The silver chloride was in the tube B, 

 fig. 1, with an asbestos plug 3 cm. long, to prevent mixing of the 

 chlorides in the separate tubes during the experiment. The copper 

 chloride was in a similar tube, corked to exclude air. The durations of 

 short circuit, rest, and reversal were each four minutes, except in the 

 second and third observations with the zinc-copper cell, in which 

 they were each one minute. 



