1880.] The Chloride of Silver Battery. 571 



a tangent galvanometer being inserted in the circuit between the 

 battery and the voltameter, the shunt being used with the Thom- 

 son galvanometer. 



Current Deflection of Thomson 



indicated by galvanometer, with 



No. of cells. the tangent shunt g-i-g, on pressing Divisions, 

 galvanometer. down e andy. 

 W. 



1 .... 0-00000 .... 220x995-3* .... 218,930 



2 .... 0-00415 .... 765 „ .... 761,380 



3 .... 0-03463 .... 984 „ .... 978,820 

 10 .... 0-14660 990 „ .... 985,150 



On keeping down the keys e and / after the voltameter had been 

 connected with three cells, the deflection, which at first was 984 

 divisions, fell in — 



1 minute to 110 



2 minutes to 80 



3 „ 68 



4 „ 60 



5 „ 55 



6 „ 52 



7 ,, 49 



so that it was evident that a current was kept up by the voltameter 

 for a considerable time after the battery had been disconnected. 



In order to render evident the direction of the current of polarisa- 

 tion of the voltameter the apparatus was arranged as in fig. 7, that is, 

 the Thomson galvanometer, with ¥ ig- shunt, was inserted in the circuit 

 between the battery and the voltameter. An adjustable shunt was 

 fixed between a and b to permit the greater part of the current to pass 

 through it. A plate of metal, ss, was provided to slip under e and / 

 to short circuit the return current through the galvanometer. The 

 shunt which was found just sufficient to carry the major part of the 

 current, and yet permit sufficient to traverse the voltameter to produce 

 a just visible evolution of gas, was 13 ohms. 



On connecting the battery, the current was in the direction of the 

 lower arrow, and the deviation 133 divisions say to the left ; on press- 

 ing down the keys on to the metal slip placed under them to short 

 circuit the current, after the battery had been disconnected, the return 

 current was in the reverse direction, as shown by the upper dotted 

 arrow, the deviation being 425 divisions to the right. Even without 

 pressing down the keys on to the metal slip nearly the same devia- 

 tion was obtained on disconnecting battery for the return current 

 •then traversed the shunt from a to b. 



* The value of the shunt. 



