Hackett and Fkely — The Polarisation of a Leclanche Cell. 285 



rapid opening and closing of the cell circuit does not produce any appreciable 

 effect on the polarisation when it has reached its approximate steady value. 



After this adjustment had been made the cell circuit was opened ; the 

 deflections of the galvanometer measured the change in the E.M.F. of the cell 

 from its initial value just after opening the circuit. This method eliminates 

 any initial error, and the motion of the pointer recorded with sufficient 



20 



IS 



m 



10 



15 



43-6 



i!>Q. 



JO 



10 20 30 40 50 



Time (seconds). 



Fig. 3. 



60 



70 



80 



90 



accuracy the changes in E.M.F. if they are not too rapid. A sensible error 

 due to this cause can easily be recognized in the observations, but there was 

 no positive evidence of it. 



The observations taken in this way for the recovery of a Leclanche cell 

 polarised by a current of 0035 ampere are plotted in fig. 3, 



