Equipotential Carves and Surfaces ; fyc. 11 



0139 



•0143 



•0142 



0136 



•0143 



•0143 



0137 



•0145 



•0142 



0141 



•0146 



•0141 



■0143 



•0143 



•0138 



The highest numbers are the values for points which are nearest to the 

 side of the box. The battery-electrodes are 100 millims. apart, and equally- 

 distant from the centre of the box. The curve is drawn through the point 

 (180, 15). 



Plate 1. fig. 11 also contains another curve for sulphate of zinc, 

 where the electrodes only just dip into the liquid, the battery-electrodes, 

 as before, being 100 millims. apart and equidistant from the centre of 

 the box. The curve is drawn through the point (170, 15). Taking the 

 40 points which have been determined experimentally for this curve, 



the values of ( - — - J are contained in the following table, arranged in 



columns : — 









•0080 



•0082 



•0083 



•0079 



•0080 



•0081 



•0083 



•0078 



•0078 



•0081 



•0082 



•0078 



•0078 



•0081 



•0080 



•0078 



•0079 



•0081 



•0081 



•0076 



•0079 



•0081 



•0081 



•0077 



•0079 



•0081 



•0080 



•0076 



•0080 



•0081 



•0079 



•0076 



•0081 



•0082 



•0079 



•0074 



•0082 



•0083 



•0079 



•0074 



The last points taken on the curve are nearer to the side and also to 

 the end of the box than to the nearest electrode ; hence for these points 

 corrections should be applied depending on the changes of potential due 

 to the side and eud of the box. 



It also appears very clearly from this series of values that, by re- 

 versing the battery-current at each observation, the polarization of the 

 galvanometer-electrodes may be kept small and very nearly constant 

 throughout a long series of experiments. 



Experiments with Linear Electrodes. 

 Case 10. The rectangular box was also employed to determine the forms 

 of the cylindrical equipotential surfaces when the electrodes are straight 

 rods and extend throughout the depth of the liquid. Sulphate of zinc was 

 employed for these experiments, and the electrodes were amalgamated 

 zinc rods. Plate 2. fig. 12 represents the sections of the equipotential 

 surfaces when one battery-electrode is at A, the centre of the box, and 

 the other at B, the middle point of one side. 



