﻿742 



Mr. R. G. Lunnon on the Unilateral 



than a dozen years ago. The bearing of this theory upon 

 Chemistry and other branches of Natural Science has already 

 been pointed out *. Suffice it to say here that the solvate 

 theory of solution is not at all at variance with the theory of 

 electrolytic dissociation, but beautifully supplements it. 



Johns Hopkins University, 1911. 



LXX. The Unilateral Conductivity of Sidphated Accumulator 

 Plates. By Robert G. Lunnon, B.Sc.\ 



THE high electrical resistance of accumulator plates 

 which have been left unused for a considerable time is 

 well known, and is due to the presence of a film of a sulphate 

 of lead on the negative plate. This resistance becomes 

 normal on the application of a high potential for a few 

 minutes, and the experiments to be described were carried 

 out to investigate this change. This object was attained, and 

 it was further found that the layer of sulphate exhibits the 

 property of aluminium anode-films in having a resistance 

 dependent upon the direction of the current. 



The accumulators used were of the simplest Plante type, 

 as used in large numbers for obtaining a high potential. A 

 different plate was necessarily used for each experiment, but 

 the properties of the cells in one tray were found to be 

 sufficiently identical to make this of no consequence. The 

 connexion between the rate of decrease of the resistance and 

 the applied potential difference was examined by including 



Lamt. 



Fig. 1. 



Ammete/r. 



E 



'IIOvocA. ST?HS05T/»T 



J 



L> 



LTM6.T6-R. 



the cell in a circuit, as shown in fig. 1. With this arrange- 

 ment, any desired p.d. could be initially applied to the cell, 

 and its diminution with time, together with the current going 



* Zeitschr. phys. Chem. lxxiv. p. 377 (1910). Journ. d. Chim. phys. 

 ix. p. 217 (193 1). Amer. Chem. Journ. xlv. p. 146 (1911). 

 t Communicated by Prof. F. T. Trouton, F.R.S. 



