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XVIII. Notes on Secondary Batteries, By J. H. Gladstone, 

 Ph.D., F.R.S., and W. Hibbert, F.LC* 



EIGHT years ago, one of us, in conjunction with the late 

 Mr. Tribe, published a series of papers on the Chemistry 

 of Secondary Batteries f. Since that time accumulators have 

 undergone many improvements in detail, but they still present 

 some unsolved problems of a more or less subtle character. 

 In this paper we give an account of some experiments under- 

 taken to test points which have arisen in the last few years. 



A ction of Sodium Sulphate. 



In May 1889 Mr. Preece delivered a lecture at the Society 

 of Arts dealing generally with his experience of Secondary 

 Batteries Among the topics treated was the influence of 

 the composition of the electrolyte on the working of the cell, 

 and it was stated that the addition of sodium sulphate to the 

 acid solution was of very considerable advantage. Mr. Preece 

 determined the proportions of acid and sulphate which gave 

 the best result in a year's working, and found that a compa- 

 ratively small quantity of the salt was sufficient to produce 

 the effect. 



We have determined the percentage composition of the 

 liquid from a sample kindly furnished by Mr. Preece, and find 

 it to be as follows : — 



Sodium sulphate (Na 2 S0 4 ) . 0*81 

 Sulphuric acid (H 2 S0 4 ) . . 29'39 

 Water 69*80 



100-00 



The specific gravity at ordinary temperatures is about 1*23 J. 



When used in secondary batteries instead of the usual acid, 

 it is stated that there is less buckling of the plates and little or 

 no scaling. The chief benefit, however, is stated to be that 

 the sodium salt diminishes the chance of objectionable sulpha- 

 ting in the cell, and where such sulphating occurs, enables it 



* Communicated by the Physical Society : read June 20, 1890. 



t Nature, 1882 and 1883, vols. xxv. andxxvi. ; afterwards published by 

 Macmillan. 



X In making this liquid, it would be best to add together (58 parts 

 (by weight) of water, 30 of strong sulphuric acid, and 2 parts of crystal- 

 lized sodium sulphate (Na 2 S0 4 . 10H 2 O). 



