TRANSACTIONS OF SECTION B. 673 



2. On the Chemical Aspect of the Storage of Power. 

 By Professor E. Fkankland, D.C.L., M.D., F.B.S. 



The author has continued his experiments ou electrical accumulators, and in the 

 present paper communicates the results of a study of the phenomena attending the 

 discharge of accumulator cells containing- alternate plates of plumbic peroxide and 

 spongy lead. The storage cell employed contained ten plates with an aggregate 

 active surface of 12'3 square feet, and it was charged by a current of from 15 to 

 20 amperes generated by a Siemens' shunt machine, and was then allowed to rest 

 for three days. 



The discharge was made through a piece of platinum wire 1-035 m.m. in 

 diameter and 10 inches long. This wire was maintained at a red heat, so lono- as 

 the current did not sink below 17 amperes. The discharge occupied 73 hours iu 

 one experiment, 147i in a second, and 141 hours in a third. 



In all these experiments, moderate currents only were drawn from the cells 

 such as would be used for the supply of 14 or 15 Swan lamps of 20-candle power • 

 but very much heavier currents can be obtained if desired, even up to 250 

 amperes. 



From the results of these experiments, the author draws the followino- con- 

 clusions : 



1. The energy of a charged storage cell is delivered iu two separate portions, 

 one having an E. M. F. of 2 volts and upwards ; the other an E. M. F. of 0-5 volt 

 and under. One of these may be conveniently termed useful, and the other useless 

 electricity. 



2. The proportion of useful electricity obtainable is greatest when the cell is 

 discharged intermittently, and least when the discharge is continuous. 



3. Neither in the intermittent nor continuous discharge at high E. M. F. is the 

 current, through uniform resistance, augmented by rest. At low E. M. F. how- 

 ever, the current, after continuous discharge of the high E. M. F. portion, is f reatly aug- 

 mented, but only for a few minutes. This augmentation of current, at low E. M. F. 

 after rest, is barely perceptible when the high E. M. F. discharge has been 

 taken intermittently. 



4. The suddenness of fall in potential during discharge indicates two entirely 

 distinct chemical changes, the one resulting in an E. M. F. of about 2-5 volts the 

 other in one of about - 3 volt. 



5. The chemical change producing low E. M . F. is the first to occur in charging , 

 and the last to take place in discharging the cell. It is the change which occurs' 

 during what is called the ' formation ' of a cell, and, for economy's sake, a reversal 

 of this change should never be allowed to take place. 



6. It would not be difficult to suggest an explanation of the nature of these 

 two chemical changes, but the author refrains pending their actual investigation in 

 which he is now engaged. 



7. Currents of enormous strength can be readily obtained from storage batteries 

 coupled up in parallel. For instance, a current of 25,000 amperes is quite feasible 

 from only 100 cells. Such a current reduces to insignificance the output of the 

 largest dynamo ever built. It is to be hoped that currents of this magnitude will 

 open up new possibilities of research into the constitution of matter. 



3. On the Magnetic Rotation of Compounds in relation to their Chemical 

 Composition. By W. H. Perkin, Ph.D., F.B.S. 



The author gave a resume of his researches on the magnetic rotary polarisation 

 of compounds in relation to their chemical composition. After referring to the 

 remarkable discovery of Faraday in relation to this subject and the results°obtained 

 by more recent workers in this field, it was shown that no relationship in 

 reference to chemical composition was likely to be found by the usual method of 

 calculating the results of the observation of unit lengths of the fluid bodies 

 examined, but that if lengths related to each other in proportion to their molecular 

 weights, making the necessary correction for the difference of densities, were com- 

 1884. x x 



