TRANSACTIONS OF SECTION B. 



673 



:u cannot 

 ac'ni and 



the inert 



tlilVfrenl. 



viivyin^' 



1 (lill'eront 



it when a 

 ixy^i'iMi for 

 1 can take 

 .•cssure, an 

 icndont of 

 I luilf tlu' 

 ;oniiilftely 

 ;id, iiydro- 



}n, and of 

 iiartz ends, 

 jgs ot tliiu 

 sonu! caso 

 many iron 

 . iovty-niiie 

 lliau O was 

 p of cobalt, 

 '0 any thin}.; 

 ev fi;ave one 

 nhun, tlirt'e 

 ultra-violet 

 mil llio piiv 

 a, Ijisuiuth, 

 Iplmvetted, 

 no pecnlitir 

 iron, niclitl 

 5un?en and 

 nd iliis mtiy 

 rominences. 

 if the lines 

 ho iron line 

 ly come out 

 seen in tlie 

 out in the 



F.R.S. 



2. On the Chp.mical Aspect of the Slorarfe of Power. 

 Bij Professor E. Frankland, D.C.L., M.D., F.R.S. 



The author has continued his experiments on 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 st<n'age cell employed contained ten plates with tin aggregate 

 li'^tive surface of 12-y square' feet, and it was charged Ly a current of from 15 to 

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

 for three days. 



Tlie discharge was mad; through a piece of platinum wire 1'0.35 m.m. in 

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

 tla' current did not sink below 17 amperes. The discliarge occupied 73 hours in 

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



In all these txperimeiits, moderate currents oidy were drawn from the cells, 

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

 bat very much heavier currents can be obtained if de.^ired, even up to 250 

 amperes. 



From the results of these experiments, tlio autiior draws the following con- 

 clusions : 



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

 one having an E. M. V. of 2 volts and upwards ; the other an K. 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 great(;st when the cell is 

 discliarged intermittently, and least when the diseharge is continuous. 



'•'), Neither in the intermittent nor conthiuous discharge at high }]. M. F. is the 

 current, through uniform resistance, augmented by rest. At low E. M. l'\, how- 

 ever, the current, after continKousdisc/utrr/c (ff/ic lii(/h E. Af. F. jiorfion, is greatly 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 1"]. M. Y. discharge has been 

 taken intermittently. 



4. The suddenness of fall in potential during discliarge 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 0'3 volt. 



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

 and the last to tahe 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. 



0. It would not be ditlicult to suggest an explanation of the nature of these 

 two chemical changes, but the author refrains per.ding their actual investigation in 

 which he is now engaged. 



7. ( 'urrents of enormous strength can be readily obtained from storage batteries 

 cou])led up in parallel. F'or 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 liotation of Compounds in relation to their Chemical 

 Composition. By W. H. Perkin, IVlD., F.R.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 residts 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 res>dts of the observation of unit lengtiis of the fiuid bodies 

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

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



1884. ' ; ■• ' X X 



* . I. . 



m 



m. 



