NA TURE 



{Oct. 1 6, i! 



come. Much more may be hoped for in this direction 

 as experience increases, and it is not extravagant to hope 

 that a well-ribbed, properly-clamped, and fairly-treated 

 thick plate may last as long as five years before it becomes 

 disintegrated. 



It is evident, however, that in a region where pure ex- 

 periment is pre-eminent, and where the units of time are 

 months and years, instead of hours and days, the accumu- 

 lation of experience is a slow and tedious process. It is no 

 use making statements involving periods of five years when 

 no one has had the present improved form in use for so 

 much as six months. Nevertheless it is possible to see 

 that the present cells are better than their predecessors ; 

 and as their predecessors have lasted in good condition for 

 a year and more it is not presumptuous to indulge in 

 well-founded hopes. Many of the difficulties connected 

 with the early forms of battery were aggravated by Utopian 

 notions concerning internal resistance and compactness. 

 The internal resistance of a cell was so beautifully small, 

 that the manufacturers were tempted to diminish it still 

 further by putting the plates far too close together. An 

 eighth or tenth of an inch interval is well enough if the 

 plates had been hard rigid slabs of perfect flatness ; but it 

 was madness to pack flexible lead plates full of composition 

 certain to swell and liable to drop out so near together as 

 this. Security and dependableness were sacrificed to a 

 natural desire for sudden and Utopian perfection. We 

 may hope that these lessons have been profited by, and that 

 the manufacturers perceive that confidence and security 

 are the first conditions of success, and that minutiae as to 

 the number of noughts before the significant figures in the 

 specification of resistance begin, though those also are of 

 importance in their turn, are yet of quite secondary con- 

 sideration. Moreover, this packing of the plates so closely 

 did not really do much to secure the result desired ; the 

 greater part of the resistance of half run-down cells is not 

 in the liquid between the plates, but in the surface or scum 

 separating each plate, and especially each negative plate, 

 from the liquid, and hence putting the plates a safe distance, 

 say a quarter or one-third of an inch, apart exerts an effect 

 on the total resistance which is certainly far more than com- 

 pensated by the ready opportunity thus afforded for access 

 by both sight and touch. The old opaque boxes chock full 

 of plates, with slight india-rubber bands between them, 

 were started and left to Providence. No one could see 

 what went on, nor could one readily get at anything 

 to rectify what was wrong. In the present glass boxes 

 properly arranged on accessible shelves with only plugs 

 or studs between the plates, clear vision through the cell 

 in any direction is easy, and accidental obstruction not 

 only very seldom occurs but if it does it can without diffi- 

 culty be seen and removed. But it must be granted that 

 these boxes are less compact than their predecessors, and 

 for some purposes, such as locomotion, compactness is of 

 the first importance. Most true, for some purposes. It is 

 not to be supposed that one type of cell will answer every 

 possible demand. A dynamo to be highly efficient must 

 have a large and massive field magnet, but in some places 

 bulk and weight are fatal objections, and in these places 

 smaller and more compact dynamos may be more suit- 

 able : something, however, must be given up to secure the 

 required lightness and compactness, some sort of com- 

 promise must be effected. Just so with cells : we can point 

 out what is theoretically the best form, and this form may, 

 for large stationary electric light or power installation, be 

 actually the most suitable ; but we may also see that for 

 boats, for tramcars, and for fish torpedoes, some very 

 different and far more compact form may be quite 

 essential. 



Efficiency, Durability, Economy, Compactness : it may 

 not be possible to attain all these at once — if it were, there 

 would be small room for discussion — but sometimes one 

 and sometimes another will be the pressing necessity, and 



manufacturers of storage batteries, like manufacturers of 

 dynamos, must be prepared with forms suited to various 

 needs. 



We have spoken mainly of difficulties connected with 

 the positive plates, and have said nothing concerning the 

 negatives. It is not that these are not susceptible of im- 

 provement, but their faults have been of a less imperious 

 and obtrusive nature. They are not perfect, but they do 

 fairly well, and there has been little need to worry much 

 about them, until the extraordinary behaviour of positives 

 had been taken in hand and checked. The time is coming 

 to attend to these also. They fail not from exuberance, 

 but from inertness. As they grow old, they do not swell, 

 and warp, and burst, and crumble, like the positives, but 

 they grow quietly hoary, and serenely decay. The com- 

 position in a worn-out negative consists of white sul- 

 phate through and through, but the frame remains 

 intact, and it consequently never falls to pieces, nor does 

 it swell. Impurities in the acid used tell upon a nega- 

 tive plate — nitric acid is fatal. Acid much too weak or 

 very much too strong is also deleterious, and idleness is 

 bad. The difficulties connected with negatives mostly 

 depend on their aggravating property of always requiring 

 a quite opposite treatment to positives. The less a posi- 

 tive is formed and overcharged the better. A negative 

 delights in complete formation and frequent overcharge. 

 In recognition of this it is now customary to form them 

 separately, and to give the negative a thorough dose of 

 hydrogen without commencing the corrosion of the positive 

 by an overdose of oxygen. When the discharge from a 

 cell begins to flag, it is the resisting scum of sulphate that 

 has formed over the negative plate which is responsible 

 for the flagging. The true E.M.F. of a cell is wonder- 

 fully constant throughout the whole discharge ; but the 

 internal resistance is all the time increasing, at first very 

 slowly, ultimately, towards the end, with a rush. One 

 such run-down cell in the midst of a lot of others therefore 

 obstructs the current terribly. If only a series of cells 

 could with certainty be made to work together uniformly, 

 if a series could behave as well as some of the cells in it, 

 no one would have cause to complain. 



Through the whole history of the manufacture, from 

 the very beginning, a few cells here and there have 

 always exhibited astonishing efficiency ; — the aim of manu- 

 facturers may be said to be to bring all cells up to the 

 level of a kw. Much progress in this direction has been 

 made, and it may be very fairly expected that, as uni- 

 formity is gradually attained, a series of cells subjected to 

 the same treatment may behave in the same manner. 

 Whenever this is certainly accomplished, there will have 

 been reached a high stage of efficiency, beyond which 

 further progress need be only in the improvement of 

 comparably insignificant minutias. 



The subject of the electrical storage of energy is really 

 one of national importance ; — it is comparatively a small 

 matter whether this or that form of storage, or this or 

 that company of manufacturers, succeeds in bringing out 

 the permanent form. It sometimes unfortunately happens 

 that enterprising pioneers only clear the way, and retire 

 just in time for other men to come in and reap the fruits 

 of their labours. So much capital and so much labour have 

 been already expended in the effort to bring storage bat- 

 teries to perfection, so great progress has been made, and 

 so apparently small are the steps which yet remain to be 

 accomplished, that we may surely fairly hope that some 

 of the original believers in their great, and as it seems to 

 us inevitable, future may yet live to see their faith justified 

 and their patience rewarded, and may even taste some of 

 that so-called " substantial " reward without the hope of 

 which great commercial enterprises would never be un- 

 dertaken, and modern civilisation would have scarcely 

 yet begun. 



O. J. L. 



