;62 



NATURE 



[February 20, 1902 



have been carefully brought up to date. They furnish a 

 trustworthy account of the essential facts of anatomy and 

 development, but as occurs in the case of the other 

 groups described in this volume, the problem of their 

 affinities is not set forth with that clearness which is so 

 essential to its comprehension. 



Considered as a vvhole, the volume has not that illu- 

 minating and suggestive value which distinguished the 

 earlier volumes of the "Treatise." Nevertheless it will 

 remain for some time the chief work of reference in the 

 language on the anatomy and classification of the groups 

 with which it deals. 



PRIMA R y BA TTERIES. 

 Primary Batteries : their Theory, Construction and Use. 

 By W. R. Cooper. Pp. 4 + 324. (London: The 

 Electrician Printing and Publishing Co., Ltd., on 

 date.) Price \os. (id. net. 



MR. \V. R. COOPER'S book directs attention to a 

 subject which will always be of great historical 

 interest on account of the remarkable stimulus given to 

 electrical science by the discoveries of Galvani and 

 Volta. At the present time, it is true, the primary 

 battery has yielded to cheaper and more convenient 

 sources of electrical energy, and the position which 

 it holds in electrical engineering is comparatively 

 insignificant. It is not improbable that before long 

 it will be displaced from almost all practical appli- 

 cations of electricity and will only be found where 

 the dynamo and accumulator are unavailable. It may, 

 however, be some consolation to those who have not 

 other means at hand to reflect that in the research by 

 which Faraday laid down the fundamental laws of electro- 

 lysis he obtained current from a primary battery of the 

 most elementary form. The advantage of amalgamating 

 the zinc had been shown five years earlier (1828) by 

 Kemp, but it was not until 1836 that the first effective 

 depolarising cell, that of Daniell, was described ; the 

 invention of the Grove cell followed in 1S39. The 

 Leclanchc cell, which did not appear until 186S, marks 

 the only other development of the first importance. 



In spite of the fact that \'olta's discovery is more than a 

 century old, the theory of the primary battery cannot be 

 said to be in a very satisfactory state. Mr. Cooper 

 devotes two chapters to this subject, the first of which 

 deals chiefly with contact-force and the seat of the 

 E.M.F. in the cell. Mr. Cooper, in summing up the 

 various theories, states that "the whole matter (of the 

 seat of the E.M.F.) is largely a question of definition, 

 and is, therefore, of relatively small importance," a con- 

 clusion which is not likely to commend itself to those 

 who are anxious to arrive at the truth. In the second 

 chapter, the ionisation theory of Arrhenius is discussed 

 and the calculations of the E.M.F. of a cell from the 

 equations of Helmholtz and Nernst are compared, with 

 results which are not very convincing in either case. 

 The author then passes to a brief consideration of con- 

 centration and liquid cells (which are at present only of 

 theoretical interest) and of the thermopile, which, he 

 points out, on account of its high price is not likely to 

 prove a serious competitor to the primary battery. 

 There follows what may be called the practical part of 

 NO. 1686, VOL. 65] 



the book, in which the various types of existing cells are- 

 described and which contains much valuable information 

 collected or directly obtained by the author. Cells are 

 classified under three headings, one-fluid, two-fluid and 

 dry cells. In the first division, the principal examples 

 are the bichromate, Leclanchc and copper-oxide cells. 

 .Some interesting tests carried out by the author show 

 that in the bichromate cell the most suitable depolariser 

 to use is chromic acid, which gives a discharge curve 

 as good as that given by either sodium or potassium 

 bichromate and is also more convenient and as cheap 

 The two-fluid cells include the Uaniell, with its numerous 

 derivatives, and the Grove and Bunsen cells, which on 

 account of their high E.M.F. and low internal resistance 

 are especially suitable where heavy currents are required. 

 All the dry cells are modifications of the Leclanche and 

 do not differ much from one another except in details of 

 construction. It is somewhat surprising to find that, 

 weight for weight, the dry cell is superior to the wet form 

 of Leclanchc. Against this must be set the somewhat 

 higher initial cost and the advantage of the possibility of 

 regenerating an exhausted wet cell, though this latter 

 consideration, as Mr. Cooper shows, is in reality some- 

 what illusory. The usefulness of this part of the book 

 is greatly increased by the numerous discharge curves 

 which are included and by the many very clear drawings 

 illustrating the various cells described. 



The last two chapters deal with standard cells and 

 carbon-consuming batteries. The standard cell is, and is 

 likely always to remain, of the highest practical impor- 

 tance ; the chapter dealing with it is consequently of great 

 interest and value, as it contains in a convenient form 

 most of the hitherto scattered information on this subject. 

 The table of constants of standard cells shows that the 

 results of recent determinations point to the value i'433 

 volts being more nearly correct for the E.M.F. of a Clark 

 cell at 15° C. than the generally accepted (and legal) value 

 of 1-434 volts. The Helmholtz cell, recently modified by 

 Hibbert, is of interest on account of its having an 

 E.M.F. of I volt at 15° C. and also a very low temper- 

 ature coefficient, though in this latter respect it is inferioi 

 to the cadmium cell. The final chapter, on the carbon- 

 consuming cell, is, unfortunately, only a record of failures 

 It would seem as if commercial success, if ever to be 

 achieved, will have to be sought on entirely new lines 

 But the problem is not likely to lose its fascination 

 so long as the overall efficiency of steam generation 

 remains as low as 6 per cent, whilst the primary battery 

 holds out a prospect of the attainment of an efliciency oJ 



M.S. 



73 per cent, or more. 



A MEMOIR ON MORAINES. 

 Geschichtc der Mordncnkunde. \on Dr. August Bohn* 

 Edlen von Bomersheim {Abhandlungen der K. K. Geo- 

 graphischen Gesellschaft in ITien, iii. Band, No. 4). 

 Pp. viii -1-334 ; 4 plates, 2 figures in text. (Wien : R. 

 Lechner, igoi.) 



AS to the history of moraines, the author might fairly 

 say "What there is to know, I know it." By 

 patient research in libraries he has collected a great 

 mass of information, of which the present volume is a 

 summary. It also contains, besides the main subject, a 



