Notices respecting New Books. 279 



elegant theory of electrolytic solution pressure and applied it to 

 explain the action of a primary cell, it was thought that at last a 

 satisfactory solution of the problem had been arrived at. Unfor- 

 tunately, some recent work has placed serious obstacles in the way 

 of JNernst's theory, and the theory of ionization has by no means 

 received unqualified support from physicists. 



It is probably owing to the somewhat chaotic state of the theory 

 that no writer was found bold enough to write a comprehensive 

 treatise on the primary cell, dealing with it in all its aspects. This 

 task has now been accomplished — and accomplished most success- 

 fully — by Mr. W. R. Cooper in the book before us. 



In the first few chapters we have a brief historical introduction 

 and an account of the actions going on in a simple voltaic cell, 

 including local action and polarization. Exception might be taken 

 to the manner in which some of the terms are defined in these 

 early chapters. Thus, electromotive force is explained to mean 

 " that force which causes the current to flow in any circuit." This 

 semi-popular method of definition seems somew T hat out of place in 

 a book which is not intended for beginners. In chapters IV. and 

 V. we have a very clear and interesting account of the theory of 

 the voltaic ceil ; a careful perusal of these chapters will probably 

 convince the reader that the theory of the voltaic cell has by no 

 means reached finality. Chapter VI. deals with non-chemical cells 

 and thermopiles. Some useful hints are contained in the next 

 chapter, on the testing of cells. Then follows a detailed account 

 of various forms of cells, the subdivision into one-fluid, two-fluid, 

 and dry cells being adopted. Standard cells receive special 

 consideration in Chapter XI. 



Since the introduction of the dynamo as a generator of electrical 

 energy, the field of usefulness of the primary cell has been consi- 

 derably restricted. In all cases, however, in which comparatively 

 small currents are required at intervals, the primary cell has been 

 able to hold its own. As standards of E.M.F., certain forms of 

 cells will always be used. Within recent years, however, numerous 

 attempts have been made by various inventors to produce a pri- 

 mary cell which should rival the steam-engine and dynamo as a 

 current-generator. For this purpose the cell must be arranged to 

 consume a cheap fuel — carbon. To all those who hope for great 

 things from a carbon-consuming cell we earnestly commend the 

 closing chapter of Mr. Cooper's book, in which the subject of 

 carbon-consuming cells is dealt with in a masterly fashion. The 

 enthusiasts who look for a complete revolution in the cost of pro- 

 ducing electrical energy when the long-wished-for carbon-consuming 

 cell makes its appearance, will be somewhat sobered by the clear 

 and critical account of the subject which is to be found in 

 Mr. Cooper's book. Such enthusiasts entirely overlook the fact 

 that the cost of the fuel forms only one item in the total cost 

 of production. Even a carbon-consuming cell would not enable 

 us to obtain electrical energy at an entirely trifling cost. But 



