374 



NA TURE 



[September 16, 1922 



the reader is gratified by a brief description of the theory 

 on which the device is founded, but in many cases no 

 hint is given. 



In our opinion the value of the book would be very 

 greatly increased by additional brief descriptions of 

 the physical laws which govern the action of many of 

 the devices used by engineers. For example, a table of 

 the rating factors by which the voltage of a given circuit 

 breaker must be multiplied so as to get its rating at 

 various heights above the sea level is given. It would 

 be useful to give the theory used by the General Electric 

 Company of America in getting these numbers. 



Many types of the spark gaps used in practice are 

 given, and it is pointed out that the sphere gap has a 

 greater speed of discharge than the horn gap. The 

 " impulse gap," tvhich we believe was perfected during 

 the war in connexion with the spark gap used in the 

 magneto circuit of an aeroplane, is now adopted for 

 lightning arresters. The Westinghouse Company state 

 that it is more efficient than any other spark gap. An 

 investigation of the action of the lightning arresters 

 described would be a very promising field of research 

 for the pure physicist. 



In reading this book one gets accustomed to the 

 American words " resistor " and " reactor " which 

 are used for " resistance " and " reactance coil " 

 respectively, and these words might well be adopted 

 -in this country. Electrical engineers talked about 

 " omnibus bars " thirty years ago, it then became 

 " bus bars," and now apparently it has become 

 " busses." This book will be useful to the switchgear 

 expert. A. R. 



A Modern Text-book of Chemistry. 

 Inorganic Chemistry. By Prof. T. M. Lowry. Pp. 

 xi + 943. (London : Macmillan and Co., Ltd., 1922.) 

 285. net. 



FIFTY years ago there were no books on physical 

 chemistry. The work which had been done on 

 the borderline of physics and chemistry was scattered 

 in different journals and was not readily accessible to 

 the student. The first volume of Miller's " Chemistry," 

 Tilden's " Chemical Philosophy," and certain articles 

 of the old Watts's " Dictionary " were the first available 

 summaries of what is now one of the most important 

 branches of the subject. The works of Lothar Meyer 

 and Ostwald, published in the late 'seventies of the last 

 century, did much to direct attention to the importance 

 of physical chemistry. The first professor of physical 

 chemistry was appointed only twenty-five years ago, 

 and even now this branch of the subject is still allotted 

 to a lecturer at some of the universities in this country. 

 NO. 2759, VOL. I IO] 



It is now recognised that inorganic and organic 

 chemistry will become a mere record of facts, the inter- 

 pretation of which, without the aid of physical chemistry, 

 will remain undisclosed. It is therefore a matter of 

 congratulation to the publishers that they should have 

 been able to arrange for the publication of a book on 

 inorganic chemistry by a physical chemist. The 

 author is also to be congratulated on the way in which 

 he has fulfilled his task. Perhaps the severest test of 

 such a book is to refer to all the parts of the work 

 which one knows are stumbling-blocks to the ordinary 

 intelligent student. Prof. Lowry 's book stands this 

 test remarkably well ; in one case alone, the liquefac- 

 tion of gases, will the information need to be supple- 

 mented by the teacher. If it had been possible to give 

 the references to original papers the book would have 

 sufficed for any chemist who was not intending to 

 devote himself to inorganic chemistry as his main 

 subject, although the author in his preface seems to 

 disclaim the use of his book as a book of reference. 



The book is admirably produced, and the illustra- 

 tions are remarkable, no less for their number than 

 for their clearness. The book may be heartily recom- 

 mended. II. B. Baker. 



Our Bookshelf. 



Drahtloser Ubersee-Vcrkehr. Von Dr. Gustav Eichhorn. 

 Pp. 69 + xx. (Zurich: Beer et Cie, 192 1.) 7 francs. 



In the first two chapters of the publication under 

 notice, an excellent description is given of the great 

 German radio-station at Nauen and of the receiving 

 station at Geltow, twenty miles south of it. The 

 third chapter discusses the theory of thermionic 

 tubes, and the method of indicating the paths of 

 tin- various currents by marking them in different 

 colours is to be commended. The last chapter 

 on radio-telephony is concerned mainly with modern 

 German practice. In the Appendix a few well-known 

 papers by Howe, Vallauri, etc., are published. The 

 book is clearly printed, and the photographs of the 

 Nauen station and the great lattice towers with their net- 

 works of wires show on what a huge scale it is designed. 

 During the last few years the station has been 

 practically redesigned. The standard system of trans- 

 mission does not yet seem to have developed. For 

 example, they are at present constructing seven new 

 towers, each 210 metres high, to enable them to com- 

 municate with Argentina. Under favourable atmo- 

 spheric conditions the Telefunken Co., who own the 

 station, have maintained communication with Japan 

 for several years, although the messages have to go 

 1 Airland across Europe and Asia. The antennas can 

 be separated into four separate sections, each of which 

 can be attached to a separate transmitter. When 

 weather conditions are adverse all the antennas can be 

 connected in parallel. They then have a joint capacity 

 of o-oi microfarad. The two largest sections are each 



