ioS 



NATURE 



[July 27, 191 1 



worked out. Where required, the exercise is ex- 

 plained by means of a diagram. It is recognised that 

 certain preliminaries are required to enable the student 

 in understand electrical problems, and, to this end, 

 the earlier questions relate purely to mechanics, hydro- 

 . and heat. The examples are very varied in 

 type, and include cases of interest, both theoretically 

 and practically. There follows a short section in 

 which the various mechanical, thermal, and electrical 

 units arc defined, and the book concludes with 

 numerous tables, in which these units are collected, 

 together with others giving the values of the various 

 physical constants required in the working of the 

 exercises. 



It is somewhat doubtful whether the procedure of 

 asking a question and at once giving the answer can 

 be of much benefit to a student. It surely tends to 

 discourage the use of the student's own initiative. A 

 few illustrative worked examples should suffice, the 

 rest being left for the learner to undertake. 



The book is well printed, but it may be mentioned 

 that some six of the introductory pages are missing 

 from the copy submitted to the reviewer; it is to be 

 hoped that this mistake does not extend to the whole 

 edition. 



(2) The second edition of this excellent treatise on 

 electricity and magnetism, by Prof. Starke, has been 

 brought thoroughly up to date by the addition of 

 numerous paragraphs and chapters. Besides all the 

 experimental and theoretical considerations usually 

 found in text-books on this subject, many special 

 electrical applications are deal with at length. Par- 

 ticular attention is given to the production and pro- 

 perties of electro-magnetic waves and to the practical 

 uses of the latter in wireless telegraphy and telephonv. 

 As indicated in the title, the electro-magnetic theory 

 lit is also deall with, especially the explanations 

 of the vario phenomena upon tin- electron 



theory. In the thirteenth chapter this theorv is ex- 

 tended to thermal and electrical conduction, and to 

 the different thermo-electric effects. The section 

 devoted to the conduction of electricity in gases has 

 been largely added to, so that most of the latest work 

 in this department of physics is considered. The new 

 chapter on radio-activity gives a brief general outline 

 of the rapidly progressing work which has been done 

 in this direction, and includes a table giving the 

 various radio-active substances at present known, their 

 life-periods, types of ray-., and physical properties. 

 Finally, the authi an appendix of consider- 



able I' ngth to the theorj of moving electrons and the 

 principle of relativity. 



[never} n ;pecl this book has claims to be regarded 



as a standard work on electro-magnetism. The 



iiions and additions in this edition have brought 



it, as far as possible in a general text-book, to the 



level of modern scientific research. To all those 



desirous of becoming acquainted with tin- pi 



state ot knowledge' in this subject it can there- 



hlv recommended. It may also be 



tioned that the type, diagrams, and papei ari 



excellent. 



NO. 2178, VOL. 87] 



LLU1 OSE EPHEMERIDES. 

 Literatur der Zellstoff- und Papier-Chcmie und 



Papier-Technik im Jahre 1909. In Ausziigen 



dargestellt. By Prof. C. G. Schwalbe and \. Lutz. 



Pp. 158 + xix -H14. (Berlin: Gebriider Borntraeger, 



nil i.) Price 5 marks. 

 Zur Kenntnis der Cellulosearten. By Dr. W. Schulz. 



Nebst einem Vorwort, by Prof. C. G. Schwalbe. 



Pp. vi+100. (Berlin : Gebriider Borntraeger, 1911.) 

 . Price 3.20 marks. 



THESE publications are indicative of the extra- 

 ordinary specialisation of cellulose chemistry, 

 and at the same time of a tendency to intensive 

 elaboration of detail in investigation, and more par- 

 ticularly of records, which, however interesting to the 

 specialist, are drawn in too narrow a perspective to 

 rank in the general literature of the science. 



The former is a bibliographical record, sufficiently 

 defined bv its title. It is produced under the auspices 

 of a youthful technical society, the " Verein der Zell- 

 stoff- und Papier-Chemiker," which is doing much use- 

 ful work, and very fully justifying its foundation and 

 existence. The matter of the volume is exhaustive, 

 the records take the form of abstracts, which are 

 duly concentrated and presented under a well-con- 

 sidered scheme of classification, with full indexes. 



The second volume is a record of research towards 

 establishing a method of diagnosing the more im- 

 portant industrial celluloses in terms of differentiating 

 factors. This work is evidently inspired by Prof. 

 C. G. Schw-albe, and in a short preface he claims for 

 the author's results at least a definite promise of 

 achievement, a claim which is somewhat at variance 

 with the conclusions recorded en risumi on pp. S5-S6, 

 99-100; these are rather of negative import. 



The main scheme of investigation is a study of 

 acid hydrolysis, taking as a measure of the degree of 

 hydrolysis the reactions of the products with alkaline 

 cupric oxide (Fehling's solution), and as a first stage 

 (a) combination in the cold with cupric oxide (hydrate), 

 ami secondly (b) reduction to cupric oxide, on boiling. 



The quantitative determinations are recorded under 

 a special nomenclature, thus: — " Cellulosezahlen " (a) 

 "Korrigierte Kupferzahlen " (b-a); end after the par- 

 ticular hydrolytic treatment " Hydrolysierzahl " (b') 

 and ''Korrigierte Hydrolysierzahl" (6 a'). 



The numbers recorded for a selection of ten typical 

 marks of sulphite celluloses are, as the author admits 

 (loc. cit.), unconvincing. An a priori consideration of 

 the method would, we think, have enabled the author 

 to predict the generally inconclusive result. It has 

 been long established that the hydrolytic resolutions 

 of cellulose can proceed very far under the action 

 both of acids and alkalis without liberating CO 

 groups. It i-i dear therefore that cupric reduction is 

 nih :i partial measure of cellulose hydrolysis. And 

 ri i i.dly oxidations by alkaline cupric oxide are 

 highly complex reactions, even tin classical reactions 

 with the sugars are by no means well defined, and 

 remain therefore of essentially empirical order. With- 

 out detracting in .m\ wa\ from the author's results 

 as quantitative observations, we suggest that they 



