6i4 



NATURE 



[July 14, 192 1 



probability of the learned author being called upon 

 again to preside over such a gathering in Paris 

 as that which met there In 1907 to discuss the 

 universal language is, to say the least, very 

 remote. Nor have the prospects of German co- 

 operation in the International Association of 

 Chemical Societies, which Prof. Ostwald laboured 

 to found when in Paris, and the Belgian 

 manufacturer, Ernest Solvay, so generously en- 

 dowed, been rendered any brighter by Prof. Ost- 

 wald 's subsequent action in connection with the 

 notorious pronunciamiento of German " intel- 

 lectuals," directed against his quondam friends 

 in France and England. 



(2) Prof. Caven's book on "The Foundations of 

 Chemical Theory " is an attempt to explain the 

 fundamental conceptions which constitute the basis 

 of the modern theory of chemistry. It is avowedly 

 an introductory text-book, primarily intended for 

 the young student with an elementary knowledge 

 of the science ; but it is also hoped that it may be 

 within the compass of the general reader who, 

 in the words of the preface, "wishes to know 

 what modern chemistry really means." We fancy 

 that the general reader who peruses the book will 

 have a rude awakening in that respect. Recent 

 occurrences have led him to believe that modern 

 chemistry is mainly a matter of munitions — high 

 explosives and poison-gases. lie will find nothing 

 relating to these subjects in the book, but he will 

 be introduced to such eminently non-militant 

 matters as the atomic and molecular theory, the 

 periodic law, the doctrine of valency, reversible 

 reactions, complex ions, and catalysis. The scope 

 of the book is thus sufficiently indicated. In 

 fourteen chapters distributed over 262 pages the 

 author describes in simple and concise language 

 the main principles and facts upon which theo- 

 retical chemistry rests. 



The work is well written and forms interesting 

 reading. The judgment of the author is, however, 

 occasionally open to question. There are, for 

 example, two opinions as to the expediency of 

 the standard 0=i6 adopted, largely at the sug- 

 gestion of the Germans, by the International Com- 

 mittee on Atomic Weights. At the recent con- 

 ference in Rome it was proposed — and the pro- 

 position was favourably received — that the com- 

 mittee should revert to the old standard H = i . 

 Prof. Caven expresses the hope that no such modi- 

 fication of the standard will be made. There is 

 no question that any change will lead to confusion, 

 but it is open to doubt whether the consequences 

 will be so serious as Prof. Caven surmises. Even 

 under a constant standard there have been numer- 

 ous instances of changes in the value of an atomic 

 NO. 2698, VOL. 107] 



weight, due, not to the variable standard, but to 

 improvements in the methods of determining the 

 constant. The atomic weight of chlorine, which 

 the author adduces as an instance of confusion 

 due to a changing standard, has been referred to- 

 a constant standard for many years past; but the 

 value has suffered a progressive diminution owing 

 to more rigorous experimental inquiries. The 

 same is true of several of the fiduciary values- 

 employed in atomic-weight determinations. At 

 the same time, there is much to be said for the 

 retention of the present standard. It is remark- 

 able how many of the atomic-weight values ap- 

 proximate to whole numbers, and are thereby 

 more easily remembered and more convenient in 

 use. The contention of Stas has lost much of its 

 force, since the ratio of H : O is now known to- 

 a very high degree of accuracy. The question is 

 certain to be discussed by the reorganised com- 

 mittee in the near future, and it will largely turn 

 on the relative merits of rationalism and expedi- 

 ency, for which the recent re-issue of Lord 

 Morley's "Compromise" may well prepare the 

 members. 



For an elementary text-book the work may be 

 said to cover its subject-matter adequately, and it 

 is put together with a due sense of proportion. It 

 is reasonably up-to-date, and, so far as we have 

 been able to discover, it is free from errors. We 

 would, however, point out that Hofmann's name 

 in the .table of contents is wrongly spelled, and 

 the mistake is repeated on pp. 27 and 29. 



The student who works through this book care- 

 fully and intelligently will acquire a considerable 

 stock of chemical facts, and gain a sound know- 

 ledge of the generalisations to which they have led. 



(3) Mr. Lewis's book on inorganic chemistry, 

 originally published in 1907, is now in its third 

 edition. It is designed for school teaching, and 

 in the preface to the first edition, which is re- 

 printed, the author describes his methods and the 

 plan of his course of lessons. No attempt is 

 made to cover the whole ground of inorganic 

 chemistry; this is not called for where the main 

 object is to teach principles and illustrate them by 

 relevant facts. The plan of the work is original 

 and has evidently been well thought out; for 

 advice concerning it Mr. Lewis was indebted to 

 many Cambridge friends, among them the late 

 Mr. Humphry Jones and the late Mr. F. H. 

 Neville. Mr. Lewis is, indeed, very faithful to 

 h-s alma mater, and he loses no opportunity of 

 acknowledging his gratitude to her and her sons- 

 The lessons are accompanied by carefully chosen 

 experiments, the apparatus for which is illustrated 

 by figures in line drawing. 



