8o8 



NATURE 



[June 24, 1922 



for world markets, has more to fear from American 

 receptiveness to new ideas than from any other single 

 factor. 



In this country the support of the Department of 

 Scientific and Industrial Research in the foundation of 

 Research Associations is already more than justified 

 by its success in bringing together all types of employer, 

 engaged in particular industries. Contact with outside 

 scientific workers and their more enlightened com- 

 petitors will inevitably result in a greater appreciation 

 of the advantages of science by the majority of in- 

 dustrial leaders. 



Finally, the authors deserve credit for their just 

 appreciation of the special requirements of scientific 

 workers engaged in pioneer research, and particularly 

 of the ways in which such men may be encouraged to 

 prepare for research as a vocation and to follow it 

 without being repressed by works routine. The 

 necessity for supporting pure science work for its 

 paramount object of increasing the sum of human 

 knowledge is strongly emphasised. The book is 

 admirably produced and includes a 16-page biblio- 

 graphy, which should be of service to all interested in 

 the subject. 



R. S. H. 



Our Bookshelf. 



Physico-Chemical Problems relating to the Soil: a 

 General Discussion held by the Faraday Society. 

 (Reprinted from the Transactions of the Faraday 

 Society, Vol. 17, Part 2, February.) Pp. iii + 217- 

 368. (London : Faraday Society, 1922.) 105. 6d. 

 net. 



The Faraday Society is to be congratulated on the 

 issue of this volume, reprinted from its Transactions ; 

 soil investigators in this country now have, in accessible 

 form, a study of one important branch of work from 

 a number of aspects. The volume contains the subject- 

 matter of the general discussion held by the Faraday 

 Society in 1921 on " Physico-Chemical Problems 

 relating to the Soil." There are sixteen papers 

 grouped in the following five sections : (i) Intro- 

 duction and General Papers, (2) Soil Moisture, (3) 

 Organic Constituents of the Soil, (4) Adsorption 

 Phenomena, and (5) Colloidal Phenomena. The 

 student of soils will find much of interest, not only in 

 the papers themselves but also in the verbatim report 

 of the discussion which followed. 



Recent work on soils from the standpoint of physical- 

 chemistry has followed two or three main lines, which are 

 discussed in an introductory paper by Sir E. J. Russell. 

 The examination of the soil solution and its relation 

 to soils on one hand and plants on the other, has 

 been much stimulated by the method of the freezing- 

 point depression. American investigators have done 

 much in this direction, and the paper by Prof. Hoagland 

 (California) gives an interesting account of the work 

 to date. Certain assumptions are made in applying 



NO. 2747, VOL. 109] 



this method to the soil solution, and the deductions 

 which follow are discussed by B. A. Keen (Rothamsted) 

 in the course of a paper on soil moisture. Prof. 

 Shull (Kentucky) reviews various theories on the 

 intake of soil solution through the osmotically active 

 membranes of the root hairs. 



The part played by colloidal material in soil naturally 

 forms the subject of several papers. N. M. Comber 

 (Leeds) discusses the flocculation of silt and clay on 

 the assumption that the latter is protected by a 

 siliceous emulsoid, and C. G. T. Morison (Oxford) 

 reviews the theories of pan formation. Dr. Mellor 

 (Stoke-on-Trent) deals with the plasticity of clays 

 used in the ceramic industry. The organic matter in 

 soil is of obvious importance in any discussion of 

 colloidal properties. A general review is given by 

 H. J. Page (Rothamsted), and Prof. Oden (Upsala) 

 describes his own important investigations on humus, 

 which have proved the existence of humic acid and 

 shown that the hypothesis of selective adsorption is 

 not a complete explanation of soil acidity. With 

 regard to soil acidity itself there is one review paper 

 by E. M. Crowther (Rothamsted), while Dr. Salisbury 

 (London) discusses the ecological aspects. 



Besides acidity, many other phenomena shown by 

 soils have been interpreted on the basis of adsorption. 

 E. A. Fisher (Leeds) presents an able critical review 

 of work on absorptive processes in soils, with especial 

 reference to inorganic substances. 



Finally, there are some papers dealing with more 

 purely physical questions. Prof. Oden gives a detailed 

 account of his elegant method of mechanical analysis 

 and a note on the hygroscopicity of clay. Dr. Hackett 

 (Dublin) discusses the rate of ascent of liquids in 

 granular media, while G. W. Robinson (Bangor) specifies 

 certain phvsical properties of soil in relation to survey 

 work. ' B. A. K. 



A Text-Book of Aeronautical Engineering : The Problem 

 of Flight. By Prof. LI. Chatley. Third edition, 

 revised. Pp. xii + 150. (London: C. Griffin and 

 Co., Ltd., 1921.) 15^. net. 

 A SECOND edition of Prof. Chatley's book appeared in 

 1910, and during the war, when interest in aeronautics 

 attained great heights, this book, like many others on 

 the subject, was bought in large numbers, thus neces- 

 sitating a third edition. Not very much was known 

 about the subject of aeronautics before the war ; 

 systematic treatises had not yet appeared, and Prof. 

 Chatley's book achieved a deserved popularity. 



Now that a third edition has been issued, claiming 

 to be " revised," the opportunity should have been 

 taken to make the book a more proportioned, authori- 

 tative, and modern exposition. There is scarcely room 

 in a text-book for a detailed account of the ornithopter 

 — not because it is a priori clear that one should not 

 continue to make attempts at producing machines 

 based on the flapping-wings principle, but because a 

 text-book should contain what is more or less accepted : 

 it should give a safe (not necessarily orthodox) account 

 of the principles used in practice, with some attempt 

 at justification. 



A brief introduction on the problem of flight is 

 followed by a useful statement of essential principles. 

 Then comes a chapter on the propeller, treated by 



