3o6 



NA TURE 



[September 2, 1922 



from the non-magnetic into the magnetic condition 

 are represented by lines, which show the formation of 

 a definite series of solid solutions, instead of by blurred 

 areas. The appendix, in which the various binary, 

 ternary, and quaternary systems which have been 

 studied are classified and summarised, has been revised 

 to include publications received down to the time of 

 going to press. The new edition incorporates the 

 results of nine years of work in metallography, and it 

 can be heartily commended for its up-to-date presenta- 

 tion of this important subject. 



(3) The first edition of Dr. Hilditch's " Concise 

 History of Chemistry " was reviewed in Nature of 

 October 19, 191 1, p. 510. The new edition has been 

 expanded from 263 to 276 pages, and, in view of the 

 number of additional topics that have come into 

 prominence during the past ten years, it is clear that 

 the conciseness of the old edition has been at least 

 fully maintained in the new. It will thus be found that 

 the nucleus atom, X-ray analysis of crystals, Moseley's 

 atomic numbers, the octet theory of Langmuir and the 

 discovery of isotopes, are all described in the course of 

 three pages in the chapter on the " Ultimate Constitu- 

 tion of Matter," although another page is given later 

 on to some of these subjects. Gas warfare is described 

 in a paragraph of eleven lines, and " anti-gas " is 

 summed up in a paragraph of four lines. In a few 

 details only the revision is perhaps incomplete, e.g. 

 the list of the metals of the rare earths is still that of 

 1909, with holmium omitted, and the atomic weights 

 (which are of the same date) might well have been 

 supplemen'.ed by giving also the atomic numbers ; 

 moreover, the new matter is by no means fully repre- 

 sented in the subject index, although the author-index 

 appears to have been revised. The value of the book 

 as an index of chemical discoveries is preserved in the 

 new edition, although it would obviously be useless to 

 look for detailed descriptions in so compact a volume. 



(4) Prof. Washburn's " Principles of Physical 

 Chemistry " was reviewed in these columns on June 

 1, 1916, p. 277, and has established a wide reputation 

 in this country as well as in the country of its origin. 

 As the first edition appeared but seven years ago, only 

 those subjects which have developed since the war 

 have called for further elaboration. These include, 

 however, the work of Aston on isotopes and all the 

 recent work on atomic and molecular structure. It is, 

 indeed, remarkable evidence of the rapid progress 

 which has been made in this field that, while the first 

 edition stops with an account of the qualitative aspects 

 of the periodic classification, and of the models which 

 Soddy and Harkins put forward in order to explain the 

 sequence of properties, these two figures have dis- 

 appeared in the second edition in favour of a large chart 



NO. 2757, VOL. I 10] 



illustrating the Lewis-Langmuir theory ; and this 

 chart in turn is probably already obsolete in view of the 

 suggestions put forward by Bohr for making use of 

 the quantum-orbits of the electrons as a basis for the 

 periodic classification of the elements. The work on 

 the X-ray analysis of crystal-structure, which was 

 briefly mentioned in the first edition, claims eight pages 

 in the second edition. Anisotropic liquids are, how- 

 ever, inadequately (and perhaps incorrectly) dealt 

 with, especially in view of recent French work on this 

 subject. 



(5) Dr. Michaelis's book on " Hydrogen Ion Con- 

 centration " was first issued in 1914. The present 

 volume is a new edition of the first and theoretical part 

 of the book, and covers two main topics, namely, the 

 chemical equilibrium of ions and ions as sources of 

 differences of electrical potential. The subject has 

 attracted even more attention from physiologists than 

 from chemists, and Dr. Michaelis's book is actually 

 issued as the first volume of the series of monographs 

 on physiology ; but this does not detract from its value 

 to physical chemists, and especially to those who are 

 liable to be called upon to answer the conundrums of 

 their biochemical colleagues. 



Phosphatic Fertilisers. 



Basic Slags and Rock Phosphates. By Dr. G. Scott 

 Robertson. (Cambridge Agricultural Monographs.) 

 Pp. xvi + 120. (Cambridge: At the University- 

 Press, 1922.) 14s. net. 



DURING and since the war the position in this 

 country with regard to the supply of basic 

 phosphatic fertilisers has undergone a radical change. 

 On one hand, the ousting of the older Bessemer process 

 by the modern open hearth process of steel-making 

 has led to the virtual disappearance from the market 

 of the high grade basic slag to which the agriculturist 

 was accustomed, and its replacement by a totally 

 different material of much lower phosphorus content 

 and frequently of low " citric-solubility." On the 

 other hand, the development of the extensive deposits 

 of rock phosphate in the Pacific Islands has rendered 

 available greatly increased amounts of this material. 

 The field experiments at Cockle Park, from which most 

 of our knowledge of the value of basic slag in agricul- 

 ture was derived, were carried out with the now obsolete 

 high grade Bessemer material, and prior to Dr. Robert- 

 son's experiments practically nothing was known as to 

 the fertilising value of the new open hearth slags ; 

 the experiments in this country on raw rock phosphate 

 were also few in number and not very conclusive in 

 result. 



