April i, 1920" 



NATURE 



129 



I 



on p. 76 are very good, but the statement on p. Si 

 that from four to eight fiUings are commonly 

 given to pots is not a fact in practice. The prin- 

 ciples of annealing discussed in the latter half of 

 chap. vii. are most useful, and confirm the 

 conclusions arrived at by Mr. F. W. Twyman in 

 his paper read before the Society of Glass Tech- 

 nology at Sheffield in February, 1917. 



Bottle glass, rolled or plate glass, sheet glass, 

 and crown glass are well explained in general 

 principles in chaps, ix., x., and xi. Chap, xii., on 

 "Coloured Glasses," is good on the whole, but 

 the author has entirely missed the real function 

 of arsenic and antimony in glass-making. The 

 important question of optical glass is treated in 

 chaps, xiii. and xiv., and the requirements are 

 \ery lucidly explained, but only old methods are 

 detailed ; modern developments in manufacture in 

 this branch of the industry are not even mentioned. 



The book is well indexed, and will be read with 

 much interest by both users and makers of glass. 



Physical Chemistry. 



(i) Introduction to Physical Chemistry. By Prof. 

 James Walker. Eighth edition. Pp. xiii + 433. 

 (London: Macmillan and Co., Ltd., 1919.) 

 Price 165. net. 



(2) Stereochemistry . By Prof. Alfred W. Stewart. 

 Second edition. (Text-books of Physical 

 Chemistry.) Pp. xvi + 277. (London: Long- 

 mans, Green, and Co., 1919.) Price 12s. 6d. 

 net. 



(3) La Tension de Vapeur des Melanges de 

 Liqiiides : L'Azeotropisme. By Dr. Maurice 

 Lecat. Premiere partie : Donnees expdri- 

 mentales ; Bibliographie. Pp. xii + 319. 

 (Gand : Anct. Ad. Hoste, S.A. ; Bruxelles : 

 Henri Lamertin, 1918.) Price 45 francs. 



(i)pROF. WALKER'S "Introduction to 

 1 Physical Chemistry " has, since its first 



appearance in 1899, been recognised in this 

 country as the standard work for beginners in this 

 branch of science. No great changes from 

 previous editions appear in the present one ; the 

 "selected chapter" method of treatment is em- 

 ployed, each branch of the subject being treated 

 from the point of view of showing how physico- 

 chemical principles are applicable to the student's 

 own practical work in inorganic and organic 

 chemistry. Its past success is no doubt due to 

 this and also to the sound and thorough manner 

 in which the explanatory portions are dealt with. 



The arrangement of the subject-matter is much 

 the same as in previous editions ; two new- 

 chapters have, however, been added, one dealing 

 NO. 2631, VOL. 105] 



with "Atomic Number," and the other with 

 "Atoms and Electrons." Several of the chapters 

 have been revised, and a number of additions 

 made with the object of bringing the work up to 

 date. Such additions include brief accounts of 

 Ghosh's equation (1918) to account for the abnor- 

 mality of strong electrolytes and of Dieterici's 

 equation of state, while mention is made of 

 recent work on specific heat at low temperatures 

 and also of the isotopic elements. A useful 

 feature of the book is a list of important refer- 

 ences to the appropriate literature at the end of 

 each chapter. This is a book which can be warmly 

 recommended to students of chemistry. 



(2) The author states in the preface to the new 

 edition : 



"In general I have tried to condense 

 and re-write the material in such a way as to 

 convert what was, perhaps, too much of a refer- 

 ence book into a more readable text-book. At 

 the same time, by the retention of the references 

 given in the previous edition, the volume still 

 maintains its value as a guide to the literature." 



"Certain reviewers of the first edition criticised 

 adversely the amount of space devoted to steric 

 hindrance, and in preparing the new edition I 

 have come to the conclusion that they were right, 

 the more so since this subject now attracts less 

 attention than other branches of stereochemistry 

 do. The portion of the volume devoted to steric 

 hindrance has therefore been markedly 

 diminished." 



The plan of the first edition has been followed 

 throughout ; two new chapters have been added, 

 one being allotted to the Walden inversion, and the 

 other to "The Arrangement of Atoms in Space," 

 a short account of the X-ray work of Profs. W. H. 

 and W. L. Bragg. The book contains three 

 appendices, the first being an interesting account 

 of the relation between physiology and stereo- 

 chemistry, the second giving directions for making 

 solid models, the employment of which is a great 

 aid to following the subject, and the third contain- 

 ing references to literature on the subject of steric 

 hindrance. The author has succeeded in giving 

 a critical survey of his subject, including recent 

 important work. The book is well got up and 

 illustrated, but contains a few misprints, which, 

 however, are of a minor character. 



(3) This book, which was published in Belgium 

 during the German occupation, deals with a very 

 specialised branch of physical chemistry. Azeo- 

 tropic mixtures are defined as liquid mixtures 

 which, under constant pressure, distil at a con- 

 stant temperature, their composition correspond- 

 ing to a maximum or a minimum in the vapour 

 pressure-composition diagram. The work is a 



