334 SCIENCE PROGRESS 



CRYSTALLOGRAPHY 



Crystallography and Practical Crystal Measurement. By A. E. H. Tutton, 

 D.Sc, M.A. (Oxon), F.R.C.S., A.R.C.Sc. Vol. I: Form and Structure. 

 Vol. II : Physical and Chemical. 2nd Edition. [Pp. xxxix + 1446, 

 with 8 plates, 931 text-figures.] (London : Macmillan & Co., 1922. 

 Price 50S. each volume.) 

 Crystallographers and chemists will note with satisfaction that attention 

 has been paid by the author to most of the criticisms and suggested improve- 

 ments to his well-known textbook on Crystallography and that, by an 

 extension into two volumes, the work has become almost completely com- 

 prehensive and brought well up to date. The whole study of Crystallography 

 has so increased its scope and utility by the far-reaching results of the applica- 

 tion of X-rays to the investigation of crystal structure, and the bonds of 

 alliance between Crystallography, Physics, and Chemistry so strengthened, 

 that these subjects form by far the greater part of the new material. 



A synopsis and critical survey of X-ray analysis by the methods of von 

 Laiie, the Professors Bragg and Debye and Scherrer, with special reference 

 to its interrelations with the 65 systems of Sohnckian points, themselves 

 illustrated, and the 230 space groups of Schonfiies, are treated excellently. 

 A small space is also devoted to the analysis of Crystals of the Carbon Com- 

 pounds, a field of research with infinite possibilities. 



The subject-matter of the author's works, " Crystalline Structure and 

 Chemical Composition " and " Crystals," is revised and incorporated into 

 these volumes, the very fine illustrations of the latter being reproduced, and 

 new chapters also on thermal, electrical, and magnetic properties are added. 

 The chapters on optical properties and determinations are considerably 

 amplified, but details are not always germane to the subject, such, for example, 

 as the colour of birds' wings, while an account of Konigsberger's determina- 

 tions of opaque minerals under the microscope might be added with impunity. 



Several of the weaker points of the first edition remain unchecked, and 

 some unencouraged tendencies pervade the new material. For whom is the 

 book written ? In an attempt to make the book both technical and popular, 

 the author has laid himself open to objections from both types of reader, 

 but especially from students. The latter will admit that the new edition is 

 a perfect mine of information, but how many would not have welcomed in 

 its place a single volume with many of the superfluities deleted ? We shall 

 see how this affects each part separately. 



The author admittedly avoids all " unnecessary " mathematical detaUs, 

 but he does not realise that a book should differ from a discourse or lecture 

 in that emphasis should be produced rather by explanation or proof than by 

 repetition. Simple analytical proofs, for example, of Weiss's Zone Law and 

 the Law of Anharmonic Ratios would serve a far better purpose than the 

 vast number of examples given of their application. The mathematical 

 relations between the elements of symmetry would also be welcome. 



In the second part of Volume I there is left little to be desired. Mallard's 

 views on pseudo-symmetry and its relation to twinning might have been 

 inserted, and the criticism of the Pope- Barlow theory might have been 

 dismissed in smaller space. 



Throughout the book, pre-eminence has been given to practical work, 

 but the description of some obscure types of apparatus is often disproportionate 

 to their importance in this connection ; we think that many details from the 

 realm of pure physics might have been replaced by reference to standard 

 works on this subject. Indeed, from the student's point of view, the style 

 adopted is too discursive, and more references, together with an improved 

 index, would be more satisfactory. The chapters on crystal chemistry, 

 however, are excellent and emphasise the true importance of this branch of 

 crystallography, while elaborate details of the author's own contributions 



