PETROLOGICAL ABSTRACTS AND REVIEWS 483 



Holmes, Arthur. The Nomenclature of Petrology. London, 1920. 

 Pp. 284. 



This little book is intended as an English substitute for Loewinson-Lessing 's 

 Lexique Petrographique, which is now about twenty years old. It is a very 

 convenient and useful volume, giving in brief form, definitions of most of the 

 common terms used in petrology. The only fault that might be found with 

 it is that it is too brief, and that the references are, in many cases, not to the 

 work in which the term was originally given, but usually to later British authors. 

 In other cases references are hard to find; for example, the reference for the 

 source of umptekite is under "chibinite," and maenaite imder "grorudite," but 

 this can hardly be called satisfactory, especially since no hint is given as to the 

 terms under which they may be found. Other references, such as " Syenodio- 

 rite, Evans, 1916," etc., are too incomplete to be traced. On the whole, how- 

 ever, the book is very good, and it is likely to prove useful to students by giving 

 them the means for quickly finding unfamiliar terms. 



Holmes, Arthur. Petrographic Methods and Calculations. Lon- 

 don, 192 1. Pp. 515, figs. 83, pis. 4. 



Quite different from previously published books on petrographic methods 

 is this one by Holmes, in that very little space is devoted to optical methods. 

 The author says in his preface, "I have tried to produce a more evenly balanced 

 treatise which should penetrate the petrological domain, and not merely skirt 

 its border land." Chapter i deals with Petrology, its scope, aims, and applica- 

 tion, chapter ii with specific gravity, chapter iii (40 pp.), separation of minerals 

 by heavy liquids, magnet, etc., chapter iv (52 pp.), optical examination of min- 

 erals, including not only optical properties but tables for the determination of 

 minerals, chapter v (71 pp.), the examination of detrital sediments, chapter vi 

 (19 pp.), the preparation of thin sections, chapter vii (45 pp.), microchemical 

 and staining methods, chapter viii (38 pp.), the examination of thin sections, 

 including a discussion of the Rosiwal and similar methods, genesis of minerals, 

 saturated and unsaturated minerals, etc. Incidentally it is stated that " Jo- 

 hannsen has suggested the use of a planimeter for measuring areas of particular 

 minerals on a drawing of a thin section made with the aid of a camera lucida. 

 The procedure is more complicated and tedious than the ordinary linear method 

 now in general use." But in the method mentioned no camera lucida drawing 

 is made and the time requireid is less than a fourth of that of the Rosiwal. 

 Chapter ix deals with rock textures, chapter x with chemical analyses and 

 their interpretation and includes a discussion of the C.I.P.W. system, and 

 chapter xi with graphical representation of chemical analyses. The book 

 thus brings together much of the miscellaneous data so often needed by the 

 petrographer. It wiU therefore be examined with interest and profit by all 

 advanced workers in the science. 



