May 22, 1913] 



NATURE 



>9i 



the Mechanical Arts," published a little inure than a 

 century ago (1807), which, for its time, and as 

 the work of one man, was as wonderful as the 

 present index. The comparison affords a more 

 trustworthy indication of the advance of natural 

 knowledge during the nineteenth century than 

 could probablv be obtained in any other way. 



G. C. F. 



A NEW TEXT-BOOK OF MINERALOGY. 

 Mineralogy : an Introduction to the Theoretical 

 and Practical Study of Minerals. By Prof. 

 A. H. Phillips. Pp. viii + 699. (New York: 

 The Macmillan Co. ; London : Macmillan and 

 Co., Ltd., 1912.) Price 16s. net. 



PROF. PHILLIPS'S text-book on mineralogy 

 follows, on the whole, the usual lines of 

 such works, and in price and size comes inter- 

 mediately between Miers's well-known treatise, 

 which appeared eleven years ago, and Dana's 

 small book, a new edition of which, prepared by 

 Ford, was published recently. By his experience 

 in teaching the subject the author is well qualified 

 to write a book suitable for students who wish to 

 acquire a sound working knowledge of miner- 

 alogy. 



As will be evident from the titles of the three 

 parts into which it is divided, viz., crystallography, 

 descriptive mineralogy, and determinative miner- 

 alogy, the book is comprehensive in its scope. 

 Since each forms a subject wide enough to fill a 

 book in itself, the author of a work dealing with 

 all three is confronted with the difficulty of decid- 

 ing how to keep the size within reasonable dimen- 

 sions. On the whole, Prof. Phillips has succeeded 

 in well covering all the ground necessary for the 

 average student of mineralogy. We must acknow- 

 ledge a debt of gratitude to him for resisting the 

 temptation — irresistible to most writers on crystal- 

 lography — of devising a brand new set of names 

 for the thirty-two classes of crystal symmetry ; 

 he has wisely followed Miers, because the latter's 

 nomenclature embodies the type of symmetry, and 

 is therefore more easily remembered. Some sur- 

 prise may be felt that little trace of Penfield's 

 teaching should be evident in the discussion of the 

 method of drawing crystals ; the old one, in which 

 an axial-cross is used, alone is considered, and 

 no mention is made of the simple and convenient 

 methods based upon the stereographic or gno- 

 ^"nic projections. 



The whole subject of the goniometrical measure- 

 ment of crystals is treated in a very elementary 

 manner, and is confined to the instrument with a 

 single circle ; the theodolite goniometer, with two 

 circles, which is used by many crystallographers 

 NO. 2273, VOL. 91] 



in the United States, especially those who have 

 studied under Goldschmidt, is not referred to, and 

 it would seem that few students at Princeton 

 University prosecute their studies very deeply into 

 crystallography. The optical characters of 

 crystals, on the other hand, are more fully dealt 

 with, the reason no doubt being that an adequate 

 knowledge is essential to the practical petrologist 

 in the determination of the constituent minerals of 

 a rock from a microscopic study of a thin-section. 



The first part includes an interesting chapter on 

 the relations of individual crystals, in which atten- 

 tion is directed to the parallel growths of one 

 mineral on another, the full importance of which 

 subject has largely been brought out by Barker's 

 researches during recent years. 



The second part includes three chapters which 

 we should have imagined more in place in the first 

 part, viz., the relation of the minerals to the 

 elements, which covers such matters as topic para- 

 meters and the classification of minerals, the origin 

 of minerals, and, lastly, the physical properties — 

 for instance, cleavage and fracture, hardness, 

 specific gravity, structure, colour, phosphores- 

 cence, &c. The part proper is devoted to concise 

 descriptions of the characters and localities of the 

 principal mineral species. At the head we have 

 an abstract of their properties — chemical composi- 

 tion, crystalline system and type of symmetry, 

 common forms, hardness, specific gravity, streak, 

 colour, lustre, transparency, refractive indices — 

 and then follows a general description of the 

 crystals from the principal localities ; in certain 

 instances a few words are said about the use ot 

 the mineral or the metal derived from it. 



Part iii. is given up to the methods of blowpipe 

 analysis, the apparatus used, and the tables neces- 

 sary for the identification of the various minerals, 

 and is founded on Brush's well-known book. The 

 tables provided include also one for the determina- 

 tion of minerals from their physical characters, 

 dependence being placed mainly upon the hard- 

 ness, streak of the softer and colour of the harder 

 minerals, specific gravity, and cleavage, and 

 another for the determination of the principal rock- 

 forming minerals from their optical characters as 

 given in a thin-section. The book ends with a 

 full index, the use of which is facilitated by the 

 employment of a different type for the numbers of 

 the pages in each part of the book. 



So far as we have tested it, the book seems 

 satisfactorily accurate. Two curious mistake^ 

 have, however, crept into the description of the 

 Cullinan diamond, the date of the discovery being 

 wrongly stated to be June 6, instead of January 

 25, 1905, and the weight given being too high. 



