1869.] Mineralogy. 135 



ever become a popular study. Nevertheless, its value in the 

 diagnosis of mineral species — a value recognized even by those 

 who are least inclined to revert to the school of Mohs — should 

 be sufficient to call for its assiduous cultivation on the part 

 of all who are interested in mineralogical science. Crystallo- 

 graphy is indeed nothing but the morphology of the mineral 

 world ; and the one is every whit as needful to the mineralogist as 

 the other is to the biologist. To those, however, who take up the 

 study of mineralogy, not for its own sake, but merely as an aid to 

 the science of geology or to the art of mining, a very moderate 

 knowledge of rudimentary crystallography is all that can be ex- 

 pected, or is indeed necessary. Sach a knowledge may well be 

 gained from the little 'Guide to Descriptive Crystallograj^hy,' recently 

 written by Hochstetter and Bisching for special use in the study 

 of mineralogy.* Issued without a preface, the work speaks for 

 itself as an able and concise introduction to the science, which, 

 though hmited in its scope, is nevertheless sound and trustworthy. 

 After a discussion of the general ideas which lie at the root of the 

 science, the work deals in succession with each of the six "sys- 

 tems," or groups of related forms into which all crystals are 

 capable of division, and treats of both the holohedral and hemi- 

 hedral forms, together with the more important of their combina- 

 tions. The system of notation employed throughout the work is 

 that of Naumann, which still holds its ground as a favourite with 

 most beginners ; but as the book is pubhshed in Vienna, where 

 Grailich's translation of 'Miller' is extensively read, it is not 

 surprising that Miller's symbols are also given. The work is 

 illustrated by a profusion of woodcuts, and indeed without ample 

 illustration such a subject would be well nigh unintelligible. 



Perhaps no mineralogical treatise enjoys a more extensive 

 circulation as a text-book than Naumann's 'Elements.' The 

 seventh edition of this work, enlarged and improved, now lies 

 before us.f Of a book so well known little need be said. The 

 first section contains an outline of crystallography, which is cer- 

 tainly not the least valuable part of the work. This is followed 

 by a description of the physical properties of minerals, and an 

 introduction to their chemical characters. The second part — 

 which forms by far the larger portion of the book — is devoted to 

 systematic mineralogy, and after some preliminary ideas on the 

 principles of classification, proceeds with the physiography of 

 species. As descriptive mineralogy advances, this part of the work 



* ' Leitfaden der besclireibenden Kiystallographie. Zura Gebrauclie bei dem 

 Studium der Mineralogie.' Vou Dr. F. Hochstetter und A. Bisching. 8vo. 

 Vienna, 1868, pp. 85. 



f 'Eiemente der Mineralogie.' Von Dr. Carl Friedrich Nanmann. Siebeate, 

 verniehrte uud verbesserte Auflage. 8vo. Leipzig, 1868, pp. 566. 



