NATURE 



217 



THURSDAY, JULY 7, 1892. 



A SYSTEM OF MINERALOGY. 

 The System 0/ Mineralogy 0/ James Divight Dana, 1837- 

 dZ: Descriptive Mineralogy. Sixth Edition. By Edward 

 Salisbury Dana, Professor of Physics, and Curator of 

 the Mineral Collection, Yale University. Entirely re- 

 written and much enlarged. Pp. Ixiii. and 11 34. Illus- 

 trated with over 1400 Figures. (New York and London : 

 Kegan Paul, Trench, Trubner, and Co., 1892.) 

 T N the whole history of scientific literature it would be 

 -*- difficult to find a parallel to Dana's "System of 

 Mineralogy," for there is probably no work which, like 

 it, has maintained for more than half a century its 

 position as the best and most complete work of reference 

 on a branch of natural history. In spite of the enormous 

 additions to our knowledge of the chemical and physical 

 properties of well-known minerals, and of the discovery 

 of innumerable new species and varieties, during that 

 long period, the work has been carefully kept up to 

 date ; and so thorough and judicious have been the re- 

 visions to which successive editions have been subjected, 

 that the book may at the present time fearlessly challenge 

 comparison with the latest and most successful attempts 

 to supply a comprehensive survey of mineralogical 

 science. 



When the work first appeared, in 1837, its author made 

 a determined attempt to grapple with the difficult prob- 

 lem of mineralogical nomenclature and classification ; 

 like many of his contemporaries, he was sanguine of 

 being able to make the taxonomy of mineralogy corre- 

 spond with that of the other natural-history sciences, 

 and a so-called natural system of classification, based on 

 that of Mohs, was adopted by him. But on the appear- 

 ance of the third edition in 1850 the futility of all such 

 attempts was admitted, and a scheme of classification 

 founded upon chemical composition was substituted ; it 

 is this system of classification which, with some modifica- 

 tions rendered necessary by the progress of discovery, is 

 employed in the present edition. 



On reaching its fourth edition in 1854, the work had 

 grown to such an extent that it became necessary to 

 divide it into two volumes : the first devoted to a general 

 introduction to crystallography, with mineral physics and 

 chemistry, and the second to descriptive mineralogy. 

 The necessity for the re-issue of the first of these volumes 

 has been obviated, however, by the publication in 1875 of 

 the " Determinative Mineralogy " by the author's friend 

 and fellow-worker, Prof. Brush, and by the appearance, 

 two years later, of the *' Text-book of Mineralogy," in 

 the preparation of which the author had the able co- 

 operation of his son, Prof. Edward Salisbury Dana. In this 

 way the " System of Mineralogy " has now been limited 

 to the descriptive portion of the original work, and only a 

 few pages of introductory matter are given to explain the 

 terminology, symbols, and abbreviations which it has 

 been found necessary to employ. A noteworthy change 

 in the fifth edition, and one which has tended to greatly 

 increase the value of the work for reference purposes, 

 was the fuller recognition and description of varieties^ 

 NO. 1 1 84, VOL. 46] 



and of the localities from which they have been ob- 

 tained ; the very thorough revision of the historical 

 synonymy, which was undertaken for this fifth edition, 

 also greatly enhanced the usefulness of the book. These 

 historical details and references, which have entailed a 

 vast amount of bibliographical research, have been re- 

 tained with but few modifications in the present edition. 



In the preface to) this fifth edition. Prof. Dana wrote 

 in 1868 as follows: — 



" In these and other ways the volume has unavoidably 

 become enlarged. Not a page, and scarcely a paragraph, 

 of the preceding edition remains unaltered, and fully five- 

 sixths of the volume have been printed from manuscript 

 copy. I may here add that, notwithstanding the im- 

 paired state of my health, this manuscript— the paragraphs 

 on the pyrognostic characters excepted — was almost 

 solely in the handwriting of the author, or in that of a 

 copyist from it. Neither the consultation of authorities, 

 the drawing of conclusions, nor the putting of the results 

 on paper, has been delegated to another. And being now 

 but half-way between the fifties and sixties, it is my hope 

 that the future will afford another opportunity for similar 

 work." 



In writing these lines. Prof. Dana could scarcely have 

 foreseen that the issue of the sixth edition of the work 

 would be delayed for 24 years. During that period three 

 appendices have been prepared by the author, and he 

 has shown, in numerous books and original memoirs on 

 various branches of geology and natural history, an un- 

 abated interest and zeal in scientific work. But the very 

 heavy task of incorporating the matter of the appendices 

 into a new edition, and of revising and re-arranging 

 the whole work, has had to be delegated by the author 

 to his son, and certainly it could not have been placed in 

 more competent hands. Every mineralogist will rejoice 

 that the familiar and excellent features of the original work 

 have been carefully preserved. The book, indeed, is so well 

 known to all working geologists and mineralogists, that 

 we cannot do better than to indicate the chief changes 

 which have been found necessary in the present edition, 

 in order to bring it up to date and maintain its high 

 character. 



The work now contains more than one-half more matter 

 than the fifth edition, and, to keep it down even to this limit, 

 a very rigid system of abbreviation and condensation has 

 had to be adopted, while the size of the page has been 

 increased by one-fifth. The historical account of the 

 species remains substantially the same as in the last 

 edition, but names commonly employed in important lan- 

 guages, in addition to English, French, and German, have 

 been given. 



In the chemical portion of the work very considerable 

 changes have been introduced. The difficult question of 

 the classification of the silicates has received the fullest 

 consideration, and the views of Rammelsberg,Tschermak, 

 and other chemists on each species are clearly indicated. 

 It has no longer been found possible, however, to give a 

 statement of all the analyses that have been made of a 

 species. The microscopic work of Lacroix and others 

 has shown that many of these analyses are worthless, as 

 the material operated upon has been a mixture and not 

 a homogeneous substance. In the present edition all 

 trustworthy analyses of rare minerals have been given, and 



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