Reviews — Dana's Mineralogy. 461 



whose skill in analytical chemistry and thorough knowledge of mine- 

 rals have enabled him to afford aid and advice, as well as furnish new 

 facts on various points during the progress of the work. The pyrog- 

 nostic characters have been entirely rewritten by him, — personal 

 trials of the blowpipe and other reactions having been made for the 

 larger part of the species before writing them out. 



Mineralogy is a science which, unfortunately for the student, varies 

 considerably in the classification of its objects, according to the views 

 of each writer or curator, whether it be in a descriptive treatise or 

 the arrangement of a museum. Various, indeed, have been the 

 classificatory systems for minerals, from that of Werner, who simply 

 divided them into earths and stones, salts, metals, and combustibles, 

 to those used at present. Nor is the same author always consistent, 

 for during the thirty-one years that have elapsed since the first 

 appearance of his ''Mineralogy" (1837), Professor Dana has 

 considerably modified his views of the classification of mineral 

 species, in each successive edition, — from that of a strictly natural 

 arrangement in the first edition (1837) to the one at present 

 adopted, in which the general system of classification remains un- 

 altered from that of the fourth edition (1854), showing that he 

 evinces no aversion to change when the progress of science requires 

 it. This system is based on a comprehensive view of the characters 

 of mineral species, the pre-eminence being given to chemical, the 

 next place to crystallographic, the third to the different ph;^ical 

 characters. The following are the general subdivisions adopted in 

 the descriptive portion of the work : — 



I. Native Elements. 

 II. Sulphids, Telliirids, Selenids, Arsenids, Antimonids, Bismuthids. 

 III. Compounds of Chlorine, Bromine, Iodine. 

 IV. Fluorine Compounds. 

 V. Oxygen Compounds. 



I. Binary Oxygen Compounds. 



(1) Oxyds of Elements of Series I. ; (2) Of the Arsenic and 

 Sulphur Groups ; (3) Of the Carbon- Silicon Group. 

 11. Ternary Oxygen Compounds. 



1. Silicates, A. Anhydrous Silicates. 



(1) Unisilicates ; (2) Bisilicates ; (3) Subsilicates. 

 B. Hydrous Silicates. 



(1) Hydrous Silicates Section; (2) Zeolite Section ; 

 (3) Margarophyllite Section. 



2. Tantalates, Columbates. 



3. Phosphates. Arsenates, Antimonates. 



4. Borates. 



5. Tungstates, Molybdates, Vanadates. 



6. Chromates, Sulphates, TeUurates. 



7. Carbonates. 



8. Oxalates. 

 VI. Hydrocarbon Compounds. 



It is to be regretted that the author has not given the old and new 

 notation formulas under each mineral species, in order to meet the 

 requirements of the present transitional state of Chemical science. 



The formulas KgO and NajO (page xvi.) given to Potash and 

 Soda may be, perhaps, attributed to a slip of the pen, or to the con-. 



