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XXIV. Notices respecting JS r ew Books. 



Systematic Mineralogy, based on a Natural Classification. By T. S. 

 Hunt, M.A., LL.D. 8vo. Pages i-xvii, and 1-391. Scientific 

 Publishing Co. : New York, 1891. 

 T^NDEAVGUBINGr to determine a Natural System in Minera- 

 -■-^ logy, the author of this work carefully studied the minera- 

 logical systems proposed by Berzelius (1815-24), Werner (1817), 

 Mohs (1822-24), Shepard (1835-44), Jameson (1820), Breithaup 

 (1836-46), Weisbach (1875-84), Eammelsberg (1841), Dana 

 (1837-82), Naumann (1849 ?-85), G-roth (1882). The chief 

 features of these systems are carefully defined, and the author 

 observes that at present " the results of the chemical analysis of 

 species are generally considered as of paramount significance ; 

 while hardness, specific gravity, crystalline form, and optical 

 characters assume a secondary value in classification, and are 

 regarded as important chiefly in connexion with determinative 

 mineralogy. The conception of a true natural method, which, 

 although but partially understood, was at the basis of the system 

 of Mohs, has been generally lost sight of ; the order which the 

 naturalist finds in the organic is no longer apparent in the inorganic 

 world, as presented in modern mineralogical text-books ; and this 

 state of things has contributed not a little to the comparative 

 ueglect into which systematic mineralogy has of late years fallen." 



. ; " There exist, in fact, inherent and necessary relations 



between the physical characters and the chemical constitution of 

 inorganic bodies, which serve to unite and reconcile the natural- 

 historical and the chemical methods in mineralogy. A physico- 

 chemical study of the mineral kingdom, having in view these 

 relations, will enable us, while remaining faithful to the traditions 

 of AVerner and of Mohs, to frame a classification which it is 

 believed will merit the title of a Natural System in Mineralogy." 



The chemical and natural-history methods being both defective, 

 Dr. T. S. Hunt has endeavoured to reconcile the two, observing a 

 strict conformity to chemical principles, and at the same time 

 retaining all that is valuable in the natural-history method. 

 " Chemical and physical characters (he observes) are really depen- 

 dent on each other, and present two aspects of the same problem, 

 which can never be solved but by the consideration of both. 

 Differences in specific gravity between two or more solid species 

 do not become intelligible until we know the equivalent weights 

 of these species as deduced from chemical investigation. It is not 

 the specific gravity itself, but the relation of this to the equivalent 

 weight which must be taken into account." Hence in the intro- 

 ductory chapters the author has explained "in a somewhat 

 elementary manner such principles of physics and chemistry as 

 seem necessary for a clear understanding of this relation. The 

 nature of chemical change, the connexions between gases, liquids, 

 and solids, the periodic law, the principles of progressive series 



