276 Scientific Intelligence. 



prominence is given to the 'normal group' under the successive 

 systems, Unit is, to the group which is relatively of most common 

 occurrence and which shows the highest degree of symmetry. 

 The methods of Miller are followed as regards the indices of the 

 different forms and the mathematical calculations. 



In the chapters on Physical and Chemical Mineralogy, the plan 

 of the former edition is retained of presenting somewhat fully 

 the elementary principles of the science upon which the mineral 

 characters depend; this is particularly true in the department of 

 optics. The effort has been made to give the student the means 

 of becoming practically familiar with all the modern methods of 

 investigation now commonly applied. Especial attention is, 

 therefore, given to the optical properties of crystals as revealed 

 by the microscope. Further, frequent references are introduced 

 to important papers on the different subjects discussed, in order 

 to direct the student's attention to the original literature. 



The descriptive part of the volume is essentially an abridg- 

 ment of the sixth edition of Dana's System of Mineralogy, pre- 

 pared by the author (1892). To this work (and future Appen- 

 dices) the student is, therefore, referred for fuller descriptions of 

 the crystallographic and optical properties of species, for analyses, 

 lists of localities, etc., also for the authorities for data here 

 quoted. In certain directions, however, the work has been 

 expanded when the interests of the student have seemed to 

 demand it; for example, in the statement of the characters of 

 the various isomorphous groups. 



6. 1? or dans la Nature ; by E. Cumenge and F. Robellaz. 

 Premier Fascicule, 106 pp., Paris, 1898. (P. Vicq-Dunod et Cie, 

 Editeurs.) — This is a work of quite unusual character, in that it 

 presents the subject of the occurrence of gold in nature in com- 

 plete form from the various mineralogical, chemical, and geologi- 

 cal standpoints. We have first a description of the crystalliza- 

 tion of gold, then a summary of the composition of that from 

 the different localities, and a general description of the occurrence 

 of associated minerals. Following this is a brief chapter on the 

 various minerals containing gold in nature and then an excellent 

 digest of the gold regions in the different parts of the world. It 

 is stated that the next fascicule will take up the subject of the 

 distribution of gold in the geological formations, ancient and 

 modern, auriferous gravels, and auriferous conglomerates, with a 

 special study of the Transvaal. The work as thus far published 

 can be highly commended, and in its complete form will doubtless 

 prove of much value. 



A series of thirteen excellent plates, which represent natural 

 specimens of exceptional beauty of crystallization and interest of 

 form, deserves very high praise. 



