MINERALOGY IX 1886. 



By Edwaud S. Daxa, FaJe College, Xew Haven, Conn. 



GrENERAL WORKS ON MINERALOaY. 



The list of miueralogical text-books Las received an imi)ortaiit addi- 

 tion during the past year in the Lehrbuch der Mineralogie* of Bauer. 

 It is a work of nearly six hundred pages, and covers about tbe same 

 ground as the mineralogy of Tschermak, noted in the reports of 1884 

 and 1885. It is especially strong in the chapters on physical mine- 

 ralogy, and here gives much valuable matter that has not hitherto 

 found its place into the text-books. The descriptions of species, 

 though necessarily brief, give all that the ordinary student requires. 

 A work of great magnitude and importance is the Index der Krys- 

 tallformen, by Goldschmidt, the first volume of which was completed 

 in 1886. This work, which, when completed, will make three large 

 volumes of six hundred pages ea(;h, i)roposes to give complete lists 

 of all the crystalline forms identified on the crystals of every species, 

 with the literature, the symbols of different authors, and so on. The 

 author has started out with the plan of putting this material in the 

 form which he regards as most useful foe a discussion of the mathemat- 

 ical relations of the forces involved in the making of the crystal. 

 With this end in view he has developed a new system of symbols, and 

 adoi)ts a new jilan in regard to the choice of the i)Osition of a crystal, 

 taking that one which gives the simplest symbols and lends itself most 

 readily to the representation of the forms on a plane of projection. This 

 system of symbols is worked out with admiral thoroughness, both with 

 respect to the methods of calculation adapted to it, and its relations 

 to the other systems of symbols which have been employed from the 

 time of Hatty down. The unity of the work, therefore, is a iirominent 

 feature, and the details of the plan have evidently been developed with 

 great care. The practical student of minerals, however, will be in- 

 clined, at least at first, to regret the introduction of a new series of 

 symbols, and he will question further whether the reasons given are 

 sufficient to justify placing the crystals of the majority of the species 

 in a new position, and in general not the one Avhich is most convenient 

 for the study of the crystal itself or for its comparison with those of 

 related species. ^ 



* For full titles of works mentioned see the Bibliography at the end of the chapter, 

 H. Mis. 600 29 449 



