Ixxxiv GENEKAL SUMMARY OF SCIENTIEIC AND 



MINEKALOGY. 



By EDWAED S. DANA, Ph.D., 



Yalb College, New Haven. 



PUBLICATIONS, RESEARCHES, ETC. 



Several important works on Mineralogy have been published dur- 

 ing the year past. First among these stands Rammelsberg's " Hand- 

 book of Mineral Chemistry." This is a most valuable contribution 

 to the science, both on account of the high position which the au- 

 thor holds in the department, and also because it is the first com- 

 plete w^ork in which the chemical composition of minerals has been 

 discussed with sole reference to the j^rinciples of the New Chemistry. 

 It thus marks an era in the science, since hitherto the new formulas, 

 if given at all, have generally been made subordinate to those of the 

 old system. 



The " Physical Crystallography " of Professor Groth is also an im- 

 portant w^ork, since it gives a full and systematic, and yet very intel- 

 ligible discussion of the oj)tical characters of crystals, and the means 

 employed in their investigation. Other new works are the Crystal- 

 lographies of Klein and of Sadebeck ; the former discussing the 

 methods of calculation, and the latter the natural history of crystals, 

 their method of growth, and so on. The new (oth) Appendix by 

 Domeyko to his "Mineralogy" may also be mentioned ; the new min- 

 erals described in it are enumerated in the list which follows. 



Two mineralogical societies have recently been inaugurated in 

 England, one of which is called the " li k Z," after Professor Miller's 

 classical crystallographic symbols. Moreover, it has been announced 

 that a new journal, to be devoted exclusively to Mineralogy, is soon 

 to be commenced in Germany ; the design is to make it decidedly 

 cosmopolitan in its nature. 



In the department of Physical Mineralogy imj^ortant researches 

 have been jDublished by Hankel, Groth, and others. Hankel has 

 continued his investigations of the pyro-electrical properties of min- 

 erals, and has shown that these belong, not, as once supposed, to a 

 few hemihedral minerals alone, as tourmaline, but to all species in a 

 more or less decided degree. Moreover, he has shown that these 

 characters are determined, analogously to the optical properties, by 

 the symmetry of the crystalline form ; for instance, in a tetragonal 

 or hexagonal crystal the same kind of electricity is developed in 

 all lateral directions, that is, upon all prismatic planes, but the oj)po- 

 site kind at the extremities of the vertical axis. Groth has deter- 



