210 The American Geologist. March, 1892 
and they were therefore at once, and continually, in antagonism. Mean- 
time, as a common ground, on which they could compromise, the con- 
testants, by the necessity of intelligent discussion, fell mutually into the 
practice of using “trivial” names for all mineral species, and as time 
elapsed these names have become, at this day, the only ones inuse. The 
chemical classification, though not having any acceptable nomenclature 
based on it, has been strengthened by continual advance in the knowl- 
edye of the chemical composition of minerals, and in the philosophy of 
chemical combinations, until it is not too much to say that not any living 
author of systematic mineralogy, however strongly he may insist on 
physical characters, but discusses and depends largely on the composi- 
tion of minerals for the ultimate determination of their places in his 
scheme. In nomenclature, however, there has been little or no change. 
It is Dr. Hunt’s task to show that physical characters are but the ex- 
pression of chemical characters, and that they cannot be divorced, and 
that a “natural classification” must take cognizance of both. He has 
presented therefore a system which is both nutwral and chemical, and has 
covered it with a binomial Latin nomenclature which divides all the 
known minerals into classes, orders, genera and species. The classes 
and orders are determined essentially on chemical grounds. The genera 
are arranged from physical difference and resemblances, and the further 
definition of the species is the work of chemistry. All the mineral 
species are divided into four classes—Metallacer, Halidacexe, Oxydaceze 
and Pyrocaustacex. Order IV, in the class Metallacez, is thus com- 
posed : 
Order IV. PYRITINEA. 
Genus I. PyYRiveEs. 
Metallic sulphides H=> 5. v7 <5 
1:.Pyrites rutheneus: <... cs. 0.0... sclaw cack omer ee mlcieieacre Se niae rasa ee een Ese 
BB: ss VU SATIS oF 5 5.5 oss waco Tee ae a ae ee eacoteie te a).clo fa eT a 
3. £6 ~ s SCCUNGUS® . @.<). «ans.0 cc aisieaete Meee een ele ae Ue oie te CAR EReN 
4, te “cobalteus 0. =) 2. eo tess eons soe eianicle ne cruel ae ete ie RE igen 
Be 2 NICCOlLCUS 2:2, d0:5.504,c vowels ce eee tases Mens ehiec cee Cena. 
6. s ' - Cuprocobaltens.... 2 acc na coon ae ete ere eae sae CLO beter 
We Chromicus.. sesh. ji. 2s see eet odes eee cane ae D AULDECe Eas 
The work, with its accompanying discussions of chemical philosophy 
and mineral physiology, is the culminating result of a life-long study, 
We consider it Dr. Hunt’s chef @’ wurre, and the most important addition 
which American authors have made to the science of mineralogy. Dr. 
Dana’s great volume, System of Mineralogy, is a vast compilation, ar- 
ranged under a loose chemical classification, but makes no attempt to 
justify its philosophy—if it may be said to have any. On the contrary, 
Dr. Hunt’s work marks an epoch in the science, as it discusses from new 
standpoints and readjusts, in accordance with the latest chemical philos- 
ophy, all the discordant material, and establishesa fundamental skeleton 
on which the future may build a symmetrical structure in mineralogy. 
It seems to answer to mineralogy as the classification of Linnzeus does 
to botany. 
Guide to Baltimore, with an Account of the Geology of its Environs. 
GEORGE H. WriuiAMs. Prepared for the American Institute of Mining 
