Quantitative Classification 
of Igneous Rocks ih An Improvement 
Based on Chemical and Mineral Characters That P ays forthe Machine 
With an Introductory Review of the Devel- - 
opment of Systematic Petrography 
in the Nineteenth Century 
By WHITMAN Cross, JosEPH P. Ippines, Louis V. Pirs- 
son, and Henry S. WASHINGTON 
HE BOOK presents in detail the new system of classi- 
fication and nomenclature proposed by the authors, It 
contains a series of tables to aid in the calculation of 
mineral and chemical! compositions of rocks, and a glossary 
of the new terms employed in the nomenclature. Having 
traced the development of petrography during the past 
century, the authors discuss the defects of the present system 
of classification, the basis on which a proper classification 
must be made, and the construction of the system proposed, : 
The new nomenclature is then presented in full, including The above soa Ba aaie stalementiof, Ei seca rendered by 
magmatic and rock names; and the last part of the book is e bs cape Sharan 
devoted to methods of calculation, the tables, and the R Y t T it 
glossary. The book answers a need widely felt among eming on ypewrl er 
petrologists in the last few years for a new petrographic On the Model 10 Remington the starting point of every line of 
system into which could be fitted the recent large additions Hat coved by cliditaiag Kad adie etisichite core pes 
to our knowledge of rocks. 40 seconds per letter and envelope. Fhis average has been deter- 
mined by numerous comparative ee Tec a TS Rate 
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