Petrological Abstracts and Reviews 



Edited by ALBERT JOHANNSEN 



Announcement. — With this number of the Journal a beginning is made 

 in the publication of a series of abstracts and reviews of petrographical 

 papers which it is hoped may be continued in each issue in the future. 

 Whether this will be possible or not will depend largely upon the co-opera- 

 tion of petrologists. With the increasing number of petrographical descrip- 

 tions, reading and reviewing all articles has become a work too great for 

 one man to accomplish in his spare time, and it is necessary to ask the 

 assistance of all petrographers who are interested in keeping these abstracts 

 up to date. This work was begun too late to cover all the recent literature, 

 but great interest has been shown by the few petrographers who have been 

 consulted, and much aid has been promised for future numbers. It is 

 hoped that authors will themselves send in short summaries of their papers, 

 promptly upon publication, giving reference to publication, volume, etc., 

 as in the abstracts here published. It is especially desirable that new 

 analyses, new methods of determination, and new instruments, be fully 

 described. Summaries and separates for abstracts may be sent to 

 Albert Johaniisen, Walker Museum, The University of Chicago. 



Barbier, Ph. " Sur un caractere chimique differentiel des orthoses 

 et des microclines," Comptes Rendus de VAcademie des Sciences, 

 1908, CXLVI, 1330. 

 Spectroscopic analysis of the chlorides of the bases extracted from twenty- 

 five orthoclases and twenty microclines shows that the orthoclases invariably 

 contain small quantities of either lithium or rubidium, or both together, 

 while the microclines contain neither. The author concludes that ortho- 

 clase constitutes a definite species characterized by monoclinic form and 

 the presence of small quantities of lithium and rubidium, and that it there- 

 fore can be distinguished chemically from microcline. 



F. C. Calkins 

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