Geology. 307 



No. 195. Underground conditions in oil fields ; \>y A. W. 

 Ambrose. 296 pp., 11 pis., 52 figs. 



Xo. 198. Regulation of explosives in the United States, with 

 especial reference to the administration of the Explosives Act of 

 October 6, 1917, by the Bureau of Mines; by C. E. Munroe. 

 45 pp. 



No. 205. Flotation tests of Idaho ores, by C. T. Wright, J. G. 

 Parmelee, and J. T. Norton. 70 pp., 8 pis., 1 fig. 



No. 206. Petroleum laws of all America; by J. W. Thompson. 

 448 pp. (40 cents.) 



Prices are given for the last received bulletins. 



7. Metamorphism in Meteorites. — A recent number of the 

 Bulletin of the Geological Society of America (volume 32, page 

 395), contains an article by Dr. G. P. Merrill of the National 

 Museum on the origin and structure of chondritic meteorites 

 which is worthy of note here. He thinks to show that the 

 chondritic meteorites are all of a volcanic and tufaceous origin 

 and their varying textural peculiarities due to metamorphism in 

 which both heat and pressure have had a part. It is pointed out 

 that the most perfect chondroidal forms are found in those 

 meteorites the fragmental nature of which is the most apparent, 

 and that they are less perfect in the crystalline forms. The clear 

 interstitial glassy material, sometimes isotropic and sometimes 

 doubly refracting, he considers, as have others before him, to be 

 feldspathic, but argues that it is due to metamorphism and to 

 have been the last mineral to congeal, representing the closing act 

 in the series of changes through which the stone has passed. The 

 dark glassy material sometimes surrounding the chondrules, in 

 stones of the Parnallee type, is considered secondary, the result 

 of a partial refusion of a fine interstitial material. The metal is 

 also of secondary origin, this conclusion being based upon its dis- 

 tribution and manner of enwrapping certain of the fragments 

 and chondrules, as would occur in the case of secondary precipi- 

 tation, and also from the fact that in stones of the Cumberland 

 Falls type metal of two distinct generations can be readily traced. 



The idea of the author seems to be that this study having refer- 

 ence to the original structures of the stony meteorites and the 

 secondary changes which they have undergone may throw some 

 light upon the sources from which they have been derived and 

 their subsequent wanderings. 



III. Miscellaneous Scientific Intelligence, 



1. Carnegie Institution of Washington. Year Book, No. 20, 

 1921. Pp. xxii, 475. Washington, February, 1922.— The twen- 

 tieth year of the lines of research conducted by the Carnegie Insti- 

 tution is an important point in its remarkable history. Hardly 



