Makch 15, 1907] 



SCIENCE 



417 



evening at the Hotel Colonial. The next 

 annual meeting will be held in Chicago. 



Professor Angelo Heilprin is president 

 for the year 1907. The complete list of 

 officers has already been published in 

 Science. 



Albert Peret Beigham, 

 Secretary 



SCIENTIFIC BOOKS 

 Petrogenesis. By Dr. C. Doeltek. Braun- 

 schweig, Briedr. Vieweg and Son. 1906. 

 Pp. xii + 261 ; 1 plate and 5 figures. 8vo. 

 Paper. 7 M. 



This is Volume XIII. of a series of mono- 

 graphs on natural history and mathematics 

 entitled 'Die Wissenschaft.' In it Professor 

 Doelter, of the University of Gratz, presents 

 an outline of the knowledge and theories con- 

 cerning rocks of all kinds. The comprehen- 

 sive treatise is put in the form of fourteen 

 chapters, the first ten of which deal with vol- 

 canic rocks, the last four with contact meta- 

 morphism, the formation of the crystalline 

 schists, sediments, and chemical precipitates. 

 One hundred and fifty pages are devoted to 

 the problems of igneous rocks, fifty-two to 

 those of the crystalline schists. 



The method of treatment is to present the 

 views of various geologists or petrographers 

 on different topics, sometimes with comments 

 and criticisms, sometimes without. The cita- 

 tions are many, but from the nature of the 

 task, perhaps, they are not always complete as 

 to number or entirely satisfactory as to sub- 

 stance in some instances. However, there is 

 a great fund of information for the student 

 and an abundance of valuable bibliographic 

 references. The scope of the work is so large 

 that it is not possible to review the book with 

 the thoroughness it deserves without a very 

 considerable expenditure of time and space. 

 And it may be suiEcient to point out the con- 

 tents of the several chapters in a general 

 manner. 



The first is devoted to a consideration of the 

 theories and observations concerning the in- 

 terior of the earth and the problem of vulcan- 



ism. The physics of the interior of the earth 

 is discussed and the observations of Barus 

 and Tammann with reference to melting 

 points and pressure are cited. The possible 

 source of molten magmas, and the causes and 

 mechanics of their eruption are considered, 

 including the role of vapors and the tempera- 

 ture of lavas. 



The second chapter treats of the forms of 

 volcanic rocks as conditioned by their solidifi- 

 cation on the surface of the earth or at some 

 depth below it, and also the infiuenee of vapors 

 upon the crystallization. The discussion of 

 laccolithic forms reveals a curious attitude 

 toward the original definition of the term by 

 Gilbert. In connection with the problem of 

 intrusion the views of Kjerulf and of Michel- 

 Levy are presented, and those in opposition 

 are credited chiefly to Brogger. Daly's theory 

 is also stated. 



The third chapter has to do with the struc- 

 ture (texture) of eruptive rocks. The por- 

 phyritic texture is discussed at length with 

 special reference to Fouque and Michel-Levy's 

 views and to those of Zirkel. A number of 

 petrographers are cited in connection with the 

 texture of phanerocrystalline rocks, chiefly 

 Brogger, Lane, Teall and Vogt. Spherulitic 

 texture receives considerable attention, the 

 views of Eosenbusch and of others being 

 noted. The question of the relation between 

 age and texture is considered, and the textural 

 and constitutional facies of rock bodies are 

 described. 



In the fourth chapter the relation between 

 the mineral composition and the chemical com- 

 position of igneous rocks is discussed. The 

 view of Lagorio, Vogt, Morozewicz and Id- 

 dings are commented on. The work of Osann 

 in correlating chemical analyses of rocks is 

 reviewed, and the methods of expressing the 

 chemical composition of rocks by means of 

 diagrams are described to some extent, espe' 

 cially those of Brogger and Becke. 



The fifth chapter deals with the problem of 

 the differentiation of magmas. Various the- 

 ories are set forth briefly and commented on. 

 The term is also applied to the crystallization 

 of minerals from molten magmas. Experi- 



