REVIEWS 313 



and petrographers to the accompanying plates reproduced from this 

 remarkable monograph, and to the importance of careful study of the 

 results of such experimentation in connection with research in the field. 

 Dr. Morozewicz has written the results of his elaborate synthetic stud- 

 ies in most compact and readable form, the work being contained in 

 225 pages systematically arranged, well indexed, with each chapter 

 carefully summarized as well as the whole work. He has shown that 

 the synthetic production of rock-making minerals is possible under 

 conditions attainable in any of our large cities, and his work should be 

 a stimulus to further endeavor of the same sort. Analytical work alone 

 is no more capable of solving many difficult problems connected with 

 the origin of the igneous rocks and of ore deposits than are the meth- 

 ods of microscopical petrography. Morozewicz has shown that the 

 same synthetic treatment is applicable to the chemistry of the silicates 

 that has been used for years in the case of the hydro-carbon com- 

 pounds. 



T. A. Jaggar, Jr. 

 Cambridge, Mass. 



PLATE III. 



Fig. 1 . Enstatite-basalt, first stage : olivine, enstatite, monoclinic pyrox- 

 ene, glassy groundmass ; enlarged X 60. 



Fig. 2. Enstatite-basalt, second stage ; micro-porphyritic structure : large 

 enstatite crystals in a groundmass which consists of augite, labradorite, oli- 

 vine, and magnetite ; enlarged X 60. 



Fig. 3. Normal basalt, first stage ; augite and magnetite microlites in 

 glassy groundmass (hyalopilitic) ; enlarged X 60. 



Fig. 4. Normal basalt, second stage : great augite masses with inclusions 

 of olivine and magnetite ; brown groundmass ; enlarged X 60. 



Fig. 5. Enstatite-basalt: olivine concretions seen below; enlarged X 60. 



Fig. 6. Basalt without olivine, ophitic structure : long plagioclase prisms 

 with augite in the interspaces ; black grains of spinel and magnetite ; 

 enlarged X 60. 



PLATE IV. 



Fig. 1. Anorthite-nepheline magma: large anorthite crystals with cleav- 

 age cracks and multiple twinning ; in the groundmass occurs nepheline, 

 arborescent magnetite forms, etc.; ordinary light, enlarged X 15. 



Fig. 2. The same between crossed nicols in polarized light. 



