October 6, 1911] 



SCIENCE 



447 



key to the solution of the problems in the 

 physical chemistry of geology lies in the de- 

 termination of the conditions of equilibrium 

 of each set of actions, or states of existence, 

 of the factors under discussion; and further 

 that he has attempted rather to stimulate in- 

 terest in this branch of geology than to pro- 

 vide a complete exposition of the subject. It 

 appears that this attempt is eminently suc- 

 cessful, and that students of geology and 

 petrology will be greatly benefited by this 

 presentation of the principles in question. 



The book consists of 10 chapters dealing 

 with (1) Equilibrium between the Crystal- 

 line and Amorphous States; (2) Equilibrium 

 as Influenced by Viscosity; (3) DifEusion as 

 a Factor of Equilibrium; (4) Surface Ten- 

 sion as a Factor of Equilibrium; (5) Vapor 

 Pressure as a Factor of Equilibrium; (6) 

 Equilibrium Conditions of Polymorphous 

 Forms; (Y) Equilibrium in Solutions; 

 (8) The Eutectic Theory; (9) The Theory of 

 Solid Solutions Applied to Geological Prob- 

 lems; (10) On the Conditions of Chemical 

 Equilibrium in Geology. 



"Without undertaking to give a synopsis of 

 the contents of these chapters, or to do more 

 than express approval of the method of treat- 

 ment with a recommendation that they be 

 carefully studied by those interested in the 

 subject, attention may be called to several in- 

 stances in which the fallibility of the litera- 

 ture relied upon by the author may be illus- 

 trated, or to instances where it has been mis- 

 interpreted. In the Chapter on Viscosity the 

 observation of Barus on the combination of 

 water and glass at temperatures between 185° 

 and 200° C. is cited, and the impression is 

 given that it is an operation of unlimited 

 applicability to all glasses. Whereas Barus 

 subsequently found that other commercial 

 glass did not combine with water under any 

 conditions which his apparatus was able to 

 impose. The general conclusion stated by Mr. 

 Elsden as to the efEect of water in solution in 

 silicate magmas in reducing viscosity is, 

 nevertheless, correct, as other observations 

 have shown. 



In connection with surface tension and its 

 explanation of the growth of larger crystals 

 at the expense of smaller ones the author has 

 confused his citations by referring to a de- 

 scription of the obsidian at Obsidian Clifi, 

 Y. N. P., by the reviewer, as containing a 

 supposed application of the principle to the 

 weathering of the laminated rock. There is 

 no reference to weathering in the paper men- 

 tioned, and its author never entertained any 

 such ideas as those implied in the comment 

 by Mr. Elsden. 



In the discussion of crystallizations in 

 metastable and labile states of solution it is 

 quite evident that the author is not relying 

 on his own knowledge of rocks, but has been 

 misled by the dogma of " first and second 

 generations of crystals," when he states that 

 " while the metastable state persists small 

 crystals could not be produced," for nothing 

 is commoner than seriate porphyritic fabric 

 in igneous rocks, and the presence of various 

 sized crystals of the same kind of mineral. 

 His treatment of the subject of crystallization 

 is not so satisfactory as that of other portions 

 of his subject. And in the discussion of the 

 amphibole and pyroxene series the lack of 

 appreciation of the chemical phase of the 

 problem is apparent. 



Aside from these criticisms the book is a 

 valuable contribution to the literature of 

 geology, and should be studied by all who de- 

 sire to understand the bearing of physical 

 chemistry on the problem of the formation 

 and alteration of minerals and rocks. 



J. P. Iddings 



THE RELATION BETWEEN THE COLORA- 

 TION AND THE BATHYMETEICAL 

 DISTRIBUTION OF THE 

 CYCLOGASTEEIDM 



In a recent article in Science' Dr. H. B. 

 Bigelow gives a resume of a preliminary re- 

 port' by Dr. Johan Hjort on the results of the 



iJuly 7, 1911. 



^ Geographical Journal, Vol. 37, 1911, pp. 349- 

 377, 500-523. Not seen by the writer. 



