214 Scientific Intelligence. 



It is to be questioned if it is worth while to include in an 

 elementary book a brief and therefore necessarily unsatisfactory 

 treatment of the difficult subject of the optical properties of 

 crystals. The determinative tables which are based upon the 

 physical properties of minerals seem to be unnecessarily bulky 

 and consequently difficult to use. w. e. f. 



6. The Ore Deposits of Utah; by B. S. Butler, G. F. Lough- 

 LiN, V. C. Heikes and Others. U. S. Geol. Surv., Prof. Paper 

 111, 1920. Pp. 672, 74 figs., 57 pis.— This is the second profes- 

 sional paper to appear detailing the geology and ore deposits of 

 a single state. In 1910 a similar report on New Mexico was pub- 

 lished and reports dealing with other states are in preparation. 

 While a large part of the material in the present volume has 

 been previously published in other reports, the gathering of it 

 together in a condensed form into a single volume and including 

 w^ith it a general study of the ore deposits of the state makes it a 

 most valuable addition to the literature of economic geology. 

 From this study of the state as a whole has come the following 

 important generalization. 



The value of an ore deposit found in connection with an 

 igneous stock will be largely determined by the amount of erosion 

 the stock has undergone. Deposits around the apex of stocks are 

 larger and more valuable than those located at greater depths in 

 and around the stock. Cojisequently stocks that have been least 

 eroded will be more favorable as locations of ore deposits. The 

 amount of erosion of a given stock can be estimated from the 

 chemical character of the igneous rocks exposed. The lower 

 portion of the stock is uniformly more siliceous, the character of 

 the rock changing from monzonite and diorite at the apex to 

 granodiorite and granite at greater depths. w. e. f. 



Obituary. 



Dr. Henry A. Bumstead, professor of physics and director of 

 the Sloane Physical Laboratory at Yale University, and for the 

 past half-year on leave from the University as Chairman of the 

 National Research Council of Washington, D. C, died suddenly 

 on the train on the night of December 31 while returning to 

 Washington from Chicago. A notice is deferred until a later 

 number. 



Sir William de Wiveleslie Abney, the gifted English astron- 

 omer, died on December 2 at the age of seventy-seven years. 



Percival Spencer Umfreville died at Harpenden, England, 

 at the age of sixty-two years. His chief work was in physical 

 chemistry, dealing with the phenomena concerned in the forma- 

 tion and solution of salts. 



William Arthur Howard, research fellow in the Imperial 

 College of Science and Technology, died suddenly as the result of 

 a laboratory accident on December 6 at the age of twenty-six 

 years. 



Dr. Yves Delage, professor of zoology in the University of 

 Paris, died recently at the age of sixty-six years. 



