470 Revieius — Determinative Mineralogy Tables. 



with a discussion of diffusible substances, the geological media 

 which admit of diffusion, and the general characters of diffusion ; the 

 various types of structure are then treated in detail. The author 

 shows that diffusion has been responsible, moreover, for the alterations 

 that have sometimes occurred in ore-deposits, and for the formation of 

 certain pseudo-fossils, such as, for instance, the once famous Eozoon 

 canadense. Two indices, of names and subjects, which bring the book 

 to a close, add to its usefulness. 



V. — Determinative Mineralogy with Tables. By J". Volnet 

 Lewis. 8vo; pp. v + lSl, with 68 figures in the text. New 

 York: J. Wiley and Sons, 1913. Price 6«. &d. net. 



rpHIS book is designed to meet the needs of students and of mining 

 J_ engineers, and treats not only of minerals of economic importance 

 but also of many of the rarer species ; altogether 380 minerals are 

 included. 



In the text we find a brief account of the apparatus, reagents, and 

 methods to be used in ' wet ' and in ' dry ' tests, and of the principal 

 reactions of the elements. The simple forms of crystals are enumerated 

 and illustrated by fifty-seven figures of various minerals ; for an 

 explanation of the face-indices and for other details the reader is 

 referred to textbooks. There is a good glossary of technical terms, 

 and a table of the elements with their atomic weights. 



The tables are based very largely on those of Brush and Penfield, 

 but are modified and much condensed ; the relative importance of the 

 minerals is indicated by the type in which the names are printed. 

 The determinations are made to rest almost wholly on chemical tests, 

 and no mention is made of the optical properties of minerals. Tables 

 for the determination of rock-forming minerals, on the other hand, 

 commonly neglect the chemical and appeal only to the physical 

 properties. JSTow that the optical properties of so many minerals are 

 well established, and the use of the petrological microscope has 

 become so widespread, a combination of the two types of tables 

 should be quite possible, and any determinative mineralogy which 

 does not seek to combine the two must be considered a little behind 

 the times. 



W. C. S. 



VI. — Uniteb States Geological Survey. 



1. Bulletin 502. The Eagle River Region, South-Eastern Alaska. 

 By Adolph Knopf, pp. 61, with 3 figures in the text and 5 plates 

 (including 3 maps). 1912. 



THE area, which has been mapped on the 1 inch scale, embraces 

 a third of the Juneau gold belt of South-Eastern Alaska. 

 Three large glaciers come down from the Coast Range to within 

 100 feet of sea-level: they are shown to be retreating. There is 

 evidence that at one period the country was glaciated to 3,400 feet 

 above sea-level, the main ice-stream flowing south-east down the 

 Lynn Canal. The absence of hanging valleys supports the idea that 



