Revieivs — J. P. Iddings — Rock Minerals, 571 



tracts of ice in Arctic and Antarctic regions, and the physical features 

 of the two areas are contrasted. In the one we have a polar sea 

 surrounded hy an irregular chain of land-masses, in the other a high 

 continent massed near the South Pole. Excellent views are reproduced 

 of the glacial features in Greenland, after Nathorst, Chamberlin, 

 Trolle, and others. Accounts are given of the wind-drifted snow in 

 this 'Arctic Sahara', of the various streams superglacial, englacial, 

 and subglacial, of ice-dammed lakes, of ' submarine wells ' or 

 whirlpools of fresh water that rise at the heads of some of the fjords, 

 and of the methods of discharge of bergs from the ice-front. 



Finally, the volume includes good descriptions concerning what is 

 known of the Antarctic Continent and its sea-ice girdle, of the 

 marginal shelf-ice or so-called ' barrier ' ice, and of the great inland 

 ice-sheet, subjects well illustrated by views after von Drygalski, 

 Scott, Shackleton, and others. 



III. — Rock Minerals : their Chemical and Physical Characters 

 and their Determination in Thin Sections. By Joseph P. 

 Iddings. Second Edition. 8vo ; pp. xiii + 617, 500 figures, and 

 one coloured plate ; cloth. New York, John Wiley and Sons ; 

 London, Chapman & Hall, Ltd. ; 1911. Price $5. 



IT is a sign of the great utility and consequent demand for this valuable 

 technical treatise that within five years it has been necessary to 

 issue a second edition. This edition differs from the first mainly in 

 its greater bulk, a feature necessitated by the remarkable progress 

 made in various departments of mineralogical science. The introductory 

 portion, containing a general account of physical and optical characters, 

 remains practically without change ; but a very clear and not too 

 laboured account of pleochroic haloes has been added. In this are 

 summarized the results obtained by Miigge, Joly, and Eletcher, and 

 a table of measurements by the two latter authors is given. 



In the section devoted to the description of minerals important 

 additions have been made with respect to nineteen species and seven 

 groups not treated of in the previous issue of this work. Among the 

 rare and recently discovered minerals concerning which particulars are 

 given may be noted carnegieite and rhonite. The groups referred to 

 are designated respectively by the names of the minerals melanocerite, 

 columbite, samarskite, seschenite, aragonite, barite, and triphyllite. 

 The systematization of hitherto un associated details given therein will 

 undoubtedly be of considerable value to students. In the interests of 

 terminological accuracy it might have been well in the description of 

 minerals to substitute the word alstonite for bromlite, the latter 

 designation owing its origin to a misspelling of the name of the 

 locality Brownley Hill. 



An excellent birefringence diagram has been added to the tables and 

 plate of interference colours at the end of the book. There can be no 

 doubt that this volume, brought up to date as it is with scrupulous 

 accuracy and attention to the requirements of students of petrography, 

 cannot fail fully to maintain its high position among the premier 

 treatises on mineralogical science. 



