146 Scientific Intelligence. 



of oxygen. A solution containing 10 -6 , that is, one millionth of 

 copper, gave immediately a rose tint changing to bright red in a 

 few seconds. At a dilution of 10~ 7 the color did not appear 

 until after 10 or 20 seconds, while at 10~ 8 , the limit, a very pale 

 color appeared after a few minutes which could be easily seen by 

 comparison with a blank containing no copper. 



The authors have compared this test with others, including the 

 one with hematoxylin described in this journal in 1906 by Brad- 

 ley, and they conclude that it is the most delicate of all. They 

 give warning that certain supplies of distilled water and many 

 so-called chemically pure reagents contain appreciable amounts 

 of copper when subjected to this test.- — Comptes Rendus, 173, 

 1082. h. l. w. 



3. Lehrbuch der Eisenhiitfenkunde; von Bernhard Osann. 

 Zweiter Band : Erzugung und Eigenschaften des schmiedbaren 

 Eisens. 8vo, pp. 794. Leipsic, 1921 (Verlag von Wilhelm Engel- 

 mann). — This text-book on the production and properties of 

 wrought iron and steel appears to be a most excellent treatise 

 that can be highly recommended to those who read German and 

 are interested in the subject. It presents many tables of statis- 

 tics, explains the historical development of the important pro- 

 cesses, and give a very complete and satisfactory account of the 

 present condition of the art from both the theoretical and prac- 

 tical points of view. 



The book is copiously supplied with no less than 651 illustra- 

 tions ' 'in the text ' ' and 10 larger tables or plates. A large pro- 

 portion of the figures are admirable sectional drawings of 

 apparatus, showing the details of construction. 



It should be noticed that the operations which give the final 

 form to the metal, such as rolling, drawing, hammering and 

 casting, are not treated in the book on account of the necessity 

 for limiting its size. Theoretical metallography is only very 

 briefly discussed, although the practical subjects of hardening, 

 cementing, ignition, etc., are thoroughly treated. h. l. w. 



4. Mining Physics and Chemistry ; by Z. W. Whitaker. 

 12mo, pp. XII and 268. New York, 1921 (Longmans, Green & 

 Co. Price, $3.00). — The author of this text-book is a Certified 

 Colliery Manager, and Lecturer in the Mining Department, Uni- 

 versity College, Nottingham, England. The book presents the 

 simpler fundamental principles and facts of physics and chem- 

 istry, with particular attention to topics of special interest in con- 

 nection with coal-mining. For instance, considerable attention 

 is paid to pumps, and the subject of mine gases is rather elabor- 

 ately treated in connection with the detection of explosive mix- 

 tures and the physiological effects of C0 2 and C0 4 . As another 

 example the discussion of explosives and their employment in 

 the mining of coal is quite elaborate. 





