576 Scientific Intelligence. 



carbonyl, which consists in using carbon monoxide under press- 

 ure at a correspondingly higher temperature. A pressure of 100 

 atmospheres was used for the carbon monoxide, and under this 

 condition a combination with finely divided metallic cobalt took 

 place between 150 and 200° C. The cobalt carbonyl is a very vola- 

 tile substance which condenses in the form of large orange crystals 

 when the vapor is cooled by ice. The compound is very unstable, 

 melting with decomposition at about 42 to 46° C. It is gradually 

 decomposed in air, yielding a deep violet substance which has 

 not yet been investigated. — Chem. JVews, xcviii, 165. h. l. w. 



4. Cyanide Processes ;hy E. B. Wilson. 12mo, pp. 249. New 

 York, 1908 (John Wiley & Sons). — This is the fourth edition, 

 revised and enlarged, of a well-known treatise. Owing to the 

 recent improvements in cyanide practice, especially in the treat- 

 ment of slimes, the author has added a chapter giving the latest 

 methods for treating such material. The book, as has been the 

 case with previous editions, deals with the theories and facts con- 

 nected with the processes, without giving details of the construc- 

 tion of the plant and machinery. h. l. w. 



5. Magnetic Rotation of Electric Discharge. — Professor D. N. 

 Mallik has studied the old experiment of De La Rive, which con- 

 sists in causing the rotation of an electrified discharge around 

 the pole of a magnet, and classifies three stages : showery, band, 

 and glow. The discharge rotates under the influence of the mag- 

 netic field, only when it is in the form of a band over a range of 

 pressure depending on the nature of the gas or vapor in the tube 

 through which the discharge passes, the E. M. F. producing the 

 discharge and the distance between the electrodes. In air, and 

 probably in all gases, the angular velocity of rotation is propor- 

 tional to the E. M. F. producing the discharge, and increases as 

 the spark length decreases. Professor Mallik also analyzes the 

 conditions of pressure and temperature. — Phil. Mag., Oct., 1908, 

 pp. 531-550. j. t. 



6. A Directive System of Wireless Telegraphy. — E. Bellini 

 and A. Tosi describe such a system which depends upon a method 

 of orienting the sending coils of a transformer with respect to 

 the antennse. They give a test of their method, carried out 

 between the stations of Dieppe and Havre. On turning what they 

 term their radiogiometer in the direction of Havre, reception of 

 messages was effected. On turning the pointer of this instru- 

 ment to 180° this reception ceased entirely. The authors point 

 out the strategical advantage of their system. — Phil. Mag., Oct., 

 1908, pp. 638-657. J. T. 



7. Positive Pays. — Professor J. J. Thomson, in an extended 

 article on this subject, reviews and corroborates the results of 

 Villard (Comptes Rendus, cxliii, p. 673, 1906) on what is termed 

 retrograde rays : that is, positive rays which proceed from the 

 cathode and travel against the positive rays, proceeding from the 

 anode. Professor Thomson also gives a theory of the method by 

 means of which these retrograde rays obtain their velocity. The 



