;>!>4 Scientific Intelligence. 



theories have boon put forward more recently to explain the phe- 

 nomenon. Ernst Gravis lias now made a very elaborate study 

 of the subject, and oomes to the conclusion that pure iron and 

 nickel are passive, and only become active from the presence of 

 hydrogen ions, which act as a catalytic agent. — Zeitschr. Physi- 

 hal. Chem., Ixxvii, 513. a. l. w. 



3. Combinations of Metallic Chlorides. — G. Herrmann has 

 studied the results of fusing together a large number of pairs of 

 metallic chlorides, as well as several pairs of bromides and iodides, 

 according to the methods used in the study of metallic alloys. 

 The salts used were PbCl a ,Cu 9 Cl a ,CdCl a ,FeCl 8 jSnCl 3 ,BiCl a and 

 MCI,, as well as PbBr a ,BiBr s ,Cu 2 Br a ,Cu 2 I a and Cdl„. Asa result 

 he has found no parallelism between the combinations of the metals 

 and their salts. Very few compounds of the salts were found, 

 for among 17 binary mixtures of chlorides there were 14 that 

 formed no compound. The three compounds formed were one 

 of PbCl 3 and BiCl 3 , the formula of which was not determined, 

 the compound Cu 2 Cl,.(FeCI 3 ), and also (Cu^ClJ^CdCl,. — Zeitschr. 

 Anorgan. Chem., Ixxi, 257. h. l. \v. 



4. New Method for the Separation of Cerium from other 

 Earths. — C. James and L A Pratt have found that potassium 

 bromate effects this separation in faintly acid or neutral solutions 

 upon boiling. To attain the proper neutralization of the small 

 quantity of free nitric acid present in the solution, they put in a 

 smooth lump of marble containing no crevices. Care is required 

 not to boil too long, but with proper precautions, and by i-epeat- 

 ing the separation, the authors obtained satiffaotory analytical 

 results, and found the method serviceable for the preparation of 

 pure cerium material. — Chem. News, civ, 61. h. l. w. 



5. The Composition of the Atmosphere after the Passage of 

 Halley's Comet. — G. Claude has found that the inert incondensi- 

 ble gases of the atmosphere show an unchanged specific gravity 

 of - 55 since the passage of Halley's comet, thus indicating 

 an unchanged proportion of neon and helium since that event. — 

 Ann. Ch. Phys., xx, 573. H. L. w. 



6. Modern Science Reader, with Special Reference to Chemis- 

 try, edited by Robert Montgomery Bird. 12mo, pp. 323. 

 New York, 1911 (The Macmillan Company). — This is a collec- 

 tion of popular essays and addresses gathered from various maga- 

 zines, journals, and encyclopedias. There are 27 of these 

 articles, most of them written by eminent authors on important 

 and interesting subjects. Some of the topics are The Diamond, 

 Waste Products, Explosives, Artificial Silk, Steel, Commercial 

 Oxygen, Plant-growth and Decay, Coal, Coal-tar Dyes, Artificial 

 Perfumes, Glass, Electro-chemistry, Yeast, Old and New Alchemy, 

 Radioactivity, Electronic Theory of Matter and Ether of Space. 



The book is well suited for giving the general reader an idea 

 of the recent views and achievements in chemistry, and it is a very 

 suitable work to place in the hands of the chemical student for 

 the purpose of arousing his interest and enthusiasm. h. l. w. 



