88 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 

 I. Chemistry and Physics. 



1. A Revision of the Atomic Weight of Aluminium. — Theo- 

 dore AV. Richards and Henry Krepelka have published a pre- 

 liminary paper upon the atomic weight of aluminium, giving the 

 results of four determinations based upon the ratio of aluminium 

 bromide to the silver required to combine with the bromine in it. 

 The preparation and purification of the aluminium bromide was 

 carried out in a most ingenious and evidently perfectly effective 

 apparatus, and all the details and whole process were carried out 

 with the greatest care and skill, such as is always shown in the 

 atomic weight determinations directed b}^ Richards. The results, 

 based upon bromine as 79.916 and silver as 107.88, are 26.967, 

 26.965, 26.956 and 26.951. The average is 26.960, while the re- 

 sult calculated from the total weights emploj^ed — nearly sixteen 

 grams of the bromide and over nineteen grams of silver — is 

 26.963. The agreement of the results is remarkably close. 



The usually accepted atomic weight of aluminium, 27.1, is 

 based chiefly on the work of Mallet, published in 1880. This 

 work has been highly regarded because results by three distinct 

 methods agreed closely, so that the more recent result, in 1897, of 

 Thomsen, 26.99, based upon a single method, was not accepted 

 by the international committee. The new result is not far from 

 that of Thomsen, and it appears probable that future work will 

 not change it to any considerable extent. It seems certain, there- 

 fore, that the atomic weight of aluminium is slightly less than 27, 

 and this is a matter of interest to those who are studying the 

 structure of atoms and their numerical relations. — Jour. Amer. 

 Chem. Soc, 42, 2221. h. l. w. 



2. The Chemists' Year Book, 1920; Edited by F. W. Atack. 

 Fifth edition, 16mo, pp. 1136. Two volumes. New York, 1920 

 (Longmans, Green & Co. Price .$7.00 net). — The appearance 

 in 1915 of the first edition of this work of English origin was due 

 to the cutting off' of the supply of German pocket-books which 

 had been previously used by many chemists and other scientific 

 workers. As it appears in its fifth year the book shows a vast 

 amount of useful, well-arranged information, and it may be re- 

 garded as an improvement upon the German hand-books as well 

 as a further convenience in its language to English-speaking 

 chemists. It is well printed upon very thin paper of excellent 

 quality so that it is very legible, while its bulk is small in com- 

 parison with its large number of pages. There are many tables, 

 among which may be mentioned those giving gravimetric factors, 

 five figure logarithms, specific gravities, solubilities, and the very 

 extensive ones dealing with the properties of inorganic and of 

 organic substances, and of minerals. There are also tables re- 



