22 SCIENCE PROGRESS 



together of such models we have the explanation of certain facts 

 of crystallography. Not only so, but Thomson, moving away 

 from the question of spectroscopic evidence for the moment, 

 introduces very interesting computations for such humdrum 

 physical properties as bulk-modulus, latent heat, surface 

 tension, and compressibility. He also makes considerable 

 appeal to the evidence supplied by his own special experi- 

 mental method of investigation, viz. positive ray analysis. 

 In certain particulars, notably in the high stability of an 

 " octet " of electrons, his models resemble those of the Lewis- 

 Langmuir theory, but decided differences arise in the treat- 

 ment of the long periods. In addition to his recently published 

 papers he has addressed the Royal Institution at various times, 

 and gave a very interesting course of lectures on " Atoms, 

 Molecules, and Chemistry " at University College, London, 

 during last May.* 



References 



I. Langmuir, /. Amer. Chem. Soc, 41, pp. 868, 1543 (1919) ; 

 42, p. 274 (1920). 



J. J. Thomson, Phil. Mag., April 19 19, March 1921, April 

 1922. 



The recently published " Series Spectra " of N. R. Campbell 

 (Cambridge University Preess, los. 6d.) gives an admirable 

 account of the development of Bohr's ideas. 



An excellect report on the atomic structure problem has been 

 prepared for the National Academy of Sciences of America by 

 the committee of their National Research Council. It is pub- 

 lished as Bulletin No. 14 of the National Research Council, 

 and can be obtained for 75 cents from their offices in Washing- 

 ton, D.C. 



PHYSICAL CHEMISTRY. By W. E. Garner, M.Sc. University College, 

 London. 



lonisation and Chemical Reaction. — ^The electron theory of 

 chemical valency, which is being developed so vigorously at 

 the present time by (Sir) J. J. Thomson, Lewis, Langmuir, and 

 with special reference to organic chemistry by Fry, Lapworth, 

 Robinson, and many others, has directed attention to the 

 possibility of electrical phenomena occurring during chemical 

 change. It is well known that at high temperatures atoms 

 readily emit electrons, and hence reactions occurring at these 



1 The writer has just learnt that Bohr, continuing some work begun 

 by Born and Landre, has applied liis own method with some success to the 

 dynamics of the Lewis-Langmuir model, and published a paper in one of 

 the German scientific journals. At the moment the paper has not come to 

 hand, but the writer hopes to refer to it in the next issue of Science Pro- 

 gress. 



