240 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 



studying chemical equilibria. The application of the quantum 

 theory to band spectra promises to be of the utmost importance in 

 chemistry. By enabling us to determine the moments of inertia 

 of chemical molecules, the actual distances between the nuclei of the 

 atoms in molecules can be found. Apparently our most accurate 

 determinations of the heats of dissociation of elementary gases can 

 be obtained from the band spectra through a knowledge of the 

 energy levels of the various possible states of the molecules. In 

 recent numbers of the Journal of the American Chemical Society, 

 particularly in the paper of Giauque and Johnston, we see the be- 

 ginnings of what promises to be the most accurate and fertile source 

 of knowledge of chemical equilibria. From a detailed knowledge of 

 the spectrum, for example, of oxygen, and without recourse to any 

 other experimental determinations, the specific heat at all tempera- 

 tures can be calculated, and the entropy of oxygen at all tempera- 

 tures is thus found. This, together with the heats of reactions, 

 which may be found by a similar method, makes possible the calcula- 

 tion of the degree of dissociation of oxygen and will ultimately make 

 possible the calculation of all chemical equilibria. 



The remarkable work of Dennison, Bonhoeffer, and Eucken in pre- 

 dicting and isolating parahydrogen should prove to the chemist how 

 many of his chemical discoveries will be obtained in the future by the 

 application of these new theories of physics. 



Gurney and Condon have recently derived from the wave 

 mechanics an explanation of the fundamental law of radioactivity. 

 Similar methods will probably before long enable us to understand 

 the processes involved in chemical reactions far better than we ever 

 have before. 



Physics and chemistry are being inevitably drawn closer together. 

 It seems that there has never been a time when we can predict with 

 such certainty rapid progress in fundamental chemistry, for the new 

 theories of physics have as yet scarcely begun to be applied in the 

 field of chemistry. The physicist on the other hand has much to 

 learn from an increased knowledge of chemical phenomena which 

 should provide him with a richness of experimental data far greater 

 than any he has yet had an opportunity to use. 



Unfortunately, although theoretical physics and chemistry are 

 thus supplementing each other and in many respects are being 

 merged into a new science, there are remarkably few men as yet that 

 have received adequate training in both sciences. Before long, I 

 hope, sharp distinctions between physics and chemistry will no 

 longer exist, but at present there seems to be a very practical 

 distinction. 



