Theory of Gases to the Properties of Diatomic Gases. 397 



I may now^ quote from the paper my conclusions :* "It is interesting 

 to note that u> [here] plays the part of a control in refraction, and that 

 the form of the dispersion curve is really due to the distribution law 

 and not to radiation. The value of o>/2ir obtained must be about three 

 times the frequency for the Na lines and hence w corresponds to a 

 frequency far beyond the violet. I see no grave objection to this 

 result, as the same result would arise in any theory in which a single 

 term is supposed to represent the facts. The controlling period must 

 l>e less than the imposed period to explain ordinary dispersion in the 

 spectral range. 



" The high value of u> precludes the possibility of explaining spectral 

 lines by the molecules of this theory. I am inclined to think that 

 spectral lines are in some way connected with dissociation, but not 

 necessarily of simple molecules. 



" I return to a suggestion which I made earlier, that these are due 

 to multiple molecules. "\Ve cannot avoid the conclusion that there are 

 such in a gas. They need not, and indeed do not, have a permanent 

 existence. It is only necessary that there should be a small proportion 

 on average. The frequencies of these small planetary systems are 

 probably less than the frequency of the molecule par excellence. 

 Further it is probable that their frequency will not be greatly affected 

 by pressure, but the number would probably increase with pressure. 

 This would agree with Professor Sir Norman Lockyer's observations 

 that the period of the lines does not alter much with pressure, but the 

 intensity does increase considerably with increase of pressure." 



Earlier in the paper I point out the importance of multiple 

 molecules in connection with the theory of the ratio of specific heats. 

 " The ratio of specific heats for chlorine indicates more nearly six 

 degrees of freedom, and one must either suppose that there is a con- 

 siderable proportion of the set B present, or else a proportion of 

 multiple molecules. The first supposition could hardly be supported 

 quantitatively on electrical grounds ; while the second is more probable 

 in view of the comparative proximity of chlorine, under ordinary con- 

 ditions, to its critical state." 



Note. In the Thesis presented to the University of Gottingen, for 

 his doctorate, Herr Karl Baedecker has measured the effect of tem- 

 perature on the dielectric constant for several gases. The thesis was 

 published in pamphlet form in August, 1900, and in the ' Zeitschrift 

 Phys. Chem.,' vol. 36, pp. 305-335. The bearing of his results on the 

 formula above given is analysed in the following table, 6 being taken 

 as temperature centigrade plus 273 0< 3. 



* These views were first expressed in n Fellowship Dissertation presented to 

 Trinity College, Cambridge, in August, 1900. 



VOL. LXIX. 2 F 



