106 Mr. C. T. Blanshard on the Role of Atomic Heat 



gas will not emit its definite radiations however high the 

 temperature to which it is raised, unless there is chemical 

 decomposition of the molecules going on. It' that be so, the 

 pettier does not act as an equalizer of the kinetic energy 

 between the different modes of vibration of the molecules, 

 and the ordinary theory of gases need make no reference to 

 the aether. 



If I have understood aright, a similar view has been ex- 

 pressed as at any rate a possible explanation of the difficulty 

 as to the application of Maxwell's distribution theorem in the 

 theory of gases, by Prof. Boltzmann himself. The law of 

 distribution of energy is perhaps unassailable for the case of 

 molecules like small spheres, with three degrees of freedom, 

 all translational. By including the rotational modes of free- 

 dom, which may be none at all for a monad gas, only two 

 for a diad, and three for other types, and these possibly not 

 complete, a sufficient number of freedoms is obtained to cover 

 the known range of values of the ratio of the specific heats. 

 The introduction of any vibrational types would make too 

 many ; so on this ground also it is not likely that such types 

 can enter into those among which the thermal energy is 

 divided. — December 4.] 



YI. The Role of Atomic Heat in the Periodic Series of the 

 Elements. By C. T. Blanshard, M.A* 



BY a study of the latest, or most accurate data of atomic 

 heats and melting-points I have been enabled to 

 arrive at definite relationships between them, which I will 

 endeavour to set forth. In Grundzilge der theoretischen 

 Chemie, Leipzig, 1893, p. 106, Lothar Meyer says : — " The 

 periods of fusibility do not coincide with those of other 

 physical characters, are also less regular than these, but are 

 in close relationship to the atomic volume." With regard to 

 Dulong and Petit 1 s law, W. Oitwald says (' Outlines of 

 General Chemistry/ English translation, p. 177) : — " We can 

 only note empirically that the law holds good for substances 

 with atomic weights higher than thirty." 



A survey of the accompanying curve of atomic heats, made 

 to correspond with Lothar Meyer's curve of atomic volumes, 

 will, notwithstanding several blanks and several doubtful 

 values, demonstrate the two following laws of atomic heat : — 



1. The atomic heat decreases in any series from the monad 

 to the tetrad element, and then increases till a maximum is 

 reached with the heptad element. 



* Communicated by the Author. 



