58 MOLECULAR AND ATOMIC ENERGY 137 



molecules consist of two atoms there are several which do 

 not obey the laws of Boyle and Avogadro with exact- 

 ness; for these, then, Clausius' law cannot be exactly 

 true. To this class of gases belongs, for instance, chlorine 

 and many gaseous chlorine compounds. 



Possibly we may also refer to this behaviour of chlorine 

 the striking circumstance that, of the possibly eight sub- 

 stances for which the ratio of the atomic energy e to the 

 molecular energy E was found greater than 1, seven are 

 chlorine compounds. For these substances the temperature 

 at which the ratio of the specific heats C and c has been 

 determined will perhaps not have been high enough for a 

 complete breaking up of the vapour into single molecules 

 to have been attained. 



The deviation exhibited by ethyl ether will be explainable 

 in the same way. If the measurements had been made at 

 higher temperatures, there would doubtless have been found 

 a greater value of the ratio of C to c, as in the case of methyl 

 ether ; and the calculation would then have given a smaller 

 value ^ for the ratio borne by the atomic energy e to the 

 molecular energy E. 



The law that in real gases the share of energy possessed "") 

 by each atom of a molecule is always less than the trans- < 

 latory kinetic energy of the molecule would not therefore \ 

 be confuted by the eight exceptions. 



59. Dependence of the Specific Heat on the 

 Number of Atoms 



From the foregoing remarks on the nature of atomic 

 energy it at once follows that the total amount of atomic 

 energy ( depends on the number of atoms contained in the 

 molecule, and, indeed, must increase with this number. 

 That such is the case is at once seen by a glance at the values 

 of the ratio ( to E in the sixth column of the table in 55. 



On closer examination further regularities come to view. 

 Among them the fact is especially striking that the ratios 

 for the gases O 2 , N 2 , H 2 , CO, NO that head the table are 

 very nearly identical ; for them the whole atomic energy (5 is 



