748 Mr. J. G. Stewart on the Inapplicability of 



magnetism by increasing the percentage of tungsten. When 

 the research is carried further, and the effects of quenching 

 at different temperatures are observed, it will be of interest 

 to note at what point an increased percentage of tungsten 

 gives either a stronger or a more permanent magnet. 



The work described above was carried out in the Natural 

 Philosophy Institute of Glasgow University, and my thanks 

 are due to Professor Gray and to Dr. J. G. Gray for the 

 interest they have taken in the progress of the research, and 

 for valuable advice and suggestions. 



LXXVIII. The Inapplicability of Boltzmann s Equipartition 

 Hypothesis to Gases in a State of Change of Internal 

 Energy; and its bearing on the experimental determination 

 of the Specific Heat of Gases. By J. G. Stewart, M.Sc, 

 of Birmingham University* . 



Part I. 



Unequal Partition of Energy in Gases in a State of 

 Change of Internal Energy. 



BOLTZMANN'S equipartition hypothesis, with the re- 

 striction usually stated regarding internal molecular 

 freedoms, appears to be generally accepted for gases under 

 all conditions except those of chemical change. I propose, 

 in this paper, to draw attention to the unequal partition 

 which certainly exists in particular cases which have come 

 under my attention ; and thereafter to consider the errors 

 which would result in certain experiments relating to the deter- 

 mination of the specific heats of gases at high temperatures. 



The possibility that in certain cases Boltzmann's hypo- 

 thesis might not be true first occurred to me in connexion 

 with the flow of gases through nozzles. In a paper just 

 published f I have given evidence from the behaviour of 

 gases in nozzles for the contention of unequal partition 

 of energy in a rapidly expanding gas. 



Boltzmann's hypothesis states the law of equilibrium for 

 a gas under static external conditions ; under dynamical 

 conditions, owing to the high molecular velocities it has always 

 been tacitly assumed that equilibrium is reached much more 

 rapidly than any change which could take place, i. e. that 

 Boltzmann's hypothesis is still true. 



The behaviour of gases will appear more clearly by the 



* Communicated by the Author. 



f " Theory of the Flow of Gases through Nozzles/' Journal of Inst, of 

 Mech. Engineers, October 1914. 



