106 Mr. E. F. J. Love on the 



was placed on a strip of platinum, and the strip placed on 

 the bottom of the iron box. The same increased leak was 

 observed when heat was applied in this case. 



With uranium nitrate the same series of experiments gave 

 no increased leak in any case. 



March 1899. 



V. The Joule- Thomson Thermal Effect ; its Connexion with 

 the Characteristic Equation, and some of its Thermodynamical 

 Consequences. By E. F. J. Love, M.A., F.R.A.S., As- 

 sistant Lecturer and Demonstrator of Natural Philosophy 

 in the University of Melbourne'*. 



(1) Introductory. 



THE results obtained by Lord Kelvin and the late Dr. Joule 

 in their famous investigation into the "Thermal Effects 

 of Fluids in Motion " have hitherto been utilized almost exclu- 

 sively for one special purpose, viz. for determining the relation 

 between various gas-thermometer scales and the absolute scale 

 of temperature. But this is not the only information that can 

 be obtained from them ; and the present paper has been 

 written partly in order to deduce some of their further 

 consequences. 



This deduction ? however, is not the writer's sole object. He 

 desires to indicate the relation which must exist between the 

 formula assigned to the Joule-Thomson effect, considered as a 

 function of the temperature, and the particular form adopted 

 for the characteristic equation of a gas ; in this way it is 

 possible to supply some sort of theoretical basis to the various 

 formulas put forward by different investigators, and to obtain 

 some idea as to which of them is the most likely to be 

 correct. With a view to an orderly development of the 

 subject this discussion will be taken first ; it will be followed 

 by a deduction, from Joule and Lord Kelvin's results, of 

 the relation between the intrinsic energy of a gas and its 

 volume, upon which is based a new method of calculating 

 the ratio of the two principal specific heats of a gas. A 

 concluding paragraph deals with some points in the thermo- 

 dynamics of substances at their temperature of maximum 

 density. 



* Communicated by the Physical Society ■ read February 24, 1899. 



