270 Mr. Herapath on True Temperature, and the [Oct. 



Temp. 

 Fahr. 



212° 

 250-3 

 293-4 

 343-6 



Elasticities in 

 inches, of 

 mercury by 

 Southern. 



30° 

 60 

 120 

 240 



h S th 31 " ^P" 8 r- 0I " steatn Differences 



and Sharpe. 



by new theory, 



0-4545 

 0-9090 

 1-8180 

 3-6360 



0-4545 

 0-8591 

 1-6184 

 3-0315 



results. 



of|Ratios of 

 results. 



0-0000 

 0-0499 

 0-1996 

 0-6045 



i 



6 6 

 (i 9 8'J 



6 6 

 7 4 14 



6 6 

 7 9 1 '6 



From this table it is plain, how very trifling an error it would 

 require to make any of Messrs. Sharpe and Southern's experi- 

 ments coincide with the theory I have advanced. Even in the 

 last case, an error of less than one-sixth only, which on this 

 subject is considerably within the probable errors of observation, 

 would be sufficient to make the two numbers coincide. How 

 desirable, therefore, would a careful repetition of such experi- 

 ments be? But to give the finishing stroke to the theory of 

 vapours, there is wanting a correct and extensive set of experi- 

 ments on the temperatures of the boiling points of different 

 fluids under various compressions. Such experiments as these 

 carefully made for a great range of temperature, and connected 

 with the expansions of the fluids under similar circumstances, 

 would be of more service towards perfecting the laws of cohe- 

 sion, the theory of the steam engine, and, it appears to me, even 

 the laws of the reflection and refraction of light, than almost all 

 the experiments that have yet been made valuable as they are. 

 De Luc, Betancourt, Shuckburgh, and, more lately, Gay-Lus- 

 sac, have set philosophers some fine examples in this interesting 

 and useful part of experimental physics ; but still their experi- 

 ments have not that extent which would enable the analyst to 

 investigate the true laws that connect the temperature of ebulli- 

 tion with compression ; and unhappily the little discordancies 

 found in their results are more calculated to display the difficulty 

 of the inquiry, than to render the experiments useful to the philo- 

 sopher. 



To this same irregularity of figure in the vaporous particles 

 another remarkable property of vapours seems to be attributable. 

 u It is well known," says Dr. Thomson, p. 74, of vol. i. of his 

 System of Chemistry, Sixth Edition, " that the condensation of 

 vapours is greatly assisted by pressure ; but the effect of pres- 

 sure diminishes as the temperature of vapours increases." Now 

 from the views to which I have alluded, and which probably at 

 some future period I may unfold, it appears that if the vapours be 

 condensed to a certain degree, the irregularity of the corpuscular 

 figures, and their adaptation, or a considerable deviation from 

 sphericity, will very much contribute to unite the particles and 

 produce condensation ; but the more violent the collisions, or 



