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



and from the views which I have in reservation, it appears that 

 the same irregularity of figure Will be one cause of condensation 

 when the compression is sufficient to induce a certain degree of 

 density. Hence, therefore,' the density being the same, the 

 compression will be the greater the greater the temperature ; 

 and, therefore, at a greater temperature a greater compression 

 will be needful to produce condensation. But if a greater tem- 

 perature in the vapour require a greater compression to convert 

 it into a fluid, so, conversely, a greater temperature in the fluid 

 will require a greater compression to prevent its being converted 

 into vapour ; and, consequently, the greater the compression, the 

 greater will be the temperature requisite to produce ebullition. 



This conclusion will be true for all fluids whose vaporisation is 

 attended with a division in the particles ; and, therefore, for all 

 fluids with which we are at present acquainted ; but it seems 

 possible to devise cases in which it would not, perhaps, hold 

 o-ood. However, as such cases have not yet occurred, and pro- 

 bably never will occur, in nature, it would be useless to detail 

 them. We may hence consider it a general law that the tem- 

 perature of ebullition of all fluids is increased with an increase, 

 and diminished with a diminution of compression ; and, conse- 

 quently, that at all seasons the temperature of ebullition of any 

 jiuid will be the same, the external pressure being the same. 



From the view 1 have taken of ebullition, it follows, that the 

 increments of the squares of the true temperatures of ebullition 

 are proportional to the increments of the compressions ; and, 

 therefore, the increments of the Fahrenheit temperatures of 

 ebullition are also proportional to the increments of the com- 

 pressions. Consequently this being the case with every fluid, 

 it would follow that the same excess or defect of compression 

 will in all fluids produce the same excess or defect in the Fah- 

 renheit temperatures of ebullition ; and, therefore, the Fahren- 

 heit temperatures of ebullition of all fluids, when the fluids are 

 removed from the ordinary pressure of the atmosphere to a 

 vacuum, will be lowered the same number of degrees, which 

 agrees with the experiments of Prof. Robinson. These infer- 

 ences, as I have already mentioned, are drawn from a general 

 view of the principal cause of ebullition, and do not, therefore, 

 include the minor circumstances ; and hence cannot be expected 

 to agree mathematically with phenomena. . From the views 

 indeed to which I have alluded, I find that the Fahrenheit tem- 

 perature of ebullition ought to increase and decrease more 

 rapidly than the compression^ a circumstance which is in unison 

 with the experiments of De Luc, Betancourt, and Shuckburgh. 



Philosophers have long observed that different fluids boil at 

 different temperatures. This phenomenon evidently depends on 

 the different magnitudes of the particles and the different degrees 

 of the adaptation of their parts. Other things being alike, the 

 temperature of ebullition will be the greater the greater the par- 



