164 THOMSON ON CARNOT'S 



and we deduce the following very remarkable con- 

 clusions : 



(1) For the saturated vapors of all different 

 liquids, at the same temperature, the value of 



(1 a) -~- must be the same. 



(2) For any different gaseous masses, at the 



same temperature, the value of , . f- must be 



vdq/dv 



the same. 



(3) The values of these expressions for saturated 

 vapors and for gases, at the same temperature, 

 must be the same. 



31. No conclusion can be drawn a priori re- 

 garding the values of this coefficient JJL for different 

 temperatures, which can only be determined, or 

 compared, by experiment. The results of a great 

 variety of experiments, in different branches of 

 physical science (Pneumatics and Acoustics), cited 

 by Carnot and by Clapeyron, indicate that the 

 values of JJL for low temperatures exceed the values 

 for higher temperatures ; a result amply verified 

 by the continuous series of experiments performed 

 by Regnault on the saturated vapor of water for all 

 temperatures from to 230, which, as we shall 

 see later, give values for /* gradually diminishing 

 from the inferior limit to the superior limit of 



