118 M, R. Clausius on the Moving Force of Heat, 

 pennanent gases. This equation was 

 c/rsc + AR; 



and when for c the equivalent expression j is introduced, we have 



For atmospheric air, the number 0*267, as given by De Laroche 

 and Berard, is generally assumed for ^ ; and for k, as given by 



Duloner, 1-421. For the determination of R= -^r^, we know 



that the pressure of one atmosphere (760 millims.) on a square 

 metre amounts to 10333 kils. ; and the volume of 1 kil. atmo- 

 spheric air under the said pressure and at the temperature of the 

 freezing-point is =0*7733 cubic metres. From this follows 



and hence 



R=128§|^ =39-36, 



1_ __ 1*421x29*26 __ 

 A"" 0-421x0*267 -^^"^ 



that is to say, by the expenditure of one unit of heat (the quan- 

 tity which raises 1 kil. of water from 0° to 1°) a weight of 370 

 kils. can be raised to a height of 1 metre. This value, however, 

 on account of the uncertainty of the numbers 0*267 and 1*421, 

 is deserving of little confidence. Holtzmann gives as the limits 

 between which he is in doubt the numbers 343 and 429. 



The equation (Va.) developed for vapours can be made use of 

 for the same purpose. If we apply it to the vapour of water, 

 the foregoing determinations, whose result is expressed in equa- 

 tion (26.), may be used. If, for example, the temperature 100° 

 be chosen, and for p the corresponding pressure of one atmo- 

 sphere = 10333 kils. be substituted in the above equation, we 

 obtain 



i-=257.(.-<7). .... (35.) 



If it now be assumed with Gay-Lussac that the specific weight 

 of the water-vapour is 0-6235, we obtain s= 1*699, and hence 



A 



Similar results are obtained from the values of C contained in 

 Table I., which Clapeyron and Thomson have calculated from 

 equation (V.). K these be regarded as the values of A (a -fO 



