ON THE MECHANICAL EQUIVALENT OF HEAT 413 



Estimating the weight rather arbitrarily, I have combined them as 

 follows : 



No. 



1 

 2 

 3 



4 

 5 

 6 

 7 

 8 

 9 

 10 



Mean 331-75 



Or, corrected for the normal carbonic acid in the atmosphere, it be- 

 comes 331-78 metres per second in dry pure air at C. 



From Eegnault's experiments on the velocity in pipes I find by 

 graphical means 331-4 m. in free air, which is very similar to the above. 



Calculation from Properties of Gases 



K= specific heat of gas at constant pressure. 

 lc = specific heat of gas at constant volume. 

 p = pressure in absolute units of a unit of mass. 

 v = volume in absolute units of a unit of mass. 

 H = absolute temperature. 

 J= Joule's equivalent in absolute measure. 

 = K 



General formula for all bodies: 



_ 1 



~~ l _j^_(dp_\ (dv_\ ' 



V 1 I dv \ 



r = -7-i-r-i 



T _ /* ( dp \ / dv \ f 

 *' 7? \7fc).\dJ ) F^T' 



