OF EXPANSION OF SUPEEHEATED STEAM. 
597 
Summary of Results. 
The law of expansion of gaseous bodies is expressed by the formula 
E + ^ PV 
E + ^,“P,V,’ 
E= 
PV^i-PiV,^ 
PiVj-PV 
? 
where E is a constant. The values of E thus deduced have been placed in the last column 
of the foregoing Tables. They show a decreasing rate of expansion from the saturation- 
point upwards until (at a certain increase of temperature) the rate of expansion coincides 
with that of a perfect gas. 
Taking from the preceding Tables the two results, which in each case represent the 
rate of expansion at the greatest distance from the saturation-point, we have the 
following values of E : — 
(1) 474-48 
450- 11 
(2) 455-57 
443-86 
(3) 466-85 
451- 94 
(4) 464-83 
460-79 
(5) 460-28 
9)4128-71 
Mean value of E= 458-74 
The value of E for air, as ascertained by Regnault, is 459. That assumed for a perfect 
gas by Rankine is 461-2. 
Hence the conclusion which we suggested in our previous paper has been satisfactorily 
demonstrated in more carefully conducted experiments, and the rate of expansion of 
superheated steam is shown to be almost identical with that of air and other permanent 
gases, if calculated at temperatures not too close to the maximum temperature of 
saturation. 
