6 Grindlev, TJicrviodynaviics of Superheated Steam. 



entropy determined from the author's experiments, the 

 density being given by Ramsey and Young's results, and 

 that for the saturated condition by Regnault's results 

 solely. 



The calculations already made shew that, from i to 5 

 atmospheres pressure and between temperatures 2io°F. 

 and 330^F., which is as far as the}- have been carried, the 

 mean value of the index Jt was 1-286, a value not far 

 removed from the theoretical ratio of the specific heats in 

 a gas composed of triatomic molecules. 



IV. On the value of the product CKp. 

 In the remarks on the specific heat Kp, it was stated 

 that the values of Kp thus deduced from Regnault's results 

 did not vary with the pressure, and from this circumstance 

 the author was led to make further calculations on the 

 values of the product CKp, where C is the cooling effect, 



— , produced, by free expansion, in superheated steam. 



dp 



Thus it was found* that a particular relation existed 



between the variations oi Kp. C, and (-j:)^ namely 



4(A-.)=-rp)=-i(CA',) ... (3) 



Cp^ ' \CT-j CT 



and, assuming Regnault's law, the first and last of these 

 three expressions was found to be zero. 



For independent evidence as to the value of —^ 

 the author examined the results of Ramsey and 

 Young's experiments on the densities of superheated 

 steam. The results have been rather surprising, as 

 Messrs. Ramsey and Young had already announced as 

 one of the results of their researches that f4^j vanishes. 

 Carl Barusf, however, found that this relation did not 



* P/u7. Trans., 1900, \'ol. 194, p. 31. 

 t P/it7. Mag., Vol. 30, 1890, p. 358. 



