Manchester Memoirs, Vol. xli. (1896), No. 3. 7 



steam as determined by Regnault's experiments, by a 

 formula which is based on a misunderstanding of the 

 meaning of " the specific heat, at constant pressure, for 

 steam when in the gaseous state," as determined by 

 Regnault. And that this must have been the case with 

 the other results would seem to follow from the fact that 

 this formula, when based on the correct meaning, affords 

 no definite result at all under the circumstances of the 

 experiments. 



It has thus seemed to me important not only to call 

 attention to the error in reduction by which certain of 

 these results have been obtained, but also to indicate, and 

 if possible to verify, a method by which experiments 

 could be made, so that Regnault's determination of the 

 specific heat of steam gas could be correctly used to 

 ascertain whether or not such latent water does exist in 

 drained steam — that is, to ascertain whether Regnault's 

 experiments on the specific heat of steam gas are consis- 

 tent with his experiments on the latent heat of steam. 



In the present paper the purpose is limited to pointing 

 out the theory of the reductions, and to giving indications 

 of the method of experimenting, the general character 

 of the apparatus, and the precautions necessary. 



The Theory of the Reductions. 



By the law of conservation of energy, when a steady 

 stream of matter flows through a chamber with fixed walls, 

 so that the condition within the chamber is steady, the 

 energy of the matter which enters (potential and actual) 

 is equal to the energy which leaves in the same time, 

 and hence is equal to the energy of the matter which 

 leaves, together with such energy as may escape into the 

 walls of the chamber. Thus, if a stream of fluid flows 

 in a horizontal direction through a fixed passage and if 



