Manchester Memoirs, Vol. xIzk (igoi) No. ^. 



III. The Thermodynamical Properties of Superheated 

 Steam, and the Dryness of Saturated Steam. 



By J. H. Grindley, M.Sc. 



Received January Slh, igoi. Read December iith, igoo. 



I. TJie total heat of formation of SuperJieated Steam. 



In a previous paper* by the author on the subject of 

 superheated steam, a description is given of some 

 experiments on the coohng effects produced by the free 

 expansion of steam obtained by the evaporation of water 

 in an ordinary Lancashire or locomotive boiler. As 

 regards its dryness, the condition of the steam used in 

 the experiments was, as far as could be arranged, the 

 same as that on which Regnault made his experiments 

 on the latent and total heats of evaporation of saturated 

 steam, as it was intended to use his results in the deduction 

 of the properties of superheated steam. 



Since writing this paper, the author has been consider- 

 ing his experimental results, and, in the light of further 

 evidence by other experimenters, he has been led to 

 calculations the results of which may be of use and 

 interest. 



In the first place, the author's own experimental 

 results enable a table, of the total heats of formation of 

 superheated steam at various temperatures and pressures, 

 to be made, which will be of use. This table is compiled 

 by calculations of a nature described in the above paper, 

 and it contains values of the total heat of formation of 

 superheated steam from water at 32"F. in B.T.U.'s, for 

 every 5 lbs. pressure per square inch, and every 5°F., over 

 *Phil. Trans., Vol. 194(1900), pp. i — 36. 



March nth, igoi. 



