CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL 

 LABORATORY, HARVARD UNIVERSITY. 



NOTES ON CERTAIN THERMAL PROPERTIES OF STEAM. 



By Harvey N. Davis. 

 Presented by John Trowbridge, December 8, 1909; Received December 30, 1909. 



§ 1. Introduction 267 



§ 2. On the Cp values available for the present purpose 269 



§ 3. On the total heat of saturated steam 



A. The determination of H — H 100 272 



B. The value of H 100 280 



C. Extrapolation formulae for H and L 281 



§ 4. Discussion of the specific heat of superheated steam, including 



A recomputation of Regnault's values 285 



Computations based on the Joule-Thomson effect 289 



Computations with Planck's equation 295 



§5. Clausius' " Specific heat of saturated steam " 303 



§ 6. The critical volume of water 305 



Summary of the results in this paper 310 



1. Introduction. 



It is the purpose of this paper to collect and correlate certain 

 material on the thermal properties of steam. A part of this material 

 was published in a technical journal a year ago. 1 Other parts of it 

 have been contributed as discussion of papers by others in that journal 

 and elsewhere. Still other parts of it have been used in a recent book. 2 

 The rest appears here for the first time. It all centers around a new 

 determination of the total heat of saturated steam. 



The previous determinations of the total heat of steam (H), and of 

 the closely related latent heat of evaporation (L), will first be summa- 

 rized. The most famous of them was published by Regnault in 1847. 

 His experiments were so numerous, covered such a wide temperature 

 range, and were characterized by such perfection of detail as to be 

 accepted as the foundation of the engineering practise of the world, 



1 Jour. Am. Soc. of Mech. Engs., 1908, 30, 1419. 



2 Marks and Davis, Steam Tables and Diagrams. 



