



I'ki i \( ! 



A TABLE of the thermal properties of a vapor should possess two 

 chanu ten-lies, consistency and accuracy. A table is thermodynami- 

 cally consistent \\ h n tin tabular \.ilues are obtained from equations 

 that are properly connected by the necessary thermodynamic relations, 

 Mich as the ('lausius and Clapeyron relation*,; it may be considered 

 rate if the calculated values show satisfactory agreement with 



hy experimental data. 



1 he older tables of the properties of steam were neither consist 

 nor acctn The tabular \ahn- were calculated from empirical formu- 



las based chiefly on Regnault's d. 1 tin n'- < 



was not recognized. Two sets of tables have been based on the general 

 theory developed by Callendar. These are absolutely consistent, but 

 in the light of the knowledge acquired from the Munich experiments, 

 they can no longer be regarded as accurate. In certain tables that ha\e 

 appeared recently have been embodied the results of the Munich experi- 

 ments and al>o the researches of Dr. Davi> on the total heat of steam. 

 ' tables are undoubtedly far more accurate than the earlier tables, 

 but, having a more or less empirical basis, they are not rigorously con- 



nt. 



The tables of the properties of saturated and superheated steam here 

 presented are based on a new formulation the eential features of which 

 liscussed in the first section of the book. A more complete exposi- 

 tion will be found in Bulletin No. 75, Engineering Experiment Station, 

 UnivciMt\ of Illinois. The new theory correlates perfectly the experi- 

 ments on the volume and specific heat of superheated steam; it gives 

 values of the heat content of saturated steam that agree with those 

 deduced by I>avi- from the throttling experiments; and, in general, it 

 meets satisfactorily all the te>t> furni>hed by the available experimental 

 e\ idence. The tables derived from the formulation are necessarily cou- 

 nt, and they are at the same time extremely accura 

 The tables of the properties of ammonia are based on a formulation 

 worked out by Mr. YV. K. Mosher and the author. (Bulletin No. 66, 

 Eng'g Expci MI. I'niv. of 111.) Since, in the case of ammonia, 



the experimental evidence is far from complete, the formulation is re- 

 garded as only tentati\c. and the tables will perhaps require 

 further experiments are made. 



