THK THERMAL PROPERTIES OF STEAM 



u 



ut tin- constant c IB taken a* thr liquid volume r*. the terra Acp 

 is Apv' t \vlii. h is the small difference between the heat content i" and 

 the total heat q". Hence, when applied at the saturation limit, equation 

 (D) gives i" and the same equation with thr term Acp omitted gives qf'. 

 At th- .itm.it i<>n limit formula (D) may be checked with the Davis 

 formula for heat content, which U surely valid within the range 212- 

 400 F. The comparison is shown graphically in Fig. 5. The points are 



FIG. 5. 



i. .;.!-. 



COMPARISON or i "-Outre no* EQ. (D) WITH 

 THBOTTUMG ExnuuMBMT*. 



Pourri Dioocso 



those determined by Davis from the throttling experiments of Grindley, 

 Griessmann, and Peake, and tlu-y are plotted from the data given in 

 Table i of Davis's paper.* The ordi nates represent the difference be- 

 tween the i at the given temperature / and the i at 212 degrees. The 

 curve therefore represents the equation 



f'-f'm -/W. 



where i" is calculated from the formula and i" m - "5" -74- The curve 

 does not fit the points quite as well as the Davis second-degree curve, 



Proc. Am. AcacL, Vol. 43. P- 



