294 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



TABLE V — continued. 



computation is simpler for two reasons. In the first place, /u. and 

 dfx/dt are both so small that the temperature can be assumed constant 

 along a curve of constant H. d/x/dt is then constant in the integra- 

 tion. And in the second place d^/dt can be computed from Bucking- 

 ham's 42 equation for fx against t', both in reduced units, namely, 



,_ 0.209 

 ^ ~ t' - 0.32 



0.0368. 



This is corrected for the fact that although, in his paper, 100 inches of 

 mercury is taken as the unit of pressure, his critical pressures are ex- 

 pressed in atmospheres. It was shown in the preceding paper that 

 this equation can safely be assumed to hold for steam at very high 

 superheats, since it is known to hold for the other gases which Buck- 

 ingham discusses, and they are known to be connected with steam by 

 a law of corresponding states. 



This simpler process has been carried through for the four very high 

 temperatures mentioned in the last part of Table V, with the results 

 there presented. These results are the basis of the high superheat 

 part of the Steam Tables of Marks and Davis. 



42 Bui. Bureau of Standards, 1907, 3, 263. 



