302 PROCEEDINGS OF THE AMERICAN ACADEMY. 



end of his memoir (" Table M "), in which are given certain graphically 

 determined values of the coefficients in the formula 



p = b t + a, 

 which he, like Knoblauch, Linde, and Klebe, uses to represent his 

 isochors. The coefficient b in this formula is the same as the {dp/dt) v 

 in the main table of Knoblauch's paper, and can be used in the same 

 way. The values of C p computed from Battelli's table M with con- 

 densation effects eliminated, run even lower than Knoblauch's satura- 

 tion curve throughout the range of Figure 14. This indicates that 

 Battelli rather more than eliminated the condensation errors in his 

 discussion of his data. 



The contrast between the values obtained from Ramsay and Young's 

 work, where the wet steam error is known to exist, and those obtained 

 from Battelli's work, where it is known to have been consciously 

 eliminated, is so much like the contrast between Thomas' saturation 

 curve and Knoblauch's as to be a striking verification of the conclusion 

 reached on page 272. 



It is not probable that either of the three sets of volume measure- 

 ments are reliable enough to make the results computed in this section 

 worthy of much consideration as new determinations of C p . Their 

 value is chiefly as corroborative evidence on one side or the other of 

 the various doubtful points that have been mentioned. 



Be. Other indirect computations. — ) _ T „ ,. ... 



n D , ,. \ None ot the papers which 



(J. Resumes and discussions. — ) * r 



might be listed under Be or C are such as to be improvable by the use 

 of the new material in this and in the preceding paper, or to be of im- 

 portance in the present connection. They will not be discussed in 

 detail. 



Summary of this C p discussion : — 



1. Knoblauch's curves in general, and his saturation curve in 

 particular, are much nearer the truth than Thomas'. The evidence for 

 this is to be found on pages 287 and 298 to 302. 



2. Knoblauch's saturation curve runs somewhat too low at low 

 temperatures (see pages 290, 293 and 300). 



3. The low temperature end of Knoblauch's 1 kg. curve should be 

 somewhat raised, not only because of conclusion 2 above, but also so 

 as to agree better with Regnault's recomputed results (see page 286). 



4. Knoblauch's 1 kg. curve should be relocated at high superheats 

 so as to agree with that of Holborn and Henning. 



5. The spacing at high superheats of the curves corresponding to 

 pressures higher than 1 kg. is best determined by a new method 

 involving the Joule-Thomson coefficient (see pages 290 to 294). 



