yg ,.,;,.-. , H;I;\\I:N .IKNKIN AND MR D. R. PYE ON TJII-: 



Tli,- HI- <>(' tin- n.u^l, a-rniement among the observations is that the sain.- data 

 |*en n'1-.-.t.-.lly "s.-.l. Thus CAILLETET and MATHIAS' densities were used by 



MATHIAS | .^ work - ollt t j ie j r observations, 

 CHAPPUIS J 



CAILLKTKT . , ,. 



> in their calculations. 

 and MATHIABJ 



AMAUAT'R densities were used by 



KUENEN and ROBSON j ^ ^ calculations . 



MOLLIEB J 



REONAULT'S pressure-temperature curve was used by 



CAILLETET and MATHIAS "1 . . , , . 



> m their calculations. 

 MOLLIER (in part) J 



The difference between the various results and ours may be traced to the inaccuracy 

 of REGNAULT'S (and consequently MOLLIER'S) pressure-temperature curve and to the 

 error in CAILLETET and MATHIAS' gas densities below 20 C, and to the uncertainty 

 of the extrapolated values of the densities used by MOLLIEB and KUENEN and 

 ROBSON. 



All the calculated values of L were obtained by means of CLAPEYRON'S equation 



where 



V = specific volume of saturated vapour, 



v = liquid at saturation temperature. 



Their accuracy therefore depends on the accuracy of the two factors dp/dd and 



(v- v ). 



The differences in the pressure-temperature curves and their gradients have already 

 been discussed, so that it is only necessary to consider now the other factor (Vv). 

 The specific volume of the liquid v is much smaller than of the vapour, and the values 

 obtained by different observers do not differ much ; it is, therefore, not necessary to 

 discuss it here. The specific volume of the saturated vapour, V, is much more 

 doubtful. In fig. 19 are plotted 



(1) AMAUAT's(5) smooth curve from his observations of V. 



(2) CAILLETET and MATHIAS' (ll) smooth curve from their observations of V. 



(3) KUENEN and RoBSON's(9) extrapolation (by the Law of Corresponding states) 

 of AMAOAT'S curve. 



(4) MOLLIER'S (1) extrapolation of AMAGAT'S curve. 



(5) Our values, calculated from our observed values of L by CLAPEYRON'S equation, 

 using BERN'S (6) liquid densities. 



Values taken from our smooth curve are given in Table IX. 



