Law of Molecular Force. 173 



Volumes of 1 kilogramme of Liquid C0 2 , in litres. 





18°. 



0°. 



-23 







Amagat. 



Equation. 



Cailletet 



and 



Hautefeuille. 



Equation. 



Cailletet 



and 



Hautefeuille. 



Equation. 



100 atmosph. 

 200 „ 

 300 „ 



1-169 

 1065 

 1-025 



1-266 

 1-142 

 1-064 



1-016 

 0-962 

 0-931 



1-153 

 1-071 

 1-016 



0-916 



0-888 

 0-869 



1-064 

 1-010 

 0-971 



It will be observed that the volumes given by the equation 

 are all larger than those given by experiment. But at the 

 lower pressures the disagreement is such as we are not 

 unprepared to meet if we admit that capillary action alters 

 the critical temperature from 42°*8 to 31°, and also produces 

 the discrepancies between Amagat's and Andrews's deter- 

 minations for 35°'5 ; for from the numbers tabulated before 

 for 35°* 5 we see that the deformation of the isothermals due 

 to capillary action is greatest for pressures about 100 atmo- 

 spheres, and we cannot expect the deformations to disappear 

 in a sudden manner as we pass from 35°*5 to 18°. At the 

 higher pressures the numbers given by the equation for 18° 

 approach towards equality with those of Amagat; but the 

 differences between the equation numbers and Cailletet and 

 Hautefeuille's for the same temperature still amount to about 

 10 per cent, even at the high pressures. But the determina- 

 tions of these experimenters and those of Amagat are not 

 reconcilable with one another, as can be seen by forming the 

 products pv and converting to Amagat's units, and plotting 

 the results on Amagat's diagrams representing all his own 

 experimental results (Ann. de Chim. et de Pkys. 5 ser. xxii.); 

 and in a less striking manner we can see the discrepancies by 

 noting that the expansion between 0° and 18° as reckoned 

 from Amagat's and Cailletet and Hautefeuille's results is 

 much greater than that reckoned from —23° to 0°, although 

 the latter interval is nearly 1*3 times the former. The 

 following table shows this conflict in the experimental 

 results : — 



