﻿322 Mr. Baly and Dr. Ramsay on the Relations of Pressure, 



When gauge F was hot the reading of gauge E was 

 379-71. 



Therefore the reading of gauge F was 

 379-71 x 1-05 = 396-80. 



Boiling-point of aniline at barometric pressure 764 - 9 millim. 

 = 184°-66 C. 



Therefore 396*80 : 247*782 : : # + 184-66 : # + 125 ; 



.-. #=273-741. 



.-. Coefficient of expansion = 273 ? 741 - 



Vacuum = 3'47 millim. 



In making these experiments the readings were taken at 

 the same reading-points throughout the whole operation so 

 as to ensure accuracy. It will be evident that the volumes 

 represented by the divisions on the gauge do not influence 

 the result, and provided that the whole calculation is made 

 from readings at the same points, the volumes at these points 

 may be given any value whatever. The accuracy of the 

 experiment therefore does not depend in any way on the 

 accuracy of the volumes at the reading-points, but only of the 

 pressures, which were very carefully read to within 01 

 millim. 



The following coefficients of expansion of hydrogen were 

 obtained : — 



(T = temperature of jacket ; £ = temperature of reading.) 



Pressure. 





T. 



t. 



4*7 millim. 



i 



273-5 



184-66 C. 



_ 12°5 C. 



3-47 „ 



1 

 273 74 



184-33 



138 



•25 „ 



1 

 276 



132-32 



147 



•096 „ 



1 



297 



132-27 



17-3 



•077 „ 



1 



132-33 



16-3 



The purity of the hydrogen in these experiments was 

 satisfactorily proved by both the constancy of the gauge- 

 readings in each experiment and by the factor of exhaustion 

 being equal to theory. 



If the above results be plotted on a curve it shows that 

 hydrogen expands quite normally till a pressure of '4 millim. 

 is reached, when its elasticity increases with further decrease 

 of pressure. Many other experiments were made, with similar 

 results. 



