1903.] Measurement of the Pressure Coefficient of Oxygen. 



Final Results. 



383 



Five series of observations were taken, which are indicated in the 

 first column of the table by Roman figures. The pressure of the gas, 

 when the bulb was in ice, is tabulated in the second column. In the 

 third and fifth columns the number of individual observations are 



p -P. 



recorded. The final corrected values of Pn and 



are inserted 



in the fourth and sixth columns respectively. 



After Series I had been taken, about half of the oxygen contained 

 in the bulb was allowed to escape, and the second series obtained. The 

 thermometer bulb was then completely evacuated and refilled with 

 fresh oxygen, which was used in Series III and IV. The thermometer 

 was again evacuated and refilled with fresh oxygen, with a view to 

 taking another set of observations; but owing to an unfortunate 

 accident to the apparatus, the work was interrupted after the two 

 observations recorded in Series V had been obtained. 



On plotting the values of the coefficient against the initial pressures, 

 the value at zero initial pressure is found on linear extrapolation to 

 lie between 0-003664 and 0-003665, a value which is higher than that 

 similarly obtained for nitrogen from Chappuis's determinations, and 

 likewise higher than the pressure coefficient of hydrogen, 0'0036625, 

 obtained by Travers and Jaquerod. The difference, although possibly 

 within the limits of experimental error, might be explained on some 

 such assumption as the association of the gas molecule at lower 

 temperatures. 



Calculation of the Tliermodynamical Correction at Zero Temperature from 

 the Pressure Coefficient and known Data. 



It is of interest to deduce the scale correction at C for oxygen, 

 using the method suggested by Callendar,* and the coefficient 

 calculated above. The notation adopted is as follows : 

 * 'Phil. Mag.,' vol. 25, 1903, p. 48. 



