64 



Drs. J. P. Knenen and W. W. Randall. [Nov. 28, 



The results of our observations are laid down in the table. In 

 three cases (3, 4, and 6) the reading was taken at C , as well as at 

 the boiling-point of water; this enabled us to calculate the coefficient 

 of expansion between these two points. The result is shown in the 

 fourth column. The higher temperatures determined with these 

 thermometers have been derived from the observed pressures by 

 using the coefficients thus measured. As the barometric pressures 

 differed, more or less, from the normal value, the boiling-points had 

 to be reduced to normal pressure, for which operation we made use of 

 "the differences in Ramsay and Young's well-known tables.* In 

 calculating the temperatures of air thermometer I, where the reading 

 at 0° had been omitted, and of argon thermometer II, where we did 

 not take the reading in steam, we used the coefficients found with air 

 thermometer II and argon thermometer I, respectively, in the first 

 •case basing our calculations on the reading in steam. With the 

 hydrogen thermometer, where the reading at 0° had not been taken, 

 we accepted O003663 as the coefficient of that gas, and based our 

 calculations of the temperatures again on the reading in steam. 



Since the readings of the mercury surfaces, with the gas thermo- 

 meter as well as the barometer, were taken on a millimeter scale, an 

 occasional mistake in the final pressure of Ol or 2 mm. is by no 

 means excluded. Uncertainties of that amount do not, however, 

 account for the differences between the results obtained with the 

 different thermometers. The readings of air thermometer I are, 

 perhaps, somewhat less to be relied upon than the others, because 

 • they had to be observed, as was stated above, by one of us in the 

 absence of the other. The boiling-point of bromnaphthalene, as 

 determined with the helium thermometer, is also very uncertain, 

 because the position, of the mercury was not at all stable, probably 

 on account of the difficulty of obtaining rapid and smooth boiling of 

 the liquid. Yet, even if these values are not taken into account, the 

 differences are very remarkable, especially with quinoline, and the 

 agreement with Wiebe's result is also not quite satisfactory. Part of 

 these differences may be due to impurity in the liquids used in the 

 jacket. Pains were taken at the beginning of our experiments to 

 have them quite pure, but as the values show, apparently, a tendency 

 to rise, it may be that continuous boiling produced slight decomposi- 

 tion. In the case of bromnaphthalene this is more than possible. If 

 more time had been at our disposal, we should have tested the purity 

 of our substances during the operations. As it is now, it would be 

 unwise to draw conclusions from our figures about the exact beha- 

 viour of any of the gases used at high temperatures. The coefficients 

 of expansion between 0° and 100° found for argon and helium agree 

 very well with the values usually found for gases, and there is no 

 * < Chem. Soc. Journ.,' vol. 47, p. 640; vol. 55, p. 483. 



