(779) 
These are given in the following table. In column A are the 
calculated values of the pressure?) at the various readings obtained 
from Ist the volume determined by the previous mercury calibration, 
2nd a mean value of the normal volume of the enclosed gas calcu- 
lated from the comparison with the standard manometers, the 
calibrations being all reduced to 20°.0 C. so that the isotherm 
determined by SCHALKWIJK could be directly employed. As the 
deviations in temperature were some times considerable the reductions 
were made with the value for a, = 40 given above. 
Column B gives the mark of the standard manometer used. AJIT 
and AIV are the tubes /1/ and JV of Comm. N°. 70, O the 
open manometer of Comm. NO. 44. 
As the temperature differences were here greater than with the 
other determinations the numbers have not the same relative value 
as these of the other series. 
Column C gives the pressure on the gas in the manometer obtained 
by applying all corrections for capillary depression level tubes ete. 
to the readings of the standards. 
Column D gives the differences between columns A and C and 
represents some error in calibrations or standardisations. We assume 
that the values given in column C are the correct values of the 
pressure and apply a small correction to A to make the resulting 
differences as small as possible. 
A correction to the volume of the following form ®) appears to give 
the most satisfactory results. 
If V is the volume as formerly calculated V' the new volume and 
R the reading in cms 
v= V'i— V = — 0.34 + (100 — R) 0.0109 mm? 
P' is then calculated for each case with this new value of V'. 
The differences between the new pressures thus calculated for 
column A and colume C are given in column E. 
1) The difference bétween these values and those in the Dutch text is due to an 
improved calculation of the calibration. 
2) A systemic correction is here applied in place of the former empirical one. 
