412 
The temperature of the bath was furnished by the determinations 
themselves. See § 6. 
§ 5. Calibration, Constants and calculation of corrections. 
a. Pressures. 
The corrections, and in particular the optical corrections, for the 
apparatus have already been discussed in part in Comm. N°, 121a. 
The pressures were always reduced to the normal atmosphere of 
45° N. For this the value of the Leiden atmosphere, 75.9463), was 
used. The following corrections were applied to the pressures : 
1. A temperature correction for the inequality between the tem- 
peratures of the mercury in the manometer and in the volumeno- 
meter (Comm. N°. 1214). 
2. A correction for the standard meter which is 999.91 mm. at 
0°C. (Comm. N°. 70). 
3. An optical correction for the refraction of light by the glass 
windows (Comm. N°. 1214) and by the manometer tube. 
4. A correction for the capillary depression. These corrections 
were tabulated for various widths of tube, being obtained from 
Kenvin’s graphical construction and from LOHNSTEIN's *) formula. 
5. A correction for KNuDsEN’s transpiration pressure *). 
6. A correction, where necessary, for the pressure of the air 
column between the lower barometer meniscus and the manometer 
meniscus. 
7. A correction for the aerostatical difference between the pressure 
in the volumenometer and that in the piezometer was neglected. 
A discussion of the degree of accuracy attained in the determination 
of the pressure has already been given in Comm. N°. 121a. 
h. Volumes. 
Reference may be made to Comm. N°. 121a for the calibration 
of the volumenometer. 
The volumes as measured were always corrected at their cali- 
bration temperature. This correction was always. very small. 
A correction for the compression of the glass vessels was applied 
by means of the formula 
Jy, 3] (1 —ti) (pi Pe) 5 
EA, 
V Se AS, d 
1) This value has been calculated with the number for the gravity at Leiden 
used in Comm. N'. 60, Sept. 1900, p. 304, and gnorm = 981,625 according to 
Suppl. N°. 23, “Einheiten” a. (Note added in the translation). 
2) F. Lonnstetn. Ann. der Physik (4) 33 (1910), n°. 2. 
3) M. Knupsen. Ann. der Physik (4) 81 (1910), n°. 3. 
