415 
in which Z = 6500 a. pai. ae V, == 3.9 em, == CS, 
(See Comm. N°. 88). 
In the calculation of the volumes, the volumes of the mercury 
menisci were taken from the table given by Scnern and Huvse *). 
As regards the accuracy of the volumes measured we may remark 
that a variation of one degree in the temperature causes a change 
of only 1 in 40000 in the volume. The correction for the compres- 
13 JV 
——— for — at the lowest pressure measured (5 cm.) 
10000 Là 
If this correction is applied, the remaining uncertainty is certainly 
lees Hier hy 6s as 
As regards the volume of the mercury menisci as, for instance, 
in the case of 2 = 14.8 mm. where the volume is 179.4 mm” for 
a meniscus height of 1.6 mm., and 192.2 mm’. for a height of 
1.7 mm., the error for heights lying between these two values is 
certainly not so great as 10 mm’. This is certainly negligible in a 
volume which would, at ordinary temperature, be at least 1200 cm’. 
seeing that the volume of the piezometer is 110 em*. and contains 
gas of density from 12 to 20 times the normal. The same may be 
said of the uncertainty in the volume of the dead space. Such 
portions of this as were not separately calibrated with mercury 
(steel and glass capillary, see dissertation DE Haas’ were volumeno- 
metrically calibrated. The total dead space was about 10 em*. An 
error of 1°/, in the calibration or of 3 degrees in the temperature 
causes „an uncertainty of 100 mm”. This is only 1 in 12000 of the 
1200 em”. just mentioned. The volume calibration, however, was 
much more accurate, while, as was stated above, the room tempe- 
rature was kept constant to within a degree. 
These comments are also all applicable to the determinations of 
Comm. N°. 121a. 
The accuracy attained in the calibration of the piezometer was 
greater than 1 in 10000 (ef. dissertation pe Haas). The volume was 
corrected for the temperature of the cryostat by means of the formula 
' t Ae tart Pes 
“=, k En | a + (sr) ros | 
k, = 2843 
BE Ald 
(See Comm. N°’. 955, $1). The error arising from this method can 
only be very small. 
Temperature corrections for the gas in the glass capillary were 
sion gives 
in which 
1) K. ScueeL and W. Heuse. Ann. d. Phys. (4) 33 (1910), n°. 2 
