( 954 ) 
k,—a with high pressure oxygen using the auxiliary compressor and 
the volumenometer. 
The equation that is necessary for the reduction of the volume 
of a quantity of gas measured in ce. in the volumenometer at a 
certain pressure and temperature to the normal volume N (at O°C, 
and 760 mm.) of that quantity expressed in c.c. may also be obtained 
from the equation for ordinary temperature. One can easily see from 
the numbers given above that in these circumstances CW) is negligible, 
so that 
oy pV 
Aa, (1 + aard) (l + Bp)’ 
for which all the data have been found above. Let us use it to 
determine the pressure coefficient for oxygen between O°C. and 20°C. 
and for a pressure of 1 atm. at 0?C. We get 0.0036746 a number 
that agrees well with that given by Joy’). 
For the normal density of oxygen we have taken the mean of 
the values®) given by Lrepuc, RayrriGn, and Morey: 0,00142876, 
0,00142905, and 0,00142900, viz: 0,00142894. 
For the corrections that are applied in the calculation. of the 
volumenometrie measurements which give p, W,/, we may refer to 
the Communications already quoted N°’. 84, 88, 92 and to the 
Communication that we mentioned in $ as soon to appear. The 
accuracy of those measurements is greater than that which we were 
able to reach with our dilatometer so that the mass data may be 
taken as certain. As an example we give the following results 
obtained by each of us measuring the same mass twice: 
11 Nov. 1.74448 
PN 1.74432 
sous 1 TAAAD 
‘le eee ALS 
12e AAD 
1.74449 
1.74444. 
Hence we can be pretty certain of an accuracy of L in 4000 in 
the mass. 
To get an idea of the accuracy with which equilibrium to 
which the measured quantity referred was actually realised, 
1) Maxower and Nopre's measurements are doubtful. They give = 0.0036655 
for p =O instead of 0.0036618, a value that is certainly too high. 
2) Dante. Berruetor, Ztschr. f. Electrochem. 1904 p, 621. 
