297 
ation the pressures of the volumes close to the necks m, and m, 
were measured, using the manometer as an indicator. For this two 
of the telescopes of the large Société Genevoise cathetometer were 
focussed upon the menisci in the volumenometer and manometer, 
and the heights were read each time from the standard metre S. 
In an identical fashion measurements were made with a smaller 
quantity of gas in the necks m,, m,, and m,. 
For further experimental conditions and precautions reference may 
be made to Comm. No. 121, § 4 and 5 and also to my dissertation, 
which is to be published shortly. 
§ 3. Calculation and values of pva. 
The final value of the gas density for each of the two series of 
measurements, each with its own definite quantity of gas, was 
obtained by means of equation (I) from the observed final pressure 
after the application of the correction necessary for the small differ- 
ence between 20°C. and the temperature at which the measurements 
were made. The pressure coefficient used was 0,0036627 (Comm. 
N°. 60). On account of the smallness of the temperature difference 
for which a correction has to be applied no correction is needed for 
the dependence of this pressure coefficient upon the pressure. The 
observed volumes v4 for each measurement follow from the v4’s 
obtained from the final density and from the ratio of the volumes 
in each series measured at 20°C. to the final volume. Table I gives 
TABLE I. H;. Values of puy 
= 
No. t | P | da calc. | pu obs. | O—C 
| | | 
1 [209 C.) 0.46780 0.43603 1.07278 — 0.00009 
2 > 0.58113 0.54162 1.07295 + 0.00001 
3 > 1.12867 1.05161 1.07328 
| . 
RE 1209 CT} 0.16310 0. 15205 1.07247 — 0.00021 
2 » 0.20258 0.18885 1.07248 — 0.00022 
3 > 0.39313 0.36645 1.07282 
the values of pv4,and those of d4 as calculated from p by means 
of equation (I). 
20 
Proceedings Royal Acad. Amsterdam. Vol. XV. 
