Page:Proceedings of the Royal Society of London Vol 69.djvu/378

362 0.127 c.c., was therefore approximately at the temperature of the room. When the temperature of the flask and its contents became stationary the stopcock was closed, the flask removed, and after heating up to the temperature of the room, weighed against the B flask and any further necessary counterpoise b. The weight of oxygen vapour in the flask at its boiling-point was thus equal to a + b, subject to the corrections which have been indicated.

To the five sources of error or correction indicated above, there remains to be added that due to additional buoyancy of the air during the weighing of the flask, when filled with oxygen at its boiling-point, for these weighings were made at the temperature of the room, which would cause a rise of pressure in the flask and therefore expansion of its volume. But this error was so small that it could safely be neglected.

As the intention was not only to ascertain the density of oxygen and nitrogen at their respective boiling-points under atmospheric pressure, but also under diminished pressure, experiments were made with nitrogen at ordinary temperatures and at pressures varying from about one-sixth of an atmosphere to ordinary pressures, in order to find the range of variation in the results with the 316 c.c. flask to be used in the subsequent low-temperature experiments. In the follow- ing table are details of these observations, and the results reduced according to the ordinary gaseous laws.

Table I. Density of Nitrogen, ordinary Temperature.

No.

Pi-

TI.

p. a.

b.

V.

d.

fo

mm.

mm.

gramme

gramme

742-0

15-5

742-0

0-37

-0-0022

315 -973

0-001168

-001265

2

742-0

15-5

742 -0

-3668

-o-ooi

315-973

-001162

-001258

3

742-0

16-0

742-0

0-367

-0-0015

315-973

0-001161

-001259

4

751-0

16-5

281-3

0-371

-0 2328

315 -913

-000442

0-001265

5

751-0

16-5

284-2

0-371

-0-231

315 -913

-000447

-001269

fi

751-0

17-0

268-5

0-371

-0-239

315-911

-000422

0-001269

7

753-0

17-5

176-2

-3705

-0-2850

315 -899

-000275

0-001262

where p\ = barometric pressure at the time of observation,

T! = temperature of the room at the time of observation,

p pressure of the nitrogen vapour in the flask during the

experiment,

a, b as defined before, V =the volume of the flask corrected for temperature and

compression,

d = the calculated density at TI and pressure p, do = the value of d reduced to 0" and 7 80 mm. by the ordinary gaseous laws.