Page:Proceedings of the Royal Society of London Vol 69.djvu/381

Rh Table III. Density of Oxygen Vapour at its Boiling-point under Diminished Pressure.

No.

Pi- T,.

P-

.

b.

V.

d.

V.

mm.

mm.

gramme

gramme

1

741 -8 18 -5

287-0

-3693

0-1315

314-340

-001588

625 -74

2

741-8 18-5

281-5

-3695

0-1315

314-339

0-001607

622 01

3

746 5 20-0

279-0

-3690

' 1 290

314-338

-001588

629-41

4

746-5 20-0

310-2

-3690

0-1880

314 -342

0-00177t5

562 -95

5

746 -5 19 -0

159-4

-3690

-0850

314 -323

-000907

1101 '46

In reducing these observations the following corrections were involved: a correction of 0'0014 gramme to 0-0015 gramme due to imperfect exhaustion of the A flask while being weighed as empty ; the correction due to the neck of the flask between the mark and the stopcock not being at 90 -5 amounted to 0-00003, 0-00007 gramme and was practically negligible ; the volume of the flask, which, when corrected for temperature, was 314-398 c.c., had to be further corrected for excess of external pressure over internal pressure by amounts varying from 0*0551 c.c. to 0'0742 c.c. If the first three experiments are averaged (the pressures being so near), the weight of a litre of oxygen at 90 0< 5 absolute under a pressure of 282*5 mm. would be 1'5982 grammes. The ratio of this density to the value previously found for one atmosphere pressure, viz., 4-42 grammes, is 2'765, and the ratio of the pressures is 2-690. It appears that the ratio of the change of density of the vapour of oxygen at 90'5 absolute, under variable pressure, is greater than the ratio of the change of pressure. It is clear, however, that it would be necessary to work upon a larger scale in order to get satisfactory vapour densities at low tem- peratures under pressures below that of the atmosphere.

The following table gives the observations on the density of nitro- gen vapour at the boiling-points of liquid oxygen and liquid air respectively ; the first two were made in oxygen, the last four in air. The symbols used are the same as before, except that d is the calculated density at T absolute and 760 mm. and v is l/d.

Table IV. Density of Nitrogen Vapour at the Boiling-point of

Oxygen.

No.

p=p\- T,.

a.

b. d. v.

T.

mm.

gramme.

gramme. <

1

771 -8 17 '5

-3875

0-8555 0'00;!9021 256 '27

(90-5)

2

773 -0 17 -0

0-385

-8555

'003885

257 -39

(90-5)

3

777-2 16-0

-3885

'9575

-004192

238-53

84-05

4

777-3

16-5

0-3885

0-9500

-001168

239 -90

84-54

5

777-3

16-5

0-3885

942

0-004143

241-34

85-04

6

777-3

16-5

0-3845

-9235

-004073

245*49

86-50