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