PROFESSOR GRAHAM ON THE MOTION OF GASES. 
583 
of 50 nitrogen + 50 oxygen, or square root of the specific gravity of that mixture, 
is 1*0191, the observed rate 1*0185; of 25 nitrogen + 75 oxygen, the mean rate is 
1*0354, the observed rate 1*0391 ; of 75 nitrogen + 25 oxygen, the mean rate is 
1*0025, the observed time 1*0041, in the range between 28 and 12 inches of the gauge 
barometer. Lastly, the particular mixture forming atmospheric air has already been 
seen to have the rate corresponding with its specific gravity or its composition. It 
may hence be inferred that any mixture of oxygen and nitrogen will possess the 
average rate of effusion of its constituent gases. 
4 . Effusion of Air, Carbonic Oxide, Oxygen, and of a mixture of Carbonic Oxide and 
Oxygen at different pressures, by Plate B. 
The carbonic oxide was prepared according to Mr. Fownes’s process, by heating 
oil of vitriol upon ferrocyanide of potassium : the gas was collected, as a measure of 
precaution, over alkali. 
The arrangements were similar to the last ; barometer at 29*29 inches, thermo- 
meter 52°. 
Table III. — Effusion. 
Gauge barometer in 
inches. 
Air. 
Carbonic oxide. 
Oxygen. 
Mixture of 
50 carbonic oxide + 50 oxygen. 
I. 
II. 
I. 
II. 
I. 
II. 
I. 
II. 
// 
// 
// 
/✓ 
// 
// 
28 
0 
0 
0 
0 
,0 
0 
0 
0 
20 
118 
119 
116 
117 
125 
126 
121 
121 
12 
120 
120 
118 
117 
126 
126 
123 
122 
8 
67 
66 
66 
66 
71 
71 
68 
68 
4 
81 
82 
80 
81 
86 
86 
83 
83 
2 
56 
56 
55 
55 
60 
60 
58 
58 
442 
443 
435 
436 
468 
469 
453 
452, 
The passage of the gases is somewhat quicker throughout than in the preceding 
experiments with the same plate, but the ratio between their velocities remains con- 
stant. 
Comparing again the same portions of the scale, we have — 
Gauge barometer. 
Time in seconds. 
Time, air = 1. 
Air. 
Carbonic 
oxide. 
Oxygen. 
Mixture. 
Carbonic 
oxide. 
Oxygen. 
Mixture. 
From 28 to 12 inches 
238-5 
148 
234 
146-5 
251-5 
157 
243 
151 
0-9811 
0-9898 
1-0545 
1-0608 
1-0188 
1-0202 
From 1 2 to 4 inches 
Taking 0*96779 as the specific gravity of carbonic oxide, the square root is 0*9838, 
which corresponds closely with the observed time above, being intermediate between 
the times for the two different portions of the scale. 
