584 
PROFESSOR GRAHAM ON THE MOTION OF GASES. 
The time of effusion also of the mixture of carbonic oxide and oxygen in equal 
volumes is obviously the square root of the density of the mixture of the two gases : 
Observed time of mixture . . . . TO 188 
Calculated time of gases . . . . TO 182 
The observed time of effusion of the mixture being within one thousandth part of 
the calculated time. 
5. Effusion of Carbonic Acid, Air, and of mixtures of Carbonic Acid and Air, at 
different pressures, by Plate B. 
The arrangements continued the same as in last experiments ; barometer 29 58 in. ; 
thermometer 49°. 
Table IV. — Effusion. 
Gauge barom. 
in inches. 
Air. 
Carbonic acid. 
First mixture, 
75C0 2 +25 air. 
Second mixture, 
50CO 2 -f 50 air. 
Third mixture, 
25C0 2 +75 air. 
I. 
II. 
I. 
II. 
I. 
II. 
I. 
II. 
I. 
II. 
// 
// 
// 
// 
// 
// 
// 
// 
// 
28 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
20 
121 
121 
145 
146 
141 
140 
135 
134 
128 
128 
12 
123 
123 
150 
149 
143 
143 
137 
137 
131 
131 
8 
69 
70 
83 
84 
81 
80 
76 
77 
74 
73 
4 
85 
84 
103 
103 
98 
99 
95 
94 
90 
90 
2 
58 
59 
71 
70 
68 
67 
64 
64 
61 
61 
456 
457 
552 
552 
531 
529 
507 
506 
484 
483 
Comparing again the times in the two divisions of the scale adopted in the pre- 
ceding tables : 
Time in Seconds. 
Gauge barometer. 
Air. 
Carbonic acid. 
Mixture I. 
Mixture II. 
Mixture III. 
From 28 to 12 inches. 
244 
295 
283-5 
271-5 
259 
From 12 to 4 inches. 
154 
187 
179 
171 
163-5 
Time of Effusion, time of Air = 1 . 
Gauge barometer. 
Carbonic acid. 
Mixture I. 
Mixture II. 
Mixture III. 
Observed. 
Calculated. 
Observed. 
Calculated. 
Observed. 
Calculated. 
Observed. 
Calculated. 
From 28 to 12 inches. 
From 12 to 4 inches. 
1 2090 
1-2143 
1-2365 
1-2365 
1-1618 
1-1818 
1-1127 
1-1245 
1-0618 
1-0647 
The calculated number for carbonic acid (E2365) is the theoretical time, or square 
root of the density of the gas ; the calculated times for the mixtures are also the 
square roots of the respective gravities of those mixtures. 
The times of effusion of carbonic acid compared with air do not therefore differ 
