596 
PROFESSOR GRAHAM ON THE MOTION OF GASES. 
It is a question how far this variation in the ratio is owing to the action of effusion ; 
the time of effusion of this gas being only 0*25, referred to oxygen as unity, while its 
time of transpiration is 0*4355. The influence of effusion upon the rate of passage is 
likely to be most considerable when the pressure is greatest ; and that of transpira- 
tion, on the contrary, most considerable when the resistance to the passage of the 
gas is greatest and the pressure least, that is, in the lower part of the scale. 
It may be observed that the transpiration time of hydrogen does not differ far 
from 0*4375, which is one-half of the transpiration time of nitrogen, calculated from 
the experiment on air, or seven-sixteenths of that of oxygen. 
Carbonic acid appears to be much more quickly transpired than oxygen, although 
denser than that gas in the ratio of 11 to 8 ; but the effusion time of carbonic acid 
being slow, any influence of effusion will increase the time of transpiration of this 
gas, — the reverse of what occurs with hydrogen. The transpiration time of carbonic 
acid varies considerably at different pressures, being slower by 0*0535 at the upper 
than the lower part of the scale. An approach to 0*75, or twelve-sixteenths of the 
time of oxygen, may be noted at present in the rate of this gas. 
The transpiration rate of carburetted hydrogen appears to be affected by an error 
of observation in the middle part of the scale ; but its rate is slower at the upper 
part than at the lower, to the extent of 0*0211. This is also in accordance with the 
assumed influence of effusion, the effusion time of this gas being greater than its trans- 
piration time. The transpiration time of carburetted hydrogen is not in direct pro- 
portion to its gravity, which is 0*5, or one-half of that of oxygen : it approaches more 
nearly to 0*5625, which is nine-sixteenths of the time of oxygen. 
Capillary B. — This glass tube was 31*5 inches in length, of a round bore, but de- 
cidedly conical. It was first placed so that the gas entered the tube by the large and 
escaped by the small opening. When so arranged this tube allowed 1 cubic inch 
of air to pass into a vacuum in 34*3 seconds, or the transpiration was nearly three 
times slower than by A. 
Table X. — Transpiration by Capillary B into a half-pint jar (21*26 cubic inches). 
Barom. 29*17. Temp. 68°. 
Gauge barometer in inches. 
Oxygen. 
Nitrogen. 
Carburetted hydrogen. 
I. 
II. 
I. 
II. 
III. 
I. 
II. 
// 
// 
// 
// 
// 
it 
it 
28 
0 
0 
0 
0 
0 
0 
0 
20 
235-5 
235-5 
209 
205 
205 
133 
133 
12 
289 
290-5 
252 
253 
162-5 
163 
4 
521 
521 
451-5 
453-5 
290-5 
290-5 
2 
290-5 
290 
258 
255-5 
164 
165-5 
From 28 to 2 inches ... 
1336 
1337 
1170-5 
1167 
205 
750 
752 
