604 
PROFESSOR GRAHAM ON THE MOTION OF GASES. 
The numbers for air, hydrogen and carbonic acid accord well with those obtained 
by the other capillaries. The small addition of 5 per cent, of air to hydrogen has a 
surprising effect in retarding the transpiration of that gas. The mean rate of such a 
mixture, calculated from the rates of air and hydrogen separately, is 0*4625, whereas 
the actual rate is 0*5264. The rate of the mixture should only be increased by 
0*0228, whereas it is really increased by 0*0840. Hence the effect of 5 per cent, of 
air in retarding the rate of hydrogen is nearly four times greater than it should be 
by calculation. The experiment shows the effect which a small amount of impurity 
must have in deranging the transpiration rate of that gas. I shall return again to 
this point under the subject of the transpiration of mixed gases. 
Table XVIII. — Transpiration by Capillary H into a three-pint jar. 
Barom. 30‘3 — 30*242. 
Gauge barometer in inches. 
Oxygen. 
Nitrogen. 
Carbonic oxide. 
Air. 
I. 
II. 
I. 
II. 
I. 
II. 
I. 
II. 
6l°-5 
6l°-5 
6l°-5 
6 1°*5 
6l°-5 
6l°-5 
6l°-5 
6l c -5 
28 
0" 
0' 
0 ' 
0 ' 
0 ' 
0" 
0" 
0 ' 
24 
238 
239 
208 
208 
207 
207 
214 
214 
20 
253 
253 
220 
221 
220 
220 
229 
229 
12 
614 
614 
536 
533 
532 
533 
552 
550 
8 
434 
434 
378 
376 
376 
377 
389 
392 
6l°-75 
6l°-75 
62° 
62° 
62° 
62° 
62° 
62° 
From 28 to 8 inches 
1539 
1540 
1342 
1339 
1335 
1337 
1384 
1385 
Mean Results. 
Gauge barometer. 
Nitrogen. 
Carbonic oxide. 
Air. 
From 28 to 24 inches < 
From 24 to 20 inches < 
From 20 to 12 inches < 
From 12 to 8 inches • 
Time in seconds 
Time of oxygens 1 ... 
r Time in seconds 
Time of oxygen=l... 
f Time in seconds 
Time of oxygen =1... 
f Time in seconds 
Time of oxygen =1... 
208 
0-8721 
220-5 
0-8715 
534-5 
0-8705 
377*5 
0-8698 
207 
0*8679 
220 
0-8695 
532*5 
0-8673 
376-5 
0-8675 
214 
0-8972 
229 
0*9051 
551 
0-8974 
390-5 
0-8998 
From 28 to 8 inches 
f Time in seconds 
^ Time of oxygen = 1... 
1340-5 
0-8707 
1336 
0-8678 
1384-5 
0-8993 
In the preceding table, a comparison is made between two gases, nitrogen and 
carbonic oxide, of which the theoretical specific gravities are the same, namely 
0*8750, while the mean rate of nitrogen, from 28 to 12 inches, proves to be 0*8707, 
and that of carbonic oxide 0*8678, which is a pretty close approximation. In several 
other experiments with these gases, a slight difference in their coefficients of transpi- 
ration was observed, carbonic oxide having always the smaller number : the difference 
generally approached 0*0040. It is not at all impossible, however, that these gases 
