360 
PROFESSOR GRAHAM ON THE MOTION OF GASES. 
gauge tube was a barometer about 70 inches in length, with a vacuum above the 
mercury. The gas was allowed to escape from the condenser through the capillaries 
into the open atmosphere, or into a space containing air, of which the tension was 
preserved uniform, and which formed an artificial constant atmosphere, the time 
being noted which the mercury in the gauge tube of the condenser took to fall 
through a fixed range of 2, 4 or 10 inches, according to the degree of compression. 
The available capacity of the condenser was about 72 cubic inches. 
The resistance of the fine capillary tube of the present bundle was not less than 
400 times greater than the resistance of the finest tubes hitherto used, namely K and 
M, the comparison being made between equal lengths of the different tubes. 
Experiments with eompound Capillary P. 
(1.) Dry oxygen was thrown by a syringe into the condenser till the pressure in- 
dicated by the pressure gauge exceeded, by more than 20 inches, the pressure of the 
external atmosphere. The gas was then allowed to escape from the condenser 
through the capillaries into the atmosphere, and the times noted which the mercury 
of the pressure gauge took to fall from 20 to 15, 10, 8, 6, 4 and 2 inches. 
Table V. — Transpiration of Oxygen. 
Pressure by gauge barometer. 
Experiment I. 
Experiment II. 
Experiment III. 
inches. 
// 
// 
// 
20 
0 
0 
0 
15 
241 
240 
241 
10 
352 
353 
352 
8 
202 
202 
200 
6 
266 
266 
265 
4 
379 
382 
378 
2 
653 
650 
647 
From 20 to 2 inches 
2093 
2093 
2083 
(2.) A similar series of experiments was made on the transpiration of compressed 
air, of which the results are as follows : — 
Table VI. — Transpiration of Air. 
Pressure by gauge barometer. 
Experiment I. 
Experiment 11. 
inches. 
// 
// 
20 
0 
0 
15 
217 
217 
10 
316 
316 
8 
181 
181 
6 
239 
238 
4 
400 
400 
2 
524 
524 
From 20 to 2 inches 
1877 
1876 
Both these last series and the series which follows on carbonic acid were made 
