698 
PROFESSOR GRAHAM ON THE MOTION OF GASES. 
carbonic acid into a perfect vacuum would certainly approach still more nearly to 
0*75 ; for the rate of transpiration of that gas appears, in the case of the present 
capillary, to become slower with the increase of pressure. It will be seen hereafter 
that the gases deviate very sensibly at low pressures from the empirical coefficients 
of transpiration which have been named, becoming slower in their passage with 
reference to oxygen, as is here observed of carbonic acid. This deviation appears to 
be connected with excessive resistance, whether arising from the smallness of the 
capillary opening or diminished pressure. 
With the view of observing the effect of alterations in the position and dimensions 
of a capillary, experiments were now made with this tube, (1) in an inverted position, 
so that the gas entered by the narrow and escaped by the wide end, and (2) after 
being reduced to half its original length. 
Capillary B reversed . — The passage of gas through this tube was nearly three times 
more rapid in the new direction, 1 cubic inch of air being now transpired into a 
vacuum in 12*6 seconds. The length of the tube and resistance to passage through 
it are therefore nearly the same as in capillary A; but while the latter was of uni- 
form bore, the present capillary is highly conical. 
Table XII. — Transpiration byCapillaryB reversed into a one-pint jar. Barom.30T3. 
Gauge barometer in inches. 
Air. 
Oxygen. 
Hydrogen. 
Carbonic acid. 
I. 
II. 
III. 
I. 
II. 
III. 
I. 
II. 
I. 
11 . 
III. 
59 ° F. 
59° F. 
59° F. 
61° F. 
6l°-5F. 
6l°-5F. 
62° F. 
62° F. 
28 
0" 
0" 
0" 
0" 
0" 
0" 
0 " 
0" 
0" 
O' 
O'' 
' 20 
149-5 
144-5 
145 
160 
160 
160 
69 
69 
127 
126 
126 
12 
173-5 
177*5 
178 
198 
196 
196 
86 
85-5 
154 
153 
152 
4 
318 
318 
317 
352-5 
353-5 
353-5 
157-5 
157-5 
268-5 
267-5 
268-5 
2 
190 
189-5 
192-5 
216 
216-5 
215 
96 
96-5 
154-5 
155 
156-5 
From 28 to 12 inches ... 
323 
322 
323 
358 
356 
356 
155 
154-5 
281 
279 
278 
From 28 to 2 inches... 
831 
829-5 
832-5 
926-5 
926 
924-5 
408-5 
408-5 
704 
701-5 
703 
Mean Results. 
Gauge barometer. 
Air. 
Hydrogen. 
Carbonic acid. 
From 28 to 12 inches • 
From 12 to 4 inches < 
From 4 to 2 inches • 
f Time in seconds 
Time of oxy gen = 1 . . . 
r Time in seconds 
Time of oxygen=l... 
f Time in seconds 
Time of oxygen = 1 . . . 
322 
0-9024 
317-7 
0-8994 
190-7 
0-8836 
154-75 
0-4338 
157*5 
0-4459 
96-25 
0-4459 
279-33 
0-7831 
268-16 
0-7595 
155-33 
0-7197 
From 28 to 2 inches - 
r Time in seconds 
Time of oxygen = 1 . . . 
831 
0-8978 
408-5 
0-4413 
702-83 
0-7594 
The coefficients of air and hydrogen, although still corresponding very closely with 
the numbers 0 9038 and 0*4375, begin to exhibit a sensible variation in different parts 
of the scale. The variation in carbonic acid is considerable, amounting to 0*0634, 
and the divergence is on both sides of the empirical number 0*75. 
