PROFESSOR GRAHAM ON THE MOTION OF GASES. 
355 
The length of the capillary K being now reduced to 13*12.5 inches, air was found 
to enter so as to depress the attached barometer from 28*5 to 25*5 inches in 284 
seconds, and from 28*5 to 23*5 inches in 472 seconds ; thermometer 56° and baro- 
meter 29*758 inches. To obtain longer times, the two-pint jar, used as the aspirator- 
jar, was replaced by the six-pint jar, which last gives an available vacuous space 
estimated at 201*78 cubic inches. The fall of the attached barometer continued to 
be observed from 28*5 to 23*5 inches. 
(1.) The times of air were 1348 and 1353 seconds; the times of oxygen 1498 and 
1499 seconds ; thermometer 58° and barometer 29*628. The means give 0*9013 as 
the transpiration time of air. 
Observing only through the smaller range of the attached barometer, namely, from 
28*5 to 25*5 inches, the following results were obtained : — 
(1.) The time of air was 809,809 seconds. 
(2.) The time of carbonic oxide was 780 and 779 seconds. 
(3.) The time of hydrogen was 399, 400 and 398 seconds. 
(4.) The time of carbonic acid was 658 and 657 seconds. 
The experiments were made successively in the order in which they are stated, 
with the thermometer at 59° and the barometer from 29*450 to 29*422. The results 
may be given as follows : — 
Table III. — Transpiration times. 
Air=l. 
Oxygen = 1. 
Carbonic oxide 
0-9635 
0-4932 
0-8127 
0-8671 
0-4438 
0-7314 
Hydrogen 
Carbonic acid 
The transpiration times of the second column are obtained by multiplying the 
times of the first column by 0*9, a number which represents the time of air with suf- 
ficient accuracy, the time of oxygen being 1. It will be observed that the number 
for carbonic oxide remains wonderfully constant for all lengths of K ; that the num- 
ber for hydrogen 0*4438 now approaches more nearly to 0*4375, probably as nearly 
as a slight impurity of the gas, resulting from its short contact with water, would 
admit ; and that the number for carbonic acid 0*7314, is still low, and does not differ 
much from 0*7272. 
In a second series of experiments, which need not be detailed, numbers corre- 
sponding closely with the preceding were obtained ; namely, 0*9003 for air, 0*8656 
for carbonic oxide, and 0*7336 for carbonic acid. 
The capillary K was reduced to 8*75 inches, or to one-sixth of its original length, 
the six-pint jar being retained as the aspirator-jar, and the fall of the attached baro- 
meter observed from 28*5 to 23*5 inches. 
(1.) The times of air were 933 and 933 seconds; of oxygen 1036, 1036 and 1037 
