616 
MR. J. BROUGHTON ON A CERTAIN EXCRETION OE 
The above conclusions led to an extension of the observations. As in the above case 
the gas was evolved under diminished pressure, ex- 
periments were tried in which the eudiometers con- 
taining the bark floated in vessels containing mer- 
cury, so that the gas was evolved under a slight 
increase of pressure. The gas, however, was given 
off in about the same proportions, and the floating 
eudiometers gradually rose. Other trials showed 
that though the slicing of the bark at first facili- 
tated the evolution of gas, after seven days the 
amount was the same, whether the bark was put in 
whole or cut up into pieces. 
In order to determine the amount and compo- 
sition of the gas given off by the bark at different 
times, it was evidently necessary to operate upon 
a larger quantity than 5 grms. The plan was 
adopted of placing 47 grms. in a bottle connected 
with a Sprengel’s air-pump (fig. 1) ; the precaution 
recommended by Frankland * being taken — namely, 
that of immersing all joints in liquid, to preclude 
any possibility of leakage. The bottle of bark was 
at first carefully exhausted, and allowed to remain 
so for six hours, and after that lapse of time again carefully exhausted, so that the gas 
evolved from the bark might sweep every trace of adventitious gas that might be pre- 
sent. These operations were completed at dusk of evening. Subsequently the gases 
evolved were pumped off every twelve hours, and collected in a eudiometer over mercury, 
measured, and analyzed. The following Table gives the results, in cubic centimetres, 
corrected for temperature, pressure, and moisture. 
nQ 
Gas evolved at night. 
Gas evolved by day. 
Total gas. 
C0 2 . 
N. 
Total gas. 
C0 2 . 
N. 
1st 
day 
18-22 
17*51 
o-7i 
26-07 
25-66 
0-41 
2nd 
21-93 
21-41 
0-52 
19-40 
18-90 
0-50 
3rd 
15-84 
15-51 
0-33 
16-23 
16-02 
0-21 
4 th 
13-74 
13-30 
0-44 
13-23 
13-06 
0-17 
5th 
11-57 
11-40 
0-17 
12-17 
12-09 
0-08 
6th 
JJ 
9-28 
9*28 
0-00 
12-94 
12-94 
0-00 
7th 
» 
7*39 
7*39 
0-00 
10-72 
10-72 
0-00 
8th 
» 
8-50 
8-50 
0-00 
9-14 
9-14 
0-00 
9th 
» 
7-44 
7*44 
0-00 
8-30 
8-30 
0-00 
10th 
4-51 
4-51 
0-00 
5-21 
5-21 
0-00 
11th 
» 
3-20 
3-20 
0-00 
3-12 
3-12 
0-00 
12th 
» 
3-47 
3-47 
0-00 
3-93 
3-93 
0-00 
13th 
1-69 
1-69 
0-00 
2-04 
2-04 
0-00 
14lk 
1-50 
1-50 
0-00 
2-13 
2-13 
0-00 
* Journal of tlie Chemical Society, 2nd series, vol. vi. p. 90. 
