136 DR. A. J. EWART ON THE EVOLUTION OF 
hydrogen through for 10-15 minutes, no perceptible oxygen can 
be detected in the hydrogen enclosed when analysed. 
With Bacillus brunneus the following results were obtained 
(temp.=20° C.) :— 
| | 
18 e.c. 
20 c.c. 3ec 1 ,, 16 , |Shrs. HgCl,, then H| 02 Trace.) 0:006 cc 
| and sealed. 
6 hrs. HgCl,, then H| 0-18) 0:38 | 0018 ce. 
and sealed. | 
* The Bacteria if obtained from agar-plate cultures are weighed direct 
moist ; if from bouillon, the superfluous fluid is drained off and the mass after 
drying with filter-paper weighed. 
t The amount of CO, is disproportionately small, owing to a large part 
remaining dissolved in the enclosed fluid. 
From the above it appears that B. brunneus can evolve per 
gramme of dry weight from 02 to 045 c.c. of oxygen, which is 
a quite appreciable amount. Later results gave, however, a lower 
value. If the Bacteria remain living, this evolved oxygen is 
used up again. If HgCl, is added, the pigment is so altered 
that it loses its power of occluding oxygen, and the same also takes 
place when heated to 90° C.-100? C. for some time, and that 
more rapidly if heated in a bouillon-culture than in pure water. 
The following experiment shows that the oxygen formed 5 
actually derived from the bacterial eulture, and is not due to any 
error in the method employed:— Through a tube containing 
l gramme of Bacteria to 18 c.c. of fluid and 3 c.c. of gas, Hs 
passed for 5 minutes, and then a sample of the gas issuing through 
the distal tube is colleeted over Hg and analysed. It contained 
0:6 per cent. CO, and 0*5 per cent. oxygen; a second sample, 
O evolved 
Amount | | Of . " per grm. 
of Fluid. Of H. Bacteria *. Time. Condition. O. CO,. moist weight 
of Bacteria. 
—]1 
| p.e. | pe | 
18 c.c. | 3 c.c.| 2 grms. | 5hrs. HgCl, after sealing. | 21-1 | 0:59 | 0316 c.e. 
| 
18 c.c. | 3cec.| 2 » 5 , | Living and normal. | 178 | 0:42 0:267 c.c. 
18 c.c. | 3cc. | 2 " 5 , | HgCl, beforesealing. 20:3 | OSL 0:309 c.c. 
| 
18 c.c. Sec.) 2 » 6 ,, | HgCl, after sealing. | 900 | 0'66 0-45 cc 
20 c.c. | 3ec. 1 grm. |26 ,, | Living and normal. | 00 | 172t| 00 ce 
