View report page

46
cause is usually to be found in the presence of an excess of moisture and also of organic pabulum.
Although the number of bacteria capable of forming spores in soils is peculiarly great, it is
probable that the majority of these form spores only when there is a deficiency in the amount of
liquid organic pabulum and when the physical conditions are unfavourable.
It is, perhaps, permissible to hazard the conjecture that an increase (actual or relative) in
the number of spores of bacteria in effluents from bacterial beds is possibly a favourable sign. Yet
surmises such as the above are best received with caution, especially as they are to some extent
founded on a comparison between a liquid (sewage) in the one case and a solid (soil) in the other.
Certainly, however, it is a point worth noting that in soils the ratio of spores to bacteria is
commonly more than 1: 10 and in sewage less than 1: 10,000. Waters, it may be added, differ
rather widely in this respect, but they always approximate much more closely to the ratio found
in sewage than to that found in soil.
(c) Number of Bacteria causing Liquefaction of Gelatine in 1 c.c.
Date.
Crossness
crude sewage.
Effluent from 4 ft.
coke-bed.
Effluent from 6 ft.
primary
coke-bed.
Effluent from 6 ft
secondary
coke-bed.
1898.
co
©
be
ce 1
Ph
1
o )
A 1
a
■s 1
§
&
A
a>
TD
U
o
Q*
PH
c
o
o
©
May 11
400,000
1,300,000
...
18
100,000
700,000
...
25
900,000
700,000
...
June 9
1,400,000
200,000
...
15
800,000
1,100,000
...
22
900,000
600,000
...
July 20
1,700,000
1,000,000
...
27
900,000
...
300,000
...
August 4
400,000
500,000
...
...
9
1,100,000
200,000
...
19
600,000
400,000
24
600,000
1,100,000
...
September 14
700,000
700,000
21
1,200,000
1,100,000
28
1,200,000
1,200,000
October 5
2,400,000
600,000
...
12
700,000
1,200,000
...
21
1,000,000
...
1,000,000
...
26
700,000
...
500,000
November 9
1,900,000
1,400,000
...
16
1,600,000
...
1,500,000
...
23
900,000
...
...
400,000
30
900,000
500,000
...
December 7
1,400,000
...
900,000
14
1,400,000
...
...
1,600,000
21
2,200,000
600,000
...
...
Averages...
1,076,923
(26 samples)
806,666
(15 samples)
837,500
(8 samples)
833,333
(3 samples)
Percentage reduct ion (as compared
with the raw sewage)
25 per cent.
22 per cent.
22 per cent.
be ® 1 A ® -4^ /
5 |
® m J5 6 r3
0 " 8 &. o P .
s a-e
" 5 p cs . s 0)
^ g <0 ^
o v O o i
CJ « -12 P, *0
|.a s a
6 I 2 '■§ 'S ® §
g-§,§ s.SiS s
® J t
< I
986,666 -)
(15 samples cor- [
responding to (
4 ft. samples) J
806,666
18 per cent,
reduction
1,275,000 \
(8 samples cor- 1
responding to >
6 ft. primary I
samples)
C 837,500
■; 34 per cent.
( reduction
1,000,000 \
(3 samples cor- I
responding to >
6 ft. secondary I
samples) ]
( 833,333
< 16 per cent.
(. reduction
The table shows that the number of liquefying bacteria in the crude sewage (26 samples),
the effluent from the 4-foot coke-bed (15 samples), the effluent from the 6-foot primary coke-bed
(8 samples), and the effluent from the 6-foot secondary coke-bed (3 samples) averaged 1,076,923,
806,666, 837,500, and 833,333 per c.c. respectively. The percentage reduction in the number of
liquefying bacteria in the effluents being respectively 25, 22, and 22. The average number of
liquefying bacteria in the 15 samples of crude sewage corresponding to the 4-foot coke-bed
effluents was 986,666. In the 8 samples corresponding to the 6-foot primary coke-bed effluents