View report page

9
The principal, if not the only, source of microorganisms
in sewer air, is the air without the sewer
and not the sewage, and there is very little ground
for supposing that the micro-organisms of sewage,
in the absence of violent splashing, become disseminated
in the sewer air.
5. The sewer air contained 2 to 10 times as much
carbonic acid as the neighbouring fresh air (taken
at the same time), and no sulphuretted hydrogen gas
was found.
(b.) The experiments were made with an air shaft
erected at the Pimlico Pumping Station; an experimental
sewer (9-in., 80 feet long), laid in the Pump Room at
Pimlico Station ; and the Fulham Road sewer (400 yds.
long), close to the Town Hall, Fulham—a sewer containing
a large amount of heavy deposit, and being otherwise in a
most filthy condition and unventilated.
Conclusions drawn from Experiments.
1. Considerable increase in the velocity of the air current
does not produce an increase in the number of micoorganisms
found in the sewer air.
2. The conclusions obtained by experiment in a large sewer
(the King's Scholars' Pond sewer) hold good for a small
sewer (the experimental 9" sewer).
3. In an experimental sewer (9"), wherein the sewage was
allowed to remain stagnant for several weeks (the pipe
being filled to the extent of two-thirds of its sectional
area), the sewer air was found to contain very many
more micro-organisms (entirely moulds) than the air
outside; at least, in two out of the six experiments
made, a condition of things difficult of explanation,
4. In a filthy, unventila ed sewer (containing deposit), the