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8
presented to the Main Drainage Committee of the London
County Council:—
(a.) Sewer Air Investigations, I., by J. Parry Laws,
F.I.C. (May, 1892).
(b.) Sewer Air Investigations, II., by J. Parry Laws,
F.I.C. (December, 1893).
(c.) Investigations on the Micro-organisms of Sewage,
by Messrs. J. Parry Laws, F.I.C., and
Frederick W. Andrews, M.D. (December,
1894).
(a.) The experiments were made in the King's
Scholars' Pond Sewer, which runs from Piccadilly in the
north to Buckingham Palace Road in the south, and was
constructed 120 years ago.
Conclusions drawn from Experiments.
1. The micro-organisms in the sewer air are related to
the micro-organisms in the air outside, and not to
the micro-organisms of the sewage.
2. In the air both within and without the sewer, the
forms of micro-organisms present are almost exclusively
moulds and micrococci; on the contrary, the
micro-organisms of sewage are for the most part
bacilli.
3. That for purposes of deodorising, manganate of
soda + sulphuric acid, and carbolic acid are more
efficient than sulphurous acid or manganate of soda
alone, and, setting aside the question of relative
cost, the manganate of soda + sulphuric acid is
decidedly the best, the disagreeable smell of the
sewer air being removed completely thereby.
(N.B.— The sewage was deodorised in each case
for 24 hours previous to experiment.)