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sewage were cool, and the latter much diluted by rainfall. But
their addition, it was stated, purified and deodorised the effluent
to such an extent as to render its discharge into the river
unobjectionable at all states of the tide, a statement very
generally traversed. I mentioned also that the Board, in order
to prevent nuisance within the Metropolis, arising from the discharge
of offensive gases from the sewer ventilators, were
applying the manganate and the acid, at numerous stations, to
the sewage as it flowed through the main sewers. It was hoped
that this plan would ensure the arrival of the sewage at the
outfalls in a deodorized condition, and thus assist in the production
of a satisfactory effluent. The object of the Board was
to avoid the necessity for costly land filtration of the effluent, as
recommended by the Royal Commission on Metropolitan Sewage
Discharge, with a view to ensure the removal of all odour and
the possibility of " secondary fermentation." The Board, in giving
effect to the views of their scientific advisers, incurred a large
expenditure for works of construction, and in the carrying out
of the system adopted.
SIR HENRY ROSCOE'S REPORTS.
Deferring, however, to the objections made to the system
above described, the Board, in 1887, retained the services of Sir
Henry Roscoe, F.R.S., as consulting chemist and scientific
adviser, to report on the question of the deodorisation of the sewage
at the Outfalls, and they ultimately consented to the request
of certain sanitary authorities—your Vestry among the number—
to make that gentleman's reports public. The reports were five
in number. The first, dated 16th May, 1887, dealt with "The
Deodorization of Sewage in the Metropolitan Sewers;" the second
and third, dated August 7th and December 9th, 1887, with
"The Deodorization of Sewage at the Outfalls." The fourth
report, dated March 3rd, 1888, treated of the deodorization of
sewer emanations by the use of sulphurous acid applied at
numerous stations within the Metropolitan area; while the fifth