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164
purity of the river. There was in the water more oxygen and
less chlorine—evidence of a better condition of the water. Sir
Henry Roscoe reiterates the opinion expressed in his former
reports, "that the use of chemicals of any kind must be considered
as a temporary measure," and that" any reasonable
outlay on them will not prevent a foul condition of the
river," in a dry summer or during hot weather. He is not
responsible for the scheme of the Board for chemical precipitation.
If this can be advantageously adopted, and the sludge be
carried to sea, he still thinks" that the sewage, whether
previously clarified or not,, must either be filtered through land
(as recommended by the Royal Commission) or discharged into
the estuary at a point not higher than the Sea Reach."
The Chemical Examination of the Foreshores and
Mud Deposits of the River Thames and its Estuary, forms
the subject of a further and final report by Sir Henry Roscoe,
dated March 4th, 1889, and is the outcome of a resolution by
the Board, approving of the recommendation of Sir Henry
Roscoe, "that an examination should be made of the condition
of the Thames deposits from Barking down the river to the
mouth, including the whcle of the estuary." It appeared
desirable, in view of the proposal to carry the sludge out to sea,
and of questions which may arise thereon, to be in possession
of scientific data as to the condition of the foreshores. The
examination was of a twofold character, chemical and microscopical,
the latter part being conducted by Mr. Dibdin, the
Chemist to the Board. The mud was collected at points where, in
consequence of the sot of the tides, sewage-sludge would, in the
Engineer's opinion, be most likely deposited on the foreshores
and banks; and from Clacton, Walton-on the-Naze, and
H arwich, as positions which, in the judgment of competent
persons, were those where sewage-sludge would be found if it
were discharged at sea, and should it then reach the shore.
The investigation was made in September and October last.
The samples divide themselves into two classes : (1) those