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collected on the foreshores of the river proper, from Barking
and Crossness down to Southend on the north, and Jenkin
Sands on the south; (2) those on the estuary, from Shoeburyness
to Harwich on the north, and from Warden Point to Margate
on the south, including two sandbanks known as "Little
Sunk" and "Gunfleet." The Royal Commission of 1884
stated a conclusion "that foul mud, partly composed of sewage,
accumulates at Erith and elsewhere," a conclusion borne out
by the well-known appearance of black patches of offensive
matter in the river, derived from sewage-sludge, which are at
times raised to the surface, as a result of putrefaction and the
evolution of gases, which, becoming entangled with the
material, cause it to float. Analyses of 59 samples of the mud
and deposits collected from the foreshore of "sections of the river
of considerable length" were made, the average composition of
which indicates that a gradual diminution occurs in the impurity
of such deposits from the outfalls downwards. The river for
the purpose of the inquiry was divided into four sections, viz. :—
(1) Halfway Reach to Erith Roads inclusive ; (2) Long Reach
to Gravesend Reach ; (3) Ovens Flat to Blyth Sand ; (4)
Chapman Lighthouse to Southend inclusive. The reliability of
four different means adopted for ascertaining the existence of
sewage impurity in the deposits is considered in detail. The
conclusion obtained from a comparison of all the numbers given
in the tables, taken together, is stated to be of distinct value for
obtaining a general view of the relative chemical condition of
the foreshores ; and a Table has been constructed to show the
average relative amount of the organic impurity in the various
sections of the river (and of the estuary). Taking the total
values or average impurity of Section 1 as 100, that of Section
2 is 90, that of Section 3 is 49, that of Section 4 is 16—there
being a total percentage loss of impurity in passing from the
Outfalls to Southend of 84 per cent. The presence of manganese
in samples taken in Section 1, and in that Section only, is cited
as a further proof that Sewage imputities exist in the river deposits—the
manganese being derived from the manganate of soda