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is rich in sulphates and the latter in the products obtained from
the washings of the fumes from boiling tallow. The splitting up
of the sulphur compounds by the action of bacteria in the tanks at
the sewage works appears to bring about the production of
sulphuretted hydrogen, and the consequent annoyance of the
residents in the district.
Experiments have been carried out over many months by
adding chlorine in the form of" chloros" to the sewage. Chlorine
may act first of all by retarding the action of the bacteria producing
the sulphuretted hydrogen, out it may also act by splitting up the
sulphuretted hydrogen before it is liberated on the surface of the
sewage. Various proportions of chlorine have been added, but it
has been found that not less than fifteen parts per million is effective
in reducing smell. Half of that quantity does lessen the smell,
but fifteen parts gives a marked improvement of which there is
good evidence by the absence of complaints during the last months
of the year. It might be expected that the addition of such an
active antiseptic in such a quantity might act adversely on the
sewage purification process, which depends for its success on the
action of bacteria, but it has been found that the addition of this
quantity of chlorine has not adversely affected the character of
the effluent. Experiments were carried out by varying the point
of application of the chlorine, for example by adding half the
quantity at the point of entrance of the crude sewage into the
tanks and half at the point where the sewage passes from the tanks
to the filter beds, and by adding all of the chlorine as the sewage
is proceeding, after treatment in the tanks, to the filter beds, but
it was found beyond doubt that the best results were obtained by
adding the whole quantity of chlorine to the crude sewage as it
enters the works.
As this treatment will have to be continued, the best method
of adding chlorine will have to be evolved, but it seems the most
economical method is by adding chlorine gas, as is being done in
the treatment of the water in the swimming baths, where it has
been proved easy to work, very economical, and most efficient.
Closet Accommodation.—Except in the Greenford Ward
and the most northerly part of the Mount Park Ward the whole
of the houses are supplied with water closets, there being as a rule