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The following paragraphs give a general indication of the source of origin of
these samples and of the consultative and advisory duties carried out for the
various services and departments of the Council.
Due to progressive activity in the redecoration of premises a further considerable
increase occurred in the amount of work required on paints and allied surface
coatings. Many samples were also examined in connection with the revision of the
Council's approved list of paint manufacturers whose products may be tendered for
direct use by the Council or used by contractors on housing work, and for checking
the quality of those actually being applied on jobs in order to ensure that they were
up to standard. Many samples were reported upon adversely. Some special
materials were also submitted for examination such as (a) a preparation claimed to
be suitable for "cold galvanising": (b) a wall paint said to reduce fire risk:
(c) distempers which claimed special insecticidal properties as containing D.D.T.
A number of complaints of paint failure were inspected and samples taken for
subsequent examination in the laboratory. For example: (d) a failure was
ascribed to the use of lithopone as a constituent of an exterior paint: (e) another
paint failure was found to be due, not to the paint itself, but to the faulty preparation
of the wood surface before the application of the paint.
Other building materials examined included plasters, Portland and high
alumina cements, bricks, asphalts, road surfacings, clinkers, synthetic floorings,
mortars, granite, size, etc. Special matters which might be mentioned are: (f) the
possible danger of the effect of sulphates in ground water or clays on portland
cement concrete was watched and in some cases special precautions were recommended:
(g) two cases of failure of concrete with an aggregate containing brick
rubble were ascribed to incomplete wetting; the use of surface active agents was
advised to aid effective wetting: (h) jointless synthetic flooring materials were
examined on a systematic basis as to their use in kitchens: (i) black patches on a
newly papered wall were found to be due to a mould: (j) cases of suspected dry
rot were investigated.
The sewage from London north of the river Thames is treated at the Northern
Outfall Works, Beckton, by sedimentation, and about one-third of the flow, subsequently,
by the activated sludge process. That from London south of the Thames
is subjected at the Southern Outfall Works, Crossness, to sedimentation only. In
both cases most of the sedimented matter (sludge) is taken out into the estuary in
ships and dumped; the effluent is discharged into the river at the outfalls. Work
on the composting of sewage products with pulverised household refuse was continued
in 1949 and large quantities of such compost were made from sludge screenings.
The sludge digestion plant at the Northern Outfall Works dealt with a small
proportion of the sludge, and the sludge gas produced (containing about 70 per
cent. methane) was used for power production. The final effluents from the Outfall
Works are discharged into the river Thames and biochemical oxidation by the
dissolved oxygen in the water is the final process in their purification. The condition
of the water of the river is therefore of great importance and a careful watch was
kept upon it by regular weekly sampling and analysis at many points between
Teddington Weir and the sludge dumping area in the estuary.
The laboratories at the two outfall works carried out the chemical analyses
necessary for the control of the various plants during the year. Research work was
also done on several aspects of the sewage treatment problem and particularly in
reference to the dewatering of sludge by a new process involving freezing after the
addition of chemicals. A laboratory scale plant was operated on an experimental
basis and the Council authorised the filing of a complete specification for patents
both in this country and in the United States in the names of three officers of
the Chemical Branch (the Chemist-in-Chief, Mr. G. S. Clements and Dr. R. J.
Stephenson). Research also led to the adoption of a new method for the chemical
Housing
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drainage