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51
These figures are very similar to those of last year, though the number of feeding
stuffs showing a deficiency on the guarantee is slightly less. One sample supplied
as "ground phosphates" was found to consist of basic slag, which has a much lower
phosphoric acid content. A "meat meal" was adversely reported on as containing
an excessive amount of vegetable husks, seed, etc. A sample of Turkish middlings
was found to contain an appreciable quantity of corncockle seed and condemned as
being likely to be harmful if fed to poultry.
There is still much evidence of a lack of appreciation of the meaning of the
statutory statement, which frequently bears little relation to the composition of the
material. This is usually rather better than the statement suggests.
A careful watch has been kept during the year on the quality of the drinking
water at those institutions of the Council which derive their supplies from private
wells. Two hundred and ninety-six samples have been examined from thirty-seven
institutions. As a result of the advice given on the basis of these analyses, permanent
chlorinating plants have been installed during the year at four wells (London
industrial colony, Sutton; Hanwell mental hospital; St. Pancras institution; and
West Park mental hospital). In the case of the other three large institutions in
which chlorinating plants had previously been installed, these have functioned
satisfactorily during the year. An improvised chlorinating system was also fitted
up at Hanwell residential school, the expense of a permanent plant not being considered
justifiable in view of the pending closure of the school. Directions were also
supplied to a tenant of the valuer's department as to chlorinating the supply from
a well on his rural premises. Temporary chlorination of tanks was again carried out
early in the year at Mitcham children's home, which was closed soon afterwards.
In two other large institutions, as a result of the analyses of samples of water, recommendations
were made for a thorough cleaning out of the storage tanks; after this
treatment the quality of the water was satisfactory.
In addition to the sampling and examination of fuels for the tramways and other
departments, and the routine chemical examinations necessary for the maintenance
of adequate control in the water system of the power station and in the combustion
of the various fuels employed, the work of the Greenwich laboratory during the year
has included the investigation of a number of problems connected with the installation
and operation of high-pressure plant having sufficient capacity to carry the bulk
of the peak load of the station, coal economy and corrosion.
The introduction of this plant, involving higher temperatures and pressures has
necessitated a much more critical adjustment of furnace and boiler condition than
heretofore.
The regular examination of the sewage treated at the outfalls and of the effluent
and sludge produced has been carried on since the present treatment was begun
in 1888 and 1890 respectively. At the southern outfall the percentage of dry matter
in the sludge was 7.8 per cent., the corresponding figure for the northern outfall
being 8.75 per cent.
The dry matter in individual cargoes varied from 1 to 16 per cent. at the southern
outfall, the mode lying between 7 and 8 per cent. The corresponding figures for the
northern outfall varied between 4 and 15 per cent., the mode being about 9 per cent.
The examination of the water of the Thames near the outfalls, begun in 1885,
and more extended examinations in the course of the sludge ships and at a few places
above the outfalls have been continued. The condition of the upper reaches of the
tideway has been investigated. This work is of increasing importance owing to
the changing activities of riverside undertakings, which may conceivably alter the
character of the water of the river which flows through the county, and also is the
diluting medium for the council's effluent. The weather conditions during the
summer were such as to make it unnecessary to treat the effluent from the Council's
outfalls works.
Experiments are being conducted at Crossness on the anaerobic digestion of
sludge. The plant is designed to allow of agitation and of digestion at varying
temperatures. The gas evolved can be measured and its calorific value determined.
Water
supplyPrivate
we
Greenwich
power
station.
Outfalls.
River
Thames.
Sludge
digestion.