View report page

48
that whilst the water content of coke immediately after quenching or after storing
in the open may be even higher than 20 per cent., the natural moisture of this
material is of the order of 1 per cent. Coke stored under cover should not contain
much more than this small amount.
Vitamins in It was found that although the proportion of fat-soluble vitamin in butter and
ranrjjanno. simj]ar fats is too small for the now well-known colour test wTith dehydrating agents
to give definite indications, the separation of the unsaponifiable matter of such fats
furnished a suitable means of concentrating the vitamin. Comparative tests with
various margarines showed that a sample said to contain irradiated ergosterol gave
marked indications with the colour test, whereas ordinary vegetable margarine gave
no indication.
Th'ame The systematic examination of the river Thames was continued during 1927,
at points from Waterloo Bridge to the Edinburgh lightship. The daily examination
of the rivei water showed that the heavy rainfall and great fresh-water flow during
the year had the effect of keeping the proportion of salt water in the river much
lower during the latter half of the year than in 1926. Notwithstanding this, the
condition of the river as to dissolved oxygen was much the same as in 1926, until
October, when an appreciable improvement was observed in the reaches towards
the middle of the county.
Outfalls At the outfall laboratories, systematic daily examinations of the sewage, reac hing
the outfalls and the resulting effluent and sludge as well as of the water of the river
Thames at both high and low tides have been continued. The systematic analyses
of samples in connection with the working of the outfalls have also been made at
these laboratories in addition to the research work undertaken in connection with
activated sludge.
Biological ^ During the year, research on this subject has been continued. Another system
sewage60 °f mechanical agitation different from that which had given very satisfactory results
has been investigated and found to be less suitable for the Council's purposes. The
phenomenon known as " bulking " has occurred, and is being investigated in order
to discover, if possible, the cause and means of restoring bulked activated sludge
the properties of rapid sedimentation and nitrifying power which it has lost. The
difficulties arising from " bulking " have from time to time been experienced wherever
" activated sludge " treatment has been adopted, and although it presents no difficulties
which cannot by proper means readily be overcome, its investigation promises
improved methods of dealing with the problem based on definite knowledge of the
controlling circumstances. Investigation has also been started into the digestion
of sludge and the resulting combustible gases evolved in this process.
Greenwich The routine chemical examination of samples in connection with water softening,
station boiler waters, and condenser leakages at the power station has been continued
throughout the year. A large number of testings of coal used at the power station
and at other depots of the Council has been made, as well as of a considerable number
of paints for iron work at the station. An investigation of the deterioration of turbine
oils under continued use was carried out in part here, and in part at the central
laboratory. Other matters connected with the working of large turbo-generators
have been investigated.
Bathing At the request of the Parks Committee an exhaustive investigation was under-
open-air1 taken, during the bathing season, of the waters and deposits in various baths in
swimming the Council's parks and open spaces. Special attention was given to two baths which
baths. had been fitted with filtering plant and a similar bath not so fitted.
The deterioration of water in a bath begins as soon as the bath is used. However
clean the bathers may be, each contributes somewhat to the contamination of the
water. This effect is cumulative unless, indeed, the volume of water is so great relative
to the number of bathers that natural purification will always go on as rapidly as
contamination. This could never happen in an artificial bath used to a reasonable