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Other building materials examined included cements, asphalts, tiles, plywood
panels and synthetic materials, flooring of all types and floor sealers, hessian based
bituman sheeting for various purposes, material for expansion joints, cement waterproofers,
clinkers, mortars and concretes, rust removers, fireproofing and insulating
materials, etc. Many types of flooring were examined which varied considerably in
composition from coloured Portland cement to those mainly organic in nature,
such as polyvinyl chloride. In some cases, polyvinyl chloride plasticised with tricresyl
phosphate was filled with clay and asbestos and backed with hessian; magnesium
oxychloride is a usual constituent for some types with a variety of added components
such as wood dust, rubber powder and bitumen; various bitumen bound products
were examined. Important aspects of the examination of these products are their
resistance to staining and abrasion, fire resistance, water absorption and general
durability, as well as their thermal conductivity.
Woods were examined as to fungal or other attack and appropriate treatment
was recommended. The causes of structural failure were investigated as required
and the possible danger of sulphates to concrete was carefully watched, Samples of
clay and subsoil water were examined in many cases and the use of sulphate resisting
cement or high alumina cement advised where it was considered desirable.
Pablic Health
An important part of the work ot the Uhemical Branch irom the standpoint of
Public Health is that of ensuring the satisfactory quality of the drinking water used
in Council establishments. Where water is obtained from a mains supply no trouble
is experienced, provided care is taken to avoid contamination between the end of the
main and the service taps; but in a number of schools and institutions the supply is
drawn from private wells and, in these cases, continuous treatment and supervision
is given to ensure that the high standard appropriate to drinking water is maintained.
As a general principle, all such private supplies are chlorinated before use by means of
automatic dosing apparatus. The Chemical Branch carries out regular monthly
inspections and samples are taken of both the untreated and treated water for chemical
and bacteriological examination in the laboratory; chlorine tests are made on the
spot to confirm the adequacy of the dosage, which is also determined daily by the
resident engineer at each establishment.
Certain former L.C.C. hospitals have private wells and these have continued to
be included in the regular programme of water examinations at the request of the
Hospital Management Committees.
The air in the Council's vehicular tunnels under the River Thames was regularly
examined in order to ensure that the carbon monoxide content did not exceed the
safety limit; in view of the continued use of petrol containing lead compounds, the
lead content of the air was also checked occasionally and was found to be safe.
Considerable work was done during the year on atmospheric pollution, assays
being made by various methods of the polluting matter (total deposit, tarry matter,
sulphur gases, smoke, etc.) in the air at various places within the County and also,
for comparison, at two observation stations outside it. This work was done in conjunction
with a scheme sponsored by the Department of Scientific and Industrial
Research.
In accordance with an official arrangement, the Chemist-in-Chief accompanied
the Chief Alkali Inspector, Ministry of Housing and Local Government, on his
periodical visits to Battersea Power Station to test the efficiency of the flue gaswashing
process for the removal of sulphur compounds. At the close of the year only
70 per cent, of the flue gases were being washed at this station and no part of the
gas-washing plant at Fulham Power Station had been reconditioned and put into
operation.
Other fields of public health work which have been closely watched are those
dealing with insecticides and disinfectants and assistance and advice have been given
as required. The relation of the fluoride content of drinking water to the incidence of
dental caries has been kept under review. This is a matter which has been the subject