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53
Facing these difficulties, the Sanitary Department has adopted
a rule to the effect that such a test as the hydraulic test shall not
be applied to old drains as a routine, except with the written consent
of the owner. Consequently, the smoke or chemical test is
the one used by the Inspectors in their routine examinations of
drains of old houses in connection with house-to-house inspections,
visits to infected premises, etc. Unfortunately, the smoke
and chemical tests are not wholly satisfactory, and are only used
on the definite understanding that when a result is obtained from
such test we can be sure that the drains are defective, but where a
result is not obtained, we cannot state that the drains are, therefore,
all right or perfect. Considering all things, the chemical
test, as used as a routine in Lambeth, gives fairly satisfactory results,
though, of course, the water or hydraulic test is the only
thoroughly reliable one. I cannot, however, too strongly emphasise
that a negative result from the smoke or chemical test must
not be taken as meaning that the drains are satisfactory; as it is
a matter of experience that a negative result may be obtained
where the drains are known to be defective, which negative result
may be due to (1) varying states of the atmosphere; (2) condition
as to flow of the sewer into which the drain under examination
enters; (3) nature and depth of the soil in which the drain is
embedded, etc. Such was the case with the drain at No. 62,
I.eigham Vale.
I know of no Metropolitan or other Parish that employs, as a
routine, the water test in all cases, at least, in connection with
drains of old houses. The chemical tests at present in use in
Lambeth are Kingzetts' (No. 1) drain tests, made by the Sanitas
Company, and give off a very pungent odour when ignited.
Joseph Priestley.
May 14 th, 1900.
The Vestry decided to recommend that the following principle,
enunciated in another case, and affirmed, at its meeting held on
the 21 st July, 1898 (Minutes, page 1325), should be re-affirmed by
the Vestry, namely : —