Appx. XXI.

Specimens for laboratory examination.
should be allowed to rúm to waste freely, so that impurities
in the pipe lumen may be washed out before a sample is
taken.

     (b) Bacteriological samples.— The following additional precautions
are necessary:—

     (i) If sampling from a tap, flame the tap for a minute and
then let the water run to waste f or three minutes before
taking the sample.

     (ii) Before opening the sterilised bottle, flame its neck and
stopper by means of a spirit lamp. With a similarly
sterilized pair of forceps, remove the stopper and hold
it thus until, after a final passage through the flame,
it is replaced in the bottle, which should meanwhile
have been completely filled so that no bubble of air is
finally retained.

     (iii) Pack the bottles in a box with ice and saw-dust, or with
dry saw-dust if no ice is obtainable.

     4. Transmission, of samples and particulars.— To enable it to be
identified each sample should be securely labelled, giving full parti-
culars regarding its source.

     Samples will always be forwarded by the most expeditious route.
Those for bacteriological examination should reach the laboratory
within 48 hours of collection. Except in cases of emergency they
should not arrive on a Saturday or Sunday.

     Full particulars embodying information on the following points
     must be despatched at the same time as, but separately from, the
     samples:—

(i)The reasons for, and the exact nature of, the examination
required.

(ii) Date and hour of sampling.

(iii) Nature and location of source of water, ánd site of sampling.

(iv) Nature and distance of any source whence an inflow of
pollution appears probable.

(v) Geological strata (as far as readily ascertainable) likely to
affect the water constituents.

(vi) If the source be a well, depth to water, depth of water
steining, coping, covering, strata penetrated, method of
raising water.

(vii) If a stored surface-water—nature of collecting surface and
conditions of storage.

(viii)Meteorological conditions, with reference to recent drought
or heavy rainfall.

(ix) Any treatment the water has received which may alter its
constituents, e.g., clarification, chlorination, softening or
boiling.

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