REPORT ON THE WORKING OF THE KING INSTITUTE, GUINDY
57
APPENDIX No. IX.
REPORT ON EXPERIMENTS WITH " STABILISED BLEACH " FOR THE
STERILIZATION OF DRINKING WATER.
Four samples of " Stabilised Bleach " made by Messrs. The United Alkali Co., Ltd.,
of England and supplied by Messrs. Parry & Co., Ltd., of Madras, at the instance of the
Director of Public Health, have been examined with reference to their keeping and sterilizing
properties. The results obtained with the four samples have been tabulated and appended
- hereto.
-
Sample " A" was supplied in a 5 lb. glass container, while the other three " B ", " C "
and " D " were supplied in zinc containers. From a careful study of the results obtained
the following conclusions appear to be justifiable :-
1. Bleaching powder when stabilised and stored in suitable receptacles, does not
show any appreciable loss of its active chlorine content even after 5 months.
2. Glass receptacles appear to be decidedly superior to metal containers for the
storage and issue of stabilised. bleach as the loss of available chlorine is more rapid when
stored in zinc containers than when stored in glass bottles.
3. Stabilised bleach is quite efficient for purposes of water sterilization.
Samples " C " and " D " which were received on the 21st of April 1923, were in all
probability drawn from the same stock as that from which sample " B " was supplied 5
months earlier. This is apparent from the fact that they contained only 13 . 5 and 14.6 per
cent respectively of available chlorine at the time of examination. These figures represent
approximately the residual chlorine content in sample " B " after the gradual loss of active
chlorine between November 1922 and April 1923. The zinc containers would be suitable in
cases where the contents are likely to be used up within a month of manufacture.
Experiments with stabilised bleaching powder manufactured by Messrs. The United.
Alkali Co., Ltd., Greenbank Works, Widnes, England, and supplied by Messrs. Parry & Co.,
Ltd., Madras.
Sample A in 5 lb. glass jar. Date of receipt, 16th November 1922.
Date of examination.
Strength of
the solution
used for test,.
Percentage of
available
chlorine.
Dosage of
chlorine for
Madras water
(Field test).
Result of bacteriological
examination.
16th November 1922
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20th
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23rd
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27th
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30th
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4th December 1922
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8th
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19th
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26th
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2nd January 1923
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16th
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18th
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22nd
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25th
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29th
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let February 1923
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19th
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22nd
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26th
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1st March 1923
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5th April 1923
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19th May 1923
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...
.„
...
,
PER CENT,
4
4
4
4
4
4
5
5
6
5
5
5
6
5
5
4
4
4
4
4
4
4
4
5
5
5
4
4
4
4
4
4
4
4
4
4
4
22'8
22'8
22'8
221
22'7
22'7
22'7
22'6
22'6
22'6
22'6
22'5
22'5
22'4
22'4
22'4
22.3
22'3
22'3
22'7
22.2
22'2
22'2
22'2
22'0
21'9
22'3
2] '9
22'0
21.8
21'8
21'6
21'7
21'b
21.5
21'5
21'5
PARTS PER
MILLION.
0•8
0'7
0'8
0.7
0.8
0.9
0.8
0'8
0•8
0'7
0'7
0'7
0'7
0.6
0.6
0.8
0.7
0'7
0 7
0.7
0.8
0.7
0.7
0'7
0.8
0'8
0'7
0 8
0 8
0.8
0.9
0.8
0'9
0.9
0.8
0'8
0 7
Not sterile.
Sterile.
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Do.
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• Do.
Do.
,