4542-1906-Reports-on-the-Health-and-Sanitary-Condition-of-the-Colony-of-Hongkong-for-the-year-1905 — Page 133

748 THE HONGKONG GOVERNMENT GAZETTE, MAY 11, 1906.

2. Among the chemico-legal investigations conducted during the year were 18 cases of suspected human poisoning, in six of which opium was detected. In another case the poison found was prussic acid.

WATERS.

3. The results of the analyses of samples taken each month from the Pokfulum and Tytam Reservoirs, from the Kowloon service, and Cheung Sha Wan supply, indicate that these supplies continue to maintain their excellent qualities. From time to time waters from places in China have been sent for examination. When- ever such have been proved to be unwholesome, a recommendation has been made (when no good source has been available), that the polluted water should not be used for potable purposes until after boiling, and in time of epidemic should be rendered still more safe by conversion after boiling into lemon water. For doubt- ful water another purifier has recently been receiving attention. This agent is copper, a minute quantity of which has been shown by several observers to be efficacious in destroying cholera and typhoid bacilli in water. At the same time the quantity of copper used is so small as to be quite tasteless and in no way dele- terious to the system. KRAEMER, writing in the "Chemical News" of August 4th, 1905, states that to obtain sterilised water he places a strip of clean sheet copper, nine inches square in three to four quarts of water and allows it to remain from four to eight hours, and then pours off the water. He mentions that such coppered water has been consumed by himself and by several families for more than six months with no injurious effect whatever. KRAEMER'S paper also mentious that when copper foil is allowed to remain in distilled water from one to five minutes, it has been shown that sufficient copper is dissolved to kill typhoid organisms within two hours. Some experiments have been made in this laboratory so as to whether this simple process can be recommended to those who by stress of circumstance or situation are in doubt about their water supply.

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The following results expressed in grains per gallon, were obtained with water of various qualities using sheet copper in the proportion of 80 square inches to one gallon :---

Distilled water after five minutes' treatment was found to contain th of a

100

grain of copper. Four waters of undoubted purity after four hours' treatment each contained th of a grain, and after 20 hours th of a grain of copper. Two bad waters contained th and th of a grain, respectively, after eight hours and 4th and th of a grain after 24 hours. It will therefore be seen that if copper be used in the proportion above stated, and allowed to remain in any water from four to eight hours, there is no fear of the presence of a poisonous amount of copper. The copper sheet must be bought from a European house as pure c pper. Chinese yellow metal should not be used.

Copper should be very useful in this Colony for vegetables. KRAEMER places the lettuce, celery, or other vegetables to be eaten raw, in a vessel of water con- taining a strip of copper, for two to four hours with occasional agitation.

A good deal has been written by many observers on the effect of copper on man, and those interested should read the paper mentioned above, but it may be said that it has been shown conclusively, that no ill effects have been noticed or are likely to be noticed from the consumption of water or vegetables treated as directed by copper.

A personal use of such water for about a fortnight was un- dertaken to see whether there were any effects that might be worthy of notice. But the treated and untreatel water were indistinguishable in taste, appearance, and palatability, and in all other essential properties.

4. Enquiries have been made as to the suitability for boiler purposes of certain waters in the Colony. Such waters although extremely soft contain a small quan- tity of silica, and it was desirable to ascertain what effect, if any, was produced on iron. Generally speaking, it may be said that all fresh water here, other than some well-waters, are very suitable for boilers.

In one particular boiler, filtered Tytam water had been use for more than 10 years, and so little had the iron of the boiler been affectel, that in some places it had retained its original bloom.

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