10. The filter is a Patterson pressure filter said to contain sand and charcoal. This filter is steamed once a week to sterilize the filtering material.
11. The chlorinating apparatus is a Patterson Chloronome one of the most reliable on the market. The dose of chlorine is stated to be 0.6 parts per 1,000,000. A dose of 0.25 is generally considered sufficient for filtered water.
12. Under the conditions of working the filter can only be regarded as à strainer and cannot be relied on to prevent the passage of bacteria. The safety factor lies in the amount of chlorine used. If there be a sufficiency all organisms will be killed but if there be an insufficiency some will escape.
13. For years samples of this water have been submitted to the Government Bacteriologist for examination. As a rule the results have shown the samples to be of a high standard of purity but occasionally a sample has not been up to the mark. During the investigation in connection with the epidemic special attention was paid to the water supply and samples were submitted for examination both to the Government Bacteriologist and the Government Analyst. The reports from both these authorities were satisfactory.
Flies.
14. With regard to flies there can be no doubt that at times the farm depot is heavily infested with these insects. The Pasteurisation plant, the cooling plant and the bottling plant are in what is usually described as fly proof rooms but flies do find entrance and do settle sometimes on the cleaned cooling plant and on
on the cleaned and sterilised bottles and on the bottling machine. The company place the blame for the flies on the Pokfulam village on the opposite side of the road a collec- tion of huts or small houses occupied by pig keepers and market gardeners. From time to time for the last sixteen years this village has been proved to breed flies. The Sanitary Department on the other hand have proved that the manure pits of the Dairy Farm itself are fruitful breeding places for flies. Action is being taken by the Sanitary Department to bring about an abatement of the nuisance.
Carriers.
15. Specimens from the stools of all employees engaged in the handling of milk were submitted to the Government Bacteriologist for examination to discover if any of the workers were dysentery carriers. Altogether specimens from 113 employees were examined. These included 7 foremen cowmen, 60 milkers, 4 bottlers, 4 engaged in separating, cooling or pasteurising, 9 can washers, 13 distributors, 8 ice cream workers, and 8 others.
16. The results of the stool examination showed none positive for dysentery bacilli of the Shiga type but eight positive for dysentery bacilli of the Flexner type. In five cases the organisms isolated though they gave positive sugar tests were not agglutinated by sera containing homologous agglutinins. None of the individuals from whom the specimens were taken showed any signs or symptoms of disease or had any history of recent illness.
17. Of the agglutinable positives one specimen came from a milker and two from ice cream workers. Of the non-agglutinable positives two came from milkers, two from bottlers and one from an ice cream worker.
18. Those who had given positive results were immediately taken off their ordinary duties and their places taken by others whose stools had given negative results.
19. On a subsequent examination made a fortnight later seven of those who had given a positive result proved negative. One who formerly had been engaged in bottling and who had non-agglutinable organisms in his stool was still positive for such organisms. He however showed negative on a third examination.