ANALYSIS OF POKFULAM WATER.
Results expressed in grains per gallon.
Total solid matter dried at 212° F., Chlorine,
Free ammonia,
Albuminoid ammonia,
Oxygen absorbed in 4 hours at 80° F.,
Hardness (Wanklyn's scale),
i. Collected on the 5th June, 1889.
REMARKS.
ii. Same as i, after treatment with alum and subsequent filtration. * Of this quantity only 3.9 grains were in actual solution.
17th June, 1889.
i.
ii.
* 19.6
2.8
*42
*42
None.
None.
⚫0098
⚫0042
⚫065 1.3
⚫032
1.0
351
W. EDWARD CROW,
Apothecary and Analyst.
THE SANITARY BOARD AND THE ALUM PROCESS.
CIVIL HOSPITAL,
27th May, 1889.
SIR,-In reply to your letter No. 172 of the 25th instant, I have the honour to transmit the enclosed Memorandum on the alum process for clarifying water.
If these directions are translated into Chinese I would recommend that the parts underlined in red ink, which would not be understood by the native population, be omitted.
The Secretary,
SANITARY BOARD.
I have &c.,
W. EDWARD CROW,
Apothecary and Analyst.
DIRECTIONS FOR TREATING DRINKING WATER WITH ALUM.
Into an ordinary Chinese water bucket put about 20 grains of alum, in coarse powder or as much as can be easily placed on a one-cent piece. Add a small quantity of water and stir until the alum is completely dissolved then fill the bucket with water.
Or, prepare a standard solution of alum by dissolving half an ounce of the salt in sufficient water to fill an ordinary wine bottle and use a sherry-glassful of the solution for every bucket of water.
On a large scale the water may be clarified by dissolving a 4 or 3rd of an ounce of alum in as much mater as will fill an ordinary Shanghai bath-tub.
With this proportion of alum the water will become clear in twelve or eighteen hours; if, however, a supply is required in a shorter time, use double the quantity of alum.
The vessel should be rinsed out each time with fresh water before refilling and treating as above. Water from the mains treated in this way should be used for domestic purposes in preference to water from any of the wells in the city of Victoria.
Hongkong, 27th May, 1889.
W. EDWARD Crow.