489 
The cost of these would be about 4s. 2d. or say $4 on the estate. 
There should be wooden doors across the drain above and below 
the first and last settling tank, which could be closed if necessary 
after rain to keep the tanks full. 
The lime water should then be sprayed Over the tank, followed by 
the alum solution, the water being stirred to cause even admixture. 
Finally the permanganate solution can be sprayed on as uni- 
formly as possible after the bulk of the precipitate has settled. 
If the pink colour produced by the last salt disappears rapidly, 
more permanganate should be added until the water remains pink 
for at least half an hour. 
The water will then settle clear and practically free from odour 
and can be pumped to the factory from the nearest tank. 
The drain between the settling tanks can be the same depth as 
the tanks so that all the water can be uniformly treated. 
Similar tanks can be dug in other drains about tlie estate to 
provide clear water for tapping and washing purposes. 
For drinking purposes the water can be boiled in addition, but if 
the right amount of permanganate is added it is not absolutely 
necessary. 
The quantity of Lime added should be sufficient to neutralise 
the acidity and can be increased with impunity as a hard water will 
probably be found to give better results in the factory. 
I thought perhaps you would like to publish this regarding 
brackish water for the benefit of estates on the ordinary Selangor 
alluvial soils. 
Water from Lapan Utan Rubber Co., Ltd. 
Parts per 100,000, 
Total Solids ... ... 42.000 
Chlorine 15.000 
Free Ammonia 0.040 
Albuminoid Ammonia 0.150 
Nitrates and Nitrites 2.000 
Nitrites Present 
I certify that this water is so polluted as to be unfit for human 
cncsumption. 
