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. 



Siniilar tanks can be dug in other drains about the 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 fer 100,000, 



Total i!>olids 42.000 



Chlorine 1 5. 000 



Free Ammonia ... 0.040 



Albuminoid Ammonia O.I 50 



Nitrates and Nitrites 2.000 



Nitrites Present 



I certify that this water is so polluted as to be unfit for human 

 cncsumption. 



