396 G. J. BURROWS. 



of free ammonia, the total ammonia showing only a slight 

 reduction, except in Ex. I, with lime, which showed a con- 

 siderable reduction from *071 to '039. This was possibly 

 owing to the slow filtration, one and a half hours being 

 consumed. In each of the other cases the time taken was 

 about half an hour. The total hardness was not affected to 

 any extent. 



Second Sample of Water.— Another sample of water was 

 collected on February 7th, 1909. This was very turbid, 

 being collected after heavy rains. 



Hardness — Temporary ... 4 parts per 100,000 

 „ Permanent ... L6 ,, ,, 



Total 20 



In this estimation the heavy sediment was allowed to 

 settle and the still turbid water then poured out. 



Experiments on Clarification.— The agents tried were 

 lime, alumino-ferric, ferrous sulphate, and mixtures of these. 

 200 cc. stoppered measuring cylinders 10^ inches in height 

 were used for these experiments. Large quantities (*5 

 grams to 200 cc.) of the three clarified the water very 

 quickly. Smaller quantities (*1 gram) of each indicated 

 that alumino-ferric was the best agent ; this quantity of 

 alumino-ferric clarified the water in a few minutes, whereas 

 the same quantity of the other two (lime and ferrous 

 sulphate) required several hours. Mixtures of the three 

 reagents were also tried, but these were inferior to the 

 alumino-ferric alone. 



Using quantities of alumino-ferric and slaked lime, con- 

 taining approximately the same weight of element ('0054 

 grams) i.e., *01 gram Ca(OH) 2 to 200 cc. of water and '0342 

 grams alumino-ferric to 200 cc. of water, it was found that 

 the cylinder containing the alumino-ferric settled in eight 

 minutes, the other did not settle in six hours but was fairly 



