II July, 1910.] 77/t' Purification of Muddy Waters. 



441 



into so much clean and attxiactive water, of good bacterial purity and 

 uncontaminated by any chemical. And this result was obtained by the 

 use of only half-a-pound of iron chloride without the need of any ex- 

 pensive plant, such as a large filter, or of any skilled labour. 



A second experiment proved an equal success, and a description illus- 

 trates a further practical detail. 



This time the tank was filled to its full capacity (850 gallons), and 

 i 11). of iron chloride in solution stirred into the water at the top (2nd 

 May, evening). Xext morning the water drawn off at the bottom still 

 showed a slight opalesence, and had not the perfect cleanliness and 

 brightness which it has when enough of the chemical is added. In con- 

 sequence, a further i-6th of a pound of dissolved chloride of iron was 

 added, and again the water allowed a night in which to clear. The fol- 

 lowing morning. 4th May, the water drawn off proved perfect. 



This experiment well illustrates how the addition of insufficient 

 chemical in the first place can be rectified by a further small addition 

 afterwards. In this way, just the right amount necessary is added, and 

 no waste occurs through adding too much. 



EXPERIMENTS WITH CHLORIDh Oi- IRON. 



Jars 10 inches diameter with vertical iron rod, and printed label behind. 



A. Pond water. Opaque and yellow brown. 



B. Same after treatment, 600 gals. -|- 5 lb. iron chloride. 



C. Yan Yean from tap in Melbourne. Far inferior in brightness and 

 cleanness to B. 



[a) Pond water (Mr. Ross, Deep Creek). Thick ^•ellow-red mud. 



{b) Same after treatment in open dnm (i lb. iron chloride per i,ooo gals.). 



It will be noted that in this experiment the precipitated mud had 

 settled through 7 feet of water during the night. The actual deposit of 

 mud was not more than half-an-inch in thickness. 



The bacterial count of the water before treatment was 22,000- 

 organisms per cubic centimetre. After treatment, the count was 240- 

 per c.c. 



