39 
BACTERIA IN WATER— 
1. Count number per 1,000 c. c. : 
a. In tap water. 
h. In river water. 
c. In spring water. 
d. In rain water. 
e. In ice. 
2. Varieties. 
3. Collecting samples. 
4. Estimation of organic matter — 
а. Free ammonia. 
б. Albuminoid ammonia. 
5. Estimation of nitrates and nitrites. 
6. Estimation of cblorids. 
7. Purification of water : 
Heat. 
Filters — 
а. Household filters. 
б. Field and camp filters, 
c. Sand filters — 
Alum. 
Hyperoxid of chlorin. 
Ozone. 
Permanganate of potash. 
