CHEMICAL EXAMINATION" OF THE WATER SUPPLY. 357 
Table 18. — Physical and chemical improvement in the water of tJie Potomac accom- 
plished by storage and sedimentation. 
[Compiled from analyses made in the division of chemistry of the Hygienic Laboratory, covering a period 
of 11 weeks, from July 16 to September 28, 1906.] 
Reservoir. 
Turbidity. 
Total solids. 
Chlorine. 
Ammonia. 
Nitrites. 
Nitrates. 
Disso 1 V e d 
oxygen. 
Per cent of 
saturation. 
Oxygen con- 
sumed. 
Free. 
Albumi- 
noid. 
Dalecarlia, inlet 
221 
203.0 
2.6 
0. 024 
0. 161 
0. 0031 
0. 61 
7. 44 
89.6 
4.1 
Washington City 
46 
141.0 
2. 47 
.017 
.096 
.0056 
.61 
7. 60 
90.4 
3.0 
Improvement in parts 
per million 
175 
62.0 
.13 
.007 
.065 
1. 1 
Improvement in per cent 
79 
30.5 
5.0 
29.0 
40.3 
27.0 
Table 19. — Physical and chemical improvement in the water of the Potomac accom- 
plished bv storage and sedimentation. 
[Compiled from analyses made in the laboratory of the filtration plant, covering a period of 20 weeks, 
from February 13 to June 26, 1906.] 
Reservmir. 
Tur- 
bidity. 
Sus- 
pended 
solids. 
Chlo- 
rine. 
Ammonia. 
Ni- 
trites. 
Ni- 
trates. 
Dis- 
solved 
oxygen 
Per 
cent of 
satura- 
tion. 
Free. 
Albu- 
minoid. 
Dalecarlia, inlet 
223.0 
31.0 
180 
2.0 
1.6 
0. 032 
.015 
0. 244 
.073 
0. 0033 
.0028 
0. 79 
.79 
Washington City 
9. 72 
94.4 
Improvement in parts 
per million 
192.0 
86.1 
.4 
20.0 
.017 
53.1 
.171 
70.0 
.0005 
15.0 
Improvement in per cent... 
1 
Table 20. — Chemical improvement of Potomac water as the result of filtration. 
Compiled from analyses made in the division of chemistry of the Hygienic Laboratory, covering a 
period of 11 weeks, from July 16 to September 28, 1906.] 
Reservoir. 
Turbidity. 
Total solids. 
Chlorine. 
Ammonia. 
Nitrites. 
Nitrates. 
Disso Ived 
oxygen. 
Per cent of 
saturation. 
Oxygen con- 
sumed. 
Free. 
Albumi- 
noid. 
Washington City 
46.3 
141.0 
2.47 
0. 017 
0. 096 
0. 0056 
0.61 
7. 60 
90.0 
3.0 
Storage basin 
46 
127.0 
2. 53 
.015 
.054 
.0003 
.67 
5.87 
71.4 
2.0 
Improvement in parts 
per million 
41.7 
14 0 
.002 
.042 
.0053 
1. 0 
Improvement in per cent 
90.0 
9.9 
11.8 
43.7 
94 6 
33.3 
