CHEMICAL EXAMINATION OF THE MATEE SUPPLY. 359 
Table 24. — Composition of tap water as compared with the water of Dalecarlia reservoir 
inlet and the water of the storage basin. 
Water. 
Total resi- 
due. 
Mineral mat- 
ter. 
Volatile 
matter. 
Chlorine. 
Ammonia. 
Nitrates. 
1) i s s o Ivcd 
oxygen. 
Per cent of 
saturation. 
Oxygen con- 
sumed. 
o 
u 
Albumi- 
noid. 
Nitrites. 
Dalecarlia reservoir, inlet « 
203 
156 
47.1 
2.6 - 
0. 024 
0. 161 
0. 0031 
0. 61 
7.44 
89.6 
4.1 
Storage basin, filtered b 
127 
88 
39 
2.53 
.015 
.054 
. 0003 
.67 
5.87 
71.4 
2.0 
Tap or hydrant c 
123 
75 
48 
2.69 
.011 
.031 
. 00007 
.03 
6. 20 
81.39 
1.83 
oAverage of 14 analyses covering a period of 9 weeks from July 31 to Sept. 27, 1906. 
, 6 Average of 14 analyses covering a period of 9 weeks from July 31 to Sept. 27, 1906. 
/ cAverage of 49 analyses covering a period of 11 weeks from July 16 to Sept. 28, 1906- 
Table 25. — Averages of chemical analyses of tap water for different periods during July, 
August, and September of 1906. 
Period covered by the ex- 
amination. 
Total solids. 
Chlorine. 
Ammonia. 
Nitrites. 
Nitrates. 
Dissolved oxygen. 
Percent of satura- 
tion. 
Oxygen consmned. 
Mineral mat- 
ter. 
Volatile mat- 
ter. 
Free. 
i 
Albuminoid. 
July 16 to 20, inclusive (av- 
erage of 11 analyses) 
123. 1 
73.7 
49. 4 
2. 41 
0. 0136 
0. 0371 
0. 00015 
0. 62 
7. 06 
86.77 1 2.15 
July 23 to 27, inclusive (av- 
erage of 15 analyses) 
126.3 
68.4 
57. 9 
2. 54 
.010 
.0389 
. 00004 
.664 
6.36 
78. 00 2. 24 
Julv 31 to Aug. 6, inclusive 
(average of 18 analyses) . . 
117. 4 
75. 8 
41. 6 
2. 97 
.0136 
.023 
. 00006 
.596 
5.80 
71. 61 1. 57 
Sept. 28, (average of 5 
analyses! 
132. 4 
92. 6 
39. 8 
2. 74 
.001 
. 0185 
Trace. 
. 68 
.... .80 
July 16 to Sept. 28, inclu- 
! 
sive (average of 49analy- 
1 
ses) 
122.9 
74.9 
48 
2.69 
.0111 
.0308 
. 00007 
.63 
6.2 
81.39 i 1.83 
i 
; Table 26. — Comparison of analyses of tap water for summer period of 1904^ and 1906. 
f ■ [Compiled from data given in ‘ The Potomac River Basin,” Water-Supply Paper No. 192, United States 
’ Geological Survey, by Horatio M. Parker, 1904, and analyses made in the Hygienic Laboratory, divi- 
sion of chemistry.] 
Source of data. 
Period. 
Total solids. 
Chlorine. 
Ammonia. 
Nitrites. 
Nitrates. 
Required oxygen. 
Total residue. 
Mineral mat- 
ter. 
Volatile mat- 
ter. 
Free. 
c 
a 
3 
Data contained in bulle- 
June 3-Sept. 28, 
184 
144 
40 
46 
0. 037 
0. 28 
0. 0026 
0.39 
1. 79 
tin of Geological Survey 
1904 
(average of 10 analyses) . 
Hygienic Laboratory, di- 
July 16-Sept. 28, 
123 
75 
48 
2. 69 
.011 
.031 
.00007 
.63 
1. 83 
vision of chemistry (av- 
1906. 
erage of 49 analyses) . 
a Before the filter plant went into operation. 
