Use of Town Sewage as Manure. 
143 
Human urine varies in composition with every alteration in 
the age and health. It would be next to impossible to give any 
analysis to represent fairly the urine of a mixed population. 
I liave presented in a note below * the mean result of a con- 
siderable number of examinations of this fluid, by which we are 
led to the conclusion that 1000 parts of urine contain usually 
about 30 parts of solid matter, half of which quantity consists of 
urea and uric acid, whicli are substances containing nitrogen — 
the other half being tolerably evenly divided between fixed or 
mineral salts, such as alkaline and earthy phosphates, sulphates, 
and muriates, and organic compounds destitute of nitrogen.t 
Urea and uric acid are substances containing very large quan- 
tities of nitrogen, which by their spontaneous decomposition 
produce ammonia. Urea contains nearly 50 per cent, and uric 
acid about 33 per cent, of nitrogen. These substances constitute 
the chief but not the only value of human urine as a manure. 
Phosphate of lime and alkaline phosphates are also important 
* According to Becquerel, the composition of urine, taking the mean of males 
and females, is in round numbers, in 1000 parts — 
Water 
Solid constituents 29^ parts 
Urea . . . • , 
Uric acid 
Fixed salts .... 
Organic salts . 
1000 • 
+ The following is an analysis of the solid matter of evaporated urine, the 
sample being prepared from the mixed urine of several individuals voided at 
difte»ent times : — 
Composition of 
tlie Ash. 
Composition of 
the Dry Urine. 
Organic Matters and Salts of Ammonia . 
67 
54 
0 
28 
0 
09 
0 
14 
0 
05 
1 
89 
0 
61 
1 
49 
0 
47 
14 
31 
4 
66 
1 
43 
0 
46 
5 
64 
1 
83 
None. 
None. 
16 
65 
5 
41 
58 
17 
18 
88 
100 
00 
100 
00 
Per Cent. 
Nitrogen 19-43 
Equal to Ammonia 23-60 
970^ 
13^ 
H 
