202 Value of Earth-Closet Manure. 
An elaborate inquiry, made some years ago by Mr. J. B. 
Lawes, into the composition of the excrements of a large mixed 
population, gave him results which he calculated as follows : — 
Table showing the estimated coustituents of Human Exceeta. 
Ounces per head 
per day. 
Average of both 
sexes 
and all ages. 
Pounds per head 
per annum. 
Average of both 
sexes 
and all ages. 
2-01 
45-95 
•45 
10-34 
•74 
16-85 
•35 
7-94 
•42 
9-64 
•20 
4-58 
The average amount of dry substance voided in the excre- 
ments of each individual of the population in twenty-four hours, 
it will be seen by these figures, is only two ounces ; or equal to 
about 46 lbs. per annum. The two ounces of dry substance 
contain rather less than half an ounce of mineral matters, or about 
10 lbs. per head per annum. About two-fifths of the mineral mat- 
ters, or one-tenth of the total dry substance, consists of phosphates. 
Of the valuable constituent, nitrogen, there is an average of 
rather more than one-third of an ounce per day, or about 8 lbs. 
per annum ; and these amounts of nitrogen are equal to '45 of an 
.ounce per day, or nearly 10 lbs. per annum of ammonia. 
Mr. Lawes's estimate of the amount of dry matter in the excreta 
of a mixed population of both sexes and all ages differs but 
little from the preceding calculations, which are based on some 
direct experiments by Professor Way. 
According to Mr. Lawes's estimate the money-value of the 
excreta per head per annum will be 8s. lOrf., allowing ^ 
s. d. 
10 lbs. of ammonia at 9f/. per lb. 7 6 
4.i ,, ol phosphates 2c;. per lb 0 9 
Other iiiatlers 0 7 
8 10 . 
Bearing in mind that five-sixths of the total amount of 
ammonia in the solid and liquid excreta of man are furnished by 
the utine, and only one-sixth by the faeces, and how small "is the 
proportion of the total urine that is passed at the same time, and 
that our domestic habits prevent the collection and absori)tion of 
