362 
EXCRETA OF TOWNS. 
by the use of charcoal, of which only one-fourth the quantity as compared to earth is 
required ; and, given a stock to commence with, by reburning the product the charcoal 
is obtained from the excreta itself. It is not necessary to re burn it after each use ; for 
dry closets it may be dried and used again five times before being reburned, and for 
urinals alone it may be used ten times. 
The reburning is conducted in apparatus which admits of collecting the ammonia, 
acetic acid, and tar which distil over in the usual condensers. The whole of the am¬ 
monia is thus collected, whilst the phosphoric acid, potash, and mineral matters accu¬ 
mulate in the charcoal, together with the carbon from the organic constituents of the 
excreta. The weight of the charcoal is increased to the extent of about 5 per cent, with 
each use, and if dried and re-used five times, about 25 per cent, with each reburning. 
With this constant addition, the char does not require replacing with fresh material; the 
ultimate result being that the excreta are absorbed and deodorized by a charcoal derived 
from themselves. Thus, a city working this process would, dn addition to securing the 
whole of the ammonia and other products of destructive distillation, become sellers of a 
charcoal second only in value to that from bones,—the product, in fact, of disintegrated 
bone and nyuscle. 
A city of 500,000 inhabitants, for instance, would produce 19 tons a day, or 6935 
tons a year ; the total quautity of excreta -to he removed being calculated at 385 tons 
a day, and its value at 29s. 6d. per ton—£569—the ultimate result -being the same. 
Any charcoal may be used at first, but that from seaweed is preferred as the best and 
cheapest. 
Attention is drawn to the fact that in such a population as that referred to, the fat 
passed in the solid excreta would amount to seven tons a day, and this would appear 
among the fatty oils of -the tar and form another of the products recovered. 
Starting with seaweed charcoal, a lengthened series of experiments with urine were 
undertaken, the results of which are tabulated. The same charcoal was used 100 times 
and reburnt 10 times, during which it had increased 183 per cent., and had given off 
ammonia equal to 316 per cent, of sulphate. The tables show the increase of potash, 
phosphoric acid, etc., for each reburning, .the phosphoric acid appearing as phosphate 
of lime; the charcoal, containing at first 20 per cent, carbonate of lime and 5 percent, 
phosphate, gradually decreases the carbonate to 2 per cent, and increases the phosphate 
to 25 per cent., at which it remains stationary, forming a sugar refiner’s charcoal. The 
phosphate of lime thus gradually deposited is equal to soluble phosphates for mammal 
purposes from its finely divided condition. 
The results of a series of experiments with a dry closet are also tabulated. The 
quantity of char used was only 48 oz., to which 18 oz. were added after, the total 
amount employed being 66 oz. ; the amount at,the .end of the experiment was 122 oz., 
57 oz. having been derived from the excreta. This small stock had served 181 uses and 
absorbed 808 oz. mixed excreta, having been dried and returned to the closet 17 times 
and reburnt 10 times. The analyses show this to be a prolific source of ammonia, the 
average yield of sulphate being f per cent, of the wet excreta and 31 per cent, of the 
dry. The yield of acetate of lime was 4 per cent, and of tar 9 per cent, of the dry 
excreta. A portion of the ammonia is combined with acetic acid. The char beeomes 
uniform at about 24 per cent, phosphate of lime, and 12 per cent, carbonate. This pro¬ 
cess then presents the following advantages,;— 
1st. Total freedom from all odour, even in an invalid’s room. 
2nd. Certain prevention of infectious diseases arising from sewer leakage into wells, 
or sewer gases into houses. 
3rd. Enormous saving of water and cost of closets. 
4th. It confines the nuisance instead of distributing it. One hundredweight of char¬ 
coal per month is sufficient for each closet, when used by six persons daily - and the 
whole may be allowed to fall at once from the closet through a 12-inch pipe to a 
cesspit below the house, and emptied once a year. The quantity is not more than the 
house ashes, 
5th. By this process only can the whole of the valuable material be recovered for the 
use of the land. -Instead of forcing on the fanner a large quantity of sewage when he 
does not want it, it enables us to store up .the manure in a convenient form until he re¬ 
quires it .and can pay its full value. 
