15G 
Use of Town Sewage as Manwe. 
meclianics are in the houses, that the great bulk of fa?cal matter 
comes down. This is especially the case between eight and ten 
o'clock in the morning, at which time its collection is easily 
effected. I should observe in passing tluit the sewage of these 
towns on the pipe system is essentially different from that of 
London. The matters are in a very much more fresh and natural 
condition. A quantity of the solid matter was collected at the 
mouth of the Croydon sewer by means of a flannel bag ; it was 
allowed to drain as much as it would, and afterwards dried, with 
all the necessary precautions, for analysis. 
The following is the composition of the dry material : — 
Composition of Composition of 
the Asli. the Dry Matter. 
Organic matter 77*42 
Insoluble silieious matter . . . . 59'72 13'49 
Oxide of iron 8-62 1-95 
Lime 11-32 2-56 
Magnesia 3-04 0-69 
Phosphoric acid 12-11 2*73 
Sulphuric acid 1"12 2'25 
Potash None None 
Soda None None 
Chloride of ])otassiuni .... 2*79 0"63 
Chloride of sodium 1-28 0-28 
100-00 100-00 
Nitrogen 3 27 per cent. : equal to ammonia 3-94 per cent. 
I consider this material as the type of the best result that can 
be obtained by the mere mechanical filtration of sewage and the 
preservation of the solid product for manure. The change from 
the solid to the liquid state of the nitrogenous matters, of which 
mention has so often been made, has not yet occurred, and the 
substance may be taken to represent pure night-soil, washed, as 
it always will be, with abundance of water. But how stands the 
case? We have here a percentage of only 3 "27 nitrogen, equal 
to 3-94 per cent, of ammonia, on the absolutely dry product. 
This result is what we should have anticipated, and nearly 
accords with the analyses of washed excrements before given. 
That a more favourable result might sometimes be obtained, 
especially when the sewage of a rich population is operated on, 
there is every reason to believe ; l>ut, on the average, I feel cer- 
tain that better results are not likely to be got — that is to say, 
by mere mechanical filtration. But it seems to be acknowledged 
as a practical impossibility to fdter the sewage for the retention 
of the solid matter without the use of some material, such as 
charcoal, be adopted ; and, even supposing it were possible, some 
subsequent addition would be necessary to facilitate the economical 
drying of the product ; for to dry off the water from the faecal pulp 
