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THE FARMER'S MAGAZINE. 



power to furnish her longer with corn and manure, 

 then she will not be richer than before, in the means 

 of producing corn and meat, but will from time 

 forth become even poorer in these means." 



There is no gainsaying these remarks of the Ger- 

 man philosopher. Let us rather endeavour to stay 

 this outpouring of the riches of our soil. Let us 

 then inquire what hope there is for the future. 



One great difficulty in the utilisation of the 

 sewage is, in the case of London, about to be re- 

 moved ; its drainage has hitherto been pouring 

 into the Thames by a hundred different mouths — 

 these outpourings being commonly situated in 

 densely-popult.ted places, alike difficult to ap- 

 proach, either by chemical operations or by the 

 pump. The great intercepting sewers of the me- 

 tropolis now in the course of construction will 

 bring the excreta of between two and three mil- 

 lions of persons to two points — one on the north- 

 ern and the other on the southern side of the 

 Thames, and this at some distance from thickly- 

 populated neighbourhoods. The facilities thus af- 

 forded to the use of the pump (and I take it that, 

 in our present state of knowledge, the pump is the 

 only practicable agent) will be very considerable. 

 Either by public companies alone, or by the aid of 

 public grants or sanitary commissioners, this huge 

 mass of liquid manure will assuredly be rendered 

 available. 



Let us, then, once again endeavour to diffuse a 

 knowledge of what kind of substance we have to 

 deal with — its chemical composition — its amount — 

 the cost of pumping it from the level of the river 

 (where we find it) to such an elevation as will en- 

 able the farmer to lead it by its own gravity over 

 his grass lands. The chemical examination of the 

 excrements of a town population by Professor 

 Way is perhaps the best at present in our posses- 

 sion. He gives as the result of his examinations 

 {Jour. Roy. Ag. Sac, vol. xv. p. 140), that the 

 daily amount of matter contributed to the sewage 

 of a town by each individual (men, women, and 

 children) is | lb. of solid and 3 lbs. of liquid ex- 

 crement. The solid excrement contains about 75 

 parts in 100 of water. The dried solid matter 

 contained, in an analysis made in the Professor's 

 laboratory — 



100 



From the mean result of a series of experiments 

 on the urine or liquid portion of the excreta, it is 

 found that this contains about 30 parts in 1000 of 

 solid matter. This solid portion of evaporated 

 urine may be deemed to contain about the follow- 

 ing proportions per cent, of different fertilizing 

 substances : 



Organic matters and salts of ammonia 67.54 

 Insoluble sihcious matter . . . 0.09 



Oxide of iron 0.05 



Lime ....... 0.61 



Magnesia ...:.. 0.47 



Phosphoric acid 4.66 



Sulphuric acid 0.46 



Potash 1.83 



Chloride of potassium . . . .5.41 

 Common salt 18.88 



The quantity of sewage produced by a town has 

 been estimated by the bulk of the water used by 

 the inhabitants — data which it is needless to de- 

 scribe in this paper. From these we are safe in 

 assuming, with Professor Way, that the smallest 

 quantity of water which is at any time likely to 

 pass through the sewers of a town will be equal to 

 20 gallons per head of the population. It may be 

 more, but it cannot well be less. Twenty gallons 

 of water weigh 200 lbs. ; so that the solid and liquid 

 excrements of each person, containing altogether 

 only about 1,000 grains of solid matter, more than 

 half of which is soluble, are distributed through 

 200 lbs. (1,400,000 grains) of water. In other 

 words, the solid matter of the urine and fa?ces is 

 mixed with 1,400 times its weight of water. 

 " Here," truly enough adds the Professor, " is the 

 great difficulty of the subject." 



There are other sources than these, however, by 

 which the sewage of towns is enriched. In the 

 above calculation only about 50 grains of solid 

 matter might be expected to exist in an imperial 

 gallon of sewage; but the analysis of the flowing 

 contents of the London sewers shows a much 

 larger proportion of solid matter to exist in the 

 metropolitan sewage. In that of the sewers from 

 Barrett's Court {ib., p. 153) 492.26 grains per 

 gallon were present; in that from Dorset-square 

 209.70 grains. The solid matter from the Bar- 

 rett's Court sewage consisted of — 



Organic matter and salts of ammonia 301.82 

 Sand and detritus of the granite from 



the streets .... 20.69 



Soluble silica .... 12.51 



Phosphoric acid . . . 10.44 



Sulphuric acid . . . 14.73 



Carbonic acid . . . 15.59 



Lime ..... 24.53 



Magnesia .... 2.87 



Per-oxide of iron and alumina . 6.20 



Potash .... 14.13 



Soda ..... 1.51 



Common salt .... 33.24 



492.26 



Taking the estimate of Way as the basis of our 

 calculation, at least 40,000,000 gallons of this 

 hquid manure daily pours into the Thames, Such, 

 then, is about the average composition of the Lon- 

 don sewage, and such the enormous bulk of it which 

 will, before long, be collected at two places on the 

 Kent and Essex sides of the Thames. For those 

 great outlets to be rendered available for irrigation 

 it must be raised by the steam engine and the pump. 

 Two chief questions then arise — (1) the quantity of 

 sewage requisite for the irrigation of an acre of 



