London Labour and the London Poor, volume 2
Of the Qualities, Etc., of the Sewage.
THE question of the value, the uses, and the best means of collecting for use, the great mass of the sewage of the metropolis, seems to have become complicated by the statements which have been of late years put forth by rival projectors and rival companies. In our smaller country towns, the neighbourhood of many being remarkable for fertility and for a green beauty of meadow-land and pasturage, the refuse of the towns, whether sewage or cesspoolage (if not washed into a
|current, stream, or river), is purchased by the farmers, and carted by them to spread upon the land.|
By , I mean the contents of the , or of the series of sewers; which neither at present nor, I believe, at any former period, has been applied to any useful or profitable purpose by the metropolitan authorities. The readiest mode to get rid of it, without any care about ultimate consequences, has always been resorted to, and that mode has been to convey it into the Thames, and leave the rest to the current of the stream. But the Thames has its ebbs as well as its flow, and the consequence is the sewage is got rid of.
The most eminent of our engineers have agreed that it is a very important consideration how this sewage should be not only innocuously but profitably disposed of; and if not profitably, in an immediate money return, to those who may be considered its owners (the municipal authorities of the kingdom), at least profitably in a national point of view, by its use in the restoration or enrichment of the fertility of the soil, and the consequent increase of the food of man and beast.
Sir George Staunton has pronounced some of the tea-growing parts of China to be as blooming as an English nobleman's flower-garden. Every jot of manure, human ordure, and all else, is minutely collected, even by the poorest.
I have already given a popular account of the composition of the metropolitan sewage, &c. (under the head of Wet Refuse), and I now give its scientific analysis.
In some districts the sewage is more or less liquid —in what proportion has not been ascertained— and I give, in the place, an analysis of the sewage of the King's Scholars' Pond Sewer, , the result having been laid before a Committee of the . As the contents of the great majority of sewers be the same, because resulting from the same natural or universally domestic causes (as in the refuse of cookery, washing, surface-water, &c.), the analysis of the sewage of the King's Scholars' Pond Sewer may be accepted as of sewer-matter generally.
Evidence was given before the committee as to the proportion of "land-drainage " to what was really , in the matter derived from the sewer in question. A produce of grains of manure was derived from a gallon of sewer-water. Messrs. Brande and Cooper, the analyzers, also state that gallon ( lbs.?) of the liquid portion of the sewage, evaporated to dryness, gave . grains of solid matter, . grains of which was again soluble, and contained—
This insoluble portion consisted of
The deposit from another gallon weighed grains, of which . were combustible, being composed of animal matter "rich in nitrogen," some vegetable matter, and a quantity of fat. Of this matter . grains consisted of
Other Reports and other evidence show that what is described as "earthy matter and sand" is the mac, mud, and the mortar or concrete used in pavement, washed from the surface of the streets into the sewers by heavy rains; otherwise for the most part the proper load of the scavager's cart.
Further analyses might be adduced, but with merely such variation in the result as is inevitable from the state of the weather when the sewage is drawn forth for examination; whether the day on which this is done happens to be dry or wet.
It has been ascertained, but the exact proportion is not, and perhaps cannot be, given, that the extent of covered to uncovered surface in the district drained by the King's Scholars' Pond Sewer was as to , while that of the Ranelagh Sewer, not far distant, was as to , at the time of the inquiry ().
Mr. Smith, of Deanston, stated in evidence, that the average quantity of rain falling into King's Scholars' Pond Sewer was cubic feet in a year, and he assumes tons as the amount of average minimum quantity of drainage (yearly), yielding cwt. of solid matter in each tons = in .
Dr. Granville said, on the same inquiry, that he should be sorry to receive on his land tons of diluted sewer water (such as that from the uncovered Ranelagh Sewer) for ton of really fertilizing sewage, such as that to be derived from the King's Scholars' Pond Sewer.
I could easily multiply these analyses, and give further parliamentary or official statements, but, as the results are the same, I will merely give some extracts from the evidence of Dr. Arthur Hassall, as to the microscopic constituents of sewage-water:—
"How do you account," the Doctor was asked, "for the comparative absence of animal life in the water of most sewers?" "It is, doubtless, to be attributed," he replied, "in a great measure, to the large quantity of sulphuretted hydrogen contained in sewer-water, and which is continually being evolved by the decomposing substances included in it."
"Have you any evidence to show that sewerwater does contain sulphuretted hydrogen in such large quantity as to be prejudicial and even fatal to animal life?" "With a view of determining this question, I made the following experiments:—A given quantity of Thames water, known to contain living infusoria, was added to an equal quantity of sewer-water; examined a few minutes afterwards, the animalculæ were found to be either dead or deprived of locomotive power and in a dying state. A small fish, placed in a wine glass of sewer-water, immediately gave signs of distress, and, after struggling violently, floated on its side, and would have perished in a few seconds, had it not been removed and placed in fresh water. A bird placed in a glass bell-jar, into which the gas evolved by the sewer-water was allowed to pass, after struggling a good deal, and showing other symptoms of the action of the gas, suddenly fell on its side, and, although immediately removed into fresh air, was found to be dead. These experiments were made, in the instance, with the sewer water of the sewer (near the Blackfriarsroad); they were afterwards repeated with the water of other sewers on the Middlesex side, and with the same result, as respects the animalculæ and fish, but not the bird; this, although evidently much affected by the noxious emanations of the sewer-water, yet survived the experiment."
"Would you infer from these experiments that sewer-water, as contained in the Thames near to London, is prejudicial to health?" "I would, most decidedly; and regard the Thames in the neighbourhood of the metropolis as nothing less than diluted sewer-water."
"In what way do you suppose these various vegetable cells, the husks of wheat, &c., reach the sewers?" "They doubtless proceed from the fæcal matter contained in sewage, and not in general from the ordinary refuse of the kitchen, which usually finds its way into the dust-bin."
"Sewer-water, then, although containing but few forms of animal life, yet contains, in large quantities, the food upon which most animalculæ feed?" "Yes; and it is this circumstance which explains the vast abundance of infusorial life in the water of the Thames within a few miles of London."
The same gentleman (a fellow of the Linnæan Society, and the author of "A History of the British Fresh-water Algæ," or water-weeds considered popularly), in answer to the following inquiries in connection with this subject, also said:—
"What species is most abundant in the Thames from Kew Bridge to Woolwich?" "The of Ehrenberg; this occurs in all seasons of the year, and in all conditions of the river, in vast and incalculable numbers; so much so, that a quart bottle of Thames water, obtained in any condition of the tide, is sure to be found, on examination with the microscope, to contain these creatures in great quantity."
"Do you find that the infusorium of which you have spoken varies in number in the different parts of the river between Kew Bridge and Woolwich?" "I find that it is most abundant in the neighbourhood of the bridges." [Where the outlet of the sewers is common.]
"You find then, in Thames water, about the bridges, things decidedly connected with the , as vegetable and animal matter in a state of decomposition?" "I do; about the bridges, and in the neighbourhood of London, there is very little living vegetable matter on which animalculæ could live; the only source of supply which they have is , and which is to be regarded as the food of these creatures. Where infusoria abound, under circumstances connected with sewage, vegetable matter in a living condition is certain to be met with."
Respecting the , I may add the following brief observations. Without wishing in any way to prejudice the question (indeed the reader will bear in mind that I have all along spoken reprovingly of the waste of sewage), I am
|bound to say that the opinions I heard during my inquiry from gentlemen scientifically and, in some instances, practically familiar with the subject, concurred in the conclusion that the of the metropolis cannot, with all the applications of scientific skill and apparatus, be made either sufficiently portable or efficacious for the purposes of manure to assure a proper pecuniary return. In this matter, perhaps, speculators have not traced a sufficient distinction between the liquid manure of the sewers and the "," or dry manure, manufactured from the more solid excrementitious matter of the cesspools, not only in Paris, but, until lately, even in London, where the business was chiefly in the hands of Frenchmen. The staple of the French "" is that is, the outpourings of the sewers—for this is carried into the Seine, and washed away with little inconvenience, as the tide hardly affects that river in Paris; but it is altogether "," that is, the deposit of the cesspools, collected in fixed and moveable utensils, regulated by the "universal" police of Paris, and conveyed by Government labourers to the Voiráes, which are huge reservoirs of nightsoil at Montfauçon, about miles, and in the Forest of Bondy, about miles, from the centre of Paris. The London-made manure also was all of cesspoolage; the contents of the nightman's cart being "shot" in the manufacturer's yard; and when so manufactured was, I believe, without exception, sent to the sugar-growing colonies, the farmers in the provinces pronouncing it "too hot" for the ground. The same complaint, I may observe, has been made of the French manufactured cesspool manure. I heard, on the other hand, opinions from scientific and practical gentlemen, that the sewer-water of London was so diluted, it was not profitably serviceable for the irrigation of land. All, however, agreed that the sewage of the metropolis ought not to be wasted, as it was certain that perseverance in experiment (and perhaps a large outlay) were certain to make sewage of value.|
The following results, which the Board of Health have just issued in a Report, containing "Minutes of Information attested on the Application of Sewer-water and Town Manures to Agricultural Production," supply the latest information on this subject. The Report says , that "to be told that the average yield of a county is bushels of wheat per acre, or that the average weight of the turnip crop is tons per acre, means very little, and there is little to be learned from such intelligence; but if it is shown that a certain farm under the usual mode of culture yielded certain weights per acre, and that the same land, by improved applications of the same manure, by the use of machinery, and by , is made to yield the weight of crop and of than was previously obtained, a lesson is set before us worth learning."
It then proceeds to cite the following statements, on the authority of the Hon. Dudley For- tescue, as to the efficiency of sewage-water as a liquid manure applied to land.
"The farm we visited was that of Craigentinney, situated about mile and a half south-east of Edinburgh, of which Scotch acres" (a Scotch acre is - more than any English acre) "receive a considerable proportion of such sewerage as, under an imperfect system of house-drainage, is at present derived from half the city. The meadows of which it chiefly consists have been put under irrigation at various times, the most recent addition being nearly acres laid out in the course of last year and the year previous, which, lying above the level of the rest, are irrigated by means of a steam-engine. The meadows laid out are watered by contour channels following the inequalities of the ground, after the fashion commonly adopted in Devonshire; but in the more recent parts the ground is disposed in 'panes' of half an acre, served by their respective feeders, a plan which, though somewhat more expensive at the outset, is found preferable in practice. The whole acres take about days to irrigate; the men charged with the duty of shifting the water from pane to another give to each plot about hours' irrigation at a time; and the engine serves its acres in days, working day and night, and employing man at the engine and another to shift the water. The produce of the meadows is sold by auction on the ground, 'rouped,' as it is termed, to the cowfeeders of Edinburgh, the purchaser cutting and carrying off all he can during the course of the letting, which extends from about the middle of April to October, when the meadows are shut up, but the irrigation is continued through the winter. The lettings average somewhat over the acre; the highest last year having brought , and the lowest ; these last were of very limited extent, on land recently denuded in laying out the ground, and consequently much below its natural level of productiveness. There are cuttings in the year, and the collective weight of grass cut in parts was stated at the extraordinary amount of tons the imperial acre. The only cost of maintaining these meadows, except those to which the water is pumped by the engine, consists in the employment of hands to turn on and off the water, and in the expense of clearing out the channels, which was contracted for last year at , and the value of the refuse obtained was considered fully equal to that sum, being applied in manuring parts of the land for a crop of turnips, which with only this dressing in addition to irrigation with the sewage-water presented the most luxuriant. appearance. The crop, from present indications, was estimated at from to tons the acre, and was expected to realize the ton sold on the land. From calculations made on the spot we estimated the produce of the meadows during the months of cutting at the keep of cows per acre, exclusive of the distillery refuse they consume in addition, at a cost of to per head per week. The sea-meadows present a particularly striking example of the
|effects of the irrigation; these, comprising between and acres skirting the shores between Leith and Musselburgh, were laid down in at a cost of about ; the land consisted formerly of a bare sandy tract, yielding almost absolutely nothing; it is now covered with luxuriant vegetation extending close down to highwater mark, and lets at an average of per acre at least. From the above statement it will be seen how enormously profitable has been the application in this case of town refuse in the liquid form; and I have no hesitation in stating that, great as its advantages have been, they might be extended or fold by greater dilution of the fluid. or times the extent of land might, I believe, be brought into equally productive cultivation under an improved system of drainage in the city, and a more abundant use of water. Besides these Craigentinney meadows, there are others on this and on the west side of Edinburgh, which we did not visit, similarly laid out, and I believe realizing still larger profits, from their closer proximity to the town, and their lying within the toll-gates."|
Such, then, are said to be the results of a practical application of sewer-water. The preliminary remark of the Board of Health, however, applies somewhat to the statement above given; for we are not told what the produced before the liquid manure was applied; nor are we informed as to the peculiar condition and quantity of the land near Craigentinney, and how it differs from the land near London.
The other returns are of liquid manures, of which sewer-water formed no part, and, therefore, require no special notice of them. The following observations are, however, worthy of attention:—
 The following is the analysis of a gallon of sewage, also dried to evaporation, by Professor Miller:— Ammonia . . . . . . 3.26 Phosphoric acid . . . . . 0.44 Potash . . . . . . . 1.02 Silica . . . . . . . 0.54 Lime . . . . . . . 7.54 Magnesia . . . . . . 1.87 Common salt . . . . . . 13.66 Sulphuric acid . . . . . 7.04 Carbonic acid . . . . . 4.41 Combustible matter, containing 0.34 nitrogen . . . . . . 5.80 Traces of oxide of iron. ------ Making in solution . . . . 45.58 ------ Matters in suspension, consisting of combustible matters, sand, lime, and oxide of iron . . . 44.50
 The following note appears in Mr. Fortescue's statement:—"In some trial works near the metropolis sewer water was applied to land, on the condition that the value of half the extra crop should be taken as payment. The dressings were only single dressings. The officer making the valuation reported, that there was at the least one sack of wheat and one load of straw per acre extra from its application on one breadth of land; in another, full one quarter of wheat more, and one load of straw extra per acre. The reports of the effects of sewer-water in increasing the yield of oats as well as of wheat were equally good. It is stated by Captain Vetch that in South America irrigation is used with great advantage for wheat."