Lecture on Town Sewage: Delivered at the Weekly Council Meeting of the Royal Agricultural Society, May 28, 1862 (Google eBook)

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W. Clowes and Sons, 1862 - Sewage - 11 pages
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Page 4 - I find an average of nearly 70 grains ; sometimes a little less, sometimes a little more. We must naturally expect such variations. Dr. Wrightson also found there about 70 grains ; and in the sewage of other towns the average of solid matter is seldom much higher than 80 or 90 grains. Even in the most concentrated sewage of Birmingham the amount of solid matter is, as I know, seldom higher than 105 grains. On the whole, then, I believe we are not far wrong in stating that town sewage contains on...
Page 7 - Ibe. of insoluble phosphate, worth Is.; thus we arrive at 13s. 6d. as the calculated value of a ton of farm-yard manure. I need not say that this calculated value is far above that which we actually pay. 3s. per ton, or at the most 5s. per ton, is, I believe, the price generally given for farm-yard manure. Making the same calculations for fresh farm-yard manure, I find the following result. We have 6$ Ibs.
Page 4 - ... character of the solid matter. Messrs. Hoffman and Witt estimated that the 102 grains which, according to them, are found in the imperial gallon, consist of nitrogen 6-7 ; phosphoric acid, 1/8 ; potash, 1 ; organic matter, 30-7 ; or a total quantity of 40'2 grains of fertilising matter the remaining 62 grains being worthless. Supposing a gallon of London sewage to contain 90 grains of solid matter an over-estimate, which 1 take that I may be certain of dealing fairly with sewage ...
Page 8 - ... ordinary farm produce ; but I believe that this is a mistake, and that in nutritive quality the grass from the irrigated meadow will be found inferior to that from natural pastures, the produce of meadows irrigated by sewage being in a still higher degree inferior. In fact, the more rapidly produce is grown the less mature it is, and the more likely to produce disorders in the animal economy ; whilst, bulk for bulk, the poorer the meadow the more scanty the herbage, and the more slowly it grows,...
Page 3 - ... 25 were made altogether, but I reject one, because it contained an enormously large quantity of solid matter taking 24 normal analyses of Dr. Letheby, and grouping them into two classes, the one showing less and the other more than 86 grains, I find in the former class 15 analyses furnishing on an average only 66 grains of solid matter in the imperial gallon, and in the other nine samples yielding on an average 123 grains. Now, considering that this occasional excess of solid matter takes...
Page 7 - Ibs. of insoluble phosphate of lime, 8^d. ; 12jlbs. of potash, 3s. lid. ; and 15 Ibs. of ammonia, 7s. 6d. ; or a total of 13s. We thus get a value for rotten manure of 6d. less per ton than for fresh ; and in both cases assume the value of farm-yard manure to be two or three times as high as it is in reality. Now, in dealing with a manure still more bulky, still less under our control than farm-yard manure, I cannot see why we are not to take into consideration that its value in a great measure depends...
Page 5 - ... service for such an object. When once the roots are fairly established, with their various fibres drawing nourishment from the soil, and their leaves spread to the sun and air, and thus the apparatus for taking in food on all sides is formed, the natural sources of supply are amply sufficient to provide for their luxuriant growth. We cannot, in fact, materially alter the composition of our soils, taking the whole bulk of the soil into consideration, by any amount of manure. Nor can we, chemically...
Page 5 - Ibs. of salts of ammonia, 2 of mineral matter, and in this mineral matter half an ounce of phosphoric acid, 1 of potash, and nearly 2 Ibs. of worthless matter. A ton of the dry constituents of sewage contains 163i Ibs.
Page 5 - The amount of phosphate of lime is calculated at 71. a ton, and the potash at 31/. a ton ; the result being that the total solid residue from sewage is thus valued, in round numbers, at 6?. per ton. Now, following the same track which other chemists have trodden, I find that, by taking the average composition which I here assume, the solid matter in London sewage would be worth about 5?. 2s.
Page 5 - This point deserves special attention, fur in valuations of the sewage of towns it is always compared with Peruvian guano. Now, if we leave the water out of consideration, it is hardly fair to compare the dry matter of the sewage with a material like guano, which hardly contains any valueless substance. Let us now examine the value put upon sewage by various chemists. Professor Hoffman calculates that a ton of sewage is worth on an average about 2d., or 17s. Id. per 100 tons. Accordingly the whole...

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