THE FARMER'S MAGAZINE. 



593 



entertained, if the olijcct be to manufacture a manure as a 

 commercial speculation. 



(b.J The magnesia process was not experimentally 

 examined : nevertheless, our researches into the nature of 

 sewage, together with the knowledge of the well-establiahed 

 chemical properties of the ammonio-magnesian phosphate, 

 especially of its solubility in water and other menstrua, 

 enable us to state that, owing to the extreme dilution of 

 the sewage, the addition to it of a magnesian salt would 

 produce either no precipitate of the ammonio-magnesian 

 phosphate at all, or only of a most minute quantity ; so 

 that the manure produced by this process would essen- 

 tially consist of the suspended matter of the sewage, wliich 

 might as easily be collected by simple subsidence, and 

 wliich contains only one-seventh of the valuable consti- 

 tuents of sewage. 



(c.) With reference to the 'two remaining processes, viz., 

 treatment with lime (A.), and agitation with charcoal (C. 2,) 

 we find from our experiments made on a small scale, that the 

 value of the manure produced considerably exceeds the cost 

 of the materials employed. However, on going minutely into 

 all the conditions involved in the manufacture of a manure 

 from the Loudon sewage by the two processes above men- 

 tioned, we come to the conclusion that they offer no chance as 

 commercial speculations. 



We have been led to this conclusion by considerations, among 

 which the following are the more important : — 



(1.) In estimating the commercial prospects of a process, it 

 is safer to rely upon the results obtained in a manufacturing 

 operation than on those furnished by experiments ou a smaller 

 scale. Now, analysis shows tbat the value of the article 

 manufactured at the works at Leicester, where the liming pro- 

 cess is adopted, is less than one-half of the value which experi- 

 ment assigns to our manure obtained ou a small scale. 



(2.) In calculating the probable expense of manufacturing 

 the sewage manure, the interest of the capital required for the 

 erection of works, the actual cost of producing, and the com- 

 mercial expenditure, we have but insufhcieut data, and they 

 have therefore probably been estimated below what would be 

 found to be the case in practice ; all these circumstances prove 

 that the profit resulting from the manufacture of sewage ma- 

 nure would be reduced to a very small amount. 



(S.) The nature of the manure manufactured by either of 

 these processes, its great bulk containing as it does but a very 

 small quantity of valuable constituents in a very large mass 

 of inert matter, increases the cost of carriage and spreading, 

 when compared with that of guano, to such an extent as to 

 limit its extent to a very small area. With reference to the 

 liming process, for instance, taking the value of the Leicester 

 bricks as representing the average value of the lime manure, 

 and starting from the calculation of the manufacturing expenses 

 chiefly furnished by the estimate of Mr. Wicksteed, the paten- 

 tee we hud that the profit ou a tou of lime manure sold at the 



works would be 5s. 3d., whiht at a distance of culy two ruilcs 

 from the works it could not realize more than 23. 3il. profit, 

 and when transported to a distance of five miles, the manure 

 would have to be sold at a loss. 



IV.— Utilization with Sewage in a Liauiu Statk, 



Irrigation with Sewage. 



In order fully to appreciate the proposal which has been 

 made of using sewage for the purpose of irrigation (an appli- 

 cation, the beneficial and advantageous results of which are 

 established beyond a doubt), it is necessary to recollect that 

 100 tons of London sewage contain 2i. 2|d. worth of valuable 

 constituents in the soUd, and 153. 4a-J. worth in the liquid 

 form ; and that in order to supply a meadow with valuable 

 matters corresponding in quantity to those contained in one 

 ton of guano, it is necessary to irrigate with 1,250 tons, or 

 310,000 gallons of sewage. 



A general consideration of the question points out the 

 great expense which necessarily must attend a regular distri- 

 bution in this way of the enormous quantities of sewage pro- 

 duced annually by the Metropolis ; nevertheless, there are too 

 many elements (engineering and agricultural) entering into 

 the question to enable us, as chemists, to pronounce any very 

 decided opinion as to whether the application of the sewage 

 of the Metropolis in this way would, or would not, be a re- 

 munerative commercial speculation ; but so far as we have 

 been enabled to ascertain, we believe that the proposal of 

 using it in this way is the one wMch appears to us to he the 

 most promising ; and, we would even say, the only tJiai lias any 

 chance of success as a commercial scheme ; and we would 

 therefore suggest that, in devising means for removing the 

 metropolitan sewage, they should not exclude the possibility 

 of giving this method the trial which it merits. 

 V. — Consideration op the Manufacture of Sewage 

 Manure from a Sanitary Point op Vieav. 



The several processes submitted to us for deodorizing and 

 consolidating sewage into a manure viz , (A.) by means of 

 lime — (B.) By the use of Stothert aud Gotto's mixture, 

 (C. 1,) by filtration through charcoal, and (C. 2.) by shaking 

 with charcoal — allfuljil, to a certain extent, the office for which 

 they were proposed. At the same time it is found that these 

 several processes leave a large quantity of putrescible organic 

 matter in solution, ivhieh, especially in hot weather, is apt to 

 undergo decomposition, and to give rise to the generation of 

 effluvia of the most offensive and dangerous character ; and we 

 believe that the erection of works in the immediate neighbour- 

 hood of the metropolis, {oi the deodorization of the Loudon 

 sewage, might prove very prejuiicial to the health and comfort 

 of the inhabitants of Loudju ; and that, in the event of the 

 establishment of such works the Jluid run off from the sewage 

 deposit, if discharged into the Thames in the vicinity of Lon~ 

 don, might very seriously affect the river. — Journal of the Society 

 of Arts. 



AUTUMN CULTIVATION. 



Sir, — If you think the following statement wortliy a 

 place in your valuable paper, it may perhaps show tlie 

 heav\--land farmers the advantage of following the plan ot 

 autumn cultivation adopted by Mr. ymith, of Woolstoii. 

 In an IG-acre field of heavy land I had one part sown last 

 autumn with tare?, not having seed enough. I left tlirce 



lands unsown, tliey were manured and ploughed the same 

 as the part so.vn ; the rest of tlie field was to be mangel 

 wurzel. In April, 1857, I went with olliers over Mr. 

 Smith's farm at Woolston. From what I saw of his culti- 

 vation 1 was convinced that if I sowed the above three 

 lands without plougliing the ground again I sliould liavc a 



