THE FARMER'S MAGAZINE. 



89 



The first mode has the advantage of commonly 

 requiring less outlay of capital than is essential to 

 construct sewers sufficient to convey the sewage to 

 the necessary distance from densely inhabited dis- 

 tricts. But then it has the almost insurmounta- 

 ble disadvantage, that the solid manure thus pro- 

 duced by the deodorizing works is of too little value 

 to be worthy of the farmer's attention, more espe- 

 cially in such places where the richer refuse matters 

 of towns are largely obtainable at a very reasona- 

 ble rate. It is most desirable that we should well 

 understand this portion of the inquiry. It has been 

 successfully examined by Mr. R. S. Burn, (Qtcar. 

 Jour. Arjri. 1S58, pp. 270-386.) He gives the esti- 

 mate of Messrs. Hoffman and Witt, who have cal- 

 culated the agricultural value of the soluble and 

 insoluble constituents of 100 tons of London 

 sewage. It is as follows ; — 



Soluble. Insoluble. 



s. d. s. d. 



In its original state .. .. 15 4.V 2 3j 



(Total value 17s. 8d.) 



After treatment with lime .. 11 11 — 



After filtration through charcoal 11 IJ- — 



After shaking with charcoal .. 10 11 J — ■ 

 After treating with Stothart and 



Gotta's mixtures 12 5 — 



From these numbers, as it is truly observed by 

 these chemists, it is obvious that six-sevenths of 

 all the fertilizing constituents of sewage are in 

 the soluble form ; and that, in the liquid which re- 

 sults from the deodorizing processes by means of 

 lime and charcoal, a very considerable proportion 

 of the soluble agents of the original sewage remain 

 unremoved. 



We are furnished, however, with the means of 

 still further and practically examining this branch 

 of the inquiry. Professor Voelcker analyzed the 

 solid sewage manure, which is skilfixlly precipitated 

 at Leicester by means of lime, moulded into the 

 form of bricks, and properly dried, for the greater 

 convenience of carriage. In lOD parts of these 

 bricks were contained : 



Water 10.52 



Organic matter 12.46 



Insoluble siliceous matter .. 13.50 



Sulphate of lime 1 .76 



Oxides of iron, and alumina. . 2.89 



Carbonate of lime 52.99 



Carbonate of magnesia 3.67 



Common salt 0.45 



Potash 0.26 



Phosphate of lime 2.27 



Nitrogen 0.60 per cent. 



Ammonia 0.72 „ 



From this analysis, the value of the Leicester 

 sewage brick manure is 15s. 5d. per ton; but, as- 

 suming it to be 18s., then, as it takes 12^ tons of 

 these bricks to give the same amount of fertilizing 



matter as 1 ton of guano, these chemists have thus 

 shown the relative cost of applying the bricks and 

 guano as a manure : 



AT THE FACTORY. 



Guano. 



£ 



1 ton guano 11 



Spreading o 



£11 9 

 Leicester Brick. 



£ s. d. 



12^ tons ir 



Spreading 9 9 



£11 9 9 



AT A DISTANCE OF KIVE MILES. 



Guano. 



£ s. d, 



1 ton of guano 11 



Carriage 5 



Spreading 







£11 



Leicester Brick. 



12i tons 



Carriage 3 



Spreading 



£ s. d. 



110 



2 6 



9 9 



£14 12 3 



It is evident, therefore, that in general the 

 sewage brick manure of Leicester best bears an 

 economical comparison witb guano at the manu. 

 factory, which is the place where it is most exposed 

 to competition v/ith more concentrated organic 

 town manures. It would seem, therefore, that the 

 further the deodorizing works are removed from 

 ])opulous places, the more valuable is the sohd 

 manure produced; the farmer, in distant places, 

 commonly becoming more willing to purchase 

 heavier and less-concentrated fertjilizers, if obtain- 

 able near his land. 



Where we have the power to apply sewage in its 

 original state to grass-land, we get rid of all the 

 labour of deodorization, and utihze the most fer- 

 tilizing (or liquid) portion of the sewage. Here, 

 however, we have to apply it in large proportions : 

 it is idle to expect very considerable benefits from 

 the limited amount which is very often used. The 

 liquid employed can only possess fertilizing powers 

 from (first) its water, or (second) the foreign 

 matters chemically or mechanically diffused 

 through it. Now, to give to an acre of grass-land 

 the fertilizing power of 4 cwt. of guano, it is neces- 

 sary to use 250 tons of sewage; but then, in so 

 doing, we apply water equal to a depth of 2^ 

 inches of rain. 



My readers will remark that the results of these 



H 2 



