ANIMAL MANURES. 113 



That which is nearest the city brings the highest rent, chiefly 

 l)ecause it is near and more accessible to the point where the 

 grass is consumed, but also partly from the better natural 

 quality of the land. I'he average value of the land, irre- 

 spective of the sewer-water application, may be taken at £3 

 per imperial acre, and the average rent of the irrigated land 

 :it £30, making a difference of £27 ; but £2 may be de- 

 ducted as the cost of management, leaving £25 per acre of 

 clear annual income due to the sewer-water." 



162. The second plan proposed is to collect the sewage 

 matters in tanks, and, by the addition of slaked lime, made 

 into a cream with water, to throw down their most valuable 

 ingredients, and to collect and dry the deposit.* Though 

 by this method of treating the contents of sewers a solid and 

 portable manure is obtained which must possess considerable 

 fertilizing value, yet only a part of the ingredients of the 

 sewage is obtained, much of the Nitrogen present escapes in the 

 form of Ammonia, and a considerable amount of the soluble 

 inorganic or saline matters remain dissolved in the liquid 

 which is allowed to flow away after the removal of the deposit. 



163. What has just been stated of the valuable fertilizing 

 qualities of human excrements, and the importance which 

 is at present attached to their preservation in other countries, 

 may, I hope, induce you to give greater attention to these 

 manures. Night soil and urine may be readily converted into 

 manures, and their offensive odour removed, by very simple 

 means which should be known to eveiy farmer. Thus, by ad- 

 ding to them coal-ashes or saw-dust, moistened with a solu- 

 tion made by dissolving the substance called "green vitriol," 



* The following is the composition of a specimen of the deposit, pro- 

 cured from sewage, by the addition of cream of lime, Avhich, in the 

 course of some experiments, undertaken at the request of the Corpora- 

 tion of Belfast, I had occasion to analyze. 125 parts of the deposit, 

 dried at 212°, contained as follows: — 



Organic matters, capable of yielding 6.925 parts of ammom'a 81.25 



Phosphate of lime (bone earth) 10.46 



Sulphate of lime (gypsum) 2.00 



Carbonate of lime 19.63 



Lime 8.43 



Magnesia 1.23 



Alkaline chlorides 0.33 



Sand, &c 1.67 



126.00 



