310 



TALKS OX MANURES. 



and the phosphoric acid (soluble) worth 12 cents, a ton of such 

 urine would be worth, on the land, $4.06. 



"A ton of the fresh faeces," said the Deacon, "at the same esti- 

 mate, would be worth (20 Ibs. nitrogen, at 20 cents, $4; 21| Ibs. 

 phosphoric acid, at 12 cents, $2.70), $6.70." 



" Not by a good deal," said the Doctor. " The nitrogen and 

 phosphoric acid in the urine are both soluble, and would be imme- 

 diately available. But the nitrogen and phosphoric acid in the 

 faces would be mostly insoluble. We cannot estimate the nitrogen 

 in the faeces at over 15 cents a lb., and the phosphoric acid at 

 5 cents. This would make the value of a ton of fresh foeces, on tlie 

 land, $4.09." 



" This makes the ton of fasces worth about the same as a ton of 

 urine. But I would like to know," said the Deacon, " if you really 

 believe we could afford to pay $4 per ton for the stuff delivered on 

 the farm ? " 



" If we could get the genuine article," said the Doctor, "it would 

 be worth $4 a ton. But, as a rule, it is mixed with water, r.nd dirt, 

 and stones, and bricks, and rubbish of all kinds. Still, it is un- 

 questionably a valuable fertilizer." 



"In the dry-earth closets," said I, "such a large quantity of 

 earth has to be used to absorb the liquid, that the material, even if 

 used several times, is not worth carting any considerable distance. 

 Dr. Gilbert found that 5 tons of absolutely dry earth, before usinr, 

 contained 16.7 Ibs. of nitrogen. 



Af tei being used once, 5 tons of the dry earth contained 24.0 Ibs. 



" ' twice, " 3C.3 " 



three times,. " * * 44.6 " 



four times,.. " * ' 54.0 " 



five times, . . 

 six times,.... 



61.4 

 71.6 



Dr. Voelcker found that five tons of dry earth gained about 7 Ibs. 

 of nitrogen, and 11 Ibs. of phosphoric acid, each time it was used 

 in the closets. If we consider each lb. of nitrogen with the phos- 

 phoric acid worth 20 cents a lb., 5 tons of the dry earth, after being 

 used once, would be worth $1.46, or less than 30 cents a ton, and 

 after it had been used six times, five tons of the material would be 

 worth $11.98, or about $2.40 per ton. 



In this calculation I have not reckoned in the value of the nitro- 

 gen the soil contained before using. Soil, on a farm, is cheap. 



It is clear from these facts that any earth-closet manure a farmer 

 would be likely to purchase in the city has not a very high value. 

 It is absurd to talk of making " guano " or any concentrated fertil- 

 izer out of the material from earth-closets. 



