196 
Value of Earth-Closet Manure. 
In estimating the money value of the earth-closet manure 
it is but lair to deduct from the value of the compost that of 
the earth used in its production. Taking for a basis of calcu- 
lation the composition of the perfectly dry earth, and the three 
samples of closet-manures produced in the West Riding Prison, 
we have more specially to consider the relative proportions of 
phosphoric acid and of nitrogen in the four samples. 
In the drv earth before use I found 'IS per cent, of phosphoric 
acid, and "31 per cent, of nitrogen. Once used in the closet 
the earth compost was found to contain only '07 per cent, more 
phosphoric acid, and 06 per cent, more nitrogen than it did 
before. These differences are quite trifling, and it may be said 
with perfect justice, that the earth, after having been used once, 
is not more valuable for manuring purposes than in its original 
dry and sifted condition. 
On comparing the amount of phosphoric acid and nitrogen in 
the earth passed twice through the closet, we find an increase 
of only '26 per cent, of phosphoric acid, and "11 per cent, of 
nitrogen ; ov, in other words, a ton of the compost twice used 
contained only 5'824 lbs., or, in round numbers, 6 lbs. more 
phosphoric acid, an' I 2^ lbs. more nitrogen than the original 
earth. 
Allowing -id. for the value of a pound of phosphoric acid, 
and lOd. for the value of a pound of nitrogen, it will be found 
that the earth twice passed through the closet was worth 10(/. 
more per ton for the phosphoric acid, and 2s. Id. for the nitrogen 
which it contained more than the soil before use ; or, that the 
total value of the earth twice used was 2s. lid., or say 3s., more 
per ton than a ton of dry earth before use. 
On making a similar comparison with the earth thrice used, 
we find in the latter an increase of only '33 per cent, of phos- 
phoric acid, and '20 per cent, of nitrogen ; or, a ton of earth 
thrice used contained 7 '39 lbs. more phosphoric acid, and only 
4'48 lbs., or in round numbers, 4J lbs. more nitrogen than the 
soil before use. These figures show an increased money value of 
2j. b^d. in phosj)h()ric acid and 3s. 9^. in nitrogen. ^ In other 
words the earth, j)assed three times through the closet, in a 
perfectly dry state was worth only 6s. 2Ui. more per ton than 
dry garden mould of the composition of the soil employed in 
the experiments. 
If the agricultural value of earth-closet manure is really so 
low as stated by me, how does it happen, it may be asked 
naturally, that market-gardeners and others who have made 
trials with this description of manure, put a value upon it 
varying from 1 to '61. a ton ? In reply to this very pertinent 
question, 1 would say that the high estimate of the value of 
