Value of Earth-Closet Maiiiii-e. 
195 
bone-dust would supply all the phosphoric acid which was 
contained in 1 ton of dry soil after it had been passed three 
times through the closet. 
The increase of nitrogen in earth-manure I need hardly say is 
likely to be greater in the houses of the wealthy or well-to-do 
people than in prisons or unions, where a less generous diet 
prevails ; and where, consequently, the food is worked out, so to 
speak, more perfectly and the excreta are poorer in nitrogen than 
in the houses of the wealthier and better fed classes. Still, even 
under the most favourable circumstances, the accumulation of 
nitrogen in earth-manure, for reasons which I shall mention 
presently, cannot but be very inconsiderable. 
In proof of this assertion I may quote some trials which Dr. 
Gilbert has lately made with the earth- closet plan. 
Fourteen cwt. of air-dried and sifted clayey soil were set aside 
by Dr. Gilbert for experiment. From one-third to one-half of 
the whole was used before it was necessary to empty the pit. 
When removed the mass appeared uniformly moist throughout, 
and neither faecal matter nor paper was observable in it ; nor 
was the process of emptying accompainied by any offensive 
smell. After exposure, and occasional turning over on the floor 
of a shed, the once used soil was resifted, and again passed 
through the closet. 
The percentage of moisture and of nitrogen in the natural 
soil, and after passing once or twice through the closet, were 
found by Dr. Gilbert as follows : — 
Eitfore use. 
After using 
After Using 
once. 
twice. 
Percentage of moisture in air-dried : 
8 ■ 440 
9-970 
7-:io 
and sifted soil (loss at 212° Fahr. ) / 
Percentage of nitrogen in air-dried 1 
and sifted soil j 
•067 
■216 
•353 
Percentage of nitrogen in soil driedl 
at 212° Fahr / 
•073 
•240 
•383 
Calculated upon the air-dried condition, the increase in the 
percentage of nitrogen was only about 'lo each time the soil was 
used ; and even after using twice. Dr. Gilbert observes, the soil 
was not richer than good garden-mould, and he adds, " It is 
obvious, therefore, that such a manure, even if disposed of free 
of charge, would bear carriage to a very short distance only." 
1 tuUy concur in this view of the matter, for my own analyses 
have given me even less favourable results than those on which 
Dr. Gilbert' s opinion is founded. 
C 2 
