10 
IMPERIAL COLLEGE OP 
The question, how much ammonia escapes while the 
dung is fermenting and being stored might be decided by- 
estimations of the nitrogen in several subsequent periods of 
a given weight of excreta, if at the same time the quantity 
of water lost by evaporation is determined by weighing or 
measuring the whole of the dung. In experimenting, 
however, on large volumes, as is unavoidable in this case, 
the operations of ascertaining the weight or volume are not 
veiy convenient ; for which reason it appeared to me to be 
the most accurate and easy way, to estimate at several pe¬ 
riods besides the nitrogen, also the chlorine, an ingredient 
occurring in a large proportion in the dung, especially as 
this is not liable to evaporation or precipitation while the 
whole mass is stored, and as it admits of a very reliable 
analytical method for its quantitative determination. If 
water evaporates, the percentage of chlorine must show a 
proportional increase, from which the quantity of water 
lost can be calculated, and if ammonia escapes, the original 
proportion between chlorine and nitrogen must alter, e. g., 
for every part of chlorine less nitrogen will be found than 
in the original fresh dung. We proceeded in the following- 
way : 
A glazed earthenware vessel, 3 feet in diameter and 4 
feet in depth, rather conically shaped toward the bottom was 
imbedded in the earth up to about an inch from the mouth, 
and filled with about 700 liters of excreta that had been 
collected during the preceding 8-10 daj ? s from the houses of 
officials. This was poured into the above vessel after having- 
been well mixed and strained through a sieve with meshes 
wide enough to retain foreign substances, but not dung. 
The vessel was covered with a straw roof resting on a 
hurdle-work of bamboo, which did not interfere with good 
