14 
IMPERIAL COLLEGE OE 
substances are still abundant, the warmth of the night-soil, 
attains also its maximum not long after the act of excretion. 
When afterwards the activity of the fungi diminishes and 
finally ceases the temperature of the fermenting mass will 
also fall and finally sink to that of the surrounding air or 
soil. As the evaporation of ammonia is, of course, greatly 
favoured by heat, it will take place at the time of strong 
fermentation to a greater extent than later on, but it will 
never be entirely checked unless there should be no more 
carbonate of ammonia in the dung. In the hot season the 
mass will cool very slowly, and not so much as in the other 
seasons of the year. Hence then the rate of evaporation 
cannot much decrease during the time of storage. 
This is also proved by our researches ; we found in trial 
No. III. (in July and August) the rate of nitrogen lost from 
100 parts of nitrogen originally stored to be as follows : 
Within the 1st. & 2nd. weeks.2.55 parts, 
„ „ 3rd.—5th. „ .2.54 „ 
The evaporation of water which continually takes place, 
while the night-soil is stored, is not considerable, amounting 
to only 31.4 °/ 00 of the total excreta after eleven weeks in 
the spring, and to 24.3 °/oo after five weeks in the hottest 
time of the year. During the winter it seemed to be ac¬ 
complished even at a slightly higher rate than in summer, 
probably on account of differences in the relative moisture of 
the air, which is indeed during the Japanese winter (67 °/ 0 ) 
not so great as it is in the summer (82 °/ 0 ). The presence 
of a large proportion of soluble organic and inorganic com¬ 
pounds in the excreta is the principal reason for the very 
slight extent to which the water is lost. A relation be¬ 
tween the evaporation of ammonium carbonate and that of 
water cannot, of course, be expected, as the tension of their 
vapours is entirely different. 
As already stated, the Japanese farmers are accustomed 
