ntage appears to result from carrying on the fermentation of
dung too far, but every disadvantage.

"18. Farm-yard manure becomes deteriorated in value, when kept in heaps
exposed to the weather, the more the longer it is kept.

"19. The loss in manuring matters, which is incurred in keeping
manure-heaps exposed to the weather, is not so much due to the
volatilization of ammonia as to the removal of ammoniacal salts, soluble
nitrogenized organic matters, and valuable mineral matters, by the rain
which falls in the period during which the manure is kept.

"20. If rain is excluded from dung-heaps, or little rain falls at a
time, the loss in ammonia is trifling, and no saline matters, of course,
are removed; but, if much rain falls, especially if it descends in heavy
showers upon the dung-heap, a serious loss in ammonia, soluble organic
matter, phosphate of lime, and salts of potash is incurred, and the
manure becomes rapidly deteriorated in value, whilst at the same time it
is diminished in weight.

"21. Well-rotten dung is more readily affected by the deteriorating
influence of rain than fresh manure.

"22. Practically speaking, all the essentially valuable manuring
constituents are preserved by keeping farm-yard manure under cover.

"23. If the animals have been supplied with plenty of litter, fresh dung
contains an insufficient quantity of water to induce an active
fermentation. In this case, fresh dung can not be properly fermented
under cover, except water or liquid manure is pumped over the heap from
time to time.

"Where much straw is used in the manufacture of dung, and no provision
is made to supply the manure in the pit at any time with the requisite
amount of moisture, it may not be advisable to put up a roof over the
dung-pit. On the other hand, on farms where there is a deficiency of
straw, so that the moisture of the excrements of our domestic animals is
barely absorbed by the litter, the advantage of erecting a roof over the
dung-pit will be found very great.

"24. The worst method of making manure is to produce it by animals kept
in open yards, since a large proportion of valuable fertilizing matters
is wasted in a short time; and after a lapse of twelve months, at least
two-thirds of the substance of the manure is wasted, and only one-third,
inferior in quality to an equal weight of fresh dung, is left behind.

"25. The most rational plan of keeping manure in heaps appears to me
that adopted by