n
analysis has been swallowed in the shape of grains of sand and particles
of soil mechanically mixed with the food, although part is also derived
from the straw and grains, which contain that substance in great
abundance. The difference in the quantity of nitrogen they contain is
also very marked, and is distinctly shown by the following analyses by
Boussingault, which give the quantity of carbon, hydrogen, nitrogen,
oxygen, and ash in the dung and urine of the horse and the cow in their
natural state, and after drying at 212 deg..

+---------+--------------------------+--------------------------+
| | HORSE. | COW. |
| +-------------+------------+-------------+------------+
| | Natural. | Dry. | Natural. | Dry. |
| +-------------+------------+-------------+------------+
| |Urine.| Dung.|Urine.|Dung.|Urine.| Dung.|Urine.|Dung.|
| +------+------+------+-----+------+------+------+-----+
|Carbon | 4.46| 9.56| 36.0| 38.7| 3.18| 4.02| 27.2| 42.8|
|Hydrogen | 0.47| 1.26| 3.8| 5.1| 0.30| 0.49| 2.6| 5.2|
|Nitrogen | 1.55| 0.54| 12.5| 2.2| 0.44| 0.22| 3.8| 2.3|
|Oxygen | 1.40| 9.31| 11.3| 37.7| 3.09| 3.54| 26.4| 37.7|
|Ash | 4.51| 4.02| 36.4| 16.3| 4.68| 1.13| 40.0| 12.0|
|Water | 87.61| 75.31| 0.0| 0.0| 88.31| 90.60| 0.0| 0.0|
| +------+------+------+-----+------+------+------+-----+
| |100.00|100.00| 100.0|100.0|100.00|100.00| 100.0|100.0|
+---------+------+------+------+-----+------+------+------+-----+

Hence, weight for weight, the urine of the horse, in its natural state,
contains three times as much nitrogen as its dung; that of the cow twice
as much; and the difference, especially in the horse, is still more
conspicuous when they are dry.

It is obvious that the quality of farm-yard manure must depend--1. On
the kind of animal from which it is produced; 2. On the quantity of
straw which has been used as litter; 3. On the nature of the food with
which the animals have been supplied; 4. On the extent to which its
valuable constituents have been rendered available by the treatment to
which it has been subjected; and 5. On the care which has been taken to
prevent the escape of the urine, or of the ammonia produced by its
decomposition.

The composition of farm-yard manure has engaged the attention of several
chemists; but there are still many point