------ ----- -----
100.00 100.0 100.0

They are extremely prone to change, and in presence of animal matters
readily ferment, and are converted into salts of ammonia. Thus human
urine, which, at the time of emission is free from smell of ammonia, and
has a slightly acid reaction, becomes highly ammoniacal if it be kept
for a few days. This is due to the conversion of urea into carbonate of
ammonia; and the same change takes place, though more slowly, with uric
and hippuric acids.

It is obvious, from the foregoing analyses, that great differences must
exist in the manurial value of the urine of different animals. Not only
do they vary greatly in the proportion of solid matters which they
contain, but also in the kind and quantity of their nitrogenous
constituents. They differ also in regard to their saline ingredients;
and while salts of potash and soda form the principal part of the ash of
the urine of the ox, sheep, goat, and horse, and phosphoric acid and
phosphates are entirely absent, that of the pig contains a considerable
quantity of the latter substances, and in this respect more nearly
resembles the urine of man. Human urine is also much richer in urea and
nitrogenous constituents generally, and has a higher value than any of
the others.

It is especially worthy of notice that the urine of the purely
herbivorous animals (with the exception of the sheep, which contains a
small quantity), are devoid of phosphates and urea; and consequently,
when employed alone, they are not general manures--a matter of some
importance in relation to the subject of liquid manuring, which will be
afterwards discussed.

_Dung._--The solid excrement of animals is equally variable in
composition. That of the domestic animals which had the ordinary winter
food was found to have the following composition:--

Horse. Cow. Sheep. Swine.
Per-centage of water in the } 77.25 82.45 56.47 77.13
fresh excrement }
Ash in the dry excrement 13.36 15.23 13.49 37.17

100 parts of ash contained--

Horse. Cow. Sheep. Swine.
Silica 62.40 62.54 50.11 13.19
Potash 11.30 2.91 8.32 3.60
Soda 1.98 0.98 3.28 3.44
Chloride of sodium 0.03 0.23 0.14 0.89
Phosphate of iron 2.73 8.93