lso because
its properties are such as enable it to act powerfully on the soil,
farm-yard manure must always be of the highest importance. It is, in
fact, the typical manure, and in proportion as other substances approach
it in properties and composition, is their value for general purposes on
the farm.

Farm-yard manure is a mixture of the dung and urine of domestic animals,
with the straw used as litter; and its value and composition must
necessarily depend upon that of these substances, as well as on the
proportion in which they are mixed. The dung of animals consists of that
part of their food which passes through the intestinal canal without
undergoing assimilation; the urine containing the portion which has been
assimilated and is again excreted, in consequence of the changes which
are proceeding in the tissues of the animal. Their composition is
naturally very different, and must be separately considered.

_Urine._--Urine consists of a variety of earthy and alkaline salts, and
of certain organic substances, generally rich in nitrogen, dissolved in
a large quantity of water. That of the different domestic animals has
been frequently examined, but the analyses of Fromberg give the most
complete view of their manurial value:--

Horse. Swine. Ox. Goat. Sheep.

Extractive matter } 2.132 0.142 2.248 0.100 0.340
soluble in water }
Extractive matter } 2.550 0.387 1.421 0.454 3.330
soluble in spirit}
Salts soluble in } 2.340 0.909 2.442 0.850 1.957
water }
Salts insoluble in} 1.880 0.088 0.155 0.080 0.052
water }
Urea 1.244 0.273 1.976 0.378 1.262
Hippuric acid 1.260 ... 0.550 0.125 ...
Mucus 0.005 0.005 0.007 0.006 0.025
Water 88.589 98.196 91.201 98.007 92.897
------ ------- ------- ------- -------
100.000 100.000 100.000 100.000 99.863

_Composition of the Ash of these Urines._

Horse. Swine. Ox. Goat. Sheep.
Carbonate of lime 12.50 ... 1.07 trace 0.82
Carbonate of magnesia 9.46 ... 6.93 7.3 0.46
Carbonate of potash 46.09 12.10 77.28 trace ...
Carbonate of soda 10.33 ... ... 53.0 42.25
Sulphate of potash ... ... 13.30 ... 2.98
Sulphate of soda