il-particles, all its soluble phosphate is converted into
precipitated phosphate.

NOTE VII. (p. 326).

ANALYSES OF DUNG OF FOWLS, PIGEONS, DUCKS, AND GEESE. (Storer's
'Agricultural Chemistry,' vol. i. p. 367.)

Fowls. Pigeons. Ducks. Geese.
Water 56.00 52.00 56.60 77.10
Organic matter 25.50 31.00 26.20 13.40
Nitrogen 1.60 1.75 1.00 .55
Phosphoric acid 1.5-2.00 1.5-2.00 1.40 .54
Potash .80-.90 1.0-1.25 .62 .95
Lime 2.00-2.50 1.5-2.00 1.70 .84
Magnesia .75 .50 .35 .20

According to a computation by a Belgian farmer, a pigeon yields about 6
lb. of dung in a year, a hen about 12 lb., a turkey or goose about 25
lb., and a duck 18 lb.

CHAPTER IX.

NITRATE OF SODA.

Nitrate of soda,[202] or, as it is more correctly designated from a
chemical point of view, sodium nitrate, now forms the chief artificial
nitrogenous manure in use. Along with sulphate of ammonia, it has taken
the place once held in the manure markets by the older Peruvian guano,
and may without doubt be reckoned, at present prices, one of the
cheapest and most valuable of the artificial sources of nitrogen for the
plant. It is some sixty-two years ago since it was first exported from
South America into this country. The total exports in that year amounted
to about 800 tons, and some indication of the enormous extent to which
the use of this valuable fertiliser has been developed since then will
be obtained from the statement that the total exports at present amount
to little less than 1,000,000 tons per annum, representing a monetary
value of 6 to 7 millions sterling. Of this quantity about 120,000 tons
are imported into Britain.[203] While its chief use is for manurial
purposes, it must not be imagined that it is only used for this purpose.
A certain amount is used in connection with various chemical
manufactures--for instance, that of nitric and sulphuric acid--and also
in the manufacture of saltpetre, the chief constituent of gunpowder.

_Date of Discovery of Nitrate Deposits._

The exact date of the discovery of the nitrate deposits seems to be a
point of considerable dubiety. The earliest published description of
them was written by Bollaert about the year 1820, in which year, it is
stated, the first shipment was ma