d _phosphatic_.

I.--NITROGENOUS GUANOS.

(_a_) PERUVIAN.

By far the most valuable and abundant deposits as yet discovered have
been those on the Peruvian and Chilian coasts. As already pointed out,
guano seems to have been used in this country from a very early period;
and so impressed were the Incas with its importance as a manure, that
the penalty of death was imposed on any one guilty of killing the
sea-fowl during the breeding season in the vicinity of the deposits.

The occurrence of guano in Peru seems first to have been made known in
Europe in the beginning of the eighteenth century. It was not, however,
till the beginning of the present century--viz., 1804--that A. Humboldt,
the great German traveller, brought some of the wonderful fertiliser
home with him, and that its composition was able to be investigated by
chemical analysis. Shortly afterwards, its practical value was
demonstrated by experiments carried out on potatoes by General Beatson
in St Helena. To Lord Derby is due the credit of having first introduced
it into this country, the earliest importation into Liverpool being in
1840. Experiments were shortly afterwards instituted in different parts
of the country, prominent among which were those by Sir John Lawes and
Sir James Caird; and so striking were the results obtained, that the
manure rapidly found favour with the farming community--so much so, that
ten years later the importations into this country amounted to no less
than 200,000 tons, while in 1855 the total exports from the west coast
of South America reached the enormous amount of 400,000 tons. In all, it
has been estimated that since the year 1840 over 5,000,000 tons of
Peruvian guano have been imported into this country.

_Different Deposits._

Peruvian guano has been derived from various deposits occurring in
different parts of the coast, and from a number of small adjacent
islands. The richest of these was that found on Angamos, a rocky
promontory on the coast of Bolivia. Samples of this guano contained as
high as 20 per cent of nitrogen (equal to 24 per cent ammonia).[188]
Unfortunately, however, the quantity of this deposit was extremely
limited, and became rapidly exhausted. Next to this deposit in quality
was the guano found on the Chincha islands, three little islands off the
coast of Peru. These deposits were the largest which have ever been
discovered, and for a period of nearly thirty years were almost the sole
source