nitric acid. There is also present a small
quantity of ammonia from the atmosphere. Nitrate of ammonia thus
formed would in itself be a manure; but, of course, on the large scale
other nitrates will be formed by mixing the acid with cheap alkalies
which are abundant in nature, soda from common salt, and lime from
limestone.

In this process the excessive heat of the electric discharge really
raises the nitrogen and oxygen of the atmosphere to a point of
temperature at which chemical union is forced; or, in other words, the
nitrogen is compelled to burn and to join in chemical combination with
the oxygen with which formerly it was only in mechanical mixture. When
nitrogen is burning, its flame is not in itself hot enough to ignite
contiguous volumes of the same element;--otherwise indeed our
atmosphere, after a discharge of lightning, would burn itself
out!--but the continuance of an electric discharge forces into
combination just a proportionate quantity of nitrogen. Practically,
therefore, manure in the future will mean electricity, and therefore
power; so that cheap sources of energy are of the greatest importance
to the farmer.

With dynamos driven by steam-engines, the price of
electrically-manufactured nitrate of soda would, according to the
estimate of Sir William Crookes, be L26 per ton, but at Niagara, where
water power is very cheap, not more than L5 per ton. Thus it will be
seen that the cheapness of power due to the presence of the waterfall
makes such a difference in the economic aspects of the problem of the
electrical manufacture of manurial nitrates as to reduce the price to
less than one-fifth! It must be remembered that at the close of the
nineteenth century the electric installation at Niagara is by very
many persons looked upon as being in itself in the nature of an
experiment, but at any rate there seems to be no room for doubt that
the cost of natural power for electrical installations will very soon
be materially reduced. Even at the price quoted, namely L5 per ton,
the cost of nitrate of soda made with electrically combined
atmospheric nitrogen compares very favourably with commercial nitrates
as now imported for agriculture purposes. "Chili nitrate," in fact, is
about fifty per cent. dearer.

When wave-power and other forms of the stored energy of the wind have
been properly harnessed in the service of mankind, the region around
Niagara will only be one of thousands of localities at which
ni