f this guano may contain as much as 10 per cent of
nitrogen, but as a rule it is nearer 8 per cent. A very considerable
variation in the amount of phosphoric acid occurs for the reason above
stated, the guano made from fish-scrap being naturally much richer in
this ingredient than whole-fish guano. The phosphoric acid may be said
to range from 4 to 15 per cent, and there is also a small quantity of
potash present.

Guano is also manufactured in Norway from the carcasses of whales. Such
guano contains from 7-1/2 to 8-1/2 per cent of nitrogen, and about
13-1/2 per cent of phosphoric acid.

In America fish-guano is manufactured to a considerable extent--one
important source being the menhaddo, a coarse sort of herring. This fish
is caught for the sake of its oil, which is extracted by boiling, the
residue being manufactured, after pressing and drying, into guano.

In this country the manufacture of fish-guano is carried out to a
considerable and increasing extent. Formerly it was imported from Norway
to a larger extent than is now the case, the present annual imports
amounting only to 1000 or 2000 tons. The total annual production in the
United Kingdom is probably 7000 or 8000 tons.

_Value of "Fish-Guano."_

That fish-guano is a valuable manure there can be no doubt. What,
however, impairs its value is the fact that, as a rule, it contains a
certain amount of oil. The effect of this oil is to retard fermentation
and decomposition when the guano is applied to the soil, and thus render
its action slower than would otherwise be the case.

When applied to the soil, therefore, every opportunity ought to be
given to promote its fermentation. It is best applied some time before
it is likely to be used. It ought to be well mixed with the
soil-particles, and not allowed to lie on the top of the soil. Its best
effect will be on light well-cultivated soils, which permit of the
access both of sufficient moisture and of sufficient air for rapid
fermentation. Its value as a manure for hops, vines, grass, and
strawberries has been found to be considerable. It has been recommended
to be applied along with farmyard manure; and such a mode of application
is no doubt well suited to promote its decomposition. It has also been
used for mixing with superphosphate of lime. Professor Storer has
advocated a more general use of fish as a manure than is at present the
case. He suggests that even fish not suitable for edible purposes might