ce
fallacious, as respects their adaptation to the food of animals,
inasmuch as their contents of the ingredients of the blood, i.e. of
substances which can be transformed into flesh, stands in a direct
ratio to their amount of phosphates, without which neither blood nor
flesh can be formed.

Our fields will become more and more deficient in these essential
ingredients of food, in all localities where custom and habits do
not admit the collection of the fluid and solid excrements of man,
and their application to the purposes of agriculture. In a former
letter I showed you how great a waste of phosphates is unavoidable
in England, and referred to the well-known fact that the importation
of bones restored in a most admirable manner the fertility of the
fields exhausted from this cause. In the year 1827 the importation
of bones for manure amounted to 40,000 tons, and Huskisson estimated
their value to be from L 100,000 to L 200,000 sterling. The
importation is still greater at present, but it is far from being
sufficient to supply the waste.

Another proof of the efficacy of the phosphates in restoring
fertility to exhausted land is afforded by the use of the guano--a
manure which, although of recent introduction into England, has
found such general and extensive application.

We believe that the importation of one hundred-weight of guano is
equivalent to the importation of eight hundred-weight of wheat--the
hundred-weight of guano assumes in a time which can be accurately
estimated the form of a quantity of food corresponding to eight
hundred-weight of wheat. The same estimate is applicable in the
valuation of bones.

If it were possible to restore to the soil of England and Scotland
the phosphates which during the last fifty years have been carried
to the sea by the Thames and the Clyde, it would be equivalent to
manuring with millions of hundred-weights of bones, and the produce
of the land would increase one-third, or perhaps double itself, in
five to ten years.

We cannot doubt that the same result would follow if the price of
the guano admitted the application of a quantity to the surface of
the fields, containing as much of the phosphates as have been
withdrawn from them in the same period.

If a rich and cheap source of phosphate of lime and the alkaline
phosphates were open to England, there can be no question that the
importation of foreign corn might be altogether dispensed with after
a short time. For