--The use of the sewage of towns as a manure is closely
connected with that of the liquid manure produced on the farm. Its
application must take place in a similar manner, and be governed by the
same principles. Although numerous attempts have been made to convert it
into a solid form, or to precipitate its valuable matter, none of them
have succeeded; nor can it be expected that any plan can be devised for
the purpose, because the most important manurial constituents are
chiefly soluble, and cannot be converted into an insoluble state, or
precipitated from their solution. In its liquid form, however, sewage
manure has been employed with the best possible effect in the
cultivation of meadows. The most important instance of its application
is in the neighbourhood of Edinburgh, where 325 acres receive the sewage
of nearly half the town, and have been converted from barren sand into
land which yields from L20 to L30 per acre. The contents of the sewer,
taken just before it flows into the first irrigated meadow, near
Lochend, were found to contain per gallon--

Soluble organic matter 21.90
Insoluble organic matter 21.70
Peroxide of iron and alumina 2.01
Lime 10.50
Magnesia 2.00
Sulphuric acid 6.09
Phosphoric acid 6.14
-----
Chlorine 12.20
Potash 2.89
Soda 13.27
Silica 6.50
------
105.20
Ammonia 14.90

It is interesting to notice that this sewage is superior in every
respect to the liquid manure used at Tiptree Hall; and the good effects
obtained from its application, in the large quantities in which it is
used in the Craigentinny meadows, may be well imagined. It operates, not
merely by the substances which it holds in solution, but also by
depositing a large quantity of matters carried along in suspension, and
is in reality warping with a substance greatly superior to river-mud. A
deposit collected in a tank, where the sewage passes through a farm, is
used as a manure, and contains--

Peroxide of iron and alumina 4.45
Lime 1.74
Magnesia 0.39
Potash