, which
rapidly increases, until we have a fair percentage of humus accumulated.

[81] See Appendix, Note V., p. 158.

[82] See Historical Introduction, pp. 40-45.

[83] The evidence demonstrating this is to be found in the fact that the
amount of carbon found in different soils rises or falls in proportion
to the nitrogen. See p. 126.

[84] See Chapter IV. on Nitrification.

[85] Diffusion as well as capillary attraction is a means of bringing
nitrates again to the surface-soil after rain.

[86] See Appendix, Note VI., p. 158, and Note VIII., p. 160; also p.
154.

[87] See Appendix, Note VII., p. 159.

[88] See following Chapter on Nitrification, p. 178.

[89] According to the Agricultural Returns for 1888, the number of cows
in milk in Great Britain amounted to 2,450,444. If we multiply this
number by 22 the result is 54,000,000 lb., or in tons 24,107. This
quantity represents 154,067 tons of ordinary commercial nitrate of soda.

[90] For 1878 (p. 146 _et seq._) The reader interested in the subject is
referred to the paper itself.

[91] In tons 4464, and represents 28,530 tons of nitrate of soda.

[92] This in tons 162,946, which represents 1,041,384 tons of nitrate of
soda.

[93] This in tons 40,625, which represents 259,633 tons of nitrate of
soda. See paper in 'Journal of Science' already referred to.

[94] Europe's total production may be stated at 200,000 tons.

[95] 10,500 tons of which were as guano.

[96] Mr Warington estimates this at about 8 lb. See p. 141.

APPENDIX TO CHAPTER III.

NOTE I. (p. 119).

DETERMINATIONS OF THE QUANTITY OF NITROGEN SUPPLIED BY RAIN, AS
AMMONIA AND NITRIC ACID, TO AN ACRE OF LAND, DURING ONE YEAR.

(_From Dr Fream's 'Soils and their Properties_,' p. 62.)

----------------------+----------------+---------+----------------+--------
| | | Nitrogen per |
| | | million, as | Total
| | +--------+-------+Nitrogen
| Year. |Rainfall.| | | per
| | |Ammonia.| Nitric| acre.
| | | | Acid. |
----------------------+----------------+---------+--------+-------+--------
| | | | | lb.
Kuschen | 1864-65 | 11.