OOTNOTES:

[212] From experiments by Lehmann and others with buckwheat and maize,
it would seem that certain plants may prefer, at certain stages of their
growth, ammonia to nitrates. In the case of maize, ammonia may be
preferred in the early stages of growth, while nitrates are preferred as
it becomes more mature. In view, however, of our present knowledge of
nitrification, it may well be doubted whether the conclusions arrived at
from Lehmann's experiments can be accepted.

[213] As the expense of converting the ammonia present in the ammoniacal
liquor is considerable, the practice of using the liquor itself as a
manure has been advocated; but as an objection to this it must be urged
that, besides being so bulky a manure, the liquor contains various
substances poisonous to plant-life.

[214] See Appendix, p. 358.

[215] Some crops, however, may with advantage be treated with larger
quantities of sulphate of ammonia, such as mangels and potatoes.

APPENDIX TO CHAPTER X.

NOTE (p. 355).

The following table will exhibit the production of sulphate of ammonia
in this country from 1870 to 1892:--

Year. Tons. | Year. Tons.
1870 40,000 | 1882 72,000
1871 41,000 | 1883 75,000
1872 42,000 | 1884 87,000
1873 43,000 | 1885 97,000
1874 45,000 | 1886 106,500
1875 46,000 | 1887 113,700
1876 48,000 | 1888 122,800
1877 52,000 | 1889 132,000
1878 55,000 | 1890 140,000
1879 57,000 | 1891 143,500
1880 60,000 | 1892 157,000
1881 65,000

The following table exhibits the sources, and the respective quantities
from each source, of the last seven years' production:--

1886. 1887. 1888. 1889. 1890. 1891. 1892.

Gas-works 82,500 85,000 93,000 100,000 102,150 107,950 112,000
Iron-works 4,000 5,000 5,300 6,000 5,050 6,300 12,000
Shale-works 18,000 21,000 22,000 23,000 24,750 26,600 28,000
Coke and
carbonising
works 2,000 2,700 2,500 3,000 2,300 2,800 5,000

CHAPTER XI.

BONES

_Early Use of Bones._

A most important