Sea-Weed._--Sea-weeds have been employed from time immemorial as a
manure on the coasts of Scotland and England, in quantities varying from
10 to 20 tons per acre. Their action is necessarily similar to that of
green manure ploughed in, as they contain all the ordinary constituents
of land plants.

The subjoined analyses of three of the most abundant species will
sufficiently indicate their general composition.

+----------------+--------+----------+----------------------------+-----------+
| | | |LAMINARIA DIGITATA. | |
| | | | |Mixed Weeds|
| |Fucus | Fucus +----------------+-----------+in the |
| |nodosus.| vesicu.- | | Stem and |state in |
| | | losus | Collected | Frond |which they |
| | | | in Autumn. | collected |actually |
| | | | | in Spring.|are used |
+----------------+--------+----------+----------------+-----------+-----------+
|Water | 74.31 | 70.57 | 88.69 | 77.31 | 80.44 |
|Albuminous | | | | | |
| compounds | 1.76 | 2.01 | 0.93 | 3.32 | 2.85 |
|Fibre, etc. | 19.04 | 22.05 | 4.92 | 10.39 | 6.40 |
|Ash | 4.89 | 5.37 | 5.46 | 8.98 | 10.31 |
| +--------+----------+----------------+-----------+-----------+
| |100.00 | 100.00 | 100.00 | 100.00 | 100.00 |
|Nitrogen | 0.28 | 0.32 | 0.15 | 0.53 | 0.45 |
| | | | | | |
|The ash | | | | | |
| consisted of | | | | | |
| | | | Stem. Frond. | | |
|Peroxide of iron| 0.25 | 0.35 | 0.20 0.50 | 0.45 | 2.35 |
|Lime | 9.60 | 8.92 | 7.21 7.29 | 4.62 | 18.15 |
|Magnesia | 6.65 | 5.83 | 2.73 5.91 | 10.94 | 6.48 |
|Potash | 20.03 | 20.75 | 5.55 11.91 | 12.16 | 12.77 |
|Chloride of | | |