| | |
| potassium | ... | ... | 58.42 26.59 | 25.83 | 9.10 |
|Iodide of | | | | | |
| potassium | 0.44 | 0.23 | 1.51 2.09 | 1.22 | 1.68 |
|Soda | 4.58 | 6.09 | ... ... | ... | ... |
|Sulphuret | | | | | |
| of sodium[M]| 3.66 | ... | ... ... | ... | ... |
|Chloride | | | | | |
| of sodium | 24.33 | 24.81 | 15.29 30.77 | 19.34 | 22.08 |
|Phosphoric acid | 1.71 | 2.14 | 2.42 2.66 | 1.75 | 4.59 |
|Sulphuric acid | 21.97 | 28.01 | 2.23 8.80 | 7.26 | 6.22 |
|Carbonic acid | 6.39 | 2.20 | 4.11 2.49 | 15.23 | 13.58 |
|Silicic acid | 0.38 | 0.67 | 0.33 0.99 | 1.20 | 3.00 |
| | ----- | ------ | ------ ------ | ------ | ------ |
| |100.00 | 100.00 | 100.00 100.00 | 100.00 | 100.00 |
+----------------+--------+----------+----------------+-----------+-----------+

The first four analyses give the composition of the weeds after they
have been separated from all foreign substances; the last, that of the
mixture taken from the heap just as it is used in Orkney; and its value
is then enhanced by small shells and marine animals adhering to the
plants, which increase the amount of phosphoric acid and nitrogen.

The ease with which all sea-weeds pass into a state of putrefaction,
adapts them in a peculiar manner to the manurial requirements of a cold
and damp climate. The rapidity of their decomposition is such, that when
spread on the land they are seen to soften and disappear in a short
time. They form therefore a rapid manure, and their effects are said to
be confined to the crop to which they are applied; but this is probably
due to the fact, that they are chiefly used in inferior sandy soils, in
which any manure is rapidly exhausted. In good soils there is no reason
why their effect should not be as lasting as that of farm-yard manure,
which, in many particulars, they considerably resemble. The method of
applying sea-weeds most generally in use, is to spread them on the soil,
and plough them in after putrefaction has commenced, and it is on the
whole the most advantageous. But