Carbonic acid is the most abundant gaseous product of the peaty decomposition. Since it contains nearly 73 per cent. of oxygen and but 27 per cent. of carbon, it is obvious that by its escape the proportion of carbon in the residual mass is increased. In the formation of water from the decaying matters, 1 part of hydrogen carries off 8 parts of oxygen, and this change increases the proportion of carbon and of hydrogen. Marsh gas consists of one part of hydrogen to three of carbon, but it is evolved in comparatively small quantity, and hence has no effect in diminishing the per cent. of carbon.
The gas that bubbles up through the water of a peat-bog, especially if the decomposing matters at the bottom be stirred, consists largely of marsh gas and nitrogen, often with but a small proportion of carbonic acid. Thus Websky found in gas from a peat-bed
| Carbonic acid | 2.97 |
| Marsh gas | 43.36 |
| Nitrogen | 53.67 |
| 100.00 |
Carbonic acid, however, dissolves to a considerable extent in water, and is furthermore absorbed by the living vegetation, which is not true of marsh gas and nitrogen; hence the latter escape while the former does not. Nitrogen escapes in the uncombined state, as it always (or usually) does in the decay of vegetable and animal matters that contain it. Its loss is, in general, slower than that of the other elements, and it sometimes accumulates in the peat in considerable quantity. A small portion of nitrogen unites with hydrogen, forming ammonia, which remains combined with the humic and other acids.
[PART II.]
ON THE AGRICULTURAL USES OF PEAT AND SWAMP MUCK.
After the foregoing account of the composition of peat, we may proceed to notice:
1.—The characters that adapt it for agricultural uses.