With respect to the northern limit
at which the climate allows of that peculiar kind of slow decomposition
which is necessary for its production, I believe that in Chiloe (lat. 41 deg.
to 42 deg.), although there is much swampy ground, no well characterised peat
occurs; but in the Chonos Islands, three degrees farther southward, we
have seen that it is abundant. On the eastern coast in La Plata (lat.
35 deg.) I was told by a Spanish resident, who had visited Ireland, that he
had often sought for this substance, but had never been able to find any.
He showed me, as the nearest approach to it which he had discovered, a
black peaty soil, so penetrated with roots as to allow of an extremely
slow and imperfect combustion."
The next stage in the making of coal is one in which the change has
proceeded a long way from the starting-point. _Lignite_ is the name which
has been applied to a form of impure coal, which sometimes goes under the
name of "brown coal." It is not a true coal, and is a very long way from
that final stage to which it must attain ere it takes rank with the most
valuable of earth's products. From the very commencement, an action has
being going on which has caused the amount of the gaseous constituents to
become less and less, and which has consequently caused the carbon
remaining behind to occupy an increasingly large proportion of the whole
mass. So, when we arrive at the lignite stage, we find that a
considerable quantity of volatile matter has already been parted with,
and that the carbon, which in ordinary living wood is about 50 per cent.
Pages:
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73