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left ; containing the earths and other solid matters, which preceding 
vegetation had attracted from the earth’s surface. This substance, 
which is termed humus, or mould, when mixed with clay, sandy 
loam, and other particles of different earths, forms the general crust 
of the dry and habitable part of this globe. Containing so many 
of the principles which are requisite to the formation of vegetable 
matter, and greedily attractive from the superambient air, of 
oxygen, the dissolvent principle of the various substances absorbed 
by vegetables, it may be considered as the grand reservoir of the 
food of plants. Its soft and yielding nature renders it, at the same 
time, a matrix fitted to promote the process of germination, and for 
the free diffusion and divarication of the tender radicles of the 
infant plant. 
The formation of mould is, doubtless, one species, or rather 
mode, of mineralization of vegetable matters, and therefore claims 
the attention it has here received : but as the substance thus pro- 
duced never bears the form of any of the organized substances, 
from which it has derived its existence, we need dwell no further on 
it, except to notice two curious and interesting phenomena, which it 
sometimes offers to our observation. 
The first of the phenomena here meant, is that which is termed 
the Ignis fatuus, or Will of the Wisp. This is well known to be a 
lambent flame, appearing at night, over marshy lands ; and which, 
by its flitting motion, and by the sudden disappearance, and as 
sudden renewal of its flame, serves frequently to mislead the wan- 
dering, and even cautious traveller. 
Dr. Shaw has furnished us with the following curious account of 
the phenomena yielded by this extraordinary meteor, of which he 
was enabled to obtain the closest inspection. He says, that in 
travelling by night, in the beginning of April, through the valleys of 
Mount Ephraim, we were attended, for the space of an hour, with 
an Ignis fatuus, that displayed itself in a variety of extraordinary 
VOL. I. 
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