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left ; containing the earths and other solid matters, which preceding 

 vegetation had subtracted from the earth's surface. This sub- 



^ 



stance, which is termed humus, or virgin mould f 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. Con- 

 taining so many of the principles which are requisite to the forma- 

 tion of vegetable matter, and greedily attractive from the super- 

 ambient air, of oxygen, the dissolvent principle of the various sub- 

 stances absorbed by vegetables, it may be considered as the grand 

 reservoir of the food of plants. Its soft and yielding nature, ren- 

 ders it, at the same time, a matrix fitted to promote the process of 

 germination, and for the free diffusion and divarication of the ten- 

 der 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 dissappearance, 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. M 



