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other wood : they therefore choose to employ it in those situations 
which are most exposed to injury from that element. Here we 
plainly perceive an instance of the powerfully pervading influence 
of this species of fermentation— trees so little altered in their struc- 
ture as to bear all the ordinary operations of hewing, &c. in the 
same manner as common timber, are found to be so far bitu- 
minized, to their very centre, as to have become, when dried, in a 
considerable degree impenetrable to water ; a property possessed 
by all bituminous matter, after having been once dried, in propor- 
tion to the degree of perfection to which their bituminization has 
proceeded. 
That the leaves, and other soft parts of plants, should suffer con- 
siderable change by this, or by any other species of fermentation 
to which they are subjected, is by no means difficult to understand ; 
but that large solid trunks of trees should thus be penetrated, by 
this peculiar influence, to their very centre, and that too m those 
kinds of woods the substance of which is naturally very dense, 
cannot but excite interest and surprise. To account for this astonish- 
ing effect, it is necessary to consider the powerful agency of water ; 
which, either existing in a separate state, or as one of the consti- 
tuent parts of the substances exposed to this species of change, 
appears to be as indispensably necessary in this, as in all other fer- 
mentations. It is well known that, by the long continued immer- 
sion in water of a piece of timber, the particles of water may be 
made to insinuate themselves through every part of it ; and when 
the water is impregnated with the leaven of this fermentation, this 
will, of course, be conveyed to every part ; and thus may we account 
for so wonderful a change being effected through the whole sub- 
stance. Hereby we discover that this effect, so astonishing at first 
view, is accomplished by this two -fold action of the water; first, 
by separating, by its interposition, the integrant molecules of the 
wood ; in producing which effect it is perhaps aided by the com- 
