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thus supposes the process of bituininization to he the basis,as it were, of the petrifactive process, by which the greaterpart of vegetable fossils have been formed.
“ The earths which are most frequently found to bethe chief constituents of vegetable fossils are silex, lime,and alumine; and, according to the preponderance ofeither of these earths may the fossil be distinguished bythe terms siliceous, calcareous, or aluminous. Unwillingto take liberties with the mode of expression, which com-mon usage has authorized, unless able to supersede thatwhich is already adopted, \ will not urge the adoption ofpetrified wood, silicified wood, &c. which point out thecircumstance of the substance having once been wood, buthaving now assumed an entirely different nature. I cannothowever omit to observe here, that such words as do implya real transmutation may frequently be employed, withoutmeriting that degree of censure which is bestowed on themby M. Daubenton; since, although the stony nature ofsubstances is admitted to be merely the result of an earthyimpregnation, the substances thus impregnated will, Ibelieve, in general be found to have suffered an actualtransmutation,—a total change in their nature, that whichwas ligneous having become bituminous.
“ As the fossil w'ood which appears to exist most abun-dantly, is that which has undergone a siliceous impregna-tion, and as the formation of this species of fossil woodappears to be the most difficult to be explained, we will takeit into consideration. But as its impregnation is hereassumed to have been accomplished by a solution of thesilex in some aqueous menstruum, a circumstance of whichno positive proof can, perhaps, be adduced ; it is necessaryprevious to entering into particular examination of thissubstance itself, to determine what degree of force it pos-sessed, by that collateral evidence, to which we are ne-cessitated to have recourse.
“ So regularly does the earthy matter appear to havebeen diffused through every part of the changed wood, andso intimate is the union which has taken place, that itsdeposition from an aqueous menstruum, in which it hadbeen held either in a state of suspension, or of solution,appears to be obvious. That it has chiefly been depositedin minute crystallizations, which by their regular appositionto each other, have, at length, formed that continuedsiliceous substance, of which these fossils are in generalcomposed, may be almost universally inferred, from thecircumstance of most of these specimens having their sur-