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sense, in which it has been already applied to fossil wood, into theinterstices of which clay has freely penetrated.

On putting a piece of this wood, impregnated with lime, intodiluted nitric acid, the same effects were produced as when othercalcareous fossil wood was subjected to the same experiment. Thecarbonate of lime was decomposed, and, on the earth being re-moved, the fibres of the wood were found in a loose and detachedstate; of a dark brown colour, and burning with a white flame, anda bituminous odour, on being applied to the flame of a candle.

I have, in a former Letter, remarked that the process of bitumi-nization seems to be inimical to animal life; and that, after anyvegetable substance has been exposed to its influence, it appears tobe no longer fitted to become the aliment of any animal. Naturehaving now destined this matter to undergo a peculiar chemicalchange, the first step is to prevent its being subject to any otherkind of alteration, which might interfere with this arrangement.This is confirmed by the appearance of these specimens, in whichthe wood has evidently been exposed to the process of bituminiza-tion, since it had been subjected to the ravages of the teredines.These pieces of wood, I, therefore, conjecture to have lain in thesea, subjected to the devastating labours of these animals, until,by some of those changes, of which a former letter has aimed togive, at least, some slight notion, they became overwhelmed withearth; and that, while thus buried, and secluded from the atmos-phere, they passed into the bituminous fermentation ; and after-wards, from the infiltration of certain lapidific juices, obtained theirpresent form of existence*.

* It seems to be deserving of trial, whether slightly bituminized wood might not be ad-vantageously employed for ship’s bottoms, and for other purposes, in which the ravagesof the ship-worm are particularly required to be guarded against. It even seems desirablethat it should be ascertained, how far wood which has been involved in hay whilst formingin the rick, would be protected against these animals.