Page:Philosophical Transactions - Volume 002.djvu/209

 several fragments, did either destroy or considerably alter the Light.

This Experiment I repeated with the same success. But what a stronger or more lasting Compression may do in this case, I had not opportunity to try.

2. The next unlikeness to be taken notice of betwixt Rotten Wood and a Kindred Goal, is, What the latter will in very few minutes be totally extinguisht by the withdrawing of the Air, whereas a piece of Shining Wood, being eclipsed by the absence of the Air, and kept for a time, will immediate recover its Light, if the Air be let in upon it again within half an hour after it was first withdrawn.

The former part of this Observation is easily proved by the Experiments that have been often made upon Quick Coals in the Pneumatical Engine; and the truth of the latter part appears by an Experiment about Shining Wood made by us in October last. Neither is it unprovable, that if I had had convenience to try it, I should have found, that a piece of Shining Wood, deprived of its light by the removal of the ambient Air, would retain a disposition to recover it upon the return of the Air, not only for half an hour, (which is all that I lately asserted) but for half a day, and perhaps a longer time.

3. The next difference to he mentioned, is, That a Live Coal being put into a small close Glass, will not continue to burn for very many minutes; but a piece of Shining Wood will continue to shine for some whole days.

The first part of the Assertion I know you will readily grant, and the rather, because it contains matter of fact, without at all determining, whether the Coals not continuing to burn, proceeds from its being, as it were, stifled by its own smoak and exhalations, (which can have no vent in a small close Glass) or from the want of fresh Air, or from any particular cause, which I must not here debate; though I have sometimes made Experiments somewhat odd to facilitate that enquiry. The other part of our Observation may be easily made out by what I tried upon Shining Wood, sealed up Hermetically in very small Glasses, where the Wood did for several days (though I remember not precisely how many) retain its Light. 4. A