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placed in our Receiver, gave a yet weaker found when the Air was withdrawn from about it, than when the Receiver was full of Air: I presumed, some curious persons would, if they had been present, desire to have a trial made, whether or no a small piece of Shining Wood being so included in the Receiver, as that the pumping out of the Air should have no injurious operation upon the body of it, its Light would upon the withdrawing of the Air be manifestly diminish'd. And this I was the less backward to try, because (not to mention the Relation, which the former Experiments shew there may be in some cases between Light and Air) it did not readily occur to my memory, that by any manifest Experiment (for I know, there are probable Reasons to prove it) it appeared, that a Body more thin than Air will or can transmit Light, as well as other diaphanous mediums. And those modern Atomists, that think, there is in our exhausted Receiver very many times more Vacuum than Body, would, I presumed, be glad to be supplied with an Argument against the Peripateticks, to shew, That at the motion of Bodies, viz. the Corpuscles of Light, may be freely made in Vacuo, and proceed without the assistance of a Vehicle.
Wherefore having Hermetically sealed up a small piece of Shining Wood in a slender Pipe, and placed it in a small Receiver that was likewise made of clear Glass, we exhausted it of Air, and afterwards let in again that which we had excluded. But neither of the Operations could we perceive any sensible decrement or encrease of the Light of the Wood, though by that very Observation it appeared, that the Glass had been well sealed, since otherwise the included Air would have got out of the Pipe into the Receiver, and have left the Wood without Light.
Experiment IX.
I had also a mind to try, both what degree of Rarefaction of the Air would deprive the Wood of its splendour in such and such measures, and whether or no the self-same Air, which, when rarified, would not suffer the Wood to shine, would, when reduced to its former density, allow it to shine as much as before.
This I proposed to do, by putting some Shining Wood into a
