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the absence and return of the ambient Air, as might with any probability have the loss or recovery of the Woods splendour attributed to it. For I had formerly (if I were not mistaken) found by several circumstances, which I shall not now stay to name, That a flight (so it be an appropriated) variation of the Texture of this Wood, and which may seem mainly to respect the Pores (which perhaps ought to be of a determinate shape and size, and filled with a determinate matter) will have a great operation upon its splendour. And I formerly found by other Trials, that even consistent Bodies, if soft ones, may have their Pores enlarged and vitiated, and their bulk, and consequently their texture (at least as to their Pores) manifestly enough alter'd, by having the Air withdrawn From about them (whereby the Aerial Particles within them were enabled to expand themselves) and let in again, whereby, as to sense, they seemed pretty well restored to their former state. But the success of my endeavours either with Microscopes (through which a vivid piece of Wood will shine by its own light) or otherwise, was not considerable enough to deserve a particular account, especially in this Paper, where I am not to venture at matter of Theory.
Experiment VI.
Thinking fit to try, Whether a small quantity of Air, with out being ventilated or renewed, might not suffice to maintain this cold Eire, though it will not that of a Live Coal, or a piece of Match, we caused a piece of shining Wood to be Hermetically sealed up in a pipe of clear and thin Glass; but though ca-trying it into the dark, we found it had quite lost its light, yet imagining that that might proceed from its having been overheated (being sealed up in a Pipe not long enough to afford it a due distance from the flame of the Lamp we employ'd to seal it) we caused two -or three pieces of fresh Wood, amounting all of them to the length of about two inches, to be seal'd up in a slender pipe between four or five inches in length; which being warily done, the Wood retained its light very well, when the Operation was over; and afterwards laying it by my bed-side, when the Candles were carried away out of the Room, I consi-
