the same refraction with such stony particles, as may be discover’d by Sand view’d with a Microscope) into those pores which were formerly repleat with air (that has a very differing refraction, and consequently is very reflective) which seems to be confirm’d by the second Observable, namely, the increase of weight after keeping, and decrease upon drying.  And thirdly, seem’d yet more sensibly confirm’d by the multitude of bubbles in the last Experiment.

We find also most Acid Salts very readily to dissolve and separate the parts of this body one from another; which is yet a further Argument to confirm the porousness of bodies, and will serve as such, to shew that even Glass also has an abundance of pores in it, since there are several liquors, that with long staying in a Glass, will so Corrode and eat into it, as at last, to make it pervious to the liquor it contain’d, of which I have seen very many Instances.

Since therefore we find by other proofs, that many of those bodies which we think the most solid ones, and appear so to our sight, have notwithstanding abundance of those grosser kind of pores, which will admit several kinds of liquors into them, why should we not believe that Glass, and all other transparent bodies abound with them, since we have many other arguments, besides the propagation of light, which seem to argue for it?

And whereas it may be objected, that the propagation of light is no argument that there are those atomical pores in glass, since there are Hypotheses plausible enough to solve those Phaenomena, by supposing the pulse onely to be communicated through the transparent body.

To this I answer, that that Hypothesis which the industrious Mersennus has publish’d about the slower motion of the end of a Ray in a denser medium, then in a more rare and thin, seems altogether unsufficient to solve abundance of Phaenomena, of which this is not the least considerable, that it is impossible from that supposition, that any colours should be generated from the refraction of the Rays; for since by that Hypothesis the undulating pulse is always carried perpendicular, or at right angles with the Ray or Line of direction, it follows, that the stroke of the pulse of light, after it has been once or twice refracted (through a Prisme, for example) must affect the eye with the same kind of stroke as if it had not been refracted at all.  Nor will it be enough for a Defendant of that Hypothesis, to say, that perhaps it is because the refractions have made the Rays more weak, for if so, then two refractions in the two parallel sides of a Quadrangular Prisme would produce colours, but we have no such Phaenomena produc’d.

There are several Arguments that I could bring to evince that there are in all transparent bodies such atomical pores.  And that there is such a fluid body as I am arguing for, which is the medium, or Instrument, by which the pulse of Light is convey’d from the lucid body to the enlightn’d.  But that it being a digression from the Observations I was recording, about the Pores of Kettering Stone, it would be too much such, if I should protract it too long; and therefore I shall proceed to the next Observation.