water a little before boyling, next the sides of the Vessel.
There were also some the like Bubbles on the Surface of the water just over it, as if either some exhalations came out of it, or that it did excite some fermentation in the parts of the water contiguous to it.
There was little sensible difference in the transparency of this Stone, before the putting under water, and after: To be sure the milky-white parts continued as before, but more difference in weight then in the former. For whereas before the putting into the water the weight was 1897128 Graines. After it had lyen in about four and twenty hours the weight was 2027128 Graines, so the difference was, 158128 Graines.
The same Stone was infused in the water scalding hot, and so continued for a while after it was cold, but got no more weight then upon infusing in the cold, neither was there any sensible Difference in the weight both times.
In which Experiment, there are three Observables that seem very manifestly to prove the porousness of these seemingly close bodies: the first is their acquiring a transparency, and losing their whiteness after steeping in water, which will seem the more strongly to argue it, if what I have already said about the making transparent, or clarifying of some bodies, as the white powder of beaten Glass, and the froth of some glutinous transparent liquor be well consider'd; for thereby it will seem rational to think that this transparency arises from the insinuation of the water (which has much 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
