From the like cause may also proceed subterraneous Thunders and Earthquakes, when sulphureous and nitreous veins being fired, upon rarefaction do force their way through bodies that resist them. Where if the kindled matter be plentiful, and the Mine close and firm about it, subversion of Hills and Towns doth sometimes follow: If scanty, weak, and the Earth hollow or porous, there only ensueth some faint concussion or tremulous and quaking Motion. Surely, a main reason why the Ancients were so imperfect in the doctrine of Meteors, was their ignorance of Gunpowder and Fire-works, which best discover the causes of many thereof. Now therefore he that would destroy the report of Powder, must work upon the Petre; he that would exchange the colour, must think how to alter the Small-coal. For the one, that is, to make white Powder, it is surely many ways feasible: The best I know is by the powder of rotten Willows, Spunk, or Touch-wood prepared, might perhaps make it Russet: and some, as _Beringuccio_ [SN: _In his_ Pyrotechnia.] affirmeth, have promised to make it Red. All which notwithstanding doth little concern the Report, for that, as we have shewed, depends on another Ingredient. And therefore also under the colour of black, this principle is very variable; for it is made not onely by _Willow_, _Alder_, _Hazel_, etc. But some above all commend the coals of _Flax_ and _Rushes_, and some also contend the same may be effected with Tinder. As for the other, that is, to destroy the Report, it is reasonably attempted but two ways; either by quite leaving out, or else by silencing the Salt-petre. How to abate the vigour thereof, or silence its bombulation, a way is promised by _Porta_, not only in general terms by some fat bodies, but in particular by _Borax_ and butter mixed in a due proportion; which saith he, will so go off as scarce to be heard by the discharger; and indeed plentifully mixed, it will almost take off the Report, and also the force of the charge. That it may be thus made without Salt-petre, I have met with but one example, that is, of _Alphonsus_ Duke of _Ferrara_ [SN: De examine Salium.], who in the relation of _Brassavolus_ and _Cardan_, invented such a Powder as would discharge a bullet without Report. That therefore white Powder there may be, there is no absurdity; that also such a one as may give no report, we will not deny a possibility. But this however, contrived either with or without Salt-petre, will surely be of little force, and the effects thereof no way to be feared: For as it omits of Report so will it of effectual exclusion, and so the charge be of little force which is excluded. For thus much is reported of that famous Powder of _Alphonsus_, which was not of force enough to kill a Chicken, according to the delivery of _Brassavolus. Jamque pulvis inventus est qui glandem sine bombo projicit, nec tamen vehementer ut vel pullum interficere possit._