As to the resemblance betwixt this Sal armoniac and that which comes from Mount Ætna, where no Coals are supposed to be; whence it seems to follow, that our volatile Salt may proceed from somewhat else than Coal. To which difficulty I answer, that when I deduced ours from Coal, I did not exclude other bituminous substances that are analogous to it, of which I suppose the Country, where Mount Ætna is, affordeth no inconsiderable quantity; neither will it follow, that no Coals have been wrought, therefore there are none; and if trial hath been made, and no Coals found, yet it will be a doubt still, whether those Trials have been sufficient. However it be, yet I think it were not impertinent (by the way) to enquire, whether the sagacious Venetians may not be beholden to Mount Ætna, or some other Subterraneal fires, for the great quantity of Sal armoniac they sell to our Merchants: for this Fire affordeth no inconsiderable quantity thereof, especially in dry weather; some of which I have sent by my worthy and honoured Friend Mr. Richard Gilpin, who was the person that first brought home part of it from the fire, and in whose company it was first that I experimented it to be Sal armoniac; for till then none took notice of it. And I the rather put this trouble upon him, that by him you may be informed in circumstances that would be tedious to relate.