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Niter, conjoining themselves again by means of the Salt, to resume their pristine forme. Nor will Niter (adds he) or Allum, or Vitriol, if well purged, ever return into common escuflent Salt.
Yet this he grants to Kircher, that common Salt will turn into Niter, Alum, and Vitriol, when it hath changed its particles by the motion of subterraneous Fires, and so being comminuted into small particles hath converted its former Salt-taste into a present acid one, yet so as that for the composition of Niter there must be mixt some ramenta of Lixiviat Salt; for that of Alum, some ramenta of Lead; for that of Vitriol or Copperas, some of Iron or Copper.
Yet however this be, he denies, that there should lye concealed in the Center of common or Nitrous Salt any thing; that is unchangeable, coagulating and fixing all things; because an Artist can without any great difficulty bring both these Salts wholly over the Helme, and reduce them into a volatil Spirit, with but a very little sediment left behind; and can also reduce them both into an insipid Earth destitute of all vertue or operation, but only that, which is a little (but very little) adstringent; as may be seen by Blasius Vigenere, in his Tract de igne & Sale, but by his own Experiment affirmed to have been often and easily made; so as that the most purifyed salt, having its pungency obtunded by a fit and often repeated fire (whereby it may be often freed, dissolved, coagulated) will affect the tongue no more, than common Potters Earth.
Here he censureth, what Kircher affirms in his Mund, Subterr. viz. That in salt, how -much soever depurated, there will be found a true Earth, which though seemingly destitute of all salt, yet being for some dayes exposed to a clear sky and the Sun, will be again impregnated with new salt. To which he declares, that if Kircher had continued his method of purging salt to the utmost, he would have found, that the whole body of salt would have been at last thus changed into a saltless Earth, altogether inefficacious, save a little adstringency; directing withall, that he should have farther burnt the Earth, which he thought destitute of all salt, thoroughly,
