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64 to place to fly the greatest heat, more easily than it can divorce their Elements (especially without the Assistance of the Air) we see that our Chymists cannot Analyze them in close Vessels, and of other compound Bodies the open Fire can as little separate the Elements. For what can a naked Fire do to Analyze a mixt Bodie, if its component Principles be so minute, and so strictly united, that the Corpuscles of it need less heat to carry them up, than is requisite to divide them into their Principles. So that of some Bodies the Fire cannot in close Vessels make any Analysis at all, and others will in the open Air fly away in the Forms of Flowers or Liquors, before the Heat can prove able to divide them into their Principles. And this may hold, whether the various similar parts of a Concrete be combin’d by Nature or by Art; For in factitious Sal Armoniack we finde the common and the Urinous Salts so well mingled, that both in the open Fire, and in subliming Vessels they rise together as one Salt, which seems in such Vessels irresoluble by Fire alone. For I can shew you Sal Armoniack which after the ninth Sublimation does still retain its