That Salts with Water do whiten yellow Wax, being melted thin, and exposed to the Air, and often sprinkled with the Salt Water, is sufficiently known, and wants no proof but not better than salt-Nitre it self.
Point VII.
Printers also may add this subject to their Ink, which will cause it to adhere very firmly to the Paper, and render the Letters very fair.
That fixed Salts will readily conjoin Ink with Water, is not unknown, and none better than fixed Nitre, which also excelleth all sharp lixiviums, having a power of cleansing Lead, Tin, Copper, or other Vessels.
Point VIII.
It is convenient for Clock-makers, or Watch-makers, if a Water be destilled from it, which soldereth Iron or Steel, without fire, if a drop of that Aqua-fortis be dropped upon it, whence the Iron growing hot, it presently waxeth soft, as if it had been soldered in the fire by the help of Copper.
If an Aqua-fortis be destilled from Niter and calcined Vitriol (NB. that there must be no Water or Phlegm in the Spirit) and two little pieces of Iron be melted with it, (between which there must be little Filings of Iron) then the Iron groweth hot by the Aqua-fortis, which acteth upon it, and the one will be joined to the other by melting, as if it had been done by the fire. But he that will use that water, must know how to prepare it himself, because such is no where to be found to sell.
Point IX.
All Smiths may by it harden their Files, and other Iron Tools, as durable, as if they had been made of the hardest Steel.
Fixed Salts being mixed with ashes and powder of coals or sand, after that they have remained 24 hours in a close Fire, do harden iron like steel; as is proved before in the third point.