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sweat were not furnisht with some efficacious dissolvent to open and pierce them. Where he observes, that the best liquored Boots, and such as are water-proof, will be quickly pierced by the sweat of Horses; adding, that though Riding Post he had, to avoid that inconvenience, rubbed his Boots with a Vernice, which refilled even to Aqua fortis, yet the sweat of the Horses, he rode on, dissolved that fence after the second day of his voyage.
Next, he holds it to be an error, to use Spirit of Vitriol for Whitening the Teeth, Experience shewing, that from the mixture of an Alcaly and the Spirit of Vitriol there results a yellow, and that there is an Alcaly continually transpiring out of the Gumms, as of all the other parts of the Body; whence it must follow, that the Spirit of Vitriol employed to rubb the Teeth, when mixt with that Salt, must tinge them of the same colour.
Then he affirms, that wood rotten hath no Alcaly in it, and that it rots not but upon the account of the exhaling of that Salt. Whence 'tis saith he, that the Venetians, to harden the Timber design'd for building of Ships, sink it green in water, and there leave it many years; which is the cause, that the Alcaly having been hindred from exhaling, the Timber rots not, and becomes as hard in a manner as stone.
We cannot pretermit taking notice, that this Author finds occasion in this Book to explain the way, by which the famous Turnheisser, a German Chymist, made that celebrated N il, half Gold and half Iron, which is shew'd at Florence, in the Repository of the Great Duke of Tuscany: 'Tis said, that that Chymist, having in the presence of that Prince immersed in a certain Oyle the one halfe of a Nail, which appear'd to be all iron, that part, which touched the Oyle, was instantly found to be good Gold. Several persons having examin'd this Nail, and facing the Gold and Iron exceeding well conjoined, were perswaded, that that could not be effected but by a true change of one of those two metals into the other, believing it impossible, they could be soder'd together. But the Author of this Book maketh that a very easy thing, if the Iron be before prepared after a certain manner, which he teacheth; and hepretends
