Of invisible Writing. 351

cible , aud make a strong lye of quick-lime, and laying* linnen cloth over the mouthof the vessel, that must receive it, strain it ; boil it a little, mingle this with your ink,they will remain a while, but in short time the letters will vanish away. Set it upfor you use. But contrarily,if you will

That invisible letters after some ttme^fhallbecome visibleand shew themselves; I will give you some examples, that you may invent morethereby your self. Is you write with juice of Citrons or Oranges, on Copper orBrass, anal leave this so for twenty days, the letters will appear green upon the place -the same may be done many other ways, namely, by dissolving lalt Ammoniac in wa*ter, and writing with it upon Brass,the place will sooner appear of verdigreele-colour,

Chap. X.

How ree may take off letters that are written upon the paper.

I F we would take letters from off the paper, or that such as are blotted out mightappear again , we must use this art. As, if we would

Take letters off the paper ,

or from parchment: Take Aqua fortis , that is it that parts gold from silver: with apensil wipe some of this upon the letters, it will presently wipe off letters , writtenwith Gall and Copras. If you use Aquafortis , wherein salt Ammoniac is dissolved,it will be sooner done. But printed letters arc harder taken out, because that inkhath neither Galls nor Copras: Or rub it with salt Alkali and Sulphur, making littleballs of them, and that will eat them out, that nothing shall be seen. But if youdesire to write any thing in the place you have made clean , first, wet the place withwater, wherein Alcmis dissolved, for the ink will not run abour. If you desire

To renew letters decayed ,

or to read such as ire vanished: Boil Galls in wine, and with a spunge wipe over theletters, the levers will presently be seen, when they are once wet thus, and be wellcoloured as they were at first.

Chap. XI.

How to counterfeit a seal and writing.

IT may be of great use when places are besieged, and in Armies, and affairs of greatmen, to know how to open letters, that are sealed with the Generals Seal, andsigned with his Name, to know what is contained within , and to seal them again,writing others that are contrary to them, and the like, I will shew how

To counterfeit the Seal.

Melt Sulphur,and cast it into powder of Ceruse, while it is melted; put this mixtureupon the Seal, but fence it about with paper or wax, or chalk, and press it down;when it is cold, take it eff, and in that shall you have the print of the Seal. I willdoit another way. Fill an earthen pot with Vinegar, cast Vitriol into it, and agood deal of Verdigreese; let it bubble on the fire, put plates os iron into it; after ashort time take them out, and from theout-side with your knife, scrape ossa kind ofrust it hath contracted , that is durty as it were, and put this into a dish under it:again, pm them into the earthen pot, and scrape more eff when you take them cut jdo this so often, till you have seme quantity of this durty substance: cast quick-silverinto thiz, and make a mixture; and while it is soft ard tende,I»y it on the Seal, andpress it down, and let it remain in the open Air, for it will grow so hard, that youmay almost seal with it; for it will become even like to a Metal. It may be also doneanother way: Take the filings of steel, and put them in an earthen Crucible at a

strong