This is the 3rd part of an ongoing project, wherein I recreate
Book Sixteen “Of Invisible Writing” from Neopoliani Magiae Naturalis,
a 16th century text on pre-Newtonian science. Accompanying the 17th century English translation of this work are photographs and commentary of my recreations.
The following excerpts are from Natural Magic (Magiae Naturalis) written by Giambattista della Porta (1537-1615) in 1584 A.D. Transcribed from 1658 English Edition, Printed for Thomas Young and Samual Speed, at the Three Pigeons, and at the Angel in St Paul’s Church-yard.
For this project we will be exploring:
Chapter III “How Letters rubbed with dust may be seen.”
Now I will use another artifice, that letters rubbed with dust may be read, that were before invisible, which I read was used by the ancients. Wherefore do thus,
“That Letters rubbed with mill dust may be read.”
That as in paper, so on some unseen parts of the body, letters written may lie hid, and be opened when need is. Write secretly on your back or arms, or other limbs, with Vinegar or Urine, and dry it that nothing may appear. Now, to have it read, rub it over with soot or burnt paper, for so the letters will shine forth. Or,
If you make letters with fat, Tallow or any other fatty substance, or with Gum, or milk of a Fig tree, and strew them with dust of coal or burnt paper, they will appear. It may be by this craft, as Polyanus the Greek says, Attalus used the imprinted inscription of a beast for sacrifice. He, to raise the valor of his Soldiers, to make them fight valiantly with their enemies, the French, that were far more in number, supposing it would be no little advantage to put them in hopes before hand of the assurance of victory, invented a trivial business, but otherwise profitable, with the priest that was to offer sacrifice. Before the day they were to fight, he prepared for the victory. For Sudinus the Soothsayer, being to offer sacrifice, prayed unto the gods, and cuts the sacrifice in two. But the king used powdered Gum, and from the right to the left side, the drew these words, “Regis Victoria,” “…the Victory is the King’s…,” And when the entrails were drawn forth, he thrust his hand into the hottest and most spongy place, and wiped clean the inscription. But the Auger, changing the other parts, and doing his office, turns the part where this inscription was contained, “Regis Victoria.” The matter was no sooner published, but theSoldier generally rejoiced, and shouted exceedingly, to show how ready they were to fight, so going on with a certain assurance of the victory. And depending on this promise from the gods, they fought courageously, and subdued the French. But to the matter. Milk of the Fig tree will do the same, if it be written on white paper, and afterwards sent to a friend, be rubbed with coal dust strewn upon it, and made clean again, so will the letters presently appear black. Pliny says, the milk of Tithymals will to the like, to make the letters, and dust strewn on them to scower them. And thus women as he says, had rather speak with adulterers, then by letters. Ovid confirms this, admonishing maids in his Arte Amandi, how they may safely write to their sweethearts.
“Write with new Milk, it’s safe, unseen, but read
The writing with coaldust laid on full-right.
Moist flax will write as if that none had been,
And letters on your paper pass the sight.”
Also there is an art that one would not imagine, to write upon Crystal. For, being all transparent, no man will dream of it, and the letters lie hid within. Do it thus,
“That letters may appear upon Crystal by strewing on of fine dust.”
Dissolve Gum Arabick in water, or Gum Traganth, that it may be clear, and when it is well dissolved, it will not foul the Crystal, if you write upon it, or upon a cup or glass, for when the letters are dry, they are invisible. No man will imagine the fraud, if a cup be sent to prison, or a glass full of wine. When he would see the letters, rub burnt straw or paper on it, and the letters will presently be seen. Here is another secret,
“The letters on the paper may be read, not by fire, nor water, or any other thing, but in the dust only.”
This is a secret worth knowing. Dissolve Goat Suet with a little Turpentine. Rub the paper with this Liquor, and keep it. When you would send some news to your friend, lay on the paper smeared with the fat upon a letter you would send to your friend, write upon that win an Iron point, and the suit will make the characters on the letter. Send this away, and if it be intercepted, no water will make the words visible, or any other art, but only strewing dust upon it. Also you may make,
“That upon black paper, white letters may appear.”
The reason is this. Mingle the white and yolk of an Egg together, that it may be liquid as ink. With this Liquor, write on the paper what words you please, and dry them. When the paper is dry, make a black color over it, and dry it again, and send it. But that the letters may be visible, scrape the superficies of the paper with a broad Iron. For so it will be, that the ink being scraped off, where the letters were, they will appear white.