"As the results of discussions of long years held at my own house which is known as de Secreti, and into which none can enter unless he claim to be an inventor of new discoveries." Two of these treatises which were extant in the first half of the seventeenth century, dated respectively 1481 and 1483, dwell at great length on SECRET inks and specifically mention as translated into the English of the time "sowre galls in white wine," and "vitriol;" repeating Italian formulas pertaining to the "Secreta" of the twelfth century. About secret ink he tells us: "There are many and almost infinite ways to write things of necessity, that the Characters shall not be seen, unless you dip them into waters, or put them near the fire, or rub them with dust, or smeer them over. * * * * * * * * "Let Vitriol soak in Boyling water: when it is dissolved, strain it so long till the water grow clear: with that liquor write upon paper: when they are dry they are not seen. Moreover, grinde burnt straw and Vinegar: and what you will write in the spaces between the former lines, describe at large. Then boyl sowre Galls in white Wine, wet a spunge in the liquor: and when you have need, wipe it upon the paper gently, and wet the letters so long until the native black colour disappear, but the former colour, that was not seen, will be made apparent. Now I will show in what liquors paper must be soaked to make letters to be seen. As I said, Dissolve Vitriol in water: then powder Galls finely, and soak them in water: let them stay there twenty-four hours: filtre them through a linen cloth, or something else, that may make the water clear, and make letters upon the paper that you desire to have concealed: send it to your Friend absent: when you would have them appear, dip them in the first liquor, and the letters will presently be seen. * * * * * * * * If you write with the juice of Citrons, Oranges, Onyons, or almost any sharp things, if you make it hot at the fire, their acrimony is presently discovered: for they are undigested juices, whereas they are detected by the heat of the fire, and then they show forth those colours that they would show if they were ripe. If you write with a sowre Grape that would be black, or with Cervices; when you hold them to the fire they are concocted, and will give the same colour they would in due time give upon the tree, when they were ripe. Juice of Cherries, added to Calamus, will make a green: to sow- bread a red: so divers juices of Fruits will show divers colours by the fire. By these means Maids sending and receiving love-letters, escape from those that have charge of them. There is also a kind of Salt called Ammoniac: this powdered and mingled with water, will write white letters, and can hardly be distinguished from the paper, but hold them to the fire, and they will shew black."