Modern curiosities of art & nature extracted out of the cabinets of the most eminent personages of the French court : together with the choicest secrets in mechanicks, communicated by the most approved artists of France
Lémery, Nicolas, 1645-1715.
An Ingenious way to Write so as it shall or shall not appear, or the double Letter.
Take a quarter of a pint of distill'd Vine∣gar, which put into a Vial, wherein must be half an ounce of Gold Litharge in fine Powder, stirring it from time to time, four or five times an hour, then let it stand twelve, fifteen, or twenty four hours, then pour off what's clear into another Vial by Inclination, and throw off the dregs, stopping the bottle close, and keep it against you would write white, or the double Letter, with the Ink that follows.
