The following is extracted from vol. 4, page 408, of the Encyclopédie de Diderot (1751-1780).
In order to prepare a liquor which will penetrate into the interior of Marble in such a manner that one can paint on the surface, designs which seem to be within the material, it is necessary to proceed in the following manner: Take of agua fortis and agua regia, each two ounces, one ounce of salts of ammonia, two drachms of the best spirits of wine, as much gold as can be bought for a hundred pence, and two drachmas of pure silver. When you are furnished with these materials and have calcined the silver, put it in a vial, and having poured upon it the two ounces of aqua fortis, leave it to evaporate; you will thus have a water which will at first give a blue color, and finally a black. Calcine the gold in the same manner, put it in the vial, and, pouring the aqua regia upon it, leave it to evaporate. Finally pour your spirits of wine upon the salts of ammonia, leaving it also to evaporate; you will thus have a golden colored water which will furnish different colors.
