10I have now to speak of those bodies which, from particular treatment, change their qualities, and acquire the properties of colours; and first, of black, which is much employed in different works, in order that it may be known how it is prepared for use.
2An apartment is built similar to a laconicum, plastered with marble stucco, and polished. In front of it is built a furnace, which communicates with the laconicum; the mouth of this is to be very carefully closed, for the purpose of preventing the escape of the flame. Resin is then placed in the furnace, whose smoke, when the material is set on fire, passes by means of communications into the laconicum, and therein adheres to the walls and the arched ceiling. It is then collected, and some part of it is tempered with gum, to make ink for transcribers; the remainder is used by stuccoers in colouring walls, being previously mixed with size.
3But if this cannot be procured, in order to prevent delay, the following expedient may be adopted. Pine branches or chips must be burnt, and, when thoroughly charred, pounded in a mortar with size. Thus the plasterer will procure an agreeable black colour.
4A black colour, not less pleasing, is made by drying and burning lees of wine in a furnace, and grinding the result with size. Indeed, this makes a very agreeable black. The better the wine whose lees are used, the better will be the black colour; which will, in such case, approach the colour of indigo.