Black coal writing (ḫaṭṭ al-jinn)

Ingredients

quenched coal (al-faḥm al-muṭfaʾ), filtered water

Preparation Steps

Original Recipe Text

The recipe involves writing with filtered water on a piece of wood (possibly sāʿida). The writing remains invisible until quenched and ground coal (al-faḥm al-muṭfaʾ) is poured over the surface, causing the script to appear black, mimicking carbon ink (midād) (p. 178).

Evidence

"If one writes with it on a plank of wood (?), it will not appear until quenched coal is poured onto it, and then the writing will appear black, as if it were written with [carbon] ink (midād)."

Remarks

This method is colloquially referred to as 'the jinns’ way of writing' (ḫaṭṭ al-jinn). It is categorized under invisible and wondrous writings in Chapter 18 (p. 178).