ماءِ الزَّاجِ / لَبَناً / ماءِ العَفْصِ

Ingredients

لَبَناً, ماءِ الزَّاجِ [الأَبْيَض], العَفْصُ المَدْقُوقُ, ماءِ العَفْصِ, وَشْقٍ, رَماداً حاراً

Preparation Steps

Original Recipe Text

Method 1: Write on paper with milk (laban). To reveal the text, sprinkle hot ash from burnt paper over it (p. 151). Method 2: Write with white vitriol water (ma' al-zaj al-abyad). To reveal, sprinkle finely crushed gallnuts over the writing (p. 151). Method 3: Reverse of Method 2; write with gallnut water and reveal by sprinkling vitriol powder (p. 151). Method 4: Use ammoniacum (washq) for writing and reveal with hot ash (p. 151).

Evidence

"أَنْ تَأْخُذَ لَبَناً [حَلِيباً] فَتَكْتُبَ به في قِرْطاسٍ، فَيُذَرُّ المكتوبُ إليه عليه رَماداً حاراً... وإن كُتِبَ بماءِ الزَّاجِ [الأَبْيَض] وذُرَّ عليه العَفْصُ المَدْقُوقُ... أو بماءِ العَفْصِ، وذُرَّ عليه شيئاً من الزَّاجِ... فإنَّه يَظْهَرُ."

Remarks

These recipes describe invisible or 'secret' inks used for sensitive correspondence in the Abbasid bureaucracy. The chemical reaction between iron vitriol and the tannins in gallnuts creates a black iron-gallate complex instantaneously (p. 151).