In a book. On a roll. Blot them out with the bitter water. Rather, "wash them off into the bitter water," in order to transfer the venom of the curses to the water. ἐξαλείψει … εἰς τὸ ὔδωρ, Septuagint.
The writing on the scroll was to be washed off in the vessel of water. Of course the only actual consequence was that the ink was mixed with the water, but in the imagination of the people, and to the frightened conscience of a guilty woman, the curses were also held in solution in the water of trial.
The direction was founded on a world-wide superstition, still prevalent in Africa, and indeed amongst most semi-barbarous peoples. In the ‘Romance of Setnan,' translated by Brugsch. Bey, the scene of which is laid in the time of Rameses the Great, a magical formula written on a papyrus leaf is dissolved in water, and drunk with the effect of imparting all its secrets to him that drinks it.
So in the present day, by a similar superstition, do sick Mahomedans swallow texts of the Koran; and so in the middle ages the canonized Archbishop Edmund Rich on his death-bed washed a crucifix in water and drank it, saying, "Ye shall drink water from the wells of salvation."