Atramentum

[citation needed] In ancient Rome, the term atramentum signified any black colouring substance used for any purpose.

The word atrament is related to modern English atrocious: both originate from Latin atrare, which presumably meant to make something black.

In one modern commercial usage of the word, atramentum is a deep black colouring substance manufactured by a reaction of an iron salt with tannic acid (the tannic acid for this purpose is often extracted from oak bark).

It is currently a subject of conservation effort since many valuable collections are written using it but it causes ink corrosion.

[4][5] In Jewish tradition, scribes made use of iron sulfate (chalcanthum) in writing Torah scrolls, which caused the corrosion of the ink.