V.I.T.R.I.O.L.
Presented as an ancient formula, it is first attested in print only in the early seventeenth century. It was later adopted into Masonic 'chamber of reflection' initiation ritual, which is how most people encounter it today.
The Basil Valentine corpus, Azoth (1613), earliest printed attestation of the acrostic
An alchemical acrostic instructing the seeker to visit the interior of the earth and, by rectifying, find the hidden stone.