De Verborum Significatu
Sextus Pompeius Festus
Muries est, quemadmodum Veranius docet, ea quae fit ex sali sordido, in pila pisato, et in ollam fictilem coniecto, ibique operto gypsatoque et in furno percocto; cui Virgines Vestales serra ferrea secto, et in seriam coniecto, quae est intus in aede Vestae in penu exteriore, aquam iugem, vel quamlibet, praeterquam quae per fistulas venit, addunt, atque ea demum in sacrificiis utuntur.
There is the salt-cake, just as Veranius teaches, that which is made from unrefined salt, crushed in a mortar, and put in a jar made of clay, and there covered with gypsum and cooked thoroughly in an oven; to this, after it has been cut with an iron saw, and put into a cylindrical earthen vessel, which is within, in the temple of Vesta in the outer sanctuary, the Vestal Virgins add ever-flowing water, even as much as they want, except that which comes through pipes, and at last they use it in sacrifices.
Translation by Jane W. Crawford, © 2001.