Alphitomancy was practiced using a loaf of barley bread. It was usually performed to prove the innocence or guilt of someone, particularly if several persons were suspected of a crime with no clearly guilty individual. All of the suspects were given the bread to eat, and it was assumed that those innocent would be able to eat it without difficulty, while the guilty person would get indigestion or choke. The practice became so prominent that eventually it was also used to test the faithfulness of a mistress, a husband, or a wife.
A quantity of pure barley was kneaded with milk and a little salt (and no yeast). This was rolled up in greased paper and baked among cinders. Once it was done, it was taken out and rubbed with verbena leaves. Pieces of it were given to the suspects to eat.