Muhammad ibn Umail lived most probably in the first half of the 10th century. Part of his life he spent in Egypt, and he might have been Egyptian. He wrote works which belong to the mystical-religious branch of alchemy. In the Hall ar-Rumuz presented here ibn Umail tries to describe his inner experience of the stone of the sages with the help of symbols and allegories. This volume was one of 12 separate books released as the Corpus Alchemicum Arabicum. Each was issued separately.