alchemy Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Greek: χυμεία, ''khumeía'') is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practiced in China, India, the Muslim world, ...

, digestion is a process in which gentle heat is applied to a substance over a period of several weeks. This was traditionally performed by sealing a sample of the substance in a flask, and keeping the flask in fresh horse dung or sometimes in direct sunlight. Today, practitioners of alchemy use thermostat-controlled incubators.John Reid's Course on Practical Alchemy - II Chapter 2
(November 1, 2010) Digestion is considered one of the 12 core alchemical processes and is "ruled", or "dominated", by the

zodiac The zodiac is a belt-shaped region of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The pat ...

al sign of Leo.

References

Alchemical processes {{science-stub