It is NOT a branch of science.
It once was a study of how to transmute metals, for example, change other metals to gold. It was totally false, with no basis in science at all.
No one has seriously "studied" this for a long time.
wikipedia:
Alchemy, originally derived from the Ancient Greek word khemia (Χημία) meaning "art of transmuting metals", is both a philosophy and an ancient practice focused on the attempt to change base metals into gold, investigating the preparation of the "elixir of longevity", and achieving ultimate wisdom, involving the improvement of the alchemist as well as the making of several substances described as possessing unusual properties. The practical aspect of alchemy generated the basics of modern inorganic chemistry, namely concerning procedures, equipment and the identification and use of many current substances.
Alchemy has been practiced in Mesopotamia (comprising much of today's Iraq), Egypt, Persia (today's Iran), India, China, Japan, Korea and in Classical Greece and Rome, in the Post-Islamic Persia, and then in Europe up to the 20th century, in a complex network of schools and philosophical systems spanning at least 2500 years.
Alchemy encompasses several philosophical traditions spanning four millennia and three continents. These traditions' general penchant for cryptic and symbolic language makes it hard to trace their mutual influences and "genetic" relationships. Alchemy starts becoming much clearer in the 8th century with the works of the Persian Alchemist Jabir ibn Hayyan (known as "Geber" in Europe), who introduced a methodical and experimental approach to scientific research based in the laboratory, in contrast to the ancient Greek and Egyptian alchemists whose works were mainly allegorical.
Other famous alchemists include Rhazes, Avicenna and Imad ul-din in Persian alchemy; Wei Boyang in Chinese alchemy; and Nagarjuna in Indian alchemy; and Albertus Magnus and pseudo-Geber in European alchemy; as well as the anonymous author of the Mutus Liber, published in France in the late 17th century, which was a 'wordless book' that claimed to be a guide to making the philosopher's stone, using a series of 15 symbols and illustrations. The philosopher's stone was an object that was thought to be able to amplify one's power in alchemy and, if possible, grant the user ageless immortality, unless he fell victim to burnings or drowning; the common belief was that fire and water were the two greater elements that were implemented into the creation of the stone.
In the case of the Chinese and European alchemists, there was a difference between the two. The European alchemists tried to transmute lead into gold, and, no matter how futile or toxic the element, would continue trying until it was royally outlawed later into the century. The Chinese, however, paid no heed to the philosopher's stone or transmutation of lead to gold; they focused more on medicine for the greater good. During Enlightenment, these "elixirs" were a strong cure for sicknesses, unless it was a test medicine. In general, most tests were fatal, but stabilized elixirs served great purposes. On the other hand, the Persian alchemists were interested in alchemy for a variety of reasons, whether it was for the transmutation of metals or artificial creation of life, or for practical uses such as Persian Medicine.
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