Abu Musa Jabir bin Hayyan (Geber) was one of the most notable Islamic alchemists. He was born 721 A.D in Tus (iran) and died 815 A.D (some say 803) in Kufah (present Iraq). He is credited with the discovery and description of many substances and processes, such as the Hydrochloric Acid and Nitric Acid, Distillation, and Crystallization, that have become the foundation of today's chemistry and chemical engineering. He was a prominent student of Imam Jafar Sadiq. Jabir bin Hayyan is considered the father of chemistry and he wrote more than two thousand books and treatises on different aspects of science and chemistry. The scientists of the modern world known him as "Geber", the greatest Muslim chemist and the forerunner of all those who have studied in the field of chemistry. He wrote innumerable books on medicine and related subjects such as health care, on minerals, metals, stones, geology, the science of geometry, etc. His book al-Jawhar is an original book on medical science which is still referred to by Western scientists as an original attempt at medical science. His last testament that he left for posterity is as follows:

Jabir bin Hayyan and Geber were also hin pen names of 14th century European alchemist, author of the treatise Summa Perfectione and several other books.

Jabir wrote more than one hundred treatises on various subjects, of which 22 are about alchemy. Firmly grounded on experimental observation, his books systematized the knowledge about the fundamental chemical processes of the alchemists, such as crystallization, distillation, calcination, sublimation and evaporation. Thus making a great step in the evolution of chemistry from an occultist art to a scientific discipline. In particular, Jabir emphasized that definite quantities of various substances are involved in a chemical reaction, thus anticipating by almost a thousand years the principles of quantitative chemistry and the law of constant proportions.

Jabir is also credited with the invention and development of several chemical instruments that are still used today, such as the alembic, which made distillation easy, safe, and efficient. By distilling various salts together with sulfuric acid, Jabir discovered hydrochloric acid (from salt) and nitric acid (from saltpeter). By combining the two, he invented aqua regia, one of the few substances that can dissolve gold. Besides its obvious applications to gold extraction and purification, this discovery would fuel the dreams and despair of alchemists for the next thousand years. He is also credited with the discovery of citric acid (the sour principle of lemons and other unripe fruits), acetic acid (from vinegar), and tartaric acid (from wine-making residues).

Jabir applied his chemical knowledge to the improvement of many manufacturing processes, such as the making of steel and other metals, rust prevention, gold lettering, cloth dyeing and waterproofing, leather tanning, and the chemical analysis of pigments and other substances. He developed the use of manganese dioxide in glassmaking, to counteract the green tinge produced by iron a process that is still used to this day. He noted that boiling wine released a flammable vapor, thus paving the way to Al-Razi's discovery of ethanol.

The seeds of the modern classification of elements into metals and non-metals could be seen in his chemical nomenclature. He proposed three categories: "spirits" which vaporize on heating, like camphor, arsenic and ammonium chloride, "metals", like gold, silver, lead, copper, iron; and "stones" that can be converted into powders.

In the Middle Ages, Jabir's treatises on chemistry were translated into Latin and became standard texts for European alchemists. These include the Kitab al-Kimya (titled "Book of the Composition of Alchemy" in Europe), translated by Robert of Chester; and the Kitab al-Sab'een by Gerard of Cremona (before 1187). Berthelot translated some his books known by the titles "Book of Kingdom", "Book of the Balances," "Book of Eastern Mercury," and it is obvious that he did not use correct titles for Jabir's books. Several technical terms introduced by Jabir, such as alkali, have found their way into various European languages and have become part of scientific vocabulary.

Jabir also made important contributions to medicine, astronomy, and other sciences. Unfortunately, only a few of his books have been edited and published, and fewer still are available in translation.