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Abu Musa Jabir ibn Hayyan is one of the most prominent Muslim scientists of the early Islamic period. His name has been for many centuries synonymous with utmost authority in alchemy. Jabir was a Shia Muslim and he was disciple of the sixth Shia Imam, Imam Jafar al-Sadiq (as). He is responsible for a number of remarkable treatises in diverse scientific subjects.
Jabir regarded himself as just a spokesman of his teacher’s, Imam Jafar al-Sadiq (as), doctrines. He adopted the method of symbolic and hermeneutic interpretations of material which has been common among the Shia. The numerous works in Jabirian corpus, which according to Paul Kraus some of which include later works of Ismalis also, deal with nearly every subject. To name a few; cosmology, alchemy, astrology, and science of numbers.
“Jabir bin Hayyan is credited with the introduction of experimental methodology into alchemy and the invention of several chemical processes used in modern chemistry. These include crystallization, calcinations, sublimation and evaporation, the synthesis of acids (hydrochloric, nitric citric, acetic and tartaric acids), and distillation using his greatest invention, the alembic (anbaiq). Other achievements included preparation of various metals, development of steel, dyeing of cloth and tanning of leather, varnishing of waterproof cloth, use of manganese dioxide in glass-making, prevention of rusting, and identification of paints and greases. He also developed aqua regia to dissolve gold.” 
Jabir acknowledged the works of earlier scholars and alchemists and benefited from them. In this way, he truly regarded the acquisition of knowledge as an ongoing, continuous effort. In this way, he both benefitted from the earlier scholars’ works and adds his own contributions that would together benefit the future scholars. He says:
“Know that successive philosophers have enabled the science of alchemy to profit from a long development and have given it an extraordinary power, thus attaining their end. Arius [precursor of Hermes] was the first of those who devoted himself to this art; starting with him an uninterrupted tradition has come down to us, despite the distant epoch in which he lived.”
In today’s world of artificial intelligence and robotics, there is constant talk of imitating nature and making what nature produces. But not to our surprise, Jabir, a scientist beyond his times, mentions that it is possible:
“…(Arius) appeared and declared that the man possesses the ability to imitate the action of nature. He gave an example of this by reducing the things to their primitive nature. He melted metals and submitted them to perpetual coction, analogous to the perpetual and unchanging coction that nature uses.” 
The Jabarian method of alchemy is based upon the idea of balances by which correct proportion of elements is reached. As per him, all alchemical work involves the establishment of the correct proportion of qualities, namely; hot, cold, dry, and moist.
Jabir says: “…the principle of the art was determined solely by the occurrences of natures; it is by the weights or the balance, of the natures that one succeeds in knowing them.Therefore, he who knows their balance, understands all the ways in which they behave, and the manner in which they are composed.” 
The use of balance in alchemy implies the existence of correct proportions of the qualities in metals. According to Jabir, each metal has two exterior and two interior qualities. For example, gold is inwardly cold and dry, outwardly hot and humid; while the silver is just the reverse. Silver is hot and humid inwardly, cold and dry outwardly. Each quality has four degrees and seven sub divisions or altogether, 28 parts. According to Jabir everything in the world exists by the number 17, divided into the series 1:3:5:8. The opposing natures of the metals are in the ratio of either 1:3 or 5:8, or vice versa. 
The establishment of the equilibrium or balance of which Jabir speaks depends upon the reduction of elements to their natures, from which the correct proportion of the qualities can be harmonized according to the alchemical balance. Jabir divided materials with which alchemy deals into three classes: each having certain specific qualities based on the predominance of the one of the natures. Firstly, the “spirits” which become completely volatilized into fire. Secondly, the “metallic bodies” which can be hammered, possess a lustre, produce a sound and are not mute like the “spirits” and “bodies”. Lastly, the “bodies” [mineral substances] which cannot be hammered but can be pulverized. Moreover, the “spirits” are five in number: sulphur, arsenic, mercury, ammoniac, and camphor. The metals include: lead, tin, gold, silver, copper, iron, and kharsini (Chinese iron). 
In the above classification of the minerals, Jabir is referring to the substance in terms of physical aspects of the things. However, the key to understanding them lies in comprehending the balance of the qualities and in the harmony between the inner and outer aspects of the substances, and not in the physical aspects of them alone.
The modern theory of acid-base owes its concepts to the Jabir’s Sulfur-mercury theory of the constitution of the minerals. This theory of sulfur-mercury explains the active (masculine), and passive (feminine) duality upon which all cosmic existence depends.
Jabir laid a great emphasis on experimentation and practical applications. The following remark from him displays this fact:
“The first essential in chemistry is that thou shouldest perform practical work and conduct experiments, for he who performs not practical work nor makes experiments will never attain to the least degree of mastery. But thou, O my son, do thou experiment so that thou mayest acquire knowledge. Scientists delight not in abundance of material; they rejoice only in the excellence of their experimental methods.” 
1. Arab and Muslim Physicians and Scholars, Jabir ibn Hayyan, by Samir S. Amr, Abdelghani Tbakhi
2. Science & Civilization in Islam, Chapter: The Alchemical Tradition, by Seyyed Hossein Nasr
7. Makers of Chemistry, by Eric John Holmyard