One important direct use of petroleum products (e.g. tar) was medicinal (Barnes and Grieve, 2017). Since most oils that had seeped to the surface would mostly evaporate and leave behind bitumen - the tarry component of the mixture of hydrocarbons from which it is composed, this tarry material was the most in use. Even in Ancient Europe, tar once had the reputation of being a panacea. Pine tar, a carbonized distilled form of pine, is reported to be in use for over 2000 years as a medicine for skin conditions because of its soothing and antiseptic properties (Barnes and Grieve, 2017). Although pine tar is considered to be distinct from coal tar or naturally occurring petroleum tar, they all have medicinal values for a wide range of applications because of its antipruritic, anti‐inflammatory, antibacterial and antifungal nature (Muller, 1984). In addition to its keratolytic action, pine tar has been shown to be antipruritic (Braun‐Falco, 1991), anti‐inflammatory, antiseptic (Dawber, 1994), astringent, keratoplastic, cytostatic, antibacterial (Veijola and Mustakallio, 1964) and antifungal (Ishida et al., 1992). This is no surprise because it is well known that tar from natural sources have all of the natural chemicals (including heavy metals) that can serve as a medicine. After all, the pharmaceutical industry indeed uses the synthetic version of the same chemicals.
Similarly, crude oil is known to have been used since the ancient era. Even today, some parts of the globe use crude oil for medicinal (Dienye et al., 2012) and therapeutical (Hoke, 2015) purposes. However, in the modern era, use of crude oil or petroleum products in their native form is not promoted as a valid material source for any application and invariably all petroleum resources undergo refining.
In terms of refining petroleum products, there is evidence that even during medieval era, refining techniques were present. However, those days, refining was not done in an unsustainable manner (Islam et al., 2010). There is evidence that both distillation and expression were common during the medieval era. In the perfume industry, as early as during early Islamic era (7th century onward), distillation in the form of hydrodistillation and production of absolute, mainly through Enfleurage and fermentation was common (Katz, 2012).
The distillation process for refining oil appears to have been practiced throughout ancient times. Recent discovery of a 5000-year-old earthenware distillation apparatus, used for steam distillation tells us that our ancestors were well versed on developing sustainable technologies (Shnaubelt, 2002). Khan and Islam (2016) demonstrated how an earthenware distillation apparatus is sustainable. The ancient and middle age practices were mainly focused on medicinal applications. It was the case in ancient Orient and ancient Greece and Rome, as well as the Americas the oils used for medicinal purposes.
However, as reported by Islam et al. (2010), Medieval era scientists were also refining oil for producing shoot-free light. During the fifth century AD, the famed writer, Zosimus of Panopolis, refers to the distilling of a divine water and panacea. Throughout the early Middle Ages and beyond, a basic form of distillation was known and was used primarily to prepare floral waters or distilled aromatic waters. These appear to have been used in perfumery, as digestive tonics, in cooking, and for trading.
Over 1000 years ago, Al-Rāzī (865-923), a Persian Muslim alchemist, wrote a book titled: Kitāb al-Asrār (Book of Secrets), in which he outlined a series of refining and material processing technologies (See Taylor, 2015 for the translation). Al-Rāzī developed a perfectly functioning distillation process. In this distillation process, he used naturally occurring chemicals. His stockroom was enriched with products of Persian mining and manufacturing, even with sal ammoniac, a Chinese discovery. These were all additives that he was using similar to the way catalysts are used today. His approach was fitting for his time, but way ahead of today’s concept of technology development. He avoided, the ‘intellectual approach’ (what has become known as mechanical approach ever since Newtonian era or New Science) in favour of causal or essential approach (what Khan and Islam, 2016, called the ‘science of intangibles’). Table 2.1 shows that the 389 procedures by Al-Rāzī can be divided into four basic types: primary, intermediate, reagent, and preparation methods. The 175 “primary” procedures involve transformation of metals into gold or silver. It is worth noting here that bulk of Newton’s unpublished work also involved transformation of metals into gold (Zatzman and Islam, 2007). The 127 preparatory procedures involve softening and calcination. Today, equivalent processes are called denaturing, in which the natural features of materials are rendered artificial. Al-Rāzī then adds 51 procedures for reagent preparations. The reagents are solvents and tinctures, which usually contain trace amount of heavy metals. It is similar to what is used today except that Al-Rāzī used natural sources. Table 2.1 further shows 36 instructions for commonly needed processes such as mixing or dissolving.
The procedure types include sublimation, calcination, softening whereas major sources are all natural (such as, quicksilver, sulfur, metals, stones). The calcination, sublimation and calcination themselves are also done through natural processes.
The dominant theme was all source materials are derived from plants, animals and minerals and used in their natural state. The knowledge of seven alchemical procedures and techniques involved: sublimation and condensation of mercury, precipitation of sulphur, and arsenic calcination of minerals (gold, silver, copper, lead, and iron), salts, glass, talc, shells, and waxing. In addition, the source of heat was fire.
Table 2.1 Classification of the procedures use by Al-Razi in Book of Secrets.
| Type of procedure | Purpose | Count | Percent | Example |
| Primary | Produces a substance that transforms metals into gold or silver | 175 | 45 | Sublimation of mercury |
| Intermediate | Prepares materials required for primary procedures | 127 | 33 | Calcination of silver through burning |
| Reagent | Produces a chemical used in other procedures | 51 | 13 | Liquids that dissolve or create colours |
| Preparation | Instructions for a method used in other procedures | 36 | 9 | Mixing through pulverizing and roasting |
| Total | 389 | 100 |
Al-Rāzī gave methods and procedures of coloring a silver object to imitate gold (gold leafing) and the reverse technique of removing its color back to silver. Also described was gilding and silvering of other metals (alum, calcium salts, iron, copper, and tutty, all being processed in a furnace with real fire), as well as how colors will last for years without tarnishing or changing.
Al-Rāzī classified naturally occurring earthly minerals into six divisions (Rashed, 1996):
I. Four spirits (Al-Arwāh, the plural of the Arabic word Rūh, which is best described in the Qur’an