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Volume 35, Number 6November/December 1984

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Bitumen - A History

Written by Zayn Bilkadi
Illustrated by Michael Grimsdale

The Sumerians called it esir, the Akkadians iddu, and the Arabs of Iraq sayali or zift or qar, but in English, it is simply "bitumen" or "asphalt" - that thick dark liquid you instantly associate with the smell of freshly laid pavement, and the first petroleum product ever used by the human race.

For thousands of years before the first civilization in Sumer, the substance we call bitumen was already prized as an adhesive - the result, apparently, of an ancient hunter's discovery that he could attach his flint arrowhead to a shaft with a sticky black substance found in a nearby spring. Several millennia later, that same substance cemented one of the wonders of the ancient world, a man-made mountain built to "rival heaven" - the famous Tower of Babel (See Aramco World, January-February 1967). In Egypt, it was used to preserve mummies, and many millennia later, with the coming of Islam, Muslim physicians began to prescribe it for skin ailments and wounds.

In ancient times, bitumen was primarily a Mesopotamian monopoly. To be sure, there were other areas in the Middle East where bitumen deposits had been exploited since early times: along the eastern shores of the Dead Sea and in Persia. But in neither Palestine nor Persia did this exploitation compare with that in Mesopotamia. For one thing, the "land between the rivers" was blessed, like no other land, with all sorts of petroleum deposits. From north to south along the Tigris and Euphrates rivers, the country was littered with bitumen seepages, crude oil springs and even bituminous rock which released crude oil when heated.

This oil, however, was not held in high esteem by the Mesopotamians; they did not know how to handle its flammability nor thicken it with evaporation. This led the Akkadians to invent the word naptu (forerunner of napht or naft in Arabic) to designate the supposedly useless flammable crude oil, as opposed to the highly prized iddu.

Later, with the coming of the Greeks and Muslims, naft would capture the scientific imaginations of the period; but initially, iddu was the only important petroleum substance, especially in the areas surrounding the ancient cities of Hit and Ramadi, on the south bank of the Euphrates (See map), where, from several hundred natural springs, pure bitumen oozed to the surface. This was the best bitumen, for it came out softened with occluded water, practically ready for use. The place called Hit, in fact, was synonymous with bitumen; iddu literally meant "the product from Id," and "Id" was the Akkadian name for Hit.

So important were the bitumen deposits of Hit to the Babylonian and Assyrian kingdoms that the city itself acquired a sacred character. A passage in the annals of King Tukulti Ninurta II (890-884 B.C.) reads: "In front of Hit, by the bitumen springs, the place of the Usmeta stones, in which the gods speak, I spent the night."

The "Usmeta" stones were gypsum deposits impregnated with bitumen and sulfur from which gases were expelled through crevices. This resulted in a muffled noise - assumed to be the oracular muttering of the underworld gods.

Actually, neither the Babylonians nor even their Sumerian predecessors were the first to use bitumen. Prehistoric hunting and farming communities used sickles made of flint arrowheads attached to a shaft with bitumen and made broken ostrich eggs into vases decorated with lapis lazuli and mother-of-pearl set in bitumen. But the people that first used bitumen on a large scale were the early settlers along the river in southern Mesopotamia: the 'Ubaids. At first marsh dwellers living in crude shelters, the 'Ubaids eventually came to be able and enterprising farmers, who prospered and multiplied over the centuries and built the foundations of most of the settlements along the Tigris and Euphrates rivers where the great cities of Sumer were later to grow.

The creative genius of these people emerged early - about 4500 B.C. - as they adapted to their harsh marshy environment. In a land barren of trees and without any stone quarries, they built astounding shelters of the only material available: fragile marsh reeds (See Aramco World, November-December 1966, March-April 1982) - bundling the reeds together with bulrush fiber, constructing frameworks of reed columns, roofing the structure with reed matting and, at first, insulating the interiors by plastering the walls with a thick layer of mud.

Since mud, however, could not resist the frequent spring floods, the discovery of bitumen was a distinct advantage: impervious to moisture and maintenance-free, it was a blessing to a community where mere survival was a daily dawn-to-dusk battle.

After that discovery, the 'Ubaids soon made another: how to waterproof their boats. By 4000 B.C., the 'Ubaids were already roaming the marshes of Shatt al-Arab in paddle boats of plaited reed, covered with stretched animal hides. But when they discovered the waterproofing properties of bitumen, they quickly began to coat the boats on the inside and outside, sealing the craft's hulls and reinforcing their fragile reed frames.

This technique was inherited almost unchanged by the Akkadians and Babylonians - as Herodotus, the first historian to visit Babylon, reported in astonishment. They use, he said, "curious small round boats woven together of reeds, like baskets, and waterproofed with a coating of bitumen." To this day, the circular guffah constructed of woven reeds caulked with bitumen are used to ferry passengers and merchandise across the Tigris River at Baghdad and the Euphrates River at Babylon.

In such craft the 'Ubaid seamen also ventured into the Arabian Gulf, eventually going as far as "Dilmun" in Bahrain - and the eastern coast of Saudi Arabia - to become the first documented seafarers of history.

In the alluvial plains to the north, meanwhile, ancient builders had reached for another raw material - clay - to mold the first building bricks. Initially, they just left them in the sun to dry - the kiln had not yet been invented - and began to lay the foundations of what were to become, under the Sumerians, mankind's first cities, first temples and first palaces.

After experimenting, however, the builders learned that sun-dried bricks by themselves were not strong enough to support large structures, so they began to add a little chopped straw to the clay before they dried it. These new bricks were a bit stronger, but since they would still collapse in a flood, or under prolonged rain, the builders eventually began to add bitumen too. When this happened is not known with certainty, but a good guess would be in prehistoric times, long before 3000 B.C.

What is known is that by the third millennium B.C., the Sumerians had improved the shape of the bricks - loaf-shaped at first - by making them flat on one side and convex on the other. More importantly, they also invented the kiln to harden the bricks. Now harder and waterproof, the bricks were also porous, and absorbed some of the bitumen used as mortar and became strong as rock. Esir was then mixed with straw or clay to make it into a stiff mortar capable of sustaining the heavy load of the superimposed brickwork without sagging. Thus were built, until 2200 B.C., the palaces and temples of distant Sumerian kings in such ancient cities as Kish, Ur and Uruk.

Even the planoconvex bricks, however, were not ideally shaped; their edges, still too irregular, required too much bitumen between the joints - three to six centimeters to be exact (one to two inches) - and bitumen was expensive. Thus came the last breakthrough, molding bricks in wooden frames, and the stage was set for the structures that were to dominate the Mesopotamian landscape: the lofty ziggurats, the dams and the fabulous palaces.

In the beginning, the largest of these structures were the ziggurats, massive stepped structures erected at the center of the city to lure the favors of various deities. With time, every city had its own ziggurat, and many of these grew to colossal sizes requiring millions of bricks and thousands of tons of bitumen.

Among the most famous of these structures was the Tower of Babel, which took hundreds of years to complete. Herodotus, who saw it standing shortly before its destruction, described it as a splendid seven-stage pyramid soaring 90 meters (295 feet) above the roofs of Babylon, each of its facades a different color and its baked bricks cemented with bitumen.

The Tower of Babel was completed by Nebuchadnezzar II, the last great king of Babylon, and one of the most prodigious builders in history. To Nebuchadnezzar, bitumen was a daily symbol of progress and prosperity, visible not only in the tower that he cherished, but in every paved street, wall, bath, bridge and drain pipe his workers touched. Among his achievements was a bridge over the Euphrates 120 meters long (393 feet), erected on piers of burnt bricks cemented and coated with bitumen. He also constructed large sewers lined with a mixture of bitumen, clay and gravel. He laid down the first paved streets by setting stone slabs in bitumen-mortar.

Nebuchadnezzar then began to build his palace - a symbol of the might and wealth of a city and the subject, on one of his tablets, of an eloquent description:

In Babel, my favorite city that I love, was the palace, the house, the marvel of mankind, the center of the land, the dwelling of majesty ... In consequence of high waters, its foundation had become weak, and owing to the filling up of the streets of Babel, the gateway to that palace had become too low. I tore down its walls of dried brick, and laid its cornerstone bare, and reached the depth of the waters. Facing the water, I laid its foundation firmly and raised it mountain high with bitumen and burnt brick. Mightly cedars I caused to be laid down at length for its roofing.. .For protection, I built two massive walls of asphalt and brick, 490 ells [English linear measure equal to 114 centimeters (45 inches)] beyond Nimitti-Bel [the outer wall of Babel]. Between them I erected a structure of bricks on which I built my kingly dwelling of asphalt and bricks. This I surrounded with a massive wall of asphalt and burnt bricks.

North of Babylon, meanwhile, the Assyrians, with access to stone, did not need bricks - but did use bitumen as mortar. One of the inscriptions of the Assyrian King Sennacherib (704-681 B.C.) describes his efforts to reclaim land by damming the river:

[I] covered the bed of the diverted river Telbiti with rush matting at the bottom and quarried stone on top, cemented together with bitumen. I thus had a stretch of land 454 ells long and 289 ells wide, raised out of the water and changed into dry land.

Curiously, bitumen was also important in early artistic expression during the development of civilization in Mesopotamia. In the 'Ubaid period, for example, bitumen was molded into wigs and covered with gold foil or copper to adorn terracotta figurines and larger stone statues. It was also used as a base in which to inlay precious stones for vases. And from the Royal Cemetery at Ur, you can see the extent of Sumerian artistic design and craftsmanship in such treasures as the "Standard," a two-sided panel in which small mother-of-pearl figurines are inlaid in bitumen with a mosaic background of lapis lazuli.

This inlay technique was also used to decorate figures in the round - such as a wooden harp with a gold bull's head and a standing goat; the head and legs of the goat, as well as the thicket on which he is leaning, are carved out of wood and covered with gold foil, cemented with bitumen. The back and flanks of the animal were also coated with bitumen in which hair had been embedded, and hundreds of other objects unearthed by archeologists in recent decades provide examples of bitumen in Mesopotamian art.

In Egypt, meanwhile, iddu had been largely ignored - and with good reason; Egyptian pyramids, after all, were built of massive cut stone, not the crumbly mudbricks of the ziggurats, and Egyptian ships were constructed with papyrus, a natural fiber far more buoyant and resistant to salt water than the burdi reed of the Mesopotamian ma-gur (See Aramco World, November-December 1980). The Egyptians, in short, were never as preoccupied with waterproofing as the mudbrick masons, the reed-bundle architects and the curved-reed shipwrights of the Euphrates. Since the raw materials were different, so were the needs.

And yet, sometime around the middle of the fourth century B.C., the Egyptians began to search frantically for a new source of bitumen. They found such a source in the Dead Sea - which the Greek historian Diodorus Siculus described in detail about A.D. 50:

It is a large sea which yields up much asphalt and from which a by no means negligible revenue is derived. The sea is about 500 stadia (90 kilometers) in length and 60 stadia (12 kilometers) wide. The water stinks and is exceedingly bitter so that fish cannot live in it. Every year a large quantity of asphalt in pieces over three plathrae (100 meters) float in the middle of the sea. The advent of asphalt is heralded 20 days before its arrival, for all around the sea the stench is wafted by the wind over many stadia and all the silver, gold and copper in the neighborhood becomes tarnished.

To collect the floating bitumen from the Dead Sea was by no means difficult; as Diodorus Siculus said, "Those who make it their business to collect bitumen simply draw one end into their boats and the rest of the mass follows." But it was the Nabateans, whose kingdom stretched between the borders of Syria and Arabia, down to the Red Sea, who owned the bitumen. Indeed, the Nabatean kingdom, one of the great kingdoms of the ancient world, owed its prosperity to two monopolies: the rich caravan trade that passed from the interior of Arabia to the coast, and the bitumen trade from the Dead Sea. And since the Nabateans charged a hefty price, fully aware that they had a captive market, Egypt had troubles.

The reason for Egypt's sudden need for bitumen was, according to Diodorus Siculus, mummification. "The largest portion of the asphalt derived from the Dead Sea is exported to Egypt, where among other uses, it is employed to mummify dead bodies, for without the mixture of this substance with other aromatics, it would be difficult for them to preserve these for a long time from the corruption to which they are liable."

Mummification had been going on for a long time before 400 B.C., of course, but about 350 B.C., the Egyptians began to run short of the resins they had relied upon in the past to embalm the bodies of their dead. They somehow discovered that bitumen could provide a good substitute, but having no bitumen deposits themselves, had to accept Nabatean terms since to them, embalming, an assurance of eternal life, was vital.

About the same time, unfortunately, the Macedonians, arch-enemies of the Ptolemaic Egyptians, also needed the Dead Sea bitumen, and about 312 B.C., 10 years after the death of Alexander the Great, Antigonus the One-Eyed, ruler of Phrygia and one of the most ambitious of Alexander's successors, attacked Petra, the Nabatean rock fortress in today's Jordan.

What Antigonus hoped for was to cut Egypt off from the Dead Sea bitumen and thus lure her into a second front. But the attack failed, and the Nabateans resumed their exports to Egypt. Then Egypt, perhaps alerted by the attack to the possibility of losing their supplies of bitumen, also attacked the Nabateans and temporarily won control of the east coast of the Dead Sea, and its bitumen.

Some 240 years later, after the Nabateans had retaken the Dead Sea, the Roman Empire got into the act - when Antony seized the sea and gave it as a gift to Cleopatra. By then, however, mummification was no longer fashionable and both the bitumen and the Dead Sea lost their value for the next 12 centuries.

In the ensuing eras, the use of bitumen was apparently restricted to localities where it was found: Hit, al-Ramadi and Kirkuk in Iraq, Bandar Abbas and Bushir in Iran, Benaid el-Qar in Kuwait and areas on the island of Bahrain. During this time, as in ancient times, the primary use was probably as a mortar in construction and as a waterproofing agent in boats. By the time of the Prophet, however, crude oil was being used as fuel near Susa in Iran and in various scattered localities in the northern mountains of Iraq, and the ninth century Muslim writer al-Jahiz claimed that the Arabs had been familiar with the military uses of petroleum as an incendiary substance since the year 600. This could be true since the inventor of "Greek fire," a highly combustible mixture petroleum, quick lime and sulfur, was from Syria.

It was the Byzantines, however, who first used "Greek fire" in open warfare; at the naval battle of Cyzicus in the year 675, the fleet of Constantine Pogonatus mounted double-action piston pumps in the prows of their warships and squirted the volatile mixture onto Muslim vessels. It was also used against the Arabs during their last siege of Constantinople in 717. The Arabs, however, soon learned the exact composition of the combustible mixture and used it themselves in Asia, where they transmitted it to the Chinese. Indeed, by the year 850 even crew members of Arab trading vessels in the Indian Ocean would use it to protect their ships against pirates, and during the reign of the Abbasid Caliph al-Mutawakkil each corps of archers in the infantry had a special division of naphtha-throwers called naffatun, who wore fireproof suits, perhaps of asbestos, and hurled "grenades" at the enemy by hand or with catapults. Some of the "grenades" were astoundingly similar in size and shape to those used in modern times: round iron - or clay - jars which contained the flammable mixture and exploded shortly after the lids were opened. What these advances in the military sciences tell us is that by the middle of the ninth century, Muslim forces were using large quantities of flammable petroleum products - at times more flammable than the heavy crude oils collected in Iraq and Iran. This was the result of an amazing technological breakthrough: distillation.

A primitive method of refining bitumen, probably of Babylonian origin, distillation, was well known to 'Ali ibn al-'Abbas al-Majusi in 950; he says that a hide was stretched over a kettle containing boiling bitumen so that liquid oil could be obtained by wringing the condensed liquid from the hide. But the Egyptian scientist al-Mas'udi, a contemporary of al-Majusi, also obtained an oily product from zift by a process reminiscent of modern cracking techniques. He used two superimposed jars separated by a screen or sieve. The upper jar, filled with bitumen, was heated with a fire, and the oily distillate allowed to drip through the screen into the bottom jar buried in damp sand.

Another method invented by the Muslims was an advanced distillation technique, called taqtir, in which they used a long glass column capped with a water-cooled condenser - the device being called al-anbiq (alembic). Exactly when the alembic was used for the first time cannot be said with certainty, but al-Razi himself was distilling olive oil in the alembic in 850.

So advanced a stage did petroleum refining reach under the scientists of Islam that in the early 12th century, kerosene or white naphtha could be purchased anywhere in the streets of Damascus. Indeed, a considerable distilling industry prospered in Damascus and, apparently, in Egypt too. In one account it was claimed that in one day a fire at the residency of the Fatimid ruler al-Mustansir destroyed 100 tons of refined naphtha.

By then, of course, the use of petroleum products was varied. In paving roads, for example, Muslim engineers, like the workers of Nebuchadnezzar, used a mixture of sand and bitumen that they called ghir in Iraq. In his book Aja'ib al-Buldan ("Wonders of the Lands"), the Arab cosmographer al-Qazwini tells us:

There are two kinds of ghir, first the kind that oozes from the mountains, and then the other kind that escapes with water in certain pools, it boils together with the water of the spring. As long as it remains in the water it is soft. If we separate it from the water it cools and dries. It is extracted by means of mats and thrown on the shore. Then it is put in a kettle which is heated, the adhering sand is mixed and more sand is added and stirred to a good mix. Afterwards, when the mix is ready it is poured on the floor and becomes solid and hard. Ships and bathrooms are also painted with this mix.

If we look at all the chemicals that man uses for his daily living in the 20th century, we are likely to find that they are in the vast majority derived from one single substance - petroleum. This is certainly true in modern agriculture, in medicine, and in the textile industry - where both the dyes and the fibers themselves are synthetics made from various treatments of crude oil. But some of these applications were already prefigured in the medieval Islamic era. To make a black dye for clothing and ink, for example, Muslim scientists burned bitumen or crudes, and collected the powdery soot. In Sicily, Spain and Syria, Muslim farmers burned bitumen with sulfur under trees or bushes to kill caterpillars and other harmful insects. And in medicine, Muslim physicians used petroleum and bitumen for pleurisy and dropsy - the patient was given "bitumenous water" to drink - and for various skin ailments and wounds. In Egypt, in particular, the bitumen and oil products used for medicinal purposes were called mumiya, which the physician Ibn al-Baitar described as:

the drug just mentioned and the bitumen of Palestine and mumiya of the tombs as found in great quantities in Egypt and which is nothing else but the mixture formerly used for embalming the dead, in order that their dead bodies might remain in the state in which they were buried and neither decay nor change.

Western Europe came to know mumiya, or bitumen, primarily from descriptions of its healing properties by 12th-century Muslim physicians in Egypt, but with the decline in scientific progress in the Middle East after the 12th century, the marvelous potentials of bitumen and naphtha were once again forgotten and were not to be rediscovered until the middle of the 19th century when the first modern oil well was drilled and petroleum became the very lifeblood of modern society

Zayn Bilkadi, a chemist, was born in Tunisia, attended the American University of Beirut and earned his Ph.D. at the University of California.

This article appeared on pages 2-9 of the November/December 1984 print edition of Saudi Aramco World.


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