The Journey of Bitumen and Lime: From Ancient Babylon to Styria, From Construction and Agriculture to Modern Meat Science

The journey through the historical uses of bitumen and lime illustrates their profound impact on ancient construction, food preservation, and agriculture. From Babylon’s towering ziggurats to Roman aqueducts and the Catholic monastic traditions, these materials defined human advancement. This study not only traces their historical significance but also connects them to modern meat processing practices, showcasing the enduring relationship between ancient wisdom and contemporary food science. For similar articles, please visit the site Zeno Holisticus Index Page.

29 September 2024
Eben van Tonder
The Magnificent Ancient City of Babylon

Introduction

My journey began with studying the role of lime in agriculture, tracing its use as a crucial technology “housed” and dispersed globally by the Catholic Church through its network of monasteries. This study was part of my ongoing research into how ancient fertility goddesses, spirituality, and minerals intersect, as explored in my article on Ancient Fertility Goddesses, Mary, Spirituality, and the Link with Minerals. Another significant work, “Saint Boniface: Apostle to the Germans and His Influence on Monastic Agriculture and Food Preservation,” delves into how such knowledge was spread through monastic communities.

As I delved deeper into these transitions, I encountered the important role of bitumen in the construction of the ancient city of Babylon, realizing that this material was as pivotal to Babylonian architecture as lime was to later European construction. This research complements my reflections on transition moments, as discussed in Liminality: Navigating Life’s Transitions. It became evident that the development and application of bitumen were foundational in building Babylon, allowing the construction of structures that far exceeded anything built before, including the Tower of Babel. Without bitumen, these massive constructions would have been impossible.

This exploration led me to examine the chemistry and role of carbonates, something I have always been eager to investigate but never found the time until now. Today, I delve into the use of different carbonates in meat processing and how ancient practices inform modern applications, fulfilling a long-held desire to understand these interactions deeply.

Bitumen: Its Origins, Composition, and Role in Babylon

What is Bitumen? Bitumen is a naturally occurring, sticky, viscous form of petroleum. Dark, dense, and water-resistant, it functions as an adhesive and waterproofing agent, crucial for construction. Chemically, it consists of complex hydrocarbons, including asphaltenes, resins, and oils, giving it unique binding and waterproofing properties.

Formation and Occurrence: Bitumen forms over millions of years as organic matter breaks down under heat and pressure in sedimentary rock formations. In ancient Mesopotamia, bitumen seeps were prevalent, with natural deposits found around present-day Iraq, Iran, and Syria, especially along the Euphrates River and in the region around Hit (modern-day Iraq). In Europe, natural bitumen deposits are rare but exist in places like the Italian Apennines.

The Use of Bitumen in Babylon: The scale and architectural feats of Babylon, particularly under King Nebuchadnezzar II (605–562 BCE), were unprecedented. The bitumen acted as a crucial binding material in building projects, ensuring structural integrity and waterproofing. One of the most iconic structures was the ziggurat of Etemenanki, often associated with the Tower of Babel. Its massive height (reportedly reaching up to 91 meters or 300 feet) would have been unsustainable without bitumen’s adhesive and water-resistant properties.

Comparisons with Previous Cities: Compared to earlier cities such as Uruk and Eridu, Babylon’s use of bitumen allowed for larger, multi-story constructions and more sophisticated urban planning. This leap in architectural capability meant that Babylon was far more advanced than any prior city in the ancient world.

Chemical Reactions and Properties: Bitumen’s ability to bond with bricks and stones arises from its adhesive nature, forming a tight seal that prevents water infiltration. When heated, it becomes more pliable, allowing easy application. Its waterproofing properties were particularly crucial for structures built near water sources, such as the Euphrates River, where Babylon was located. (For more detail on the chemical composition, refer to Heinrich, E. (1982), Die Tempel und Heiligtümer im Alten Mesopotamien).

Bitumen, Asphalt, and Similar Substances

Bitumen and asphalt are closely related. Asphalt is a mixture containing bitumen, minerals, and fine aggregates. Naturally occurring asphalt deposits were used for construction, but as a material, asphalt is more refined. Ancient Mesopotamians primarily used raw bitumen, while today, asphalt is widely used in road construction. Bitumen’s formation, unlike lime, is restricted to regions with petroleum deposits, making it less available globally than lime.

Other Uses of Bitumen: Besides construction, bitumen was used for waterproofing boats, creating mastic for seals, and even as an embalming agent in ancient Egypt. The Romans applied bitumen for waterproofing aqueducts and baths, a testament to its versatile applications.

The Transition from Bitumen to Lime

As the Roman Empire expanded, lime began to replace bitumen in construction. Lime, produced by heating limestone, became more accessible and versatile. Unlike bitumen, lime could bond stones and bricks more effectively, providing greater structural stability. The invention of hydraulic lime, combining lime with volcanic ash, revolutionized Roman engineering, enabling underwater construction, which bitumen couldn’t achieve.

The transition from bitumen to lime was gradual but decisive. The ease of lime production and its superior strength made it the preferred choice for large-scale constructions like aqueducts, fortifications, and the Pantheon.

Lime’s Use in Agriculture and the Catholic Church’s Influence Lime also played a crucial role in agriculture as a soil conditioner, improving pH levels and aiding plant growth. In Styria, Austria, natural slaked lime deposits in the soil contributed to the region’s agricultural productivity. The Catholic Church, through its monasteries, disseminated knowledge about lime’s agricultural benefits across Europe.

For example, Saint Boniface’s monastic network emphasized agricultural advancement, as referenced in “Saint Boniface: Apostle to the Germans”.

Chemistry of Lime: From Ground to Slaked Lime

Production Process:

  1. Limestone (CaCO₃) is heated to produce quicklime (CaO).
  2. Hydrating quicklime creates slaked lime (Ca(OH)₂).

Let’s delve deeper into the chemistry.

Limestone and Calcium Carbonate (CaCO₃)

Limestone is primarily composed of calcium carbonate (CaCO₃), but it often contains impurities like clay, sand, or magnesium carbonate (MgCO₃). I am familiar with Calcium carbonate and its role in the food industry, which includes its role as an acidity regulator, an anti-caking agent, and a calcium supplement. In meat production, we use it as a firming agent or in products like sausages for pH regulation.

Heating Phase: Formation of Quicklime (CaO)

When limestone (CaCO₃) is heated, it decomposes into quicklime (CaO) and carbon dioxide (CO₂):

In this reaction, one molecule of CO₂ is liberated because the carbonate (CO₃) unit splits, releasing one CO₂ gas, and the oxygen (O) remains bonded to calcium (Ca) to form CaO. The reason one molecule of CO₂ is liberated during the decomposition of CaCO₃ is due to the energy dynamics and bond strengths involved. Calcium carbonate (CaCO₃) consists of a calcium ion (Ca²⁺) and a carbonate ion (CO₃²⁻). When heated, the carbonate ion undergoes thermal decomposition. The C=O (carbon-oxygen double bonds) are generally stronger than C-O single bonds within the carbonate structure, but the decomposition is energetically favourable in releasing one CO₂ molecule because breaking the Ca–O bond requires less energy compared to the total energy released by forming CaO and CO₂.

The remaining single oxygen atom then bonds with calcium to form CaO, a more stable configuration. Thus, the process favours the release of one CO₂ molecule. This reaction exemplifies how bond strengths and energy considerations dictate chemical transformations.

The Importance of Carbonates

Carbonates (CO₃²⁻) are essential in natural processes, being the conjugate base of carbonic acid (H₂CO₃). They naturally form when CO₂ dissolves in water and reacts with bases, producing salts like calcium carbonate (CaCO₃). Sodium carbonate (Na₂CO₃) and other metal carbonates such as magnesium (MgCO₃) and potassium carbonate (K₂CO₃) have different solubility and chemical properties.

Acid-Base Nature:

  • Ca (Calcium) acts as the base component, while CO₃²⁻ is the acidic part.
  • This makes CaCO₃ technically a salt.

I list some of the common metal carbonates and some of their usages.

  1. Calcium Carbonate (CaCO₃):
    • Natural Occurrence: Found as limestone, chalk, and marble.
    • Uses: Building material (marble), agricultural lime, and as a dietary calcium supplement.
    • Ancient Name: Known as “calcite” or “limestone.”
  2. Sodium Carbonate (Na₂CO₃):
    • Natural Occurrence: Found as trona mineral or natron (historically used by Egyptians).
    • Uses: Glassmaking, soap production, and as a cleaning agent.
    • Ancient Use: Key ingredient in mummification and glass production.
  3. Magnesium Carbonate (MgCO₃):
    • Natural Occurrence: Found as magnesite mineral.
    • Uses: As a drying agent in sports, antacids, and in fireproofing.
    • Ancient Name: Known as “magnesia alba” or “white magnesia.”
  4. Potassium Carbonate (K₂CO₃):
    • Natural Occurrence: Rare in nature but obtained from wood ash.
    • Uses: Soap making, glassmaking, and as a drying agent.
    • Ancient Use: Referred to as “potash.”
  5. Copper Carbonate (CuCO₃):
    • Natural Occurrence: Found as the mineral malachite or azurite.
    • Uses: As a pigment and in early metal smelting.
    • Ancient Use: Used for green pigments in art.
  6. Iron Carbonate (FeCO₃):
    • Natural Occurrence: Found as siderite mineral.
    • Uses: Source of iron and in steelmaking.
    • Ancient Name: Known as “sideros.”

These carbonates were crucial in ancient metallurgy, medicine, and as building materials. They were known by various names and were key to many industrial and household processes in antiquity.

Hydration of Quicklime to Form Slaked Lime (Ca(OH)₂)

When quicklime (CaO) is combined with water, it undergoes an exothermic reaction to form slaked lime (Ca(OH)₂):

Slaked lime is softer, less caustic, and widely used in construction, agriculture, water purification, and in meat processing for hair removal during hide processing.

This process enhances lime’s binding properties, making it ideal for construction, agriculture, and even food preservation, including meat curing. The versatility of lime extended to soap and candle making, and it was used as an antimicrobial agent, making it valuable in food storage.

From Carbonates to Hydroxides

You noticed that when we go from Lime (CaCO₃) to Quick Lime (CaCO), the carbonate nature of the molecule is lost. Then, when we go from Quick Lime (CaO) to Slake Like (Ca(OH)₂), nit now changes into a Hydroxide. The changes are important from a functional perspective.

Carbonates in Meat Processing

Carbonates such as sodium carbonate (Na₂CO₃) and potassium carbonate (K₂CO₃) are crucial in meat processing by raising the pH, enhancing water retention, and improving emulsification. This adjustment makes proteins swell, allowing better water-binding and resulting in a juicier product. Calcium carbonate (CaCO₃), although less effective in water-binding compared to other carbonates, contributes significantly to the texture of emulsified products like sausages by interacting with myofibrillar proteins.

CaCO₃ slightly raises the pH, reducing electrostatic forces and causing myofibrillar proteins, primarily myosin, to unfold. This unfolding exposes hydrophobic sites on the proteins, which then bind more effectively with one another and with fat droplets. The result is the formation of a stable gel network that traps water and fat, giving the emulsion a firmer and more cohesive texture. This leads to improved product stability and a desirable bite in products such as sausages and other emulsified meat formulations.

The main reason for this lies in the solubility of the different substances.

Calcium carbonate (CaCO₃) is only slightly soluble in water compared to sodium carbonate (Na₂CO₃) and potassium carbonate (K₂CO₃), making its pH-raising effect more gradual and less pronounced. In contrast, Na₂CO₃ and K₂CO₃ are highly soluble, rapidly dissociating into their respective ions (Na⁺, K⁺, and CO₃²⁻), causing a more immediate and significant pH shift in meat emulsions.

CaCO₃ makes meat emulsions firmer which the sodium and potassium varieties don’t have. CaCO₃’s contribution to protein matrix stabilization is primarily due to the Ca²⁺ ions, which actively participate in cross-linking myofibrillar proteins. This cross-linking strengthens the protein network, enhancing the firmness and texture of emulsified products. The divalent nature of Ca²⁺ is the mechanism behind this. When we say that Ca²⁺ has a divalent nature, we mean it has a +2 charge, enabling it to form ionic bridges between two negatively charged sites (such as carboxyl groups) on different protein molecules. Compare the different charges again: Na⁺, K⁺, and CO₃²⁻. These ionic bridges act like “glue,” holding the protein chains together and reinforcing the overall structure. This cross-linking increases the stability and strength of the protein matrix, leading to a firmer texture in emulsified meat products like sausages, as the proteins are more tightly bound compared to the effects of monovalent ions like Na⁺ or K⁺.

In contrast, Na⁺ and K⁺ are monovalent ions that do not have the same capability to form these cross-links, resulting in less structural stabilization. Additionally, CaCO₃’s gradual pH-raising effect means it doesn’t cause significant protein unfolding or repulsion, allowing it to create a firmer, cohesive texture without disrupting the emulsion matrix excessively.

In addition to the above Ca²⁺ plays an essential role in the natural structure and function of proteins, particularly in maintaining the stability of muscle tissue and cellular structures. This natural affinity allows Ca²⁺ from CaCO₃ to integrate effectively within meat emulsions, contributing to protein stabilization, unlike Na⁺ and K⁺, which mainly modify ionic strength and charge balance without forming structural linkages.

Ancient Uses of Carbonates and Hydroxides and Its Current Status

In ancient Rome and Egypt, lime (CaCO₃) played a significant role in meat preservation and hide curing. Peter Garnsey in Food and Society in Classical Antiquity mentions, “lime was commonly rubbed into meat to deter bacterial growth and to dry it out,” providing an alkaline environment that prevented spoilage. Before consumption, the residue was rinsed off or neutralized with vinegar, ensuring the meat’s safety.

A. Lucas and J.R. Harris in Ancient Egyptian Materials and Industries noted lime’s role in hide processing: “The strong alkalinity of lime disrupted the protein bonds, aiding in the removal of hair and flesh,” a practice dating back to at least 2000 BCE.

R.J. Forbes in Studies in Ancient Technology confirmed its use for meat preservation, stating, “Lime’s antimicrobial properties were harnessed not only in hide curing but also in maintaining meat quality.”

Current Standing of Lime in Meat Preservation

United States (US): According to the USDA, calcium carbonate is approved for limited use in meat processing, mainly as a firming and anti-caking agent but not as a primary preservative.

European Union (EU): The EU allows calcium carbonate (E170) in meat processing but restricts its role mainly to pH regulation and as a filler.

Australia: Similar to the US and EU, Australia permits calcium carbonate in meat products but only as a food additive with specific functions.

Codex Alimentarius: Recognizes calcium carbonate as a food additive (INS 170) under the General Standard for Food Additives (GSFA), but its application in meat is limited mainly to texture enhancement rather than preservation.

These regulations show a shift from ancient preservation practices to modern, controlled use, where lime’s role is now more defined by regulatory standards than by direct preservation.

The Use of Lime in Styria and Graz

The use of lime (CaCO₃) in Styria, especially around Graz, has deep roots, particularly within the Catholic monastic traditions. Monasteries were instrumental in teaching lime’s applications in building, agriculture, and even in food preservation. According to Smith, N. (1996) in The Archaeology of Buildings, “monks in Graz not only used lime for constructing monastic structures but also employed it extensively to improve soil fertility, especially in the mountainous regions of Styria where lime was naturally abundant.”

Slaked Lime in Styria: It’s noteworthy that slaked lime (Ca(OH)₂) occurs naturally in Styria’s mountainous soils due to the limestone deposits present. This abundance made it easier for local communities to access and use it, not only in construction but also in agricultural practices to neutralize acidic soils, providing a clear advantage for crop production.

Historical Use of Lime in Meat Preservation in Hallstatt

The ancient curing pits discovered in Hallstatt, used for preserving pork on an industrial scale as early as 1200 BCE, indicate advanced knowledge of meat preservation. Although there is no direct evidence linking the addition of lime or slaked lime to these pits, it is plausible that the alkaline properties of lime could have aided in controlling microbial activity and preserving the meat. Lime’s ability to absorb moisture and create an inhospitable environment for spoilage organisms could have helped maintain meat quality while deamination occurred. This deamination process would release ammonia, which aerobic bacteria would convert to nitrites during curing, possibly accelerating the formation of natural curing agents in the meat hung in mine tunnels.

Potential Roman Influence in Styria: When the Romans arrived in Styria, they brought advanced knowledge of lime processing, possibly reinforcing or expanding existing practices. However, the use of lime in meat preservation could have already been known to the Styrians, given their early expertise in curing meat in Hallstatt.

Conclusion

Bitumen was fundamental in constructing Babylon and other Mesopotamian cities, enabling architectural marvels like the ziggurats and the grand walls of the city. Its waterproofing and adhesive qualities made it indispensable in the harsh Mesopotamian environment. However, as civilizations evolved, lime emerged as the superior material due to its versatility, strength, and availability. The Romans perfected lime usage, and through the Catholic Church’s monastic networks, this knowledge spread, influencing construction, agriculture, and food preservation techniques across Europe. These transitions reflect not just technological advancements but the evolving relationship between humans, their environment, and the materials they used to build their worlds.

References

  1. Childe, V. G. (1956). The Urban Revolution. The Town Planning Review, 21(1), 3-17.
  2. Heinrich, E. (1982). Die Tempel und Heiligtümer im Alten Mesopotamien. Walter de Gruyter.
  3. Holland, T. A. (1976). The Use of Bitumen in Mesopotamian Architecture. Iraq, 38(2), 113-119.
  4. Oates, J. (1986). Babylon. Thames & Hudson.
  5. Lucas, A., & Harris, J. R. (1962). Ancient Egyptian Materials and Industries. Edward Arnold.
  6. Vitruvius. (c. 30-15 BCE). De Architectura (On Architecture). Translated by Morgan, M. H. (1914). Harvard University Press.
  7. Oleson, J. P. (1984). Greek and Roman Hydraulic Technology: The History of Water Management. BRILL.
  8. Forbes, R. J. (1964). Studies in Ancient Technology, Vol. VI. Brill Academic Publishers.
  9. Smith, N. (1996). The Archaeology of Buildings. Routledge.
  10. Thayer, Samuel. (2006). The Forager’s Harvest: A Guide to Identifying, Harvesting, and Preparing Edible Wild Plants.
  11. Garnsey, Peter (1999). Food and Society in Classical Antiquity. Cambridge University Press.
  12. Pöllath, N. & Schmid, E. (2009). Hallstatt Culture and the History of Curing Meat. European Journal of Archaeology, 12(3).
  13. Green, M. J. (1992). The Druids. Thames and Hudson.
  14. The Acorn: Our Early Ancestors’ Staple Food. Journal of Ethnobiology and Ethnomedicine.