17 July 2024
Eben van Tonder
Introduction
I have been looking into the origin of meat curing for many years now. I made several discoveries over the years. The curing agent that probably pre-dates the use of saltpetre (nitrate) in meat curing is sal ammoniac (ammonium chloride). Curing with saltpetre was most likely developed in and around the Turfan depression in the far western region of China. The discovery of curing was probably accidental when seafarers stored meat in seawater and surface proteins were deaminated, in other words, the proteins were broken down into amino acids and the amino acids were further broken down, thus creating ammonia which was oxidised by bacterial action to nitrites which then cured the meat. I knew that curing meat by the use of sweat from horses, for example, has been practised by nations resident to the regions of Mongolia and even the Boers in South Africa cured their biltong with horse sweat for a time at the beginning of their wholesale venturing into the interior of Southern Africa.
Still, I could not see how and why bitter potassium nitrate would have been used on meat. I have long been uncomfortable with the “accidental discovery” business. The “curing experiment” ‘s likelihood of success seemed low to me. With Richard Bosman, we have been working on an L-Arginine-based curing mechanism for some time now and despite successes, repeating the successes and forging it into a commercial system remains problematic.
When we talk about, for example, saltpetre from a historical perspective, we can not imagine a pure substance as we may be familiar with. Salt in antiquity was a fickle business at best and salts were majorly mixed with impurities, others salts and often simply wrongly classified altogether.
Here I present an alternative for the first time of how curing came about. Much work remains, but the evidence is sufficient to raise the strong suspicion that what I present may be closer to the truth than what I previously thought to be the origins of meat curing.
An Alternative Picture of Ancient History
It seems to me that people from antiquity became extremely skilled in managing human and animal excrement, both urine and droppings or manure. Its properties were understood for tens of thousands or you’re, possibly over 100 000 years. As with anything deer to humans, it was incorporated into our stores, our religion and our general cultural practices. We used in, or at least tried to use it, in everything from meat preservation to medicine.
Through careful observations of the natural world, humans realised that there is a link between urine and a salt that came to be known as saltpetre (a salt of nitrate) and a link between droppings and sal ammoniac (ammonium nitrate) was made in the human mind. We tried to work out what the link was, but mostly people did not concern themselves with the “why”. They were focused on the “how”. What started as a very tentative project, humans became better at creating nitrate salts from urine and dung and sal ammoniac from dung.
We incorporated both the original inspiration of dung and urine into the emerging system of alchemy. So strong were its presence and so absolute its domination in the ancient world that even when we got better at making saltpetre ourselves and sal ammoniac, not even these two salts could dethrone the position of permanence that dung and urine had in alchemy and the many religious practices that incorporated its use.
This picture emerged out of the preponderance of evidence I considered over the last 20 years in trying to understand the origins of the art of meat curing. What seems to have happened is that people would make pits in the ground to store their meat, just as they would place them in bodies of water to protect them from predators. We learned that such pits were constructed in clay soil that can hold moisture and if we add urine and dung and possibly salt and water to the pits before we cover it, that enigmatic forces which we know are reactions by chemistry, bacteria and enzymes in the meat, had the effect on the meat that on the one hand it cured it and on the other hand it fermented it.
I have little doubt that the curing vats discovered in Hallstatt dating back to 1200 BCE, stand in exactly this tradition. It gives us a glimpse of what was done on a private and small scale by the much larger and industrial application of the practices and procedures.
In the rest of this document, I will begin to bring together the matters I considered over the last 20 years and the specific events this week that led me to this conclusion.
Investigating the Use of Chicken or Goose Droppings in the Production of Ferrum Noricum
The particular study that caused me to re-evaluate every bit of information I have came to me when Christa Berger from Austria asked me to assist her in evaluating the use of chicken or goose droppings in the production of Ferrum Noricum. It was this work that brought me in close proximity with thoughts I had about the use of excrement and urine in antiquity. For starters, there were legends of the use of poultry droppings in iron smelting. The only possible use for this would have been its carbon and nitrogen content. Charcoal would have been a much better course of carbon and even as far as nitrogen is concerned, there would have been other options such as saltpeter.
In previous work I’ve done on sal ammoniac, I came across references which indicate that the ancients were well aware of the fact that nitrogen content could be manipulated in dung from humans and animals by altering their diets. Of course, they had no idea about nitrogen, but they were aware of the special properties they were looking for and they “calibrated” for it.
Aikin, A., & Aikin, C. R. (1807) discuss the use of animal dung for the production of sal ammoniac (ammonium chloride). They list the other possible animal parts that could be used over and above the dung namely horns, feathers, wool, soot, bones, blood and putrid urine. So, they make it clear that almost any part of the animal could be used for sal ammonia production. Still, they consider animal dung as the primary material.
An interesting observation from The New York Tribune quote of 31 January 1874 which I also quote in the article, From Sea to Deserts -> Sal Ammoniac Predating Saltpetre shows that the aninets worked out how to “concentrate” certain characteristics on dung. The dung of four-footed animals that feed only on vegetables “is fit to burn for sal ammoniac only during the four first months of the year when they feed on fresh spring grass, which, in Egypt is a kind of trefoil or clover; for when they feed only on dry meat, it will not do. The dung of oxen, buffalo, sheep, goats, horses, and asses, are at the proper time as fit as the dung of camels for this purpose; it is said that even human dung is equal to any other.” In other words, sal ammoniac (ammonium chloride) production from animal dung is influenced by the diet of the animals. Specifically, the quality and quantity of sal ammoniac produced are better when the animals consume fresh, green vegetation compared to dry fodder.”
Through dietary adjustments and concentration methods such as drying and composting, the nitrogen and carbon content of poultry droppings can be significantly enhanced, with nitrogen potentially reaching 3.5-4.2% and carbon content rising to 35-40%. This enhancement transforms poultry droppings into a versatile and efficient resource for ancient metallurgical processes. As a source of carbon and nitrogen, these enriched droppings could play a crucial role in smelting iron ore by contributing to carburization and surface hardening, similar to but more variably than traditional materials. Compared to alternatives, enhanced poultry droppings offer a balanced supply of both nitrogen and carbon: they surpass wood in nitrogen content (wood has negligible nitrogen), are less carbon-rich but more nutrient-diverse than charcoal (which has 85-98% carbon but no nitrogen), and provide a more practical solution than animal bones and hooves, which also contain nitrogen but are less readily available. Consequently, these enriched droppings present a viable, albeit less consistent, alternative to traditional fuels like charcoal and wood, offering unique benefits in ancient iron smelting and metallurgical processes.
It shows the animal droppings were indeed used in iron smelting. You will see that it will keep showing up in a variety of technology sets testifying to the fact that its use in antiquity was pervasive.
Joseph Needham (Mining) on “chi shih” (雞屎白)
A breakthrough came when I looked at the authoritative scholar on Chinese chemistry, Joseph Needham who writes in his work on mining “Thao Hung-ching, the great Taoist physician and alchemist (452 to 536 CE), was even more explicit about this in his Pen Tshao Ching Chi Chu (本草經集註, Collected Commentaries on the Classic of Pharmaceutics of the Heavenly Husbandman), where he denotes the rubbing of iron with a mixture of ‘bird droppings alum’ (雞屎白, chi shihJan), vinegar, and refined copper as ‘plating’ (鍍, thu). Not long after, or perhaps even earlier than Thao’s comment, the San Shih Liu Shui Fa (三十六水法, Thirty-six Methods for Bringing Solids into Aqueous Solution) provides a very detailed description of how to concoct an aqueous solution of jan shih (鹼石) for rubbing on iron to induce this reaction.” (Needham, J., & Tsuen-Hsuin, T. (1985). Science and Civilisation in China: Volume 5, Chemistry and Chemical Technology, Part 1: Paper and Printing. Cambridge University Press.)
Bird droppings alum,” referred to in Chinese alchemy texts as “chi shih” (雞屎白), is a substance that actually refers to bird droppings and was indeed historically used in alchemical and metallurgical practices. This material was believed to have various properties useful in different chemical processes. Specifically, in medieval Chinese alchemy, “chi shih” was employed for its supposed efficacy in purification and transformation processes, often involving metals and other compounds. (Internet Archive) (Oxford Academic)
The use of such organic materials in alchemy aligns with the broader tradition of experimenting with naturally occurring substances to achieve desired chemical reactions, such as creating alloys or purifying metals. This practice reflects the empirical and often experimental nature of early alchemical traditions, which sought to harness the unique properties of various organic and inorganic materials for their transformative potentials (Internet Archive) (Oxford Academic). Again animal droppings feature prominently.
It was as a result of Christa alerting me to the possible link between animal droppings and the development of the smelting process and in particular the hardening of the blades for which you need nitrogen, that the broader realisation emerged of what the level of sophistication in the manipulation of animal dung and urine must have been. By today’s analysis of poultry droppings, it does not work but the folklore is specific! When I started looking at ways that the droppings could be “enhanced” I saw that this “enhancement” was done in Egypt as I just discussed. If I take the enhancement of animal dung in Egypt into account – suddenly it worked. More than worked! Ample carbon to fuel the furnace. Small enough not to clog up the mouth of the furnace after drying and had a concentration of nitrogen that made it perfect for hardening! This made me realise that the manipulation of dung was extremely advanced by the late Bronze Age and early Iron Age!! Which made me reevaluate everything I knew. But it started with emails from a collaborator in Europe insisting that in some way animal droppings had to play a part in early (and later) iron smelting and blade making based on very specific folklore and traditions. I agreed with her that in all my years of looking back into history, such specific data sets from folklore never proved to be completely wrong. The data sets came from a diverse array of sources across a wide geographical area and periods. If not pushed on the point to this extent I would never have seen it!
Animal and Human Urine and Sweat
I first encountered evidence of a link between excrements of animal origin and human culture at the cradle of horse domestication. Horse breeds roamed across the plains and grasslands of Eurasia where major development took place between 2000 BC and 2200 BC. During this narrow window of 200 years a dominant genetic horse population appeared on the Western Eurasian Pontic-Caspian steppe of North Caucasus, east of the Dnieper River within the Don and Volga basins in present-day Russia.
Within a few centuries, the world horse populations of Eurasia disappeared and made way for this dominant horse race. Counting from the present, between 4,600 and 4,200 years ago, it was probably herders living in the Don-Volga region that found a way to increase the local horse reproductive pool which meant that they could reproduce more and more such horses, generation after generation. It would have been understood that one could breed for specific qualities and the increased reproduction resulted in the quick development of the breed.
These horse breeds were famous in the Dan-Volga basin and south past the Caucasus Mountains and around the Black Sea. McCulloch, (1854) wrote that ‘The horses of the Caucasus have been famous from very high antiquity, the Bechtag mountains having been formerly called Hippicon (ἱππικόν) from the number of these animals which were grazed upon its side (Ptolemy, v., 9). They are not less numerous in the present day and are among the very finest varieties of the species.’” (McCulloch, 1854)
The horses were famed throughout the ancient world, and it stands to reason that he is describing none other than the descendants of the earliest domesticated horses, referring to their excellence based on the superior qualities they had for the horseman. In other words, domesticated horses but further refined through selective breeding.
I initially researched this area of the world due to its link with the nitrite-curing community in Turfan. I reasoned that the people who domesticated the horse would have the longest history of “living with horses” and technology sets will still exist that stem from antiquity. Growing up on the farm we called horse sweat salpeter and I was eager to investigate a link between Turfan and horses from a nitrite-producing perspective. I was not disappointed!
Researchers collected evidence from interviews with people involved with horse husbandry in Mongolia and northern Kazakhstan in the recent past. It is these accounts in particular that highlighted the value placed on urine and sweat from these animals. The value of urine is in the fact that it is replete with ammonia, and we know that where we have ammonia, one is likely to find nitrates also which makes it extremely valuable from a meat-curing perspective.
The interviews I referenced give us a glimpse into this ancient past. It was reported that horse fat, excrement, bone, hair, liver, kidney, and stomach are used in the treatment of many ailments. . . Back problems were treated by wrapping the sufferer in a fresh horse skin.” Horse sweat had a very specific medicinal value and is said to cure gastric diseases, ulcers, typhoid fever, plague, fever, and cancer of the gullet.”
The medicinal usage probably followed the discovery of its effect on the meat and the subsequent ingestion of it. Levine, the scholar who did the research said ‘The horse can move rapidly and easily long distances over hard ground, providing its owners with both mobility (riding, packing, traction) and nourishment (milk, meat, fat). Other products, such as bone, hoof, hair, hide, excrement, and even sweat, are also valued, for example, as fuel, raw materials for the fabrication of tools, utensils, musical instruments, and other objects, and for medicinal purposes.’”
The point is that using sweat from horses and their urine and their excrement to cure meat is not farfetched. It dawned upon me that urine, excrement and sweat had all been used in antiquity and probably in meat preservation and curing in particular. From the treatment of our food, it entered medicinal use and gained religious value. When the Dutch arrived in the Cape they documented a ceremony where elders of the Khoe people urinated over the young men. Look at the occurrence to this day of people bathing in cow urine in India, all incidences that give us glimpses of a rich and important place in human culture in the past. All bodily fluids and anything coming out of the body were viewed as having inherent value.
Sweat consists of various salts (mainly sodium chloride), and small amounts of other substances like lactate and urea. From the urea would form nitrates which would be reduced to nitrites and this would cure the meat. Since sweat will only contain small amounts of ammonia, as opposed to urine which will contain large concentrations, the amount of sweat required to cure meat will be substantially more than compared to urine. This would mean that the horse would have to be sweating profusely for curing to take place.
History is replete with examples of ancient horseback riders who cured their meat by hanging strips over the neck of the horse or placing it under the saddle for the sweat of the horse to cure the meat. The fact that meat was placed under the saddles shows the importance of “softening the meat” at a time when people did not have many options for caring for their teeth. The old Boer frontiersmen in South Africa used the same technique to cure meat by hanging it around the necks of their horses when they were out in the bush hunting or tracking.
The ancients had a concept of “living” things containing some “vital” or “vitality” principle. This magical vitality of the living made all fluids and everything from the “living” vitally important, endowed with magical qualities. Urine in the eye of the ancient is not the same as we have today. They would have noticed that the urine from animals (and therefore from humans also) had this magical power to cure meat. Imagine how they would have marvelled that urine could change the colour of meat from dull brown to bright pink and give it longevity! They would have noticed that sweat, if one could get enough of it, had the same effect and that if a horse gallops for even a short time, copious amounts of sweat form. It is therefore easy to see how they would have incorporated older technology sets into their attempts to fully understand all the benefits of the horse.”
The Value Excrement
Related to human faeces, Speth (2017) did such excellent work that I quote him extensively on the subject. “Prehistoric pits filled with human faeces (coprolites) have been found in a number of dry caves in the Great Basin of the western United States. David Thomas (1985: 380–381) discusses these so-called ‘latrines’ at length, noting that in at least some cases such deliberate faecal accumulations occur together with caches of equipment that had clearly been stored in the caves in anticipation of future use. To Thomas, the placement of the latrines side-by-side with other cached items suggests that the faeces had also been stored there, presumably as food reserves for future use. . .” (Speth, J. D.. 2017)
“Arctic groups provide additional insights into forager attitudes toward excrement, and show no evidence, at least in these contexts, that faeces necessarily elicited feelings of disgust, whether through direct contact or by indirect contamination of other items or foods.” (Speth, J. D.. 2017)
“The use of ptarmigan droppings appears to be limited to a few groups of Eskimos. According to Mathiassen…, ‘Ptarmigan excrement is chewed together with walrus meat into a porridgy mass which is stirred up in blubber.’ (Speth, J. D.. 2017)
Similarly, the Netsilik Eskimos are said by Birket-Smith…to have used ‘ptarmigan excrement mixed with blubber and chewed meat’.” (Eidlitz 1969: 88) “Certain remarks and deeds of Pannigabluk’s today prompt Speth to enter certain things about Eskimo cleanliness, etc. Pan. [Pannigabluk] will clean dog excrement off a sole of a pair of boots with her ulu [knife], wipe it casually with a rag that may have had as bad uses a dozen times before, and then proceed to eat with the ulu or cut up with it food for cooking….” (Stefansson 1914: 226)” (Speth, J. D.. 2017)
“The Hadza of Tanzania provides yet another example of humans freely handling faeces with no evidence whatsoever that seeing, smelling, or touching them elicited any sort of disgust response: (Speth, J. D.. 2017)
“Baobab seed is also a good protein source with adequate levels of five out of eight essential amino acids…. The Hadza chew young seeds; but when mature, the seeds are cracked individually with a stone or pounded into a coarse flour…. Baboons, which have teeth well shaped for seed cracking…can not break the mature seeds and pass them unbroken. Hadza women collect baobab seeds from baboon dung piles, wash them, and prepare them in the normal manner….” (Schoeninger et al. 2001: 182)
Throughout much of Southwest and South Asia, manure from cattle, sheep, and other livestock is systematically gathered, kneaded into dung cakes, dried, and stored in and around the house where it serves as an important fuel for cooking and warmth, a component of household architecture, and at times may even be ingested in some form for medicinal purposes.
“Only the dung of the zebu cow was used to plaster the stove and the kitchen area…. For fuel, dung was moulded into relatively flat round cakes which were dried in the sun. Each family had a special place where dung cakes were made and stored…. The women of a family…daily carried dung dropped by the family cattle to this place. Families who owned no cattle collected dung from the village lanes and the grazing area. Traditionally, such dung was available to everyone and it was collected by most families. One important duty of a young daughter was to go early every morning through the village lanes to mark dung that fell from cattle when they were driven to the pond or to the grazing area and later to collect it…One morning we watched a woman from an 11-person family making dung cakes…. She mixed the dung with small pieces of mustard stalks, kneaded it, and formed it into cakes of two sizes which she spread on the ground to dry. In the course of the morning, she made about 24 large cakes and 103 small ones.” (Freed and Freed 1978: 80–81)” (Speth, J. D.. 2017)
““In Iran, manure is an especially valued and carefully treated commodity. Rural and urban communities use it to fertilize the soil, produce energy (burning), eradicate pests and plant diseases, and make bricks and plaster walls. In some cases, it is also used to treat human illness…. For example, the dung of newly born foals mixed with the milk of lactating donkeys is used in some villages to treat whooping cough…. Iranian villagers…utilize animal manure and bird droppings as a source of energy. In some rural areas animal manure is still used to generate heat and women believe that the best fire for baking bread is one made from animal droppings because it produces more uniformly baked and thoroughly toasted bread.” (Ardakani and Emadi 2004: 13)” (Speth, J. D.. 2017)
“As a final example, the Chinese have a long history of using human faeces (‘night soil’) as manure in their agricultural fields. Not surprisingly, there is no hint that either the sight or smell of night soil elicited anything resembling a disgust response in the country’s rural inhabitants: “For crops in a vigorous growing state no kind of manure is so eagerly sought after as night soil; and every traveller in China has remarked the large cisterns or earthen tubs which are placed in the most conspicuous and convenient situation for the reception of this kind of manure. What would be considered an intolerable nuisance in every civilised town in Europe, is here looked upon by all classes, rich and poor, with the utmost complacency; and I am convinced that nothing would astonish a Chinaman more, than hearing anyone complain of the stench which is continually rising from these manure tanks…. In England, it is generally supposed that the Chinese carry the night soil and urine to these tanks, and leave it there to undergo fermentation before they apply it to the land. This, however, is not the case; at least, not generally. In the fertile agricultural districts in the north, I have observed that the greater part of this stimulant is used in a fresh state, being of course sufficiently diluted with water before it is applied to the crops.” (Fortune 1847: 314–315)” (Speth, J. D.. 2017)
“Another favourite in the list of supposed ‘core’ universal disgust elicitors—urine—is also effectively demolished by the cross-cultural ethnographic record and, as in the case of putrid meat, the damning evidence again comes from the Inuit. Urine was their principal ‘soap’! “Urine…is collected from the containers in the men’s house only (since that of women is believed to be unclean), to be stored in tubs for at least two days before using. Women…first bathe in urine, followed by a rinsing in either salt or fresh water. Both sexes frequently wash hands and faces in urine, and rinse with water; for urine, coming into contact with the body oils, acts as soap in removing grease and other impurities. The men, when about to take a sweat-bath…gather in the men’s house. There the floorboards are removed and a roaring fire built in the pit…. The participants, soon drenched with perspiration, bathe themselves with urine from the central pot….” (Curtis 1930: 43)
The Chemical Basis for Using Animal and Human Excrement to Cure Meat
The use of urine in meat curing stems from its high ammonia content. Urine plays a crucial role in the elimination of bodily waste, carrying excess water, salts, and metabolic byproducts filtered by the kidneys. Urea, synthesized in the liver, is a primary component of urine and serves as the body’s method of expelling excess nitrogen. Once excreted, urea transforms, especially under the influence of urease-producing bacteria, which convert urea into ammonia (NH3) and carbon dioxide (CO2).
This conversion, which can occur within the urinary tract or after the urine has been discharged, gives urine its distinctive odour, which becomes more pronounced when concentrated or decomposed. The ammonia concentration in urine is influenced by dietary habits, hydration levels, and overall health, making it a potent curing agent similar to sal ammoniac (ammonium chloride) used in traditional meat preservation.
The conversion of ammonia to nitrite and then to nitrate is facilitated by bacteria through processes called nitration and nitrification. Ammonia-oxidizing bacteria (AOB), if present on the meat or in the environment, can convert ammonia into nitrite (NO2-). These bacteria are commonly found in various environments, including soil and water, and can exist on the surface of the meat or in the storage environment.
Urine contains urea, which bacteria convert to ammonia and carbon dioxide. This ammonia can further undergo nitrification, where bacteria convert it to nitrite and then to nitrate. The presence of ammonia-oxidizing bacteria (AOB) in meat or in the environment helps facilitate this process. Ammonia acts as a curing agent, preserving the meat and inhibiting the growth of spoilage organisms.
The hypothesis I propose about the use of urine in curing meat highlights the ingenuity of ancient practices in food preservation. It was translated into alchemy and traditional medicine where urine was often used for its chemical properties, including its high ammonia content, which was harnessed for various purposes. For example, in Chinese alchemy, urine was viewed as a valuable substance, often used in conjunction with other materials for its transformative properties. Similarly, in European alchemy, human and animal excrement, including urine, were considered potent ingredients for their chemical reactivity and ability to undergo significant transformations.
The study of uric acid, a component found in urine, attracted the attention of many prominent scientists. Friedrich Wöhler’s synthesis of urea in 1828 marked a pivotal moment in chemistry, disproving the theory of vitalism, which held that organic compounds could only be produced by living organisms. This discovery paved the way for further research into organic chemistry and the synthesis of various organic compounds. More about this, later.
The Discovery of Sal Ammoniac and Saltpeter
My thesis is that little mechanisms existed in far antiquity for humans to refine salts, let alone discover their unique properties because they were replete with contaminants and mixed in with various other salts. It is more likely that humans used bodily excrement in domestic settings such as the curing of meat and washing. It makes more sense to me that people came across saltpetre and recognised its properties as similar to what urine provides and thus started to incorporate it into their everyday lives. From urine, they could “calibrate” what to expect saltpetre to accomplish and thus aided in its rudimentary refinement.
Next, I therefore turn my attention to saltpetre and sal ammoniac. Droppings became the primary way of producing sal ammoniac and nitrate salts were produced through mainly urine. Both substances occur naturally and were also made by human ingenuity and I believe, this was motivated by the quest to seek the same effects of ammonia in other substances besides urine. Humans, even in antiquity learned to harness the power of nitrogen. First through the use of urine and excrement and much later through the production of these two salts.
->Sal Ammoniac
The use of ammonia for curing continued in the more recent past, in a time before saltpetre became widely available for medical and military reasons in the form of sal ammoniac. German and Austrian cookbooks pre-1600s reveal that vegetable dyes were used to bolster colour and speak of curing with salt only. It is well known that the Germans and Austrians were familiar with nitrate curing and, I will argue, they would have been acquainted with sal ammoniac as a curing salt also, but no doubt due to the effect of sal ammoniac on taste, it fell out of common use.
Both sal ammoniac and saltpeter were well known in Mesopotamia and references to them appear alongside references to salt curing of fish and both salts were used in meat curing. The ancients developed basic techniques for separating the different salts. In particular, sal ammoniac was by far the most important salt of the bronze age (2000 BCE). It was produced in Egypt where it appeared around the kilns where camel dung was used as fuel for the fire and mined in Asia. When the horse was domesticated around 5000 BCE, a food source was needed to sustain humans on long expeditions and I believe sal ammoniac fits the requirement perfectly.
Both salts cure the meat in a week which has huge advantages compared to salting the meat with normal table salt. In my experience, salt ammoniac is, however, a far better preservative than saltpetre. Sal ammoniac, as far as I can find, was globally traded much earlier than saltpetre. Ancient Macedonian records indicate that even in 2000 BCE saltpetre was preferred in food over sal ammoniac on account of the better taste of saltpetre. Still, sal ammoniac was far more vigorously traded than saltpetre in the early Christian era and possibly for thousands of years before that.
-> Natural Sal Ammoniac
Sal ammoniac is a salt that occurs naturally and is made by human endeavour. Turpan is the name of an oasis in the far western regions of China. It is an extremely dry area. Turpan is also probably the only place on earth where sal ammoniac and nitrate salts in the form of sodium nitrate occur in massive quantities side by side. Sal ammoniac, in the surrounding mountains and nitrate salts on the basin floor.
Chinese authors of antiquity are unanimous that sal ammoniac came into China from Turpan, Tibet, and Samarkand and through Samarkand, it was traded into the Mediterranian along the Silk Road. It all makes for an appealing case for sal ammoniac as the actual curing salt from antiquity that was used in meat curing when the practice spread around the world. There is even a tantalizing link between Turfpan and the ancient city of Salzburg and the salt mines which leads me to speculate that the trade of sal ammoniac was done into the heart of Western Europe, into what became known as Austria. This leads me to believe that the actual technological progressions related to meat curing may have come from Austria. Whether it was through Salzburg and initially from Turfan is not clear.
It was exploring this link that introduced me to Christa Berger who collaborate so widely with me now in Earthworm Express. It stems from the wide subject range we discuss related to antiquity and human culture and from her practical 1st hand knowledge of the meat industry from their own farm and not from a university setting. She explored the link between Turpan and Austria in great detail and elucidated this link tremendously. More on that in a separate article which I must still write.
Around Turpan (also called Turfan), sal ammoniac forms in volcanic vents and after volcanic eruptions before it rains which dissolves the crystals. It is highly soluble. It is unique in that the crystals are formed directly from the gas fumes and bypass the liquid phase, a process known as sublimation. The Turfan area, both the basin and the mountains are replete with different salts containing nitrogen (nitrate salts and ammonium) any one of which could be used effectively in meat curing.”
The sal ammonia was mined from openings in the sides of volcanic mountains where steam from underground lava flows created ammonium chloride crystals. These were traded across Asia, Europe and into India. Massive sodium nitrate deposits occur in the Tarim Basin, the second-lowest point on earth. I then speculate that traders used some of these deposits to forge ammonium chloride since the ammonium chloride crystals did not survive in crystal form on long voyages due to their affinity for water which breaks the crystal structure down. Once this happened, the sodium nitrate and the ammonium chloride look similar. Because it is known that almost all the sal ammonia produced in Samarkand was exported, I deduce that demand outstripped supply and this provided the incentive for such forgery. I find support for the likelihood of such a forgery, not just in the limited supply of sal ammoniac compared to nitrate salts, but also in the fact that mining sal ammoniac was a seasonal affair and an extremely dangerous and difficult undertaking.
I suspect it was the observation of these natural events that produced sal ammoniac and tentative observations of ancient humans who burned excrement of fuel for their fires who recognised a similar basic principle at work and from there they worked out how to create sal ammoniac from dung.
It seems likely that sal ammonia was the forerunner of saltpetre as the curing agent of choice. It is composed of two ions, ammonium, and chloride. The ammonium would be oxidized by ammonia-oxidizing bacteria (AOB) into nitrites and the well-known reaction sequence would follow.
Sal ammoniac was also mined from the earth. In China, ancient names given for Sal Ammoniac are “red gravel” and “essence of the white sea.” There were sal ammoniac mines in Soghd. Mohammadan traders passed it at Khorasan travelling towards China. Kuča still yielded sal ammoniac at the beginning of the 1900s. There are ancient references to white and red varieties of sal ammoniac. The mines in Setrušteh or سمرقند (Samarkand in the Persian language) are described in classic literature as follows. “The mines of sal ammoniac are in the mountains, where there is a certain cavern, from which a vapour issues, appearing by day like smoke, and by night like fire. Over the spot whence the vapour issues, they have erected a house the doors and windows of which are plastered over by clay that none of the vapour can escape. On the upper part of this house the copperas rest. When the doors are to be opened, a swiftly-running man is chosen, who, having his body covered over with clay, opens the door; takes as much as he can from the copperas, and runs off; if he should delay he should be burnt. This vapour comes forth in different places, from time to time; when it ceases to issue from one place, they dig in another until it appears, and then they erect that kind of house over it; if they did not erect this house, the vapour would burn, or evaporate away.” (Laufer,1919) “Tibetans received this salt from India as can be seen from an ancient name they gave to it namely “Indian salt.” There are records that it was harvested from certain volcanic springs from Tibet and Se-č’wan. (Laufer,1919) The same vapours are seen in the smokey mountains of Turfan.”
-> Human-Made Ammonium Chloride
Just like saltpetre, sal ammoniac occurs naturally and is also generated by human ingenuity. Armed with what they saw in nature and what they undoubtedly observed in confined spaces and around kilns, where dung was used as fuel, the worked out how to make it themselves. The name, ammonia, came from the ancient Egyptian god, Amun. The Greek form of Amun is Ammon. At the temple dedicated to Ammon and Zeus near the Siva Oasis in Lybia, priests and travellers would burn soil rich in ammonium chloride. The ammonium chloride is formed from the soil, being drenched with nitrogen waste from animal dung and urine. The ammonia salts were called sal ammoniac or “salt of ammonia” by the Romans because the salt deposits were found in the area. During the Middle Ages, ammonia was made through human endeavour through the distilling of animal dung, hooves, and horns. (Myers, RL. 2007: 27)
The New York Tribune of 31 January 1874 wrote the following. ‘For centuries sal ammoniac was imported from Egypt where it is sublimed from camels’ dung.’ An article, published in 1786 on Friday, 18 August in the Pennsylvania Packet, described the process of making sal ammoniac in Egypt as follows.’ Sal Ammoniac is made from soot arising from the burnet dung of four-footed animals that feed only on vegetables. But the dung of these animals is fit to burn for sal ammoniac only during the four first months of the year when they feed on fresh spring grass, which, in Egypt is a kind of trefoil or clover; for when they feed only on dry meat, it will not do. The dung of oxen, buffalo, sheep, goats, horses, and asses, are at the proper time as fit as the dung of camels for this purpose; it is said that even human dung is equal to any other.’
The soot arising from the burnt dung is put into glass vessels, and these vessels into an oven or kiln which is heated by degrees and at last urged with a very strong fire for three successive nights and days, the smoke first shows itself, and, in a short time after, the salt appears sticking to the glasses, and, by degrees, covers the whole opening. The glasses are then broken, and the salt is taken out in the same state and form in which it is sent to Europe. At this time, Egypt was one of the major suppliers of sal ammoniac to the European continent.
-> Saltpetre
Progressing from urine and dung, humans accessed the power of nitrogen to cure meat through saltpetre. In the following section, I want to show the level of mysticism surrounding saltpetre. A second point I want you to notice is how “recent” the discoveries surrounding saltpetre and sal ammoniac is.
Since recent antiquity, all over the world, from Mesopotamia to China, they knew about certain potent salts that changed the colour of the meat to reddish/ pinkish and gave it longevity! The reddening effect of saltpetre in meat curing was well-known in late Roman times.
These ancients could not tell if saltpetre occurred naturally or if was it something that had to be nourished or cultivated by humans. They wondered how to take the impurities out of the salt. Nobody could explain its energy. Saltpetre had many ancient uses. To cure meat, and as an essential ingredient in gunpowder, as fertilizer, medicine, for cooling beverages and in glass-making.
Almost every great civilization used it to cure meat. The Chinese and Italians used it to make gunpowder. There is a record of gunpowder being used in India as early as 1300 BCE, probably introduced by the Mongols.
Saltpetre was used in ancient Asia and Europe from the 1500s to cool beverages and to ice foods. “Essentially, during the process of the saltpetre dissolving in the water, the energy needed to break the bonds of the salt pulls heat from the surrounding water, thus decreasing the overall temperature in the basin”.
The first reported references to the characteristic flavour of cured meat produced by the addition of saltpetre during meat preservation and curing were made as early as 1835. Some speculated, that it contained the “Spiritus Mundi”, the ‘nitrous universal spirit’ that could unlock the nature of the universe!
These elevated views of saltpetre and how it was celebrated and romanced in the Middle Ages indicate the place of reverence, in my mind, not necessarily to saltpetre itself, but the outcomes it brought! I am listing more of these statements about saltpeter from our recent past where its nature is celebrated. The same nature that is found in urine.
Peter Whitehorney, the Elizabethan theorist wrote in the 1500s about saltpetre, “I cannot tell how to be resolved, to say what thing properly it is except it seemeth it hath the sovereignty and quality of every element”. Paracelsus, the founder of toxicology who lived in the late 1400s and early 1500 said that “saltpetre is a mythical as well as chemical substance with occult as well as material connections.” The people of his day saw “a vital generative principle in saltpetre, ‘a notable mystery the which, albeit it be taken from the earth, yet it may lift up our eyes to heaven”
From the 1400s to the late 1800 scientific writers probed the properties of this magical compound. People said that “Saltpeter encompassed the “miraculum mundi”, the “material universalis” through which ‘our very lives and spirits were preserved. Its threefold nature evoked ‘that incomprehensible mystery of … the divine trinity,’ quoting Thomas Timme who wrote in 1605, in his translation of the Paracelsian Joseph Duchesne.
“Francis Bacon, Lord Chancellor and Privy Councillor under James I, described saltpetre as the energizing “spirit of the earth.” “Robert Boyle who did experiments trying to understand saltpetre found it, ‘the most catholic of salts, a most puzzling concrete, vegetable, animal, and even mineral, both acid and alkaline, and partly fixed and partly volatile. The knowledge of it may be very conducive to the discovery of several other bodies and to the improvement of diverse parts of natural philosophy.”
In India, they mined saltpeter from the earth and thousands of small villages were engaged in its production. It grew like fungus on the walls of cellars and around toilets. It seemed as if it occurs wherever urine and dung occur such as in bat caves.
In Germany, they developed technology whereby they created their own saltpetre. So versed in its production was the average person in Germany that authors at this time did not even bother to detail the processes.
Lazarus Ercker (1530-1594), chief master of the mines of Emperor Rudolph II in Bohemia, wrote arguably the most detailed account of the production of saltpetre in ‘The right and most perfect way of the whole work of saltpetre’. A German translation appeared in Prague in 1574 and in Frankfurt in 1580.
Still, despite the impact of the Renaissance and tremendous advances in the fields of biology and the natural sciences, people could only appreciate saltpetre by what it did without any understanding of how it worked.
In the late 1770’s a chemical instructor said about saltpetre: “‘We are much in the dark as to the origin and generation’ of saltpetre, though he knew it to be ‘found among earth and stone that have been impregnated by animal and vegetable juices susceptible of purification and have long been exposed to air. . . . It is the product of the elements deposited in the bosom of the earth, and may not be improperly called the universal and unspecific mercury”.
“Written knowledge of saltpeter filtered into England in 1540 with Vannoccio Biringuccio’s De la pirotechnia. This work was eventually translated into English and included accounts of the making of explosives.
Naturally, it is found in countries with a warm climate and high rainfall, “ammonia resulting from the putrefaction and decay of nitrogenous materials is washed into the soil by rainfall, to be oxidized by bacteria, yielding nitrate. . . In countries like India, saltpetre is leached from the ground as sheets of water left by monsoon flooding evaporate. A crust of saltpetre, including mineral salts, spreads across the ground, and can be dug up and refined into pure potassium nitrate.”
It is also made by human endeavour. Where the people of Germany chose to make their own saltpetre, in England they harvested saltpetre earth and extracted it from the nitre-enriched soil. Saltpetermen scoured the English countryside and dug up any place where the ground could have been impregnated with animal and human urine and dung.
Peter Whitehorn, the Elizabethan theorist said that saltpetre ‘is a mixture of many substances, gotten out of fire and water of dry and dirty ground.’ It could sometimes be found as an efflorescent or ‘flower that grows out of new walls, in cellars, or of that ground that is found loose within tombs or desolate caves where rain can not come in.’ But saltpetre could also be nourished or encouraged to grow by adding ‘the dung of beasts’ to the earth. A distinction was made between ‘natural saltpetre’ which only needed to be scraped from walls, and ‘artificial saltpetre’, which required digging and refinement. The two kinds ‘partook of the very same virtue’ (according to Whitehorn, relaying Biringuccio) except that some /beasts, converted into the earth, in stables or in dunghills of a long time not used”.
After the 1850’s the East Indian Company solved the supply problem of Saltpeter by importing it from India where it occurred naturally and was also efficiently produced. It was the largest traded commodity by weight of the Dutch East Indian Company which established the trading post at the Southern tip of Africa that later became Cape Town.
The breakthrough as to its chemical composition came from the work of Antoine Lavoisier in 1777 when he analysed nitric acid. Saltpetre followed in the footsteps of how urine and excrement were viewed for probably many thousands of years.
The Priority of Uric Acid
The synthesis of uric acid was a monumental achievement in the field of organic chemistry, marking one of the first instances of a complex biological compound being artificially replicated in the laboratory. In light of our present discussion, we have to ask the question of why was urine of such fundamental interest and priority. The fact that it was the first organic compound to be synthesized shows the intensity with which it was studied with. It is fair to say, “like no other substance at that time!” It supports my main thesis.
The breakthrough in understanding urine came through the German chemist Hermann Kolbe in 1860. His remarkable feat that built upon the foundational work of earlier scientists who had identified uric acid in urine. Uric acid was initially discovered in human urine in the early 18th century by Carl Wilhelm Scheele, a Swedish chemist renowned for his work in identifying new chemical substances. The interest in uric acid stemmed from its presence in urine, a substance that held considerable significance in both ancient and early modern science due to its perceived medicinal properties and its role in the body’s excretory system.
Kolbe’s synthesis of uric acid was not an isolated event but rather the culmination of extensive research efforts by numerous chemists who recognized the importance of understanding the biochemical processes underlying life. Before Kolbe, Friedrich Wöhler had already demonstrated the synthesis of urea from ammonium cyanate in 1828, challenging the prevailing belief that organic compounds could only be produced by living organisms. This breakthrough paved the way for further exploration into synthesizing other organic molecules, including uric acid. The successful synthesis of uric acid by Kolbe involved the oxidation of uric acid derivatives and further cemented the notion that complex organic molecules could be produced from simpler chemical precursors.
The synthesis of uric acid and its earlier identification in urine showed how important the role was that urine and its components played in the evolution of chemical and medical sciences. Throughout antiquity and into the early 19th century, urine was regarded as a valuable diagnostic and therapeutic substance, with its analysis providing insights into the body’s health and functioning. The ability to synthesize uric acid not only advanced the understanding of organic chemistry but also highlighted the potential for chemical synthesis to replicate and study the components of living organisms. This breakthrough laid the groundwork for modern biochemistry and pharmacology, demonstrating the critical intersection between chemistry and biology.
The successful synthesis of uric acid by Kolbe was part of a broader scientific revolution that fundamentally altered the understanding of life itself. This period saw the discrediting of the vital force theory, or vitalism, which posited that living organisms were fundamentally different from non-living entities due to a “vital force” unique to biological processes. The vital force theory held sway over scientific thought for centuries, suggesting that organic compounds could only be synthesized within living organisms through processes imbued with this mysterious force.
Friedrich Wöhler’s synthesis of urea in 1828 is often cited as the watershed moment in the overthrow of vitalism. By converting ammonium cyanate, an inorganic compound, into urea, an organic compound found in urine, Wöhler demonstrated that organic molecules could be synthesized from inorganic precursors without the need for a vital force. This experiment undermined the core premise of vitalism and paved the way for the development of organic chemistry as a field capable of exploring and replicating the substances and processes of life through purely chemical means.
Kolbe’s subsequent work, including his synthesis of uric acid, further solidified the demise of vitalism by showing that even more complex organic compounds could be synthesized in the laboratory. This transition marked a significant paradigm shift, leading scientists to view biological processes as a series of chemical reactions governed by the same principles that apply to non-living matter. The rejection of vitalism was a crucial step in the evolution of modern biochemistry, opening new avenues for research and leading to a deeper understanding of the molecular underpinnings of life.
The priority of uric acid shows the role and place urine had till the very present and the story about the vital force sheds light on why it had the prominent position it held.
Exploration of Nitrite and Nitrate Salts From Mesopotamian Meat Preservation
The document “A Study of Diet in Mesopotamia (c. 3000 – 600 BC) and Associated Agricultural Techniques and Methods of Food Preparation” by Elizabeth Rosemary Ellison, submitted to the University of London in May 1978, provides insights into the biochemical processes involved in nitrogen metabolism, highlighting the formation and role of nitrogenous compounds such as urea and ammonium carbonate. These compounds are present in urine its preservative properties would have aided meat preservation by urine in ancient meat preservation practices.
Urea is a significant nitrogenous waste product excreted by mammals, formed primarily through the breakdown of proteins and amino acids. The document discusses the biochemical pathways leading to the formation of urea, highlighting the role of cyanic acid and the intermediate formation of ammonium carbonate. It states, “The chemical relations between urea and ammonium carbonate, as well as ammonium carbamate, suggested themselves as simple and obvious. Ammonium carbonate, a well-known compound, when heated is decomposed into water, carbon dioxide, and ammonia” (Ellison, 1987).
Ammonia and ammonium carbonate are key nitrogenous compounds present in urine. The document explores the stability and hydrolysis of calcium carbamate and calcium cyanate in urine, pointing to the presence of these compounds in biological systems. She writes, “When ammonium carbamate is formed, a spontaneous decomposition sets in, resulting in the production of water and gaseous ammonia, indicating the presence of such compounds in urine” (Ellison, 1987).
Various biochemical reactions involving urea, ammonia, and cyanic acid are detailed, emphasizing their role in nitrogen metabolism. The breakdown of amino acids and the formation of urea through dehydration and hydrolysis are explained, providing a foundation for understanding the chemical properties of urine. “The decomposition of ammonium cyanate into urea is one of the simplest transformations. This reaction is pivotal in the metabolism of nitrogen and indicates the biological importance of urea in both plants and animals” (Ellison, 1987).
While the document does not directly discuss the use of urine for meat preservation, the biochemical principles outlined suggest its potential effectiveness. Urine contains ammonia, which by itself is a preservative which creates an alkaline environment that inhibits bacterial growth. In my own studies where I used ammonium chloride and compared it as a preservative against sodium nitrite, ammonium chloride far outperformed nitrite salt.
Additionally, the conversion of ammonia to nitrites and nitrates by bacteria will facilitate meat curing. The document supports this by stating, “Ammonia, due to its basic properties, is capable of inhibiting microbial growth, making it a potential preservative” and “The transformation of ammonia into nitrites and nitrates through bacterial action is a well-documented process, crucial in the natural nitrogen cycle” (Ellison, 1987).
The biochemical processes described in the document validate the hypothesis that urine, with its nitrogenous compounds, could have been an effective and consistent preservative in ancient meat preservation practices. The consistent ammonia content in urine would likely provide more reliable results compared to variable plant-based methods or naturally occurring nitrate salts, which were often contaminated and less predictable.
Although Ellison (1987) does not explicitly mention the use of urine for meat preservation, the underlying biochemical principles support the feasibility of this practice. The stable presence of ammonia and the potential for bacterial conversion to nitrites and nitrates suggest that urine would have been a viable option, effectively used in ancient times to preserve meat. This hypothesis aligns with the known properties of ammonia and its role in inhibiting bacterial growth, providing a plausible explanation for urine’s use in historical preservation methods.
Conclusion
My research into the origins of meat curing has shown that ancient peoples were highly adept at utilizing human and animal excrement, including urine and manure, in a wide array of applications, ranging from meat preservation to medicinal practices. Over tens of thousands of years, and possibly longer, they understood the properties of these substances and integrated them into their cultural, religious, and practical daily lives.
Through meticulous observation and experimentation, ancient humans identified the relationship between urine and saltpetre (a nitrate salt) and between droppings and sal ammoniac (ammonium chloride). Although they did not grasp the underlying chemistry, their focus on practical application led to the development of methods for creating nitrate salts and sal ammoniac from excrement. These methods became foundational elements in the emerging systems of alchemy, where the use of dung and urine was so entrenched that even the advent of more refined salts could not diminish their importance.
This brings me back to the ancient curing vats at Hallstatt dating back to 1200 BCE. Christa Berger alerted me to it and so began one of the most productive scientific collaborations of my life! The existence of the Hallstatt curing vats supports the hypothesis that these practices were widespread. These vats provide a glimpse into the industrial-scale applications of what likely began as small-scale, private endeavours. The tradition of using urine and dung in meat curing, informed by empirical knowledge and evolving over millennia, underscores the ingenuity and resourcefulness of our ancestors. As I continue to piece together the historical and scientific evidence, I am more convinced than ever of the central role that these ancient practices played in the development of meat-curing techniques.
Supporting Evidence and Further Work
A Newspapers Record of the Use of Urine and Dung
The Role of Animal Droppings and Pattern Welding in Ancient Sword Making: A Blend of Art and Science
The Role of Urine as a Filtration System for Amanita Muscaria and Other Uses Across Eurasia
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