Chapter 12.06: From Sea to Deserts – Sal Ammoniac, Urine and Horse Sweat

Introduction to Bacon & the Art of Living

The story of bacon is set in the late 1800s and early 1900s when most of the important developments in bacon took place. The plotline takes place in the 2000s with each character referring to a real person and actual events. The theme is a kind of “steampunk” where modern mannerisms, speech, clothes and practices are superimposed on a historical setting. Modern people interact with old historical figures with all the historical and cultural bias that goes with this.

narrative – the history of bacon

From the Sea to Turpan

University Geology Museum (1), Copenhagen, June 1891

Dear Children,

The day has finally arrived, our much-anticipated visit to the University of Copenhagen’s Geology Museum. It is located in Nørregade. The museum is part of the Natural History Museum of Denmark. It was exceptional. The exhibition of minerals is, from what I am told, one of the finest in Europe! There are exhibitions on meteorites, volcanoes, continental drift, the geology of Denmark, the geology of Greenland, fossils (including the largest bivalves such as clams, mussels, oysters, and scallops), and an exhibition on the origin of humans. The fact that we had to postpone the trip for a week worked out well. Despite Uncle Jeppe being unable to join us, the Curator of the Museum was there and what happened was beyond our expectations! He proved to be just the man to be bombarded with my many questions!


Bezeklik caves on mountain slopes near Turfan

The Curator and My Research Partner

It was just a stroke of luck that the curator of the museum was on duty himself. Dr Hans Thirsten is a scientist with a single-minded dedication to the earth we live on. (2) His area of speciality is focused on solving many of societies pressing challenges. He agreed to have coffee with us and answer our questions. This is the thing about the Danish that I notice wherever I go – they don’t have inflated egos and it is true of Dr Hans. If this was in Cape Town, I cannot imagine that someone with his position would have taken the time to have coffee with us and answer a novice in the area of minerals, chemistry and geology so many many questions. Minette is the right research partner! She asks simple but powerful questions. She is never afraid to ask for clarification on points of seeming contradiction.

From Sea to Dry Deserts

Dr Hans patiently listened to my questions before he started speaking. He was very polite in letting me finish my questions and then he was also polite enough to completely disregard them and started at a place where I lacked general understanding before he returned to the specifics of my questions that were not addressed by his general introduction. Not one of us minded his approach. It was all fascinating and he had Minette, Andreas, his dad, his mom, and me hanging on to his every word.

First, the professor had to set me right in a wrong perception I had about how salts naturally occur on earth. I did not understand that today our salts are very refined. Impurities are removed before it is sold. Different salts are neatly separated but in nature that is not how they occur. In nature, salt exists as a mixture of various minerals. When the ancients talked about saltpetre, for example, there were many different grades of purity. The nitrate salts may be mixed with what we refer to as table salt or sodium chloride along with many other chemical compounds. The opposite also occurs. If salt is mined from a salt pan, for example, there may be nitrate salts mixed in.

The other matter that he cleared up is that of terminology. Different civilisations referred to the same salt by different names and sometimes used the same name to refer to different salts. This means that the historical consideration of minerals and salts must be done carefully and one must always look at the characteristic of the salts described and not make an assumption about the nature of the salt based on what it is called.

With these sobering thoughts, Dr Hans continues. “The real question relates to sources of nitrogen that could potentially end up as nitric oxide in meat which you know is the actual curing molecule and not nitrate or nitrite.” His knowledge of meat curing was based on his general knowledge of the subject matter which was vast!

“In this regard, everywhere and anywhere we have to do with any of the various forms of nitrogen in nature, we have a possible source for meat curing. Since nitrate is far more stable than nitrite which acts only as an intermediate species of nitrogen and since nitric oxide is a gas, the most stable source of nitrate will be in a form of a salt such as potassium nitrate or sodium nitrate. All salts eventually end up in the sea and one would expect the sea to be a large source of nitrate. It is therefore not surprising that while people living in desert areas would have noticed certain salts to have the ability to change the colour of meat from brown, back to pinkish/ reddish, along with increased preservation power and a slightly distinct taste, it is certainly true that coastal dwellers would have observed it first.”

“The reason for this is that the earliest human communities settled near the coast and migrated to other regions following the coastline, it is reasonable to assume that the reddening effect of certain salts was observed by these communities first. They would have seen that sea salt or bay salt has this ability despite nitrite and nitrite occurring in very small quantities in sea salt (less than 2ppm). One of the earliest ways of preserving meat was to store it in water. So, on sea journeys, the earliest people probably had some meat stored in some sort of vessel filled with water.”

“They would have noticed the following, even if there were no nitrate in the water: since proteins contain nitrogen when the meat is placed in seawater, the surface proteins are proteolised and deaminated to ammonia. The process is called ammonification and happens quickly in water. Ammonia or ammonium is oxidised to nitrite in a process that is referred to as nitration by ammonia oxidising bacteria (AOB). Nitrite is oxidised by nitrite oxidising bacteria (NOB) in the second step of nitrification. (Domingos, 2011)” In this way, simply storing the meat in water would have generated many of the nitrogen species and for our purposes, these include nitrate and nitrite.

Dr Hans ordered a second cup of strong coffee! His mannerism is controlled and he speaks in an almost monotone voice. We all remained spellbound. I could not even look up as I was furiously trying to keep up taking notes and I was thankful every time he paused to take a sip of his coffee. “I suspect that people discovered this even long before barrels were invented. In general, coastal communities used seawater for meat storage and the practice was so widespread that it would have been impossible not to have noticed meat curing taking place. If it is generally true that the earliest humans first settled around coastal locations before migrating inland, it could push the discovery of curing many thousands of years earlier than we ever imagined, to a time when modern humans started spreading around the globe. The process I described of forming ammonium and bacteria converting the ammonia into nitrite and nitrate is also true for fresh water. The fact that the seawater contains some salt had nothing to do with it. More important, is the type of bacteria found in the seawater but the same bacteria would also be present in freshwater. The fact is still that nitrate and nitrite would be generally “closer” to the communities living by the sea in sea salt whether it was collected from the bay or through solar evaporation, from regular seawater as nitrogen is an important nutrient in the water for microorganisms and plants in the water, alike.”

“When did it develop into an art or a trade is another question altogether, but, speculating about this, I think we can safely push the time when it was noticed back to the earliest cognitive and cultured humans whom we would have recognized as thinking “like us” if we could travel back in time and meet them. I think the question of when they recognised this in various regions to the time when these areas were populated.”

“Even though I now suspect that curing was first noticed by communities living by the sea as I just explained, I suspect inland dwellers discovered salt that cures meat in deserts also. As I already said, salt in nature almost always appears as a mix of various salts and under certain conditions, these salt deposits contain small amounts of nitrate salts, ammonium chloride and sometimes even nitrite. The ancients would have noticed that these salts cure meat. We mostly think of saltpetre as the earliest curing salt from the desert, but I think there is another salt that possibly pre-dates the widespread use of saltpetre as curing agent and that is sal ammoniac.”

Sal Ammoniac

“The most important two curing salts that appear to us from antiquity are saltpetre (sodium or potassium nitrate) and sal ammoniac (ammonium chloride). Both salts were well known in Mesopotamia and references to them appear alongside references to salt curing of fish mentioned earlier and both salts were used in meat curing.”

I was riveted! “The ancients developed basic techniques of separating out the different salts. In particular, sal ammoniac was by far the more 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 it was 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 obviously had 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. As is the case we discussed in seawater, ammonium chloride undergoes a bacterial transformation into nitrites which will then in the meat matrix yield nitric oxide which will cure the meat. Using sal ammoniac directly would result in quicker curing of the meat than leaving the meat in water, sea water or fresh.

Natural Sal Ammoniac

Sal ammoniac is a salt that occurs naturally and is made by human endeavour. He introduced us to a region of the word that I did not even know existed. “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.”

“Around Turpan (also called Turfan), sal ammoniac forms in volcanic vents and after volcanic eruptions before it has rained 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 the 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. Due to the fact that 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 extremely dangerous and a difficult undertaking.”

Natural Sal Ammoniac occurs in places like the Turpan and Samarkand. An important branch of the silk road runs from Turfan through Samarkand and into Europe. Samarkand is a city in south-eastern Uzbekistan. It is one of the oldest continuously inhabited cities in Central Asia.

“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 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. 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 firsts 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.”

Flaming Mountains.jpg
Flaming Mountains of Turfan

Ammonium Chloride (Sal Ammoniac) Chemistry

“We have seen that nitrite is formed by removing an oxygen atom from nitrogen. It was the Russian microbiologist Sergei Winogradsky who discovered that certain microorganisms create nitrite and nitrate from ammonia through a process called biological oxidation. Have a look at how oxygen is added at every step. Ammonia is NH3 and there is no oxygen. Nitrite is formed (NO) which is the nitrogen and two oxygen atoms. From nitrite, through bacterial action, nitrate is formed (NO3). We have to understand a bit more about ammonia to see how this works. This will be very important when we look at the decomposition of animal tissue and in animal urine and excrement since it contains copious amounts of ammonia. The building blocks of ammonia are seen in its chemical formulation. Ammonia is a compound of nitrogen and hydrogen with the formula NH3. In nature, ammonia exists as NH3 or its ammonium ion (NH4+). The ammonium ion, in nature, also combines with a metal such as chlorine to form a salt of ammonium. Ammonium is therefore not only important in the nitrogen cycle, but also in meat curing in the form of a salt where a metal such as chloride combines with the ammonium ion to form ammonium chloride (NH4Cl). It is the NH4 that makes it mildly acidic and the new molecule of sal ammoniac or ammonium chloride is highly reactive with water. Ammonium chloride occurs naturally as a crystal and is formed through the action of bacteria on decomposing organic material. As a salt, it is one of the iconic salts of antiquity.

“Not only would it result in the reddish-pinkish cured colour, but it was an excellent preservative. An 1833 book on French cooking, The Cook and Housewife’s Manual by Christian Isobel Johnstone states that “crude sal ammonia is an article of which a little goes far in preserving meat, without making it salt.” (Johnstone, C. I.; 1833: 412) It is, of course, the sodium which tastes salty in sodium chloride and ammonium chloride will have an astringent, salty taste. I know exactly what ammonium chloride tastes like since it was added to my favourite Dutch candy “Zoute Drop” with liquorice.”

The Turfan Priority

“The reason for the interest in the Turfan region, as with the Atacama region in Chili and Peru where massive nitrate deposits exist was in the first place the existence of the oldest naturally mummified human bodies. In both the Atacama region and the Turfan depression, natural mummification occurred as a result of the driest climate on earth and the very cold nighttime temperatures, but also due to the natural presence of nitrate in the soil. The link between what the people observed in their relatives not decaying and the salts that contributed to this was obvious to the inhabitants of these regions. Besides this, Turfan was a major trading location with ample contact with the rest of the world for them to know how unusual this is.”

The professor from the geology museum pulled the curtains of his thoughts back as he sat, relaxed in a comfortable chair and looked at all the evidence he considered over the years. He thinks that Turfan plaid a role in changing nitrite curing into an art. The first and obvious reason is the fact that such large deposits of nitrate exist in the depression and in contrast to the huge quantities that exist in the Atacama Desert, these deposits occur on the top layer of the soil making it much more accessible. His second reason is the occurrence of sal ammoniac in close proximity to nitrate. The fact is that these are two completely different salts and despite the tantalising possibility of the one being traded for the other, people in the region must have developed the skill from early on to distinguish between the two. There is evidence that the different salts were often confused, but a basic understanding of the distinct properties of each salt would have developed among the population. Evidence from Turfan shows that sal ammoniac was one of the most traded commodities.

A third clue comes to us in the form of evidence of a sophisticated understanding of nitrate salt as medicine in the general proximity of Turfan. This comes to us from a city about 800kg to the east, Dunhuang.

On 25 June 1900, a Daoist monk, Wang Yuanlu, discovered a manuscript in the Mogao caves close to Dunhuang. It is a mix of religious and secular documents dating from the 5th to the early 11th centuries. One text is of particular interest to us, referred to as the Dunhuang Medical Text. The text is attributed to the famous Daoist alchemist and physician Toa Hongjing (CE 456 – 536).  (Cullen, C, Lo, V.;  2005) There is evidence that it relies on earlier traditions from the Han and Sui Dynasties. “The original was decorated with images of the Three Daoist Lords and the Twelve Constellations, indicating links with Doist traditions.” In translation, it reads as follows:

From Cullen, C, Lo, V.;  2005

“The symptoms presented by the patient point to some sort of cardiovascular distress. The colour of the fingernails (cyanosis) indicates a lack of oxygen in the tissue caused by restricted blood flow. Cold hands and feet point to the same. The pain suffered by the patient may indicate severe angina, i.e. restricted blood flow due to the narrowing of the cardiac arteries.”

“Modern treatment for angina is glyceryl trinitrate or isosorbide dinitrate. So, at first glance, there seems to be a similarity in treatment, but these are organic nitrates which can be used by the body to resolve the restricted blood flow. It does this by converting it through enzymes into nitric oxide. Saltpetre is inorganic and by itself will not have any effect to relieve the symptoms. The body does not have enzymes that will convert nitrate to nitric oxide which is the agent responsible for initiating the sequence that leads to a resolution of the restricted blood flow.”

“This is, however, not the full story. The remarkable feature of the Dunhuang text is that the combination of the use of saltpetre (which is nitrate), not on its own, but when applied according to the dictates of the text, becomes a remedy for exactly the condition described. Under very special circumstances, exactly as detailed in the Dunhuang text, beginning with the microbial conversion of nitrate to nitrite by bacteria in the tongue, the nitrate ion from saltpetre converts into a species which is able to be changed in the body to nitric oxide which resolves the symptoms. This substance is nitric oxide. An interesting side note is that the tongue, in traditional Chinese medical theory, is linked to the function of the heart.”

Horse Sweat and Urine

The development of dry curing, as well as nitrate curing into a well-structured and regulated process, was driven by the need to feed armies and navies. The one event that rivalled long sea journeys in contributing to the emergence of these disciplines was the domestication of the horse.

Various horse breeds roamed across the plains and grasslands of Eurasia. A 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 4,600-4,200 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 all the way past the Caucasus Mountains and around the black seas. “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)

“These horses were indeed 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.”

“Researchers collected evidence from interviews with people involved with horse husbandry in Mongolia and northern Kazakhstan in the recent past or present. It is clear that the urine from horses was prized as all urine was prized by the ancients. Urine is of course replete with nitrates and ammonia and would have been an ideal candidate for meat preservation. The interviews I referenced above 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 usages probably followed the discovery of its effect on the meat and the subsequent ingestion of it. Levine, the scholar who did the research said that “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 to cure meat is not farfetched. I had a suspicion for a long time that urine and sweat had both been used in antiquity in meat preservation and from food, it entered medicinal use and gained religious value. When the Dutch arrived in the Cape they documented a ceremony where elders 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.”

“The easiest source of nitrogen to form nitric oxide is from nitrate or nitrite. Reduction takes place through bacteria from nitrates to nitrites and chemically or through bacteria, nitrites convert to nitric oxide which is the species responsible for linking up with the hem moiety on the meat protein and which then produces the cured colour of cured meat. This is then a bacteria-mediated reduction reaction as opposed to the more difficult microbial oxidation of ammonia to nitrate.”

“It may surprise you that one of the techniques used by ancient horseback riders to cure their meat was to hang strips over the neck of the horse or place it under the saddle for the sweat of the horse to cure the meat. Sweat contains nitrates and the same bacteria that reduce the nitrate to nitrite or that remove the one oxygen atom from the Salpeter to form nitrite is present in horses. Similarly, bacteria that reduce nitrite to nitric oxide are also present on the skin. This would result in the rapid curing of the meat. The fact that meat was placed under the saddles shows the importance of “softening the meat” in a time when people did not have many options in caring for their teeth.” It is the same mechanism, just in a less culturally acceptable way.” I remember accounts that 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.

“German and Austrian cookbooks pre-1600’s 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. Hanging meat around the nacks of horses had a limited lifespan and as the availability of nitrate salts in Europe increased due to its use as a pharmaceutical, for military use and to fertilise fields, the nations of Europe started using it to cure their meat instead of salt only.”

Links Between Turfan and the Black Sea Region

A prominent relationship exists culturally between the people who lived in the Turfan depression and the nations living around the Black Sea. Dr Hans was initially interested in natural mummification and wondered what salt or mineral was in the soil that contributed to this. He discovered the one area on earth where vast nitrate deposits occur on the top layer of soil with records of astonishing ancient technology based on the use of nitrates. Not only are nitrates replete in the basin, but in the surrounding mountains, sal ammoniac is mined and traded into Europe along the northern silk road. Frustrated by not finding strong and surviving meat-curing culture in the area he kept looking, following the silk road to present-day Iran, in the search for the exact location where the horse was domesticated, knowing that cured meat must have become much more important for people who travelled vast distances on horseback. So it happened that he discovered the Scythians.

He long identified that countries around the Black Sea are extraordinary in terms of their meat-curing technology! He learned that the closest nations we have to the ancient Scythians are those living to the east around the Black Sea. Here live people with a level of understanding of meat curing that he has not even found in Germany! Having said that, he re-looked at the ancient links between these nations and Germany and Poland, both giants in the meat-curing world and the influence of Russia.

Russia, along with the nations of Western Europe with their intimate links to the Scythians and their deep understanding of meat curing and rich history in this field made him realise that he is in the right region! All this again feeds back to the western region of China with the Turfan depression as a rich source for ancient curing salts in the form of sal ammoniac and saltpetre!

An Unforgettable Day

It was all over too soon. When Dr Hans was done, everybody applauded! I asked him how he knows so much about meat curing and not only geology and mineralogy. He told me that he grew up in a butcher’s family. His dad had a keen interest in mineralogy in particular since it deals with chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artefacts. His father inspired him to study geology.

That evening we did not read Edward Smith’s book after supper. Instead, we went over the notes I took and where our host was too fast for me to catch everything he said, Minette, helped me to get the facts straight. She has a very keen mind and a great memory.

We talked till very late into the night and all retired to bed, aware that we all experienced something very special today. There were two groups of people that I wanted to share this with. Tristan, Lauren, I could not go to bed without writing this letter. It is now 2:00 a.m.. Tomorrow I will share this with the second group of people or as in this instance, a person. Jeppe could not attend on account of the birthday celebrations of a grandchild. I can hardly wait for Minette and me to share this with him.

Now I am off to bed! I am exhausted but insanely excited! My Danish experience had just gone to another level! I can hardly believe the privilege I have to be here!

Lots of love from Denmark and a very happy father!


Turfan Depression.jpg
Turfan depression

Further Reading

From The Salt Bridge,

01. Salt – 7000 years of meat-curing

02. Nitrate salt’s epic journey: From Turfan in China, through Nepal to North India

03. And then the mummies spoke!

04. The Sal Ammoniac Project

05. An Introduction to the Total Work on Salt, Saltpeter and Sal Ammoniac – Salt before the Agriculture Revolution

06. Ancient plant Curing of Meats

07. The Turfan Depression links with the Black Sea Region


(c) eben van tonder

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Note 1

Neither the University of Copenhagen, the Geology Museum nor any other affiliated organisation had any input in any of the content in this chapter.  All research and conclusions are that of Eben van Tonder and the interaction with the curator of the museum, as portrayed here, is fiction.  Eben places it in this setting for literary and artistic reasons.

Note 2

Hans Thirsten is a reference to Hans Thybo whom we did not meet nor was he ever the curator of the museum. I, however, want to honour Hans Thybo as an exceptional scientist and an unusually talented man by mentioning his name in this work. The entire discussion is based on my own work. To prevent any direct reference to him I changed his surname completely, but I want to mention on whom I base this character. I quote an excellent background of Dr Thybo from Wikipedia which reads:

Hans Thybo (born 19 February 1954) is a Danish geophysicist and geologist. He was a Professor of Geophysics at the Geological Institute and the Institute for Geography and Geology at the University of Copenhagen, as well as at the Centre for Earth Evolution and Dynamics at the University of Oslo. He is a professor at the Eurasia Institute of Earth Sciences at Istanbul Technical University and at the School of Earth Sciences at China University of Geosciences, Wuhan. Until a fusion in 2007 he was elected Head of Department at the Geological Institute and member of the board of Geocenter Copenhagen. He was Professor at Department of Geosciences and Natural Resource Management until he was dismissed from his Chair in 2016. The dismissal was later found illegal and violating employment agreements by an arbitration court and Thybo received a modest economic compensation, but the University of Copenhagen did not re-employ Thybo, nor did the University sanction his accusers. The internationally agreed principle of tenure for university professors does not apply to universities in Denmark. Thybo has earlier been associated with Technische Hogeschool Delft and Stanford University.

Thybo is President of International Lithosphere Program (ILP) og was earlier President for European Geosciences Union, where he also held posts as General Secretary and  President for the Seismology Division. He has been chair for the Danish national committee for ICSU (International Council for Science). He is currently a member of Committee for Freedom and Responsibility in Science of ISC (International Science Council). He is member of and was earlier Vicepresident of Royal Danish Academy of Science and Letters. He has received the 1000 Talents Award from China and he is fellow of Royal Astronomical Society, London and Geological Society of America. He is elected member of Academia Europaea, the Norwegian Academy of Sciences and Letters and Danish Academy of Natural Sciences, and he has been Danish representative to International Council for Science (ICSU).

Hans Thybo has been leader of several geoscientific research programmes and he has been field expedition leader to e.g. the ice sheet in Greenland, east Africa and Siberia. He initiated several pan-European research programmes with east-west collaboration after the end of the cold war. His research includes the discovery of ca. 2 billion year old plate tectonic structures, the fundamental Mid-Lithospheric Discontinuity of the lithospheric mantle, the presence of molten rocks at the Core-Mantle Discontinuity at ca. 3000 km depth below Siberia, a new model for the formation of the economically important sedimentary basins, Presence of strong seismic anisotropy in cratonic crust with the implication that crust and mantle have been coupled for billions of years, and the presence of a hitherto unknown type of crust in Tibet.


All the “Further Reading” articles are my references.

Bacon Curing – A Historical Review

Photo References

Domingos, S. S.. (2011) Vertical flow constructed wetlands for the treatment of inorganic industrial wastewater. Murdoch University WA, Australia.

Featured Image: Bezeklik caves on mountain slopes near Turfan.

Flaming Mountains of Turfan:

McCulloch, John Ramsy. (1845) M’Culloch’s Universal Gazetteer: A Dictionary, Geographical, Statistical, and Historical, of the Various Countries, Places, and Principal Natural Objects in the World.

Turfan Depression: