Nitrate Salts Epic Journey: From Turfan in China, through Nepal to North India
By: Eben van Tonder
25 November 2017
An installment in the series, The Salt Bridge
Also, see Bacon & the Art of Living, also see Chapter 08.06 From the Sea to Turpan
This is the second article in a series that presents a theory that nitrate curing spread from the Tupan/ Turfan region in Western China along the silk and salt trade routes into northern India and Europe. The first article is Salt – 7000 years of meat-curing. In this article, we expand our knowledge of what was happening in Nepal, North India, Western China and the Turfan area in particular in order to develop a better understanding of the salts that originate from the region. India once was the major source of saltpeter to the world and I wondered if meat curing did not originate from India. I start by looking at a very brief history of saltpeter in India pre-colonial and then compare that with saltpeter technology in China and how these validates or contradicts the hypothesis that Turfan is the origin of meat curing. We identify one more ancient salt that probably predates saltpeter as curing salt of choice, that was mined in the Turfan area. In our conclusion, we offer a suggestion on how the massive nitrate deposits of this region may have been used alongside this salt in international trade close to the beginning of the Christian era.
Where were meat curing discovered? The easy answer, given at the introduction of many meat science textbooks is that the origins are lost in antiquity. This will, however, not do. Despite the fact that it was probably discovered at a time before writing, one can deduce a lot by simply looking carefully at history, even at a time when there were very few or no written records and when preserving meat was not a topic to waste the revolutionary new invention of writing on. Whether we will exactly discover the answers we are looking for is not as interesting as the quest itself of trying to find it. Like Odesious’ Odessy, in this instance, the journey is the end in itself.
It is remarkable how much one learns by looking into the past. I became intimately familiar with chemicals which I only knew vaguely and processes that I could not have imagined; I learn about mystical and enigmatic lands and cultures, many of whom endure to this day and I learn to be better at meat curing.
My basic thesis leading to the journey is that nitrate salt’s use in food as preservative originated in the Turpan region in Western China, also called Turfan or Tulufan. According to this hypothesis, it is therefore also the birthplace of meat curing. The article where I first set this out is Salt – 7000 years of meat-curing. With no understanding of the complex nature of the history of this region and the salts found on its shores, I set out to learn. I learned that saltpetre was by no means the oldest salt used in meat curing.
Sherlock Holmes said in The Hound of the Baskervilles, “the world is full of obvious things which nobody by any chance ever observes.” People fail to observe, not because they are lazy or disinterested, but because observing in itself carries risk and is damn hard work. More than that, it is one of the greatest journeys on earth filled with ideas, energy, hope, intrigue, mystery, romance and sometimes even success.
The Land of Aryvarte
A bizarre coming together of random events and the actions of Tristan meant that I would be in the land of the Aryvarte, in the birth land of the Buddha. Minette, Tristan, Sabin and Duan were set to do the Mardi Himal Base Camp hike as our first introduction to the Himalayas. What I completely underestimated . . . well, I underestimated everything, including Nepal itself, its people, its food, its history and its salt!
The country is land-locked between Tibet to the north and northern India to the south. I was definitely in the right region as one of the silk road routes skirts the Turpan region before running south through Tibet and Kathmandu into North India. Nepal is located in the ancient land called Aryavarta, “or the abode of the Aryana”. Manu, the ancient law-giver applies the name to the tract of land between the Himalaya and Vindhya ranges; from the eastern to the western seas.” Later on, the entire region from the Himalayas to Cape Comorin, “and from the Irawady and the Bay of Bengal to the Indus and the Western sea, came to be recognised as Aryvarte.” (Bhagvat Sinh Jee, H. H., reprint 1998: 13) I was here. In this exact place.
The Aryvarte was inhabited by a unique people, the Hindu. These people, like their neighbours are some of the most impressive on earth. Their intellectual, cultural and spiritual heritage impressive in every sense of the word. Their astronomical knowledge date back to 3000 years BCE. In mathematics, they invented the decimal and the numerical system, geometry and trigonometry. They had a formal understanding of grammar and philosophy with a well developed legal system. In terms of architecture, they were unrivaled from the earliest times. In chemistry, they had considerable knowledge and Bhagvat Sinh Jee credits the Hindu’s of this land with “knowledge of the preparation of sulphuric, nitric and muriatic acids; the oxides of copper iron, led, tin, and zinc; as well as many chlorides, nitrates, sulphates, and carbonates.” The compendium of knowledge that contains these ancient traditions and teachings is called the Veda (knowledge), from Sanskrit vid, to know.
The Veda, it is believed, is the revealed knowledge of the creator. They believe that knowledge is acquired and not created, and if this was not so, instruction would be futile. The discovered knowledge is handed down from father to son and teacher to student. Four Vedas have been developed. Rig Veda, Yajur Veda, Sama Veda, and Atharva Veda. The Brahmans are the custodians of the sacred tradition. (Bhagvat Sinh Jee, H. H., reprint 1998: 13-19) The Vedic period spans the mid 2nd to mid 1st millennium BCE with Witzel suggesting the possibility of written Vedic texts towards the end of 1st millennium BCE (Witzel, M) with others opting for a much earlier date.
These dates are important since, in their writing, they speak about various mineral salts, including saltpeter. My question is how old these references are to try and see how widespread the use and trade in saltpeter was.
The Discovery of a Lifetime
As soon as I gave my first step on Nepali soil, I realised that my entire world and experience as a human were about to change as I entered a land, unlike any I have ever been to. The beginning of human history is felt in the air. Unpretentious and honest with no desire to debate any misplaced notions. Like the Himalayan mountains itself which dwarfs every natural wonder experience without trying to do so; in the same way, the air one breaths fill you with certainty that here a higher wisdom resides which existed from the beginning of time. Every person is a sage and every human encounter, no matter how mundane, completely educational.
I was unprepared for the trip and yet, in a strange way, life prepared me for months and years for this. Back in Cape Town, before I boarded the plain, I got myself an ebook version of the 1902 book by Praphulla Chandra Ray, D. Sc., A History of Hindu Chemistry from the earliest time to the middle of the sixteenth century A.D.
A few months ago I became acquainted with the monumental works of the Chinese scholar Needham, Science and Civilisation in China. I had it on my phone. Both his 1959 volume 3 subtitled, Mathematics and the Sciences of the Heavens and the Earth and his 1980 volume 5, with the sub-title Chemical and Chemical Technology. I also recently acquired the landmark work by Berthold Laufer, Sino-Iranica, Chinese Contributions to the History of Civilisation in Ancient Iran, published in 1919.
Before we left Cape Town, I worked a few days 16-hour shifts at Woody’s to put things in place to enable me to leave. Upon my arrival in the classical hotel setting of the in Dalai-la Boutique Hotel, Kathmandu, my body was so used to the 16 hours work shifts that I found myself passing the time from 24:00 to 07:00 when my compatriots started waking, flip-flopping between the works Ray on the chemistry heritage of the Hindu, Needhams almost superhuman thoroughness in tracing the development of the sciences in China and Laufer’s mesmerising and romantic world of Western China, Tibet and Iran.
My subject matter was the salt of the earth, flavours and taste notes. This deep fusion of spices has only ever been achieved in this region and I believe, the origins of our art of meat curing. Earlier this year I developed a hunch that meat curing was developed into the universal art it is today beginning in this general region, focussing on the Turpan area in western China. Being in Nepal put me in the perfect location to develop the thoughts further.
The Problem of Terminology
I was still working on the assumption that saltpeter was the original curing salt and that the ancient history of this salt and meat preservation are the key to understanding the ancient origins of meat curing. This, I soon discovered, was a wrong assumption, but before I realised this, I ran into a problem with terminology. What did the ancients call potassium, sodium, magnesium or calcium nitrate salts?
Bhagvat Sinh Jee lists the following principal salts as important in ancient medical traditions from this region. He made his list in 1896, looking back at the ancient compound chemicals. He lists Navasadara (chloride of ammonia), Sindhava (chloride of sodium), Pamshujakshara (carbonate of potassium), Yavakshara (carbonate of soda) and Suryakshara (nitrate of potash). I, however, do not know how old these references are or the exact quotes or reference. The lists he gives in his work, A short history of Aryan medical science, published in 1896 (Bhagvat Sinh Jee, H. H., reprint 1998: 136) is very interesting. He mentions nitrate of potash (Suryakshara). Potash is, of course, the origins of the word “potassium” and nitrate of potassium would be potassium nitrate or saltpeter. Here I have what I am looking for, but how far do his references go back for the use of the word suyakshara. I wanted to see how far other authors traced the use of the word back. What I completely missed, was the first compound mentioned by him namely navasadara or chloride ammonia. How important this was in the history of meat curing only dawned on me as the time in Nepal went by.
Back to my search for ancient references to saltpetre, Joseph Needham, in his 1980 publication of volume 5 of Science and Civilisation in China, on Chemistry and Chemical Technology quote the Hoovers who wrote that if one looks at the properties of what was called saltpeter in antiquity, it was “mostly soda, more rarely potash, and sometimes both mixed with common salt.” They stated that if one would try and write a book on all the ancient uses of the word, it would be composed of many volumes and that very early on no single clear definition of saltpeter existed. (Needham, J.; 1980: 179)
Needham gives a good example of the origins of the word nitre and how this was later confused with saltpetre. He quotes Jeremiah who wrote: ‘Though thou wash thee with nitre and soap, yet thine iniquity is marked before me, saith the Lord’ and the Old Testament book of Proverbs which reads, “Confidence in an unfaithful man in time of trouble is like a broken tooth, or a foot out of joint; As one that casteth off garments in winter, or as vinegar upon nitre, So is he that singeth songs to a heavy heart.”
Needham comments, that since the “detergent effervesced with acid, and indeed sodium carbonate it was. This salt occurs naturally, mixed with some bicarbonate, as well as the chloride (2 to 57 %) and the sulphate (1 to 70%), in parts of the Egyptian desert, notably the Wadi Natrun where there is a succession of salt lakes annually inundated, and has been gathered, purified and used for thousands of years. The proper name for it was natron, a word derived from the ancient Egyptian ntry, hence our modern symbol for sodium; but by assimilation with Gk. nizo and nizomai, to wash, ‘nitre’ resulted, via Gk. nitron and Lat. nitrum. From the IVth Dynasty onwards (c. 2900 BCE) natron was used, never salt, for that desiccation which was the essential process in mummification, being regarded too as a great cleanser, destroying all fat and grease. But it was also used in many industrial arts, such as those of incense, glass-making and the bleaching of cloth. Nitre continued to have this meaning as late as Agricola, but from the beginning of the + 14th century onwards it was applied also to saltpetre – understandably enough, perhaps, since all these salts were collected from incrustations on the ground. Hence much confusion, even throughout the + 17th century, when saltpetre was often called sal nitri.” (Needham, J.; 1980: 180)
The ancient use of the word nitre, meaning sodium carbonate or sodium bicarbonate and the confusion that it creates is nowhere clearer than in the reference of Pliny the Elder to the accidental discovery of glassmaking, reportedly 5000 BCE in the north of Israel, south of Lebanon. The story is not beleived to be historically accurate, but the use of the word nitre is instructive.
“In Syria there is a region known as Phœnice, adjoining to Judæa, and enclosing, between the lower ridges of Mount Carmelus, a marshy district known by the name of Cendebia. In this district, it is supposed, rises the river Belus, which, after a course of ﬁve miles, empties itself into the sea near the colony of Ptolemaïs. The tide of this river is sluggish, and the water unwholesome to drink, but held sacred for the observance of certain religious ceremonials. Full of slimy deposits, and very deep, it is only at the reﬂux of the tide that the river discloses its sands; which, agitated by the waves, separate themselves from their impurities, and so become cleansed. It is generally thought that it is the acridity of the sea-water that has this purgative effect upon the sand, and that without this action no use could be made of it. The shore upon which this sand is gathered is not more than half a mile in extent; and yet, for many ages, this was the only spot that afforded the material for making glass.” (Natural History)
“The story is, that a ship, laden with nitre, being moored upon this spot, the merchants, while preparing their repast upon the sea-shore, ﬁnding no stones at hand for supporting their cauldrons, employed for the purpose some lumps of nitre which they had taken from the vessel. Upon its being subjected to the action of the ﬁre, in combination with the sand of the sea-shore, they beheld transparent streams ﬂowing forth of a liquid hitherto unknown: this, it is said, was the origin of glass.” (Natural History) When Hippocrates in the ﬁfth century BCE used the Greek word ‘nitron’ and the Latin ‘nitrum’ of Pliny in the ﬁrst century CE with the English equivalent of ‘nitre’, all these refer to soda obtained from either evaporitic lakes or plant ash (Turner WES, 1956) and not to saltpeter. The association of nitre with saltpeter only came in the last few hundred years.
Needham’s comment that “all these salts were collected from incrustations on the ground” is key in the consideration of meat curing. My point is that if these “incrustations on the ground” contained nitrate salts and if these were the salts used from as early on as humans inhabited these regions where natural nitrate deposits are found then the very observant ancient cultures would have noticed it. This is, in fact, the start of science itself in China, for the Hindu and in the west – natural observations. What words were used for it and how it was categorised naturally started very broad and uncertain, but I have little doubt that the ancients knew that if salt from encrustations on a particular ground is applied to meat, the meat lasts longer (done in the context of a desert environment where food was scarce and distances challenging to cross even by modern standards); that the meat seems to come back to life by changing to a “living” reddish colour; and, I am equally sure that the distict taste of cured meat did not escape their notice despite the fact that it was the ancient Greeks who first wrote about it.
Ray, dealing with the use of the words for saltpeter in Sanskrit, writes that “the very word [Saltpeter] is conspicuously absent in the literature of the ancients.” The two words that were used for saltpeter in the Sanskrit languages were sanvarchala and yavakshara, both referring to nitrate of potash. Later, in Sanskrit, in the Sukraniti and in the Rasarnava, the word translated saltpeter is sauvarchala. He says that it is “very remarkable that in the late Sanskrit chemico-medical literature [this word] ceased altogether to be applied to it (saltpeter)”. It was later used as a synonym for sarjika (natron). Instead, the word yavakshara were used, despite the fact that from the time of Charaka and Susruta this word has been used to refer to the ash of barley (impure carbonate of potash; from yava, barley and kshara, ashes). A number of dictionaries therefore wrongly translate yavakshara as saltpeter. (Ray, P. C., 1902: 99 – 100) He does not mention Bhagvat Sinh Jee’s suyakshara (potassium nitrate).
Saltpetre works from Ancient North India
The names used for saltpeter was not clear and one had to look at the context of each reference to determine what salt exactly the ancients were talking about. I was wondered if the saltpeter works in North India held any clue. Were they trying to refine something they saw from the Turfan area or did the technology of refining saltpeter develop independently from the natural deposits found in West China?
A group was set up by the Middelaldercentret (Medieval Centre), Nykøbing Falster and the University of Leeds namely the “Medieval Gunpowder Research Group” who set out to make and test gunpowder made from ingredients produced as closely as possible using methods of the medieval or early modern periods. Their reports are fascinating and are all available on the internet. The following information is from their Medieval Gunpowder Research Group Report6.
They visited north India to get a first-hand account of how saltpeter is collected from the soil. In their report 6, they deal with possible origins of the nitrate deposits in North India. From their visit to the region, they report that the “saltpetre soil was collected in the months of March and April. This was somewhat surprising as the sources indicate that it was collected at the end of the rainy season which finishes in September. They further learned that the process of collecting the soil and carrying out the extraction and first, crude, purification was carried out by a group of itinerant workers, from Bihar, who arrived each year in March and April. The area where they collect the saltpetre varies from year to year and we were taken to, and collected samples from, an area that had been exploited in 2004.”
“A possible reason why the soil is collected in March and April may relate to the process by which the saltpetre comes to the surface. From June to September much of India is subjected to the monsoon rains in which the ground becomes highly saturated. The water will penetrate deep into the ground dissolving salts as it does so. When the rains stop the ground starts to dry out and as the water evaporates from the surface, it will draw, by capillary action, the water deep in the soil to the surface, carrying the soluble salts with it. This drying process would seem to take several months with the most salts, including the saltpetre, collecting at the surface when the ground is driest – in March and April – and before the next rainy season. What was also surprising was that no source of potassium, for example, potash, was added during the process but that the end result was potassium nitrate – one would expect calcium salts to predominate.”
Why is this such an important question? It has been known since the groundbreaking work of Müntz and Schlössing in 1877 that bacteria are responsible for the oxidation of ammonia and amonium to nitrite and nitrite to nitrate. Sergei Winogradsky (1856 – 1953) became the first person early in 1890 to isolate bacteria that reduce (ammonia) to (nitrite) (Nitrosomonas and Nitrosocococcus) and found that bacteria of the genus Nitrobacter oxidizes nitrite to nitrate. This formidable scientist showed that these organisms use the energy released from nitrification to drive their metabolisms. (Lodders, K. and Fegley, B. Jr.; 2011: 376) When organic matter is broken down during decomposition by these microbes, predominantly calcium and magnesium nitrates are produced as waste product. This means that saltpeter from such decomposition starts life as either calcium or magnesium nitrate.
Saltpeter is then created from these. The first printed work in the West on metallurgy, De la pirotechnia, written by the Italian Vannoccio Biringuccio and published in Venice, sets these steps as mixing the nitrate salts in water with quick-lime and wood ash. The nitrates react with the potash ( forms from the wood ash) in an alkaline solution to form two highly insoluble salts, calcium carbonate (limestone: ) and magnesium carbonate (mahnesite: ). This leaves saltpeter or potassium nitrate in solution.
This question of the origin of the potassium in the North Indian saltpeter “was discussed with Professor Rajiv Singha of IIT-Kanpur who believes that the answer may be that the area is fed by rivers that run through areas rich in potassium salts. But this does not answer the question of where the nitrate comes from. It is not a naturally occurring salt and is produced by the reaction of bacteria with area and ammonia compounds in animal waste, particularly urine. Was the source of the nitrate here also from this process or were there other factors at work? A possible explanation is that the very high population, of both people and animals, has over a very long period, possibly millennia, produced a high level of nitrate in the soil and this is still coming to the surface.”
The process of collecting and refining saltpeter in this region is ancient. The question now comes up what the ancients called the saltpeter soil. Ray writes that “it is strange indeed that a substance which occurs exclusively in Bengal and in upper India as an efflorescence on the soil should have been allowed to go without a definite name for several centuries.” He then quotes Dutt who said that “nitre was unknown to the ancient Hindus. There is no recognised name for it in Sanskrit.” (Ray, P. C., 1902: 100) He continues that in his time there were “some recent Sanskrit formulas for the preparation of mineral acids containing nitre” where this salt is referred by the name soraka. “This word, however, is not met with in any Sanskrit dictionary and is evidently Sanskritized from the vernacular sora, a term of foreign origin.” (Ray, P. C., 1902: 99 – 100)
I speculate that they used the salt in an unrefined form for millennia for various industrial and medical uses. I have not reviewed the climate history of the region but the current climate lacks the incentive for the development of meat curing which suits desert conditions better where hunters, nomads, and traders had to travel vast distances without any hope of finding food. I would speculate that preservation was probably the first incentive for using these salts with the ability to change the meat colour back to a healthy reddish colour as a secondary importance. This again points to the Turpan area as the birthplace of meat curing and not North India where the development of saltpeter technology was later than in China.
Ray makes the same point when he says that “the manufacture of nitre was, therefore, most probably introduced into India after the adoption of gunpowder as an implement of war.” (Ray, P. C., 1902: 99 – 100) I am interested to know when this was and decided to review the chronology. According to Frey, the watershed time for India between the age of the blade and the age of the gun came in the early sixteenth century.
He states that “it is likely that Mongols who introduced the making of fireworks to India in the mid-thirteenth century. We know almost nothing about saltpeter production during this early period, but technical expertise apparently diffused with the adoption of rocketry and eventually artillery by Indian rulers in the fourteenth century. The break-up of the Delhi Sultanate, the rise of regional states, and the growing presence of Turkish mercenaries in India may be linked to the establishment of regular saltpeter production and the adoption and use of gunpowder weapons.” (Frey, J. W.; 2009: 512)
“By the fifteenth century, Indian rulers began to acquire significant parks of artillery, and direct references to saltpeter production suddenly surface, especially in Bengal and neighboring Jaunpur, sultanates dominated at the time by Afghan warlords. Two Persian dictionaries of the period, written by court scholars from these regional states, describe saltpeter manufacturing in detail. These references are telling because the area lying between Jaunpur and Bengal eventually emerged as the premiere saltpeter-producing region of India. As early as the 1460s, nearly forty years before the commencement of the East India trade, these Persian sources make it clear that the rulers of Jaunpur and Bengal already had organized production as state monopolies managed by their chief merchants. (Frey, J. W.; 2009: 512, 513)
Abu’l-Fath Jalal-ud-din Muhammad Akbar, known as Akbar I and later as Akbar the Great, became the third Mughal emperor, who reigned from 1556 to 1605. His land included what is today known as north India. He made effective use of gunpowder which by the mid 16th century became widely available. Fey writes “we do not know precisely how Akbar’s army acquired gunpowder, but the importance of saltpeter was understood by the Mughals, who demonstrated an interest in the technical aspects of its production and use. Significantly, the saltpeter grounds of Bihar are not mentioned by Abu al-Fazal, although they certainly existed in Akbar’s time. The general impression given by the A’in-i Akbari is that possession of firearms and powder manufacturing were decentralized, at least in Akbar’s empire.” (Frey, J. W.; 2009: 517)
Sher Shah Suri (1486–1545), the founder of the Sur Empire in North India, with its capital at Delhi ruled the empire from 1540 to 16545 over which Akbar ruled and made widespread use of gunpowder. In a way, Akbar only followed in his footsteps and progressed technology and tactics that was introduced by Sher Shah Suri in the 5 short years of his rule. Interestingly enough, it was a gunpowder explosion that ended Suri’s life in 1545. During his time the state was even less involved in gunpowder production and he ordered local officials to “purchase from local bazaars at current prices.” (Frey, J. W.; 2009: 517)
This is a statement that fascinates. “Purchase from local bazaars at current prices“. We have the “adoption of rocketry and eventually artillery by Indian rulers” associated with the establishment of regular saltpeter production and the adoption and use of gunpowder weapons in the fourteenth century. By 1540, gunpowder, and presumably saltpeter was so common in north India that officials were ordered to purchase it from local bazaars, al current prices. The transition years, therefore, as far as north India is concerned seems to be the 250 years between 1300 and 1540.
Why is this important? Lets for a moment forget about the question if meat preservation was necessary for north India. If saltpeter was the curing agent of choice in any area, it had to be available and if curing spread from this region, surely the salt used in curing had to be traded under a specific name. The military demand undoubtedly increased saltpeters general availability even though, at times of war, it would certainly also have restricted its availability as it did during the First World War which resulted in the change from saltpeter to sodium nitrite in meat curing. This, however, only happened in India between the years 1300 and 1540.
Gunpowder came from China
Gunpowder was invented in China. “The oldest mentions of gunpowder in Europe are all unquestionably of the late + 13th century, preceding its general introduction in the + 14th. In China, on the other hand, we have the first reference to the gunpowder mixture in the + 8th or + 9th century, its appearance in war early in the + l0th, and its widespread military use in the + 11th and + 12th before it reached Islam and Europe in the + 13th.” (Needham, J.. 1980: 195) The oldest reference to a proto gunpowder mixture comes to us from c. 850 in the Chen Yuan Miao Tao Yao Lueh where there is a test for saltpetre. (Needham, J.. 1980: 187) This means that saltpeter related technology was already mentioned in China, 450 years before it developed in India. This, in turn, seems to support the notion that meat curing developed in regions closer to China or in China itself.
A side comment is in order here. Reviewing the evidence from China makes it clear that Chinese alchemists of the 8th and 9th century were able to distinguish between potassium nitrate and other alkali metals for the purpose of gunpowder production. My question is if the average salt trader or the general public had this ability which they most certainly did not possess. This means that an exact and accurate description of every salt sold in the markets and pharmacies of the day was a dubious affair at best.
Up to this point, we have seen that the world leader in saltpeter related technology was China with records dating back to 850 BCE. Despite ancient references to it in Hindu literature and the fact that it occurs in North India, the identification, analysis, and application of technology related to nitrate salts were first done in China and not India. Or so it would seem. There is an interesting story that Needham recount which may show that mineral acids, such as nitric acid were known in both India and in China by the 7th century. We will return to this in a subsequent article. Needham tells it in section (3) Saltpetre and copperas as limiting factors in east and west. (Needham, J.. 1980: 195) Still, it would seem that the clear mention to saltpeter in China, predates any other.
Tracing References to Saltpeter in Chinese Records
Needham writes that “the ‘nitre’ complex, too, is simply one typical example of the difficulty of identifying the substances used by the medieval alchemists and pharmacists. The most helpful signs to go by are always the descriptions of the properties of the substance concerned mentioned in any given Chinese text. Thus of hsiao shih (which goes back as a name to the – 4th century) it is often later said that it gives a bluish-purple flame when put in the fire, a statement which immediately rules out salts of sodium and magnesium.” (Needham, J.. 1980: 193, 194)
“The oldest description of this test comes from about + 500, but it could safely be placed a couple of centuries earlier, as far back as Ko Hung. Many alchemical and pharmaceutical texts from the – 2nd century onwards also say that hsiao shik can liquefy ores, acting as a fluxt and dissolve minerals to form aqueous solutions. There are also instances where hsiao shik is said to produce explosions or deflagrations, and we have of course the gunpowder formulae with hsiao shih in them. In such circumstances one can feel fully justified in extrapolating back the results of analyses ·of modern samples of hsiaosmh which show it to be saltpetre.” (Needham, J.. 1980: 193, 194)
Rightly therefore was it called in Arabic, Chinese snow, for it was recognised and used in China long before anywhereelse. The oldest extant Arabic mention is in the Kitiib al-Jiimi’ fi al-Adwiya al-M.ufrilda (Book of the Assembly of Medical Simples) finished by Abti Muhammad al-Mllaqi Ibn al-Baitarg about + 1240. Others follow shortly after. (Needham, J.. 1980: 193, 194)
A Fascinating 1871/ 1872 Mention of Meat Curing with Salts from Turpan
This being the case, what preceded the use of saltpeter as curing salt? In a region where nitrate salts naturally occur, it is easy to see that it was used for preserving meat. It would be a mixture of various salts among whom there would have been nitrate salts. We are however not investigating a claim that it was used as curing agent locally in the Tarim region, but if this was where curing developed in a way which spread across the world. For this to be the case, the salt in question must have had a particular name and there must be references that it was traded.
We can ask the question like this: Was it a “luck of the draw” if salt bought at the market may or may not have contained nitrates or could the client ask for a particular salt. If saltpeter’s use only gained momentum parallel to its inclusion in the production of gunpowder, was there another salt from ancient times or another name for salts used that could cure meat? One would expect such a salt to have a specific name and evidence of it being traded.
An ebook from 1871/1872, Pharmaceutical Journal: A Weekly Record of Pharmacy and Allied Sciences, Volume II, published by J and A Churchill from London yielded an unexpected nugget. It quotes another work entitled Contribution towards the material medica and natural history of China, for the use of medical missionaries and native medical students. The author is Frederick Porter Smith who refers to himself as a medical missionary to central China. He writes that the work is the result of two years of leisure spent in the city of Hankow. He listed different substances found in the drug shops of the Chinese and in dispensaries attached to the mission hospitals. He lists the product and gives a short history and use of each article.
The substance listed as an example of his work is on Sal Ammoniac. At first, I am disappointed that they don’t list saltpeter, but as I look deeper into this salt of Ammon, I realise that I have just found the kind of alternative curing salt I was looking for whose popularity predates saltpeter. My focus on saltpeter was valuable to bring curing in the 1700’s and 1800’s in Europe into perspective, but this was by no means the only salt known from antiquity that contained nitrogen. Nor was it the most well known.
I realise that in the many works on saltpeter which are almost exclusively dedicated to the development of gunpowder, of course, the focus must be on the nitrate salts. Here you need the three oxygen atoms to provide the explosive power which is found only in nitrate. Nitrate is valuable in meat curing not in and of itself, but in that it is changed into nitrite when it loses one oxygen atom through bacterial action. Nitrite is the starting point of chemical reaction sequences which end up in nitric oxide formation which cures the meat. This is true but what I failed to seriously consider is that ammonium is also changed into nitrite through bacterial metabolism, just like nitrate. In the case of ammonium, two oxygen atoms are added to form nitrite.
The reason why I never seriously considered it was that I failed to appreciate the universal occurrence of sal ammoniac and thought it was restricted to regions in Egypt. Nor did I have any inkling of the massive trade that was done in this salt.
Let’s get back to Smith’s work and I quote the example he gives namely his entry on Sal Ammoniac. He writes, “Nau-sha, Nung-sha, Peh-ting-sha – this saline substance, the chloride of ammonium of chemists, is brought from Lan-chau-fu and Ning-hia in Kan-suh. The country of the Tih, or Si-jung and Turfan formerly yielded it. The volcanic mountain of Peh-ting in Turfan is said to have yielded some ammoniacal salt from fissures in its sides, and hence the name Peh-ting-sha, more correctly given to volcanic ammonia. The Chinese name Nau-sha is very like the Hindustani name Naushadar or Nausadar, given to thick, fibrous translucent cakes of the crude salt of ammonia obtained in India from the unburnt extremity of brick-kilns in which the manure of camels etc. is used as fuel. (Dr. Waring’s Ph. of India, p. 309) Keferstein affirms that both carbonate and muriate of ammonia are found in China, but the dirty-white, rough, deliquescent salt commonly sold under this name is nothing but sulphate of soda or common salt. Nitro (soda-nitrate) and borax are also confounded with it. It is used as a flux or solder, or is said to be so employed. Whilst the salt is said to be deleterious, it is also said to be used in curing meat, or as a condiment. It is mainly used as a solvent for opacities of the cornea, for which the sulphate of soda acts almost as well. It acts as a sedative, resolvent, deobstruent, pectoral and mild escharotie, in Chinese estimation. They use it in veterinary practice. Some of the samples contain iron and resemble the Kala Nimuk of India. ”
So, from the same region we now know that not only is it replete with nitrate salts, but due to volcanic activity, the famous salt from Egypt, sal ammoniac is found. I have little doubt that the information about the Smith’s reference of the “volcanic mountain of Peh-ting in Turfan is said to have yielded some ammoniacal salt from fissures in its sides” comes from the work of none other than Alexander von Humboldt (1850; Views of Nature). He almost quotes Humboldt verbatim. As Smith states, this was a time when different salts were easily confused and the mention of meat curing with sal ammoniac is of particular interest.
It occurred to me that Sal ammonia may have been the forerunner of saltpeter 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 result. Reaction Sequence
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 taste like since it was added to my favourite Dutch candy “Zoute Drop” with licorice. I believe it was none other than my old friend, Jan Bernardo who first gave me Zoute Drop. As a boy, I used to ride my bicycle once a month to the only Greek Caffe in Vanderbijlpark which sold it for my monthly fix. My favourite was the double strength version called “Dubbel Zoute Drop.”
Smith states that mistaken identifications were commonplace. He said that “nitro (soda-nitrate) and borax are also confounded with it.” Nitro is, of course, the salt that we are more familiar with for meat curing and this region contains one of the largest natural nitrate deposits on earth.
The fact that sal ammoniac was confused with sodium nitrate is interesting. In order to evaluate this statement, we have to understand how the massive nitrate deposits in this region came about. Atmospheric nitrate finds its way to earth through a process which we call the nitrogen cycle and is the main way the earth fertilises itself. It almost never “accumulates” in vast reservoirs, especially not in the open land due to its high solubility. Water dissolves it and carries it into the soil where plants use it as fertiliser and bacteria use it in their metabolism, producing a new compound with a different oxidation state.
It is known to accumulate in a few regions on earth. Two factors are responsible for this namely age and the dryness of the region. The Turpan-Hami area is one of driest regions on earth with average annual rainfall of 15mm and “intense evaporation often times 200 times the rate of rainfall.” On top of this, there is little surface vegetation which would, of course, use the nitrates as nutrition coupled with the occurrence of strong north-west winds which would dispell any surface precipitation. (Yan Qin, et al, 2012) The result in regions like this is atmospheric nitrogen build-up in the form of nitrates.
Nitrate deposits are widely distributed in the area (Yan Qin, et al, 2012) and the amount of nitrate in the Turpan-Hami basin is estimated at 250 million metric tones which rival those of the famous Atacama nitrate deposits (Wensheng, G. E., et al, 2014). The most common nitrate deposits are found in the top 50cm of the surface layer towards the center of the basins, particularly in the Turpan basin (this is in contrast to the Atacama deposits which occurs deeper down). Its origin has conclusively been demonstrated to be from the atmosphere. (Yan Qin, et al, 2012)
The soil, however, never contains only nitrate. It is a rich mixture of different minerals and in the Turpan-Hami basin, it is particularly interesting since it is naturally engineered to contain not only nitrates but a rich mixture of minerals ideally suited for meat preservation. The soil is a mixture of nitratine, the natural form of sodium nitrate; halite, which is the mineral name for salt or sodium chloride, or rock salt; and mirabilite or Glauber’s salt which is a hydrated form of sodium sulfate. The nitrate composition ranges from between 2% and 27.98% of the ore tested and average at 10% in the 2012 study by Wensheng, G. E. and coworkers. Halite or sodium chloride was at an average of 30%, darapskite, a crystalized rare mineral which is chemically a water-containing sodium nitrate sulfate, at 20%, nitratite or sodium nitrate at 10%, and thenardite, an anhydrous sodium sulfate mineral (Na2SO4), anhydrite, an anhydrous calcium sulfate mineral, CaSO4, bassanite, a calcium sulfate mineral with formula CaSO4·0.5(H2O) or 2CaSO4·H2O, and glauberite, a monoclinic sodium calcium sulfate mineral with the formula Na2Ca(SO4)2, at an average of 3 -8%. (Wensheng, G. E., et al, 2014). From these, it is easy to see how, if the rocks containing these minerals were crushed and applied to meat, it acts as a powerful preservative due to the presence of the three key elements used in food preservation to this day namely nitrate, sulphate and chloride.
But what about Smith’s sal ammoniac which was confused with nitro (soda-nitrate). It is unlikely that the sal ammoniac mined from the fissures from the sides of the volcanic mountain of Peh-ting in Turfan was mixed with the massive nitrate deposits of the region. Yan Qin, et al (2012) reports that “signiﬁcant nitrate deposits are only found at least ~15 km away from foothills” which rules out accidental contamination when the sal ammoniac was mined. The answer shows that pure sal ammoniac had nothing to do with the massive nitrate deposits and introduces us to another one of the many ammonia salts. Of course, sal ammoniac almost never riched its destination in Eastern China and Europe as a crystal, but due to moisture, as looking similar to other incrustations on the ground.
Lets look a bit closer at the characteristic of sal ammoniac. Several minerals exist composed of ammonium (NH4). Ammonium is formed by the protonation of ammonia (NH3) . Sal Ammoniac is the most well known and was named by the ancient Romans. They collected this salt which was found around the temple of Jupiter Ammon in Egypt and called it salt (sal) of Ammon (ammonocius). The name ammonia was subsequently derived from it. It forms in volcanic vents and after volcanic eruptions before it has rained which dissolves it. 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.
Ammonium readily combines with an acid thus forming a salt such as hydrochloric acid to form ammonium chloride (sal-ammoniac) and with nitric acid to form ammonium nitrate. Recent studies have shown that volcanos release a “previously unconsidered flux of nitric acid vapour to the atmosphere. (Mather, T. A., et al, 2004) Of course, whether this is the nitro that Smith refers to is only speculation, but what is a fact is that the Turfan area, both the basin and the mountains is replete with different salts containing nitrogen (nitrate salts and ammonium) any one of which could be used effectively in meat curing.
Trading Sal Ammoniac
The one key component was still missing namely evidence of a large-scale and “universal” trade in this salt, possibly even on a scale that set it apart from saltpeter or any other salt.
An unexpected surprise emerged from the work of Valerie Hansen and the area where the records were compiled is none other than from ancient Turfan itself. Turfan (Turpan) is located on the northern route around the Taklimakan desert and forms a bridge between the Chinese and Iranian worlds. Valerie Hansen, in her brilliant work on the silk road (The Silk Road: A New History), describes the current day cosmopolitan feel which the city probably always had. “Vendors on every corner sells naan, the leavened flatbread like that is eaten in central Asia and North India. At a conference, I attended there in the mid-1990’s, a Norwegian professor of Iranian languages cheerfully greeted everyone at breakfast, explaining that it was the first time he had woken up to the sound of braying donkeys since being in Iran before the 1979 revolution. In town, one sees many Uighur and Chinese faces, and the proprietors at the bazaar – even Chinese speakers say “baza’er” and not the Chinese word for “market” – proffer rugs, glistening jeweled knives, and always a glass of tea to potential customers.” (Hansen, V.; 2012)
Historically Turfan comprised of mainly two peoples, Chinese and Sogdiana, from the region around Samarkand, the oldest inhabited city on earth dating back to the 8th or 7th century BCE, located on the Silk Road and linking China and the Mediterranean. The Han dynasty fell in 220 AD and large numbers of Chinese migrated to the northwest. Turfan and Kucha were the largest two settlements on the northern route around the Taklimakan. The Sogdians felt that Turfan was so Chinese that they referred to it as Chinatown.
There was a practice in Turfan that unwittingly gave us a remarkable record of their society. They recycled paper that was written on by using it to make shoes, belts, hats, and clothing for the dead. The source material is therefore random and unedited by someone who wants to bring his or her own particular message across. Chinese in other regions had the same practice, but it was here in Turfan where conditions were best for preservation due to the low humidity. The lowest region in Turfan is 154m below sea level, the second lowest point on earth, after the Dead Sea. Turfan is dry and hot and the Chinese referred to it as the prefecture of fire. Summer temperatures reach 60 deg C. (Hansen, V.; 2012)
The southern silk route fell into disuse in 500 AD and many travelers opted for the northern route through Turfan. By 640 AD, a census listed the number of people living in Turfan as 37 700 and 8000 households. Hundred years later, the number of households increased to 11 647. The city was one of significance and documents from the gravesites in the area offers a unique insight into life on the silk road. (Hansen, V.; 2012)
The first fragment of interest in our quest shows the close contact between the people from the region. This fragment from 477 lists expenses for hosting envoys from “the Rouran people of central Asia (known in Europe as the Avars, a nomadic people), the Karghalik kingdom on the southern edge of the Tarim basin; the Song dynasty (420 – 479) whose capital was in Nanjing, China; the Uddyana kingdom in north India, and the “Brahman country,” most likely a reference to South India.” This shows us some of the neighbours that Turfan maintained diplomatic relations, but trading extended to others also. Coins and documents show trading relations with Iran, especially the eastern Iranian world of Samarkand which was their most important trading partner of the first independent Goachang Kingdom and not Rome, as one may expect. (Hansen, V.; 2012) This city will become very important in our discussion on sal ammoniac. Later, after 640, the most important trading partner was Tang China. (Hansen, V.; 2012)
Many of the Sogdians lived in Turfan. Around 600 AD, Gaochang officials recorded the names of 48 merchants who paid tax on goods they sold to each other. These documents survived in 10 paper shoe soles cut from four sections of the register, recorded over a year. This is the single most important document offering us information on the commodities traded on the silk road. (Hansen, V.; 2012)
The first valuable bit of information is not the commodities itself, but the importance that Sogdians played in the Silk Road trading. Of the 48 names listed, either as buyer or seller, 41 are Sogdian. A total of 37 transactions are listed over the course of a year comprising of brass, medicine, copper, turmeric, and raw sugar, being traded only once in that year. The more frequently traded commodities were gold, silver, silk thread, aromatics (the term xing refers broadly to spices, incense, or medicine) and ammonium chloride. (Hansen, V.; 2012) Valerie Hansen elaborates on the last commodity of ammonium chloride and states that it was used as an ingredient in dyes, to work leather, and as a flux to lower the temperature of metals. Ammonium Chloride is listed six times in these documents.
Joseph Needham summarised many of what we discovered about sal ammoniac in the 3rd volume of his monumental work, Science and Civilisation in China.
He gives context for the terms used for sal ammoniac in Chinese and its possible origin. What is of supreme interest is the fact that it was agreed on by all Chinese books that this salt came from the Western regions, including Tibet and Turfan.
He writes about the uses and origin of the salt that it “was important both medically (a stimulating expectorant or couch medicine and mild cholagogue) and chemically. Its medical use as a cough medicine continued long into the 1800’s in Europe. “Stapleton thought that it was probably introduced into chemistry by the Arabic alchemists towards the end of the 10th century, partly because they were able to prepare it by the dry distillation of hair,” a view that I still find to be widely held today. Needham continues that it nevertheless “occurs naturally in volcanic situations in Central Asia and was probably collected from there from an early date.” (Needham, J.; 1959: 654, 655)
“Stapleton suggested that the Arabic word mushadur was perhaps derived from the Chinese nao sha a suggestion which Laufer somewhat cavalierly dismissed. Laufer’s view that the borrowing was in the inverse direction was so far plausible in that no one (including Chang Hung-Chao subsequently) had been able to find any reference to nao sha in Chinese texts earlier than the 6th century AD, when the Wei Shu was written (572 AD). It had not been noticed that it occurs in Wei Po-Yang’s 2nd century AD Tshang Thung Chii where it bears a correct reference to the refrigeration effect of the salt on boils. Whether Ko Hung’s lu yen means sal ammoniac is not clear, and the next main reference in a technical book is apparently the Thang Pen Tshao of 660 AD. Now, it is indeed remarkable, as Laufer pointed out, that the orthography of the Chinese term is so fluctuating, a fact which would suggest a phonetic transcription. In works of the 7th century AD, such as the Sui Shu, variants such as noa, nung, and jao (all probably homophones of nao) are found. In the 9th century AD Mei Piao writes miu (probably also then pronounced nao). In the 6th century AD, Wei Shou (in the Wei Shu) had written kang or wang. This word persists through Thang and Sung books, and nao seems to have become definitely stabilised in the Ming.” (Needham, J.; 1959: 654, 655)
Apart from the information on the different words and a possible connection between them, we can say that the earliest reference to this salt from Chinese records is from the 2nd century AD. Contrast this with saltpeter that, in a more refined state, became common in India around the year 1300 and was found in markets with gunpowder at the beginning of mid-1500’s. In terms of what we can learn from written history, it pre-dates references to saltpeter in India by at least 1000 years.
“All the Chinese books agree (for example the Hsi Yü Thu Chi) of Phei Chü, c 610 AD; the Pên Tshao Thu of Sung Sung, c 1070 AD, and the Yeh Huo Pien of Shen Tê-Fu, c 1398) that native sal ammoniac came from the west, i.e. Szechuan, Kansu, Sinkiang, and Tibet where it was collected from the neighborhood of volcanic fumaroles.Towards the end of the 18th century, the Manchu geographer Chhi-shih-i Lao-jen said in his Hsi Yü Wên Chien Lu (Things Seen and Heard in the West Countries) concerning Kucha and Turfan: “Nao Sha is produced in the mountains of that name which are north of the city of Kucha. In spring, summer, and autumn, the caves there are full of fire. From a distance, they look like thousands of lamps, and approach is difficult because of the heat. In winter, due to the excessive cold and heavy snow, the fires die down. Local people go there to collect the sal ammoniac, entering the caves naked because of the heat.”” (Needham, J.; 1959: 655)
“In his Chu Yeh Thing Tsa Chi (Miscellaneous Records of the Bamboo Leaf Pavillion) a century earlier, Yao Yuan-Chin wrote: The mountains where sal ammoniac is produced near Kucha were called in the Thang the ‘Great Magpie Mountains’. No one dares go near them in the spring or summer. Even in the cold weather, the people take off their ordinary cloths and wear leather bags with holes through which they can see. They enter the caves to dig up (the sal ammoniac), but come out after one or two hours and could not possibly stay longer than three; even them the leather bag is scorching hot. The nao sha sparkles on the ground, but not much of it can be obtained. The product has to be kept in earthen jars with their mouths tightly closed and kept cool, otherwise it will disappear. It will also disappear if subjected to wind, wetness or damp; leaving only a white residue of granular appearance. Though this is the least valuable part, it is probably the only kind which finds its way to the central parts of China.” (Needham, J.; 1959: 655)
“These descriptions have close parallels to Arabic authors. On account of this volatility, so well recognised, ammonium chloride acquired another Chinese name chhi cha; and doubtless, because of its western origin, it was also known as ti yen barbarian salt. It was probably always impure, often mixed with sulphur and sulphites [and, may I add, nitrates]. If, as seems likely, its collection in volcanic Central Asian regions goes back very far, the earliest term may well have been Sogdian or Persian giving rise later both to mushadur and to nao sha.” (Needham, J.; 1959: 655)
The fact that sal ammoniac arrived at its destinations as “a white residue of granular appearance,” mined from the exact place that holds the largest sodium nitrate deposits and the many similarities between sal ammoniac and saltpetre; that these salts were often confused, leaves me with little doubt that even though trading records identify the salts as sal ammoniac, often, it quite possibly was salt taken from the centre of the Tarim basin containing nitrate and sold as sal ammoniac.
The mining of sal ammoniac at Turfan has been reported on in Western media as recently as 1821. An article appeared in the Gettysburg Compiler on 20 June 1821 where a Chinese encyclopedia was quoted which said that two active volcanos exist “in the interior of Tartary from which sal ammoniac is obtained by the Tartars and distributed in the way of commerce. There are cavities in these volcanos, in which greenish liquid collects, which, when exposed to the air, changes into a salt. One of these mountains is called Tourfan or the Hill of Fire and the other, Ho-Hebcon, or the town of fire. A column of smoke continually rises from the former, which, in the night becomes a flame similar to that of a flambeau. Birds and other animals illuminated by it appear of a red colour. Sabots, or wooden shoes, are worn by those who collect the salt, for leather shoes would soon be burnt.” (Gettysburg Compiler, 1821, p 4)
An interesting bit of new information is added namely that “the people of the neighborhood also collect the mother waters, which they boil in vessels, and obtain the sal ammoniac in lumps or loaves, like those of common salt.” (Gettysburg Compiler, 1821, p 4)
Sal Ammoniac and meat curing: Evidence from Modern Literature
Despite my notions about the deliberate confusion of sal ammoniac and nitrate salts, let’s ask the question if there are any modern evidence of the use of sal ammoniac in meat curing.
Here are a few references that an internet search yielded. There is the 1833 reference from Isobel Johnstone that we already referenced 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)
The 1842 edition of The Encyclopaedia Britannica reports the results of Sir John Pringle who did experiments to determine the powers of certain substances to prevent putrification in the context of meat preservation. He lists sal ammoniac as number 7 on his list with an assigned value of 3. Nitre is listed as number 9 with an assigned value of 4+. Sea salt or standard salt is listed first with a value of 1.
An 1868 publication, On Food, says that “saline substances such as saltpeter, acetate of ammonia, sulfite of potash, or soda, muriate of ammonia (sal ammoniac or ammonium chloride) etc, are also good presetvative agents” for meat. They are brushed onto the surface of the meat or injected. He makes mention of several patents pending for injection of preservatives into fresh meat by Long (1834), Horsley (1847), Murdock (1851) and others. (Letheby, H., 1870)
The very clear statement of Smith 1871/72, made from within China, in reference to how it is used in China itself serves as our strongest point of reference. Let’s repeat his statement again. “[Sal ammoniac] is said to be used in curing meat, or as a condiment.”
Hiscox lists it in 1916 along with saltpeter as a preservative in Rubrolin Sausage (spice powder). For every 100 parts by weight, take 53.5 parts by weight sal ammoniac and 42.5 parts by weight of saltpeter.
On 13 March 1989, an application is filed by Herbert F. Angermeier from Liberty Provisions Inc. from Clifton, New York, for a patent registration for a curing process for meats which comprises of ammonium chloride, ammonium phosphates, and potassium phosphates. The object of the cure is to provide a sodium free meat cure, but the fact that sal ammoniac is fascinating. (US4894249 A)
A surprising, but completely logical use of ammonium chloride emerges. I was intrigued by the timing of when sal ammoniac is added from a recipe in the Tradesman of 1809. It reports on an English method for curing ham, tongue, etc. A certain Frederick writes to the magazine offering some recipes for curing meat. He is a man with 18 years of meat curing experience who has done extensive experiments of finding cures that will last on long sea voyages and he is the owner of a commercial curing operation. He applies his recipe to pork, mutton hams, hung-beef, tongues, etc.
A cure mix is prepared with the usual amount of salt, but double the saltpeter. Salt the hams for a week and stack them on top of each other, every day, as was the custom. In the process, meat juices will be drawn from meat. For argument’s sake, take the juices thus drawn from 24 hams. Mix in the juices, 1/4 pound of fine sal ammoniac, 1 pound of Muscovado sugar. Mix it with a stick and pour it over the meat, turning it every second day for 14 days. Dry them for a week. Then smoke them using oak sawdust mixed with Juniper Berries. Smoke for another 8 days.
His total curing time is 3 week, 1-week drying and a further 1-week smoking. Total processing time of 5 weeks. The question plagued me. Why would Frederick, the astute curing artisan and business owner that he was, have added the sal ammoniac a week after the saltpeter was added when both needed bacterial action of oxidation and reduction, respectively which are both time-dependent processes.
An 1880 publication of a Farmers Guide, published by S. Anderson, Jr. from
Linwood, Delaware Co., Penn, gives the following freezing preparation. “Common sal-ammoniac well pulverized, one part, saltpetre, two parts; mix well together; then take common soda, well pulverized. To use, take equal quantities of the preparations (which must be kept separate and well covered previous to using) then put them in a freezing pot; add of water a proper quantity, and put in the article to be frozen in a proper vessel covered up, and your wants will soon be supplied. For freezing cream or wines this cannot be beaten.”
When an ionic salt dissolves in water, the reaction is endothermic meaning that heat is absorbed from the environment by the reacting chemicals. In order to compare the difference between different salts familiar to us, let’s look at the following.
1 mole of sodium chloride (normal table salt) crystals are dissolved in an excess of water, the enthalpy change of solution is found to be +3.9 kJ mol–1
1 mole of ammonium chloride (sal ammoniac) crystals are dissolved in an excess of water, the enthalpy change of solution is found to be +14.7 kJ mol–1
1 mole of ammonium nitrate crystals are dissolved in an excess of water, the enthalpy change of solution is found to be +25.4 kJ mol–1
I wondered if sal ammoniac at one point was added to meat curing to drop the meat temperature if there was a warm spell after the farmer began the process of curing? Could the later inclusion into the curing process originate from this? Tests that I did showed that this was probably not the case. In the study, I show that sal ammoniac is an excellent preservative and cures the meat in two weeks to the characteristic cured meat colour look. See The Sal Ammoniac Project.
Salt Road from Tibet to Nepal
It was the end of my first trip to Nepal. I found that clues of ancient realities are sometimes closer to the surface than we may think. I will know it when I see it. I was looking for any pointer towards or away from my hypothesis. The picture that is slowly emerging from the evidence is that nitrate salts was traded across China and used to cure meat and as a condiment.
Ayush, from Urban Food, scheduled one last meeting for us with his sales staff at their head office. Here, we had a brief, but powerful meeting with Dilip Rajbhandari.
I briefly outlined my theory to Mr. Dilip to get his input. To my surprise, he was intrigued by it and asked if I knew about the salt trade between Tibet and Nepal. Of course, I did not and he explained it to me. More than that, he encouraged me to go to an old market in Kathmandu where I would meet salt traders from Tibet.
This small tidbit of information is the kind of pointer I was looking for. Normal, unforced common knowledge facts which point to either the confirmation or contradiction of my theory. This one seemed to confirm my suspicion.
Fisher states it very simply that in Tibet, grain was more valuable than salt since they have rich salt deposits, but lacks grain. In Western Nepal, they have an abundance of grain and no salt. (Fisher, J. F; 1978)
Stong ties existed since antiquity between Nepal, India, China and the kingdoms surrounding Turpan and Turpan itself. There was a free flow of scholars (for the large part) and trade in various salts, including and chiefly sal ammoniac.
That night we visited the ancient markets of Kathmandu and we tasted and talked about salt until late into the night.
I found more evidence of the trade in sal ammoniac than in the trade with saltpeter early on in the Christian era. It is safe to assume that this was the case for hundreds, if not thousands of years before written records started keeping record of and describing these.
Technically sal ammonia fits the profile as a good meat curing agent and good documentary evidence support the notion that it was used as such before saltpeter became more widely available by industrial demands.
It seems unlikely that meat curing started in India and it leaves the Turpan area as still the candidate for this designation with the best credentials.
It is likely that sal ammoniac miners and traders substituted the crystals which they mined from the volcanic mountain in the Turfan area with salt from the basin itself which contained nitrates in the form of sodium nitrate which makes for very poor gunpowder on account of the sodiums high affinity for moisture, but a very good curing agent for meat.
Sal ammonian from Turfan and Tibet probably made its way into Nepal, the eastern and western regions of China and through Samarkand, into the Mediterranean. Sal Ammoniac was produced in the region of Samarkand also, but the question is if they produced enough since almost everything they produced were exported indicating a strong demand and limited local supply which, I assume, was supplemented with stock from Turfan and Tibet.
The hypothesis that meat curing originates from the Turfan area is undoubtedly supported by this evidence. The fascinating journey continues!
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