Textiles, storax and the alchemy of alum

I like this post – I think it’s a nice mixture of deadly-boring, fairly useful, and just a tad exciting.

 *Jan 13th – I’ve now moved the most boring part to the end of the post*.

Post includes:

Terms for weights and measures used in the 12thC trade between Alexandria and India (compare with the same use of the ratl or rotl in fourteenth century Mediterranean e.g. the Zibaldone da Canal.

Fol.6v (botanical folio) identified in passing as  including Liquidamber orientalis in this group. L. orientalis being the source for storax (technically not to be confused with styrax, though the confusion occurs in ancient, medieval and even modern internet sources).

Post ends with a long précis-of-an-extract from a monograph on Alum – (this re Genoa and Venice and routes).


Weights and Measures of the India trade (c.12thC)

Goitein’s papers on the medieval trade with India include terms used for weights and measures. Original documents are reproduced in the papers, showing how fractions were being written in the 10th-12thC AD:  in Arabic, Judeo-Arabic and Hebrew.

Details are given about the exact proportions of one good or another (by volume/weight)  set aside as tax or duty. The Jewish traders used the same term for customs duties and tax as for religious tithing though secular imposts varied with the time and goods.

One of the reasons I include this arithmetical part is that a friend of Kircher’s commented in reference to the manuscript that  it was a pity there was “so little interest in mathematics” during their own time.

I must say that as I read through Goitein’s lists of goods, a number are familiar from work previously done on this manuscript, some of which has already been posted on this, or on other sites.  There are also included some about which I haven’t posted yet.  And in case you suspect that my results are tailored to suit a thesis based on Goitein’s documents – no,  I don’t work that way, and I think that the manuscript had taken its settled form long before the twelfth century.

I’ll quote from just two articles:

Goitein, S.D., ‘Portrait of a medieval trader: three letters from the Cairo Geniza’, Bulletin of the School of Oriental and African Studies, Vol.50, No.3 (1987) pp. 449-464.

Goitein, S.D., ‘From Aden to India: specimens of the correspondence of India traders of the twelfth century’, Journal of the Economic and Social History of the Orient, Vol.23, No 1/2 (April 1980) pp.43-66.

Corals and storax are mentioned as luxury goods, traded via Alexandria and Aydhab to India.   The plant-group on f.6v includes storax (Liquidamber orientalis), I should think.

other goods:

Mats, (cf. unguis – f.1v)

sappan wood (I have identified this in the manuscript, but not yet published the paper)

fine aloes wood ‘brnh‘ from Persian? agar bih; (agar wood – f.16v  – published last year)




betel nuts,

an Abyssinian hide (slave?);

fringing? (lit: ‘chain collar’)

The pair of terms could refer to either, but a band of chain-stitched ornament on a treated hide meant as a floor- or wall-cover would not be unusual.

There is also mention of a fine carpet ornamented with a zodiac (Ar: burüj)

One list of goods:

… a Mediterranean merchant sojourning in India.. He exported iron, a commodity not handled by Jews in the Mediterranean but [which took] pride of place in the India trade; spices, such as pepper and ginger, and betel nuts, and of course, the products of his brass factory. ..the West sent gold coins of various currencies and those daily commodities which Westerners out in India needed or desired: Spanish and Egyptian textiles, writing paper not be had in India at all [the last statement is a little contentious – D.], sugar, raisins and dates and household goods.

Weights and Measures.

(I’ve bolded integers for clarity).

Pepper – 12 bahār [= 100 rotl], from which 45 rotl were removed [as tax/impost], leaving 11 bahār, 255 rotl.container VM 99rii

The price: per bahār – 34 dinars, per rotl – 34/300 dinar.

Total: 374 dinars + (24 x 255/300) = 28 9/10, rounded out to 28 5/6 = 402 5/6 dinars (Malik.)

Expenditures on this shipment:

Tithes (i.e. customs) 82 1/4 dinars

Comment (DoD) Some list of imposts or taxes, as origin for the ‘pharma’ section could explain the red cylinders’ pairings. Other possibilities include a distillation process, or the larger’s representing raw materials while the smaller referred to the end- product.

I’d be inclined to think the ‘pharma’ section did begin as a tax list, but for taxes paid to agents of  Parthia, India or – later – Chinese and Mongols.

Another typical order in arithmetical calculations. This Goitein’s translation – he reproduces the originals.

Expenses in receiving the goods 4 1/6 dinars

Baskets and porters  87 5/6 dinars    87 5/6

Balance in favour of Ben Yijū from the pepper shipment  315 dinars.

On measures and their vocab. see note 21 (p.99) in same article.

Tithes (i.e. customs) 82 1/4 dinars.


I like the way this is starting (hmnn – well yes..) starting to fit together. Not too specifically, but generically.



Singer’s monograph.

Charles Singer, (1940), The Earliest Chemical Industry: An Essay in the Historical Relations of Economics and Technology Illustrated from the Alum Trade.

(According to Google, copies are still available from the Folio Society;

Intro – mine.

Alum’s importance in textiles and dyeing is due to its role as a softening agent for fabric,  ivory and leather, allowing the dye to work more effectively and leave the material soft as well as more deeply coloured.  The Mappae Clavicula refers to alum, trade in which was so intrinsic to these activities, as to painters and others, that the alum trade has to be considered against any posited relation between the Vms and a given profession or trade, especially one involving pigments or textiles.

Before the fifteenth century, Europe was largely dependent on natural occurrences of alum and first Genoa, then Venice dominated the trade.

As one of the most widely-used mordants in the ancient and medieval world,  alum was the mordant preferred for  silk. Its natural occurrences are usually in small quantity, but a form from which alum can be produced is associated with local volcanic activity (yes, I know – atacamite..)

As example of ‘local volcanic activity’ producing alum crystals. Here’s the picture of a cave in Romania. Puturosu mountain, This cave is known as  Timsós which I was intrigued to find means in Romanian either alum- or bear-.

After the long passage below, summarising Singer on Alum, the more mercantile and botanical bits follow.

The ‘quotes’ below merely  precis a summary of Singer’s monograph that you can see in full at Whatmans and Wove site.

Alum was used mainly for mordanting; for tanning and softening leather; for its alleged medicinal and cosmetic properties; and as an auxiliary agent in miscellaneous metal and glass finishes.

The earliest known uses of alum in the Mediterranean area, and indeed anywhere, are referenced in records from dynastic Egypt (in c. 2000 B.C.) …Alum’s use can be deduced from the type of thing for which it was used, both local applications and those found in other countries, e.g. descriptions in cuneiform on Mesopotamian tablets of the 8th C. B.C.

By the 5th C. B.C. significant quantities of alum were being exported from Egypt to other countries in the Middle East.

The extension of the alum industry from Egypt to other regions is an extremely complicated subject, partly due to the linguistic problems it raises, ensuring that one is concerned with alum and not with another substance; and, more important, the confusing effects on trade of one empire after another being superseded in Asia Minor and Eastern Europe, from Persia in the east, through North Africa to Spain in the west, continuing from early periods right up to the Middle Ages. The Greek, Roman, Byzantine and Arabian civilizations were all involved, together with other sources of influence, penetrating this world from India and, by the silk route, from China. For detailed information on the effect they had on the supply and use of alum see  Singer’s monograph.

The first methodical statements on the nature of alum [that are extant] are set out in Arabian  alchemical documents of the 8th-10th C. (A.D.), a time when trade links [with Europe]  were strong.

Demand for alum was ancient, but from the 10th-12th centuries AD as  dye-works, and consequent use of alum, had become increasingly the work of those Jewish communities who had earlier migrated from the Byzantine empire to Italy and Provence, and from Tunis into Spain. Another of the important centres for dyeing at that time was in Alexandria, convenient to the Kharga oasis where small quantities of natural alum crystal occurs (K2SO4.Al2 (SO4)3.24H2O).  From here the alum was  gathered by the Bedouin and shipped down the Nile to Alexandria.

rock Alum Arabia

Alum from Arabia. Said to be ‘rock alum’

The Yemen was another natural source, though in this case only available as crude aluminium sulphate whose conversion to ammonium alum required skill. Urine was first added, then the solution was boiled and the alum allowed to crystallize out as the mixture cooled.

Other than these two natural types,  alum comes from two other principal sources, alunite (alum rock or alum stone) and alum shale (alum ore or alum schist).

geog alum ammonia crystallised out

Ammonia alum crystallised out – India

Some European countries favoured supplies brought from Sicily and the Aeolian islands; Spain had its own resources, with especially high quality alum coming from Castile; but the best still came from the Middle East.

During the 12th C. AD, many of the established trade routes were interrupted by crusades, aggravating conflicts between Saladin and the declining Byzantine Empire, and the last of them helped the final polarization between Roman and Eastern churches.

To add to these difficulties, Baghdad was sacked by the Mongols in 1258, even as the Turks were beginning to dominate the middle east.

During this time, Genoa had been building lasting trade links with north-western Europe, e.g. with important centres such as the Duchy of Burgundy and the extensive markets of the Hanseatic League in the Baltic. It also acted as a middleman in the textiles trade, dyeing and finishing textiles imported from those centres and selling them to Sicily, Egypt and the Levant.

Genoa’s alum came through Alexandria and through Bejaïa (Algeria), rought by caravan from Lake Chad. Other souces were in Castile and Greece. Genoa was also to this trade from the Black Sea and eastern coast of Asia Minor, although centres in Asia Minor were  especially vulnerable to embargoes or attack from the Turks.

As Byzantium declined, and with its ultimate fall, the ascendancy of Venice began and would overtake Genoa in the alum and textiles trade routes. Venice had been a subject of the Eastern Empire since the ninth century, and had steadily acquired important concessions in almost all parts of the Levant. It had strong settlements in Constantinople, Cyprus and Crete, giving it access to numerous sources of alum and although Venice had initially served simply as a carrier of goods including alum to other parts of Europe, it now had growing industries which themselves needed the substance. With Constantinople’s fall in 1453, and Turkish control established over the Levant, western Europe needed to develop its own supplies.

Deposits of alunite (K2SO4.Al2(SO4)3.2Al2(OH)6) occur  in Asia Minor, and all over Italy, as for example, near recent volcanic activity (Piombino, Volterra, Pozzuoli near Naples, Elba and the Aeolian islands).

Large quantities of trachyte are found in this environment (igneous rock formations composed mainly of aluminium silicates), and these had been converted by local volcanic discharges of sulfurous fumes or acid into alunite – half-way to alum. To complete that process, it was necessary to alumina from the alunine by roasting and lixiviating the ore, extracting the alum, which was then purified further by boiling and re-crystallization.

Only areas of active or extinct volcanic extrusion provided alunite, and still other means to obtain it were needed for the growing demand.

Alum shales (so-called) would provide the answer, but although Singer mentions al-Razi’s laboratory extraction of alum from shale in the 13thC, there is no evidence of the method’s industrial application before the fifteenth century.

At some time early in that century, and apparently accidentally, the method was first exploited in the Tyrol. An alum works was then established not far from Innsbruck, attracting the attention of prospectors from Venice, Verona and Saxony. News spread quickly to other parts of central Europe, notably Bohemia, Silesia and adjoining districts, where by the mid-16th C. many alum works had been set up.



2 thoughts on “Textiles, storax and the alchemy of alum

  1. I’ve had a couple of queries about this post since I wrote the summary of the Aegean issue and posts.
    I should have been clear that the Aegean came up during the research – only a fraction of which is ever included in these posts – whose length still brings complaints. 🙂

    Discussions online – efforts to tell people about this and other items found such as the fat-tailed sheep and a certain vegetable substance also gained from Chios .. then led to Bdid1dr looking at the island’s history, topography and industries in some depth. Unfortunately, she never maintained a website or blog, so finding details isn’t easy. Deserves the credit, nonetheless.

    I guess the reference most likely to prove useful to the linguists and cryptographers – as whose reference-stock all these posts were intended* –
    Christopher Wright, The Gattilusio Lordships and the Aegean World 1355-1462. (2014) Sorry, it is another Brill, but if you can get hold of it… See esp. Appendix 3.


    * – which of course doesn’t obviate the need to cite the present researcher – just to keep everything straight, clean, and useful to others. Pity to have to say so, but there you go.


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