The distillation of alcohol


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You might have noticed that my blog posts are sometimes spurred by perceived errors or mis-statements in other peoples works. I think it important that criticism is made and better information disseminated, and since I don’t own a newspaper or TV station, I have to make do with this blog. Also it often helps refine my own thought and provides a spur to reseach. I have often changed my mind/ position on something after re-reading and researching the subject. I also find that I understand and think about things better when contrasting them with other ideas rather than in a vacuum.

Today’s example is in Rasmussen, “Advances in 13th century glass manufacturing and their effect on chemical progress”, Bulletin of Hist Chem, vol. 33 number 1, 2008. Which can be found here.

It summarises various bits of research suggesting that Venetian glass makers in the 13th century improved their recipes by the use of Levantine plant ash. The use of these soda and quartz glasses, low in P and Fe and with increased lime and magnesium, would, he says, have given improved capabilities to withstand chemical attack. This part of the paper is clear enough, and I have no great quibble with it, although I have not read the papers he references to back up the physical properties of glass with such Mg and CaO contents.
The weakest thing is that he quotes only 4 different analyses of glass from Venice, which is hardly a representative sample. They are from the 9-10th century and 11-14th centuries, and so whilst they do show a difference in composition, I am still rather wary. It has happened before that someone has promulgated something that is correct with the backing of insufficient evidence, or made statements which suggest a greater accuracy and precision in dating than is acceptable from the evidence adduced. A lot of what he uses is circumstantial, such as dates and changes in practise and use which are not well understood. So this paper is perhaps better understood as offering a theory with further work required to re-inforce it. Or so I think.
Continue reading

The use of stone moulds in 13th century Germany


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A few weeks ago I found a couple of papers by Daniel Berger, a german researcher who has studied a large group of 13th century stone moulds used to cast pewter objects. Unfortunately they were in German, but I could get an idea of what they said. The photographs too were very useful, and showed stone moulds of extraordinary complexity, much more so than any known so far in Britain.
Fortunately he’s put much of his work online, including his PhD thesis:
Click here to see the list.

Anyone interested in pewter badges and related objects should read them, or at least copy and paste into google scholar to get an idea of what he is writing about.

Dyeing wool yellow with weld


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Weld, a tall woody stemmed plant, was used in medieval times to produce a yellow colour, or after a second dyeing with woad, green. I’ll get round to woad later, but in the meantime, here’s what I did.
I followed the simple instructions given in The medieval Dye pot” by Dee Duke, no. 3 of Woolgathering for dyers and Spinsters. Frankly, I didn’t bother weighing anything because I couldn’t be bothered and figured it would be fun to be a bit random about it. What I did do was alum mordant the wool and let it mature for 3 days beforehand.

There were two attempts, first, I boiled some weld with a caustic solution made from lime, for around 45 minutes. The instructions say to let it cool and strain off the dye, and it should be cold before you put the wool in and start heating.
Here’s the solution at that sort of time:
weld bits in yellow water Continue reading

The use of original artefacts by re-enactors



Is something I mostly object to, especially when they are more than one or two hundred years old. I’ve actually seen a couple of people offering medieval buckles for sale attached to leather belts.

There are two reasons why I think this is wrong. One is that you are wearing out a historic artefact by using it; we have a limited number of them, and I’m sure that future wars, accidents and fires will decrease the stock well enough without you helping.
Secondly, in some cases such as belt buckles, you simply can’t get the same look as with the original, because surprise surprise, there’s 600 years patina of corrosion and you can’t polish it back up to how shiny and smooth it would have been when new. They wouldn’t have worn a dark surfaced slightly pockmarked buckle, so neither should you. Your clothing and accessories should be aimed at producing a medieval (or other, insert to suit) impression, not one of someone dressing up medievally or what they think people looked like in films.

If thinking about gold or silver, see point one. Buckles and the like count as both one and two. There might be some objects which manage to be in good condition and not wear out, but they are few and far between.
Other periods like WW2 I’m a bit less bothered about, but are you sure there are copies of your uniform/ book/ folding stool in storage somewhere for the future, before you wear them out with use?

Something many people don’t know about high medieval times


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One thing is that people didn’t have what we think of as cups or mugs. They used wooden bowls instead, and plenty survive in the archaeological record. If ordinary people used cups we would expect to have some evidence for them, but no, there aren’t any, nor are there pottery ones until well into the 14th century.

Often called mazers, such bowls are seen in plenty of artwork, and one precious one survives from 1320′s Scotland! The Bute mazer:

which is a communal drinking bowl larger than mine.

More information on mazers and drinking bowls can be found here:

I got a lovely set of bowls and spoon, hand made using a pole lathe, from Paul Atkin, a nice helpful fellow down in England, whose website is:

if you want some yourself, but hurry, he’s selling out fast and won’t be able to make more until later in the year.

Here they are:
new wooden bowls

The one on the left with the thinner rim can be drunk from. I might thin the rim down a bit more, but it works well enough with your mouth inside or outside the rim.
The reason for getting them is upgrading my kit, since I know so much more about the material culture of the early 14th century than I used to, I shall stop using my pottery drinking vessel, a pottle, and use the bowl instead.

Apart from bowls, the Perth High street excavations undearthed a number of staves which came from tankard like pots and would have been the right size to use by yourself, so I think I am justified in suggesting that they would have held ale or water. I would get such a vessel, but manufacturers are hard to find and storing them so they stay useable and watertight is hard to do.

I wonder how many people I can persuade this season to change to drinking bowls rather than any form of mug or cup, when visiting 1305 or 1314?

The value of a scholarly edition and/ or translation of a work is far beyond the text itself


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I have noticed this before, but it bears repeating – that scholarly editions are much more than their text. I’ve often found the introductions and notes at the back much more useful than the text itself, the reason being that they show the context and explain words and concepts which are usually very unclear in the text itself. Of course some of the explication might be wrong, but it is usually at least a good starting point for further explorations. The notes often bring to light things which earlier translators simply didn’t know, but now thanks to decades more work things are better known.

For instance, in the current hot off the presses book, “The four books of Pseudo-Democritus” by Matteo Martelli, published by the Society for the History of Alchemy and Chemistry, as part of their Sources of Alchemy and Chemistry series, we find a number of explanations on substances and their uses in the 4 books which have not, as far as I am aware, been made so clearly and in such depth before, at least in English.

On page S221, we find discussion of the word kadmia, which from Pliny means both zinc ores and the substances scraped from chimneys of furnaces in which such ores have been roasted. On the next page is the next note which discusses the use of such kadmia, and its dissolution in various yellow liquids, including calfs bile, and other oils. The texts referred to include the Papyrus of Ledyen and Holmiensis, as well as some of the Syriac alchemical manuscripts and a work by Zosimos.
The next note discusses the term Androdamas which is probably a form of iron pyrite with cubic crystals, and Martelli mentions a number of texts and sources of information, and ties the term in with the actual recipe.

If however you rely on the older English translation by Steele, you would think that Androdamas is a form of arsenical pyrites. He gives no source for this. The waters are further muddied by Martelli mentioning that the “Lexicon on the making of gold” “idnetifies androdamas with pyurite and orpiment”. It can’t be both iron pyrites and orpiment, or rather two different people might have had different names for it 2,000 years ago, so now we have a more complex and complete understanding of the word as used in the period, which simply was’t available back in the 1920′s, or at least not unless you’d carried out several years of research of your own. But now modern researchers can build on this work and the translations and concepts contained within it.

The Steele translation can be found at Adam Macleans website:

There are noticeable differences between it and the Martelli translation.
For instance, recipe one of Steele says:

“Taking mercury, thrust it into the body[3] of magnesia, or into the body of Italian antimony, or of unfired sulphur, or of silver spume, or of quick lime, or to alum from Melos, or to arsenic, or as thou knowest, and throw in white earth of Venus,[4] and thou shalt have clear Venus; then throw in yellow Luna, and thou shalt have gold, and it will be chrysocoral reduced into a body.”

But Martelli says:
“Take Mercury and make it solid with the body of magnesia, or with the body of Italian stibnite, or with unburnt sulphur, or with moon foam, or with roasted lime, or with alum from Milos, or with orpiment or according to your knowledge. If it (i.e. mercury) turns white, lay it on copper, and you will have shadowless copper, (if the mercury turns) yellow, lay it on silver and you will have gold, on gold and it will be solid gold coral.”

Some of those differences are quite important, and ultimately the Steele version feels odd, whereas the Martelli one fits the language and form of the other translations of similar recipes from the same era.
The reason for this is of course the fact that Steele translated from a 16th century Latin translation of the original Greek, whereas Martelli has used the oldest surviving Greek copies, compared them to the Syriac and collated together a text that is much more accurate than the Latin one or the English translation thereof.
And the notes have a most interesting discussion of the substance ‘moon foam’, which Steele thinks is argentiferous litharge, but according to the discussion is nothing of the sort.

There are more translations to come, I’ll just have to bear the wait. They are being made possible by the generosity of Robert Temple who has sponsored this and other volumes to come.

Contamination of saltpetre in medieval and post-medieval Europe


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Who cares about contamination of saltpetre?
Alchemists and people whose lives depend on making things go bang, that’s who.

Regarding the alchemists, Lawrence Principe (on page 65 of his “The secrets of Alchemy”) brings to our attention a work by John of Rupescissa (or rather of Roquitaillade as he is knowin in France, which was his birthplace) that tells us how to purify saltpetre of salt. The De Confectione attributed to him has a section near the end on the use of fractional crystallisation to produce pure saltpetre. However the same text also has an added section which describes the importance of table salt and states that “The whole secret is in the salt”.

This is in the context of an important recipe at the start of the text being the distillation of a mixture of roman vitriol, saltpetre and mercury, producing a substance that is white like snow. To make this, presumably mercuric chloride, requires the element chlorine to be present with the mercury. But what confuses me is why would you give a recipe for removing the salt, then suggest obliquely in the next paragraph that you had to add the salt in again? Continue reading


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