image database: CuAs-alloys

Following the links below, you can find images of cross-sections of different Cu-As alloys. In the upper right corner, you have the indication for the percentage of Arsenic, followed by the indication of annealing time (in min.), the amount of deformation (in %), and the magnification (the bars with the indication of size are in a separate image). Just ignore ‘quer’ or ‘copy’ in the filename. The samples were first deformed (and yes, it is possible to deform CuAs-alloys up to 98% without cracking!), and then annealed. All samples are cross-sections.

To give you an example: Image ‘1As_20min_40def_quer_100x_3 copy’ means that a sample of CuAs-alloy with 1 wt.% As was 40% deformed and afterwards annealed for 20min. The magnification is 100x.

Here is the overview of samples and treatment:

  • Chemical composition: 1, 2, 3, 4, 5, 10 wt.% As
  • deformation (cold rolling): 0, 20, 40, 60, 80, 98%
  • annealing time: 0, 20, 40, 80 min at 600°C in reduced atmosphere
  • After annealing, the samples were quenched in water.

Images (follow the links):

…be patient with the scratches: The alloys arereally soft after annealing and it wasn’t a pleasant experience to polish these samples!

It’s spring again and there are still a lot of pigeons in Vienna…

An alternative usage of arsenic as described by Georg Kreisler  (information in English) in his black humour chanson ‘Tauben vergiften‘ [poisoning pigeons] due to the high number of pigeons in Vienna in the 1950ies.

Tauben vergiften

Schatz, das Wetter ist wunderschön
Da leid ich’s net länger zu Haus
Heute muss man ins Grüne gehn
In den bunten Frühling hinaus!
Jeder Bursch und sein Mäderl
Mit einem Fresspaketerl
Sitzen heute im grünen Klee –
Schatz, ich hab’ eine Idee:Schau, die Sonne ist warm und die Lüfte sind lau
Gehn wir Tauben vergiften im Park!
Die Bäume sind grün und der Himmel ist blau
Gehn wir Tauben vergiften im Park!
Wir sitzen zusamm’ in der Laube
Und ein jeder vergiftet a Taube
Der Frühling, der dringt bis ins innerste Mark
Beim Tauben vergiften im Park

Schatz, geh, bring das Arsen gschwind her

Das tut sich am besten bewährn
Streu’s auf a Grahambrot kreuz über quer
Nimm’s Scherzel, das fressen’s so gern
Erst verjag’mer die Spatzen
Denn die tun’am alles verpatzen
So a Spatz ist zu gschwind, der frisst’s Gift auf im Nu
Und das arme Tauberl schaut zu

Ja, der Frühling, der Frühling, der Frühling ist hier
Gehn wir Tauben vergiften im Park!
Kann’s geben im Leben ein größres Plaisir
Als das Tauben vergiften im Park?
Der Hansl geht gern mit der Mali
Denn die Mali, die zahlt’s Zyankali
Die Herzen sind schwach und die Liebe ist stark
Beim Tauben vergiften im Park…
Nimm für uns was zu naschen –
In der anderen Taschen!
Gehn wir Tauben vergiften im Park!

GMPCA conference, Rennes – Poster

AccueilDuring the last days, I have been at the 21st international GMPCA conference in Rennes, France, listening to a lot of very interesting papers. The conference is THE conference for ‘archaeometrists’ in France and a fantastic opportunity to meet colleagues and researchers of all fields of archaeometry. Together with Benjamin Sabatini I presented a poster on Chemical and metallurgical aspects of arsenical bronze: inverse segregation in prehistoric Cu-As objects. You can find the poster for download here.

Getting used to arsenic

A recent publication in the American Journal of Physical Anthropology describes how humans adapted to arsenic in Andean populations of the Atacama Desert. It is here, where the highest arsenic levels in the Americas are found (>1,000 µg/L). The local population though, the Camarones people, who live in this environment during the last 7,ooo years, have not presented any epidemiological emergencies.

So the authors of the study – Mario Apata, Bernado Arriaza, Elena Llop and Mauricio Moraga fom the Universidad de Chile in Santiago and the Universidad de Tarapacá – compared the frequencies of four protective genetic variants of the AS3MT gene associated with efficient arsenic metabolization, between the living populations of Camarones and two other populations historically exposed to lower levels of arsenic. They found higher frequencies of the protective variants in those people from Camarones than in the other two populations.

The higher frequency of protective variants in both northern Chilean populations indicates a long exposure to naturally arsenic-contaminated water sources. The data suggest that a high arsenic metabolization capacity has been selected as an adaptive mechanism in these populations in order to survive in an arsenic-laden environment.

However, one has to note that a third of the population does not have any of the protective genetic variants of the AS3MT gene and still does not show any significant signs of arsenicosis – further research is planned (or maybe they should visit Styria?).

(for further info, see the article here).

Colour measurements of copper alloys

CIELAB coordinates (SCI) with error bars (standard deviation: 2σ) of different arsenical bronze alloys.

CIELAB coordinates (SCI) with error bars (standard deviation: 2σ) of different arsenical bronze alloys.

The color characteristics of different copper alloys of particular interest in archaeometry (Cu-As, Cu-Sn, Cu-Sb, Cu-Ni) are investigated quantitatively and systematically. By using the CIELAB color system, different color parameters such as a*, b*, and L* were measured by a spectrophotometer in order to describe the surface color. This permits the establishment of a set of color-composition diagrams, demonstrating clearly the connection between chromaticity parameters and alloy composition.

With the evaluated data it is possible to start thinking about the role of color in technological choice, because it allows us to estimate the color of prehistoric metal artefacts with comparable compositions. A better understanding of the association between metallurgical alloy and color will aid the research of prehistoric metalwork because choices in production and use of metal were likely influenced by the particular qualities the material had to offer, of which color is an important one.

The article, which has as co-authors Daniel Berger and Maikel Kuijpers, was submitted recently and will be hopefully published soon. I keep you updated!

Late Bronze Age Caucasian daggers made of arsenical bronze… and tin bronze

Several Late Bronze Age Caucasian daggers were studied in order to evaluate their chemical composition and microstructure. The daggers derive from North Ossetia-Alana, Russia, and are since the 1880ies in the Natural History Museum Vienna. The arsenical bronzes are characterised by a high amount of arsenic (2-5wt.%), as are the tin bronzes by high amounts of tin in the alloy (10-17 wt.%). However, most of the dagger blades studied are ternary Cu-As-Sn alloys. Two arsenical bronze blades show intense segregation of γ-phase along the blades’ surface and the grain boundaries (remember my article on inverse segregation of arsenical bronzes!); some of the arsenical bronze blades also show eutectic, which hardness could be measured. One dagger was made of a tin-bronze blade and an arsenical bronze hilt (see Figure on the bottom). The article will include chemical analyses, metallographic studies, hardness measurements, and Pb-isotope analyses. I’ll keep you updated once it’s published!

Late Bronze Age dagger from Koban, Republic of North Ossetia-Alania, Russia. The colour of the hilt was silverish while the blade had a warm, golden-like colour. The hilt contains about 9.8 wt.% arsenic and no tin, while the blade contains 10.1 wt.% tin, and no arsenic. Today, the dagger is very much corroded, so the original colours of the metals are not any more visible (Photograph © Naturhistorisches Museum Wien; inv.no. 41.268).

Late Bronze Age dagger from Koban, Republic of North Ossetia-Alania, Russia. The colour of the hilt was silverish while the blade had a warm, golden-like colour. The hilt contains about 9.8 wt.% arsenic and no tin, while the blade contains 10.1 wt.% tin, and no arsenic. Today, the dagger is very much corroded, so the original colours of the metals are not any more visible (Photograph: M. Mödlinger, © Naturhistorisches Museum Wien; inv.no. 41.268).

Hardness measurements of different Cu-As phases

Caucasian dagger blade made of arsenical bronze with 4.5 wt.% As; the hardness of the eutectic could be detected.

Caucasian dagger blade made of arsenical bronze with 4.5 wt.% As; the hardness of the eutectic could be detected.

Finally, all samples are polished, so I can start with hardness measurements. Here, I would like to thank especially Fabrizio Barberis, DICCA,  and Armanda Barbangelo, DIME, both Università degli Studi di Genova, for the possibility to carry out all hardness measurements with them. In that way, I was able to use both a purely mechanic, historic instrument, and could carry out also μHV measurements on my arsenical bronze alloys, as well as on Late Bronze Age daggers from Koban. The publication of the analyses of the daggers is currently in preparation, and will include chemical analyses, metallographic studies, hardness measurements, and Pb-isotope analyses.

Polishing, polishing, …

Polishing a few alloy samples

Polishing of a few alloy samples (selection)

After annealing and deformation of a lot of samples, I am busy with polishing. Polishing of a lot of samples. Also, the next article on ‘Arsenical bronze: a constant out-of-equilibrium’ is almost ready for submission. Further articles on the loss of arsenic during recycling activities, and on the colour of arsenical bronze, are in preparation.

100 years ago, arsenic was everywhere

I would like to share an article by Haniya Rae from The Atlantic here with you, which was published this October. You can find the following article here, referring to the new book ‘Bitten by Witch Fever‘ by Lucinda Hawksley.

Slightly over a century ago, poison was a common part of everyday life. Arsenic, the notorious metalloid, was used in all sorts of products, primarily in the inks and aniline dyes of beautifully printed wallpapers and clothing. Odorless and colorless, it went into food as food coloring, and it was used in beauty products, such as arsenic complexion wafers that promised women pure white skin, until as late as the 1920s. It was found in the fabric of baby carriages, plant fertilizers, medicines. It even was taken as a libido pill in Austria.

The literature of the era hints at the effects from arsenic poisoning. The main character in Charlotte Perkins Gilman’s 1892 short story “The Yellow Wallpaper,” for instance, descends into madness and believes that the source of her illness stems from the wallpaper in her room. “It makes me think of all the yellow things I ever saw—not beautiful ones like buttercups, but old foul, bad yellow things,” she says. “But there is something else about that paper—the smell!”There are numerous studies on William Morris’s arsenic-laden wallpapers, in particular, which were extremely popular during the late 19th century. Morris himself, a designer and artist, was also the heir to the world’s largest copper mine at the time, which produced arsenic dust due to mining activity. Not only did the mine cause massive environmental damage to the land around it, but many miners died of lung disease, according to a 2003 article in Nature. Morris’s famous phrase about the doctors who treated these miners was that they “were bitten by witch fever,” insinuating that the doctors were quacks when they diagnosed arsenic poisonings. He was unwilling to believe the catastrophe his businesses had caused.

Using Morris’s phrase as a fitting title, the art historian and Victorianist Lucinda Hawksley’s new book, Bitten by Witch Fever, tells the story of the extensive use of arsenic in the 19th century. It includes pictures of objects and artworks made from substances that incorporated arsenic, and advertisements for arsenic-filled products for Victorian women, such as soap with a doctor’s certificate to ensure its harmlessness.I spoke to Hawksley about arsenic’s prevalence in 19th-century home decoration, clothing, food, and topsoil. Our conversation has been condensed and edited for clarity.

Haniya Rae: Why was arsenic so commonly used?Lucinda Hawksley: In mid-Victorian times, Pre-Raphaelite and Aesthetic artists were particularly sold on this vivid shade of green, found by the Swedish chemist Carl Wilhelm Scheele in the 18th century. The green color came from copper arsenite, known as Scheele’s Green, which is a form of arsenic and a byproduct of the copper industry.If you think about the brilliance of copper and the way that a patina begins to color metal, it’s a beautiful color. Chemists hadn’t thought about how poisonous arsenic was, which today would seem crazy to us—it was present in so many things. Victorians didn’t think it was a problem unless you ate it. They hadn’t made the connection that the same thing that created this amazing green, and that was immensely fashionable in the 1860s and 1870s, could be a problem. It wasn’t just the Victorians, though—Germany, the United States, Scandinavia, among others, were all using arsenic in common goods.

Rae: By the late Victorian period, though, people had started to figure out it was dangerous?Hawksley: Around the 1860s, the cases of arsenic poisoning started getting to the newspapers. One wallpaper manufacturer debuted arsenic-free wallpaper, but no one paid much attention to that, until more and more cases started appearing. By the 1870s, William Morris started to produce arsenic-free wallpapers. At this point, William Morris himself didn’t actually believe that the arsenic was the problem—he was simply bowing to public pressure. He thought because no one was ill in his house from the arsenic wallpaper, it must be something else that was causing the sickness.

 Rae: What were a few of these cases?Hawksley: Factory workers were getting sick—and many died—because they were working with green arsenic dye. It was fashionable to wear these artificial green wreaths of plants and flowers in your hair that were dyed with arsenic. In wallpaper factories, workers were becoming really unwell, especially when they were working with flock papers, or papers with small fiber particles that stick to the surface. The workers would dye these tiny, tiny pieces of wool or cotton in green, and while doing so would inhale them and the particles would stick to their lungs. The manufacturing process created a lot of dust from the dye—the dust had arsenic in it—and this created major problems for the factory workers as the dust would stick to their eyes and skin. If there were abrasions on their skin, the arsenic could get directly into their blood stream and poison them that way as well.
When the newspapers started to point out that this was happening, most people didn’t care. It’s a bit like today. People will still buy a brand of chocolate even if there’s been a story on how the chocolate has been produced by slave labor. They buy coffee that was also produced by slaves. They buy clothes, even though it was made by bonded labor. As long as people get what they want, most people don’t think twice about it. If they were confronted with things face on, of course they wouldn’t buy these products.
 Rae: Did Britain ever pass legislation about arsenic?

Hawksley: In 1903 century, the U.K. actually did pass legislation about the safe levels of arsenic levels in food and drink—even though often there are no safe levels at all—but Britain never passed laws around wallpaper or paint. By the time the regulations were passed on arsenic in food and drink, arsenic wallpaper and paint had fallen out of fashion, so it’s possible they didn’t see a reason to actually pass legislation against it. To this day, there still isn’t a law banning someone from making arsenic wallpaper or dye in Britain.Rae: But it was pretty bad before that point?Hawksley: Before legislation was passed, bakers used arsenic green as a popular food coloring. Sometimes, a baker was given flour or sugar with arsenic in it unknowingly, but other times it was used as a bulking agent. You wouldn’t believe the kinds of things that were put into Victorian foods as bulking agents. It wasn’t just arsenic, there were lots of weird things. Flour was expensive, so they would resort to adding other things.There was an orphanage in Boston and all these small children were getting really, really sick and they didn’t know why. It turned out that the nurses were wearing blue uniforms dyed with arsenic and they were cradling the children, who in turn were inhaling the dye particles.That’s another thing, too: Green was a color that was always seen as the culprit, simply because it was so desirable at the time, but many other colors used arsenic as well. When the National Archives did testing on the William Morris wallpapers, all of the colors used arsenic to some extent. These colors were exceptionally beautiful, and up until this point, it was not something they could achieve without the use of arsenic.Rae: Are there still remnants of arsenic mining today?Hawksley: It’s funny because as I was doing my research, I was having a conversation with an older woman about my work. She had memories of growing up in the 1930s near a town that had had a working copper mine nearby. Her mother had told her not to grow any vegetables, because at that time they had realized the dangers of arsenic dust and knew it was in the soil. But for a long time, people living near copper mines had no idea that arsenic dust was falling on the soil, and so their crops would absorb all this arsenic dust. Lots of people were getting sick, but no one seemed to understand why. I’m sure that must have been the case with mining like this all over the world.

New samples produced

20160921_120549

Some of the prepared samples

The last weeks I was busy with preparing roughly 300 samples for the data base and the hardness measurements. Samples were made of eight different alloys, four different annealing times at 600°C in reduced atmosphere, cross-section and longitudinal section, and up to five different grades of deformation (cold rolling). And I have to admit that the rolling machine is just fantastic! The more arsenic the alloy contains, the harder it was to roll (not very surprising…) but I was fascinated by the squeaky sound the higher alloyed metal produced.