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The Mystery of Iridescence in Glass

AnnaPokorska20 May 2019

This is the second part on a series on ‘Iridescence’. You can read the first part here, or return and read an introduction to colours, as well as individually about the colours blue, red, yellow, and green

If you’ve ever wandered through a museum displaying ancient artefacts, chances are you were amazed at the quality and artistry displayed in glass objects of that time. The   has some incredible pieces shining with iridescent colours:

Left: glass weight from the Fatimid period; Middle: glass fragment from the Roman period, possibly part of an eye amulet; Right: glass fragment from the late Roman period (Petrie Museum: UC13298, UC22744, UC67914).

However, despite the undeniable talents of ancient glassmakers, this particular effect was not intentional or even achieved during production. In fact, iridescence found in ancient glass is a result of weathering of its surface caused by burial.  The weathering process itself depends largely on the burial conditions such as heat, humidity and type of soil, although the chemistry of the glass, determined by the purity of raw materials and their compositional ratio, also plays a part. The iridescence is produced when alkalis, or soluble salts, are leached from the buried glass by slightly acidic water present in the soil. This in turn causes the formation of very fine layers which can delaminate or even flake off creating a prism effect.

But it wasn’t until the very end of the 19th century that the iridescence of ancient glass was replicated by Louis Comfort Tiffany (1848-1933), the son of Charles Tiffany – the New York jeweller. He began his career as an aspiring painter but soon realised that his true potential was in interior decoration. It is generally thought that during his extensive travels Tiffany became inspired by the glasswork and mosaics of antiquity and devoted to the idea of restoring stained glass to its former glory by striving to achieve the same standards of beauty as the ones present in antique masterpieces[1]. Prior to the twelfth century, stained glass works were executed with differently coloured glass pieces as opposed to the later technique of painting on clear glass, which dulled it considerably and created a flat two-dimensional effect. Tiffany’s experiments with glass during the 1880s completely revolutionized the look of the medium and in 1894 he patented favrile glass[2]. By adding different or same shades of colour into the hot mixture Tiffany created a material different from other iridescent glasses as the effect was not just confined to the surface but part of the glass itself.

Tiffany Glass and Decorating Company was established in 1892 in New York and began producing its first favrile glass objects 1896, examples of which can be found in the Victoria and Albert Museum collection as well as other major museums, particularly in America.

Favrile glass objects produced by the Tiffany Glass and Decorating Company between 1896 and 1902 (Image: © Victoria and Albert Museum, London).

Left: “The Flight of Souls”, Tiffany stained glass window which won first prize at the 1900 Paris Exposition, now at the Wade Memorial Chapel, Cleveland, Ohio (Image: CoffeeDoc03); Right: Hanging Head Dragonfly Tiffany lamp from the Art Institute of Chicago collection (Image: mark6mauno).

Tiffany won first prize for the above stained-glass window using his new material at the 1900 Paris Exposition and continued to use favrile for other products, including his famous lamps. Being the innovator that he was, he also carried on experimenting with the medium, eventually developing many other, equally impressive, types of glass such as opalescent, streamer, fracture, ring-mottle, ripple and drapery. But that’s for another time!

[1]     Bing, S Louis C. Tiffany’s Coloured Glass Work, in Artistic America, Tiffany glass and Art Nouveau, Cambridge (Mass.); London: M.I.T. Press, 1970

[2]     The original trade name was actually fabrile, which was derived from an Old English word meaning ‘handcrafted’.

Question of the Week: How do dogs recognise other dogs?

Cerys RJones30 April 2019

From Great Danes and Dogue de Bordeauxs to miniature Dachshunds and Chihuahuas, man’s best friend comes in a variety of shapes and sizes, so how can they recognise fellow dogs even when they all look so different?

Dogs come in a variety of different shapes and sizes, featuring Jess the black Labrador, Jewell the miniature Dachshund, Percy the Bichon Frise, Luna the Dogue de Bordeaux, Scratch the Jack Russell Terrier, and Spud the mixed-breed. (Engager’s own photos)

The Kennel Club recognises 211 different breeds of dogs but with different coats and mixed-breeds, there are by no means 211 dog-shaped moulds. Despite this, your dog can decipher between a Bichon Frise and a lamb instantly. This is in part due to their impressive sense of smell which they use to smell the hormones secreted by other dogs. Not only do they have a large nose cavity, which contains a folded surface covered by the sensing organ that is up to 23 times larger than in humans, they also have a vomeronasal organ in the roof of their mouth for detecting smells [1]. This means dogs can smell up to 10,000 times better than humans [1].

Seven domestic dog skulls on display in the Grant Museum (Accession number: Z2909)

Dogs’ ability to recognise different chemicals through their sense of smell has been used by humans to sniff out drugs, explosives and even illnesses such as cancer and diabetes. But is this the only sense dogs rely on to recognise other canines? A study from 2013 tested nine dogs’ ability to correctly identify other dogs from pictures [2]. The dogs were shown two images: one of a dog (from a set of 3000 pictures of different breeds, including mixed-breeds) and one of a non-dog animal, which included cats, cows, rabbits, birds, reptiles and even humans. On command, the dog participant had to correctly distinguish between the images and place their paw on the picture of the dog. All nine dogs successfully chose the images of the dogs over the images of non-dogs the required 10 times out of 12. The study concluded that dogs could “form a visual category of “dog pattern”” ([2] page 647); however, it did not allow the researchers “to determine which dog morphotypes or which species were easier to discriminate” ([2] page 648). As the dogs were successful at distinguishing between dogs and other animals from photographs alone, it is clear that they don’t solely rely on a sense of smell.

Hair curlers with a hunting dog on from the Petrie Museum (Accession number: UC8529)

Although varying highly in appearance, from the colour of their coat to the length of their snout, dogs use both their senses of smell and sight to identify others. Exactly which visual cues are required is still unknown. One thing we know for certain is, regardless of how they look, they’re all good dogs!

 

Bibliography

[1] Miklosi, A., (2018) “The Dog: A Natural History” Ivy Press, Brighton

[2] Autier-Derian, D., Deputte, B.L., Chalvet-Monfray, K., Coulon, M., and Mounier, L., (2013) “Visual discrimination of species in dogs (Canis familiaris)” Anim Cong, 16, pp 637-651.

Simply the Bes: 7 reasons Bes should be your favourite Egyptian god

Cerys RJones6 April 2019

Forget Anubis, Horus and Ra, Bes is the bes(t) Egyptian god around! His figure may not land him any jobs striding down our catwalks (he is short and has a large protruding stomach) but his distinctive and playful face won the hearts of Ancient Egyptians and even spread to the Roman empire, Cyprus, Syria and more. Here are 7 reasons why you should love Bes as much as the Egyptians did:

1) He protects your home
Like our modern day ‘live laugh love’ wall stickers, Ancient Egyptian families often decorated their home with images of Bes. His figure is found on a range of household objects including mirrors, cosmetic jars and even the headboard of beds where he’d protect the person sleeping.

Wooden cosmetic-spoon featuring Bes at the British Museum. Museum number EA5954.

2) He loves music and dancing
If you could only have one Egyptian god at your house party, you’d choose Bes. What better party guest than one who can provide great music and dance all night whilst simultaneously protecting the house? You can see figurines of Bes dancing at the current exhibition in the Petrie Museum called ‘Shake, Rattle and Roll: Sounds of Roman Egypt’. He is often depicted playing a tambourine or harp or dancing near other musicians, and some performers even tattooed his image on their bodies.

Dancing Bes alongside seated group of musicians in the Metropolitan Museum of Art. Accession number: 23.6.79.

3) You can wear him on your jewellery
The collection in the Petrie Museum contains many strings of beads with amulets of Bes, such as the blue faience bead of Bes’ head (read more about the bluefaiencein Arendse’s blogpost.). These were probably worn for protection but make for a great statement piece too.

Amulets of Bes in the Petrie Museum with accession numbers UC37498 (top) and UC38008 (bottom). Engager’s own photo.

4) There are vessels made in the shape of his head
It’s impossible to miss the abundance of pottery vessels in the Petrie Museum featuring Bes’ face. They’re so charming and always popular among the visitors at the museum, featuring heavily on the #PetrieMuseumInstagram hashtag.

Pottery vessel with Bes’ face decoration in the Petrie Museum. Accession number: UC8902. Engager’s own photo.

5) He makes you smile…and he’s supposed to!
When ancient Egyptian babies would unexpectedly laugh or smile, many Egyptians believed that Bes was somewhere in the room pulling funny faces. He was a protector of mothers, children and pregnant women, and wall paintings of Bes have been found in rooms that were associated with children or childbirth.

Column Capital in the form of a Bes-image in the Metropolitan Museum of Art. Accession number: 23.2.35. Engager’s own photo.

6) He had a distinctive style
As can be clearly seen on the amulets, Bes often wore a headdress made of feathers. He also was depicted wearing a lion skin cape, although after the New Kingdom he often opted for a leopard skin cape instead (very on trend!). However, the Romans adopted him as a military deity and often depicted him in their legionary costume.

Bes with a tambourine in the Metropolitan Museum of Art. Accession number: 23.6.16

From the ultimate party guest to splashing his face on vases, Bes is the best Ancient Egyptian god. Initially as a protector of the Pharaoh, Bes became the god of the people, looking after their homes and their children. He was a multifaceted god, who was a serious protector and a merry entertainer. In fact, the only temple believed to have been dedicated to Bes was next to a vineyard so he could protect the grapes and oversee the production of wine! Many relics still exist today featuring his distinctive figure. Visit the Petrie Museum where you can find many Bes related artefacts including several vases, amulets and figurines!

Colours of Ancient Egypt – Yellow

AnnaPokorska20 February 2019

This is the fourth post in the Colours of Ancient Egypt series; here you can read the introduction, here all about the colour blue, and here about the colour red.

Due to its availability in several different forms and shades, yellow was present in many aspects of ancient Egyptian art and decoration, from painting to pottery.

Fragment of a vessel (Petrie Museum, UC25325; Photo: Anna Pokorska).

Pottery vessel containing rough pieces of pale and deep yellow pigment (Petrie Museum, UC59746).

Just as men’s skin was painted red in Egyptian painting, women’s can be distinguished by its yellow colouring, which we can see in a fragment of a statue made out of yellow jasper possibly depicting Queen Nefertiti or Queen Kiya and dated ca.1353–1336 BC.

Fragmentary head of a Queen in yellow jasper, from the 18th Dynasty (Metropolitan Museum of Art, NY).

Yellow was also used to mimic gold in works where the use of the precious metal wasn’t possible. The most prevalent yellow pigments in ancient Egypt were derived from natural ochres and had the same properties as their red equivalents — but they were by no means the only source of the colour.

Painted linen mummy shroud painted with red lead, carbon black, orpiment and Egyptian blue pigments (Petrie Museum, UC38058).

Orpiment was a common yellow pigment with a rich lemon or canary yellow shade. It is an arsenic sulphide and occurs naturally in small deposits as a product of hydrothermal veins, hot spring deposits and volcanic sublimation, although nowadays it can be easily obtained artificially. The arsenic content makes it highly toxic and the sulphur will darken lead-based pigments if used together in a mixture.

Closely related to — although not as widespread as — orpiment is an orange pigment called realgar which can often be found in the same deposits. Despite its toxicity, it was the only orange pigment available until chrome yellows and oranges were introduced in the beginning of the 19th century. An interesting feature of realgar is that prolonged light exposure turns it into a yellow compound called pararealgar without changing its elemental composition.

In addition, Egyptians were able to synthetically produce a highly toxic lead (II) antimonate, also known as Naples yellow. It was often used as an enamel colour from about 1500BC, although it didn’t appear in painting until the Renaissance. As one of the oldest produced artificial pigments it was highly toxic and provided a warm orange shade of yellow. Interestingly, a mineral of the same chemical composition, called bindheimite, exists in nature but wasn’t used to create the pigment. Instead it was made by a calcination of a lead compound (such as lead white) with an antimony compound (e.g. potassium antimonate). A 19th century recipe recommends mixing the ingredients, placing them over a gentle heat and then gradually increasing the temperature. After approx. 5 hrs the calcination is complete, and the resulting product can be ground in water with an ivory spatula (because iron can react with the powder and change its colour). The shade of the pigment could also be manipulated by changing the proportions of the ingredients. Lead antimonate is very stable to light exposure but due to the lead content will turn black on contact with hydrogen sulphide (e.g. in air).

Why were so many dangerous substances used as pigments for so long, especially as harmless clays were so abundant? Although their toxic effects were known, the depth and brilliance of the lead and arsenic compounds made the natural iron oxides appear rather dull and brownish in colour by comparison. In fact, even the pigments that strove to replace them — cadmium, chromium and cobalt yellows which appeared during the 19th century — are all harmful to some extent, and it wasn’t until the development of organic pigments (based on carbon and hydrogen) that we overcame this issue!

 

Young’s Inequality: The erasure of women’s names in history

Cerys RJones13 December 2018

Young’s Inequality is a powerful result in mathematics, named after William Henry Young, a British mathematician who was president of the London Mathematical Society and a Fellow of the Royal Society. However, I recently learned that much of the work published under William’s name was actually in collaboration with his wife, Grace Chisholm Young.

Grace Chisholm Young studied mathematics at Girton College, Cambridge after being awarded the Sir Francis Goldsmid scholarship. She achieved the equivalent of a first-class degree in her exams, and even decided to take the final year exams for Oxford; she received higher marks than all of the Oxford students and became the first person to achieve a first in any subject from both the University of Oxford and the University of Cambridge. Grace moved to Germany to study for her PhD under the supervision of Felix Klein (famous for the Klein bottle). She subsequently became one of the first women to officially be awarded a doctorate in Germany (read more on Dorothea Schlözer, who received her degree from Gottingen in 1787, and Sofia Kovalevaskaya, who received hers in absentia in 1874).

Klein bottle, first defined by mathematician Felix Klein

After completing her PhD, Grace moved back to the UK and married William, who had been her tutor whilst at the University of Cambridge. William was appointed a professor at several universities whilst Grace cared for their children, studied for a medical degree and simultaneously wrote papers for herself and for William. Grace converted William’s research notes into academic papers, correcting his mistakes and completing his proofs. Their daughter stated that “much of their collaboration was behind the scenes of the very large number of papers published by W. H. Young”. William was aware of the inequality of women at the time and occasionally mentioned Grace’s contributions in footnotes such as one which stated “Various circumstances have prevented me from composing the present paper myself. The substance of it only was given to my wife, who has kindly put it into form. The careful elaboration of the argument is due to her.” Private letters from William to Grace also discussed the nature of their joint work. In 1902, he wrote “The fact is our papers ought to be published under our joint names, but if this were done neither of us get the benefit of it” adding “everything under my name now, and later when the loaves and the fishes are no more procurable in that way, everything or much under your name.”

In time, Grace began to be acknowledged for her work. In 1906, they published a textbook on set theory together and William wrote “any reference to the constant assistance which I have received during my work from my wife is superfluous, since, with the permission of the Syndics of the Press, her name has been associated with mine in the title page.” Grace also began publishing papers in her own name from 1914 and was awarded the Gamble Prize at Gerton College. William, however, received greater recognition for their collaborations and was awarded the de Morgan medal from the London Mathematics Society and the Sylvester prize from the Royal Society. Women were not eligible to become fellows of the Royal Society until 1945, just a year after Grace’s death.

Grace has since received recognition for her many important papers on differentiation and derivatives, as well as for the Denjoy-Saks-Young theorem, which is named after her. Furthermore, in a letter addressed to her sister, Grace wrote “I liked being incog. to the outside world, and felt I had the perfect right to do so, husband and wife being one… I don’t want to be mistaken for the modern ambitious female, ambitious for herself and her own glorification.” Grace never yearned for recognition for herself and may have even disagreed with the message of this blogpost.

Although  there are numerous other stories of women’s successes being hidden under the guise of a man in history, steps are continuously being made towards equality. In 2018, there are 124 women fellows in the Royal Society, although this is only 8.5% of the total number of fellows. According to the Higher Education Staff Statistics for the UK in 2016/17, there are 5050 female professors in the UK (24.6% of the total number of professors in the UK). Whilst these numbers appear to be steadily increasing, there is still a long way to go to see women represented equally in academic positions.

 

The information in this blogpost came from the following papers:

[1] Claire Jones (2000) “Grace Chisholm Young: Gender and mathematics around 1900”, Women’s History Review, 9:4, 675-693

[2] Patricia Rothman (1996) “Grace Chisholm Young and the Division of Laurels”, Notes and Records of the Royal Society of London, 50:1, 89-100

 

Colours of Ancient Egypt – Red

AnnaPokorska4 December 2018

This is the third post in the Colours of Ancient Egypt series; here you can read the introduction, and here all about the colour blue.

Red was an easy colour to obtain in ancient Egypt as naturally red minerals, or clays, were abundant. In fact, they were already used as pigments for painting in pre-historic times. Of the earth pigments, as they are often called, ochre was used for red colouring. Like others, it is an iron oxide but gets its red shade from a mineral hematite, which can be naturally present in varying quantities. Another way of obtaining the pigment is by heating the more common yellow clay to produce what is called ‘burnt ochre’.

Painted wooden stela showing man Ihefy adoring hawk-headed Horus (Petrie Museum, UC14695).

In ancient Egyptian painting we find the red colour often used to distinguish gender, as men’s skin was often painted red[1]. We can see an example of that in this painted wooden stela from the Petrie Museum.

Less obviously, red ochre was also popular in cosmetics such as rouge and lip colour. In fact, those pigments are still found in beauty products today due to their ready availability, stability and non-toxicity. However, perhaps the most surprising application of these materials is actually medicinal. The Ebers Papyrus, one of the oldest and most important medical texts from ancient Egypt (dated 1550 BC), prescribes ochre clays as a cure for any intestinal or eye problems.

However, minerals were not the only source of red colourants. Ancient Egyptians were also able to tint their textiles using madder or kermes carmine dyes. The former was derived from the root of a madder plant, rubia tinctorum (see below).

Madder plant (Image: Franz Eugen Köhler).

It was one of the most widely used natural red dyes until the development of synthetic equivalents in the 19th and 20th century. In fact, some madder-dyed cloth was even found in Tutankhamun’s tomb. On the other hand, kermes carmine was made from wingless insects found on certain species of European oak trees. Like madder it was used both as a textile dye and a lake, which is a pale pigment obtained by precipitating a dye onto an inert colourless substrate such as chalk. Kermes’ deep crimson shade made it a very popular colourant for centuries.

So far, I’ve mainly talked about pigments and dyes used for decoration, but I would be remiss if I didn’t mention at this point one of my favourite objects in the Petrie collection:

Fragment of a composite statue from Amarna: right ankle and heel, in red jasper (Petrie Museum, UC150; Photo: Anna Pokorska).

This is a right ankle and heel in red jasper, part of a full-size composite statue from Amarna, dated to the 18th Dynasty. I’ve often stopped in front of it imagining what the statue would have looked like whole. I have to admit that I previously assumed the sculpture to have been entirely made of red jasper, which, in my mind, looked incredible. However, that was not the case; only the exposed flesh would have been carved from red jasper (thus depicting a male figure), while the rest of the statue was likely made from Egyptian alabaster, limestone or wood. The Metropolitan Museum of Art in New York has fragments of a king’s head made of the same material and dated to the same period. In fact, some of the fragments come from the Petrie collection which makes me wonder if they were perhaps part of the same statue.

Fragmentary head of a king in red jasper, from the 18th Dynasty (Metropolitan Museum of Art, NY).

We may never know. But one thing is certain: even though we’ve since been able to create many synthetic red colourants of various shades, natural red pigments used by the ancients remain as popular as ever.

 

[1] Lorelei Corcoran, Color Symbolism, in ‘The Encyclopedia of Ancient History’, Edited by Roger S. Bagnall, Kai Brodersen, Craige B. Champion, Andrew Erskine, and Sabine R. Huebner, Blackwell Publishing Ltd. (2013), pp. 1673–1674

The Plagues of Egypt

Hannah BPage23 October 2018

For my blog post this week I am starting a new series based loosely on the Plagues of Egypt. The idea came to me while I was working in the Grant Museum and was thinking about possible connections between the Grant and the Petrie Museum of Egyptian Archaeology. For some reason as I was stood next to the insect cabinet, the plague of locusts was the first thing that came to mind.. and conveniently, I have already written a blog post about the 2nd plague of frogs. Before I launch in I must note briefly that I don’t particularly wish to talk about religion or religious texts. Instead I will use the 10 plagues to discuss some (hopefully) interesting zoological and sociocultural phenomena that link the two museums.

So, what are the 10 Plagues of Egypt?

  1. Water turning into blood
  2. Frogs
  3. Lice
  4. Wild animals
  5. Diseased livestock
  6. Boils
  7. Thunderstorms of hail and fire
  8. Locusts
  9. Darkness for three days
  10. Death of the firstborn

The first plague of water turning into blood is an interesting one to start with, but the topic of the two liquids is very pertinent to both collections. Water has an incredibly important role in the ideological and cultural landscape of ancient Egypt. The waters of the Nile were the lifeblood of ancient Egyptian society. It provided vital irrigation for farming, transport through the kingdom, and was linked closely with ideology and religion in Egypt. The Greek Herodotus is recorded as calling Egypt the “gift of the Nile”, implying that Egypt itself was born from the river—this further develops an idea I have discussed in a previous blog post: that the Nile is deeply connected with fertility. With this in mind it is not difficult to see how devastating the idea of water turning into blood would be for Egyptian society.

One papyrus from the twelfth dynasty (c.1991-1803 BCE) interestingly states that the “river is blood“, which has caused some debate over the occurrence of the plagues in Egyptian history. However, the most probable explanation is that during the harsh flooding of the Nile the disturbed red river silt would create this phenomena.

Blood as well as water was also symbolically significant to the Ancient Egyptians. Wine was given as “blood of the Gods” during certain religious offerings, something akin to the Christian symbolism of using wine as the blood of Christ, and the deity Shesmu is also linked with blood, being the lord of wine and the “great slaughterer of the gods”.

It is also not difficult to connect the Grant Museum with water and blood as they are both vital components to many living creatures on earth. For this post I wish to focus in on one of my favourite water dwellers in the museum and one that has a deep connection with ancient Egypt. This mammal can certainly displace a lot of water and coincidently produces a fluid over its skin that is often called blood sweat. The hippopotamus, known as a “river horse” by the ancient Greeks secretes a substance called hipposudoric acid. The liquid is red, which gives it its colloquial name, but it is neither sweat nor blood. In fact the secretion is an example of an evolutionary masterpiece—a natural sunscreen! This fluid is very much needed due to their skin being exposed in blistering high UV environments (and being a redhead who works in sub-Saharan Africa- I can fully appreciate this)! As well as the blood sweat creating UV protection it is also a very good antiseptic, which is useful as hippos can be extremely aggressive animals.

Fig 2. Hippo skull in the Grant Museum of Zoology (Catalogue no. Z32)

Sadly, the hippo is no longer found in Egypt but in dynastic times it was a hazard to boat travellers along the Nile and was present in ideological and cultural symbolism.  The deity Taweret was often depicted in the form of a pregnant hippo as she represented fertility (like frogs!). Hippo figurines are also found on ancient Egyptian sites (Fig 3) and hippo tusk ivory was used to make pendants, amulets and sculptural pieces.

Fig 3. Blue glazed faience hippopotamus (Petrie Museum Catalogue No. UC45074)

As you can see, water and blood were and still are incredibly important cultural symbols, most probably due to their inescapable connection to the natural world and to life and death. It really is no wonder that that these themes come up time and time again all over the world.

I hope you have enjoyed my first foray into the Plagues of Egypt as much as I have… I’m quite excited about what direction they might take my research in next!

Colours of Ancient Egypt – Blue

AnnaPokorska16 October 2018

This is the second in the Colours of Ancient Egypt series; if you want to start at the beginning, click here

The colour blue has already featured in a couple of posts in this blog (e.g. check out Cerys Jones’ post on why the Common Kingfisher looks blue) but it seems impossible to me to discuss colour, especially in Ancient Egypt, and not start with blue. Arguably, blue has the most interesting history of all the colours, which can be attributed to the fact that it is not a colour that appears much in nature – that is, if you exclude large bodies of water and the sky, obviously. Naturally occurring materials which can be made into blue colourants are rare and the process of production is often very time-consuming. In Ancient Egypt, pigments for painting and ceramics were ground from precious minerals such as azurite and lapis lazuli; indigo, a textile dye now famous for its use in colouring jeans, was extracted from plants.

 

Left: two pieces of azurite (Petrie Museum, UC43790); Right: lapis lazuli (Image: Hannes Grobe)

However, all the above-mentioned colourants presented issues which limited their use. Azurite pigment is unstable in air and would eventually be transformed into its green counterpart, malachite. Lapis lazuli had to be imported from north-east Afghanistan (still the major source of the precious stone) and the extraction process would produce only small amounts of the purest colourant powder called ultramarine. Finally, indigo dyes can fade quickly when exposed to sunlight.

And yet it seems that the Ancient Egyptians attributed important meaning to the colour blue and it was used in many amulets and jewellery pieces such as the blue faience ring, lapis lazuli and gold bracelet or the serpent amulet from the Petrie Museum collection (below).

From left to right: blue faience ring with openwork bezel in form of uadjat eye (Petrie Museum, UC24520); lapis lazuli serpent amulet (UC38655); fragment of bracelet with alternative zig-zag lapis lazuli and gold beads (UC25970).

Therefore, the race to artificially produce a stable blue colourant began rather early. In fact, the earliest evidence of the first-known synthetic pigment, Egyptian blue, has been dated to the pre-dynastic period (ca. 3250 BC)[1]. It was a calcium copper silicate (or cuprorivaite) and – although the exact method of manufacture has been lost since the fall of the Roman Empire – we now know that it was made by heating a mixture of quartz sand, a copper compound, calcium carbonate and a small amount of an alkali such as natron, to temperatures over 800°C.

 

 

 

 

 

 

 

 

Fragment of fused Egyptian blue (Petrie Museum, UC25037).

This resulted in a bright blue pigment that proved very stable to the elements and was thus widely used well beyond Egypt. In fact, its presence has recently been discovered on the Parthenon Marbles in the British Museum due to its unusually strong photoluminescence, i.e. when the pigment is illuminated with red light (wavelengths around 630 nm) it emits near infrared radiation (with a max emission at 910 nm).

After its disappearance, artists and artisans had to make do with natural pigments and, being the most stable and brilliant, ultramarine became the coveted colourant once again. In fact, during the Renaissance, it is reputed to have been more expensive than gold and, as a result, often reserved for the pictorial representations of the Madonna and Christ. And so, the search for another replacement was back on. But it wasn’t until the early 1700s that another synthetic blue pigment was discovered, this time accidentally, by a paint maker from Berlin who, while attempting to make a red dye, unintentionally used blood-tainted potash in his recipe. The iron from the blood reacted with the other ingredients creating a distinctly blue compound, iron ferrocyanide, which would later be named Prussian blue. Naturally, other man-made blue pigments and dyes followed, including artificial ultramarine, indigo and phthalocyanine blues.

However, it wasn’t quite the end of the line for Egyptian blue, which was rediscovered and extensively studied in the 19th century by such great people as Sir Humphry Davy. And not only are we now able to reproduce the compound for artistic purposes, scientists are finding more and more surprising applications for its luminescence properties, such as biomedical analysis, telecommunications and (my personal favourite) security and crime detection[2].

References:

[1]  Lorelei H. Corcoran, “The Color Blue as an ‘Animator’ in Ancient Egyptian Art,” in Rachael B.Goldman, (Ed.), Essays in Global Color History, Interpreting the Ancient Spectrum (NJ, Gorgias Press, 2016), pp. 59-82.

[2] Benjamin Errington, Glen Lawson, Simon W. Lewis, Gregory D. Smith, ‘Micronised Egyptian blue pigment: A novel near-infrared luminescent fingerprint dusting powder’, Dyes and Pigments, vol 132, (2016), pp 310-315.

Colours of Ancient Egypt – Introduction

AnnaPokorska18 August 2018

When viewing exhibitions of objects from ancient Egypt (or any ancient civilisation for that matter) we are used to seeing the beige and grey appearance of bare stone. Indeed, we have come to appreciate the simplicity and purity of ancient sculptures, reliefs and carvings, perpetuated by the numerous plaster casts made and distributed both for research or as works of art in their own right (case in point – the Plaster Court at the Victoria and Albert Museum).

However, this is quite far from the truth. In fact, colour was not only common but of great symbolic importance in Egypt. This is hardly surprising as we use colour to communicate every day even in the modern era (with the most obvious and striking example of the traffic light system, or the wearing of black in many cultures to signal mourning). Although some traditional meanings will have changed over the centuries and varied between cultures, the principle still remains and is widely studied and exploited in a fascinating way in such fields as psychology, marketing and advertising. But I digress…

Let us return to ancient Egypt. To date, many attempts have been made to restore the original colours of artefacts. One such example is the virtual restoration of the Temple of Dendur at the Metropolitan Museum of Art in New York where experts have a created a colour projection to be overlaid on top of the damaged hieroglyphs. An article on the whole project, called Color the Temple, can be read here.

Some people object to these types of intervention, sceptical of how well they recreate and represent the work of the artist, especially if little physical evidence of the original colours in a particular artefact exists. And indeed, we must always be careful when it comes to any type of restoration to take it only for what it is – someone else’s idea of what the object would have originally looked like (often dependent on the restorer’s skill). Although they might still have a way to go, I personally find these virtual restoration techniques intriguing and full of potential. They certainly help my imagination and understanding of the ancient Egyptian civilisation.

But we can find authentic and undamaged examples of colour even in the Petrie Museum collection. One of the first objects one sees when entering the main exhibition is a limestone wall block fragment from the pyramid of King Pepy I at Saqqara, its beautiful hieroglyphs tinted in green (below).

Wall block fragment from the pyramid of King Pepy I at Saqqara. (Petrie Museum, UC14540)

Painted wooden stela of Neskhons, wife of the High Priest of Amun Pinedjem (II) making an offering to Osiris. (Petrie Museum, UC14226)

 

While on the other side of the display is a painted, rather than carved, wooden stela of Neskhons, wife of the High Priest of Amun Pinedjem (II) making an offering to Osiris (above).

Egyptian artists would have had at their disposal mostly pigments made from grinding common (as well as some not-so-common) minerals and earths. Hidden away in the Petrie Museum storage is a drawer full of exactly those kinds of pigments (below).

Pigment drawer in storage at the Petrie Museum. (Photo: Anna Pokorska)

 

The yellowed typed note reads:

‘The pigments used by the ancient Egyptians for their paintings have been analysed and are mostly made from naturally occurring minerals, finely ground, or from natural substances.

Black – some form of carbon, usually soot.

Blue – originally azurite, a blue carbonate of copper found locally. From the IVth Dynasty on artificial frit was used composed of a crystalline compound of silica, copper and calcium.

Brown – generally ochre, a natural oxide of iron.

Green – powdered malachite (a natural ore of copper), and an artificial frit analogous to the blue frit described above.

Pink – an oxide of iron.

Red – red ochre, a natural oxide of iron.

White – either calcium carbonate (whiting) or calcium sulphate (gypsum).

Yellow – yellow ochre, an oxide of iron and less often orpiment a natural sulphide of arsenic.

The pigments were pounded in to a fine powder, mixed with water to which a little size, gum or albumen was added to make the whole adhesive.’

Unfortunately (or perhaps fortunately), this subject is too broad and interesting to fit into a single blog post and I’ve decided to explore it further, perhaps expanding beyond Egypt and the ancient times. We shall see where this journey takes me, but I hope you will join me as I investigate individual colours in my future posts.

 You can now read about the colours blue and red.

Consanguinity and Incest in Ancient Egypt

AlexandraBridarolli16 August 2018

My curiosity was piqued during one of my turns at the Petrie Museum. Facing all these artefacts, traces of dynasties of pharaohs, I was suddenly reminded of the stories of incest and marriages between brother and sister which were common in ancient Egypt among the ruling class. More recently, the topic was brought up again by another visitor. I was then told about Akhenaton’s androgynous appearance that could have been a result of the incestuous practices of the time. This practice seems to be a common thing and these stories made me immediately think of the Greek and Roman gods and their intricate family-love relationships. With this thought came then one question: why would pharaohs marry their sister, mother and other relatives? To act as living gods? To preserve the purity of their blood?

Fig. 1: Limestone statuette of Akhenaten, Nefertiti and Princess (Tell el Amarna). [Petrie museum, UC004]

Many others questions followed: If incest was accepted in ancient Egypt among the ruling class, was it tolerated by the whole population? What makes it unacceptable in Western countries today? Health? Morality? Are marriages among siblings and/or first cousins still allowed nowadays in some countries? And what are actually the risks of incestuous relations?

From ancient Egypt to the Habsburg family in Europe, throughout history cases of consanguinity — mainly among members of the ruling classes — are numerous. It is surprising that the practice continued for as long as it has when religious and civil laws started to forbid it and when the risks associated to this practice started to be known; from the 5th century BCE, Roman civil law already forbade couples from marrying if they were within four degrees of consanguinity (Bouchard 2010). From the half of the 9th century CE, the church even raised this limit to the seventh degree of consanguinity and the method of calculating degrees was also changed. More recently, modern philosophers and thinkers argued that the prohibition against incest was a universal phenomenon, the so-called incest taboo . But this theory seems contestable in view of the Egyptian case.

So why is it that incest was accepted and practised in ancient Egypt and more recently among members of the royal family such as the Habsburg (16th-18th century)? And how did science shed the lights on family relationships, incestuous practices and the diseases resulting from them?

Let’s first take the case of the 18th dynasty, the first dynasty of the New Kingdom of Ancient Egypt.

Incest in Ancient Egypt: the case of the 18th Dynasty

There is an abundance of evidence showing that marriages or sexual relations between members of the “nuclear family“ (i.e. parents, children) were common among royalty or special classes of priests since they were the representatives of divine on Earth. They were often privileged to do what was forbidden to members of the ordinary family. During the Ptolemaic period (305 to 30 BCE) the practice was even used by King Ptolemy II as “a major theme of propaganda, stressing the nature of the couple, which could not be bound by ordinary rules of humanity” (Chauveau, M.).

Fig. 2: Alabaster sunken relief depicting Akhenaten, Nefertiti, and daughter Meritaten. Early Aten cartouches on king’s arm and chest. From Amarna, Egypt. 18th Dynasty. [Petrie Museum, UC401]

But let’s go back to the 18th dynasty (1549/1550 BCE to 1292 BCE). In 2010, a team of Egyptian and German researchers analysed 11 mummies dated from the 18th dynasty which were closely related to Tutankhamun (Hawass, Zahi, et al.). The mummies were scanned and DNA extraction on bone tissues was carried out. The information they could get from these analyses enabled them to identify the mummies, determine the exact relationships between members of the royal family, and to speculate on possible illnesses and causes of death.

The results of the DNA analyses show that Tutankhamun was, beyond doubt, the child born from a first-degree brother-sister relationship between Akhenaten and Akhenaten’s sister (see Fig. 3). Moreover, the authors provided an answer to the androgynous appearance of Akhenaten. They actually showed that the feminized appearance exhibited by the art of the pharaoh Akhenaten (also seen to a lesser degree in the statues and reliefs of Tutankhamun) was not related to some form of gynecomastia or Marfan syndrome as suggested in the past. Neither Akhenaten nor Tutankhamun were likely to have displayed a significantly bizarre or feminine physique. The particular artistic representation of persons in the Amarna period is more probably related to the religious reforms of Akhenaten.

However, the incestuous relationship between Akhenaten and his sister may have had other consequences. Pharaoh Tutankhamun suffered from congenital equinovarus deformity (also called ‘clubfoot’). The tomography scans of Tutankhamun’s mummy also revealed that the Pharaoh had a bone necrosis for quite a long time, which might have caused a walking disability. This was supported by the objects found next to his mummy. Did you know that 130 sticks and staves were found in its tomb?

Fig. 3: Genealogical tree showing the relationship between the tested mummies dating from the 18th dynasty (Source: Hawass, Zahi, et al.).

 

Fig. 4: Scans of Tutankhamun feet (Hawass, Zahi, et al.)

 

Incest and common people

This article on consanguinity and incestuous marriages could easily finish here. We learned that incest was practised in ancient Egypt for strategic reasons, in order to preserve the symbolism which associates the pharaoh to a living god. We also saw how science could help us in unravelling the true stories lying behind myths, speculations and rumours.

This could be almost perfect but the incest taboo is more complex than this. As observed by Paul John Frandsen, “in a society (such as ancient Egypt) where nuclear family incest is practised there is no discrepancy between what is licit among royalty and in the populace”. Indeed, contrary to what is often admitted incest was not only reserved to the ruling class. In Persia and ancient Egypt, incestuous relationships between members of non-royal nuclear families also existed (Frandsen P. J.). This shows that incestuous relationship in the nuclear family could be more than just propaganda and that other reasons might have motivated this practice. It has been argued that this was done for economic reasons as endogamy could have been a means to keep the estate undivided and/or avoiding paying bride price. However, these arguments have been dismissed. Up till now, there is thus no reasonable explanation for the lack of incest taboo in ancient Egypt and Persia.

Keep an eye out for my next post, where I’ll talk about incest in the Habsburg royal family and King Charles II of Spain (also called “the Bewitched”)!

 

References (and read more!)

Bouchard, Constance Brittain. Those of My Blood : Creating Noble Families in Medieval Francia. University of Pennsylvania Press, 2001.

Chauveau, Michel.MmNm. Egypt in the Age of Cleopatra : History and Society under the Ptolemies. Cornell University Press, 2000.

Hawass, Zahi, et al. “Ancestry and Pathology in King Tutankhamun’s Family.” JAMA, vol. 303, no. 7, 2010, pp. 638–647.

Frandsen, Paul John,MmNm. Incestuous and Close-Kin Marriage in Ancient Egypt and Persia : an Examination of the Evidence. Museum Tusculanum Press, 2009.