The Mystery of the Hairy Vases

by Capucine Korenberg

Dr Pilard was having a quiet coffee early one morning at her desk. She was a scientist and had been working at the British Museum for eleven years. She loved her job. There were so many beautiful or interesting objects to see. Every time she wandered into a gallery, she would come across something she had not noticed before: for example a delicate Ancient Egyptian comb made of ivory or a rare silver coin. Sometimes though, she would discover something that would blow her mind... Once she spotted a striking necklace with large shiny blue and green beads in the European Jewellery Gallery. When she came closer to the showcase, she realised that the “beads” were actually hummingbirds’ heads. What a shock! Imagine having dead birds around your neck!

Dr Pilard’s mobile phone started vibrating. It was Mr Curran, the curator in charge of the Roman galleries at the British Museum. He was panting and seemed terrified. “Dr Pilard, I need your help! I don’t know what happened to some of the Roman vases: they are covered with white hairs... And seventeen look like they have exploded! Could you please come to Basement E1025 immediately?”
Dr Pilard left her coffee on her desk and raced down the spiral staircase towards the basement store. She loved mysteries. One of her hobbies was to read detective stories. Basement E1025 was deep underground and to access it she had to go through a maze of dark corridors and staircases. Dr Pilard had developed a fear of these underground stores, but she summed up her courage and carried on. After what seemed hours, she reached the store. There were several vases of various sizes laid on a table in the middle of the room. Mr Curran was sweating, but a look of relief swept across his face as soon as he caught sight of Dr Pilard. He pointed at the vases on the table: “Look at them!” They were covered with long white hairs and their surfaces had completely crumbled. Dr Pilard had never seen anything like this before...  She took some of the white hairs to analyse in her lab while Mr Curran told her what had happened. The entire collection of Roman vases had been moved to Basement E1025 two months ago. Previously, all the vases were stored in a small room next to the museum’s boiler. Because of the hot water pipes, it was always very hot in this room, as hot as Spain in the summer! The store was dirty and in 1927 the museum staff had put the vases in wooden boxes to protect them from dust. Nobody had ever seen white hairs on them. Back in her lab, Dr Pilard switched on the scanning electron microscope. It would allow her to see what the white fur looked like close up. She stuck some of the white hairs on a stub and put it in the microscope’s chamber. At high magnification, the hairs looked like snowflakes, which indicated they were small crystals. Dr Pilard switched on the X-ray detector. When a sample is shot with electrons, it emits X-rays. By measuring the energy of the X-rays, the detector would tell her what the sample was made of. The image of the hairs disappeared from Dr Pilard’s screen and was replaced by a graph with several peaks. It showed that the fur contained carbon, oxygen, calcium, chloride and nitrogen. Many things are made up of these elements and can have very different properties. Dr Pilard needed the help of her colleague, Dr Hazel, to identify the mysterious crystals. She grabbed her phone. “Dr Hazel, could you please run an XRD test on a white powder I have found on a Roman vase?” She heard Dr Hazel sigh. Dr Hazel was a brilliant, but rather grumpy, scientist.

“Dr Pilard, is this matter so urgent that you need to disturb me in my lab? I am really busy examining the paints on an Egyptian coffin right now. I cannot work properly if people keep interrupting me! Only two months ago, a student came to my lab uninvited looking ford plastic gloves.
- Dr Hazel, I promise you I would not call you if it was not an emergency. Seventeen Roman vases have exploded after being moved to Basement E1025 and I must stop the rest of them exploding...
- Exploding vases! This does sound like a bit of an emergency. Could you pop over to my lab in nine minutes?”
At 3.42 pm, Dr Hazel had identified the white crystal as thecotrichite. It usually formed when sea salt was near an acidic gas. Dr Pilard thought about this... Many Roman vases had been found in shipwrecks at the bottom of the sea. They would contain sea salt. The vases had also been kept in wooden boxes for almost a hundred years. Wood releases a little bit of acidic gas. This is why a wooden box kept closed for several days smells of vinegar when you open it. So it made perfect sense that the vases contained thecotrichite. But Dr Pilard could not figure out why the white hairs had formed on the vases after being taken out of the wooden boxes and moved to Basement E1025.
Dr Pilard consulted some scientific books. Salts only make damage if they can move within an object. For salts to move, they had to absorb water from the air. Ha-ha! She thought she had solved the mystery! She called Mr Curran. “Mr Curran, I think I know what happened to the vases. I need to check out a few things out to be entirely sure, but let’s meet in the store in two hours and I will explain everything.” Dr Pilard went to lab 3. Her colleagues there recorded the temperature and humidity of the air all over the British Museum using small wireless sensors. “Good morning Miss Wilson. Could I please have a look at your records?” A young dark haired woman with red lipstick smiled at Dr Pilard. Miss Wilson loved working with the scientist. They sat together at a desk and looked at some graphs, comparing the amount of
humidity in the old store and Basement E 1025. Dr Pilard thanked Miss Wilson and went directly to the Roman Vases Store. Mr Curran was already there waiting for her.
“Mr Curran, you know that the vases spent a long time at the bottom of the sea before coming to the British Museum. Underwater, they became impregnated with sea salt.
- Is this what the white fur on the vases is? Sea salt?
- No, it is more complicated than that. Listen to me. When the museum staff put the vases in wooden boxes more than a century ago, they did not realise that it would have terrible consequences. Wood contains a very small amount of acid, which evaporates slowly with time. Inside the wooden boxes, the acidic gas crept inside the vases and reacted with the sea salt to form a crystal: thecotrichite.
- Theco what?
- The-co-tri-chite. Yes, I agree with you, it is very difficult to pronounce! I would have chosen a different name myself... Anyway, as long as the air in the store was dry, the crystal remained dormant within the walls of the vases. And I have checked with Miss Wilson: the old store was so hot that it was as dry as The Sahara Desert.
- What about here?
- Well, it is not so hot and the air gets damp at times, especially when it rains outside. So this is what happened: on a rainy day, the crystal sucked up water from the air. Exactly like when you add a drop of water to sugar. With the water, the crystal moved towards the surface of the vases. This was still fine and did not cause any damage. But, this changed as soon as it stopped raining: then, the water inside
the vases’ walls evaporated and crystals formed. With more and more cycles of rainy and dry weather the crystals grew bigger and bigger inside the vases. They formed hairs, which pushed against the walls and made them crumble. This is why the Roman vases look like they are exploding...
- Gosh, this is absolutely terrible! Can we do anything to stop this?
- Well, we need to keep the air inside Basement E 1025 dry. So I suggest we bring a dehumidifier here. It will remove the water from the air and the crystals will stop growing.
- Thank you so much, Dr Pilard. You have solved the mystery of the hairy vases! Let me buy you a coffee.
- That would be lovely. There is a cup of coffee on my desk, but I guess it would have become cold by now!”