Gherkins, or pickled cucumbers, may not be the most popular of vegetables, but they do have relatively unknown rare scientific qualities. They can become lightbulbs, albeit extremely smelly lightbulbs.
Richard Ellam, an associate of the Museum Association, used to be a museum curator. Now his illuminating gherkins are one of the bright lights of the Millennium Festival of Science and Innovation which opened in Derry yesterday and runs until September 30th.
"The practical potential of bulb gherkins is probably zero, but it's a great demonstration and it never fails to reduce audiences to hysterics," he said.
Mr Ellam, who now runs his own science presentation company based near Bath, praised the concept behind the Derry exhibition. "It's a great way to bring science to the community. We have got to keep people interested and enthused by science because it's simply great fun.
"You discover how the world works and that makes the world a much less frightening place. What gets professional scientists into science in the first place is the enjoyment they get from their work," he said.
He first heard about the possibility of lighting up gherkins a few years ago in the US. "I was standing in a lunch queue and someone told me that these crazy Americans could pass electricity through gherkins. I thought it was a joke, but in the true spirit of scientific investigation I had to try it for myself.
"When I came home I soon had otherwise sensible people all over the country sticking the ends of their electric flexes into gherkins and lo and behold when you switch them on you get an orange glow. Now this is a remarkably stupid thing to do and it is potentially lethal. Nobody should try this themselves because there is a very real danger they will be electrocuted.
"I have gone to great personal pains to ensure this experiment is as safe as it can be. A gherkin contains two things that make it light up - it is pickled in acid and there is also a lot of salt mixed into the acid.
"You have a heavy-duty mains lead, a large push-button switch which has a built-in safety feature, two sharpened brass spikes on an insulated platform and you just run the current through the gherkin, which is impaled on the spike. It really has to be seen to be believed.
"The light you get is orange, the same sort of light you get from sodium street lights. It's generated in a similar way by the electric current exciting the sodium atoms to give off light. The salt solution on its own isn't enough.
"The fact that there is an acid pickle solution there makes the vegetable conduct electricity. The acid is needed to allow the electricity to flow easily through the gherkin so there's enough power to excite the sodium atoms to get them to give off light," he said.