30-06-2025
Moving suspended gold particles to Royal Society is a delicate job
It is not far from the Royal Institution to the Royal Society. Less than a mile. But this week, as Charlotte New travelled between the two — holding some bottles of pinkish liquid containing a little sprinkling of gold — every foot was planned.
The taxi driver knew the preferred route, knew not to brake suddenly, and knew that New, head of heritage at the Royal Institution, would be very upset with jolts.
'We do not want jiggling,' she said before the transportation. 'There is to be no jiggling.'
She would not tell The Times when she was leaving though — for insurance purposes it had to remain secret.
Only once in the 170 years since Michael Faraday accidentally made an odd suspension of gold particles have these, his colloids, left the Royal Institution, the scientific organisation famed for its Christmas lectures.
Then, it was because of the blitz. The country's most precious treasures were moved to the slate mines of Wales. These odd bottles, which glow ruby in the light, spent several years out of the light, alongside old masters, the Magna Carta and first folios of Shakespeare.
This time, they are being moved for an exhibition at the Royal Society, Britain's national scientific academy. There, they will appear alongside other colloids as researchers investigate how a phenomenon discovered by mistake by Faraday, long considered an optical curiosity, might have practical value.
The colloids were created as part of attempts by the Victorian polymath, most famous for his work on electricity, to make ever-thinner sheets of gold. He was investigating, among other things, the optical properties of the gold. To make gold leaf as thin as possible, he washed it in acid.
But then he noticed that this run-off was itself interesting. When he shone a light through it, it scattered with a ruby glow. He realised it was hitting tiny particles of gold, suspended in the liquid. The particles are small enough that over almost two centuries they have in some of the bottles stayed suspended — held aloft by the movement of water molecules. Others have settled. No one is sure what shaking will do.
'When we clean them, we use paint brushes,' New said. 'We dust around them, and not very often.'
The Royal Institution is taking the risk of moving them, along with Faraday's notebook, as part of its 200th anniversary celebrations of its Christmas lectures, as well as Faraday's discovery of benzene.
At the Royal Society's summer exhibition, opening from July 1 to 6, they will not merely be there as part of scientific heritage. They will be exhibited alongside some modern colloids, with potentially important applications.
Dr Aliaksandra Rakovich, of King's College London, said: 'Faraday cared about colour. He was curious about that, and that's what he investigated.'
But, today, his work is seen as a landmark in nanotechnology, and among the first investigations into the properties of very small particles.
Dr Simon Freakley, of the University of Bath, said: 'Gold is perceived as being inert. When you make these very, very small particles of gold, they actually become incredibly reactive.'
In particular, if you shine a laser at them then they get extremely hot. This can be a low-energy way to facilitate difficult reactions.
Freakley and Rakovich are looking at ways to harness the reactive properties of colloids in industrial processes and also for tasks such as removing air pollution.
Faraday's colloids will, hopefully, not be reacting though.
We do know, now, that they made the journey unharmed. By shining a laser, the Royal Institution confirmed the properties were unchanged during the second journey of their lives.
Now New just has to get them back.
