Heroines in Jane Austin novels are always in need of sal volatile. “Young ladies are delicate plants,” as Mr Woodhouse said in “Emma”. They react to any distressing situation with a genteel faint, so they always carry a pretty little bottle of smelling salts. I’m afraid that I am not very genteel. Sal volatile always reminds me of a disastrous experiment I carried out while I was an archaeology student.

I was working on chipped stone tools from the very earliest part of the Stone Age, around 300,000 years ago. For some reason that I can’t remember now, I wanted to take photographs of the details on the surfaces of a lot of these flakes. Flint is very shiny and I couldn’t get good photos because the camera flash reflected so badly off the surface of the flakes. One of my more scientific colleagues suggested coating the flakes with a matt film. He produced a nifty little device which allowed me to heat crystals of ammonium chloride i.e. sal volatile in a glass bulb over a Bunsen burner. This produced curls of grey vapour which could be blown gently over the flints through a rubber tube, coating them with a non-reflective grey film. I felt like a real scientist with my Bunsen and my tubes of chemicals. It’s a pity that the experiment was a complete failure. However, I probably inhaled enough smelling salts to prevent me fainting for the rest of my life.

“Diamonds are forever” goes the song. Not quite true, as I proved during an even more disastrous experiment with flint tools. Another part of the project involved trying to replicate the effect on flint flakes of being tumbled along in a river. Tumbling wears down the edges of the flakes and smooths the surfaces.

I bought a little machine used by gemstone enthusiasts, which had a drum turned by an electric motor.  You put the flint flakes into the drum and tumbled them for different periods of time with different combinations of sand and water and pebbles. However my little tumbler proved inadequate and I somehow got permission to use a bigger one at the Geological Museum in South Kensington. The staff there suggested that I should number the individual flakes and kindly lent me a diamond-tipped drill to do it with. Flint is mostly silica, which is an extremely hard substance, although in theory not as hard as diamond. In theory. I must be the only student ever to have worn all the diamonds off the end of an expensive diamond-tipped drill. I slunk from the laboratory in shame, and my days as that kind of experimental scientist ended there.