Day 3 — Monday, 12 July

We have to get up really early and head down to the harbour to board an inflatable dinghy to take us to film our 'landing' on Capraia. We're shooting things out of sequence, as is usually the case with these projects. This question of continuity is a problem for the production team, not for us, thank god.

When we get to the pre-determined landing place, there's a 2m swell and a rising tide, which is not going to make things easy for our boarding party. With Drew filming our arrival from the cliff-top, and the second film crew in another inflatable alongside, we decide that, for safety's sake, only two of the scientists (and Kate) should attempt the landing.

Drew, the cameraman filming us from the cliff-top, has been up since 4am, poor lamb. He was despatched to film the sun rise just in case we need an early morning shot for use in the editing suite. It's still only about 8am, but it seems like we've been up for hours. God knows what Drew feels like. After several attempts at getting our inflatable close inshore, we at last succeed in shooting some acceptable footage of the landing.

Then it's straight back to the harbour and up to the cliff-top to join Drew, so that he can film us 'clambering up the cliffs on our way to the prison'. Viewers would be surprised at what's involved in filming the shortest of sequences like this. It's taken us 5 hours to shoot something that will be on screen for just a few seconds. While the others head back to the Prison, Vanessa and I set off to find some olives to prepare what's called a 'carrier' oil for our insect repellent.

When we get back to 'the Gulag' (as I'd started to call it), it's obvious that some slight tension has developed between Jonathan and the other Mike. They're no longer working together, and have separated to work on different elements of the same challenge – to locate our position by determining our latitude and longitude. I'm glad I'm not involved with that one. I wouldn't have a clue where to start.

The pair of them seem to be making some kind of progress, despite the difference of opinion I'm told that they'd had earlier. Jonathan's sawn an aluminium saucepan in half and connected it up to a lot of wires, and Mike's constructed a crucifix. Have they really fallen out that badly? Would one of us be in for a troubled time tonight? What exactly is Mike's cross for?

Anna, our plant biologist, has spent much of the afternoon feeling underused. She is, like me, in some awe at what the boys were attempting to do; make a radio and quadrant, in order to calculate our position. A radio of all things! From next to nothing!! That's magic!

The problem for Anna is that her specialism is still to be tested, and the magic she's to work will be magic of a very different, but no less practical, kind. At the moment, she can't see that that is the case, however, and, understandably, she feels a little surplus to requirements. I think I understand why this is. To boost her confidence, she, like me, needs to achieve a positive result, and tomorrow I'm going to help her achieve it.

Day 4 — Tuesday, 13 July

Today's big challenge — to help Anna isolate the essential oils from some twigs of rosemary that she'd found on her walk round the island yesterday afternoon. This aromatic oil would come in handy when we come to make soap for Programme 4 (another job for the Team chemist). Anna also says that rosemary oil's good for helping one's concentration and intellectual powers; something we'll all need over the next few weeks.

To extract the essential oil, I know we'll need to use a standard laboratory technique called steam distillation. Although I've never carried out a steam distillation before, I know the principles behind the process, and am prepared to have a go. We need a means of generating steam over an open fire, and passing it through a container stuffed with the rosemary leaves and twigs.

An outlet from this container needs to lead to an improvised air condenser (a simple glass tube, with a 2.5cm bore), which should be enough to cool the steam and oil vapour mixture back to water and oil, respectively. We also need to be able to see and control the amount of steam generated, and a demijohn found in one of the rooms will be just right for the purpose – or so I thought.

I'm not altogether sure that the glass will stand up to being heated over an open fire, so I consult Jonathan, who agrees with me that it's worth a try using it as our steam generator. At least the glass will allow us to see the rate of boiling, and we can raise or lower it over the fire to control the steam output accordingly.

As in any laboratory, improvised or not, safety is a key issue. Kate has sensibly brought with her several sets of safety spectacles, and everyone in the 'lab' is ordered to put them on before we start work. There's to be no eating in the 'lab', and every precaution will be taken to minimise the possibility of accidents.

An eye has to be kept on everyone's safety and well-being. For example, the room I've chosen to use as the 'lab' has plenty of ventilation, from an open, barred window at one end, and a large hole (open to the beautiful, clear-blue sky) in the ceiling. The resulting through-draught will be ideal, particularly as we'll be creating quite a lot of smoke from the wood fire, not to mention the possibility of noxious fumes.

Our confidence in the glass demijohn proves short-lived. No sooner has the water in it started to boil, than there's an almighty crack, and hissing – the demijohn has shattered, and its contents spilt all over the fire, putting it out. Doh!! Back to the drawing board then! Let's hope they don't use that sequence in Programme 1!

It's already late afternoon, so we'll have to wait till tomorrow, the final day of this challenge, before we can have another crack at the steam distillation. The rest of the day is spent scouring the prison and its grounds for something that we can use to replace our ill-fated demijohn.

Day 5 — Tuesday, 13 July

Having set it up, our re-designed 'Capraia' mark II steam generator, proves much safer than its predecessor. Because the can in which we're now heating the water is made of metal, rather than glass, there's no way we can accurately tell how vigorously its contents are boiling.

This makes it even more crucial that we build-in some way of literally letting off steam if the water in the can boils too vigorously. Conveniently, a second outlet on the can allows us to release any unwanted pressure build-up. So, out of our initial failure and disappointment comes an improved version of the apparatus. We're ready to rock and roll again!

Vanessa, Anna and I grow more excited as droplets of water condense on the inner surface of our improvised air condenser. After a short while, droplets of oil can also be seen condensing out along with the water.

In five minutes we've collected enough condensed liquid to see that two layers have formed in the collecting vessel; an upper layer comprising the rosemary oil, and a lower layer of water. All we have to do is to decant off the upper layer, and, hey ho, there's our rosemary oil!

Anna had written about the extraction of essential oils using steam distillation in one of the many books she'd authored. However, this is the first time that she's actually seen it done (like me). She seems as pleased as Vanessa and I with the outcome of our first challenge, and it's still only lunchtime on the third day. We've managed to extract a serviceable quantity of rosemary oil from a bundle of dry twigs and leaves. Although there's been little real chemistry involved, this is what Chemistry's about – the transformation of one thing into another. Magical.

I feel like some latter-day alchemist. In fact, our 'lab' has already taken on the appearance of an alchemist's den..........and the smell. After only one day, we've made our improvised work-space smell like every other chemistry laboratory I've ever been in. Now that's an achievement!

What we have to do now is to find a carrier oil to which we can add our precious rosemary oil extract. We'd noticed on our way up to the prison on the first day, that Capraia was covered in olive trees, so the choice is an obvious one. But how on earth do you extract the oil from olives?

Our first attempt, which involvs Vanessa treading the olives like grapes doesn't work at all; the olives are out of season and far too hard for that method to be effective. My proposed alternative — crushing the olives between two house bricks — isn't much better. In the end, we resort to brute force. Crushing the olives to a pulp in a bucket, using an improvised mallet. Although hard work, it's effective, and before long we've squeezed enough oil out of the olives to serve as a carrier for the essential oil.

Anna, Vanessa and I are so proud when we come to present Kate with the fruits of our three days' labour — an insect repellent produced entirely from the natural resources of our temporary island home.

We've met our first challenge. We can go home comforted by the knowledge that at least we've had some success for the first of the four programmes. But what will the remaining three programmes throw up? Would we be able to meet the remaining challenges as easily as we have this first one? Presented with our initial success, Kate has an unsettling look of mischief about her. What does she know that we don't?

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Major funding for Rough Science was provided by the National Science Foundation. Corporate funding was provided by Subaru.