Day 2

Scaling the process up, I build an electrolytic cell with twenty graphite electrodes rather than yesterday's two. I use two car batteries wired up in series, rather than the small battery I used yesterday. As a result, oxygen streams off the electrodes, and I've little doubt that this larger cell will produce enough oxygen to make the oil lamps burn more brightly. I'll only need to increase the oxygen concentration in the lamp housing by a few percent in order to do the trick. At the moment though, I have a small problem; I'm losing a lot of the oxygen through leaking seals around the electrodes.

I can easily fix the leaks using epoxy resin (although the available resin will take up to 17 hours to be fully waterproof). I spend the rest of the day ensuring that the scaled-up cell is producing as much oxygen as possible, and that all of the highly flammable hydrogen gas generated at the other electrodes is vented off at a safe distance from the cell and Ellen's lamps.

Day 3

With a strict deadline of 11.45 for setting off in the boats to Bawe Island, I've got my work cut out this morning. The resin has set, and I'm confident that the scaled up cell will do the job. My only remaining problem is that I can't, for some reason, get a positive test for the oxygen that streams off the electrodes. The gas I collect should re-light a glowing splint, but I just can't get it to work. I know for sure that it's oxygen - what else could it be? - but I can't prove it. What on Earth is going on?

These challenges must all seem pretty easy from the comfort of an armchair; in practice, however, in the midday heat, under pressure, and working to an immovable tidal deadline, a simple thing like showing that the gas is oxygen isn't so straightforward. With hindsight, it boils down to the fact that I'm collecting the gas in the wrong way - a trivial mistake that will be picked up by anyone who knows a bit of Chemistry. I know that oxygen is slightly heavier than air, which is composed of 78% nitrogen, a lighter gas than oxygen. The method I actually used to collect the gas on camera was wrong. What a dingbat! I comfort myself by saying that anyone can make a mistake in such circumstances, but this is going to be such a public mistake. Best just to put the whole episode behind me.

Without being able to prove to Kate, on camera, that the gas I'm collecting is oxygen, there's no way I'll be allowed to take the scaled-up cell to Bawe Island, because my part of the challenge will, unfairly to my mind, be deemed to have failed. The decision is made more difficult because we're going to have to carry the lighthouse, my part of it as well as everyone else's, the length of the island (some 2 km) - as well as when, the tides dictate where we'll actually be able to land. By 1145, Kate and I agree to leave to the other scientists the final decision on whether my huge electrolytic cell goes to Bawe or not. We decide that we have enough to carry (and so it proves), and we should go without my oxygen generator. It's a tough decision, and one that I'm still not altogether happy about, but it's my mistake that's brought it about and I have to pay for it, however unfair I consider the outcome to be. Ellen's lamps will just have to do without my help. Despite this setback, the lighthouse works a treat - my oxygen wasn't really needed after all.

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Content last updated: 26/01/2005