Kathy's Call of the Wild Diary

Production team Day 1

My plan is to make a periscope - which has to be watertight. Sounds easy enough, but ‘they’ won’t let me use a mirror - I have to make one.

I’ve silvered glass once before – and I know it’s quite a sensitive process. Too high a temperature, too dirty a surface, or too many impurities in the mix – and it won’t work. So I was pretty keen to start today: I need time to get it to work.

But we have no silver nitrate and no ammonia! Mike’s making the silver nitrate, and also the alkali I need (potash - from wood burned in the fire). But ammonia, another key ingredient, just isn’t available on the island (not since September 11, 2001  - it’s too useful for making explosives).

So we have to make that too - from everyone’s pee. Marvellous! You can just buy ammonia in the UK in supermarkets.

Mike’s been a complete superstar - getting on making all the chemicals. I helped boil the urine down and boil the potash too. But mainly I got on and prepared the rest of the periscope.

I cut lengths of plastic tube, and eventually found tubes that fit each other reasonably snugly. I cut bits of glass to fit into the bend of a right-angled tube. I wanted the biggest bit of glass that still could fit into the tube. After experimenting with cardboard + polystyrene sheets - I decided on the octagons …Now I just need to silver them. Am not wildly optimistic!

Used with permission Day 2

A long, hard, exhausting - but exciting day. More boiling down of urine and preparation of potash. Much fire-stoking. Exciting to finally get urea and mix it with the potash and boil … Couldn’t quite believe it when the gas that boiled off stank of ammonia. I had really wondered if we’d ever make it. Mike had tried to get it from so many other things (fertilisers, cleaning products etc.).

Also exciting to see the silver earrings dissolve in the nitric acid - quite amazing stuff.

So - after lunch - I was ready to go - having made up all the solutions I needed.

The ‘philosophy’ of Rough Science is that if we’ve shown we can make something (eg silver nitrate) - even if a small quantity - then they let us use more of it to finish a challenge. It may feel like cheating - but the thing is - it takes so long to actually film things - we genuinely don’t get a full 3 days to do the challenges. This approach means we can prove a principle, then get on and solve the challenge.

Even tho’ I’m really happy with this approach, it may still feel like nonsense to viewers that Mike makes about 2 cm3 of solution, even if concentrated, of silver nitrate - then I suddenly have buckets of it to make mirrors.

But we genuinely had made some and genuinely had taken hours to make ammonia - when the production team would have just given it to us if they could find the damn stuff!

Over lunch I was extremely sceptical about mirror-making. I had a really gungy solution of silver nitrate; some potash solution - which is sodium hydroxide when I really wanted potassium hydroxide; some sugar solution (instead of dextrose) and ammonia dissolved in water in some completely unknown concentration.

If I fail to make a mirror - it’s a pretty uninspiring challenge! Just a badly put together periscope.

Went off to the lab to experiment. Even Mike was less than optimistic - and he’s usually sure things will work.

The process is quite long… take some silver nitrate solution - add the ammonium hydroxide drop by drop until the brown stuff that formed dissolves again … add potash solution - half of it - add ammonium hydroxide slowly again.

This was the key stage - the mix is meant to go from dark brown to tea coloured. Instead, lumps of dark stuff sank to the bottom - and even after adding ammonium hydroxide it looked less like tea and more like dirty, clumpy water.

Finally I persuaded myself it looked a bit like tea, so I added the rest of the potash solution and began adding ammonium hydroxide again. This time it’s meant to go straw-coloured. Hopeless! Just the dirty water look again. The last step is to add sugar solution.

I added it - completely certain it wouldn’t work. Ellen had come along to see if we needed help. I said she might get a film crew along - if they were free - but I was pretty damn sure nothing would happen.

I shook a test tube, filled with the now black solution, I shook and shook and it just looked black … then suddenly - a slight silvering began. It felt like a miracle!

Silver - from dirty-looking chemicals and a complete absence of hope!

Repeated it once in a test tube - not as good this time. Tried to do it as before - but it really needs doing slowly. Then scaled up - from 4cm³ to more like 400cm³ of silver nitrate. Again unconvinced it would work … Trying to cover a big bit of glass - not easy. Did it twice - not brilliant - but half-silvered. Finished late and in the dark - not 100% they’re any good.

Production team

Day 3

Went to check the mirrors in daylight, with some trepidation …

Half silvered, as I’d thought, and fragile as hell. Instantly got my grubby fingerprints over them. Sigh!

But once in the periscope - the last one I made was amazing! I’d even run out of ammonium hydroxide solution last night before the reaction was really done - so I was just incredulous it had worked well enough. Ecstatic!

Had just a couple of hours to put it all together, glue in the glass, glue up the periscope and get out. After leaving it today I had a last check before leaving to get the boat and Jonathan peered down the end - and I stuck my head at the other end to grin at him.

Suddenly realised the other end of the periscope worked much better … I guess because at the shorter end - your eye is focused on distant things so you ignore the junk on the mirror that’s close up. From the longer end - you’re able to see the junk on the mirror - since it’s some distance away.

Raced around madly - getting another bit of perspex cut, sanding off the end first and gluing it on - hoping it would be dry in time for the challenge! EEK!

But it held and it worked. And it was completely amazing to see fish and coral so clearly underwater. Frankly though - the giant mirror-less tube with no bend was better - cos you could see so much more area … but we didn’t film that. The mirrored one - so painstakingly made - was too popular.