The Double Dangerous Book for Boys. Conn Iggulden

saw, then chiselled out the trench. Sandpaper was always on hand to smooth rough edges – another thing that is a lot easier with pine than, say, oak.

      We attached the two top pieces to the main bar before putting the holder onto the wall. Glue would work, of course, though screws are faster than waiting for glue to set. Held by single screws, they can obviously still move. That’s fine. If the screw is tightened, they’ll remain in place without needing adjustment.

       THE TRY SQUARES

      These tools – used for measuring and scribing angles – are held by two pieces. The first is a narrow bar of pine, held in place with two screws. In the centre, we cut and shaped a little tab of pine. On a single screw, the idea was that it could be moved open and shut if necessary, to remove the tool. That worked surprisingly well, though we had to take great care not to snap the thing along its length. To make it, we cut a narrow strip of pine, sawed it across to make a short piece, then sanded the edge to a curve by holding it against an electric sander.

       THE SPIRIT LEVEL

      We used a similar set-up to hold one of the spirit levels. For this, though, we decided the central tab shouldn’t move. We used two pieces to build out a ‘shelf’ to the right width to hold the level, then attached the final tab using a shallow trench chiselled out, so that it couldn’t turn. It’s probably a bit fussy, but it’s an old spirit level and we didn’t want it to fall off just because someone slammed a door.

       COPING SAWS

      Coping saws are useful. They cut around corners and are excellent for delicate work such as dovetail joints. (The narrow blades do snap, though, so keep spares. There’s nothing worse than having your last blade snap on a Sunday afternoon, with no shops open.)

      For these, we cut a piece of pine as you can see in the cross-section image. Hold in a vice and make two saw cuts that meet. Leave enough room for a couple of screws to attach it to the wall and you have a nice wooden lip.

       THE HAMMER AND RIP SAW

      The big 23oz hammer and the rip saw are held with pegs. For this we went to a DIY store and bought pine dowel, then sawed it into pieces. We needed a much bigger drill bit to put the holes in the plywood sheet. We held the saw to the wall and marked the positions where the pegs would go – using a spirit level to make sure the saw hung straight down as well. With a little sanding and shaping, we glued the dowel pegs in place, tapping them in gently with the wooden mallet – and then hitting them really hard when ‘gently’ had no effect whatsoever.

       THE CHISELS

      The most complicated holder is the one we made for the chisels. We shaped two opposite side pieces with a jigsaw. We cut a trench in each one to support the shelf, but had no screws long enough to go through the wide bottom section, so added a lower bar. We were able to attach that with screws at both ends and then also attach it to the plywood behind.

      The chisels drop down into square holes we marked at regular intervals. A lot of careful marking, measuring and pencilling was required to make these. Pleasingly, we used the chisels themselves to cut their own slots.

      We also tapped a few nails in. Hammers can have a small hole drilled in the wooden shaft and be hung from a nail. Rulers and spirit levels usually come with a hole to hang them. None of this is expert-level carpentry. It’s all pretty rough and ready, but the results work. The tools are all within reach, exactly where we left them last time. It makes life easier.

      Finally, we attached a shelf of pine on another wall with about twenty holes drilled in it, to hold pliers and screwdrivers. It’s enormously useful and it helps to keep clutter off the workbench from the original Dangerous Book – still going strong.

       INTERESTING CHEMICAL REACTIONS

      Courtesy of the author

       Chemical reactions can be extremely dangerous. Read these for interest, but either don’t try them or get an adult involved and accept that trying them comes with risk. You should wear goggles, masks and gloves when using potentially toxic chemicals.

      One difficulty of writing the first Dangerous Book was getting hold of chemicals. Even for something simple like growing crystals, finding a reliable source for copper sulphate or potassium permanganate was almost impossible. Since then, the website eBay will supply all sorts of interesting chemicals – for a price.

      As a test, we bought pieces of sodium and potassium. These metals react so violently with water that they have to be kept under oil – just the moisture in air will cause them to combust. You may have seen them used in school chemistry labs: tiny pieces dropped into a bowl of water to fizz around and glow purple or orange. In comparison, dropping a large piece into a drinks bottle half-full of water will cause it to explode after two or three seconds. Do not try that. If you do try that, make sure you run a long way and are safely behind something; learning about the properties of sodium and potassium is interesting, but it should not be at the expense of eyes or fingers. Please be clear about this: the man who invented the stunt kite became a recluse when he heard a boy had been carried off a cliff by one of his kites – a death that would not have happened if not for his invention. If in doubt, don’t do it.

      Without resorting to the internet, some things found around the home can also be made to react in interesting ways. Of course, sometimes a reaction is just setting something on fire.

      1

       FLAMING BUBBLES

      This first one should not be tried without adult supervision. It involves large bursts of flame and, frankly, of the eight or ten times we tried it for this chapter, we almost set the house on fire twice and actually did burn all the hair off our fingers and forearms. It was spectacular, but come to think of it, just do not try this inside. Or at all.

      We used a kitchen bowl half-filled with water, some liquid soap, a box of matches and some butane gas of the sort that refills cigarette lighters. It’s available from any supermarket.

      Upturn the butane gas in the water and press the nozzle against the bottom of the bowl. The gas will form large bubbles in the soap – exactly like a bubble bath, but, you know, filled with highly flammable gas.

      Wet your hand in cold water. Do not forget to do this. Move away from the bowl. On the two occasions we nearly set fire to the kitchen, it was when we forgot to move clear of the bowl and the butane-filled spatters of foam on the kitchen counter.

      Touch a match to the bubbles. The flame burns bright and