The desire to play with fire stems from several places. Firstly, curiosity usually drives a young person to begin experimenting. Fire is fascinating, not least because of the amount of social baggage it is afforded. One of the first things we are taught is "Do not play with fire!", along with "Do not play with knives!" and "Don't talk to strangers!". Strangers don't really hold much fascination, after all they're just people. But fire and knives are peculiar artifacts, one a force of nature made available through artifice, the other a tool of purely human design, but unique amongst tools in its intended design - to harm and hurt people. As I have hinted, their prohibition lends further fascination, but that quickly subsides. What really seperates a curious schoolboy from a true pyromaniac is the perception of a third phenomenon: Power.
A young child is a relatively powerless creature, or so (s)he feels, and while most children are happy to carry on with their lives exploring their burgeoning social network and people skills, some get a taste for power, the feel of a ciggarette lighter or box of matches in their hands causing a flutter in the chest and a rush in the head, which, thinking about it, feels an awful lot like love.
We're not talking about a love of fire here, we're talking about a love of power, so merely setting fire to stuff isn't really much of a rush. That kind of behaviour suggests different kinds of psychological issues. No, our pyromaniac wants to control nature, subdue the flame. So begins a life of petty crimes against the establishment of their household.
Enough prose though, it should be clear by now that I am one such Pyromaniac, though I dislike the implication of mania, instead preferring something like "Pyrology". My Latin isn't that great, forgive me. The pyrologist is interested in the boundary where household physics is pushed beyond the boundary of what is appropriate for the home. Fast things, hot things, cold things, changes of state, curious shapes, the nature of destruction and change. They will construct and refine small arms, such as knives, swords, bows, arrows, spears, along with interesting targets and methods of measurement and callibration. They will also get very, very good at putting out fires. Furniture, clothing, hair, paper, chemicals, equipment. They will also get a keen sense for where the boundary lies. The boundary between, say, compressed butane and liquid petrol. A packet of powder retrieved by crushing a solid block of model rocket fuel, and a tampered commercial firework. The pyrologist has great respect for the boundary. The one who lives anyway.
Didn't I start that paragraph with "Enough prose though,.."? Ok, I mean it this time. What follows is a bunch of cool experiments that the budding pyrologist, pyromaniac, pyroetc can play with, impress friends with, and perhaps, use to burn down their parents house. Enjoy!
Plastic Bottle Spirit Engine!
This was probably my greatest invention, and just before we go further, yes I know all these things have been done before, but I did come up with this one independently, and it's cool, and no-one else has mentioned it so nyaah. Right, this works on the principle of good combustion requiring fuel and air. If you have a good mix, then you get a good burn, and depending on your fuel, that means a decent amount of hot gas. If you manage to keep the heat in, then the hot gas is hotter, and so bigger. So get a cola bottle, drink the cola, spray an aerosol into the bottle for about half a second or less, then proceed to 'breathe' the bottle a few times, by squeezing half the air out, then forcing the bottle back into shape (to suck air back in again). This ensures a good balance of fuel and air, and mixes them quite well too. Don't wait too long, but place the bottle on its side on the floor (preferably outdoors on flagstones for the first few tries). Be sure that there is nothing important behind the neck of the bottle for about 50cm before holding a naked flame, at the end of a short length of stick (about 30cm) at the open neck of the bottle. All going well, the fuel-air mixture will catch, and the engine will roar into life with anything from a prolonged whoosh to a loud WHUMP, and the bottle will travel away at speed. How much speed and how far depends on the burn parameters, which in turn depend on the fuel and air.
Once you've done a few test fires you'll find yourself getting closer to the action until you're igniting the engine whilst holding it. It's quite safe. That is to say, it's not safe, it's quite safe. You'll see the flame front travel down the length of the bottle from top to bottom, using up the fuel, and you'll see the funky jet flame that emerges from the nozzle. You'll also notice the bottle rapidly rise in temperature, usually not too hot to touch, but enough to melt the thin plastic so that the bottle shrivels up slightly on each burn. Eventually the bottle stops shrinking, but the volume is significantly reduced, lowering burn duration, and the non-uniform shape increases friction for free-travelling burns. I got pretty experienced with this kind of experiment until I was happy performing launches indoors, and impressing peers. However beware that jet flame. One time it caught the tip of my index finger, instantly crisping it. Oddly it didn't hurt much at all, and new skin grew back after a couple of weeks. Be careful with vertical launch attempts, they're awkward and rarely work, and it's easy to burn yourself. You can however have great success by attaching two or three engines in parallel, the only hard bit is igniting them simultaneously. The best fuel I tried was butane from a lighter-refill can. Liquid spirit fumes also work, eg meths, alcohol. In theory petrol will work, but petrol burns very hot, and would probably melt through and ignite the bottle. Avoid petrol.
Hold a gas lighter ready in one hand. Make a fist with the other. Then, keeping the little finger tightly curled, slightly uncurl each of the other fingers until you have a small cavity in your hand. Be sure not to make any gaps between fingers. Hold the nozzle of the lighter pointing in through the hole at the top of your fist-bubble between your index finger and thumb with your lighter-hand and depress the button to allow gas to flow into the cavity. Remove the lighter and seal the bubble with your thumb. Then reopen the thumb-gap very slightly and spark the lighter there (spark only, no gas), just before upturning and opening your hand. If you get it right, the spark ignites the gas which burns with a small flame at the thumb-hole. The flame does not travel into the cavity because there is no air left in there, only fuel. When you open your hand air rushes in and the rest of the fuel catches, creating a fireball in your hand. With practice and misdirection you can turn this into a fairly cool party trick. If you are getting burned between your thumb and index finger (the site of the pilot flame) then lick this area to moisten it first, and you'll be ok.
Ok, this is old news I know, but it really needs to be included. You need a box of matches for this one. Remove a match. The lighting strip is a runway, and the head of the match is a wheel. Hold the box with the runway upward between the base of your thumb and the middle joints of your fingers of one hand. The thumb floats above the runway, like the 'tower'. Place the wheel near the closest end of the runway towards the tower, and the other end of the match should be held by the pad of the tower (thumb). With the other hand, position the nail of the index or middle finger against the tip of the thumb and apply tension, ready to 'flick'. Aim to strike the match close the the wheel with the striking finger, and with moderate pressure holding the wheel against the runway, the box held firm, the match just off vertical (leaning forward) release the flick. The wheel scrapes along the runway as the match is pushed along, hopefully igniting just before it flies away, bursting into flame in mid air, and leaving a cool spiral or loop of smoke in its wake. If the match lands on something flammable beware that it may still be alight on landing.
I developed the spirit engine (above) into a pretty useful gas torch, useful for directing very high (relatively) temperature flame with decent precision. Again, empty a cola bottle. The cap of the bottle is to be your nozzle this time, so drill a hole in the middle of it. You'll come to adjust the hole diameter (or number of holes) after some experimentation. Also drill a small hole in the base of the bottle. Many bottles have five or so 'prongs' on the base to make them able to stand and at the center is a tough bit of thick plastic. Make the hole here. Next you need fuel. This time we have to use an aerosol - either a compressed fuel such as butane lighter refil or if you can stand the smell and stickiness, deodorant or hairspray etc. I strongly advise the gas refill though. Don't try to adapt a can of gas designed for a camping stove. The valve is not the right kind and tampering with it could cause a major explosion. Death. You don't want that. If the can you're using has a finger plunger remove it, exposing the little tube. It connects to a valve. Press it to make gas come out, but you knew that anyway.
So the idea is that you plug the can into the hole in the back of the bottle. Problem is that the valve pipe on the can is usually just a uniform diameter, which makes it hard to trigger it when inserted into the bottle. However, butane lighter refill cans usually come with a bunch of stepped adaptors which lend themselves nicely to the task of interfacing the bottle and the can with a step to allow you to trigger the valve. It's important that the interface adaptor makes a tight fit with the bottle, because you want to limit the amount of gas that leaks from the back of the bottle. There will be a naked flame at the front, and there's a risk of a flame returning to the rear of the bottle. Now, there's more risk of this happening if you remove the can and leave the rear hole open, especially if you pressurise the bottle, but you can plug this with a finger or a piece of plasticine. On the other hand, while you can leave the can in situ, decreasing the risk of escaping gas igniting, the potential consequences are significantly worse, since the returning flame is headed for a can of high pressure flammable gas. So the first method is safer, and being a responsible pyrologist, you're not afraid of a little extra flame - it's things like explosions that you're afraid of. So fill from the can, plug with plasticine, and if it does catch at the rear, check the can hasn't caught somehow, chuck it, then smother the unwanted flame.
Now, all of this talk of explosions might sound a bit dangerous, but this is actually a pretty safe contraption. The principle is that you have a cache of fuel with an open nozzle where the fuel meets air. Ignite it here and it should keep burning, while the pressure keeps it flowing. Being a plastic bottle, you can give it a squeeze to up the flow, or keep it going when the pressure drops, until you can plug the can back in and get some more fuel in. Safety tip number 2: don't ignite as soon as you've put fuel in. If there's enough air left in the bottle then you have a flammable mixture in there and the flame front may pass into the bottle through the nozzle and mess things up. An explosion is unlikely but possible, and again, you don't want that at all. So instead let the gas run for a bit before you start it up. Better if you squish the bottle before you feed the gas in, and 'blow it up'. Hmm, bad choice of words. Anyway, the nozzle flame is small but hot, and fairly easy to control. Plus if you do get a blow-back, you can see it coming through the transparent bottle and get anything explosive out the way. It's unlikely that anything worse than the bottle overheating and shrinking (like the spirit engine does) will happen.
You can make several different nozzles out of different bottle caps, such as different size holes, spares for then they inevitably melt (but not for a while), and I found a 'shower-head' cap with several holes useful for larger areas of controlled heating. You can melt lead with this thing so that means it can exceed 327°C, so you can also melt tin (232°C), and I reckon zinc at 419°C is within reach of a developed version. Bear in mind that this design does not feature oxygen mixing before the nozzle, so potentially much greater temperatures are possible, but you have to be careful with this kind of thing. Don't just go cutting intake holes into the side of the bottle. If you want to develop this further, look at how Bunsen burners and so on are designed. But you'll want to upgrade the nozzle to metal or something more heat resistant than plastic.
Gas Flame Thrower!
This is a much less controlled artifact, and a lot more dangerous, but perhaps a bit more fun. You need a metal tube, over a metre in length. One of those chromed clothing rails will be suitable, just make sure it's a tube, not a curled sheet. At one end, attach a metal tablespoon using wire or metal cable ties. Get some metal gauze or some such to wrap over the spoon. At the other end you need to make some kind of metal covering with a hole that you can plug a plastic interface adaptor into (as per the back end of the gas torch (above)). I used a computer blanking plate with the screw slot as the interface point. It's important to be able to remove the can without fuss (again, we're using a butane lighter refill can as our fuel source of preference). Put cotton wool in the spoon, pour some slow burning spirit (such as methylated spirits) into the cotton wool and wrap the metal gauze over. Ignite the spoon. This is the pilot. Beware that burning spirit fuel will drip out of the spoon if tipped. Once alight, position the gas can at the interface point, ensure that there is no obstacle to gas flow down the tube (actually you should probably do that step before you set fire to anything), then push the valve fully open. It's important not to be gentle with the gas, or for that matter, to use an excessively depleted can. The pressure will blow the air out of the tube before the gas. The tube must contain only fuel and no air while the can is in place. Fire for quick bursts only though, as the tube will continue to get hot a few seconds after the fuel supply is cut. At the same time, the interface end will be getting cold because of the dropping pressure of the gas. You may want to wear a heatproof gauntlet. When you cut the gas, the big flame will die away, and air will start to enter the tube. Clear the gas can imediately. Get it right away from the tube and make sure that nothing important is within a metre in a line with the interface end of the tube. When enough air is in the tube, the remaining fuel will ignite and a rapid burning flame front will shoot from the hot end to the cold end with a satisfying WHOOP sound. The pressure of the exhaust gases causes a blast at both ends of the pipe, which often extinguishes the pilot. The pipe will suddenly grow warm (though the rearmost end will usually stay cold. Like the gas torch, there is no air mixing before the nozzle, and since the final exit pressure is quite low, you get a big orange flame reaching up to a few metres. Because it's a gas (not liquid or gel) fuel, the flame curves upward towards the end due to the hot gases rising. While the can remains engaged with the valve fully open, the pressure in the tube should prevent air from getting in, and thus avoiding blowback, HOWEVER some gas will escape at the interface and work its way at more leisurely pace towards the nozzle. If enough lingers between the plume and the interface you could face an external blowback which would be very dangerous given the can still being open. Now in principle, the urban myth of the "flame returning inside the can" and making it explode seems pretty unlikely given the valve pressure, but it's just not nice to see open flame near a can of pressurised gas open full bore. So keep it to short bursts, 3 seconds is about long enough for me, and I always waited for the internal blowback then let the air clear for a bit before a second blast. A lot of the heat travels upward so don't use this inside or you may cook your ceiling.
Using the gas torch (above - not the flame thrower!) or one of those gas jet cigar lighters or gas powered soldering torches you can melt down lead completely to liquid. This is of course extremely dangerous, because liquid lead is very hot, very runny, and surprisingly heavy (well, it is lead after all). Acquire or make a melting pan. I made pans with a 'valley' shape so that liquid ran to the centre, with the groove extending to one edge for pouring. Lead oxidises quite quickly, and this layer of lead oxide will form a skin on top of your liquid lead, and screw up your sculptures. Put the solid lead on one of the sides of the valley. Apply heat until the lead melts. You may need to give the pan a gentle shake or the lead a poke so that the liquid can burst through the oxide skin and run into the valley. If the lead moves in the pan then it is likely to refreeze if the new area isn't hot enough, so keep the centre of the valley hot. When you want to pour, you need the whole route along the groove to be kept as hot as possible, whilst keeping the lead hot enough to remain liquid. If you have two burners, you can set up a vertical freestanding one under the pan to keep the lead liquid, and use another to heat the groove and spout.
You can pour the lead into various things - clay moulds work to a degree, I found pouring into a container of solid wax was good for making interesting blob shapes. I never got round to trying pouring lead straight into water, so I can't advise, other than to suggest you take care, since the container could well explode from the sudden boiling of the water. Certainly the lead would melt a lot of wax on contact. Keeping a water bath nearby is helpful to cool equipment and creations quickly, but it can spoil the finish of the sculptures. Lead polishes up well, and you can get nice photos of shiny artwork before it tarnishes. Remember of course that lead is also poisonous, and sitting in an unventilated room melting lead is probably not a very good idea. Also, be warned that lead melting equipment can look to the untrained eye like drugs parephenalia - my mother kept confiscating my kits forcing me to make new stuff, until she confronted me about my problem. Hehe. She was relieved it wasn't drugs, but probably not completely satisfied with the situation.
As I said, melting lead is extremely dangerous. If you do get molten lead on your skin it's going to make a mess. However, I always had in the back of my mind the following rule: If something goes wrong, ignore the pain until all the flames are out and all the fuels are away from the hot stuff. Then feel free to thrash about, or better, seek medical attention. You do not want to get everyone thinking about hospitals while your house catches fire. Alternatively, just don't do this, it's bloody stupid.
If you upturn a can of compressed gas with a standard pressure valve (as we've been discussing above), and very slightly depress the valve, then you will get a slow trickle of cold liquid from the tube. This is the gas in liquid form, as it is inside the can. In small quantities it will imediately boil back into a gas and disperse. However, if you let it fall into a plastic cup, the plastic will insulate the liquid sufficiently to allow you to accumulate a decent quantity. This liquid will happily hang about for a little while, allowing you to do all kinds of cool things. For example, if you pour it on paper, the paper will become wet, but only for a few seconds - the liquid will boil away rapidly, leaving surprisingly bone dry paper. (It seems surprising, but it makes perfect sense if you think about it). You can also drop things in it, such as pieces of cake, which then go quite hard, if left immersed for a decent period. If you put your fingers in it, then the skin will go all hard. Just be careful not to give yourself freeze burns. Do NOT drink the stuff. It will mess you up badly. Since the liquid has a much smaller volume than the gas form, you can create 'cold explosives'. Just seal the stuff up in a weak, airtight container, and perhaps apply some external heat. If the heat source is a naked flame, then make sure you are not around to get caught in the blast, because the escaping gas will ignite - instantly boiling the remaining liquid, which will expand to many times its volume, whilst burning, creating even larger volumes of hot product gases, at high velocity, which is what we colloquially call an explosion. Obviously, igniting the gas in liquid form is a very poor idea, for reasons just described. In short, cans of butane lighter refill are a great way to gain easy access to some fascinating domestic physics. Just make sure you are able to control the experimental environment, or you may receive some unfortunate lessons in hazard control.
You know those strings of firecrackers like lots of little sticks of dynamite attached to a big central fuse? Well split off a few of those, get a short log about the width of an arm, or perhaps make a mockup musket shape out of offcut wood. Drill a hole into the muzzle end, just wider than an individual firecracker, and a bit deeper than the length. Get a slow fuse (that rope stuff that smoulders flamelessly, that you use for lighting fireworks), and light the end. Put a firecracker in the hole in your musket with the fuse just poking out, ignite the latter with the rope fuse, aim and wait. When it goes off, it looks and sounds like an english civil war musket! If you fancy a challenge it's possible to turn it into a real (though crappy) musket, but it's a lot of work, and the results aren't really worth it. Anyway, it's more fun to play with fake ones, because, well, you can't accidentally kill your friends.
I had so many projects that I never really got beyond design stage, due to an unfortunate period of "growing up". Maybe one day I'll get round to building the ACME Handgrenade - an old tennis ball filled with retasked model rocketry black powder, painted black, with a length of handheld-sparkler stuck in the top and BOMB painted on it in white. So cool! Or the fuel-air tennis ball bazooka. Or the thermite mine. Sigh...