Fire piston

Hmm, is so fun to play with this device known as fire piston. However you need a great strength to push the piston in order for the cotton wool (or any combustible material) to ignite. Above is the video of fire piston.

A fire piston is a device of ancient origin which is used to kindle fire. It consists of a hollow cylinder ranged in size from around 7.5 cm to 15 cm long, sealed at one end and open at the other. A piston which is about 1-2cm in diameter, can slide into the cylinder forming an airtight seal with the cylinder wall. The piston has a handle on the end to allow a firm grip to be applied to it and can be completely withdrawn from the cylinder.

The piston must be rammed quickly into the sealed cylinder with a single stroke. The compression of the air causes the temperature to rise rapidly to 260 degrees Celsius. This is hot enough for the cotton wool inside the piston to ignite. It can then be withdrawn and transferred to a larger mass of kindling to create a fire.

The principle of fire piston works based on rapid compression of the air (known as adiabatic compression) increases its pressure and its temperature at the same time. If this compression is done too slowly the heat will leak away to the surroundings as the gas returns to equilibrium with them. If the compression is done quickly enough then there is no time for equilibrium to be achieved and the absolute temperature of the air can suddenly become several times that of its surroundings, increasing the original room temperature of the air to a temperature hot enough to set the cotton wool alight. The air in the cylinder acts both as a source of heat and an oxidizer for the cotton wool.

Making glue from milk

Running out of glue? You can make it yourself. Ha Ha but I have tried it, is quite time consuming even though it looks easy. So is better to go and buy one. But one thing I need to comment about this glue is that you see it like normal flour with water. But its strength is amazing once you stick it and it dries. I tried to stick metal, glass, wood and all of them stick well. I even tried to pull them apart with strength. But maybe glass and metal have smooth surface so I am able to separate them. However the wood is stick so tightly that I cannot pull the 2 wooden block apart.

So just want to share this receipe, when you REALLY free then you can make the glue yourself. Do not worry about ants or what even though milk powder is used, it is because I think the acid and base have made it so unpleasant that it will not attract ants.

This is how I do it -

1) Dissolve 10g of milk powder in 50ml of warm water

2) Add vinegar or 1M HCl dropwise until the milk separates into curds (white solid) and whey (yellowish liquid)

3) Use a cheese cloth to add as a sieve to separate the curds from the whey.

4) Wash the cheese cloth with the curds inside to remove the acid.

5) These curds is also known as casein and it is then dried on filter paper (as shown).

6) Place the dried casein in a beaker and add 20% sodium hydroxide dropwise and stirred to make it into a homogeneous paste.

7) Finally add 1.5g of calcium hydroxide powder and stirred until a thick creamy liquid is form and this will be the glue.

I tried to leave it for a few days in a covered container and it does not dried up even it is dried just add a drop of water and stir the glue can be used again. Another good thing is that it do not have any glue smell so it is quite safe.

So hope you like my receipe if you are currently unsatisfied with your glue. Try to make one yourself.