[paul.fr]

What about writing a letter saying that you are being black=mailed by the victim and you think you have found a way to stop it. (In other words MURDER THEM!!!)
If you write with an ink pen you can do chromatography on a sample of ink that came from the letter and different types of ink that came from the suspects pens. They have to find out who's pen wrote the letter.

Yes, but first you will need to tell us how to do it. In the meantime, we need to get some fingerprints from that glass we suspect had poison in it.

What you need


Large ziplock bag
Tube of superglue
Drinking glass


What you do



Place the glass into the bag. Make sure you touch the surface using the pads of your fingers, leaving a nice smudge free print.
Lay the bag flat on a counter or work surface and squeeze a few drops of glue into the bag. Do not glue the glass to the bag, now seal the bag tightly and wait a day or so for the prints to develop. You can speed the process  time up by introducing a lamp near the bag, the heat from the lamp should quicken the process.

Explanation
The vapours from the superglue will build up in the bag and crystallize on the fingerprints. A day later, you will see starchy white fingerprints on the surface of the glass.

[keydetpiper]

What you need
A good-natured and relatively flexible friend
A wall

What you do
Have your friend bend over and touch his toes (or try at least). No problem! Now ask him to stand with his back and heels against the wall and bend over to touch his toes. Can't do it, no matter how strong or flexible!

What happens
Barely noticeable when someone does it in a room, bending over requires a slight backward shift of the hips. The moves the body's center of mass above the feet, and if the center of mass is above the feet your friend stays upright. With the wall, your friend can't shift his hips backwards, so the center of mass can't move to be over the feet. The result is a rather rather clumsy looking friend.

A variation is to have your friend stand sideways with his right shoulder and right foot against the wall, the tell him to pick up his left foot (the one away from the wall).

[DoctorBeaver]

Alka-Seltzer rocket
You will need:-
Empty film canisters or similar
Alka-Seltzer tablets
Teaspoon
Water

Method:-
Remove the canister lid and put 2-3 teaspoons of water into the empty canister
Break off a quarter of an Alka-Seltzer tablet and put it in the lid
Tip the quarter tablet into the canister and shut the lid tightly
Shake the canister for a few seconds and place it lid-down on a flat surface
Stand well back for this one!

If you are a minor, please make sure an adult is present and get permission from your parent or guardian before beginning this experiment.

[Make it Lady]

You can also use a fizzy drink as fuel of vinegar and bi-carbonate of soda. The latter launches quicker so you have to be very quick.
Note: The film canister must have an internal seal or it won't work.

[DoctorBeaver]

You can also use a fizzy drink as fuel of vinegar and bi-carbonate of soda. The latter launches quicker so you have to be very quick.
Note: The film canister must have an internal seal or it won't work.

I tried it earlier with an aspirin bottle (a plastic 1) and it worked.  [B)]

[daveshorts]

Lemon juice is generally slightly less violent than vinegar, but it still has a tendency to blow up in your face if you overegg it

[paul.fr]

I tried it earlier with an aspirin bottle (a plastic 1) and it worked.  [B)]

We used to do this in shopping centres, back in they day when all you got was a clip round the ear from a "friendly" policeman. I reckon you could get locked up now.

[paul.fr]

Whilst we wait for Sharon to tell us how to determine which pen was used on the blackmail letter, we best start lifting some fingerprints.

What you need


Fingers
Friends
An assortment of drinking glasses
Cocoa powder
A small artists brush
A magnifying glass
Inkpad
White paper, one sheet per person


What you do

Give everybody a glass and a sheet of paper, make sure the glass is clean and has no marks on it. Everybody needs to make a finger or thumb mark on the rim of the glass.

Once this is done, swap glasses (being careful to touch only the base of the glass. Don't smudge the prints that are already there.) Using the brush, place a small amount of cocoa powder over where the prints were  made. lightly dust over the prints to help make them a bit clearer.

On sheets of paper get each person who left a print originally to make another print - but this time they have to press their finger or thumb in the inkpad first.

Match these new prints to the ones you dusted for earlier. Use the magnifying glass to help you inspect them even more closely and try to match them up.

Who left which prints? Who wrote the blackmail letter?


Explenation

No two fingerprints are the same, even twins will have differences in their prints.

When you examine a print you'll notice the lines occur in one of three characteristic patterns, known in the biz as 'arches'. 'loops' and 'whorls'.

When you come to compare the chocolate and the ink prints you should get an exact match between pairs. But although two different people may have the same fingerprint type (eg. both have loops on the same finger), there will always be other little differences between individuals. That's because it's not the shape of the print that’s unique, but rather the number, location and shape of specific ridge characteristics...

What you were lifting with the cocoa powder are called 'latent' prints. These prints are formed by oil and sweat from a person's fingers when they touch a surface - the sweatier you are the clearer they’ll be (so remember to wash after being sweaty)! They're invisible to the naked eye, which is why they need some kind of treatment to help you see them.

Topic link/s
What causes "fingerprints", and why do we all have different ones?
Fingerprints
How Identical are identical twins ?

[paul.fr]

What you need


 Red food colouring or joke / stage blood
 Dropper
 Small beaker
 Plain Paper
 Ruler
 Metre rule / tape measure



what you do



Lay out some paper to protect the floor, then place the paper you?ll drop the blood onto on top of them. Hold the dropper 10 cm above a clean sheet of and drip one drop of blood onto the sheet., now measure the distance of the spatter, making sure to write down the height it was dropped from and the diameter of the splatter.

Drop the blood from 20cm higher each time until you get to 200cm or higher if you wish (you can go up in larger or smaller amounts depending on how much time you have). Measure the diameter of the spot and write it down as well as the height it was dropped from.

Use a new piece of paper to drop the blood on every time you change height (this will avoid confusing results), and make sure you?re measuring the distance of the splatter each time you drop the blood.

Once you?ve done this, get someone else to do a splatter at a distance of their choosing (it can be any height within the range of the distances already dropped i.e. 10cm to 200cm). Make sure whoever conducted the test originally can?t see the random drop, because their task now is to work out what height it was dropped from by measuring its splatter and comparing it to their results from before.

If they have recorded their results accurately, then they should be able to make an 'educated' guess what height the random drop was dropped from.


what happens?

This type of forensic analysis is called Bloodstain Pattern Interpretation, or Blood Splatter. What we?re trying to do is re-create the circumstances in which a crime may have been committed.

Once you know about the different ways that blood splatters, and can recognise certain signs, you can begin to work out what happened. It does require some specialist training though.

The specialist will try to determine what the position and shape of the spatter indicate. They take measurements to determine the trajectory as well as carrying out carefully controlled experiments.

These experiments will use materials very similar to those found at the scene, because blood reacts differently depending what surfaces are involved. For example it will behave one way when it hits a carpet, and another when it hits a tiled floor. Using the results of the experiments, investigators can try to reproduce what has happened.


explenation

 Shedding of blood is the dramatic accompaniment to murder committed by violent means. Blood accounts for about 9 per cent of a healthy person's body-weight and as many murderers have discovered to their cost, when it is spilled a little goes a long way.  Once blood is shed in any quantity, and especially when it starts to clot, it becomes very difficult to deal with. Murderers' attempts to clean up after their violent handiwork often fail because of blood-traces which adhere tenaciously to their clothing or to the murder weapon. Blood found at the scene of the crime has trapped many killers who thought they removed all incriminating traces. A sensational demonstration of this was provided by the French detective Gustave Mace in 1869, when he was interrogating a murder suspect in the room which he believed had been the scene of a ghastly crime involving the dismemberment of the victim. Convinced that a great deal of blood must have been shed, Mace looked about the room but could see no obvious traces.  Then he noticed a marked hollow in the tiled floor. With the suspect looking on in astonishment, the detective took a jug of water and tipped the contents on the floor - the water collected in the hollow area, and when the tiles were lifted their under-surfaces were found to be caked with dried blood. This discovery led to a murder confession by Pierre Voirbo and to a triumph of detection for Mace.

Blood is important forensically, and can yield a great deal of information to the investigator. The first task in examining suspicious stains is to determine whether they are blood, and if so, are they human? Once this is established stains are examined for age, sex and blood group. The shape and pattern of liquid blood-splashes can help in reconstructing the murder; bloody fingerprints and palm-prints tell their own story; dried blood on a suspect's clothing can be related to the victim, the crime scene and the murder weapon; blood and tissue forced under the fingernails of the victim during a violent struggle can be linked to the assailant.

Thus a single blood-trace can provide a wealth of information, and analytical techniques are improving all the time. Blood dynamics is important not only for narrowing suspicion on the guilty but also in showing a suspect's innocence. As in many other aspects of forensic investigation, bloodstains are taken into account with a variety of other evidence to build up a pattern of crime.

The investigation of blood at a crime scene can be broadly divided into a biological approach (serology) and a physics approach (blood splatter or bloodstain pattern analysis). This fact file will concentrate on the dynamics of blood evidence.

Examination and interpretation of bloodstains on and around the body, and of blood-spots, splashes and smears at the scene of the crime, are an essential part of a murder investigation. The position and appearance of blood marks on the body and its immediate surroundings will help the investigator to reconstruct the crime.

The theory behind bloodstain pattern analysis is simple: blood is a fluid and will respond accordingly to the laws of physics. Though rarely the dominant piece of evidence in an investigation, bloodstain pattern analysis can be important in the difficult process of reconstructing a violent crime.

Experts begin by taking note of a few key variables:

    * spot size
    * quantity
    * shape
    * distribution
    * location
    * angle of impact
    * target surface

A great deal can be gleaned from the shape of blood spots and splashes found on surfaces such as floor, walls, ceiling, woodwork and furniture. The French criminologist Alexandre Lacassagne noted the correlation between the shape of blood sports and the position of the victim. Blood dropping vertically on to a flat surface form a circular mark with crenated edges, and denotes that the source was stationary at the time. Drops of blood falling from a moving object hit a flat surface obliquely and leave a spot shaped like an exclamation mark. An examination of the shape of obliquely falling blood splashes yields information about the direction and speed of impact. Such evidence helps determine the positions of victim and murderer at the time of an assault, and may also indicate the manner of violence and type of weapon used.

A line of blood spots on the ceiling of a room in which violent murder has been committed is likely to have been made by the killer wielding an axe or bludgeon in an area over his head. Smears and trails on the floor may be produced by a wounded person crawling about or by an assailant dragging the body of his injured victim. Smudges and smears on furniture and doorsteps leaving bloody fingerprints or palm prints may result from similar activities. Blood smears tend to start as drops which become ragged at one edge, indicating the direction of travel.

Large spots - the blood was travelling at a relatively low velocity.
   

Small spots - the blood was travelling at a relatively high velocity. (More force equals smaller splatter)
   

Elongated drops - victim was moving, their speed relative to the amount the spots are stretched and how far they are spaced apart. (Also indicates directionality)
   

Contact - large stain on a surface caused by contact with a bloody object.

Void in otherwise uniform splatter - something blocked the blood spray.
   

Cast-off - straight, elongated lines of splatter indicating that blood was thrown by a moving object in a change of direction. (Can show how many times a victim was struck)


Even when the blood stain is not evident it may still leave a tell tail fingerprint. To detect invisible blood stains, the luminol test is used, which is a chemical sprayed on carpets and furniture which reveals a slight phosphorescent light in the dark where bloodstains (and certain other stains) are present.

What is the luminol test?

The specialist will try to determine what the position and shape of bloodstains at the crime scene indicate. He/she take measurements to determine the trajectory as well as execute carefully controlled experiments. These experiments will use surface materials like those found at the scene to try to reproduce what has happened.

A leading authority on blood stain interpretation gives the following tips to investigators:

    * It is possible to determine the impact angle of blood on a flat surface by measuring the degree of circular distortion of the stain. In other words, the shape of the stain tends to change depending upon the angle of impact which caused the stain. For example, the more the angle decreases, the more the stain is less circular and more long.
    * Surface texture is one of the key components in determining spatter type. The harder the surface is, the less spatter will result. It is therefore extremely important to duplicate the surface in a controlled test.
    * When a droplet of blood hits a surface which is hard as well as smooth, the blood usually breaks apart upon impact. This in turn causes smaller droplets. The smaller droplets will continue to move in the same direction as the original droplet.

One of the classic murder cases in which blood evidence played an important, if controversial part was the trial of Dr Sam Sheppard. The doctor's wife was found dead in their Cleveland Ohio, home in July 1954. Her body, with the head brutally battered by over thirty blows from a heavy object was found in the master bedroom. The room, which had been ransacked, was heavily spattered with blood, and a trail of stains led down the stairs and out on to a terrace.

Dr Sheppard, who had been awakened from sleep on the living room sofa by his wife's screams, claimed to have been knocked unconscious by an intruder as he rushed upstairs. His behaviour was judged to have been suspicious, and there was considerable prejudice against him, not least on account of his alleged infidelity. He was sent for trial and found guilty of second degree murder, for which he was sentenced to life imprisonment. The coroner had made much of bloodstains on the pillow in the murder room, and a bloody imprint which he suggested had been caused by a surgical instrument which had served as the murder weapon. This instrument was never specified, but the imputation was plain that Sheppard, himself a doctor, had used it to murder his wife. The murder room abounded in blood evidence which if properly examined would have led to other conclusions. It was left to Dr Paul Leland Kirk, Professor of Criminalistics at Berkeley, to make a thorough assessment of this evidence several months later in order to reconstruct the murder. As the bedroom ceiling showed no traces of blood, Kirk reasoned that the murder weapon had been wielded in a more or less horizontal fashion. This was borne out by the state of blood splashes on the walls, some of which had been flung from the murder weapon as it was swung backward and forward to make contact with the victim's head. Other blood spatters had come directly from the battered head. The Professor carried out experiments which suggested the most likely weapon to have caused the pattern of blood splashes was a heavy flashlight. He also judged that the murderer stood between the twin beds, having noted blood drops which had been smeared into streaks on the right side of the victim's bed. This interpretation was supported by blood free areas on two of the walls behind the murderer which had been protected from flying blood spatters by his body. A killer standing in that position must have swung the murder weapon with his left hand - Dr Sheppard was neither left-handed nor ambidextrous.

By implication, the murderer must have been thoroughly spattered with blood. Yet apart from a bloodstain on the knee of Sheppard's trousers, which got there when he stood close to the bed to take his wife's pulse, there was no evidence of other blood staining on his clothes A number of factors similarly pointed away from Dr Sheppard as the murderer - it was certainly the case that the examination of the blood evidence had been bungled in the first instance. There was no better illustration of this than the admission during a second trial that the trail of stains leading from the bedroom through the living room and out on the terrace had not even been properly tested for human origin, nor was blood groupings attempted. Professor Kirk's interpretation of the blood evidence went a long way towards securing Dr Sheppard's eventual freedom.

Film and television aficionados may recognise the recognise in this case the opening premise of The Fugitive. Obviously the series would have been a lot shorter with the help of a good bloodstain expert.

Some common terms used in bloodstain pattern interpretation.

    * Angle of Impact  --  The acute angle formed between the direction of a blood drop and the plane of the surface it strikes.
    * Cast-Off Pattern  --  A bloodstain pattern created when blood is released or thrown from a blood-bearing object in motion.
    * Drip Pattern  -- A bloodstain pattern which results from blood dripping into blood.
    * Flight Path --  The path of the blood drop, as it moves through space, from the impact site to the target.
    * Flow Pattern  --  A change in the shape and direction of a bloodstain due to the influence of gravity or movement of the object.
    * Impact Pattern  --   Bloodstain pattern created when blood receives a blow or force resulting in the random dispersion of smaller drips of blood.
    * Misting  --  Blood which has been reduced to a fine spray, as a result of the energy or force applied to it.
    * Projected Blood Pattern  --  A bloodstain pattern that is produced by blood released under pressure as opposed to an impact, such as arterial spurting.
    * Spatter  --  That blood which has been dispersed as a result of force applied to a source of blood.  Patterns produced are often characteristic of the nature of the forces which created them.
    * Target  --  A surface upon which blood has been deposited.
    * Transfer/Contact Pattern  --  A bloodstain pattern created when a wet, bloody surface comes in contact with a second surface.  A recognizable image of all or portion of the original surface may be observed in the pattern.
    * Wipe Pattern  -- A bloodstain pattern created when an object moves through an existing stain, removing and/or altering its appearance.

Forensic Serology

[paul.fr]

What you need

a drinking glass
ice


what you do


Outside on a cold day you often see your breath turn into a white mist that looks somewhat like a cloud, but why? and can we duplicate this effect?

Take a short glass or plastic cup and put ice in it, filling it no more than halfway, then gently blow across the top of the glass or even slightly down into it until you see your breath making a white mist. If you are unable to see a white mist sprinkle some rock or table salt into the ice, mix it up a little and and then try blowing across the top of the glass again.

explanation
This happens because your breath is warm and it can hold more water vapor than the cold air outside. Some of the water vapor in your breath quickly condenses out into tiny water droplets that you can see.
topic link/s

[paul.fr]

The Coriolis effect has been discussed recently on the forum, but what is it and can we visualise it's effect with just a piece of paper, a pencil and a few spare seconds?

What you need


A piece of paper, say A4
A pencil


What you do


Steadily, and carefully, rotate the piece of paper clock or anticlockwise with one hand, and attempt to draw a straight line from one edge of paper to the centre. You may want to mark the centre of your rotation with a small circle to begin with, this will represent one of the poles.


What happens?


Explanation
To begin with, we should know what the wind is and what causes it. The ultimate cause of Earth's winds is solar energy. When sunlight strikes Earth's surface, it heats that surface differently. Surfaces such as snow, sand and soil absorb different amounts of heat. This creates uneven heating of the earths surface, this leads to a difference in air pressure.


As a result we have differences in air pressure (and heat)over the earth, high and low pressure. Very simply, At the equator hot air rises and moves out towards the poles, gradually cooling. It eventually sinks back down to the earth's surface. This cooler air is then forced to flow back to the equator to replace the hot air that is rising. This is wind.

The Coriolis force results in a deflection of air to the right of the direction of the pressure gradient force

Watch this video

Wind Circulation

understanding coriolis

pressure gradient force

[Bass]

PANNING FOR GOLD

For anyone interested in panning for heavy minerals (gold, platinum, metallic minerals, iron minerals, and others including rubies, sapphires and garnets)- here is a brief "How to" guide.  Takes a little time and effort.

What you need

gold pan (I recommend green plastic pans with built in riffles)
shovel
waterproof boots and gloves
small jar (to store all the nuggets!)
small magnet wrapped in Saran Wrap

In streambeds, try to dig down to bedrock if possible, or get as deep as possible.  Also look for areas of slack current, such as on the lee sides of boulders.  For beach sands, try to either collect sand that is on bedrock, or find places in the sand where heavy minerals (magnetite, limonite, hematite, illmenite, zircon) collect (a magnet wrapped in Saran Wrap will help you find magnetite if any exists). 

Best to fill the pan about 3/4 full, then in calm water, work the sand/gravel with your hands until you get rid of all the mud/silt (fill the pan with water, work the sediment until muddy, then pour off the muddy water- continue until water stays somewhat clear when stirred up).  The green platic gold pans with riffles built in make this much easier.

Fill with water, then rock the pan gently back and forth while slowly swirling it in a circular motion (this is to get the heavy material to sink to the bottom).  After you've agitated the pan enough to get the heavies to sink, slightly tilt the pan and allow the water with the top layer of light material to wash out.  You can dip the tilted pan into the water several times to allow the top material to wash out.  Fill with water again, swirl and rock the pan, flush out the top layer.  Repeat this until only a small amount of material remains in the bottom of the pan (often this will be mostly black).  You can pick out any obvious non-mineralized pieces of gravel, as these will also sink to the bottom since they are heavier than the sand.  Gently swirl the pan letting the heavy material in the bottom move a few mm at a time, then use a magnifying glass and see if a thin gold line exists at the back (the gold will not move much since it is heavier).  You can remove magnetite (most common black sand residue) with a magnet wrapped in food wrap.

With practice, you can do this in a few minutes- first timers generally take 15-25 minutes.  This is much more enjoyable when the air and water temperatures are warm, otherwise wearing waterproof gloves really helps.

Good luck and have fun!

[paul.fr]

What you need


Cotton Wool balls
Pippet or eye dropper
Glass of water


What you do

hold the cotton ball in one hand and the eyedropper in the other. The best way to hold the cotton wool ball is to hold a small portion of the cotton ball between the thumb and index finger.

With the pippet put as many drops of water into the cotton ball as possible. The cotton ball will be full (saturated) when water begins to drip from the bottom. How many drops of water do you think it will take for the cotton wool ball to become saturated?


Explanation

Since no two cotton wool balls are the same, and the drops will all be different, this is what is happening in nature and the formation of clouds. The cotton wool ball represents a white fluffy cumulus cloud.

One inch of rain over one square mile equals 17.4 million gallons of water weighing 143 million pounds (about 72,000 tons). The 'average' cumulus cloud is made up of over 10,000,000,000,000 drops and weighs about 2 billion pounds!

[neilep]

What You Need:

Two balloons
A Funnel
Water
A Candle
A grown up (if you are a youngie)


What you Do !

Blow one balloon up , secure it and move the candle towards it....it POPS !!!

Fill the second balloon with just a small amount of water..half a cup lets say.
Blow the balloon up...secure it.

Light the candle and slowly move the candle towards the balloon placing the flame where the water is.

What happens ?..or what does not happen ?




Explanation

Don't let the flame heat the bottom of the balloon indefinitely as it WILL burst....but...you should be able to have the flame beneath the balloon for a while. Even to the point where the rubber is gaining a lot of soot from the candle.

Just as the rubber reaches popping temperature , the water inside absorbs the heat and stops it from popping.

[paul.fr]

What you need:

Two empty drinks cans
A level surface


What you do:


Lay the two cans parallel to each other, about one inch apart, near the edge of a level surface. Get down to the level of the floor/surface and blow between the two cans.

What happens?

It may take some practice, but the two cans will roll together.

Explanation:

The affect is Bernoulli's principle in action, named after the Dutch/Swiss mathematician/scientist Daniel Bernoulli. By blowing between the two cans, you are making the air between them move faster than the surrounding air. The cans roll together as the higher pressure surrounding the two cans pushes the cans together toward the region of lower pressure.

[paul.fr]

What you need


Two, empty two litre bottles (plastic)
hot tap water


What you do


Put two or three cups of hot tap water into each of the bottles, then put your thumb over each bottle opening and shake for about thirty seconds to a minute.

Pour the water out of each bottle and screw the bottle lid on one of the two bottles. Place the two side by side an observe for about 10 minutes.


What happens?


The bottle that had the lid screwed on Should have collapse, yet the other bottle should remain unchanged.


Explanation

The bottle collapsed due to the air cooling inside that bottle. The air cools because the molecules and atoms inside the bottle loose energy as they collide with the bottle side that is exposed to the cooler surrounding air. As their energy decrease so does their velocity and therefore the pressure decreases. Since the pressure inside the bottle decreases, the force of the air outside the bottle begins to crush the bottle.

However the uncapped bottle remains unchanged. As the air cools inside, the drier outside air flows in to take up the space thereby keeping the pressure the same both inside and outside of the bottle.

[paul.fr]

What you need


Two table tennis balls / ping pong balls
Hair drier


What you do


Point the nozzle of the hair drier upwards and turn it on to full power, it can be blowing cool air as there is no need for heat. Place one of the balls into the stream of air, and then carefully add the second.


What happens?

Both balls should be suspended by the air, they will occasionally collide with each other making a clicking sound.


Explanation:

Had the balls been raindrops, every time they collided, they would have joined each other, making a larger drop of water.

In rising (cooling) air, water vapor begins to condense on cloud condensation nuclei when the air has cooled to the dew point temperature. As the air continues to rise and cool, water vapor will eventually condense onto the cloud condensation nuclei and form cloud droplets. Since there are many sizes of cloud condensation nuclei in any given air parcel, the cloud droplets that form will be different sizes as well.

As a result of the cloud condensation nuclei size distribution, some cloud droplets will be larger than the rest. Eventually, the largest cloud droplets begin to fall faster than the smaller droplets because large drops have faster terminal velocity than small drops. As these large cloud droplets fall, they collide with the small cloud droplets.

Many times, these droplets will stick together and become one large drop (coalesce). Eventually these droplets fall from the cloud as raindrops, reaching a diameter of approximately 10 mm (0.39 inches). After a raindrop reaches 10 mm, it becomes so large that it breaks up into smaller drops.

[paul.fr]

What you need


A freezer
A piece / block of polystyrene


What you do


Pop the polystyrene in to the freezer and leave for 24 hours, take it out.
What has happened?

You should notice that the polystyrene is not frozen and in fact feels warm to the touch!

Explanation:

Hay, don't look at me for an explanation!
Lets throw it open to the forum members.

Link:
Why does polystyrene not freeze?

[Bass]

COSMIC RAY CLOUD CHAMBER

What you need

Wide-mouth Canning jar (1 pint or 450ml size works well)
Metal pan
Felt cloth
glue or double stick tape
pure isopropyl alcohol
dry ice
flashlight

What you do

Cut the felt cloth in a circular shape to fit jar lid
Attach felt cloth to the inside of the jar lid (don't cover the rubber seal)
Pour a small amount of alcohol into the jar (enough to thoroughly wet the cloth plus a little extra)
Seal the jar (a tight seal is necessary)
Place the jar upside down on top of dry ice in the pan
          Remember to wear gloves when handling dry ice

What happens

Due to the temperature difference (warm jar and cold lid), the alcohol will begin to condense and form an alcohol "fog"
As cosmic ray particles travel through the jar, they will ionize particles along their path, causing intense condensation (look for streaks like contrails from jets)
Shining the light at different angles may illuminate the cosmic ray streaks better
Only a thin layer of "fog" will form just above the lid with felt cloth at the bottom.

[paul.fr]

Excellent, as usual Bass