These experiments require adult supervision and/or assistance as they deal with cooking and/or chemicals that require special handling.

Magical Disappearing and Reappearing Invisible Ink

This is from the Book Chemically Active! by Vicki Cobb

You will need:
1 Tablespoon starch solution (see below)
3 clear glasses
1/2 cup 3% hydrogen peroxide (found at pharmacies or dollar stores)
1/2 cup water
1 Tablespoon white vinegar
a few drops of iodine (most pharmacies carry this)
1 or 2 drops of hypo solution (dissolve 1 teaspoon hypo crystals in 1 Tablespoon water)
a wand

To make the starch solution, mix 1 teaspoon of cornstarch into 1 cup of water. Heat and stir until the cornstarch is completely dissolved. Add another cup of water. This can be stored in the refrigerator for a couple of days. Be sure to give it a good shake before measuring out your tablespoon for the experiment.

Put the starch solution, peroxide, water and vinegar into one glass. It will look like water. Put a few drops of iodine in the bottom of one of the other glasses, and 1 or 2 drops of hypo solution in the bottom of the third glass.

Pour the invisible ink into the first glass. The iodine will react with the starch to give the blue-black colour that is a test for starch. Now pour it from there into the third glass. The hypo will form a colourless compound with the iodine which frees the starch (which is also colourless) so the liquid goes clear again.

While this is happening, the hydrogen peroxide is also breaking down and adding oxygen to the mixture. The oxygen makes a more permanent compound with the hypo than the iodine, so the hypo leaves the iodine which becomes free again to react with the starch. So after about 15 seconds, the liquid turns blue-black again.

If you dip the end of your wand into the hypo solution and use it to stir the liquid, it will go clear again until the oxygen combines with the extra hypo.

Hypo is the photofinishing chemical sodium thiosulphate. I was able to talk the owner of a photography store into selling me a small baggie; otherwise you need to order it from a chemical distributor in huge quantities. It can be disposed of down the sink or toilet, and as long as you don't ingest it, it is safe for use. If you are unsure, please ask for a WHMIS safety data sheet when you buy the hypo.

Dry Ice Experiments

Dry ice, which is really frozen carbon dioxide (the stuff we exhale, and also a major greenhouse gas), sublimates at room temperature. That means that when it hits the heat of the room, it changes directly from a solid into a gas. This gas is heavier than air, so if you are working with dry ice, don't leave any small children or pets at floor level as they may not get enough air. Be sure to keep your room ventilated. It is not toxic to breathe, but it isn't air either!

Be sure to handle it properly, as dry ice will burn skin. Heavy leather or non-synthetic gloves and safety goggles are strongly recommended. If in doubt, ask your supplier for safety information.
Dry ice is available at many party suppliers and also through medical supply companies.

When dry ice sublimates, it makes a foggy trail across the floor. This is often used to create fog and smoke effects in the theatre and also at Halloween. When it warms and sublimates, it also expands. The following experiments take advantage of these properties to make some pretty cool effects.

Dementor Breath Bubbles

For this you will need:
dry ice pellets
a plastic bottle
warm water
liquid dish detergent
a small piece of sponge that fits just snugly enough inside the mouth of the bottle that it won't fall inside
optional: a piece of flexible tubing that fits on the top of your bottle

Soak your sponge in the water and squeeze it out, then dribble dish detergent on it so it becomes not quite saturated.

Pour a small amount of warm water into the bottle, then add a few dry ice pellets. Plug the top loosely with the sponge. As the gas expands, it will be forced out through the soapy sponge and make misty bubbles. For variety, attach the tubing to the mouth of the bottle so that the bubbles can "fall" down off the end of the tube. You can also just fill a bowl with soapy water, then add some dry ice pellets and watch the bubbles foam. It will make a bubbling potion sound as the bobbles form and burst.

More Fun with Dry Ice (aka frozen Dementor's breath)

Try and make a spoon scream by first running it under hot water, then pressing it against a dry ice pellet. You can also use various coins and other metal objects. Experiment to find out which ones make higher and lower notes.

We made dry ice ice cream. The main trick to this is to use a very large bowl, as it will increase dramatically in volume (~4 times the volume at the very least). It also gets very misty. We used the ice cream recipe on the edible concoctions page, and added dry ice right into it. This requires continuous stirring until the mixture thickens. It is best to pop it into the freezer for a while before eating to be sure that all the dry ice has sublimated before eating. You can monitor this by putting a few pellets into a container beside the ice cream in the freezer. When they disappear, the ice cream is ready.

You can also make rockets with dry ice. Be sure to only use containers that do not seal (no plastic or other bottles with lids). A film cannister with a pop-off lid works well. The dry ice rocket will work like the baking soda rocket, the only difference being the fuel you use. Since the container is quite small, you will need to use a small chunk of dry ice. To break dry ice, have an adult use heavy leather or other natural fibre gloves and insert larger pieces into a pillowcase. Tie shut. Wearing safety glasses, use a hammer and strike the dry ice in the pillowcase. Remove the smaller pieces with gloved hands.
To fuel your rocket, first read the dry ice warnings and instructions for the baking soda rocket. Build your rocket, then fill the cannister about 1/4 full of warm water and drop in a piece of dry ice, quickly replace the lid and move away from the rocket.

For a dry ice candle extinguisher: Sit a a pellet or two of dry ice in a container for a couple of minutes until it has sublimated (tuned to gas), then pour the container onto a candle flame and watch the flame go out.

Dry ice levitation: Sit a pellet on a smooth firm room-temperature surface and watch as it sublimates. With a gloved hand, use a spoon or other implement to gently push it forward. As the pellet becomes gas, a layer forms all around it and the solid part floats on this layer of gas until the surface cools.

To make a container "burp" fill the bottom of a shallow dish with water. Add a pellet of dry ice and sit a mini plastic yogurt or applesauce container over it. Watch it rise and release gas as the dry ice sublimates. If it doesn't "burp" for a while, check to make sure the water hasn't frozen a seal around the container. Move the container as necessary.

Red Cabbage Water Indicator Rainbow Potion

Ingredients:
red (purple) cabbage
water
stainless steel pot
stove
baking soda
vinegar
powdered laundry detergent
various household liquids and powders (see the warning below)--lemon juice, water, baking powder, sugar, salt, calcium tablets /Tums, dish soap (do not use dishwasher detergent as this is very corrosive and dangerous to handle), hand soap, etc.
pop rocks candy
several small clear containers
a stirring wand or spoon
optional: litmus paper

Prepare the cabbage water by chopping up the red cabbage into tiny chunks. Boil it until the colour of the leaves has faded quite a bit, then strain out the cabbage. Use it for a soup or casserole. Keep the red water; this will be our main ingredient. It can be cooled and refrigerated overnight, or frozen if you won't be using it immediately.

Separate out about 1 tablespoon of cabbage water and add a few drops of vinegar. What happens? Vinegar is an acid. Now try adding a pinch of baking soda. Baking soda is alkaline (a base). What happens?

If you have some litmus paper, you can try testing some liquids and powders (add a little distilled water to the powder). It may help when comparing results to make a chart of the colour obtained from the litmus paper compared with the cabbage water.

*WARNING: some cleaning products can create toxic fumes when combined with other substances. Always read the labels, and never mix chlorine bleach with vinegar, ammonia or other cleaning fluids.

If you would like to mix the substances together, try the following: pour a few spoonfuls of the cabbage water into your container. Add a small spoonful of powdered laundry detergent and stir. Note the change. Add a couple of squirts of vinegar, stir and observe. Add a small spoonful of baking soda and stir. Observe. Add a pinch or two of pop rocks. You may also wish to add yellow raisins and/or gummy worms, although they do not cause much change to the potion.

To use this experiment for a wizard or Halloween party, use names such as: Powdered Root of Asphodel, Ground Bicorn Horn, Pulverized Dragon Eggshells, Leech Juice, Boomslang, Basilisk Venom, Shrivel Figs, Night Crawlers, Yeti Dandruff, etc. for the various ingredients (let your imagination run wild!).

Easy Tie-Dye

Materials:
Commercial dye in at least two colours (more for a rainbow effect)
optional: soda ash (helps the dye take to the fabric)
squirt bottles
water
salt
plastic buckets or dish tubs
elastic bands
optional: a marble
rubber gloves
plastic bag for each dyed item
100% cotton items for dying: try t-shirts, pillowcases, bandanas, tote bags, socks, painter caps, even bed sheets!

About commercial dyes: Rit or Tulip dye kits work well; Rit will give more pastel colours, Tulip brighter, bolder colours; Tuilip kits tend to be more expensive, but a bit more "user-friendly".

This activity is best done outdoors. You may wish to protect your working surface with a plastic sheet. Pre-wash all cotton items to remove sizing; do not use liquid or dryer fabric softener.
Soak your cotton item in water or soda ash and water, then tie as desired. Try twisting and knotting your sections for various effects. Wrap an elastic band around your sections to hold them tightly together.
For a rainbow effect, find the centre of your item and place a marble on the opposite side of the fabric, twist it, then hold it in place by wrapping it with an elastic band. Twist the fabric into a tube from that point downward, fastening an elastic around the tube every 4-8 cm until you run out of fabric.
Prepare your dye according to the manufacturer's instructions, putting a different colour into each squirt bottle. Use these bottles to direct the dye into the fabric. Be sure to be generous with the dye, and get into the nooks and crannies to avoid a great deal of "white space".
Place each dyed item in a separate plastic bag and tie it closed to let it set for 4-6 hours (the longer they set, the brighter the colours will be). Hand-wash the items in warm, soapy water and hang dry.

To dye fabric with food colouring or Kool-Aid, you must use animal fibre-based fabrics for the dye to take. Wool and silk work best. Food colouring and Kool-Aid dying will only make plant fibres such as cotton look dirty rather than dyed.

Natural Dye Recipes

These dyes can be used on eggs, paper, and fabric. If you intend to eat your dyed eggs, be sure to follow proper food safety precautions, and do not use a mordant! Mordants are only for use with fabrics.
Before you start a fabric project, please read about natural dyes and mordants here.
Be sure to wash your fabric items ahead without any liquid or dryer softeners to remove sizing.

Materials:
large stainless steel pot
wooden spoons
container to collect dye in (old plastic food tubs work well, or a second stainless steel pot)

Colourants (choose from the following):

red (purple) cabbage, chopped (blue)
onion skins (from golden yellow, orange or light brown)
blueberries (purplish blue)
cranberries (deep red)
beets, sliced thinly or grated (red)
1 cup ground coffee (brown)
spinach (green)

Batik Crackle Technique

Ingredients:
prepared dye bath, see above
cotton, linen, wool or silk fabric, prepared as indicated above
parafin wax (use old candles for this!)
large can (such as a coffee or juice can)
large pot or frying pan filled with water
a bowl of cold water
stove
wooden spoons for handling the fabric
newspaper
an iron
optional: rubber gloves

Place the can in the pot of water and place the parafin in the can, so as to make a sort of double-boiler. Heat gently until the wax has melted. Insert fabric into the wax and stir until the fabric is coated. Remove from the can and place in the bowl of cold water to allow the wax to harden. Remove the fabric from the bowl and crumple it until there are lots of cracks in the wax. The dye will seep into the cracks to form a pattern.
Add the waxed fabric to the dye bath and stir. Let soak until the fabric is slightly darker than the shade you wish, then remove and let it dry.
To remove the wax, place the fabric between several sheets of newspapers and iron. The paper will absorb the wax. Repeat with new sheets of newspaper until the wax no longer transfers from the fabric.

For some fun recipes that you can eat, click here.