If you are interested in presenting a dry-ice demonstration, an excellent place to start is by visiting Steve Spangler Dry Ice Demo. This website has free demonstrations and directions, and resources for purchase. A favorite dry ice demonstration is the crystal ball. This is an easy but high audience thriller demonstration.
Locally, I get my dry-ice from Air-gas. Call in advance to find out times for pick-up and minimum purchase requirements. Make sure you also purchase some leather work gloves for safety.
On the day you pick up your dry ice, be sure and take a cooler. Wrap the bag of dry ice in layers of newspaper to insulate it. Try to buy the dry ice on the day you will need it. I had to get mine the day before but bought extra to allow for loss overnight. Usually $10 worth is plenty for a day's worth of demos.
Safety precautions:
Do not store your dry ice in a refrigerator!
Crack the windows in your car while transporting dry ice. As it sublimates, it releases carbon dioxide into the air.
To see the demo, click on Dry Ice Demo above or go to the Steve Spangler website listed on the right under Science Fun.
