Procuring liquid nitrogen locally will be a more challenging task than obtaining a superconductor to experiment with. Check your local yellow pages under "gas compressed industrial & medical" suppliers. Call these suppliers and find one who is willing to sell a small quantity (liter) of liquid nitrogen.
After finding a suitable company, the next problem is finding a container to bring to the supplier to carry and hold the liquid nitrogen. Most suppliers will not sell you liquid nitrogen if you do not have a suitable container. For instance, you would not store liquid nitrogen in a closed vessel, because as the nitrogen evaporates into a gas, dangerously high pressures can build that could rupture or cause the container to explode.
Typically super cold fluids are transported in special containers called Dewar flasks. Dewar flasks are so well insulated they can hold a quantity of liquid nitrogen a few days before it evaporates. In an open non-insulated container the liquid nitrogen will only last a few hours before evaporating completely into a gas. Dewar flasks have a loose fitting top that allows the nitrogen gas to escape rather than build up pressure.
When liquid nitrogen is first poured into a container at room temperature, it will boil furiously until the container (or lining of the container) is brought down to a much cooler temperature. While the nitrogen is boiling furiously, some liquid nitrogen may splatter and splash out of the container. So it is important to keep the mouth of the container pointed away from people while this is happening.
The following is a list of general safety rules to follow when using or handling liquid nitrogen.
- Wear insulating gloves when handling liquid nitrogen.
- Wear safety glasses when using liquid nitrogen.
- Do not touch or allow liquid nitrogen to touch your body.
- Do not touch anything that has been immersed in liquid nitrogen until that item warms to room temperature. If you need to move an item use the plastic tweezers included in the superconductor kits.
- While nitrogen gas is non-toxic, it can asphyxiate by replacing the air in an enclosed space though displacement. Use liquid nitrogen in a well-ventilated area.
- Never store Liquid Nitrogen in a container with a tight fitting lid.
- Be careful not to spill, splash, or overfill liquid nitrogen.