Dry Ice . It is much denser and colder than traditional ice. In addition, Dry Ice doesn't melt - it sublimates.
Sublimation is the process of going directly from a solid to a gas.
The first step in making Dry Ice is to turn the carbon dioxide gas into a liquid. This is done by compressing the C02 and removing any excess heat. The C02 will liquefy at a pressure of approximately 870 pounds per square inch. Next, the pressure is reduced over the liquid carbon dioxide by sending it through an expansion valve. Part of the liquid sublimates, causing the remainder to freeze into snow flakes.