Homemade root beer is always a sign of a special occasion at our house, but there’s just something about fall and Halloween that makes this brew especially exciting. The magic (and the science) is in the dry ice. It’s available at most grocery stores, but you usually have to ask for it at the check out stand or at guest services. Made of frozen carbon dioxide, this solid changes directly to the gas phase, without a liquid stage between (a process called sublimation). In addition to the cool fog effect, the dry ice actually carbonates your drink as it dissipates!
(Be sure to use tongs or gloves when handling dry ice as it is actually so cold that it burns the skin on contact. Obviously, this also means you must give adequate supervision for children as you use this substance.)
