III. Uses Most of the nitrogen used in the chemical industry is obtained by the fractional distillation of liquid air. It is then used to synthesize ammonia. From ammonia produced in this manner, a wide variety of important chemical products are prepared, including fertilizers, nitric acid, urea, hydrazine, and amines. In addition, an ammonia compound is used in the preparation of nitrous oxide (N2O) a colorless gas popularly known as laughing gas. Mixed with oxygen, nitrous oxide is used as an anesthetic for some types of surgery. Used as a coolant, liquid nitrogen has found widespread application in the field of cryogenics. With the recent advent of ceramic materials that become superconductive at the boiling point of nitrogen, the use of nitrogen as a coolant is increasing (see Superconductivity).