In the late 19th century, Xenon was discovered. In 1940, a scientist J. H. Lawrence discovered the anesthetic properties of Xenon. J. H. Lawrence first conducted an experiment on mice and discovered the properties of narcotic in Xenon. After few years of that experiment Xenon was tested for the usage of anesthetic on human beings by Cullen and Gross. Cullen and Gross used Xenon with 100 percent of oxygen and after denitrogenation on 81 years old man and 38 years old woman. With the help of this experiment, they concluded that Xenon possesses the characteristics of producing anesthesia.