CHEMICAL INJURY TO THE NERVOUS SYSTEM 259 



311. Anesthetics. Closely related to the narcotics through 

 their peculiar effects upon the nervous system are the sub- 

 stances known as anesthetics. Chloroform and ether are the 

 most common of these, although nitrous oxid, or " laughing 

 gas," is coming into greater use. 



Chloroform and ether are liquids at ordinary temperatures, 

 but are easily changed to vapor when exposed to the air. The 

 person who is to use the anesthetic breathes the vapor into 

 his lungs. In a short time he is overcome by sleep, in the 

 course of which there is complete insensibility to pain. 



