NITROUS OXIDE, ETHYL CHLORIDE, CARBON DIOXIDE 117 



animal. How is the respiration affected? How does this 

 compare with the action of N 2 ? If you have oxygen, run 

 some of this into the bottle and see if this counteracts the 

 C0 2 . 



Fig. 114. Guthrie's carbon dioxide generator. Two quart milk bottles are used to hold 

 blocks of marble 'and dilute acid (A) and the wash water (bottle B). 



EXPERIMENT VII. 



Nitrous Oxide, Ethyl Chloride, Carbon Dioxide, Increased 

 Atmospheric Pressure, (Decreased Atmospheric Pres- 

 sure). (Frog, Guinea Pig, Rat, Kitten, or Pup.) 



1. Place a frog and a guinea pig (or other small mam- 

 mal see that the frog is protected) in a large bottle ar- 

 ranged as illustrated in Fig. 115. Open the outlet and run 



