280 CHOKE DAMP. 



called CHOKE damp, because it chokes 

 (or suffocates) every animal that inhales 

 it. (see p. 264). 



Q. What is marsh-gas or PIKE-DAMP ? 



A. Carburetted hydrogen gas accu- 

 mulated on marshes, in stagnant waters, 

 and coal pits; it is frequently called 

 "inflammable air." 



Q. What is CARBURETTED HYDROGEN GAS ? 



A. Carbon combined with hydrogen. 



Q. How may CARBURETTED HYDROGEN GAS 

 be PROCURED on marshes ? . 



A. By stirring the mud at the 

 bottom of any stagnant pool, and col- 

 lecting the gas (as it escapes upwards) 

 in an inverted glass vessel. 



Q. What is COAL GAS ? 



A. Carburetted hydrogen extracted 

 from coals, by the heat of fire. 



Q. Why is carburetted hydrogen gas called 

 FIRE-DAMP, or inflammable air ? 



A. Because it very readily catches 

 fire and explodes, when a light is 

 introduced to it. 



Q . Why is carburetted hydrogen gas frequently 

 called MARSH GAS? 



