IGNIS FATUUS. 285 



Q. What is the cause of the IGNIS FATUUS, 

 Jack o Lantern, or Will o'the Wisp ? 



A. This luminous appearance (which 

 haunts meadows, bogs, and marshes) 

 arises from the gas of putrefying animal 

 and vegetable substances ; especially 

 decaying fish. 



Q. What gases arise from these PUTREFYING 

 substances ? 



A. Phosphuretted hydrogen gas from 

 putrefying animal substances : and 



Carburetted hydrogen, (or inflammable 

 gas) from fermenting vegetable matters. 



Some persons erroneously think that the 

 AURORA. BOREALIS, or Northern Lights, may be 

 attributed to the same gases, burning in the upper 

 regions of the air. 



Q. How are these gases IGNITED on bogs and 

 meadows ? 



A. By the electricity of the air, the 

 rays of the sun, some accidental spark, 

 the lamp of some traveller, or in some 

 similar way. 



And sometimes from the spontaneous combustion 

 of some dung-heaps, &c. in the locality. 



Q. Why does an ignis fatuus or Witt o' the 

 Wisp FLY/rowi us when we RUN to MEET it ? 

 A. When we run towards an ignis 



