106 



Mr. Shelford Bidwell 



[May 5, 



in the surrounding air. This, I believe, is generally admitted. I do 

 not know whether slowly oxidising phosphorus has the same effect. 



If it is conceded that the atmospheric gases are dissociated by 

 electrical discharges, and that the presence of such dissociated gases 

 somehow brings about the dense condensation of water vapour, we 



Tnm ft 1 ^ 



/ 



r 



\ 



Spark Bottle. 



I, Ingress tube ; E, egress tube ; W, wires to induction coil ; 

 S, spark gap. 



may still regard the electrified steam jet as affording an illustration 

 of the abnormal darkness of thunder-clouds. 



Perhaps another source of dissociated atoms is to be found in the 

 ozone which is generated by lightning flashes. A molecule of ozone 

 consists of three atoms of atomic oxygen, while one of ordinary 

 oxygen contains only two. Ozone is an unstable kind of material 



