Pressure Reversals 189 



of the tube where the ozone may be catalytically decomposed. In ad- 

 dition the accumulation of oxides of nitrogen on the walls will change 

 the nature of the surface and therefore the nature of the discharge is 

 apt to be altered. The discharge tends to be concentrated into a few 

 brushes in which the more intense activation allows less and less ozone 

 to exist. Finally, when the whole wall is all covered a further change 

 in the discharge occurs. The adsorbed molecules are more or less 

 driven off and decomposed, explaining the pressure increase. There is, 

 doubtless, a very complicated state of affairs. This hypothesis gives an 

 explanation of the observed facts. It is now being further tested ex- 

 perimentally. 



