Pliospltorescent Glow in Gases. 4G3 



(Lect. Roy. Inst. June 8th, 1888) showed that the glow 

 contains ozone which was detected by the iodide of potassium 

 starch test and others. 



Supposing then that ozone is formed at the pressures at 

 which the variations from Boyle's law seem to exist, it is 

 nevertheless insufficient in itself to account for the glow 

 which is produced at about the same pressure; since if the 

 glow is the result of the formation of oxygen into ozone or 

 vice versa we should expect the phosphorescence to happen 

 whenever the pressure was altered so as to pass over this 

 region, but such is not the case. It is only when a discharge 

 has previously been sent through the gas that phosphorescence 

 occurs in passing over this pressure. It is very probable, 

 however, that the impurities upon which the phosphorescence 

 depends are more readily acted upon in the presence of ozone. 



(20) We may summarise the results obtained as follows : 

 that 



(1) The glow is a volume effect. 



(2) It consists of unelectrified particles. 



(3) It is not the result of the recombination of ions liberated 



by the spark, as these ions travel down the long tubes 

 away from the spark, but are molecules produced in 

 the bulb by the spark directly. 



(4) An electromotive force has no effect upon the glow. 



(5) The glow conducts as it passes through the gas. 



(6) The destructive effect of sparks on the glow is due to 



cathode-rays or fast-moving negative ions. 



(7) The glow is due to impurities, but oxygen is a necessary 



element and most probably ozone, but they are not 

 sufficient by themselves. 



(8) There is an analogy between the glow and thermolumi- 



nescence which is of importance. There is a certain 

 amount of energy stored up in the gas by the passage 

 of the spark. 



(9) The glowing particles resemble in some of their pro- 



perties the emanation from thorium. 



(10) The phosphorescent particles appear to be one kind of 



particles emanating from the spark, quite distinct from 

 those molecules to which the explosive pressure is due. 



(11) The conductivity appears to be electrolytic, depending 



upon the presence of impurities. 



(12) The phosphorescent particles appear to be large mole- 



cular groups formed by the spark, whose existence 

 may be maintained for some time, notwithstanding 

 the bombardment from the molecules of the gas, in 

 consequence of repulsion which they must exert on 

 molecules that approach them. 



