Manchester Memoirs, Vol. liii. (1909), No. 16. 3 



the presence of liquid drops of water, or drops of any 

 liquid of high specific inductive capacity, would be 

 sufficient to cause a loosening of the tie between the atoms, 

 and this might result in chemical combination of the 

 partially freed atoms to form new molecules. He showed 

 in the same paper {^Phil. Mag., 36, 321) that drying a gas 

 very completely stopped the passage of a current of 1,200 

 volts. In the same year I was able in the same way to 

 prevent the passage of discharge from an induction coil, a 

 discharge which would traverse a spark gap of three times 

 the distance in undried gas. 



Shortly after the discovery of Rontgen rays it was 

 found that they would ionize a gas through which 

 they passed. At the time it was thought that this 

 ionization was similar to that taking place in electrolysis. 

 If this were so the rays would probably cause chemical 

 union to take place even in a dried gas, and accordingly 

 Prof. Dixon and I undertook some experiments on the 

 subject which were published in a joint paper {CJieni. Soc. 

 Jour., 1896). The results were negative, no chemical 

 action could be detected. Since that time the ionization 

 of gases has been shown to be of quite a different nature. 

 The negative ion has been shown to be a particle of the 

 mass of irnnr^^ ^^^^ °^ ^^^ hydrogen atom ; the positive 

 ion is the residue, but whether it is the residue of an atom 

 or of a molecule seems to be still uncertain. Since the 

 ionization of gases is different from that in electrolysis 

 the retention of this term is much to be deprecated. 



In order to illustrate the possibility of positive ions 

 being charged atoms, and not molecules from which an 

 electron had been split off, I devised a new experiment. 

 It is known that mercury vapour in its ordinary state 

 contains atoms only. It occurred to me to try if the 

 charged ions in the mercury vapour lamp had any 



