Mobility of the Positive Ion in Flames. 789 



combustion, jarge neutral bodies are formed which combine 

 with extreme rapidity with small ions ; if no condensable 

 products are formed, there is no tendency to cluster. 



Besides the well-known electropositive nature of hydrogen 

 in the electrolysis of solutions, there is a certain amount of 

 experimental evidence supporting the view that the high 

 temperature ion is actually an atom of hydrogen. The 

 strong tendency of hydrogen to carry a positive charge is 

 exhibited by some experiments on the positive discharge from 

 sodium phosphate made by Horton *. It was found that on 

 introducing hydrogen into the exhausted discharge-tube, the 

 positive current was increased 80 times. Carbon monoxide 

 (which on other grounds Horton considers to be the positive 

 carrier in his experiments) only increased the current 7 times. 

 Garrett f measured the mass of the positive carrier from 

 aluminium phosphate, and found it to be that of an atom of 

 hydrogen. Richardson { discovered that in the case of 

 heated platinum a large amount of hydrogen escapes in the 

 form of positive ions. His later experiments, which con- 

 sistently reveal a positive carrier of specific mass about 30, 

 seem to indicate that these charged atoms (or molecules) of 

 hydrogen have a very strong tendency to combine with some 

 larger molecule. The only other case in which the positive 

 earlier has been investigated is that of canal rajs. Here 

 again a particle of unit mass always occurs, no matter what 

 may be the gas experimented on ; in addition to this particle, 

 the atoms of the gas occur with a positive charge. On the 

 whole, it seems most probable that the small positive carrier 

 v Inch so often occurs is actually an atom of hydrogen. As 

 hydrogen is present in the flame, there is no difficulty in 

 explaining the source of the positive carrier ; how to explain 

 the method by which the hydrogen atoms acquire their charge 

 is more doubtful. 



It has been suggested frequently that ionization in a flame 

 is brought about by chemical action induced by high 

 temperature. In a recent paper Bloch § has examined a 

 number of low-temperatuie flames (the so-called " phosphor- 

 escence " of sulphur, phosphorus, &c), and found that, -with 

 the sole exception of phosphorus, chemical action is not 

 accompanied by ionization. It is, of course, quite possibte 

 that at higher temperatures chemical action is so intense that 

 ionization is produced by mechanical rupture of the surface 



* Horton, Camb. Phil. Soe. xvi. p. 1 (1910). 

 t Garrett, Phil. Mag. Oct. 1910. 

 1 Richardson, Phil. Trans. A. p. 207 (190G). 

 § Bloch, Ann. de Chim. et Vhys. April 1911. 



