Manchester Memoirs, Vo/. liii. (1909), No. 16- 5 



is under conditions whicli are nearly, but not quite, 

 suitable for chemical action to take place. The gaseous 

 mixtures mentioned only combine, even when moist, at a 

 red heat. Since the experiments were done at 2o'\ they 

 only show that ionization does not produce chemical 

 action in gases which are otherwise unable to combine. 



There remained the possibility that if gases were just 

 on the point of combining, increasing the ionization might 

 accelerate the rate of action. I sought for a case of simple 

 chemical union which would proceed at a manageable 

 temperature, and at a rate, which could be measured. Of 

 those tried, the reaction between hydrogen and nitrous 

 oxide was found to be the most suitable. The gases used 

 were as pure as possible, but dried only by passing through 

 phosphorus pentoxide tubes. They were found to com- 

 bine with great uniformity when heated in clean Jena 

 glass tubes to 530''. An electric resistance furnace was 

 used, consisting of a wide silica tube which formed the 

 heated chamber. It is known that many substances when 

 heated ionize a gas ; lime is fairly efficient, thoria more so, 

 and, of course, radium bromide most of all. In the first 

 experiment two tubes of the same Jena glass, containing 

 the hydrogen and nitrous oxide mixture, were heated side 

 by side. One contained some lime, and in order to make 

 the conditions as similar as possible, an equal quantity of 

 powdered Jena glass was introduced into the other. As 

 soon as the requisite temperature was reached, the action 

 proceeded rapidly in the tube containing lime, the rate in 

 the first five minutes being five times the rate of combina- 

 tion in the tube containing only powdered glass. After 

 I 5 minutes the second tube had caught up the first, and 

 the rates of union were equal up to the completion of the 

 action. With thoria the effect was still more marked, the 

 rate increasing to twenty times the rate in the tube 



