2 Baker, hiflncuce of Moisture o?i Chcviical Change in Gases. 



heat without explosion, and lastly in 1907 my wife and I 

 obtained nitrogen trioxide as an undissociated gas for the 

 first time by carefully drying the liquid, and evaporating 

 into a dried atmosphere. 



The amount of water required to bring about these 

 chemical actions is extremely small. Mere passing of a 

 gas through long columns of phosphorus pentoxide is 

 insufficient to prevent chemical action, and this treatment, 

 according to the determinations of Prof. E. W. Morley, 

 leaves only 3 mg. of water in 1,000,000 litres of the gas. 

 For extreme dryness to be attained prolonged contact of 

 phosphorus pentoxide is necessary. Of the reactions 

 which have been tried with the utmost attention to purity 

 of the substances, only a few, the combustion of carbon 

 bisulphide, cyanogen, and some hydrocarbons in oxygen 

 appear to be unaffected by the presence of small traces of 

 moisture. 



Many explanations have been attempted of the 

 influence of moisture on chemical action. Dr. Armstrong 

 suggested, during the discussion on my first paper at the 

 Chemical Society in 1884, that all chemical actions were 

 electrolytic in character, and that in ordinary reactions in 

 gases the water vapour, impure as it would be, served as 

 electrolyte. I believed in 1902 that I had obtained 

 evidence in favour of his view, because on heating a 

 mixture of very pure hydrogen and oxygen not completely 

 dried, water was produced, doubtless very pure, but no 

 explosion resulted. Prof Dixon has since pointed out 

 that the want of explosiveness in the wet mixture may 

 have been due to the gases having been diluted b}' the 

 steam formed and in presence of a neutral gas no 

 explosion would be expected. 



Sir J. J. Thomson in 1893 .showed that if the com- 

 bination of atoms in a mcjlecule is electrical in its nature, 



