4 Baker, Influence of Moisture on Clwniical Change in Gases. 



increased chemical activity. Accordingly, after running 

 such a lamp, containing speciall)' purified mercury, the 

 current was cut ofif, and shortly afterwards oxygen was 

 admitted. The surface of the metal was found to be 

 covered with red oxide. The temperature of the lamp is 

 less than 150°, and at this temperature there is, under 

 ordinary circumstances, no chemical action between 

 mercury and oxygen. 



In order to test further the question as to whether the 

 ionization of molecules, as distinguished from atoms, can 

 bring about chemical change, I have investigated the 

 action of radium bromide on very pure and dry hydrogen 

 and oxygen. The gases were sealed up with some radium 

 bromide contained in an open silica tube. The containing 

 vessel was provided with a vacuum gauge, by means of 

 which the combination of-^Voth part of the gases could 

 be easily detected. No action whatever was observed, 

 although the substances were left in contact for two 

 months. A further experiment showed that, as was to be 

 expected, very dry air is readily ionized by radium. Two 

 more tubes were then set up, similar to the first, containing 

 mixtures of carbon monoxide and oxygen, one very dry, 

 and the other containing traces of moisture, and although 

 the radium bromide has been in contact with them for 

 more than two months not the slightest contraction can 

 be observed. In these cases therefore ionization produces 

 no chemical change.* 



There is, however, a possibility that ionization may 

 bring about a chemical action in a mixture of gases which 



* Madame Curie lielieved lh;U radium bromide produced ozone in the air 

 in which it is sealed up. The evidence for this statement is thai a smell 

 resembling ozone is oVjserved on opening,' such sealed tuljes. I have opened 

 several such tubes which have been se.iled up for a year or more, but I have 

 only noticed a smell of bromine, which of course when fairt resembles 

 that of ozone. 



