Chemiluminescence 443 



worth while to emphasize some of the significant facts which were 

 brought out before 1900. Schonbein's discovery of ozone (1840) 

 and his suggestions^ (1845, 1848) that the ozone found in phos- 

 phorus oxidation is associated with the luminescence process because 

 inhibitors which suppress luminescence are the same as those which 

 destroy ozone," concentrated attention on this substance. He also 

 found (1853) that red phosphorus does not luminesce and no ozone 

 appears on oxidation. 



It was discovered by J. Chappuis (1881) that if yellow phos- 

 phorus is placed in pure oxygen, where no light appears, lumines- 

 cence will begin if ozone is introduced into the vessel; i. e., ozone 

 will raise the maximum luminescence pressure of phosphorus. Chap- 

 puis consequently thought the light was connected with decomposi- 

 tion of ozone. Moreover, ozone itself has been shown to luminesce 

 during thermal decomposition (see a later section) . In addition to 

 Schonbein, N. Blondlot (1868), J. Joubert (1874), and I. Corne 

 (1882) also emphasized the importance of ozone and it was thought 

 to be a universal accompaniment of the luminescence. 



An interesting result of the relation between ozone and phos- 

 phorus was a study by W. Moffatt (1863) of the luminescence of 

 phosphorus in relation to atmospheric conditions. He made obser- 

 vations over a three-year period and found that phosphorus became 

 luminous before storms, when ozone in the air is at a maximum, 

 corresponding to the " south current " of the atmosphere and to 

 magnetic disturbances; non-phosphorescence and minimum ozone 

 occurred during the " north or polar current." Moffatt also observed 

 that the white vapor of phosphorus was attracted to a magnet and 

 concluded: " It appears then that there is an intimate connection 

 between phosphorescence, atmospheric ozone, storms and negative 

 electricity . . . and terrestrial magnetism." 



Most workers agree that during oxidation a trioxide (P4O6) is 

 formed first and that oxidation of trioxide to pentoxide (P2O5) 

 presents all the luminescence phenomena that oxidation of phos- 

 phorus itself presents. T. E. Thorpe and A. E. Tutton (1890) made 

 a special study of trioxide oxidation and pointed out that oxidation 

 of phosphorus to phosphorus pentoxide requires the formation of 

 ozone (Po + 3O2 = P2O5 + O; O + O2 = O3) , whereas the oxidation 

 of phosphorus trioxide does not (P4O6 + 2O2 = 2P2O5) . They could 



*^J. C. G. de Marignac (1845) presented similar ideas. He showed that pure 

 oxygen passed over phosphorus does not result in ozone formation. 



"The work of E. Gilchrist (1923) and H. J. Emelaeus (1926) has indicated that 

 several phosphorus inhibitors are not ozone destroyers. Chappuis (1881) found that 

 phosphorus and vapor of turpentine, a strong inhibitor for phosphorus luminescence, 

 will light momentarily when ozone is admitted to the vessel. 



