Chemiluminescence 441 



to water vapor are L. J. Thenard (1812) , C. F. Schonbein (1845) , 

 L. Gmelin's Handhuch (1849: 116), J. Davy (1833), W. Schmid 

 (1866), H. B. Baker (1885, 1888), and R. H. Brembridge (1889). 

 The Baker work was very carefully done and indicated no lumi- 

 nosity of phosphorus in dry oxygen at any pressure, and no burning, 

 even if phosphorus is raised to its boiling point, a truly remarkable 

 observation. 



T. Ewan (1895) could not obtain consistent curves for oxidation 

 of phosphorus in dry oxygen, and the subject has presented great 

 difficulties, because of the marked effect of traces of water vapor. 

 However, there is no doubt but that the light is dependent on 

 oxygen, i. e., phosphorus luminescence involves oxidation, provided 

 the conditions under which oxidation can occur, are satisfied. 



QUENCHING OF LUMINESCENCE 



The importance of quenching processes has already been pointed 

 out in connection with fluorescence, where the effect of chloride on 

 quinine sulphate was noted by Stokes (1852) . This phenomenon is 

 to be expected whenever luminescence occurs in the gas or liquid 

 phase. The effect of foreign substances in decreasing light emission 

 when electrical discharges occur in gases appears to have been first 

 observed in preparing a mercury barometer that would luminesce 

 (see Chapter VII) . 



The influence of quenching substances on phosphorus lumines- 

 cence is perhaps the oldest of all quenching observation. Boyle 

 (1681) noticed the extinguishing effect of mace and aniseed oils, 

 while Lemery (1686) mentioned camphor as putting out the light 

 of phosphorus. Since that time many workers have turned their 

 attention to this specialized field. The quenching effect of vapors 

 or gases has been observed by C. L. Berthollet (1795), T. Graham 

 (1829) , J. Davy (1833) , H. A. von Vogel (1840) , C. F. Schonbein 

 (1845), M. H. Deschamps (1861), J. Joubert (1874), J. Chappuis 

 (1881), F. Molnar (1883) and M. Centnerszwer (1898). Accord- 

 ing to Graham, whose study was quite extensive, the quenching 

 gases or vapors include CI, S, I, HoS, ethylene, ethyl ether, naphtha, 

 alcohol, acetone, turpentine, camphor, and many others, while Ho, 

 Na, NO2, CO2 and CO may increase the luminescence. Davy stressed 

 the quenching effect of CH4 and pointed out that lack of lumines- 

 cence in pure oxygen might be due to presence of quenchers. Schon- 

 bein held that the quenchers destroyed ozone which accelerated the 

 phosphorus oxidation, and Centnerszwer also believed that ozone 

 was a catalyst for phosphorus oxidation, but found the explanation 

 of quenching more complicated. 



