452 History of Luminescence 



Dibbits (1864) made a comprehensive study of the spectra of 

 various flames— CO and CN in air, oxygen, and nitrous oxide, H2S 

 and CS2 ^^ in air and nitrous oxide, etc. These spectra are not of the 

 continuous incandescent type, akhough considerable ultraviolet may 

 be emitted, as indicated by Dibbits' observation that some of the 

 flames, especially sulphur compounds, cause fluorescence of quinine 

 sulphate solution.^^ 



The luminescent vapors of phosphorus can be arranged to burn 

 like a flame but it is less often recognized that vapors of other non- 

 metals, such as sulphur and arsenic behave in the same way at a 

 slightly higher temperature, as pointed out by J. Joubert (1874) , 

 K. Heumann (1882) , and many others. All these gaseous chemi- 

 luminescences, representing relatively simple reactions, became of 

 great interest in the twentieth century. 



Chemiluminescence in Solution 



INORGANIC COMPOUNDS 



Observation of chemiluminescence in solution begins with inor- 

 ganic compounds. Placidus Heinrich devoted the fifth section of 

 his book to " Phosphorescenz durch chemische Mischungen " (1820) . 

 He described the luminescence which appears when water or strong 

 acids are added to fresh burnt lime (p. 584) or when corrosive 

 alkalies (K, Na, NH4 hydroxides) are mixed with acids (p. 573-574) 

 or when mercurous nitrate or lead acetate is treated with H2SO4 

 (p. 576) . 



One of the most striking luminescences of this type is the glow 

 which accompanies the laking of freshly prepared lime. Mixing 

 water and calcium oxide produces not only heat but light, a dis- 

 covery of Johann Friedrich Meyer (1764) , who discoursed at some 

 length on light, fire, and heat in his book *° on lime. It became the 

 subject of much discussion in the late eighteenth century, some 

 holding that carbonic acid was replaced by the material of heat 

 during the roasting of limestone, while others held that lime was a 

 simple uncombined substance. The light production was considered 

 by Diz6 (1799) in connection with the then prevalent idea that 

 heat is a substance and responsible for the luminous effects. H. Davy 



and later work indicates that explosive gases like chloroazide (N3CI) luminesce if 

 decomposed slowly. 



^«See E. Pringsheim (1893) and H. B. Dixon and E. J. Russel (1899). 



^® This observation is by no means new as many flames were studied by Stokes 

 (1852) (see Chap. XI) . 



*°J. F. Meyer, Chymische Versuche zur ndheren Erkenntiiisse der Ungeloschten 

 Kalchs, etc., Leipzig, 1764. 



