Chemiluminescence 455 



producing process in animals and plants had been imitated in a test 

 tube. 



In the meantime, Trautz (1905) discovered many more biological 

 substances to be chemiluminescent,^^ Guinchant (1905) noted chemi- 

 luminescence of uric acid and asparagin, Weitlaner (1911) of sub- 

 stances in humus, and McDermott (1913) of substances in urine 

 and the anaerobic alkaline hydrolysis products of glue and Witte's 

 peptone, when oxidized by strong oxidizing agents like H2O2, hypo- 

 chlorite, etc. Later many more organic chemiluminescent substances 

 were discovered, among them the most brilliant and important 

 aminophthalichydrazid (luminol) , by H, O. Albrecht in 1928, and 

 dimethyldiacridinium nitrate (lucigenin) , by K. Gleu and P. Petsch 

 in 1935. At this time, research in chemiluminescence was largely 

 concerned with designation of the excited molecule and the mecha- 

 nism of the light emission, a field without the scope of this history. 



No book devoted entirely to chemiluminescence (apart from 

 studies of animal light) appeared in the nineteenth century, and in 

 fact even today the subject has been treated as a whole only in 

 articles or in chapters of larger works. The early twentieth century 

 was a period of expanding interest in the subject. A systematic 

 search for new chemiluminescent reactions was made by Max 

 Trautz, whose general article of 110 pages, " Studien iiber Chemi- 

 lumineszenz " was published in the Zeitschrift filr Physikalische 

 Chemie for 1905. The relation of crystalloluminescence and tribo- 

 luminescence to chemiluminescence was included and all aspects 

 treated at length. 



Since then many new chemiluminescent compounds have been 

 discovered, of which the list includes the organic sulphur com- 

 pounds of Delepine in 1910; oxidative reactions at the surface of 

 siloxene compounds by H. Kautsky in 1921, supplying beautiful 

 examples of sensitized chemiluminescence (Kautsky and H. Zocher, 

 1922; Zocher and Kautsky, 1923) ; aminophthalichydrazid (lumi- 

 nol) , by H. O. Albrecht in 1928; dimethyldiacridinium nitrate 

 (lucigenin) , by K. Gleu and P. Petsch in 1935; and metal phthalo- 

 cyanin and metal porphyrin compounds, by J. H. Helberger in 

 1938.« 



Spectroscopically the chemiluminescences in solution exhibit 

 moderately narrow bands in different regions of the visible spectrum, 

 as pointed out by Radziszewski (1880) in his early studies. Every 

 color is represented; luminol luminescence is blue, lucigenin yellow, 



<^ References to the many twentieth-century studies on chemiluminescence men- 

 tioned below will be found in the books of E. N. Harvey, The nature of animal light 

 (Philadelphia, 1920) and Living light (Princeton, 1940) . 



