C. J. p. SPRUIT AND A. SPRUIT-VAN DER BURG 105 



identical, however, and the difference is well outside the limits of 

 experimental error. It is nevertheless tempting to identify at least one 

 of the emitting molecular species with the main end product of 

 the chemiluminescent reaction, methylacridone. As the fluorescence 

 spectrum of this compound, recorded in Fig. 5, has been measured 

 at room temperature, it is not impossible that the higher temperature 

 during the reaction is responsible for this broadening. An examina- 

 tion of the absorption spectrum of methylacridone at 94° C indeed 

 shows such a broadening in the absorption, but tlie effect does not 



400 



440 



480 



520 



560 



600 m^ 



Fig. 6. A comparison of the low-temperature chemiluminescence spectrum of 



dimetliylbisacridinium nitrate ( ) with the fluorescence spectrum of this 



compound ( ). 



seem to be sufficient to explain the broadening of the high-tempera- 

 ture chemiluminescence spectrum. 



The nature of the second emitting molecule is not known. It cer- 

 tainly is not dimetliylbisacridinium nitrate, as its spectrum extends 

 much more to the violet than does the fluorescence spectrum of that 

 compound, Fig. 6. 



x\t this point it appears advisable to point out some sources of con- 

 fusion to those examining emission spectra of colored solutions. As a 

 rule, the emission spectra, such as fluorescence and chemiluminescence 



