PHOTOCHEMISTRY 281 



is being measured, uncomplicated by secondary thermal reactions. If 

 the quantum yield is nearly unity, one can look for minor compUcations. 

 If the quantum yield is considerably greater than unity, a chain reaction 

 is indicated. If the quantum yield is less than unity, it may be con- 

 cluded either, (a) that some other absorbing material is present and is 

 appropriating some of the absorbed energy, so that it cannot take part 

 in the photochemical reaction; (b) that there is no photochemical reaction, 

 i.e., the energy is being dissipated as heat because there is no other 

 suitable chemical outlet for the energy of excitation; (c) that radiant 

 energy is going partly into chemical energy and partly into heat or (d) 

 that a reverse reaction or side reaction, not measured in the experiment, 

 is consuming the radiant energy. 



REFERENCES. PART 1 



1. Blacet, F. E., and P. A. Leightox. A dry method of microanalysis. Ind. 

 Eng. Chem., Analyt. Ed. 3: 266-269. 1931. 



2. CoBLENTZ, W. W. Various modifications of thermopiles having a continuous 

 absorbing surface. Bur. Stand. Bull. 11: 131-187. 1914. 



3. CoBLENTZ, W. W. Measurements on standards of radiation in absolute value. 

 Bur. Stand. Bull. 11: 87-100. 1914. 



4. Corning Glass Works, Glass Color Filters. Corning, N. Y. 



5. Daniels, F., and L. J. Heidt. A simple capillary mercury vapor lamp. Jour. 

 Amer. Chem. Soc. 54: 2381-2384. 1932. 



6. Daniels, F., J. H. Mathews, and J. W. Williams. Experimental Physical 

 Chemistry. McGraw-Hill Book Company, Inc.; New York, 1934. 



7. DuFFORD, Nighting.\le, and CAL^-ERT. Luminescence of Grignard compounds; 

 spectra and brightness. Jour. Amer. Chem. Soc. 47 : 95-102. 1925. 



8. Heidt, L. J., and G. S. Forbes. Focal isolation versus the monochromator for 

 photochemical work in the ultraviolet. Rev. Sci. Inst. 5: 253-255. 1934. 



9. Hoffman, R. M., and F. Daniels. Quartz capillar^' arc lamps of bismuth, 

 cadmium, lead, mercury, thallium and zinc. Jour. Amer. Chem. Soc. 54: 

 4226-4235. 1932. 



10. Huntress, E. H., L. N. Stanley, and A. S. Parker. The oxidation of 3-amino 

 phthal hydrazide as a lecture demonstration of chemiluminescence. Jour. Chem. 

 Educ. 11: 142-145. 1934. 



11. International Critical Tables 5: (p. 271). McGraw-Hill Book Company, Inc.; 

 New York, 1929. 



12. Leighton, W. G., and G. S. Forbes. Precision actinometry with uranyl oxalate. 

 Jour. Amer. Chem. Soc. 52: 3139-3512. 1930. 



13. ToLMAN, R. C. The temperature coefficient of photochemical reaction rate. 

 Jour. Amer. Chem. Soc. 45: 2285-2296. 1923. 



