ACTION OF ULTRAVIOLET LIGHT ON VIRUSES 



157 



energy at that wavelength. For viruses, rather large amounts of 

 light are necessary, so that either very intense ultraviolet 

 sources or a monochromator with high aperture must be used. 

 An inexpensive and quite adequate monochromator was de- 

 signed and constructed by Fluke and Setlow (1951) using a 

 large prism of distilled water enclosed with quartz plates and 



2500 



2600 



2700 

 Wavelength 



2800 



2900 



Fig. 6.7. Absorption spectra of T-1 phage and SBMV, taken by Suprynowicz. 

 T-1 has a broad maximum around 2,000 A. The absorption of SBMV extends 

 quite far to the long-wavelength end. 



two 8-in. astronomical mirrors coated with aluminum. The light 

 source was a quartz mercury arc, and each line was isolated by 

 an exit slit covering a bombardment chamber which could be 

 employed either for stirred liquids or dry preparations. An 

 important feature of this kind of work is the measurement of the 

 radiant energy incident on the sample. For routine purposes this 

 can be done with a calibrated photocell, but absolute measure- 

 ments must be made now and again with a thermopile and sensi- 

 tive galvanometer. 



