[lubovich & pearen] INFRA-RED SPECTROSCOPY 



205 



'0 20 30 40 50 60 70 80 MM 



Fig. 21 



considerably short exposure, as in the case of (c), appeared as usual, 

 black, and longer exposure made them white too {d). Infra-red lines 

 did not appear at all as black, being masked by the continuous back- 

 ground possessed by every gaseous spectrum, but the latter continuous 

 background played a certain role, "solarizing" the plate, and as a 

 result the infra-red lines appeared as white. Still longer exposures 

 brought out more infra-red lines. 



In the course of the work we tried to follow exactly Millochau's 

 method, using malachite green instead of Dicyanin A and previously 

 "solarising" the plates, but the results obtained were not so satis- 

 factory as in the case of Dicyanin A, being used with no previous 

 "solarization." 



In concluding I wish to thank Professor McLennan, who sug- 

 gested the problem, for his advice and assistance during the course of 

 the experiment. 



DIVISION II 



By Miss E. M. Pearen 



Part I. A Study of the Infra-red Spectrum of Mercury by 



Means of a Thalofide Cell 



In the investigation of the infra-red spectrum of mercury by 

 McLennan and Shaver^ already referred to, it w as shown that the 

 ^McLennan and Shaver, Proc. Roy. Soc. A. Vol. 100, 1921. 



