424 Mr. K W. Wood on\the Absorption. Spectrum of 



For the preliminary investigation four tubes of similar 

 size were prepared (1, 2, 3, & 4, fig. 1) containing equal 

 amounts of iodine, but successively increasing amounts of 

 bisulphide of carbon. 



Fig. 1. Fig. 2. Fig. 3. 



AA 



i 



XI 







^ 



12 3 4 



These tubes were successively heated until their contents 

 were homogeneous, and their absorption spectra observed. 

 No. 1 showed the lines almost as distinctly as iodine alone : 

 in No. 2 they were fainter but still visible : it was with 

 difficulty that they could be seen in No. 3, while in No. 4 they 

 were entirely absent. No. 4 was then opened, and a little more 

 iodine added. On reheating, the lines appeared. Variations 

 in the temperature had no apparent effect. A mixture which 

 at 300° snowed the lines faintly, showed no change when 

 heated to 350°. 



A large number of experiments were tried with varying 

 amounts of iodine, and with various solvents such as chloro- 

 form, liquefied sulphur dioxide, and water, and all were found 

 to act in the same way. It was difficult to get reliable results 

 with water owing to its action on the glass with formation of 

 iodides. 



To determine the effect of a greater pressure with less 

 density, an apparatus (fig. 3) was constructed of glass, in which 

 ressure could be developed by the electrolysis of water. 



he long arm, which contained the iodine, was heated in the 



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