44^ TRANS, ST. LOUIS ACAD. SCIENCE. 



mentioned time, the tube was entirely colorless, and evidently all 

 iodine had disappeared. What had become of it? 



When reading Mr. C. P. Smyth's Address before the British 

 Association, I recalled these experiments of mine that had been 

 made some time ago. His experiences are quite analogous 

 to my own. In iSSo, his iodine tube showed 148 iodine lines, 

 and 3 exceedingly faint reproductions of the chief liydrogen lines ; 

 "yet, in the present year," he goes on to say, "there is not one 

 iodine line left in that tube, and its spectrum range is filled with 

 nothing but both high and low temperature hydrogen lines of 

 astonishing brilliancy, while of the large amount of iodine gra- 

 nules hermetically sealed into the tube in 1878, only a very small 

 amount of apparently inert dust is now left." Further, he states : 

 "Whether this change is an infinitesimally small part of the 

 progress of everything to turn into hydrogen, and for assisting 

 thereby the whole solar system to explode some day into a so- 

 called and spectroscopically bright-lined hydrogen star, I will by 

 no means weary the Section by enquiring now." 



It is clearly expressed tliat iodine has disappeared from a cer- 

 tain tube ; that, whereas, this tube contained at first only faint 

 indications of hydrogen, it, after the disappearance of the iodine, 

 showed the presence of this element in remarlcable brilliancy or 

 amount. The inference must be that iodine has been decom- 

 posed and that hydrogen is present as product of decomposition. 



As our experimental results are similar in respect to disap- 

 pearance of iodine, it will be of interest for me to describe my 

 analytical manipulations of the contents of my iodine tube, ana 

 to show what my conclusions necessarily were. 



As stated, the iodine had disappeared entirely from my tube. 

 The platinum poles in the tube were much corroded and rough- 

 ened ; during the discharge the ends were constantly at a bright 

 red heat ; the spark itself had a livid appearance, was uncertain 

 in its course, changing frequently. The sides of the tube were 

 afiected as if by hydrofluoric acid, and there was in the tube what 

 seemed to me also only a small amount of dust. 



The tube was opened under water by nipping oft^ the end ; 

 there was a partial vacuum, the water entering and filling it about 

 one-fifth, by a rough estimate. I inferred at the time that the 

 oxygen of the air, originally contained in the tube, had disap- 



