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The loiijj-corituiued Action of the Eleetric Disch(ir<jc 



on Iodine. 



By C. LuEDEKiNG, Ph.D. (Leipzig). 



Some time ago, the author attempted the study of the eflects 

 of the electric discharge on iodine vapor, when continued over a 

 long space of time. The researches of V. Meyer showed that 

 with increasing temperature the vapor density of iodine becomes 

 rapidly less than what is demanded by theory, finally reaching 

 two-thirds of the theoretical value ; a fact explained by the par- 

 tial supposed dissociation of molecular into atomic iodine. 



Later, J.J. Thompson {Proc. Royal Soc, vol. xiii., pp. 343- 

 345), showed that the silent discharge produces the same phe- 

 nom-ena of anomalous densities that were observed by V. Meyer 

 for higher temperatures. Several hours of time were necessary 

 for the vapor to regain its normal density. 



It was desired by the author to act upon the vapor of iodine, 

 through along period of time, by means of the electric discharge, 

 and subject the result to analysis, with a view to establishing, if 

 possible, any changes brought about. 



Four Grove cells, of Browning's make, were used as electro- 

 motive force. The circuit was passed through a Ruhmkorf coil 

 capable of giving sparks two inches long by this arrangement ; 

 the wires of the coil were connected with heavy platinum wires, 

 sealed in a small heavy glass tube, with their ends opposite, and 

 i inch apart from one another. In this tube 0.036 grm. of iodine 

 was sealed hermetically. By gentle heat it was then vaporized 

 in part, the contents assuming the appearance of an intensely deep 

 violet color. The spark was now passed incessantly for three 

 weeks, day and night, and the character of the light phenomena 

 watched as carefully as possible. As the experiment advanced 

 the color of the contents of the tube gradually changed, losing 

 the rich deep violet tint it had at first, very much resembling 

 bromine vapor in appearance, and, passing through this stage, 

 becoming more and more faint, until, at the end of the afore- 



