﻿January 2+tJi, ipOj-] PROCEEDINGS. XXV 



occupied the attention of numerous chemists during the last 

 fifty years. It has been ascribed to various causes, notably to 

 the preliminary formation of an unstable intermediate com- 

 pound. The authors have succeeded in showing that the 

 induction period in question is due to the presence of minute 

 traces of impurities contained in the chlorine, and in the aqueous 

 solution in contact with it. All of the impurities examined 

 which prevent the combination of hydrogen and chlorine have 

 been proved to be substances capable of reacting with chlorine, 

 for example, ammonia and sulphur dioxide. These substances 

 react with chlorine in the presence of light and are gradually 

 destroyed, the action between the hydrogen and chlorine being 

 almost entirely prevented until their removal is complete. The 

 elimination of these poisoning substances in presence of chlorine 

 can also be effected by means of heat. In some cases it even 

 occurs on long standing at the temperature of the laboratory. 



Contrary to what has been previously assumed, pure chlorine 

 is active towards hydrogen, the pure gas from the electrolytic 

 cell only becoming inactive after coming in contact with 

 substances with which it can react. 



The fact mentioned by Bunsen and Roscoe that an active 

 mixture of hydrogen and chlorine becomes inactive on standing 

 is due to their experiments having been performed in glass 

 vessels. On substituting quartz for glass it has been shown by 

 the authors that no such decay occurs. The decay observed in 

 the former case they believe to be due to the slow action on 

 the chlorine of some impurity contained in the glass. 



Ordinary Meeting, February 7th, 1905. 



Professor H. B. Dixon, M.A., F.R.S., Vice-President, 

 in the Chair. 



The thanks of the members were voted to the donors of the 

 books upon the table. 



Mr. R. S. Hutton, M.Sc, and Mr. Charles Oldham 



