56 JOURNAL AND PROCEEDINGS. 



red. The difference between these substances can be further em- 

 phasized by adding some of each to a solution of potassic iodide and 

 starch paste. The chlorine water will give a deep blue coloration, 

 while that contained in the flask will produce no change. At once 

 it becomes evident that some change has taken place in the solution 

 contained in this flask. 



From the fact that the blue litmus becomes red we infer that 

 the solution now contains an acid. Further experiments serve to 

 show that the acid formed is hydrochloric acid, a compound of 

 hydrogen and chlorine in equal proportions. An additional fact to 

 be noted is that the chlorine, as such, has disappeared from the solu- 

 tion during exposure to the sunlight. How then is the hydrochloric 

 acid formed which is found in the solution. The chlorine which 

 enters into its composition is easily accounted for, but no mention 

 of the hydrogen has as yet been made. The only materials which 

 were put into the flask were water and chlorine in solution in it. 

 The only source then from which the hydrogen could be derived is 

 the water, of which it is one of the constituents. 



By the union of the hydrogen of the water with the chlorine to 

 form hydrochloric acid, oxygen should be set free from the water. 

 From purely theoretical considerations, then, we infer that oxygen 

 must be set free by this reaction, and that the bubble in the upper 

 end of the flask must contain it ; this inference will be confirmed if 

 some of the gas of the bubble be withdrawn and tested. Putting 

 all these facts together a satisfactory explanation of bleaching by 

 means of chlorine is obtamed. 



During the actual bleaching no oxygen is allowed to escape 

 free into the air, so that the oxygen liberated by the action of 

 chlorine on water must be consumed in the bleaching process. In 

 this case, as in the case of every chemical reaction where elements 

 are liberated from their compound, they are liberated in the form of 

 atoms, and as atoms are for the most part incapable of an inde- 

 pendent existence, they at once unite with the atoms present for 

 which they have the greatest affinity, so that the oxygen atoms, as 

 they are liberated from the water, at once seize upon the atoms of 

 the coloring matter of the goods being bleached, as being the atoms 

 for which they have the greatest affinity. If this explanation be the 

 correct one, then, as a matter of fact, it is not the chlorine which 

 does the bleaching, although that is the usual way of expressing it. 



