290 THE ALLOTROPISM OF CHLORINE. [MEMOIR XX. 



a sufficient space of time for the disengaged chlorine to 

 be redissolved, and the oxygen be turned out of the 

 bulb, it will be found on keeping the arrangement in 

 the dark that oxygen will slowly disengage as before. 



Now there is every reason to believe that any small 

 amount of oxygen dissolved in the liquid would be ex- 

 pelled with the chlorine at a high temperature. We 

 therefore have to infer that the chlorine after this treat- 

 ment still retains the quality of causing the decompo- 

 sition to go steadily forward. 



The oxygen which thus accumulates in the course of 

 time in the dark, after an exposure to the sun, does not 

 arise from any portion of that gas held in a state of 

 temporary solution, nor from peroxide of hydrogen, nor 

 from chlorous acid in the liquid undergoing partial de- 

 composition. From any of these states a high temper- 

 ature would disen^a^e it. 



o o 



VI. The evolution of gas is not of the nature of a 

 fermentation ; for when it once sets in, the molecular 

 motion is not propagated from particle to particle, but 

 affects only those originally exposed to the rays. 



Let a bulb be filled with chlorine- water which has 

 been exposed to the sun, and in a second bulb place a 

 quantity of the same liquid equal to about one third of 

 its capacity. Fill up the remaining two thirds with 

 chlorine -water which has been made and kept in the 

 dark; and after keeping both bulbs in obscurity for 

 some days, measure the volumes of gas they contain. If 

 the qualities of chlorine w r hich has been changed by 

 exposure were communicable by contact or close prox- 

 imity from atom to atom, we might expect that both the 

 bulbs would yield the same quantity of gas; but this is 

 far from being the case, and in such an experiment I 

 found that the bulb containing the mixture gave only 

 one fourteenth of the gas found in the other. 



