286 THE ALLOTROPISM OF CHLORINE. [MEMOIR XX. 



passive iron, chlorine can assume the active or passive 

 state. 



II. Having established the fact of the allotropism of 

 chlorine, I shall then show its connection with the the- 

 ory of substitutions of M. Dumas, and how the most re- 

 markable points in that theory may be easily accounted 

 for. 



The time, perhaps, has not yet arrived for offering a 

 complete mechanical explanation of the assumption of 

 an active or passive state. It may be remarked that a 

 very trivial modification of our admitted views of the re- 

 lation between atoms and their properties is all that is 

 required to give a consistent explanation of every one of 

 these facts. Instead of regarding the specific qualities 

 of an atom as appertaining equally to the \vhole of it in 

 the aggregate, we have merely to assume that there is a 

 relation between its properties and its sides, and that 

 any force which can make it change its position upon its 

 own axis will throw it into the active or passive state. 

 But this is nothing more than the well-known idea of 

 the polarity of atoms. 



Phenomena of the Decomposition of Water by Chlorine 

 in the Hays of the Sun. 



From the various facts which might be employed as 

 offering the means of establishing the allotropism of 

 chlorine, I shall select those which arise from an exam- 

 ination of the phenomena of the decomposition of an 

 aqueous solution of chlorine by the rays of the sun. 



For many years it has been known that an aqueous 

 solution of chlorine undergoes decomposition by the ac- 

 tion of the solar rays. Several of the most remarkable 

 phenomena connected with this decomposition appear to 

 have been overlooked. Among such may be mentioned 

 the singular fact that chlorine which has been thus in- 



