MI.M..IU X1X.J MODIFIED C11LOU1NE. 271 



MEMOIR XIX. 



ON MODIFIED CHLORINE. 



From the Philosophical Magazine, July, 1844. 



[This Memoir was read at the meeting of the British Association held at Cork, 

 1843. The concluding paragraphs were subsequently added.] 



CONTENTS : Description of the experiment. The change in the chlorine 

 w not transient. There are two stages in the phenomenon. Rays are 

 absorbed in producing this change. The indigo ray is absorbed. The 

 action is positive from end to end of the spectrum. The indigo ray 

 forms hydrochloric acid and also produces the preliminary modifica- 

 tion. Change in other elementary bodies. Verification of these results 

 with the chlor-hydrogen photometer. 



CHLORINE gas which has been exposed to the daylight 

 or to sunshine possesses qualities not possessed by chlo- 

 rine made in the dark. 



This is shown by the circumstance that chlorine which 

 has been exposed to the sunshine has obtained from 

 that exposure the property of speedily uniting with hy- 

 drogen gas, a property not possessed by chlorine made 

 and kept in the dark. 



This quality gained by the chlorine arises from its 

 having absorbed chemical rays corresponding in refran- 

 gibility to the indigo. It is not a transient, but appa- 

 rently a permanent property, the rays so absorbed be- 

 coming latent, and the effect lasting for an unknown 

 period of time. The facts here presented will be inter- 

 esting to chemists, because they plainly lead us to sus- 

 pect that the descriptions we have of the properties of 

 all elementary and compound bodies are either inaccu- 

 rate or confused. These properties are such as bodies 



