346 Mr Connell on the Action of 



chlorine by a secondary action. When the saline solution was 

 positive and the water negative no oxygen was evolved, but it 

 was employed in causing the secondary appearance of chlorine 

 which was observed at a far earlier period than when the reverse 

 arrangement was adopted. 



When water acidulated with sulphuric acid was substituted 

 for pure water, and used for moistening the asbestus, the effects 

 were much more marked. The saline solution was made posi- 

 tive, and the acidulated water negative ; there was effervescence 

 from both poles, but no smell of chlorine, or bleaching action in 

 thirteen or fourteen minutes. The battery was then reversed, 

 when a distinct smell of chlorine was observed in less than one 

 minute, with slight effervescence from the positive pole and 

 stronger from the negative, and in a few minutes more, test- 

 paper was bleached in the neighbourhood of the positive foil. 



A rather weak solution of iodide of potassium was then ren- 

 dered negative, and distilled water positive, the connexion being 

 made by asbestus moistened with water. A slight effervescence 

 ensued from both poles. In half an hour there was not the 

 slightest discoloration of the liquid in either tube. The battery 

 was then reversed. Instantly the liquid near the positive foil in 

 the saline solution was discoloured, without any evolution of gas 

 from that pole, whilst gas appeared from the negative foil. The 

 iodine gradually increased in the positive liquid. 



These results were quite analogous to those with chloride of 

 potassium. When the solution of the iodide was negative, and 

 the water positive, no iodine appeared, but gas was evolved from 

 each pole by the decomposition of water. On the reversal of the 

 battery the oxygen ceased to come, and iodine appeared in its 

 place by its secondary action. 



The question with what substance the oxygen combines to 

 cause the separation of the chlorine and iodine, depends on the 

 point whether chlorides and iodides are dissolved as such, or as 

 muriates and hydriodates. If in the former state, then the 



