58 Mr. J. W. Swan. On some Voltaic Combinations [May i 



FIG. 2. 



ci: 



covering the bottom to some depth, over the lead is a layer of NaCl 

 and KC1 previously fused, into which is immersed the lower and 

 closed end of a carbon tube, which forms the + pole. The mouth of 

 the carbon tube is closed by a fire-clay lid luted on, and through 

 which pass two small clay tubes for the inlet and outlet of chlorine. 

 The whole was heated in a small gas furnace. A binding screw on 

 the iron vessel, which served as a connection with the lead, was used 

 as the negative terminal, and another screw fixed on a copper ring 

 surrounding the carbon tube, served as the positive pole connection. 

 The first trial was made without chlorine. Short circuited through 

 1,000 ohms the cell developed an E.M.F. of 0'3 volt. A momentary 

 current of more than one ampere was observed when the cell was 

 short circuited through a low resistance ammeter. Chlorine was 

 then passed through the tubes inside the carbon pole, but no depolar- 

 ising effect was observed, even when the chlorine had a slightly 

 higher pressure than the atmosphere, yet the gas passed through the 

 exposed sides of the carbon tube and through the cement at the top. 

 This experiment was repeated several times with carbon tubes of the 

 smallest possible thickness, and always with the same result. It is 

 evident, therefore, that an absorption of chlorine similar to that which 

 takes place in the Upward cell does not occur when a molten electro- 

 lyte of the kind employed in this experiment is used. 



Exp. 2. As this method of applying chlorine was unsuccessful, 

 another form of apparatus was adopted. The poles were of the 

 same material as in the previous experiment, but the carbon pole 



