436 Mr. Smee on the Cause of the Reduction of Metals 



4. This experiment is so much at variance with the electro- 

 chemical doctrine of Dr. Faraday and the inference to be 

 drawn from my cinder experiment, that on rewriting my Ele- 

 ments of Electro- Metallurgy, I felt it to be my duty to exa- 

 mine carefully this hypothesis before 1 adopted or rejected 

 such an important doctrine. For this purpose his experiments 

 were repeated and varied in different ways ; and with alkalies 

 on the negative side I readily and inmiediately obtained the 

 metal on the diaphragm, but failed when neutral salts were 

 used on the negative side, or when solutions of gold and pla- 

 tinum were employed on the positive. A series of experiments 

 were then instituted on the polarity of solid substances inter- 

 posed between two platinum poles. I placed a series of cop- 

 per wires in all directions and situations between the poles in 

 a solution of sulphate of copper, and found that one part of 

 each wire became positive and was dissolved, and another part 

 of the same wire became negative and reduced the metal from 

 the solution; so that all the wires were, at different parts, either 

 dissolving or increasing. I next extended my examination as 

 to the capabilities of platinum wires to become polar, and found 

 that a much greater resistance was effected in this case than 

 when other metals were employed ; still, however, by parti- 

 cular management they were readily made to give off abun- 

 dance of gas (Elements of Electro-Metallurgy, p. 53, 2nd edi- 

 tion). 



5. The polarity of interposed conducting substances having 

 been fully proved, I endeavoured to ascertain how far non- 

 conducting bodies would take on a similar condition, but could 

 not obtain very satisfactory proof on this matter: sufficient evi- 

 dence not being obtained to prove the possibility of interposed 

 non-conducting substances to become polar, I determined 

 not to rely on the investigation for the cause of the reduction 

 of the metals on these experiments, but seek proofs from other 

 causes. 



6. I repeated the experiments made in 1839 and commu- 

 nicated to the Philosophical Magazine in 1840, from which I 

 discovered that porous coke or charcoal, when arranged as the 

 negative pole in dilute sulphuric acid, absorbed a large quan- 

 tity of hydrogen. The mode in which I repeated these expe- 

 riments was as follows : — A piece of well-burnt charcoal or 

 cinder was removed red-hot from the fire and quenched in 

 dilute sulphuric acid, so that all chance of the presence of 

 oxygen in its texture might be precluded. In this state it had 

 no effect on metallic solutions. It was then arranged as the 

 negative pole in dilute sulphuric acid by connecting it with 

 the voltaic battery, when it became charged with hydrogen, 



