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



observed this fact, but in the experiments of the decomposi- 

 tion of above one hundred different salts, including those of 

 twenty distinct metals which I performed for my work on 

 Electro- Metallurgy, did the results show themselves more or 

 less evidently; and I may state that no electro-metallurgical 

 process can be conducted without the production of these phae- 

 nomena ; and one of the greatest, if not the very greatest diffi- 

 culty which the electro-metallurgist has practically to contend 

 with, is the variation in the strength of the metallic salts sub- 

 jected to decomposition*. 



il. In what way are the metals reduced if they are not 

 transferred from pole to pole? A careful investigation of a 

 solution depositing its metal will at once explain the phseno- 

 menon, for from the negative surface a colourless lighter fluid 

 is seen to rise, which in some cases will destroy the electro- 

 metallurgist's hopes, by causing grooves on the reduced metal, 

 sometimes even to the extent of an inch or more in depth, and 

 the same fluid at other times will cause a sandy or spongy de- 

 posit. From these facts it is evident that water is formed at 

 the negative surface, and that hydrogen probably reduces the 

 metallic salt. 



12. We have now as arguments in favour of the reduction of 

 the metals by hydrogen gas liberated by decomposition of the 

 water, first, the results obtained by the cinder experiment; 

 secondly, the non-transference of the metal; thirdly, the im- 

 perfect transference of the acid ; fourthly, the rise of a light 

 aqueous fluid from the negative pole of a metallic solution. 

 We have, fifthly, besides these cases, the analogy of the reduc- 

 tion of nitrous acid in Grove's battery by hydrogen, for the 

 removal of the gas by the acid gives to it its intensity ; and in 

 this case no other mode can even be supposed by which the 

 decomposition of the acid is effected, save and except its de- 

 composition by hydrogen. The further alteration of theper- 



* November 20, 1844. — 1 happened to call yesterday upon that excellent 

 practical electro-metallurgist, Mr. Home of Newgate Street, and found that 

 he was making an electro-statue of Sir John Crosby, in a mould prepared by 

 the sculptor Mr. Samuel Nixon, from the original model also executed by 

 him. Mr. Home was engaged about the leg, and he stated that he was 

 much troubled by the non-uniform diffusion of the metallic salt through 

 the solution. The mode in which he overcame the difficulty was very 

 simple: he introduced a glass tube every now and then to the bottom of 

 the leg and blew through it, which caused a proper mixture of the exhausted 

 and saturated solutions. The fact was a pretty practical example of the 

 opinions which I have been endeavouring to enforce; it shows that the 

 theorist may in vain attempt to bolster up crude notions, for the practical 

 man must, to be successful, not only adopt, but act upon the true rationale 

 of the phaenomena. Societies may determine that the metals are directly 

 electrolysed, but the practical man will find that their edicts will have but 

 very little effect upon his processes.— A. S. 



