168 APPENDIX. [No. V. 



ness in its employment, and its requiring not only less manipulation 

 than any other battery, but also less cleaning. It can be put into action 

 at a moment's notice, and, after having been used, can be as readily laid 

 by. When in the fluid, it will be quiet till communications are made, and 

 will then possess considerable power. It neither gives off poisonous fumes 

 nor requires the aid of strong acids, and but one fluid is employed ; and, 

 lastly, the amalgamation of the zinc does not require to be renewed. Such 

 are the principal advantages of this battery, and they appeal* to be suffi- 

 cient to entitle it to the very extensive application which it has met with ; 

 but, in conclusion, I wish to be clearly understood that it does not possess 

 the absolute constancy of Daniell's, or the intensity of Grove's battery. 



Smee's Battery was invented through noticing the property which 

 rough surfaces possess of evolving the hydrogen, and smooth surfaces of 

 favouring its adhesion. 



" Thus, whatever metal we use for our negative plate, we take care 

 that it be roughened, either by a corrosive acid, as iron by sulphuric acid, 

 copper and silver by nitric acid, or mechanically, by rubbing the surface 

 with sand-paper. Even by these means the metals are rendered much 

 more efficient; but, to take advantage of this principle to the fullest 

 extent, I cover platinum with finely-divided black powder of platinum by 

 galvanic means ; that is, I place the platinum as the copper is placed in a 

 Daniell's battery, but, instead of employing sulphate of copper in the 

 outer vessel, I use a small quantity of nitro-niuriate of platinum, so that 

 the finely- divided metal is thrown down on the sheet platinum previously 

 roughened by sand-paper. In this way it was also placed on palladium, 

 silver (roughened by nitric acid), plated copper, iron of every sort, and on 

 charcoal, with the same good result ; but no other metal was found to 

 answer for its reception. The metal generally employed is silver, because 

 of its cheapness and its not undergoing any alteration. But whatever 

 metal be used, the principle is the same, viz. the affording a surface to 

 which the hydrogen shall not adhere, but from which it shall be evolved ; 

 and the infinity of the points which are presented by such a surface as 

 above described, appears to be the cause of this excellent result. The pre- 

 paration of the silver is now made a separate branch of a trade, and perhaps 

 it is the first application of the decomposing power of the galvanic battery 

 which was publicly sold. The platinized metal can now be bought ready 

 for use ; but for those who desire to perform this operation a brief descrip- 

 tion is here added. 



" The metal to be prepared should be of a thickness sufficient to carry 

 the current of electricity, and should be roughened, either by sand-paper, 

 as in the case of platinum or palladium, or, when silver is employed, by 

 brushing it over with a little strong nitric acid, so that a frosted appear- 

 ance is obtained. The silver is then washed, and placed in a vessel with 

 dilute sulphuric acid, to which a few drops of nitro-muriate of platinum 

 are added. A porous tube is then placed in this vessel, with a few drops 

 of diluted sulphuric acid ; into this the zinc is put. Contact being made, 

 the platinum will in a few seconds be thrown down upon the surface of the 

 silver, as a black metallic powder. The operation is now completed, and 

 the platinized metal ready for use. However, iron when thus prepared is 



