42 



DESCRIPTION OF GALVANIC BATTERIES. 



of an iron rod and ratchet wheel, so that the plates may be either 

 partially or entirely immersed in the solution, or raised at plaasure 

 out of it. The connections are so contrived, that by a slight altera- 

 tion the battery is adapted to afford either quantity or intensity of 

 electric power. It is usually made to contain six cells, any number 



of which can be used at once that a given process may require. 

 The exciting fluid is contained in an incorrodible stoneware trough, 

 placed in a mahogany box. A battery of this description, each 

 silver plate of which measures 20 square inches, has sufficient 

 power, when decomposing water, to disengage one cubic inch of 

 mixed gases in 50 seconds, and will heat to redness 4 inches of 

 platinum wire. 



Letter B in figure 20 represents an apparatus for showing the 

 decomposition of water into oxygen and hydrogen gas by the voltaic 

 battery. 



It will be observed in Smee's arrangement that there are two 

 surfaces of zinc, in every pair exposed to the acid, which do not give 

 off any electricity, but when long in use are much acted upon, form- 

 ing a consideration of some value to a manufacturer. 



The silver used is very thin, and liable to crack when taken from 

 its frame, and therefore cannot be made into different constructions 

 of battery in the same manner as we can do with copper. It is 

 also liable to have zinc deposited upon its surface when long in 

 action. 



There is, we believe, no arrangement of battery better known 

 and more used by amateur electrotypists than Smee's, and there are 

 probably none better adapted for small operations ; but it has not 



