356 THE POPULAR SCIENCE MONTHLY. 



electrical storage batteries, or accumulators, as they are sometimes 

 called. 



The employment of these names for the apparatus is very un- 

 fortunate. They are the cause of the popular idea that electricity, 

 which is considered as a subtle, indefinite, and intangible some- 

 thing, is stored up in them, as valuables are stored in a vault. 

 The commercial current electricity can not, in large quantities, 

 be stored and still preserve its character. It has but a flitting 

 existence, and is no sooner produced than it dissipates itself and 

 is converted into some other form of energy. It was because of 

 this momentary existence that science had to wait so long for an 

 accident to reveal to Galvani that such a thing could exist. 



The energy which a current may at any instant be said to 

 possess is immediately transformed into heat in the circuit, which 

 will under certain conditions produce light ; into chemical energy ; 

 into motion, which may or may not produce sound ; or into mag- 

 netic and electrotonic conditions. The last may either be perma- 

 nent or have the same evanescent existence as the original current. 



When electricity is employed to charge a storage battery, only 

 that part which is transformed into chemical energy is used. The 

 rest is dissipated. The battery, then, instead of being a place 

 where electricity is laid away, is a place where chemicals are left 

 by the current, with the expectation that they will in turn pro- 

 duce a current when called upon. This may seem a fine distinc- 

 tion, but it is only apparently so. For instance, the current 

 might be produced by a dynamo turned by Niagara water-power. 

 The chemical left by it might be zinc deposited from a solution of 

 zinc sulphate. This might be transported, preserved, bought and 

 sold, and finally be employed by some physicist to produce another 

 current. Were the electricity itself stored in its original form, 

 then the imaginative reader can best tell what would become of 

 it and how it must be handled. 



To understand this transformation more clearly, and to obtain 

 a clear idea of what goes on in a storage battery, one must first be- 

 come acquainted with that part of electricity which treats of the 

 phenomena resulting when a current of electricity passes through 

 a liquid. This is called electrolysis, and the liquid through which 

 a. current can be made to pass is called an electrolyte. 



If a current of electricity flows into a liquid solution of any 

 metallic salt by means of a wire, and if, after traversing it, it 

 flows out through another wire, then it will, by its passage, sepa- 

 rate the salt into two parts and deposit the metal upon the latter 

 wire. 



If, for instance, the solution be one of silver cyanide, then silver 

 will be deposited on the second wire. If a brass fork be connected 

 with this wire and dipped in the solution, then it will receive a 



