ELECTRIZERS. 57 



required for use. The zincs should, as in other batteries, be 

 rinsed and set aside to drain. The detail of these minute points 

 may appear tedious, but it will be found that attention to these 

 matters will prevent disappointment, and the operator will be 

 enabled to insure the proper action of his apparatus. 



Of the terms POSITIVE, and NEGATIVE. There is nothing which 

 has a greater tendency to confuse the mind, with regard to 

 voltaic apparatus, than the terms positive and negative end of a 

 battery. "The fundamental principle." observes Mr. Walker, 

 " which cannot be too strongly enforced, is, that the passage of 

 the electricity is from the zinc to the copper." This, of course, 

 refers to the common forms of battery Cruickshank's, Babing- 

 ton's, &c. In the arrangement of Smee, the passage of the 

 electricity is from the zinc to the silver ; in Grove's battery, 

 from the zinc to the platinum. " The positive is the end where 

 the electricity leaves the battery ; the negative where it re-enters 

 it. The direction taken by the current being ascertained by the 

 mere inspection of the situations of the two metals in a cell, the 

 other points follow as a necessary consequence." Now, taking 

 the Smee's battery as an illustration, it must be clear, that as 

 the electricity passes from the zinc to the silver, it would leave 

 the battery by the wire attached to the silver plate, and having 

 passed through the interposed apparatus, would return to the 

 battery by the wire attached to the zinc plate ; the silver, which 

 is the negative metal, forming the positive end of the battery ; 

 and the zinc, the positive metal, forming the negative end. In like 

 manner with all the batteries we have described, the zinc, 

 though the positive metal, is the negative pole. 



ELECTRIZERS. 



There is another method which has been devised for the 

 topical application of Voltaic Electricity, and which, from the 

 name of their inventor, usually pass under the title of Har- 

 ringtons Electrizers. They are plates of copper and zinc, or 

 silver and zinc, made in different shapes. In tooth-ache, for 



c 5 



