frjfnied by Jingle MeUiilic Plates and Fluids. 305 



Copper is more aiiive, in thisdafsof batteries, than filver; 

 and filvcT more active than lead. 



IV". The third and niott powerful clafs of galvanic batte- 

 ries, conftrufted with fluids and finale metals, is formed 

 when metallic fubltances oxidahle in acids, and capable of 

 acting on iblutions of fulphurets, are connected, as plates, 

 with oxidatinc fluids and folutions of fulphuret of potafli, ia 

 fnch a manner, that tiie oppolite fides of every plate niav be 

 andcrgoiHg di'd'erent chemical changes; the mode of aUer- 

 nation being regular. 



The fame metals that aft in the fecond clafs may be ufed 

 in the third clafs; and the order of their powers is liniilar. 

 The pile may be ererted in the fame manner as the pile with 

 zinc in the firfl clafs; the cloths moiflcned in acid being 

 feparated from thofe moiltened in lohui(ui of fulphuret by a 

 third cloth foaked m folution of fulphate of potafli. 



Three plates of copper or fiber, arranged in this manner, 

 in the jull order, produce icnfible eOeiSls ; and twelve or 

 thirteen feries are capable of giving weak fliocks, ajid of 

 rapidly producing o;as and oxide in water; the wire connected 

 with the oxidating end of the apparatus evolving hydrogen; 

 and the wire attached to the end a6ling on the fulphuret, 

 dcpofiting oxide when compofed of filver, and generating 

 oxygen when of gold. 



V. In all the llnglc metallic piles conflrufted with cloths, 

 tlic aftinn is very traufient : the decompofition of the acids, 

 and of the ful|)hurets, is generally completed in a few mi- 

 nutes ; and, in confequence, the galvanic influence ceafes to 

 be evolved. The arrangement of all tlie diflcient feries mav, 

 however, (bv means of an apparatus cuuftrafted after the 

 ideas of count Kumford,) be made in fuch a manner as to 

 give confiderable permanency t«) their efl'efts. This appa- 

 ratus is a box, covered uiih cement iucapable ofcoudu^lin'^; 

 electricitv, and compofed of three pieces of mah(igany, each 

 containing grooves capable of receiving the edges of the dif- 

 ferent plates proper for conipofing the feries. One half of 

 thele plates muft be comjKjfed of horn or glais, and tin; oilier 

 bialf of metallic fubfiancci ; and the conduAor.-. of tlcAvicity, 

 and the non-cr;nduCtors, mull be alternately ceuien'.ed into 

 the gr()(ncs, fo as t<» form water-tight eel's. 



VVheii the apparatus is ufed, thefe cells are filled, in the 

 galvanic order, with diHercni i'olulion'<, accorJuig to the clafs 

 of the eumbinaiion ; and conmelcd in pairs with each oilier, 

 b\' (lijw of moiUcncd cloih, earned over the non-coududting 

 plates. 



A combination of fifty copperplate.-, arranged :n this man- 

 ner. 



