ao4 Accoiint of Galvanic Combinatlorts 



fcnfe, and of flowly producing the common appearances in 

 water ; the vviie from the oxidating furface ot the plate» 

 evolving hydrogen, and the wire from the non- oxidating 

 furface ^whcn of filver) depofiting oxide. 



In all cales, when the batteries of the firft ckfs are ereded 

 perpendicularly, the cloth moiftened in acid muft be placed 

 under the cloth moiftened in water; and, in this arrange- 

 ment, as the acid is fpecifically heavier than water, little or 

 no mixture of the fluids will take place. 



When zinc is eniploved. on account of its rapid oxidation in 

 water containing atmofnheric air, three cloths llioiild be ufed ;. 

 the firft moiftened in weak folution of fulphuret of polaili, 

 {which is polVcfl^ed of no power of aflion npon zinc, and 

 which prevents it from aiSting upon the water;) the fecond 

 moiftened in a folution of fulphale of polafli, of greater fpe- 

 cific gravity than the folution of fvdphuret; and the third 

 wetted in an axidating fluid fpecifically heavier than either 

 of the folulions. In this cafe, if the order be as follows — 

 zinc, oxidating folution, folution of fulphate of potafli, fc>- 

 lution of fulphuret of polaflx — very little mixture of the fluids, 

 or ehcn^ical action between them, will take place ; and an 

 alternation of twelve feries of this kind forms a battery ca- 

 pable of producing fenfible efl"e6ls. 



III. The fecond clafs of galvanic combinations with fingle 

 plates is farmed, when plates, or arcs, compofcd of a me- 

 tallic fubftancc cap.nble of a(::ting upon fulphurated hydrogen, 

 or upon fulphurets dilTolved in water, are formed into feries, 

 with portions of a folution of fulphuret of polafl) and water, 

 in fuch a manner, that one fide of every plate, or arc, is in 

 contacSl: with water, whilft the oppoi'ite iide is acled on by 

 the folution of fulphuret. Under thefe circumftances, when 

 the alternation is regular, and the number of feries fufti- 

 ciently great, galvanic power is evolved; and water, placed in 

 the circuit with filver wires, is acSled on ; oxide being depo- 

 fitcd on the wire cor.nefted uMth the fide of the plate under- 

 going chemical alteration, whilft hydrogen is evolved from 

 the fide in contact with water. 



Silver, copper, and lead, arc each capable of forming this 

 combination. Plates made from either of ihofe metals may- 

 be arranged with cloths, (moiftened, fomc in water, and 

 others in folution of fulphuret of potafli.) in the following 

 order — metal, cloth moiftened in fulphuret of potalh, cloth 

 inoiiicncd in water, and io on» 



Eight feries will produce fenfible efleiSlsj and the wire 

 from the top of the pile produces oxide. 



Copper 



