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formed by single metallic Plates and Fluids. 
numerous, and in regular alternation, Galvanic influence will 
be accumulated, analogous, in all its effects, to the influence of 
the common pile. 
Tin, zinc, and some other easily oxidable metals, act most 
powerfully in this class of combinations. 
If pieces of polished tin, about an inch square and ™ of an 
inch thick, be connected with woollen cloths of the same size, 
(moistened, some in water, and some in diluted nitrous acid,) in 
the following order, tin, acid, water, and so on, till twenty series 
are put together, a feeble Galvanic battery will be formed, 
capable of acting weakly on the organs of sense, and of slowly 
producing the common appearances in water; the wire from 
the oxidating surface of the plates evolving hydrogen; and 
the wire from the non-oxidating surface (when of silver) depo- 
siting oxide. 
In all cases, when the batteries of the first class are erected 
perpendicularly, the cloth moistened in acid must be placed 
under the cloth moistened in water ; and, in this arrangement, 
as the acid is specifically heavier than water, little or no mixture 
of the fluids will take place. 
When zinc is employed, on account of its rapid oxidation in 
water containing atmospheric air, three cloths should be used ; 
the first moistened in weak solution of sulphuret of potash, 
(which is possessed of no power of action upon zinc, and which 
prevents it from acting upon the water;) the second moistened 
in a solution of sulphate of potash, of greater specific gravity 
than the solution of sulphuret ; and the third wetted in an oxi- 
dating fluid specifically heavier than either of the solutions. In 
this case, if the order be as follows, zinc, oxidating solution, solu- 
tion of sulphate of potash, solution of sulphuret of potash, very 
