130 
CONSTRUCTION OF THE GALVANIC PILE. 
ART. XX.— UPON A NEW CONSTRUCTION OF THE GAL- 
VANIC PILE. By Wohler. 
To obtain the greatest galvanic effects, Mr. Grave, in his 
later days, substituted for the gigantic and inconvenient ap- 
paratus that had been used up to his time, a pile, composed 
of small cells or cylinders, of porous pipe clay, baked, filled 
with nitric acid, and placed in other vessels, containing dilute 
sulphuric acid. In the nitric acid were placed thin platina 
plates, and in the diluted sulphuric acid, amalgamated zinc 
plates, the communication being established by means of thick 
copper wire. 
The expense of the platina plates has limited, up to the pre- 
sent time, the use of these convenient and energetic piles. 
Professor Poggendorff has since discovered that the platina 
plates may be replaced, with almost equal success, by plates 
of iron ; but subsequent researches have further shown to 
Messrs. Wohler and Weber, that these same iron plates might 
be substituted for the plates of amalgamated zinc. They 
have thought that the iron in concentrated nitric acid, (the 
concentration of the nitric acid ought to be to such a degree 
as no longer to attack iron ; for this purpose a mixture may 
be employed, of fuming nitric acid, and one part to one and 
a half of common nitric acid,) acts in relation to the iron in 
the dilute sulphuric acid, (one to four of water) as platin a 
does to zinc. Their opinion has been confirmed, and they 
have obtained, by the simple aid of iron in the two liquids, 
a pile of the greatest force, a phenomenon of the highest inter- 
est for the theory of the pile in general, and for the study of 
the galvanic actions of iron in particular. One can now easi- 
ly establish for himself a very powerful galvanic pile, with 
a constant current. All that is required, is a small number 
of bent sheet iron plates, and some argilaceous vessels. The 
nitric acid is the only expense of any consequence. 
