CONSTRUCTION OF THE GALVANIC PILE. 131 
The following details, relate to the construction of the ap- 
paratus. 
Cut the plates out of stout sheet iron, previously cleaned 
and freed from rust, according to the shape indicated by 
figure A ; then bend the plates in the form of cylinders, in 
such a manner that they remain united by the narrow arched 
band, shown in figure b c. The smaller cylinders, c are 
placed in the nitric acid of the porous clay vessels, whilst the 
larger, b, dip in the Weak sulphuric acid which surrounds the 
argillaceous vessels placed in this acid ? - itself being contained 
in a glass Box or bowl. 
The largest iron cylinders have only about O m , 0S12 squares 
of superficies ; two pairs of this nature have carried to a white 
heat a fine platina wire of O ra ,0541 in length, and have very 
briskly decomposed water. The disengagement of hydrogen 
gas by the plate, immersed in the weak sulphuric acid, is very 
feeble, and may be altogether avoided by using plates of tin- 
ned iron. The layer of tin produces with this metal the same 
effect as the amalgamation with the zinc ; it appears even 
preferable. An apparatus constructed entirely, of cast iron 
would most likely be the best. The authors used argillaceous 
vessels of excellent quality made in Berlin, evidently of cal- 
cined porcelain paste. It remains to say that Hessian cruci- 
bles might be employed in case of emergency, A. D. 
Ibid. 
VOL. VIII. — NO. II. 
17 
