Itote an tf^e froii-teraiigs Cd(, 
aiiir i\t siiposeir |niiteiite af joints in tjre 
fikrntiaii of JubWes. 
By a. M. WORTHINGTON. 
T his cell consists of an inner porous pot, containing a strong 
solution of caustic alkali, in which the zinc is immersed. 
The outer pot is of iron, and itself forms the kathode of the cell. 
The annular space between the two pots is packed with iron 
turnings, the interstices of which are filled up with the same 
liquid as the inner pot. The hydrogen, instead of forming a 
polarizing layer on the kathode, is intercepted by the rough 
pointed fragments of metal and is liberated in bubbles. 
It is obvious that the same mechanical method of inter- 
cepting the hydrogen can be adopted in a sulphuric acid cell, if 
copper be substituted for iron, and the author has constructed 
cells which differ only from that of Daniell in having the copper 
sulphate solution replaced by fragments of copper turnings in 
sulphuric acid — the chemical hydrogen trap replaced by a 
mechanical trap. He has also used, instead of copper turnings, 
brass filings, which are but slightly acted on by dilute sulphuric 
acid. The acid used was diluted by 12 times its volume of 
water. 
He found that any of these cells would give for several hours 
(3 to 12 hours), through a short external circuit, a current which 
did not vary by more than of its whole value. 
B 
