of Edinburgh, Session 1868-69. 
507 
the palladium moving outwards; after some time it returns. 
Similar observations, as with the palladium clipped in stand, but 
made with the junction out of the liquid, showed a decided move- 
ment depending on the relative position of the plates. Seeing 
the palladium moved, although firmly clipped in a socket out of 
the liquid, it was evident the motion could be examined without 
the use of compound plates. 
After devising several arrangements in order to examine with 
ease the motion of the plate, the following plan was found to be 
the best in practice : — 
The electrodes of palladium and platinum were firmly clamped 
in the little vice represented by D, and arranged as shown in the 
figure, where A represents the palladium and B the platinum. To 
the lower edge of the palladium plate a narrow strip of the same 
metal is fused by the oxyhydrogen blow-pipe; the strip is of such 
a length as to project above the level of the acid liquid when the 
plate is immersed. To the end of the strip of palladium a thread 
of glass is fused so as to have a radius in all of 40 or 50 centi- 
metres ; the arc of a divided circle of the same radius, on a piece 
of cardboard, is supported by a stand at the extremity of the index. 
