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MESSRS. V. H. VELEY AND J. J. MANLET ON 



conducting nature should be avoided, especially if high tension currents are used. So 

 far as can be judged by the description and diagrams of certain previous writers, 

 sufficient attention does not seem to have been given to this essential point. Finally, 

 to avoid contamination of the acid by dust, the cell was closed by a platinum disc. 



(ii.) Temperature Coefficient Cell (fig. 5). 



This was a U tube of 177 sq. centims., cross sectional area, rigidly attached to an 

 insulating stand containing the electrodes, both movable in this case and welded 

 on to platinum wires passing through capillary tubing. The upper ends of these were 

 tied and cemented on to an ebonite block which could be made to rest upon either of 

 two brackets furnished with a hole, slot and plane arrangement similar to that used 

 for a KELVIN galvanometer. When the block rested on the lower bracket (position 



Pig. 5. 



Temperature coefficient cell. 



Electrolytic cell No. 2. 



A), measurements were made of the resistance of the leads and the acid in the bend 

 of the U ; when, on the upper bracket (position B), the total resistance was made 

 up of these factors, together with the introduced length of acid, being double that 

 of the height through which the electrodes had been lifted. To obtain, so far as 

 possible, independent measurements the process of raising and lowering the electrodes 

 was repeated during any one series of experiments. The top of each limb of the 

 U tube was closed with platinum discs. 



