262 THE SCIENTIFIC PAPERS OF 



obtain larger effects, and, applying myself to the question, I under- 

 took a series of experiments, the results of which were embodied 

 in a report, which was deemed satisfactory at the time, but has 

 never been published. Now, however, these results appear to 

 reassume some practical value. Starting with the Grove battery, 

 I endeavoured to obtain a form of electrode presenting a large 

 surface of triple contact. Platinum appeared ill suited for the 

 attainment of such an object, and I consequently directed my 

 attention to carbon, such as is deposited in gas retorts, as being a 

 cheaper material, and one that, owing to its porosity and rough- 

 ness of surface, seemed well calculated for the development of 

 surface action. Two pieces of such carbon inserted into inverted 

 glass tubes similarly to the strips of platinum already referred to r 

 gave rise to currents of larger quantitative effect, although some- 

 what inferior in intensity to those produced by the platinum strips. 

 The intensity, however, was greatly increased by subjecting the 

 carbons previous to use to a process of platinisation, or galvanic 

 deposition of pulverulent platinum on their surfaces. The next 

 step was to put carbon into the shape of tubes open at one end 

 and closed at the other. A number of these tubes were inserted 

 in a square box of gutta-percha in TOAVS traversing the box alter- 

 nately in one direction and the other, the box being ultimately 

 placed edge-ways and connected with two chambers covering respec- 

 tively the open ends of the two series of tubes, Plate 22. By 

 filling these two chambers, the one with oxygen, the other with 

 hydrogen gas, and filling the square box containing the tubes with 

 acidulated water, I succeeded in converting the entire carbon 

 surfaces into surfaces of triple contact of carbon, acidulated water, 

 and oxygen and hydrogen gas respectively, owing to the porosity 

 of the material of the tubes ; and it was only necessary to connect 

 the upper closed and protruding ends of the tubes by means of 

 wire in order to constitute the arrangement a gas battery of 

 considerable power. Nevertheless, the current was insufficient 

 for my purpose, though care had been taken to platinise the 

 tubes. 



"With a view of increasing the potential of the currents, I 

 directed my attention to the peroxides of metals, and soon found 

 that peroxide of lead was the one giving the greatest promise of 

 results. The tubes were plunged, after drying, into a strong 



