Mr. H. F. Morley on Grove 1 s' Gas-Battery. 273 



4. In one experiment Mr. Grove arranged his platinum 

 plates, which I believe were platinized, in sueh a way as jast 

 to cut the surface of the liquid in the tubes : he got a strong 

 current until the liquid rose above the platinum, when it be- 

 came very weak. M. Gaugain says, and, I think, rightly, that 

 this is due to the greater thickness of liquid through which the 

 gas must now pass in order to get at the platinum — when the 

 platinum is partly exposed the film along the line of junction 

 being extremely thin. 



5. M. Gaugain made a cell in which the platinum plates 

 were movable, and determined, by the method of opposition, 

 the electromotive force when the plates were partly exposed; he 

 then lowered them until they were wholly immersed, and de- 

 termined the electromotive force immediately. In this experi- 

 ment the current was only allowed to flow for a few seconds. 

 He found that the two determinations were the same, and 

 concluded that the action of the battery depends entirely upon 

 dissolved gas. It is, however, open to any one to assert that 

 the platinums, when lowered, retained minute bubbles of gas 

 on their surface, and that thus there were still many points of 

 contact of liquid, gas, and platinum. 



6. M. Gaugain, following Dr. Schonbein, asserts that " the 

 oxygen serves simply to depolarize the positive wire," and 

 " that its function is that of sulphate of copper in Daniell's 

 cell " — in other words, that, were it not for the opposition 

 current developed by the freshly-deposited hydrogen, the cur- 

 rent could be kept up indefinitely without the presence of 

 oxygen. As I have before stated, I cannot conceive this state 

 of things. 



I. In order to show that some, at all events, of the current 

 in the gas-battery is due to dissolved gases, I made the follow- 

 ing experiments in the laboratory of Professor Carey Foster: — 

 A gas-couple with wholly submerged non-platinized platinum 

 plates was charged by electrolysis and short-circuited for a 

 week, after which the lengths of the columns of oxygen and 

 hydrogen were read off by means of a telescope on different 

 days, the couple being all the while short-circuited. A similar 

 couple, from which the platinum plates were removed after it 

 had been charged, was similarly treated. 



The barometer-reading was, of course, corrected for expan- 

 sion, for the column of liquid below the gas, and for aqueous 

 tension, the slight effect of sulphuric acid on the aqueous ten- 

 sion being neglected. A correction was applied for the curved 

 ends of the tubes, and the corrected lengths reduced to 0° C. 

 760 millims. 



Phil. Mag. S. 5. Vol. 5. No. 31. April 1878. T 



