8 M. W. Beetz on the Excitation of Electricity 



tromotive forces : — 



1-32 



1-33 



1-28 



1-30 



1-30 



1-29 



1-27 



1-27 



1-38 



1-37 



1-37 



1-32 



Mean ... Zn | C=1'31D. 



For each series of experiments fresh carbons had to be em- 

 ployed, as the carbons, altered by the various actions which 

 they had undergone, could not be again brought into their 

 initial condition. Oxygen or hydrogen, led into the tubes 

 enclosing the carbons, produced not the slightest result ; the 

 electromotive force of the combination remained quite unal- 

 tered = Zn j C. The behaviour of carbonic oxide and ethy- 

 lene gas was just as indifferent. These results do not accord 

 with my earlier experiences, according to which the gases 

 mentioned acted as electromotors on Bunsen's carbon also, and 

 by which I was induced to assume that the electromotive 

 forces of carbon batteries composed of different metal (or car- 

 bon) plates, but of the same gases, stood in a definite relation, 

 dependent on the condensing force exerted by the metals upon 

 the gases. The carbons with which I worked thirty years 

 since were very porous — battery carbons prepared from coke 

 and coal ; and at that time I said that the coefficient of con- 

 densation which I found for my carbons was certainly not to 

 be regarded as holding good generally, but that other carbons 

 might behave differently. Thus, with those now used such 

 proportionality is altogether out of the question ; the gases 

 employed cannot have undergone any condensation upon the 

 carbon. In order to test this rather unlikely fact more mi- 

 nutely, I cut out of such retort-carbon two regular-shaped pieces, 

 each of 0'5 x 0*5 centim. cross section and 1 centim. length, 

 the solid content of each being thus 0'25 cub. centim. These 

 pieces were strongly heated and then introduced into ammonia 

 gas which was enclosed in measuring-tubes over mercury. 

 After the old temperature was fully restored, the volume of the 

 ammonia gas had increased by a minute quantity which could 

 not be precisely determined with the altered form of the me- 

 niscus. Had the increase amounted to 0*25 cub. centim., it 

 would have been a proof that in fact no gas was absorbed ; 

 still the experiments showed that the retort-carbon had taken 

 up as good as none of even this gas, which is briskly absorbed 

 by the other sorts of carbon. 



Very different was the behaviour of the carbon to chlorine. 

 This gas was conducted into the tube of the element until it 

 was no longer completely absorbed ; then the connexion of the 

 conducting liquid with the zinc-cell was restored; when the 



