Dr. Beetz o?i the Electromotive Force of Gases. 93 



of coke were placed, in a short time they gave off an odour of 

 sulphuretted hydrogen. Those experiments in which this 

 occurred always yielded very small results, and were of course 

 rejected. In those detailed below, no sources of error were 

 remarked. They show that the relation of the electromotive 

 forces, when different gases are used, is exactly the same as 

 with platinum. I have therefore divided the mean electro- 

 motive force of an oxyhydrogen platinum battery by that of 

 an oxyhydrogen carbon battery, and divided the forces of the 

 other platinum batteries by the quotient c. In this manner 

 the last column denoted by " calculated " was obtained. The 

 resistances were determined by separate experiments. 



The factor c evidently depends upon the condensation which 

 the gases experience at the surface of the solid conductor, and 

 by which the coating of the metal with the gases is rendered 

 more perfect. Hence this method might be used for deter- 

 mining the relative condensing force of different bodies, if the 

 absolute magnitudes of the electromotive forces in most mat- 

 ters were not too small. The coefficient 0*4687 cannot cer- 

 tainly be considered as applying to carbon generally. Other 

 kinds of carbon may differ very greatly. 



I obtained the following values in the case of gas batteries 

 with chemically pure plates of silver, which were silvered gal- 

 vanically :— ,^ ^^^a ^ ^a^dviBaf^fl laioamheqx: 



.»ea.q,ixi.ioy«iw\»R«K8'liobn935oH r 



