88 Dr. Beetz on the Electromotive Force of Gases. 



Sufficient agreement of the experiments with this law might 

 be obtained if the means of the experiments made with the 

 same matters were taken, and these were considered as the 

 true electromotive forces; but, properly speaking, only those 

 experiments belonging to one and the same series ought to 

 be compared with each other ; because in them, even an alte- 

 ration in the composition of a gas, an impurity acquired by it 

 during the filling of the tubes, &c. cannot exert any influence; 

 those alterations only would become perceptible which the 

 gas might have experienced in making the measurements 

 themselves. In the following tables, the sums of the electro- 

 motive forces of different circuits are compared with the elec- 

 tromotive forces which were observed between the outermost 

 members of these circuits. 



