Dr. Beetz on the Electromotive Force of Gases. 85 



and a quarter of an inch in breadth, were therefore cemented 

 into corks before platinization, and after the phites had been 

 connected in the platinum solution, they were inserted into 

 tubes about five inches in length ; the tubes were then filled 

 with water; this kept boiling for several minutes, and then 

 replaced by the conducting fluid (dilute sulphuric acid of 

 1 per cent.). This was also heated to ebullition, and the 

 open end of the tube then immersed in a vessel, which also 

 contained some of the boiled conducting fluid. The gas 

 under experiment, in its utmost state of purity, was then ad- 

 mitted into the tube in such a manner that about one-third 

 of the plate dipped into the liquid. To connect two tubes so 

 as to form a circuit, an inverted U-shaped tube, filled with the 

 conducting liquid and connected at each end with a bladder, 

 was dipped into the two vessels which contained the tubes ; 

 by this arrangement, difflision of the gases through the liquid 

 was better prevented than when both the tubes were placed in 

 the same vessel. If, in measuring, the proportion of a to ^ in 

 the first experiments was found to be too defective, so that the 

 gas-circuit was traversed by a perceptible current, it was first 

 again tried until the galvanometer G remained at ; the gas 

 battery was then taken to pieces, and the whole process of 

 filling it commenced anew. In the second measurement we 

 commence with test experiments, which are not so far removed 

 from the truth as to be capable of altering the battery percep- 

 tibly. The results last obtained only are given. After a little 

 practice, we are generally enabled to avoid making too great 

 mistakes in the position of the binding-screws, particularly 

 when we have obtained an insight into the law which is de- 

 ducible from the experiments. 



* The tubes filled as in series III. were retained. 



