﻿44 Prof. E. Edlund's Experimental Proof that 



obtained. Thereupon the same experiment was made with a. 

 battery of a few Bunsen's elements, after so great a resistance 

 had been interposed in the conduction that the deflection of the 

 galvanometer was about as great as that produced by the voltaic- 

 spark current. But just as little with this current was there a 

 certain proof of the decomposition of water. The currents in 

 both cases were too feeble to produce distinct ascending gas- 

 bubbles ; the gas which is produced by so feeble a current is so 

 small in quantity that it is partially retained by the platinum 

 disks and partially absorbed by the liquid. It was next attempted 

 to ascertain whether the voltaic-spark current was sufficiently 

 strong to produce a polarization in the platinum disks. With this 

 view a glass vessel was filled with water containing sulphuric acid, 

 in which were placed two pieces of platinum-foil, one connected 

 with i and the other with k. While the electrophorus disk was 

 turned, the conducting-wires of the galvanometer were separated 

 from i and k, but by means of a commutator could be again joined 

 with these points as soon as the comb a was connected by means 

 of a brass rod with the comb b and therefore all flow of electri- 

 city to the polarization-vessel ceased. If the discharge was now 

 allowed to pass through the polarization-vessel for a given time 

 while the knobs g and / were so far apart that no sparks ensued 

 between them, a feeble polarization-current was always obtained 

 when the galvanometer was connected with i and k. If, on the 

 contrary, sparks passed between / and g while the machine was 

 at work, after connecting the galvanometer-wires with i and k, a 

 polarization- current was obtained which was much stronger than 

 before. The deflection took place towards the proper side, and 

 the current gradually diminished till it entirely ceased. If 

 the machine was for some time in activity, the polarization-cur- 

 rent was so powerful that the scale of the telescope was inad- 

 equate to measure the first deflection. 



4. The knobs used in the spark-apparatus were of iron, brass, 

 and tin, and all of the same magnitude, namely 17 millims. dia- 

 meter. The position of equilibrium of the needle was determined 

 by observing points on the scale where the needle turned, and 

 taking the mean of two observations belonging to the same os- 

 cillation. For a single oscillation the needle required about 

 eleven seconds. The electrophorus disk was turned with as 

 uniform a velocity as possible. As the disk, when it once began 

 to move, could not at once be brought to rest, the machine, when 

 it was necessary to do so, was rendered inactive by connecting the 

 two combs by a metal rod. The following are a few of the 

 observations made : — 



