1897.] 



Newly Prepared Gases. 



367 



other gas by diffusion. Also, by continuing the stream of hy- 

 drogen into P, the density of the charge in P increases, so that 

 diffusion not only affords a method of removing the charge from 

 a gas, but also gives us a means of increasing the electrification 

 per unit volume. 



Experiments with hydrochloric acid. 



(24) When gases are given off by electrolysis both the quantity 

 and sign of the electricity which they carry are affected by 

 various causes. These changes which the charge undergoes are 

 well illustrated by a series of experiments which were performed 

 with a 20°/ solution of hydrochloric acid. 



The form of the apparatus used to generate hydrogen and 

 chlorine by electrolysis from hydrochloric acid is shown in 

 figure 6. It consists of two glass bulbs, joined together, from 



Fig. 6. 



each of which project two tubes S 1} T x and S 2 , T 2 . The tubes 

 S 1 and S 2 acted as delivery tubes for the gases, which collected in 

 the spaces immediately underneath them. The electrodes, E 1 

 and E 2 , consisted of carbon sticks which fitted into the tubes T t 

 and T 2 ; indiarubber tubing projecting over the ends of T 1 and T. 2 

 prevented the apparatus from leaking when the bulbs were filled 

 with a liquid. The carbon sticks had a thin layer of copper 

 deposited on the ends A, so as to make good contact with the 

 mercury in the cups C u G 2 . These cups acted as terminals to 

 which the leads, from the cells supplying the current, could be 

 joined. The current through the electrolyte was given by an 

 ammeter in the circuit, and was easily adjusted to any required 

 value by means of a variable resistance. 



