146 



SMITH'S INTERMEDIATE CHEMISTRY 



Composition of Hydrogen Chloride. Now that we are 

 familiar with the properties of chlorine, as well as with those 

 of hydrogen, we may return to the 

 question of the proportion by vol- 

 ume in which they are produced by 

 decomposition of hydrogen chloride. 

 When we electrolyze hydrochloric acid 

 in the apparatus shown in Fig. 27 

 (p. 54), we find that the chlorine dis- 

 solves to a large extent in the liquid, 

 and its true volume as gas is not easily 

 ascertained. The apparatus (Brown- 

 lee's) in Fig. 50 avoids the difficulty 

 by enabling us to saturate the liquid 

 with chlorine before observing the col- 

 lected gases. The volumes of the two 

 gases are found to be equal. 



A simpler apparatus (Fig. 51) may be 

 used to show the same fact. The gases 

 are generated, by electrolysis, in the test- 

 tube, pass through the straight tube, 

 driving the air before them, and finally bubble through sodium hy- 



FIG. 51 



droxide solution. The whole apparatus must be covered with a 

 dark cloth to exclude light, and handled in diffused light. In fifteen 



