HYDROGEN 



155 



a retort which is kept cool by a stream of water flowing in at the tubule 

 and out at the end of the neck (Fig. 107). Observe the formation, on the 



FROM WATER SUPPLY 



FIG. 107. The water formed when hydrogen burns in the air can be collected 

 and examined. 



outside of the retort, of a clear liquid which collects and drops into a beaker 

 placed to receive it. By this means sufficient of the liquid can be obtained 

 to identify it, especially if several students add together the liquids formed 

 in their experiments. 



(6) Take the density, freezing 

 point (a mixture of sodium 

 sulphate and hydrochloric acid 

 forms a convenient freezing 

 mixture), and boiling point of 

 the liquid formed by burning 

 hydrogen. You will find these 

 are 1, C., and 100 C. respec- 

 tively, and these results are 

 sufficient to enable it to be 

 stated that the liquid is identi- 

 cal with pure water. 



ii. Analysis of water. This 

 may be done by means of an 

 electric battery for generating 

 the electric current, and a volta- 

 meter. The latter is most 

 simply made by closing the 

 bottom of a funnel by means 

 of a tightly fitting cork through 

 which pass two platinum wires 

 with small plates of platinum 

 attached to the ends remaining FlGt 10 g A voltameter in which water can be 

 in the funnel (Fig. 108). Over analysed by the electric current. 



