236 ELEMENTARY GENERAL SCIENCE CHAP. 



Preparation and Properties of Hydrogen. From water 

 and sodium we have therefore obtained an inflammable gas, 

 lighter than air, which does not support combustion, while there 

 is also formed a solution which behaves like the solution of 

 sodium oxide. The most natural inference is that the water 

 contains this inflammable gas which we call hydrogen, and 

 oxygen. Before proceeding to verify this, which we must do, 

 it will be well to examine more carefully the properties of the 

 inflammable gas, and to do this we should collect it in greater 

 quantity than hitherto. For this purpose we must act upon a 

 metal with a dilute acid instead of water. 



EXPT. 239. Select a flask and fit it up as is shown in 

 Fig. 120. Be very careful that the stopper and the tubes 



FIG. 120. Preparation of Bottles of Hydrogen. 



respectively fit very closely. Into the flask put enough granu- 

 lated zinc to cover the bottom. Pour some water upon the 

 zinc. Arrange the delivery tube in the trough as you did 

 when you were making oxygen. Pour a little sulphuric acid 

 down the thistle-headed acid funnel, and be quite sure that 

 the end of the funnel dips beneath the liquid in the flask. 

 Do not collect . bottles of the gas until you are sure pure 

 hydrogen is being given off, which you can find out in this 

 way. Fill a test-tube with water and invert over the end of 

 the delivery tube. When it is full of gas, still holding it 

 upside down, take it to a flame (which should not be near the 

 flask you are using) notice that there is a slight explosion. 

 Continue this until the hydrogen burns quietly down the 

 test-tube. When this happens you may proceed to nil one 



