234 



ELEMENTARY GENERAL SCIENCE 



CHAP. 



tube from a flask containing water previously boiled to drive 

 off the dissolved air. Heat the iron filings well, and boil the 

 water in the flask so that the steam passes over the heated 

 iron and then into the water, where it condenses. Now place 

 over the end A an inverted test-tube of water, and note that 

 the steam is not completely condensed, but that minute 

 bubbles ascend to the top of the test-tube. When you have so 

 obtained a sufficient quantity of gas (half a small test-tube), 

 first remove C from the flask of water, then stop the boiling. 

 Close the end of the test-tube with your thumb, and holding a 



Hydrogen 



FIG. 118. Action of Steam on Heated Iron. 



lighted match to the mouth, open the tube. Observe that the 

 gas burns. Examine the iron filings in the tube CA, and see 

 that a quantity of rust has been formed. 



Action of Sodium upon Water. We see, therefore, that from 

 the steam and iron we obtain iron rust, that is, iron oxide, and 

 an inflammable gas. We must investigate this further, as it 

 appears to show that the water contains this inflammable gas and 

 oxygen. We must find something which has a more powerful 

 action on oxygen than the iron. Such a substance is the metal 

 sodium, which we have before used. 



EXPT. 235. Place a small piece of sodium in water in an 

 evaporating basin, and observe the action. Feel the water left 



