THE ELEMENTS OF PLANT FOOD 



Large balloons are inflated with illuminating gas, which 

 contains much H. 



Hydrogen is odorless, colorless, and tasteless. Al- 

 though it is not found free in any considerable quanti- 

 ties, in compounds it is very abundant. It is pres- 

 ent in water (H 2 O), in all the oils, 

 and in all vegetable and animal sub- 

 stances. 



Preparation. Fit a bottle with 

 a stopper having two perforations, 

 one for the delivery tube and one 

 for a thistle tube to conduct liquids 

 to the bottom of the bottle. No 

 heat is required. In the bottom of 

 the bottle put a small quantity of 

 chips or filings of zinc. Pour diluted 

 hydrochloric acid in the thistle tube 

 till the zinc is covered with about 

 one half inch of it. As soon as action commences, 

 which may be noted as a kind of boiling and the 

 formation of many bubbles, the gas may be collected 

 over water. 



Reaction: Zn + 2 HC1 = ZnCl 2 + H 2 



Notes. As H is very light, it will escape when the jars are 

 placed in an upright position unless they are covered tight or left 

 inverted. Throw away the first jar of H obtained, as it may have 

 air mixed with it, which makes it explosive. The second jar may be 

 tested by placing a lighted match at the mouth of the jar. 



As H is lighter than air, it may be collected by upward displace- 

 ment. Take the delivery tube out of the water and thrust its open 

 end into a test tube held in an upright position with its mouth held 

 downward. The H will soon drive out the air and may be burned 

 as before. 



FIG. 5. Collecting Hy- 

 drogen by Upward 

 Displacement. 



