HYDROGEN 4! 



with oxygen in the right proportion, as in the oxyhydro- 

 gen blowpipe, a high temperature is secured. 



42. Importance. Hydrogen is one of the essential ele- 

 ments for the formation of compounds present in plant 

 and animal tissues, but because of its extreme lightness 

 it never makes up a large portion by weight of a mate- 

 rial. As a free element, it takes no part in life processes, 

 but when combined with water, and in other forms, as in 

 food materials where it is united with carbon and oxy- 

 gen, it forms an essential part of compounds which are 

 of much importance for animal and plant life. 



Problem i. How many pounds of H will 100 pounds of Zn 

 liberate when it is acted upon by H 2 SO 4 ? 



Problem 2. How much ZnCl 2 is formed when 100 pounds of 

 Zn are acted upon by HC1 ? 



