54 



AGRICULTURAL CHEMISTRY 



Fig. 26. Obtaining unburned gas 

 from candle. 



hydrogen of a gas or candle forms H 2 O during combus- 

 tion, and can be collected by passing the products of 



combustion through suitable 

 absorbents. If a dry test-tube 

 is held above the flame, a little 

 moisture will collect on the 

 sides of the test-tube. 



57. Compounds of Carbon. 

 Chemically, carbon forms a 

 very large number of com- 

 pounds, more, in fact, than 

 any other element. The car- 

 bon compounds present in 

 plant and animal tissues are 

 studied in a separate division 

 of chemistry known as organic chemistry, while those 

 compounds of carbon which are in com- 

 bination with the mineral elements, as 

 calcium, sodium, and potassium, are 

 studied in inorganic chemistry. No well- 

 defined boundary line, however, can be 

 established between these two divisions 

 of chemistry. 



58. Importance of Carbon. The com- 

 pounds found in plant and animal bodies 

 contain carbon in larger amounts than 

 any other element ; consequently the 

 carbon compounds take a very import- 

 ant part in animal and plant growth. 



Carbon is the element essential for the production of heat 



Fig. 27. Combus- 

 tion of gas from 

 candle. 



