98 AGRICULTURAL CHEMISTRY 



115. Uses. Sulfur is used in the preparation of sulfuric 

 acid, in the production of vulcanized rubber, in the 

 manufacture of matches and gunpowder, and for bleach- 

 ing and disinfecting purposes. A small amount in the 

 form of sulfates is necessary as plant food. 



Experiment ig. Properties of sulfur. Place 15 grams of 

 sulfur in a test-tube and heat slowly until it is a thin, amber-colored 

 liquid. As the heat increases, notice that it becomes darker until 

 black, and so thick and viscid that it cannot be poured from the 

 test-tube. Continue to apply heat until slightly lighter in color 

 and again a liquid. Then pour the sulfur into an evaporating dish 

 containing water, and, when cold, examine it and describe its proper- 

 ties. Examine the sulfur product or crystals left in the test-tube, 

 and compare with the original sulfur, using a lens for the purpose. 



Questions, (i) Are the crystals of sulfur formed by fusion like 

 those of the original powdered form ? (2) How is it possible for 

 sulfur to assume different physical forms ? (3) Is sulfur soluble in 

 water? (4) What is a sulfate ? Give the formula for one. (5) What 

 is a sulfite ? Give the formula for one. (6) What is a sulfid ? 



116. Sulfur Dioxid. When sulfur is burned either in 

 air or oxygen, SO 2 , a colorless, suffocating, non-combusti- 

 ble gas is produced. SO 2 combines with water, forming 

 H 2 SO 3 , sulfurous acid. Sulfur dioxid is used in bleach- 

 ing and for disinfecting purposes, as it is alike destruc- 

 tive to organic coloring-matter and to germ life. 



Experiment 20. Sulfur dioxid. Fill the deflagration spoon 

 half full of sulfur ; ignite, and then lower into a small cylinder con- 

 taining a piece of wet colored cloth and a piece of wet blue litmus 

 paper. As soon as the sulfur ceases to burn, remove the spoon and 

 cover the cylinder with a glass plate. 



Questions. ( I ) What reaction does the SO 2 give with the litmus 

 paper? (2) What effect does it have upon the cloth? (3) What 

 does the SO 2 form with H 2 O ? (4) Is SO 2 a heavy or light gas ? (5) 



