A YEAR IN SCIENCE 49 



magnet try to separate the iron from the sulphur. 

 What is the result? Place the mixture in a clean, 

 dry test tube. With the test tube holder, hold the tube 

 over the Bunsen flame until the contents begin to glow. 

 Remove it from the flame until the glow ceases, then 

 heat the tube again very strongly for a few minutes. 

 Remove the tube from the flame. When cool, break 

 the tube. Examine the contents. Test them with the 

 magnet. What changes have the substances under- 

 gone? The new substance is a chemical compound 

 called iron sulphide, resulting from the chemical union 

 of the elements, iron and sulphur. 



Another experiment to show chemical synthesis is 

 to grind together in a mortar, mercury and iodine 

 crystals. 



Exercise 26. Chemical Analysis. 



Object: The decomposition of compounds. 



Apparatus 



Mercuric oxide Pine splinter 



Hard glass test tube Bunsen burner 



Test tube holder 



Directions: Such characteristics as hardness, color, 

 form, etc., are known as the physical properties of a 

 substance. 



Note carefully the physical properties of mercuric 

 oxide. Place a very small amount of it in a test tube 

 and heat it very thoroughly. With the test tube in 

 the flame, insert a glowing pine splinter into the tube. 

 Continue heating the mercuric oxide. What change 



