48 



LABOEATOEY MANUAL 



a glass stirring rod, stir until the salt is all dissolved. 



Filter and evaporate the filtrate (the liquid which 



passed through the filter) to dryness, using the evapo- 

 rating dish. What is the 

 substance left in the 

 evaporating dish? To de- 

 termine this, taste it. 

 With the magnet, test the 

 substance left on the filter 

 paper. What is it ? In mix- 

 ing together iron filings 

 and salt were the prop- 

 erties of either changed? 

 If two or more sub- 



stances are placed to- 



Fig - 18 - gether, and each retains 



its original properties, the resulting substance is called 



a mechanical mixture. 



Exercise 25. Chemical Synthesis. 



Object: To determine the formation of compounds. 



Apparatus 



Test tube holder 

 Bunsen burner 

 Mortar and pestle 



Iron filings 

 Flowers of sulphur 

 Test tube 

 Magnet 



Directions: Note carefully the nature of the ele- 

 ments, iron filings and sulphur. Grind together in a 

 mortar 2 grams of sulphur and 2 grams of iron filings. 

 The grinding is to be done very thoroughly. With a 



