Lead salts are poisonous.
Chemicals and Solutions:
0.1 M lead nitrate solution
lead testing solution: sodium sulfide aq.
Previously tested lead containing dishes
Lead testing video
Combine lead nitrate solution and sodium sulfide solution in a cylinder. A black precipitate of lead sulfide forms.
Show about 10 min. of the videotape about the hazards of lead in glazes.
Show the dishes that have tested positive for lead. (Vinegar was placed in each vessel for 24 hours. Then the vinegar was tested with sodium sulfide. In each case a black precipitate of lead sulfide was obtained.)
Discussion:Lead has been a common component in the glazing process of ceramics for centuries. When properly fired no hazard is presented; but if improperly fired toxic lead can be leached out by acidic foods or beverages. If this lead is ingested it can have severe health effects including damage to the nervous system, kidneys, liver, reproductive systems, cardiovascular system, immunological system, and gastrointestinal system. Even at low levels lead may cause learning and behavioral disorders in children and affect their growth.