Possible Clues:

• Dissolved substance
• Salt in salt water, e.g
• Sugar in coffee, e.g.
• A dissolved substance
• Alka-Seltzer in water, e.g
• It's dissolved into a solvent
• Substance in a chemistry experiment
• Sugar in tea, e.g.
• Alka Seltzer in water, e.g.
• Very good protective material is free