Emily went into her bedroom and got out her Chemistry set - she thought it would be fun to try adding some chemicals from there to the water. She checked the instruction booklet to make sure that none of them would be dangerous.
She decided to try a lovely blue crystal called COPPER SULPHATE. She stirred a spoonful into her water and observed that after a minute all the crystals had disappeared to leave a pretty blue liquid.
She filtered the blue liquid which passed through the filter paper leaving nothing behind.
What happened to the copper sulphate crystals?