Nickel salts are particularly toxic
Chemicals and Solutions:
Ferric Ammonium sulfate
Nickel ammonium sulfate
3.0 liters of Commercial Silicate Solution
Crystals are dropped into the silicate solution. The metal ions react with the sodium silicate to form a thin membrane of insoluble metal silicate. Water penetrates the membrane by osmosis, causing it to expand and burst. A new membrane then forms and the process repeats causing a column of colored metal silicate to form.