INVISIBLE INK
2 tbsp. cobalt chloride
2 tsp. white dextrin
3 1/2 tbsp. glycerine
Combine all ingredients in small saucepan. Cook over low heat until well blended, stirring constantly. Cool completely. Store in tightly covered clean jar. Ink is pale pink on colored paper. Expose to heat or light bulb and writing turns blue. Note: Cobalt chloride and dextrin may be purchased from a chemical supply house and glycerine from a drug store.