stock solution

Put this in your stock solution bottle, and keep it in a dark place for twenty-four hours.

Add then not more than a teaspoonful at a time caustic soda solution until the Stock Solution answers the glass test.

Add a small cupful of the Stock Solution, stir carefully without splashing.

If the Stock Solution is greenish white and turbid, undissolved indigo white is present.

Pour off from the sediment and keep the liquid as a stock solution in a tight barrel or keg.