ISO 456:1973

The determination may be carried out in two different ways by the ethanol method or the barium chloride method. In the first case the soap is dissolved in neutralized ethanol, and the free caustic alkali is titrated with an ewthanol solution of hydrochloric acid. The second way includes precipitating of soap and carbonate with barium chloride and determining of the residual alkalinity of the solution, representing the alkalinity of the free potassium hydroxide.