1.1.1 ,Test Method A—,For petroleum products and lubricants soluble or nearly soluble in mixtures of toluene and propan-2-ol. It is applicable for the determination of acids whose dissociation constants in water are larger than 10^–,9, extremely weak acids whose dissociation constants are smaller than 10^–,9 do not interfere. Salts react if their hydrolysis constants are larger than 10^–,9. The range of acid numbers included in the precision statement is 0.1 ,mg/g KOH to 150 ,mg/g KOH.