Dilute the filtrate from the determination of insoluble matter to 1,000
cc. and thoroughly mix. Titrate 25 cc. of this dilution with N/10
hydrochloric acid in presence of methyl orange indicator. The percentage
of available alkali, expressed as sodium carbonate (Na_{2}CO_{3}), is
equal to 4 times the number of cubic centimeters of hydrochloric acid
used.