Add 5 cc. of neutral chloroform and 1 cc. of erythrosine indicator to 50
or 100 cc. of the sample in a 250 cc. clear glass-stoppered bottle. If
the chloroform becomes rose colored on shaking, hydroxide, bicarbonate,
or normal carbonate is present. Add N/50 sulfuric acid from a burette
until the chloroform becomes colorless. A white surface behind the
bottle facilitates detection of a trace of color as the end-point is
approached. The calculation is the same as with phenolphthalein
alkalinity.