Add 4 drops of lacmoid indicator to 50 or 100 cc. of the sample in a
porcelain casserole or an Erlenmeyer flask. Add N/50 sulfuric acid from
a burette until within 1 or 2 cc. of the amount necessary for
neutralization has been added. Heat the solution until bubbles of steam
begin to break at the surface. Remove the dish from the source of heat
and continue the titration until a drop of the acid striking the surface
of the liquid and sinking to the bottom of the vessel produces no change
in the uniform reddish or purple color of the solution. The calculation
is the same as for phenolphthalein alkalinity.