The 50 c.c. of neutralised distillate from the acidity determination are transferred to a screw-stoppered silver pressure flask, a few c.c. of cold, recently-boiled distilled water being used for rinsing. Twenty c.c. of decinormal soda, exactly measured, are then added, the stopper is screwed down, and the flask heated for two hours on a steam-bath. After cooling, the contents of the flask are transferred to a beaker and titrated with decinormal sulphuric acid.

If no pressure flasks are available, the solution may be boiled gently under a reflux condenser for an hour.

A "blank " experiment is made with the same quantity of alkali, using boiled distilled water in place of the alcohol. No. of c.c. iV/10-NaOH used up in the hydrolysis X 0.0088 x 2 = grams of ester, calculated as ethyl acetate, in 100 c.c. of the distillate. This result is then expressed in the customary form as noted for the volatile acid.