Treat 10 grams of the sample, prepared as directed under 4, with 75 cc.
of 80-percent alcohol by volume in an Erlenmeyer flask, stopper, and
allow to stand 16 hours, shaking occasionally. Filter and transfer an
aliquot of the filtrate (25 cc. in the case of green coffee, 10 cc. in
the case of roasted coffee) to a beaker, dilute to about 100 cc. with
water and titrate with N/10 alkali, using phenolphthalein as an
indicator. Express the result as the number of cc. of N/10 alkali
required to neutralize the acidity of 100 grams of the sample.