This section is from the book "Alcohol, Its Production, Properties, Chemistry, And Industrial Applications", by Charles Simmonds. Also available from Amazon: Alcohol: Its Production, Properties, Chemistry, And Industrial Applications.
Evaporate 100 c.c. of the cider down to about 10 c.c, and add 60 c.c. of alcohol (90 per cent.) to precipitate the pectic matters. Allow the latter to settle, decant off the liquid, redissolve the precipitate with a little water, and repeat the treatment with alcohol. Filter on a tared filter, dry carefully, raising the temperature gradually to 100°, and weigh. Incinerate the filter and its contents, and deduct the weight of the ash from the first result to obtain the weight of pectins.