Page:Mrs Beeton's Book of Household Management.djvu/166

124 saliva and digestive juices, weakening their activity. Too long fasting turns the natural alkalinity of the saliva to acidity, resulting in heartburn. Coffee and tea retard digestion. They should not be partaken of at a meal when meat is eaten to any extent. In the aged, however, good tea is undoubtedly beneficial by reducing tissue waste. Wines and light beers in moderation gently stimulate digestion, but strong beers and alcohol greatly prolong the process.

Under normal conditions, it is well that the digestive process should not be prolonged beyond four to four-and-a-half hours. For invalids and persons with "weak stomachs," the time allowed should be much less. It is, therefore, necessary to study the table of digestibility, which has been compiled from the result of repeated experiments by a number of doctors. It must, of course, be remembered that with invalids, the weak, children, and aged persons, digestion is prolonged beyond the normal indicated below.