This section is from the book "The Human Body: An Elementary Text-Book Of Anatomy, Physiology, And Hygiene", by H. Newell Martin. Also available from Amazon: The Human Body.
The Chyme contains, after an ordinary meal, a considerable quantity of peptones, which are in great part gradually absorbed into the blood and lymphatic vessels of the gastric mucous membrane and carried off, along with other dissolved and dialyzable bodies—for example, salts and sugar. After the food has remained in the stomach some time (one and a half to two hours) the chyme begins to be passed on into the intestine in successive portions. The pyloric sphincter relaxes at intervals, and the rest of the stomach, contracting at the same moment, injects a quantity of chyme into the duodenum; this is repeated frequently, the larger undigested fragments being at first unable to pass the orifice. At the end of three or four hours after an ordinary meal the stomach is quite emptied, the pyloric sphincter finally relaxing to such an extent as to allow any larger indigestible masses, which the gastric juice has not broken down, to be squeezed into the intestine.*