LIQUIDS. 625 



lips; and the atmospheric pressure on the surface of the fluid in the 

 vessel forces it into the mouth, to replace the air that has been drawn 

 from the mouth by the dilatation of the thorax. In sucking, the mouth 

 may be compared to an ordinary syringe; the nozzle of which is re- 

 presented by the lips; the body by the cheeks, palate, &c., and the 

 piston by the tongue. To put this in action, the lips are accurately 

 adjusted around the body from which the liquid has to be extracted. 

 The tongue is likewise applied, contracts, and is carried backwards; 

 so that an approach to a vacuum is formed between its upper surface 

 and the palate. The fluid, no longer compressed equally by the atmo- 

 sphere, is displaced, and enters the mouth. 



As neither mastication nor insalivation is required in the case of 

 liquids, they do not remain long in the mouth, unless their temperature 

 is too elevated to admit of their being passed down into the stomach 

 immediately, or they are of so luscious a character, that their prolonged 

 application to the organ of taste affords pleasure. Their deglutition is 

 effected by the same mechanism as that of solids ; and, as they yield 

 readily to the slightest pressure, with less difficulty. Their accumula- 

 tion in the stomach takes place in much the same manner. They arrive 

 by successive mouthfuls; and, as they collect, the thirst disappears 

 with all its local and general attendants. If, however, the organ be 

 over-distended a disposition to vomiting is induced. 



The changes, which liquids undergo in the stomach, are of different 

 kinds. All acquire the temperature of that viscus, and become mixed 

 with the secretions from its internal surface, as well as from that of 

 the supra-diaphragmatic portion cf the digestive tube. Some, however, 

 undergo the operation of chymification ; others not. To the latter 

 class belong, water, weak alcoholic drinks, the vegetable acids, &c. 

 Water experiences the admixture already mentioned ; becomes turbid, 

 and gradually disappears, without undergoing any transformation. 

 Part passes into the small intestine; the other is directly absorbed. 

 When any strong alcoholic liquor is taken, the effect is different. Its 

 stimulation causes the stomach to contract, and augments the secre- 

 tion from the mucous membrane ; whilst, at the same time, it coagu- 

 lates all the albuminous and mucous portions; mixes with the watery 

 part of the mucous and salivary fluids, and rapidly disappears by ab- 

 sorption ; hence, the speedy supervention of inebriety, or death, after 

 a large quantity of alcohol has been taken into the stomach. The 

 substances, that have been coagulated by the action of the alcohol, are 

 afterwards digested like solid food. We can thus understand the good 

 effects of a small quantity of alcohol, taken after a substance difficult 

 of digestion, a custom which has existed from high antiquity, and has 

 physiology in its favour. It is, in such cases, to use the language of 

 the eccentric Kitchener, 1 a good "peristaltic persuader." 



Oil remains longer in the stomach than any other liquid, experiences 

 little change there, but passes into the small intestine, where it forms 

 an emulsion and enters the veins and chyliferous vessels. Milk, as is 



1 Directions for Invigorating and Prolonging Life ; or the Invalid's Oracle, &c., Amer. 

 edit., from the 6th London, by T. S. Barrett, New York, 1831. 



VOL. i. 40 



