PHYSIOLOGY. 



frequent taking in of liquids in small quantity, and an inward 

 thirst, which requires the copious deglutition of liquids. The 

 dryness of the fauces alone will occasion thirst. The breathing 

 an air which is more dry or filled with dust, will immediately 

 occasion an absorption of the fluids and a dryness of the fau- 

 ces. The ' heat of these parts 1 accompanies a heat of the body 

 in general, it operates partly by the sensation of heat, and 

 partly by abstracting the fluids. Thirst is further increased by 

 acrimony, that requires drink to allay the sensation which is 

 raised, and by the putrescency or viscidity of the contents of 

 the stomach. How the effect of the latter is produced, it is 

 difficult to say, but I give it as a fact which we know, that veal, 

 lamb, and chicken, produce thirst more readily than beef, mut- 

 ton, or fowl. Thirst arises more particularly from all increased 

 evacuations. Thus, sweating is certainly attended with thirst, 

 which may perhaps in part be owing to the heat necessarily 

 accompanying it, but in part also probably to the evacuation, 

 which, by diminishing the secretion of the fauces, occasions a 

 dryness there. But as this instance might be ambiguous, we 

 mention diarrhoea and diabetes, diseases which are strongly mark- 

 ed with thirst ; and, in like manner, an evacuation which is not 

 constant in women, that of giving suck, when they drink more 

 than at other times. It is not necessary that these evacuations 

 should be considerable to produce this dryness ; they are no 

 sooner increased than the thirst arises. Such is the connexion 

 established, that the deviations of the system should be obvi- 

 ated and corrected ; and therefore nature has directed thirst to 

 accompany all increased evacuations of the more liquid parts of 

 the blood." 



CCV. These appetites determine men to take in a great 

 variety of solid and liquid matters, directed by instinctive 

 likings and disgusts, in some instances corrected by experi- 

 ence. 



CCVI. Of the matters chosen, it appears that some of them 

 are suited to supply the matters of the fluids or solids of the 

 body, and, therefore, properly named Aliment ; while others of 

 them are suited only to improve the relish of aliment, or to 

 obviate some deviations ready to happen in the business of di- 

 gestion, and these we name CONDIMENTS. 



