262 SPECIFICS FOR THE ALIMENTARY TRACT 



If applied to animal tissues (as in making leather) whicli is 

 chemically " gelatin tannate," the tissues tend to shrink together, 

 become harder and firmer, and less subject to putrefactive changes. 

 It is also more flexible than if simply dried. Strong solutions cause 

 a dense precipitate of the proteids, which prevent the further pene- 

 tration of the solution, v^hile vyeaker solutions are thought to pene- 

 trate more deeply and give a more thorough precipitation of the 

 proteids. 



If applied to raw surfaces, tannic acid precipitates the albumen 

 of the superficial cells and condenses the tissues just as explained 

 above. There is some belief that it also diminishes the sensibility 

 of the sensory nerves. It has a similar but stronger action when 

 applied to mucous membranes and at the same time dries up the 

 secretions by precipitating the proteids of the superficial cells. It 

 coagulates blood in a similar manner and serves as a styptic. 



When taken by the mouth, tannic acid or solutions of it have a 

 bitter astringent taste, cause a sense of dryness and roughness of the 

 mouth and interfere with the movements of the tongue. This action 

 is due to a coagulation of the proteids in the epithelial cells and 

 possibly to some shrinkage of the cells. The same feeling is pro- 

 duced in the throat and some discomfort and nausea, upon its reach- 

 ing the stomach, are sometimes shown. Upon reaching the stomach 

 it combines with any proteids there and precipitates them, but as 

 the stomach contents become acid as digestion, progresses, this com- 

 bination is broken up, since tannin does not combine with proteids 

 in an acid medium. Consequently the acid is free to act upon the 

 walls of the stomach and intestine. These it affects in a similar 

 manner to the mucosa higher up in the digestive tract. Moderate 

 doses are usually followed by firmer feces and some constipation, 

 while larger doses may sometimes cause diarrhea on account of the 

 irritation. 



Absorption and Elimination. Tannic acid is not absorbed as 

 such. It is decomposed into gallic and pyrogallic acids in the in- 

 testines, is then absorbed and finally eliminated mainly by the kid- 

 neys, as these products. A little is absorbed as sodium tannate but 

 the larger proportion undergoes complete oxidation. None of the 

 products into which it is decomposed have any astringent properties, 

 so the action of tannic acid must he purely local. 



Therapeutics, 1. Locally to check excessive secretion and im- 

 part tone to relaxed mucous membranes. In subacute and chronic 

 laryngitis, pharyngitis, swollen gums, etc. It is used in these con- 

 ditions in solutions of from 1 to 5 grains to the ounce as a spray or 

 wash. The glycerite may be of some service as an injection in 

 chronic vaginitis, etc. 



2i. Externally in oases of excessive secretions upon wounds, 

 ulcers, acute moist eczema, etc., and to toughen the skin. For this 



