158 GENERAL THERAPEUTICS FOR VETERINARIANS 



to check parenchymatous bleeding, and, empirically, in galactor- 

 rhoea, polyuria and nephritis. 



In their method of action they are very~ different. Some cause 

 a contraction and narrowing of the capillaries with consecutive 

 ansemia (metallic salts), thus overcoming inflammatory hypersemia 

 of the skin and mucous membranes and decreasing the secretions. 

 Others combine with the albumin, mucus, and gelatin-containing 

 substance of the secretions of the skin and mucous membranes 

 and form a solid precipitate and produce, like the caustics, a super- 

 ficial condensation and desiccation of the tissues, forming a kind 

 of scab or protective covering (tannin). A third group operates 

 by withdrawing water and shrinking (alcohol), and a fourth 

 group purely mechanically through compression (collodion). 

 Most of the astringents possess a disinfectant action and, in 

 the stronger concentrations, are caustics. (See the chapter on 

 caustics.) 



Drugs. — 1. The metallic astringents: alum, aluminum acetate, 

 ferric chloride solution, iron sulphate, lead acetate and nitrate, 

 silver nitrate, corrosive sublimate, zinc chloride and sulphate, 

 copper sulphate, zinc oxide, bismuth nitrate, subnitrate, subsali- 

 cylate and subgallate, aluminum hydroxide, calcium carbonate and 

 lime water. 



2. Tannic acid, tannoform and the tannin-containing vegetable 

 astringents: white oak bark, cinchona, rhubarb, nutgall, catechu 

 [replaced by gambir in U. S. P.], rhatany root, tormentilla root, 

 salvia, uva ursi, folia juglandis, coffee and roasted acorns. 



3. Alcohol and all alcoholic liquids (tinctura aloes, tinctura 

 myrrhae, tinctura iodi). 



4. Iodine, especially in combination with alcohol (iodine tinc- 

 ture) and glycerin. 



5. Tar, creolin, creosote and other related substances. 



6. Ethereal oils, balsams and resins (turpentine oil, turpentine, 

 Peru balsam). 



7. Glycerin and sodium chloride (withdrawal of water). 



8. Collodion (mechanical compression) and other pressure 

 agents. 



