AND PHARMACOPOLIA. 429 



good grooming. Astringents must be employed with much 

 caution in diarrhoea, especially in horses. In these animals it is 

 generally occasioned by bad hay or oats, and may be corrected 

 by altering the diet. In horses of weak constitutions it may be 

 brought on by drinking too freely of very cold water. In such 

 cases the remedy is obvious. In general, the diarrhoea of horses 

 may be stopped by attention to these circumstances, especially if 

 assisted by gruel made of arrow-root or wheat flour ; and it is 

 only after this has failed that astringents should be resorted to. 

 The diarrhoea of cattle is of a more formidable nature, and ge- 

 nerally proves incurable, unless the animal is sheltered from the 

 weather, and fed partly or wholly on Avholesome nutritious food. 

 The astringents most useful in the diarrhoea of cattle are catechu, 

 kino, oak-bark, pomegranate-bark, with aromatlcs and opium, 

 joined with a nutritious diet. Diuretics have been prescribed, 

 such as turpentine, which probably may be advantageously joined 

 with tonics or cordials. Astringents are often required as ex- 

 ternal applications, as in grease, and troublesome sores about the 

 heels or other parts, or thrushes of the frog. For such purposes 

 finely-powdered alum, either alone or mixed with pipe-clay, or 

 bole-armenlc, may be used ; or sulphate of zinc or copper, finely 

 powdered and mixed with pipe-clay, chalk, or bole, or dissolved 

 in water or vinegar. These astringents may be occasionally 

 mixed Avith lard, or wax-ointment, in which case they should be re- 

 duced to a very fine powder. Acetate of lead (sugar of lead) is 

 an excellent astringent for external use, whether dissolved in 

 water, or diluted with vinegar or spirit, and employed as a lotion, 

 or with lard or other unctuous substances, and used as an ointment. 

 (See Acetate of Lead.) Though the sulphate of copper (blue 

 vitriol) Is named here as an astringent, it may be rather consi- 

 dered an escharotic or mild caustic, when used alone externally ; 

 but it may be so weakened by dilution as to become an astringent, 

 and when sufficiently weakened with water, may be applied even 

 to the eyes. (See Copper.) Sulphate of zinc (white vitriol or 

 copperas) is also an useful astringent when rendered mild by 

 mixture with water or unctuous substances, such as lard : but 

 alum is still milder, and may be used as an astringent in powder. 

 Sidphate of iron (green copperas or vitriol) is a powerful astrin- 

 gent, and is sometimes used internally as a tonic. The dose, 

 from on*^ to two or three drachms. It is seldom emj^loyed ex- 

 ternally, and then in solution only. From the foregoing obser- 

 vations it will be seen that the distinction between tonics and 

 astringents is not very clearly marked. The mode of operation 

 of astringents on the living body has been erroneously supposed 

 to be similar to that by which dead animal fibres are constrlnged 

 and condensed. That property of vegetables which is termed 

 astringency, as it relates to dead animal matter, results from a 



