618 VETERINARY MATERIA MEDICA. 



also, in an intense degree, is a powerful antispasmodic, 

 for which reason it is applied in tetanus. 



Aperients. — See Laxatives. 



Arsenic, oxide {Arsenicum oxydum) . This powerful mine- 

 ral is somewhat uncertain in its action, and not always 

 safe : were it not for this, it might- be called a good 

 tonic, in doses of five to ten grains daily, in a very 

 fine powder : more has been given ; but it sometimes 

 appears to remain innocuous until the constitution is 

 fully saturated with it ; and then commences its noxious 

 effects suddenly and irreparably : this destroys much of 

 its usefulness, and makes it necessary to exhibit it with 

 great caution : nor should it ever be given on an empty 

 stomach. The best form in which it can be adminis- 

 tered is, as the liquor arsenicalis, made by boiling its own 

 weight of potash with arsenic and water (one ounce of 

 water to every four grains of arsenic), in some glass 

 vessel. It has the power of staying the progress of 

 glanders ; and it ultimately cures farcy when watched and 

 continued : it also appears to have some vermifuge pro- 

 perties ; and it certainly retards the march of the rabid 

 disease, but is not ultimately successful. 



Astringents. — These are supposed to act on the living 

 fibres by producing increased contraction in them, in 

 which point of view they form a very numerous and im- 

 portant class ; but in a more limited sense, they are 

 considered as substances that restrain immoderate fluxes, 

 ^s of the intestines and kidneys. Those that act by 

 constringing the divided ends of bloodvessels are called 

 styi")tics. Opium, chalk, alum, starch, and catechu, act 

 favourably in restraining intestinal fluxes. Catechu, 

 alum, and acetate of lead, operate as astringents on the 

 urinary passages. 



Balls. — There are some circumstances, in the preparation 

 of this form of medicines, not in general sufficiently 

 attended to by veterinarians. Substances that are vola- 

 tile do not keep well in balls, and therefore should only 

 be made when used. The same caution is also requisite 

 with such as liquefy by the absorption of air. All hard 

 substances entering into balls should be finely powdered. 



