MEDICINES. 387 



then well rubbing in the ointment, for at least ten minutes— and afterwards, 

 and what is of the greatest consequence of all, plastering a little more of the 

 ointment lio-htly over the part, and leaving it. As soon as the vesicles have 

 perfectly ri^en, which will be in twenty or twenty-four hours, the torture 

 of the animal may be somewhat relieved by the application of olive or 

 neat's-foot oil, or any emollient ointment. 



When too extensive a blister has been employed, or, from the intensity 

 of the original inflammation, the blister has not risen, (for no two intense 

 inflammations can exist in neighbouring parts at the same time,) strangury, 

 or great difficulty in passing urine, or even suppression of it, has occurred. 

 The careful washing off of the blister, and the administration of plenty of 

 warm water, with opium, and bleeding if the symptoms run high, will 

 generally remove this unpleasant effect. 



An infusion of two ounces of the flies in a pint of oil of turpentine, for 

 several days, is occasionally used as a Hquid blister; and when sufficiently 

 lowered with common oil, it is called a sweating oil, for it maintains a 

 certain degree of irritation and inflammation on the skin, but not sufficient 

 to blister,°and thus gradually abates or removes some old or deep inflam- 

 mation, or cause of lameness. 



Cantharides have lately been recommended to be given internally, ni 

 doses, daily, or twice in the day, of five grains, and increasing the dose 

 to fifteen grains, for the cure of glanders. The experiments are yet too 

 few and Indecisive to admit of ^any satisfactory conclusion. In these 

 doses the fly has not been injurious, and the experiments are well worth 

 prosecuting. 



Carraways.— These and ginger are retained as the only cordials requi- 

 site for the horse. 



Castor Oil is here introduced again to warn the horse-owner and the 

 practitioner against the too frequent use of it. If it is a purgative in the 

 horse, it must^be given in the enormous and expensive doses of a pound 

 or a pound and a half; even then it is uncertain in its effect— often gripes, 

 and is unsafe and dangerous. 



Catechu, Japan earth, yet no earth, but extracted from the wood of 

 one of the acacia trees, is a very useful astringent. It is given in super- 

 purgation, in doses of one or two drachms, with one or one and a half 

 drachm of opium, as a yet more powerful astringent ; four drachms of 

 chalk, to neutralize any acid in the stomach or bowels, and two drachms 

 of powdered gum beins: also added, to sheath the over-irritated mucous coat 

 of the intestines. It'^is not often adulterated in our country, but grossly 

 so abroad — fine sand and aluminous earth being mixed with the extract. 

 It should not be given with any alkali, yet the prescription just recom- 

 mended contains chalk. But although the chalk, being an alkali, 

 weakens the astringency of the catechu, it probably neutralizes some 

 acid in the stomach or bowels, which would have diminished the power 

 of the catechu to a greater degree. It must not be given in conjunction 

 with any metallic salt, for the tannin or gallic acid, on which its power 

 chiefly or entirely depends, has an affmity for all metals, and will unite 

 with them, and form a gallate of them, possessing little astringent energy. 

 Common ink is the union of this tannin principle with iron. 



A tincture of catechu is sometimes made by macerating three ounces 

 of the powder in a quart of spirit for a fortnight. It is very excellent 

 for wounds; and, with the aloes, constitutes all that we want of a 

 balsamic nature for the purpose of hastening the healing process of 

 wounds. 



Caustics. — These are sometimes necessary to destroy fungous excres- 



2 C 3 



