266 DADD 8 VETERINARY MEDICINE AND SURGERY. 
wash off the blistering matter, thereby saving loss of hair, but 
there is more of apparent than real goed in this plan. Ifa blie 
ter be necessary, it requires all its activity. 
Ammoniucal blister.—Spanish flies are only efficacious when the 
animal can afford to wait their action, which is rather slow. In 
most of the acute diseases, the horse would perish before the blis- 
ter began to rise, wherefore resort has been had to boiling water 
and red-hot iron. The action of these last coarse and brutal 
measures was alone controlled by the violence of the internal in- 
flammation, and, if the practitioner was mistaken in his estimate 
of the immediate danger, extensive and lasting blemish was the 
consequence. We have in the liquor ammonia an agent quite as 
formidable as boiling water or heated iron, but it is rather longer 
in displaying its force; wherefore, it allows time for watching its 
action, and of checking it the instant it has sufficiently blistered 
the skin. It is true the liquor ammonia upon the skin can not be 
removed, neither need if be counteracted. Ammonia is like steam, 
only powerful when cunfined. The ordinary soap liniment, if 
covered over, would, because of the ammonia it contains, produce 
a lasting blemish; but every veterinary surgeon knows how very 
harmless a preparation that is when simply rubbed upon the sur- 
face. So, when we desire the active effects of liquor ammonia, we 
double a blanket ur rug four or five times und hold it over the 
liquid. It takes from ten to twenty minutes to raise a blister, and 
it consequently can, from time to time, be observed ; and when its 
action has reached the wished-for point, all we have to do, effectu- 
ally to stop it, is to take away the rug or blanket. That remove, 
the free surface and the heat of the body occasions the ammoniacal 
vapor to be dispersed, and the animal is safe. 
ROWELLING. 
towels acts as foreign substances within the body. They cause 
irritation and suppuration, whereby more deep-seated inflamma- 
tions are supposed to be removed. They are, however, often very 
cunvenient, because they stand as sign-boards to show the proprie- 
tor that sumething has been done. The common mode of making 
a rowel is after the following manner: A slit is first made by 
means of the rowel scissors, on any part of the integuments, held 
between the finger and thumb. With the handle of the sciseora 
