BLISTERS are medicinal agents which, when applied to the skin, raise the cuticle into small vesicles filled with serous fluid. They are applied either in the form of plas ters or in a fluid state, as.suita the, convenience of the person or part, and have for their object the establishing of a counter-Irritation or diversion of inflammatory action from a part in which it cannot be reached by remedies, or from some organ where it may do permanent mischief, to some more superficial part of the body.
The most common blister in use is made of cantharides (q.v.) or Spanish fly (cantharis t*.sicatoria), Cantharides, mixed with a couvenient proportion of lard and wax, forum the blistering ointment of ordinary use; the only objection to this preparation being, that if applied too long it produces distressing affections of the urinary bladder. In young children and very thin-skinned persons, a layer of silver paper, or thin gauze wet with vinegar, may be laid between the blister and the skin. But under no eire?un stances should a blister be left long upon children, as it may produce sores which am apt to take on an unhealthy action, and are ditticult to heal.
Mustard (sinapis nigra) is frequently used, but left on sufficiently long to pro duce blistering. Tincture of eantharides, eroton oil, mad strong liquor ammonia!, tartar emetic ointment, and many others, tire used in practice.
If the occasion for the blister passes off, the vesicles should he pricked, and their fluid contents allowed to trickle away, the vesicated surface being then dressed with some cold cream or lard. But if it should appear 4esirable to promote a discharge from the skin, the raised cuticles may be snipped off, and the blister either applied again at intervals, or some stimulating ointment as the savine (juniperus sabilut) made use of Great cleanliness should be observed itt dressing the part.
Of late years, B. have been much used for the dispersion of glandular tumors, and are also applied over the surfaces of indolent ulcers, with the view of increasing the vascularity of he part. For old diseases of joints, 13.. ought to be placed at a little dis tance from the affected joint.