In our enumeration of the diseases benefited by blisters, we shall be guided by their effects, and shall consider them as altering the determination of the fluids from parts overloaded; influencing the determination of the nervous power; as stimulants, evacuants, and cordials.

In fevers, we generally find the equilibrium of the circulation greatly disturbed; and, in general, the two organs which chiefly suffer from over distention, are the brain and the liver. We have a more ready access to the latter by more easy remedies. The distention of the vessels of the brain is chiefly relieved by blisters. In some inflammatory fevers the load in the head is considerable; and in cases not truly phrenitic, the delirium is of that wild and violent kind which approaches very nearly to phrensy. When bleeding is admissible, it must be premised; and, in other cases, the stomach and bowels must be freely emptied. Blisters will then greatly relieve, but they should be applied very near the head, and in general immediately below the hair on the back part of the head. Near the head we have still the temples, as well as the parts behind the ears, for a succession of blisters, if necessary; since the first effects of this remedy are those most beneficial, and it is unnecessary to continue the discharge from one part more than thirty-six or forty-eight hours. We must still however look forward to the possibility of a continued determination; and should the fever not terminate in fourteen or sixteen days, shave the vertex, that cold applications may be employed, or any accidental scratch be healed, before it be necessary to apply a blister to that part. These frequent repetitions of blisters are however seldom necessary.

In the typhus there is also a determination to the head, though less violent, and with inflammation less active. In these our chief reliance is on blisters, for bleeding is improper, and active purging sometimes inadmissible. The inexperienced practitioner has been alarmed by the debilitating powers of this remedy; but these are observed in very few constitutions, nor have we ever found them permanently injurious in fevers of this kind. In the worst kind of asthenic fevers they are less proper; and in highly putrid fevers, they have been considered as rather injurious than useful.

The greatest advantages of blisters are experienced in inflammations. In phrenitic cases their administration does not greatly differ from that we have described, when speaking of inflammatory fevers. In sore throats we have mentioned them as highly useful, and they should extend from behind the ear under the lower jaw to the trachea. In every inflammation of the face they should be applied in the same way, and are highly useful. The tic doloureux,in Dr. Fothergill's language, the dolor faciei crucians, is an exception to this rule, and indeed can scarcely be called an inflammation. In inflammatory affections of the chest, blisters are our chief dependance; and in every disease of this kind, except perhaps the putrid pneumonia, they are of service: in this, however, they are certainly not injurious, and, as we have said, they are not-so in angina maligna. We spoke with less confidence of their effects in highly putrid fevers, as these have not very often occurred to us. In inflammatory coughs they are useful; and in many of these, especially if not attended with expectoration, they seem to be more beneficial when applied to the bone of the neck, than to any part of the chest. In general, however, if there is any fixed pain in any part, to it they must be directed. To this subject, however, we must return in the articles of Pnecmonia and Hectic fevers. In croop we have said they are used, but, like most other remedies, with little advantage: and in hooping cough they rather guard against any inflammatory accumulation in the chest, than shorten or materially mitigate the disease.

In inflammations of the abdomen they are highly useful, with the exception only of those of the bladder; but even in the latter, when the inflammation is confined to its neck, a short application of a blister to the perinaeum has been of service. In all local pains of the abdomen blisters will relieve, and we think they even facilitate the passage of a gall-stone through the duct. They are certainly useful in preventing inflammation of that part from the distention. In gastrodynia, whatever be the cause, they seem to relieve.

In all inflammations of the joints blisters are useful: even the paroxysms of gout they shorten and mitigate, though we have had reason to fear with disadvantage to the constitution. -The white swelling is a peculiar disorder, which we cannot at present enlarge on. It consists however in its commencement of a rigidity of the ligaments, and in its progress of deep seated inflammation. In the early state, there is perhaps no more certain remedy than blisters repeatedly applied: their first action seems to be the most useful. Modern practitioners have substituted the stimulusof emetic tartar in these and some other swellings, particularly the bronchocele, it is said with success. In our hands.

however, it has appeared less useful; and the peculiar deep irritable little sores which it occasions soon prevent the use of this and every other external application.

In the exanthemata, we find blisters chiefly useful in small pox and measles. In the former, when the head and breast are greatly loaded previous to the eruption, they are often useful, and occasion a more mild and distinct kind. When repelled, also, they assist in their reproduction, and often prevent the inconveniences which arise from their disappearance. In measles they are more useful, on account of the violent catarrhal inflammation which often becomes pneumonic.

Active hemorrhages are greatly relieved by blisters. The sanguine effusions in the brain producing apoplexies require their immediate application, without waiting for the effect of evacuations. Bleedings from the nose and the lungs are equally relieved by them. It has not been usual to apply them in discharges of blood from the bowels, chiefly perhaps because these are seldom of the active kind; and as it is not easy to ascertain the part, particularly affected, with accuracy. Discharges of blood from the kidneys and bladder also are not relieved by blisters. In diarrhaeas from the measles they are supposed serviceable; and indeed this must be considered as an inflammatory complaint. In dysentery they are said to relieve pain, but are seldom employed.

Blisters are employed also to alter the determination of the nervous power. This is certainly a vague indication; but they are useful in spasmodic pains of the intestines when there is no inflammation; they relieve the paroxysms of angina pectoris, of spasmodic asthma, as well as epilepsies not connected with local plethora and extravasation; they remove pains in the stomach arising wholly from the irregular action of that organ; and coughs that are nervous and independent of inflammation. These are certainly facts, though the mode of their operation may be doubted.

Though the stimulus of blisters be transitory and local, yet they are certainly useful as stimulants. On the back part of the neck they stimulate the nerves sent to the throat, and relieve aphonia, and deglutition impeded from palsy. On the internal humerus they relieve paralytic affections of the hands and fingers; on the internal part of the thigh they are equally useful in weakness of the legs. They are certainly employed as stimulants in palsy and apoplexy, yet their power as such is doubtful. It is too much the custom to accumulate stimulants and evacuants in these emergencies till we know not to what the relief is to be attributed, and unfortunately to what our failure is owing, for the little remaining excitability is often thus destroyed. A gentle breath will re-illumine the flame, which a violent wind will irrecoverably extinguish. In asphyxy, in carus, in catalepsy, and in hysteric affections, which for a time apparently destroy life, they have been employed as stimulants; yet we doubt if with any good effect, except in the species simulate.

As evacuants we have already mentioned the good effects of blisters in anasarca, in humoral asthma, and in serous apoplexies; nor does our recollection at present supply any other disease to which from this power they are applied. In tumours, and collections of a doubtful nature, setons and issues are preferred. Where the fluid to be discharged lies deeply imbedded, the two last are more useful.

We have mentioned the foundation of their employment as cordials. This rests, as we have seen, on a loose equivocal foundation; nor do we find them used by practitioners with this view, except in some cases of low nervous fever, in which their utility may perhaps be explained more satisfactorily by their power of altering the determination.

The inconveniences arising from cantharides have induced physicians to employ other stimulants with a view of exciting blisters. The flour of mustard, garlic, arum root, emetic tartar, and the vitriolic acid, have been used for this purpose. They produce, however, a very inadequate discharge, and we shall return to them under the title of rubefacients. The only substance which may probably with advantage be substituted, is the inner bark of the daphne mesereum or lau-reola. The small branches are cut into portions of the required length, and macerated in warm water or vinegar till the bark can be loosened. This must be applied to the part previously rubbed with vinegar.