[9] Opiates may indeed abate the smarting, or soreness, which is consequent to the immediate mechanical injury of wounds, or operations; but this relief is commonly only temporary; for the general action is very apt to be afterwards increased, and, consequently, union by adhesion is less likely to take place. [10] There are two general diseases which are connected with local actions, and which opium is supposed to cure, or prevent from taking place; the inflammatory fever, dependent on an wound, and the febrile state, consequent to a temporary increased action, or exertion of a particular part, or the whole of the system; as, for instance, the effect of parturition. The first of these is always aggravated by opium; the second, if it be not increased, cannot possibly be cured by it. The local applications are such as tend either simply to abate action in the part, or such as tend to change its nature, by exciting a specific change, or such as act in both ways. The first comprehends cold, the second the agentes dissimiles, and the third topical bleeding. Cold, applied directly to the inflamed part, is a most useful remedy, diminishing the action to a natural state; but, for this purpose, it must not be applied in too great a degree, otherwise we diminish the action so much, and so suddenly, (and, consequently, the power of the part) that recovery cannot take place. If we apply much cold to a healthy part, we sink its action so far, that it is irrecoverable; if we apply cold to an inflamed part, so as to diminish its action equally suddenly, and in the same proportion, we produce the same effect. Poultices of ice, or snow, are therefore highly dangerous; and even water, although it cannot be made nearly so cold as these. The same direction which has been given, with regard to the application of cold as a general remedy, ought also to be remembered, when we use it as a local application, namely, it ought to be carried just to such a degree, as shall diminish the morbid sensation, and ought to be so adjusted, as to keep the part nearly in its natural degree, or at least very little lower. For this purpose, it must be applied in moderation, repeatedly, and with assiduity; and not, as is commonly done, in a considerable degree at once, and renewed only at long intervals. Cold has been supposed to be useful as an active astringent, producing a contraction in the vessels; but it does not seem to possess any active power in producing such a state in the vessels to which it is applied. Where injury is taking place, from excessive action, cold, by abating it, may strengthen, and produce more natural contractions; but, when applied to a healthy part, it diminishes the action of that part, the blood is less forcibly circulated, and the part shrinks; it therefore stops active hemorrhage in the part on which it acts. When cold is applied suddenly, or to delicate parts, it excites an universal