Burns are produced by heated solids, or by the flames of some combustible substance, solid, liquid, or gaseous; scalds are produced by heated steam or liquid. The worst burns which occur commonly arise from the explosion of gunpowder or inflammable gases, or from the dresses of children or of females catching fire; the worst scalds, from accidents in breweries, manufactories, laboratories, and steamboats. The severity of the accident depends mainly on the intensity of the heat of the burning body, together with the extent of surface and the vitality of the parts involved in the injury. The immediate effect -of scalds is generally less violent than that of burns. Fluids, not being capable of acquiring so high a degree of temperature as some solids, cannot act with the same violence on a given point; but, flowing about with great facility, their effects often become more serious by extending to a very large surface of the body. A burn which utterly and instantaneously destroys the part it touches may be free from dangerous complications if the injured part be circumscribed within a small compass; while a scald apparently much less severe in its immediate effects, being more or less diffused, is always attended with different degrees of injury in different parts of its course, and may be very serious in its results, although apparently less violent in its first effects on any given part.

The extent of the surface involved, the depth of the injury, the vitality and the sensibility of the parts affected, must all be duly weighed in estimating the severity and the danger of an accident in any given case of burn or scald. In ordinary burns and scalds the immediate seat of injury is the skin or the external surface, one of the most vital parts of the frame. The skin is a highly organized membrane, endowed with acute sensibility. Burns and scalds, therefore, are more dangerous in proportion to the amount of surface involved than in proportion to the depths attained in a limited extent, for the outer layers are the most highly organized and sensitive parts of the cutaneous system. The outermost of all, however, the epidermis, being a mere coat of horny varnish, is the least sensitive; and where the injury is slight and altogether superficial, though extensive, the mischief is but trifling at first, and may be easily remedied; although unpleasant complications may ensue if the superficial injury is neglected, and the parts beneath are long exposed to the action of the air, which causes irritation, pain, and inflammation.

When the injury to the skin is so serious and extensive as to arrest the physiological action of this organ over a great part of its surface, this fact alone is usually sufficient to produce a fatal result. The suffering and shock to the nervous system, when sensibility has not been completely deadened, combine to make the condition of the patient after severe burns or scalds almost hopeless; but the worst cases might often be avoided by a little knowledge and self-possession on the part of the sufferer at the time of the accident, and a fatal contingency be transformed into a temporary injury. - Where the body is enveloped in flames, from the clothes being on fire, the first thing to be done is to lie down on the floor and roll the carpet or a rug, or any cloth or garment, closely round the body, so as to exclude the air from the burning dress, and thus put out the flame. Or, lie down at once and roll the body over the burning clothes, calling to some one near to throw a blanket or a cloth of any sort, wet or dry, or water, over you as you lie on the floor, stifling the burning clothes between your body and the ground. If the clothes of a child or a grown person near you should take fire, pursue the same method.

The upright position is the worst, being favorable to the spread of the flames, and allowing them to reach the upper and most vital portions of the body, trunk, head, face, and neck. Fright causes children to run to and fro for help, and this increases the currents of surrounding air, and helps the flame to spread. Merely hugging the child rapidly and closely in your arms, and rolling slowly on the floor with it, enveloping the flaming part with any portion of your own dress, will stifle out the air and flame together. Presence of mind alone suflices. In every case, and under all conditions, the main thing to be done at first is to stifle the flames by shutting out the air. - When the accident has happened, the burned or scalded parts should be immersed at once in cold water, or enveloped in wet cloths, or in dry cotton, or in flour, bran, or oiled muslin, or anything which is convenient to keep out the air from the injured surface of the skin. Immersion in cold water is the best, where it is practicable; because it not only shuts off the air, but causes a rapid rush of temperature from the injured tissues to the cold water, analogous to the violent rush of heat from the burning or scalding medium to the skin in the first instance, though in an opposite direction; and this inverse action soothes the nerves of sense, and thus answers the first requirement by diminishing the shock to the whole system from intensity of pain.

Some persons recommend stimulating lotions of brandy or spirits of wine, oil of turpentine, or vinegar, kept on the injured parts by means of lint, cotton, or old linen soaked in the liquid; others prefer soap and water, with or without creosote; and much difference of opinion exists with regard to the best means. An oil-skin, a soapy film, a coat of simple ointment, of cotton wool, or of flour, or anything which will exclude the air and not irritate the injured parts, will serve the purpose very well; and all the theories about peculiar modes of action in the various stimulating substances are more or less, it would appear, imaginary adjuncts to the simple fact of keeping out the air. When the pain has been arrested by the action of cold water, a delicate soap-and-water film upon the injured parts, surrounded by an oil-skin, or a layer of cotton wool, and bandaged carefully to keep the application in its place, are all that is required in ordinary cases of burns and scalds, until medical assistance is procured.