544 HYDROPATHY sheet pack, cooling compresses, spongings, and allied mea sures, these ends are attained with comparative ease, cer tainty, and simplicity, and with entire freedom from objectionable secondary effects. The agents of hydropathy are at once simple and complex, simple in their elements, and complex in their combinations and modifications. They afford the physician a series of effects almost infinite in variety, both in kind and in degree, both immediate and remote. According as heat and cold 1 are used in their extreme or their intermediate degrees, singly or in combination, successively or alter nately, momentarily or continuously, dry or moist, and according as the primary action is utilized or the secondary, do their effects differ. The direct or primary effect of cold is to depress, cool, and deplete the part concerned. If its exhibition is brief, reaction (an important factor in hydro pathic practice) quickly establishes an opposite condition, stimulating the part, and determining an increased flow of blood to it, with increase of its temperature and vital activity. If it is continuous, the primary depression is maintained, and the revulsive or secondary effect delayed or averted. The direct effect of heat is to increase the amount of blood present; but if the exhibition is brief, and evaporation is permitted, the contrary effect is pro duced, viz., depression, coolness, and depletion ; if it is continuous, the primary effect is preserved. Thus with truth it may be said that cold heats and heat cools, while the converse holds good, and that by simple variations of detail. From the intermediate temperatures (80 to 100) simple sedative effects are obtained, with absence of second ary or revulsive effects in proportion as the temperature of the part is approximated to. Results vary also accord ing to the heat of the subject. In local inflammations, continuous cold benumbs and contracts, continuous heat soothes and relaxes. Momentary cold excites, heats by reaction, and intensifies inflammation ; while momentary heat soothes and ultimately cools the inflamed part by the after evaporation. In the earlier stages and acute varieties of inflammation, therefore, continuous cold or transient hot applications are appropriate, and brief applications of cold in the later, congestive, and chronic forms. But where the local inflammation coexists with general feverishness, con tinuous cold as the local application is preferable, helping, as it does, to reduce the general exaltation of temperature. In collapse the low general temperature makes heat the best local application. On internal parts the application of heat and cold externally has definite therapeutic effects either identical or opposite (as remarked by John Hunter) through reflex or sympathetic nervous action. Through the vascular system also remote effects are produced, as in heating the lower extremities to derive blood from the brain. The counter relation also of the entire cutaneous surface to the internal organs, as the kidneys and alimen tary mucous membrane, is, in hydropathy, largely utilized for remedial purposes. This sympathy is familiar enough in the etiology of disease, which may be said likewise of all the physiological laws applied to curative purposes in hydropathy. The appliances and arrangements by means of which heat and cold are brought to bear on the economy are (a) Packings, hot and cold, general and local, sweating and cooling ; (V) hot air and steam baths ; (c) general baths, of hot water and cold ; (d) sitz, spinal, head, and foot baths ; (c) bandages (or compresses), wet and dry ; also (/) fomentations and poultices, hot and cold, sinapisms, stupes, rubbings, and water potations, hot and cold. (a.) Packings. The full pack consists of a wet sheet enveloping the body, with a number of dry blankets packed tightly over it, in cluding a macintosh covering or not. In an hour or less these are removed and ageneralbath administered. The pack is a derivative, 1 Roughly, and for practical purposes, temperature lower than 60 C may be called cold ; from 60 to 90, temperate or tepid ; from 90 C to 100, warm ; and above 100, hot (compare vol. iii. p. 440). sedative, sudorific, and stimulator of cutaneous excretion. There are numerous modifications of it, notably the cooling pack, where the wrappings are loose and scanty, permitting evaporation, and the application of indefinite duration, the sheet being rewetted as it dries; this is of great value in protracted febrile conditions. There are also local packs, to trunk, limbs, or head separately, which are derivative, soothing, or stimulating, according to circumstance and detail. (b. ) Hot air baths, the chief of which is the Turkish (properly, the Roman) bath, consisting of two or more chambers ranging in temperature from 120 to 212 or higher, but mainly used at 150 for curative purposes. Exposure is from twenty minutes up to two hours according to the effect sought, and is followed by a general bath, and occasionally by soaping an d shampooing. 1 1 is stimulating, derivative, depurative, sudorific, and alterative, powerfully promoting tissue change by increase of the natural waste and repair. It determines the blood to the surface, reducing internal congestions, is a potent diaphoretic, and, through the extremes of heat and cold, is an effec tive nervous and vascular stimulant and tonic. Morbid growths and secretions, as also the ursemic, gouty, and rheumatic diathesis, are beneficially influenced by it. The full pack and Turkish bath have between them usurped the place and bettered the function of the once familiar hot bath. The Russian or steam bath and the lamp bath are primitive and inferior varieties of the modern Turkish bath, the atmosphere of which cannot be too dry and pure. (c.) General baths comprise the rain (or needle), spray (or rose), shower, shallow, plunge, douche, wave, and common morning sponge baths, with the dripping sheet, and hot and cold spongings, and are combinations, as a rule, of hot and cold water. They are stimulating, tonic, derivative, and detergent. (d.) Local baths comprise the sitz (or sitting), douche (or spout ing), spinal, foot, and head baths, of hot or cold water, singly or in combination, successive or alternate. The sitz, head, and footbaths are used "flowing "on occasion.. Rapid alternations of hot and cold water have a powerful effect in vascular stasis and lethargy of the nervous system and absorbents, yielding valuable results in local congestions and chronic inflammations. (e.) Bandages (or compresses) are of two kinds, cooling, of wet material left exposed for evaporation, used in local inflammations and fevers ; and heating, of the same, covered with waterproof material, used in congestion, external or internal, for short or long periods. Poultices, warm, of bread, linseed, bran, &c., changed but twice in twenty-four hours, are identical in action with the heating bandage, and superior only in the greater warmth and consequent vital activity their closer application to the skin ensures. (/. ) Fomentations and poultices, hot or cold, sinapisms, stupes, rubefacients, irritants, frictions, kneadings, calisthenics, gymnastics, electricity, &c., are adjuncts largely employed in hydropathic practice. Water drinking, while still an important factor in hydro pathy, has declined somewhat since the early times of the system. But that which has from the first distinguished modern hydro pathy, and still makes its strict practice a thing apart, is the "crisis" so called. It is related of Priessnitz that, when a boy of fourteen, and treating a sprain, as was the native custom, with wet cloths, he observed an eruption appear beneath them, with immedi ate recovery of the part. Gradually the significance and wider application of this eruption dawned upon him, until it came to hold so prominent a place in his practice as to be regarded by many as his greatest discovery. The eruption coinciding in point of time with recovery as a rule, it was called the crisis, involving doubtless a reference to the term as used by Hippocrates and his successors. But with Priessnitz crisis attained a higher rank, a wider application, and a more definite character. He first showed it to be producible at will under given conditions of the patient, and amenable to direction and control. This eruption, it is claimed, appears only in morbid states of the blood (cachexia) resulting from derangement or defect in the organs of assimilation or excretion or both (e.g., gout, rheumatism), or from the presence of a specific poison (e.g., syphilis). The continuous application to a given tract of skin of the heating bandage or poultice (mediums merely for the exhibition of warmth and moisture) stimulates, in a cumulative way, its vascular and nervous activity, and leads, it may be in a few days or weeks (in some cases hours, in others months), to an eruption, papular, then pustular, and ultimately resolving itself into a suppurating surface commensurate with the area covered by the bandage. There is, in the latter stage, a copious discharge of yellowish-green pus, usually foetid, varied occasionally with patches of brown, blue, or metallic green, and accompanied with itching, sometimes intense. The general temperature is not, as a rule, disturbed ; the pulse, except perhaps for the first day or two, falls, if previously quick, to a natural rate ; the weight and strength, in the most favourable cases from the outset, and in the rest later on, increase, and it is not un common to find the anomaly of a patient exulting in freedom from suffering and a return of the impulses of health simultaneously with the appearance of an extensive inflammation of the skin. The applications, continued without intermission and unaltered (save a3 cleanliness requires) for weeks or months, according to the nature
of the case, are at last no more stained with pus but with serum
