Cold is primarily sedative, and secondarily stimulant through reaction. Its astringent influence, in relation to which alone it is here considered, is merely incidental to the sedative. The effects are essentially the same as those already described as the result of the action of astringents generally, and need not be repeated. The cutis anserina, or goose-flesh, in which the roughness is owing to the shrinking of the skin around the prominent sebaceous and hair follicles, is even more striking than the similar effect from other astringents. There is also from cold a greater degree of stiffness or firmness in the contracting tissue.

1. Mode of Operation

The astringent effect of cold is partly physical, and partly vital. It is a general law of heat, that bodies expand with its increase and contract with its diminution; and the contraction produced in living structure by cold is in some measure undoubtedly the result of this law. The peculiar density and stiffness of tissue may be ascribed, in part, to the solidification by cold of the oil globules of the adipose matter. But I am disposed to ascribe the diminution of bulk still more to the sedative influence of the cold upon the vital forces of the part, and the consequent inability of the capillaries to receive and carry forward the blood. According to this view, it is rather the part which shrinks, because the blood does not enter it in normal proportion, than the blood that is expelled, because the capillaries are contracted; though the two causes probably co-operate. It is not impossible that a diminution of heat may, in some unexplained manner, act as a stimulant to the organic contractility, exactly in the same mode as the medicinal astringents; but the former explanation is more accordant with the received views of the sedative influence of cold, which would seem to be a necessary corollary to the stimulant action of heat. There can be no doubt that the astringent influence of cold is transmitted, through nervous communication, from the external surface where it is applied, to certain internal surfaces, especially those of the respiratory and alimentary mucous membranes, and the lining tissue of the uterus.

The progress of physiology, since the publication of the first edition of this work, enables us to advance one step further in explaining the contraction produced by cold, though, it must be confessed, still somewhat conjecturally. It has been determined that one of the offices of the cerebral nerve-centres is to promote active capillary expansion, while the ganglionic system has a directly contrary effect. Now it is not improbable that the depressing influence of cold, transmitted by direct nervous connection to the cerebral centres, may diminish this expansive action of the former, while the shock it produces on the point of application may prove excitant to the latter, and thereby produce contraction in the capillaries; the two influences, though so different in their nature, thus co-operating to the same result.

2. Therapeutic Effects

2. Therapeutic Effects. The therapeutic effects of cold as an astringent are, for the most part, the same as those of the class in general. It is, however, seldom resorted to with the view of checking morbid secretion. Sometimes it is used to moderate or arrest excessive sweating, but cautiously, and with much reserve. By far the most extensive and useful application of this agency of cold is to the suppression of hemorrhage. In this it exhibits extraordinary powers. The effect is generally ascribed to the closure of the bleeding orifices, and no doubt correctly in part; but I am inclined to think that still more is due to the depression of the local circulating forces through the sedative influence of the cold. The styptic effects of the remedy have also been attributed, in some measure, to an increased coagulability of the blood; but this is probably a mistake; as cold retards rather than hastens coagulation, and for a very good reason; for, otherwise, exposure to a very low temperature might endanger coagulation of the blood, and consequent inevitable gangrene, in the most exposed parts. Blood may even be frozen without coagulating, and, upon thawing, may still retain the property. Hence, frozen parts may by proper management often be restored, which could not happen if the blood had all coagulated in the vessels. Almost all forms of hemorrhage may be treated advantageously by cold, unless the vital forces have been so much prostrated as to be able to bear no further reduction.

This remedy is less applicable, than other astringent measures, to the treatment of simple relaxation; at least in reference to its direct and primary action. It may, however, sometimes be advantageously used in varicocele, and in hemorrhoidal and aneurismal tumours. It has been employed also to aid in the reduction of strangulated hernia, in which it is supposed to be useful by diminishing the bulk of the contents of the sac, in greater degree than it contracts the hernial orifice, so as to favour the return of the former through the latter; but this is scarcely an example of the mode of operation here referred to.

For fulfilling the third indication for the use of astringents, that, namely of obviating early inflammation by emptying the vessels, cold is an admirable remedy; but it is still more useful in that affection as a sedative, and will be fully treated of, in relation to its antiphlogistic action, under the head of sedative remedies.

Cold as an astringent may be applied by means of cold air, cold water, ice or snow, evaporating liquids, and frig-orific mixtures. Cold water may be applied upon linen rags or towels, by means of the douche, or by affusion, and may vary in temperature from 32° to 60°, according to the amount of effect desired. Ice and snore may be applied in bladders, or wrapped up in cloths: and the former may be used in larger or smaller fragments, or finely pounded. Ether is the liquid most frequently employed with a view to the production of cold by evaporation; and its effects in this way may be greatly increased by blowing on it, by means of a pair of billows, as it is dropped upon the surface. Brought, in the state of spray, by means of the atomizer, into contact with any part of the body, it is capable of producing an intense degree of cold, so as to act as a complete local anaesthetic; but of this application of the liquid more will be said hereafter. The most convenient frigorific mixture, in the absence of cold water or ice, is made by mixing, in a pint of water, four ounces of sal ammoniac and the same quantity of nitre, which may be applied in a bladder.

The following applications are made of cold in one or another of the above forms. Cold air is sometimes useful in arresting traumatic hemorrhage, and checking profuse perspiration. In the same kind of hemorrhage, very cold water or ice may sometimes be advanta-geouly resorted to, when the bleeding vessels are too small to be tied, or not conveniently reached, as in some operations about the rectum. vagina, etc.

In epistaxis the water or ice may be applied over the nose, to the back of the neck to the genitals in obstinate eases, or by affusion to the head.

The same application may be made, in very obstinate haemoptysis, to the breast or axilla; but in this variety of hemorrhage the remedy should be used with caution, from the danger of producing congestion in the pulmonary parenchyma.

In haematemesis, the most effectual method of employing this remedy is to allow the patient to swallow small pieces of ice. which by dissolving in the stomach, will keep up a constant frigorific effect on the organ. There might be danger, in the external use of cold in this affection, of producing congestion of the portal circle, which might more than counterbalance the sympathetic astringent effect on the mucous membrane.

In hematuria, Uterine hemorrhage, and bleeding from the. rectum, the applications may be made over the sacrum, to the perinaeum, and over the pubes; and the douche, falling from a considerable height upon the lower part of the abdomen, is often more efficient than the simple contact of the water or ice. Very cold water has sometimes been injected into the rectum and vagina; and pieces of ice have been introduced into the same cavities, and even into the uterus, when a very strong impression was desired.

In varicose swellings and aneurismal tumours, one or another of the several modes of application mentioned may be employed, according to the situation of the part, or other circumstances affecting their convenience or efficiency. In strangulated hernia, recourse has been occasionally had to the evaporation of ether, as well as to other frigorific measures, especially to pounded ice or snow in cloths or bladders.

But in all these cases, especially when ice or snow is employed, care should be taken not to allow so long a continuance of the application as to endanger the freezing and consequent mortification of the part; and, when ice is introduced either into the stomach or rectum, to guard with special caution against a too great depressing effect