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hardly be sufficiently estimated. It would enable many an invalid, at a cheap and easy rate, to show "a clean bill of health;" and there are few who would consider the prescription to be otherwise than palatable.

CHAPTER V.

On the Hygienic effects of Clothing.-Functions of the Skin.-Extent and Character of the Cutaneous Secretions.-Effects of the Cutaneous and Pulmonary Exhalations.-Sympathetic Dependence between the Skin, Mucous Membranes, &c.—Materials of Clothing. -Good and Bad Conductors of Heat.-Relative amount of Protection to the System afforded by the Wear of Articles made of Flax, Cotton, Silk, and Wool.-Electrical Phenomena of the Animal Economy.-Use of Silk, Flannel, Leather, Cotton, &c., worn next to the Surface of the Body.-Value of Flannel worn as an Undergarment, in different Climates and Circumstances.-Dr. James Johnson, on the Hygienic Effects of the Costumes of the Oriental Nations.-Importance of Adequate Clothing to the Feet.-Comments on some dangerous Customs in regard to Dress.-Strictures on the Use and Abuse of Stays.-Effect of the Bed and BedClothes on Health and Disease.-Radiation of Heat.-Colour of Clothes, and its Effect.-A Suggestion for the Sick Room.

THE great extent of the surface of the body, and the large amount of the secretion that is constantly proceeding from it, either in the unperceived form of a vapour, or in the form of a fluid, renders the regular and adequate discharge of the functions of the skin not only important to health, but necessary even to the continuance of life.

In men of average size, the extent of the surface of the body is computed to be no less than 2500 square inches; and M. Seguin found, that, on an average, 18 grains of fluid were discharged in the minute, by

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the skin and the lungs,―of which, the skin was computed to exhale 11, and the lungs 7 grains. The minimum exhalation from both the cutaneous and pulmonary tissues, amounted in these experiments to 11 grains per minute; the maximum exhalation, when the system was in a state of rest, was found to be 32 grains per minute. According to these data, the maximum of matter lost or expended in these ways in the course of 24 hours, amounts to 5 pounds, and the minimum to 1 pound, 11 ounces, and 4 drachms; or, taking the average of 11 grains in the minute, the whole quantity amounts to 29 ounces of fluid. To arrive at some of these results, M. Seguin had himself securely fastened up in a bag, made of a thin and impervious material, with an aperture in it, the edges of which were fastened to his lips with a mixture of turpentine and pitch; by which contrivance, the whole of the pulmonary exhalation was permitted to escape, while the whole of the cutaneous secretion was retained in the bag. By causing himself to be weighed carefully, in an accurate balance, before the experiment, and again before leaving the bag, and again after he had got out of the bag, deducting the loss sustained before leaving the bag from the total loss, he was enabled to estimate the amount expended during the time, both in the pulmonary and in the cutaneous exhalations.

There is a comparatively small amount of solid constituents lost to the system in these exhalations; not supposed to exceed 7 or 8 scruples in the 24 hours;

the large remainder being mere water, together with carbonic acid, and perhaps some nitrogen.

Under some circumstances, there is sufficient reason to believe that a much larger amount of exhalation may take place from the lungs and the skin, than even the experiments of M. Seguin would have led us to infer. Dr. Southwood Smith relates some observations that were made upon labourers at the Phoenix Gas Works, who were employed twice a day in drawing and charging the retorts, and in making up the fires, which usually occupies about an hour; the labour is performed in the open air, but involves the exposure to a considerable degree of heat. On a foggy and calm day at the end of November, when the temperature of the external air was 39°, and the men continued at their work for an hour and a quarter, the greatest loss observed was 2 pounds, 15 ounces; and the average loss of eight men was 2 pounds, 1 ounce. On a bright clear day, in the middle of the same month, when the temperature of the air was 60°, without much wind, the greatest loss was 4 pounds, 3 ounces; and the average loss was 3 pounds, 6 ounces. very bright day in June, when the temperature of the air was again 60°, without much wind, the greatest loss (occurring in a man who had worked in a very hot place) was 5 pounds, 2 ounces; and the average during the hour that was lost by the men severally, was 2 pounds, 8 ounces.

And on a

In truth, the age of the individual, the sex, the

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dryness or moisture of the air, the temperature of the air, the degree of the exertion that is being made, the condition of the system, as to health or ailment, as to weakness or strength, will, each and all, considerably modify the amount of the exhalations from the body, as well as modify their character. There is little doubt, that, under circumstances of extreme exertion, as well as under those of many forms of bodily indisposition, a considerable amount of animal matter, as well as saline matter, is carried out of the body in this way. The principal ingredient of the salts of the exhalations is chloride of sodium; they have usually a slight acid reaction, due probably to a mixture of acetic, lactic, and butyric acids, in variable but very minute proportions, according to the health and strength of the system; there are generally likewise traces of ammonia, and of an animal extractive matter.

Of the extent of the secretions from the skin, no more need be said. The importance of its functions in this respect, is no less great. Of so great moment are they, that whatever unduly checks these secretions, -as cold, by suddenly or rapidly carrying off its heat, and impeding the circulation of the blood through the vessels which are ramified over it,-is almost certain to be followed by more or less indications of morbid action. The amount of the cutaneous exhalations is increased by a light and dry atmosphere; and is lessened by a damp, vapoury, dense, and calm atmosphere. During and immediately after the meals, the exhalation is said to be at its minimum ;