Cleanliness in respect to bedclothes is very important. Organic matters evolved from the skin, lungs, etc., hang about the bed-linen, and give the bedroom the “close smell” which can be perceived on entering it in the morning straight from the fresh air. The beds should not be made directly after being evacuated, but the clothes should be thrown over the bottom of the bed, the bolsters and mattress well shaken, and every part exposed to a free current of air during the greater part of the morning, before re-arranging the clothes. Eider-down quilts, unless frequently ventilated by exposure to outside air, are unwholesome. Superfluous bedroom furniture should be avoided, as it all takes away from the breathing-space. Bed-hangings should be reduced to a minimum, and all excretory matters covered up during their stay in the room, and removed as early as possible.
Cleanliness of the house is also very important as a means of health. Dust, in however obscure a corner it rests, attracts to itself organic matters, and forms a soil in which disease germs may grow. Besides this, it devitalises the air, depriving it of its active oxygen. (See also page [101]).
Dust in the streets serves to carry about various diseases, besides mechanically irritating any part it comes in contact with, producing bronchitis, etc.
[CHAPTER XL.]
CLOTHING.
Physiological Considerations.—The average temperature of the surface of the body in man is 98·4 to 98·6°. The maintenance of a tolerably uniform temperature is an essential condition of life. The factors governing the temperature of the body are the amount of heat produced and the amount lost. If more heat escapes, more has to be generated; and the source of all the heat produced in the body is the food taken. This becomes changed by the metabolic processes occurring in the body which produce heat.
Heat is lost, (1) by the skin; (2) in respiration, the expired air having been heated during its stay in the lungs; (3) with the food and drink taken, if not at the temperature of the body; (4) with the excreta; and (5) by transformation of heat into mechanical energy. Of the whole loss by these different channels, probably eighty to ninety per cent. is through the skin.
The Loss of Heat by the Skin is in three different ways. First, by conduction, when the skin comes in contact with anything cooler than itself; secondly, by radiation into space; and thirdly, by evaporation of the perspiration. The last cause produces a considerable reduction of temperature, even when the perspiration is not so abundant as to be visible, but is in the form of insensible perspiration. The losses by these different sources vary in amount; when one is increased, another is diminished, by way of compensation. Thus, in very cold weather, the amount of radiation and conduction of heat are increased; but evaporation greatly decreases, and the diminished loss of heat in this respect counter-balances in some degree the increased loss by radiation and conduction.
When the external warmth is considerable, increased evaporation occurs; while when the weather is cold, the cutaneous arteries contract, and less blood goes to the skin, and so the loss of heat is diminished. In most climates, however, this action of the skin requires to be supplemented by some kind of clothing.
Requisites of Dress.—1. The first and most important requirement is that clothing should maintain a uniform and equable temperature in all parts of the body.