660. _The material for clothing should not possess the property of absorbing and retaining moisture._ Dampness, or moisture, renders apparel a good conductor of heat; beside, if the perspired fluid, and the saline material it holds in solution, are readily absorbed by the clothing, they become sources of irritation to the skin with which the apparel comes in contact. -=-=-=-=-=-=-=-=-=-=-=-= 657-716. Give the hygiene of the skin. 657. What influences modify the action of the oil and perspiratory glands? To what must attention be given to maintain a healthy action of the skin? 658. What is said in regard to the clothing? 659. Mention a property that the material for clothing should possess. 660. What property in the selection of clothing should we avoid? Why? -=-=-=-=-=-=-=-=-=-=-=-= 661. _Furs_ contain a greater amount of air in their meshes, than any other article, and they absorb no moisture; consequently, as an article of dress, they are best adapted to those who are exposed to great vicissitudes of heat and cold. 662. _Woollen cloth_ retains more air in its meshes than any other article except furs and eider down, and it absorbs but very little moisture. These properties, together with its comparative cheapness, render it a good article of apparel for all classes of persons. The only objection to its general use is, the disturbance of the electricity of the system, and the irritation to delicate skins from the roughness of its fibres. _Observation._ Flannels are not only beneficial, during the cold season, in preventing colds and rheumatism, but they are of great utility in the warm season, in shielding the system from the chills at evening, that induce disease of the alimentary canal. Their general use among children and delicate females, would be a preventive of the "season complaints" prevalent in the months of August and September. 663. _Cotton_ contains less air in its meshes than woollen, but much more than linen. In texture, it is smoother than wool, and less liable to irritate the skin. This fabric absorbs moisture in a small degree. In all respects, it is well adapted for garments worn next the skin. When woollen flannels irritate the skin, they may be lined with cotton. 664. _Silk_ is not as good a conductor of heat as cotton, nor does it absorb moisture to any considerable degree; its texture is smooth, and does not irritate the skin; consequently, when the garment of this fabric has sufficient body or thickness, it is a good article for clothing. The greatest objection to its use is the disturbance of the electricity of the system, and its high price. -=-=-=-=-=-=-=-=-=-=-=-= 661. Give the properties of fur. As an article of dress, to whom are they best adapted? 662. Give the properties of woollen cloth. Is this a good article for clothing? What objection? What are the advantages of wearing flannels? 663. What are the qualities of cotton as an article of dress? 664. Of silk? -=-=-=-=-=-=-=-=-=-=-=-=