CHAPTER XXXIX.

PERSONAL HYGIENE (_continued_)—CLEANLINESS.

=Physiological Considerations.=—The skin consists of a superficial part or epidermis, and a deeper part called the dermis or cutis.

Tubes of two kinds open on the surface of the skin, penetrating at their deeper ends into the cutis, viz. sweat or _sudoriparous glands_ and _sebaceous glands_. The sudoriparous glands are simple tubes, the lower ends of which lie coiled up in the dermis. Each tube when straightened out is about a quarter of an inch long. It has been estimated that in the palm of the hand there are 3,528 orifices of sudoriparous and sebaceous glands on a square inch of surface; reckoning each gland at 1∕4 inch long, this means 73½ feet of tubes in this small space. Assuming that there are 2,800 tubes to every square inch, and that the amount of surface in a man of ordinary height and bulk is 2,500 square inches, it follows that there are seven million pores in a man—that is, 1,750,000 inches, or nearly twenty-eight miles.

The perspiration secreted by the sudoriparous glands is constantly evaporating from the surface of the body. It is very important that the orifices of these glands should be kept open in order that the secretion may not be interfered with. Animals have been killed by covering their skin with gelatine, and so preventing the escape of perspiration.

The sebaceous glands are shorter than the sudoriparous, and commonly end alongside the hairs before the latter issue from the skin. They secrete an oily material which serves the purpose of a natural pomade. The sebaceous secretion also keeps the general surface of the skin unctuous and supple. The smell of the sebaceous secretion may be unpleasant, especially in the arm-pits and some other parts. Frequent washing is therefore desirable.

The =Conditions Due to Uncleanliness= are due to obstruction of the excretory ducts, to accumulation of _débris_ on the general surface of the skin, and to the consequent interference with the circulation.

1. The _obstruction_ of the sudoriparous pores of the skin interferes with the elimination of waste products by the perspiration; these are re-absorbed or retained in the system; consequently more work is thrown on the lungs and kidneys, and the equilibrium of health is destroyed.

Sebaceous obstruction causes an accumulation of oily secretion in the ducts. The black spots so commonly seen about the nose, are the blocked up orifices of sebaceous glands, and by squeezing the nose tiny threads of fatty matter are forced out from the interior of these glands. Pimples on the face are usually due to obstruction of the sebaceous glands; sometimes the obstruction leads to inflammation around the sebaceous gland (_acne_) which often permanently injures the skin.

2. _Accumulation_ of effete matter on the skin occurs, unless frequent ablutions are performed. The epidermis is constantly shedding its older and more superficial parts, in the form of minute scales or “scurf.” In the absence of frequent washing, the scales of epithelium tend to accumulate, the sebaceous secretion matting the scales together, and rendering them more adhesive. The saline matters of the perspiration also accumulate along with the scales and sebaceous secretion, and in virtue of their hygroscopic properties tend to keep the skin clammy and cold.

The obstruction of excretions and the accumulation of _débris_ lead to other consequences. Thus:—3. The _sensibility of the skin_ is dulled when the sensory papillæ are covered with dirt. The sensations received by the skin are important in regulating the temperature of the body. A cold external temperature should cause a reflex contraction of the small arteries bringing blood to the skin, thus diminishing the flow of blood and preventing undue loss of heat. Similarly, if the external temperature is high, or the internal development of heat is too great, these arteries dilate, and sending more blood to the skin, cause a greater loss of heat by radiation and conduction. Impaired sensibility of the skin leads to imperfect action of the reflex nervous mechanism to which the above effects are due, and consequently the dangers resulting from sudden alterations of temperature are greatly increased.

4. The _tendency to chills_ is increased, not only by deficiency of the nervous tone of the skin, but also by obstruction of the pores of the skin, and by the hygrometric action of the saline matter collected on it.

5. _Cutaneous diseases_ are due to, or favoured by, uncleanliness. These are of two kinds—_parasitic_ and _non-parasitic_. Acne, which is the chief non-parasitic disease favoured by uncleanliness, has been already mentioned.

Parasitic skin diseases are greatly favoured by the presence of a dirty skin, which affords a suitable soil for the development of the parasites. (See also page 275).

=Uses of Soap.=—Soap is produced by an action of an alkali on an oil. The alkali displaces glycerine from the oil, and forms an alkaline stearate, which is soap. Soft soap is chiefly stearate of potassium; hard soap is stearate of sodium. There may also be present the alkaline salts of oleic and palmitic acid. Soft soap is not used for washing the skin, as it is too irritating. All soaps contain a slight excess of soda; the greater this excess, the more irritating is the soap to delicate skins. Hard soaps may be also made with potash, if the fat employed be a solid one; but such soaps are rather softer than ordinary hard soaps, and more caustic. Cocoa-nut oil is used in making marine soaps, because, unlike all other kinds, it is not rendered insoluble by brine, and so will form a lather with sea-water. Normal soaps contain from 15 to 35 per cent. of water. “Liquoring” a soap consists in adding 5 to 25 per cent. of soluble silicates. By this means the soap may be made to hold 70 per cent. of water, which is obviously very wasteful.

In washing the skin, the water washes away a considerable amount of epidermis, and the saline matters which have collected. For the oily sebaceous secretion soap is required. The alkali in soap combines with the oily matter, forming an emulsion which carries away with it a quantity of the dirt which previously blocked the orifices of the sebaceous and sweat ducts. When the skin is rubbed by the towel after washing, the softened epithelium, and with it any remaining dirt, are rubbed off, leaving the skin clean, and able to perform its normal functions.

=The Use of Baths.=—The primary object of bathing is cleanliness. A secondary consideration is the pleasure derived from bathing. Baths are especially necessary for those persons who lead sedentary lives. When the skin is kept in an active condition by exercise, it to some extent cleanses itself. Thus, a farm labourer who has a weekly bath, may be really cleaner than a person of sedentary habits, who has two baths per week.

Baths are classified according to temperature as follows:—Below 70° Fahr. they are described as _cold_; tepid up to 85°; _warm_ up to 97°; and _hot_ over this temperature. It is important in deciding the temperature of a bath not to trust to one’s sensations; the only accurate measure is by the thermometer. A cold morning tub in the summer will commonly contain water at 55° to 60°; while the same in winter will be down to 40°, or occasionally to 32°.

For purposes of cleanliness the _warm bath_ is the most efficient, combined with the free use of soap. The chief objection to it is that it produces an increased flow of blood to the skin, by relaxing the cutaneous blood-vessels, thus increasing the danger of chills if there is subsequent exposure. The increased sensibility to cold resulting from a warm bath may be obviated by afterwards rapidly sponging the body all over with cold water, and then drying the body quickly, and using the friction of a moderately rough towel. It is desirable for both cold and warm baths to have a “bath-sheet,” in which the person may be completely enclosed on coming out of the bath. Drying is thus much more quickly accomplished, and the danger of chill is minimised.

A daily morning _cold bath_ is a most important agent in the maintenance of robust health. The first sensation on entering a cold bath is of shock, due to the cooling of the surface of the body. This is followed in a few seconds by a glow, due to the blood returning with considerable force to the skin. A cold bath ought to be taken as rapidly as possible. If soaping the body is desired, it should be done before entering the bath, and the stay in the latter should be little more than momentary. In this way the best reaction or “glow” is obtained.

If a feeling of cold and chilliness remains after a cold bath, it has done more harm than good. This condition may often be avoided by quick drying and brisk friction; if after this a good reaction is not obtained, the temperature of the water should be increased. For those who are not very robust, the “cold tub” in winter is to be deprecated. If the water be raised to 60° by the addition of warm water, or in some cases even to 70°, a good reaction may be obtained. In other cases, in which a reaction is not experienced even after a bath of the latter temperature, a tepid bath may be taken, and then the body rapidly sponged with colder water.

Cold baths increase the tone of the skin, rendering it less susceptible to changes of temperature. The tendency to “catch cold” is diminished, the blood-vessels and nerves of the skin both responding more readily to any stimuli.

_Swimming_ is a valuable combination of bathing and exercise. A sudden plunge into cold water for swimming purposes is dangerous to those who are not hardened to it, and especially so in the case of running water, as in rivers or the sea. Here the water around the swimmer is constantly being changed, and each layer of water coming in contact with him abstracts a considerable amount of heat. Many of the cases of so-called death from “cramp” are really due to the benumbing and depressing influence of continued cold on the vital organs.

Swimming, under proper superintendence, ought to be universally enforced. The exercise accompanying it serves in most cases to counteract the depressing action of the cold water; but it is important in all cases to attend to certain rules. The immersion should not be prolonged; the body should be warm at the time of entering the water; and the bath should not be taken until about two hours after a meal; nor after prolonged fasting, as before breakfast.

=Personal Cleanliness.=—Personal cleanliness involves not only attention to the skin, which we have already considered, but to the hair, nails, mouth, and other parts of the body.

The _hair_ ought to be carefully brushed and combed, but it is not desirable to use soap to it as often as to the skin. Soap removes the sebaceous secretion from the hairs, and renders them dry and brittle. Artificial pomades are, as a rule, unnecessary.

The _nails_ should be cut square, and not down at the sides. It is hardly necessary to say that they should be kept clean: they may convey serious infection.

The _mouth_ and all mucous orifices should be kept scrupulously clean. A fœtid breath is not uncommonly due to the discharges from carious teeth, or to the decomposition of food which has been allowed to accumulate in the cavities of teeth. Such decomposing matters when swallowed, are apt to produce indigestion; and this also occurs from imperfect mastication of food by the bad teeth. It is important that the _teeth_ should be frequently cleansed, and that all carious teeth should be “stopped” at an early period, and tartar and other accumulations removed. Whether bad teeth, which are so extremely common, are due to the drinking of very hot liquids, or to the fact that the more perfect cooking of food gives less healthy friction to the teeth, is doubtful. Whatever the cause, by keeping the mouth thoroughly sweet and clean, and by having the carious teeth stopped as soon as discovered, their vitality may be greatly prolonged. Teeth should be periodically inspected by a competent dentist. Irregularities of the teeth may be corrected, if they receive early attention. Carious “milk-teeth” should receive attention from a dentist, as well as the permanent teeth.

=General Cleanliness.=—Next to cleanliness of the skin, that of the _apparel_ is most important.

There is a general preference for colours “that do not show the dirt”; the fact that it is still there, though not seen, being partially ignored. Changing of apparel is commonly confined to underclothing. It is forgotten that vests, trousers, dresses, etc., acquire a large amount of dirt and organic matter, and ought to be changed and well aired at intervals.

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.