HYGIENE DEFINED.—PURE AIR.

The object of hygiene is the preservation of health. Hitherto, we have considered, at some length, the science of functions, or Physiology, and now, under the head of Hygiene, we will give an outline of the means of maintaining the functional integrity of the system. It is difficult to avoid including under this head Preventive Medicine, the special province of which is to abate, remove, or destroy the many causes of disease.

The Greeks bestowed divine honors upon Aesculapius, because he remedied the evils of mankind and healed the sick. The word hygiene is derived from Hygeia, the name of the Greek goddess of health. As male and female are made one in wedlock, so Medicine and Hygiene, restoration and preservation, are inseparably united.

Hygiene inculcates sanitary discipline, medicine, remedial discipline; hygiene prescribes healthful agencies, medical theory and practice, medicinal agencies; hygiene ministers with salubrious and salutary agents, medicine assuages with rectifying properties and qualities; hygiene upholds and sustains, medical practice corrects and heals; the one is preservative and conservative, the other curative and restorative. These discriminations are as radical as health and sickness, as distinct as physiology and pathology, and to confound them is as unnatural as to look for the beauties of health in the chamber of sickness.

The true physician brings to his aid Physiology, Hygiene, and Medicine, and combines the science of the former with the art of the latter, that restoration may be made permanent, and the health preserved by the aid of hygiene. But when any one makes Hygiene exclusively the physician, or deals wholly in hygienic regulations with little respect for physiology, or lavishly advertises with hygienic prefixes, we may at once consider it a display, not of genuine scientific knowledge, but only of the ignorance of a quack. Some of the modern twaddle about health is a conglomeration of the poorest kind of trash, expressing and inculcating more errors and whims than it does common sense. Many persons dilate upon these subjects with amazing flippancy, their mission seeming to be to traduce the profession rather than to act as help-mates and assistants. We do not believe that there is any real argument going on between the educated members of the medical profession but rather that the senseless clamor we occasionally hear comes only from the stampede of some routed, demoralized company of quacks.

In the following pages we shall introduce to the reader's attention several important hygienic subjects, although there are many more that ought to receive special notice. Such as we do mention, demand universal attention, because a disregard of the conditions which we shall enumerate, is fraught with great danger. Our lives are lengthened or shortened by the observance or neglect of the rules of common sense, and these do not require any great personal sacrifice, or the practice of absurd precautions.

PURE AIR FOR RESPIRATION.

Ordinary atmospheric air contains nearly 2,100 parts of oxygen and 7,900 of nitrogen, and about three parts of carbonic acid, in 10,000 parts; expired air contains about 470 parts of carbonic acid, and only between 1500 and 1600 parts of oxygen, while the quantity of nitrogen undergoes little or no alteration. Thus air which has been breathed has lost about five per cent. of oxygen and has gained nearly five per cent. of carbonic acid. In addition the expired air contains a greater or less quantity of highly decomposable animal matter, and, however dry the atmospheric air may be, the expired air is always saturated with watery vapor, and, no matter what the temperature of the external air may be, that of the exhaled air is always nearly as warm as the blood. An adult man on a average breathes about sixteen times in a minute and at every inspiration takes in about thirty cubic inches of air, and at every expiration exhales about the same amount. Hence, it follows that about 16-2/3 cubic feet of air are passed through the lungs of an adult man every hour, and deprived of oxygen and charged with carbonic acid to the amount of nearly five per cent. The more nearly the composition of the external air approaches that of the expired air, the slower will be the diffusion of carbonic acid outwards and of oxygen inwards, and the more charged with carbonic acid and deficient in oxygen will the blood in the lungs become. Asphyxia takes place whenever the proportion of carbonic acid in the external air reaches ten per cent., providing the oxygen is diminished in like proportion, and it does not matter whether this condition of the external air is produced by shutting out fresh air from a room or by increasing the number of persons who are consuming the same air; or by permitting the air to be deprived of oxygen by combustion by a fire. A deficiency of oxygen and an accumulation of carbonic acid in the atmosphere, produce injurious effects, however, long before the asphyxiating point is attained. Headache, drowsiness, and uneasiness occur when less than one per cent. of the oxygen of the atmosphere is replaced by other matters, and the constant breathing of such an atmosphere lowers vitality and predisposes to disease.

Therefore, every human being should be supplied, by proper ventilation, with a sufficient supply of fresh air. Every adult individual ought to have at least 800 cubic feet of air-space to himself, and this space ought to communicate freely with the external atmosphere by means of direct or indirect channels. Hence, a sleeping-room for one adult person should not be less than nine by ten feet in breadth and length and nine feet in height. What occurred in the Black Hole at Calcutta is an excellent illustration of the effect of vitiated air. One hundred and forty-six Englishmen were confined in a room eighteen feet square, with two small windows on one side to admit air. Ten hours after their imprisonment, only twenty-three were alive.

Ventilation of School Rooms. The depression and faintness from which many students suffer, after being confined in a poorly ventilated school room, is clearly traceable to vitiated air, while the evil is often ascribed to excessive mental exertion. The effect of ventilation upon the health of students is a subject of universal interest to parents and educators, and at present is receiving the marked attention of school authorities. Dr. F. Windsor, of Winchester, Mass., made a few pertinent remarks upon this subject in the annual report of the State Board of Health, of Massachusetts, 1874. One of the institutions, which was spoken of in the report of 1873, as a model, in the warming and ventilation of which much care had been bestowed, was visited in December, 1873. He reports as follows: "I visited several of the rooms, and found the air in all, offensive to the smell, the odor being such as one would imagine old boots, dirty clothes, and perspiration would make if boiled down together; again, in the new model school-house the hot air enters at two registers in the floor on one side, and makes (or is supposed to make) its exit by a ventilator at the floor, on the other side of the room." The master said "the air was supposed to have some degree of intelligence, and to know that the ventilator was its proper exit." Thorough ventilation has been neglected by many school officials on account of the increased expense it causes. In our climate, during seven months at least, pure atmospheric air must be paid for. The construction of vertical ducts, the extra amount of fuel, and the attendant expenditures are the objections which, in the opinion of many persons, outweigh the health and happiness of the future generation. It is necessary for the proper ventilation of our school rooms that an adequate supply of fresh air should be admitted, which should be warmed before being admitted to the room, and which should be discharged as contaminated, after its expiration. The proper ventilation of the school room consists in the warming and introduction of fresh air from without, and the discharge of the expired and unwholesome air from within. This may be accomplished by means of doors, windows, chimneys, and finally by ventilators placed, one near the level of the floor, and the other near the ceiling of the room. The ventilators ought to be arranged on the opposite sides of the room, in order to insure a current, and an abundant supply of air. When trustees and patrons realize that pure air is absolutely essential to health, and that their children are being slowly poisoned by the foul air of school rooms, then they will construct our halls of learning with a due regard for the laws of hygiene, and students will not droop under their tasks on account of the absence of Nature's most bountiful gift, pure air.