Another requisite to the well-being of the lungs, and to the free and salutary exercise of respiration, is a due supply of rich and healthy blood. When, from defective food or impaired digestion, the blood is impoverished in quality, and rendered unfit for adequate nutrition, the lungs speedily suffer, and that often to a fatal extent. The free and easy expansion of the chest is also indispensable to the full play and dilation of the lungs. Whatever interferes with or impedes it, either in dress or in position, is obviously prejudicial to health. On the other hand, whatever favors the free expansion of the chest equally promotes the healthy action of the respiratory organs. Stays and corsets, and tight vests and waistbands, operate most injuriously, compressing as they do the thoracic cavity, and interfering with the healthy dilation of the lungs.

The admirable harmony established by the Creator between the various const.i.tuent parts of the animal frame, renders it impossible to pay regard to the conditions required for the health of any one, or to infringe the conditions required therefor, without all the rest partic.i.p.ating in the benefit or injury. Thus, while cheerful exercise in the open air and in the society of equals is directly and eminently conducive to the well-being of the muscular system, the advantage does not stop there, the beneficent Creator having kindly so ordered it that the same exercise shall be scarcely less advantageous to the important function of respiration. Active exercise calls the lungs into play, favors their expansion, promotes the circulation of the blood through their substance, and leads to their complete and healthy development.

The same end is greatly facilitated by that free and vigorous exercise of the voice, which so uniformly accompanies and enlivens the sports of the young, and which doubles the benefits derived from them considered as exercise. The excitement of the social and moral feelings which children experience while engaged in play is another powerful tonic, the influence of which on the general health ought not to be overlooked; for the nervous influence is as indispensable to the right performance of respiration as it is to the action of the muscles or to the digestion of food.

The regular supply of pure fresh air is another essential condition of healthy respiration, without which the requisite changes in the const.i.tution of the blood, as it pa.s.ses through the lungs, can not be effected. To enable the reader to appreciate this condition, it is necessary to consider the nature of the changes alluded to.

It is ascertained by a.n.a.lysis that the air we breathe is composed chiefly of the two gases _nitrogen_ and _oxygen_, united in the ratio of four to one by volume, with exceedingly small and variable quant.i.ties of carbonic acid and aqueous vapor. No other mixture of these, or of any other gases, will sustain healthy respiration. To be more specific--atmospheric air consists of about seventy-eight per cent. of nitrogen, twenty-one per cent. of oxygen, and not quite one per cent. of carbonic acid. Such is its const.i.tution when taken into the lungs in the act of breathing. When it is expelled from them, however, its composition is found to be greatly altered. The quant.i.ty of nitrogen remains nearly the same, but eight or eight and a half per cent. of the oxygen or vital air have disappeared, and been replaced by an equal amount of carbonic acid. In addition to these changes, the expired air is loaded with moisture. Simultaneously with these occurrences, the blood collected from the veins, which enters the lungs of a dark color and unfit for the support of life, a.s.sumes a florid hue and acquires the power of supporting life.

Physiologists are not fully agreed in explaining the processes by which these changes are effected in the lungs. All, however, agree that the change of the blood in the lungs is essentially dependent on the supply of oxygen contained in the air we breathe, and that air is fit or unfit for respiration in exact proportion as its quant.i.ty of oxygen approaches to, or differs from, that contained in pure air. If we attempt to breathe nitrogen, hydrogen, or any other gas that does not contain oxygen, the result will be speedy suffocation. If, on the other hand, we breathe air containing too great a proportion of oxygen, the vital powers will speedily suffer from excess of stimulus.

The chief chemical properties of the atmosphere are owing to the presence of _oxygen_. Nitrogen, which const.i.tutes about four fifths of its volume, has been supposed to act as a mere diluent to the oxygen.

_Increase_ the proportion of oxygen in the atmosphere, and, as already stated, the vital powers will speedily suffer from excess of stimulus, the circulation and respiration become _too rapid_, and the system generally becomes highly excited. _Diminish_ the proportion of oxygen, and the circulation and respiration become _too slow_, weakness and la.s.situde ensue, and a sense of heaviness and uneasiness pervades the entire system. As has been observed, air _loses_ during each respiration a portion of its oxygen, and gains an equal quant.i.ty of _carbonic acid_, which is an _active poison_. When mixed with atmospheric air in the ratio of one to four, it extinguishes animal life. It is this gas that is produced by burning charcoal in a confined portion of common air. Its effect upon the system is well known to every reader of our newspapers.

It causes dimness of sight, weakness, dullness, a difficulty of breathing, and ultimately _apoplexy_ and _death_.[12]

[12] Since the text was prepared for the press, I have noticed from the Syracuse (New York) Journal of January 3d, 1850, mention of the death of General Rensselaer Van Rensselaer, of that city, from breathing "the fumes of charcoal" burned in a "portable furnace." This, it should be remembered, is but _one_ of the _many instances_ that are constantly occurring all over our country, in which _immediate death_ is the result of breathing this destructive agent.

Respiration produces the same effect upon air that the burning of charcoal does. It converts its oxygen, which is the aliment of animal life, into carbonic acid, which, be it remembered, is an active poison.

Says Dr. Turner, in his celebrated work on chemistry, "An animal can not live in air which is unable to support combustion." Says the same author again, "An animal can not live in air which contains sufficient carbonic acid for extinguishing a candle." It will presently be seen why these quotations are made.

It is stated in several medical works that the quant.i.ty of air that enters the lungs at each inspiration of an adult varies from thirty-two to forty cubic inches. To establish more definitely some data upon which a calculation might safely be based, I some years ago conducted an experiment whereby I ascertained the medium quant.i.ty of air that entered the lungs of myself and four young men was thirty-six cubic inches, and that respiration is repeated once in three seconds, or twenty times a minute. I also ascertained that _respired air will not support combustion_. This truth, taken in connection with the quotations just made, establishes another and a _more important_ truth, viz., that AIR ONCE RESPIRED WILL NOT FURTHER SUSTAIN ANIMAL LIFE. That part of the experiment by which it was ascertained that respired air will not support combustion is very simple, and I here give it with the hope that it may be tried at least in every _school-house_, if not in every family of our wide-spread country. It was conducted as follows:

I introduced a lighted taper into an inverted receiver (gla.s.s jar) which contained seven quarts of atmospheric air, and placed the mouth of the receiver into a vessel of water. The taper burned with its wonted brilliancy about a minute, and, growing dim gradually, became extinct at the expiration of three minutes. I then filled the receiver with water, and inverting it, placed its mouth beneath the surface of the same fluid in another vessel. I next removed the water from the receiver by _breathing into it_. This was done by filling the lungs with air, which, after being retained a short time in the chest, was exhaled through a siphon (a bent lead tube) into the receiver. I then introduced the lighted taper into the receiver of respired air, by which it was _immediately extinguished_. Several persons present then received a quant.i.ty of respired air into their lungs, whereupon the premonitory symptoms of apoplexy, as already given, ensued. The experiment was conducted with great care, and several times repeated in the presence of respectable members of the medical profession, a professor of chemistry, and several literary gentlemen, to their entire satisfaction.

Before proceeding further, I will make a practical application of the principles already established. Within the last ten years I have visited half of the states of the Union for the purpose of becoming acquainted with the actual condition of our common schools. I have therefore noticed especially the condition of school-houses. Although there is a great variety in their dimensions, yet there are comparatively few school-houses less than sixteen by eighteen feet on the ground, and fewer still larger than twenty-four by thirty feet, exclusive of our princ.i.p.al cities and villages. From a large number of actual measurements, not only in New York and Michigan, but east of the Hudson River and west of the great lakes, I conclude that, exclusive of entry and closets, when they are furnished with these appendages, school-houses are not usually larger than twenty by twenty-four feet on the ground, and seven feet in height. They are, indeed, more frequently smaller than larger. School-houses of these dimensions have a capacity of 3360 cubic feet, and are usually occupied by at least forty-five scholars in the winter season. Not unfrequently sixty or seventy, and occasionally more than a hundred scholars occupy a room of this size.

A simple arithmetical computation will abundantly satisfy any person who is acquainted with the composition of the atmosphere, the influence of respiration upon its fitness to sustain animal life, and the quant.i.ty of air that enters the lungs at each inspiration, that a school-room of the preceding dimensions contains quite too little air to sustain the healthy respiration of even _forty-five_ scholars three hours--the usual length of each session; and frequently the school-house is imperfectly ventilated between the sessions at noon, and sometimes for several days together.

Mark the following particulars: 1. The quant.i.ty of air breathed by forty-five persons in three hours, according to the data just given, is 3375 cubic feet. 2. _Air once respired will not sustain animal life._ 3.

The school-room was estimated to possess a capacity of 3360 cubic feet--_fifteen feet less than is necessary to sustain healthy respiration_. 4. Were forty-five persons whose lungs possess the estimated capacity placed in an air-tight room of the preceding dimensions, and could they breathe pure air till it was all once respired, and then enter upon its second respiration, _they would all die with the apoplexy before the expiration of a three hours' session_.

From the nature of the case, these conditions can not conveniently be fulfilled. But numerous instances of fearful approximation exist. We have no air-tight houses. But in our lat.i.tude, comfort requires that rooms which are to be occupied by children in the winter season, be made very close. The dimensions of rooms are, moreover, frequently narrowed, that the _warm breath_ may lessen the amount of fuel necessary to preserve a comfortable temperature. It is true, on the other hand, that the quant.i.ty of air which children breathe is somewhat less than I have estimated. But the derangement resulting from breathing impure air, in their case, is greater than in the case of adults whose const.i.tutions are matured, and who are hence less susceptible of injury. It is also true in many schools that the number occupying a room of the dimensions supposed is considerably greater than I have estimated. Moreover, in many instances, a great proportion of the larger scholars will respire the estimated quant.i.ty of air.

Again, all the air in a room is not respired _once_ before a portion of it is breathed the second, or even the _third_ and _fourth_ time. The atmosphere is not suddenly changed from purity to impurity--from a healthful to an infectious state. Were it so, the change, being more perceptible, would be seen and _felt_ too, and a _remedy_ would be sought and applied. But because the change is gradual, it is not the less fearful in its consequences. In a room occupied by _forty-five persons_, THE FIRST MINUTE, _thirty-two thousand four hundred cubic inches of air impart their entire vitality to sustain animal life, and, mingling with the atmosphere of the room, proportionately deteriorate the whole ma.s.s_. Thus are abundantly sown in early life the fruitful seeds of disease and premature death.

This detail shows conclusively sufficient cause for that uneasy, listless state of feeling which is so prevalent in crowded school-rooms.

It explains why children that are amiable at home are mischievous in school, and why those that are troublesome at home are frequently well-nigh uncontrollable in school. It discloses the true cause why so many teachers who are justly considered both pleasant and amiable in the ordinary domestic and social relations, are obnoxious in the school-room, being there habitually sour and fretful. The ever-active children are disqualified for study, and engage in mischief as their only alternative. On the other hand, the irritable teacher, who can hardly look with complaisance upon good behavior, is disposed to magnify the most trifling departure from the rules of propriety. The scholars are continually becoming more ungovernable, and the teacher more unfit to govern them. Week after week they become less and less attached to him, and he, in turn, becomes less interested in them.

This detail explains, also, why so many children are unable to attend school at all, or become unwell so soon after commencing to attend, when their health is sufficient to engage in other pursuits. The number of scholars answering this description is greater than most persons are aware of. In one district that I visited a few years ago in the State of New York, it was acknowledged by competent judges to be emphatically true in the case of not less than _twenty-five scholars_. Indeed, in that same district, the health of more than _one hundred_ scholars was materially injured every year in consequence of occupying an old and partially-decayed house, of too narrow dimensions, with very limited facilities for ventilation. The evil, even after the cause was made known, was suffered to exist for years, although the district was worth more than three hundred thousand dollars. And what _was_ true[13] of this school, is now, with a few variations, true in the case of scores, if not hundreds of schools with which I am acquainted, from far-famed New England to the Valley of the Mississippi.

[13] In the district referred to there has since been erected a large and commodious union school house, which const.i.tutes at once the pride and ornament of a beautiful and flourishing village.

This detail likewise explains why the business of teaching has acquired, and _justly too_, the reputation of being unhealthy. There is, however, no reason why the health of either teacher or pupils should sooner fail in a well-regulated school, taught in a house properly constructed, and suitably warmed and ventilated, than in almost any other business. If this statement were not true, an unanswerable argument might be framed against the very _existence_ of schools; and it might clearly be shown that it is _policy_, nay, DUTY, to close at once and forever the four thousand school-houses of Michigan, and the hundred thousand of the nation, and leave the rising generation to perish for lack of knowledge.

But our condition in this respect is not hopeless. The evil in question may be effectually remedied by enlarging the house, or, which is easier, cheaper, and more effectual, by frequent and thorough ventilation. It would be well, however, to unite the two methods.

In the winter of 1841-2, I visited a school in which the magnitude of the evil under consideration was clearly developed. Five of the citizens of the district attended me in my visit to the school. We arrived at the school-house about the middle of the afternoon. It was a close, new house, eighteen by twenty-four feet on the ground--two feet less in one of its dimensions than the house concerning which the preceding calculation is made. There were present forty-three scholars, the teacher, five patrons, and myself, making fifty in all. Immediately after entering the school-house, one of the trustees remarked to me, "I believe our school-house is too tight to be healthy." I made no reply, but secretly resolved that I would sacrifice my comfort for the remainder of the afternoon, and hazard my health, and my life even, to test the accuracy of the opinions I had entertained on this important subject. I marked the uneasiness and dullness of all present, and especially of the patrons, who had been accustomed to breathe a purer atmosphere. School continued an hour and a half, at the close of which I was invited to make some remarks. I arose to do so, but was unable to proceed till I opened the outer door, and snuffed a few times the purer air without. When I had partially recovered my wonted vigor, I observed with delight the renovating influence of the current of air that entered the door, mingling with and gradually displacing the fluid poison that filled the room, and was about to do the work of death. It seemed as though I was standing at the mouth of a huge sepulcher, in which the dead were being restored to life. After a short pause, I proceeded with a few remarks, chiefly, however, on the subject of respiration and ventilation. The trustees, who had just tested their accuracy and bearing upon their comfort and health, resolved immediately to provide for ventilation according to the suggestions in the article on school-houses in the last chapter of this work.

Before leaving the house on that occasion, I was informed an evening meeting had been attended there the preceding week, which they were obliged to dismiss before the ordinary exercises were concluded, because, as they said, "We all got sick, and the candles went almost out." Little did they realize, probably, that the light of life became just as nearly extinct as did the candles. Had they remained there a little longer, both would have gone out together, and there would have been reacted the memorable tragedy of the _Black Hole_ in Calcutta, into which were thrust a garrison of one hundred and forty-six persons, one hundred and twenty-three of whom perished miserably in a few hours, being suffocated by the confined air.

What has been said in the preceding pages on the philosophy of respiration was first given to the public nearly ten years ago, in a report of the author's in the State of New York. He has since seen the same sentiments inculcated by many of our most eminent practical educators, some of whom had written upon the subject at an earlier date.

Allen and Pepy showed by experiment that air which has been once breathed contains eight and a half per cent. of carbonic acid, and that no continuance of the respiration of the same air could make it take up more than ten per cent. Air, then, when once respired, has taken up more than _four fifths_ of the amount of this noxious gas that it can be made to by any number of breathings.

Dr. Clark, in his work on Consumption, remarks as follows: "Were I to select two circ.u.mstances which influence the health, especially during the growth of the body, more than others, and concerning which the public, ignorant at present, ought to be well informed, they would be the proper adaptation of food to difference of age and const.i.tution, and the constant supply of pure air for respiration." Dr. William A. Alcott, who has given especial attention to this subject, after quoting the preceding remark of Dr. Clark, adds: "We believe this is the opinion of all medical men who have studied the const.i.tution of man, and its relation to outward objects."

A distinguished surgeon[14] of Leeds, England, goes somewhat further in praising pure air than most of his contemporaries. "Be it remembered,"

says he, "that man subsists more upon air than upon his food and drink." There is some novelty in this remark, I admit: but is it not truthful? Men have been known to live _three weeks_ without eating. But exclude the atmospheric air from the lungs for the s.p.a.ce of _three minutes_, and death generally ensues. We thus see that life will continue with abstinence from food three thousand times as long as it is safe to protract an atmospheric fast.

[14] Dr. Thackrah, author of a most valuable work on the "Effects of Employments on the Health and Longevity of Mankind."

Let us take another view of the subject. Men usually eat _three times_ in twenty-four hours. This is all that is necessary to, or compatible with, the enjoyment of uninterrupted good health. But we involuntarily breathe nearly _thirty thousand times_ in the same length of time. We need, then, fresh supplies of pure air ten thousand times as often as it is necessary to partake of meals. Is it not apparent, then, that _man subsists more upon_ AIR _than upon his_ FOOD _and_ DRINK?

The atmosphere which we so frequently inhale, and upon which our well-being so much depends, surrounds the earth to the height of about forty-five miles. The surface of the earth contains about two hundred millions of square miles, and it is estimated that there dwell upon it eight hundred millions of inhabitants. This gives to each individual about eleven cubic miles of air. But the air is breathed by the inferior animals as well as by man. It is also rendered impure by combustion. If by both of these causes ten times as much air is consumed as by man, there is still left one cubic mile of uncontaminated atmospheric air to every human being dwelling upon the surface of the earth. This would allow him to live more than twice the age allotted to man, without breathing any portion of the atmosphere a second time. And still, as if to avoid the possibility of evil to man on this account, the beneficent Creator has wisely so ordered, that while we do not interfere with the laws of Nature, there is not even the possibility of rebreathing respired air until it has been purified and restored to its natural and healthful state; for carbonic acid, the vitiating product of respiration, although immediately _fatal_ to _animals_, const.i.tutes the very _life_ of _vegetation_. When brought in contact with the upper surface of the green leaves of trees and plants, and acted upon by the direct solar rays, this gas is decomposed, and its carbon is absorbed to sustain, in part, the life of the plant, by affording it one element of its food, while the oxygen is liberated and restored to the atmosphere.

Vegetables and animals are thus perpetually interchanging kindly offices, and each flourishes upon that which is fatal to the other. It is in this way that the healthful state of the atmosphere is kept up.

Its equilibrium seems never to be disturbed, or, if disturbed at all, it is immediately restored by the mutual exchange of poison for aliment, which is constantly going on between the animal and vegetable worlds.

This interchange of kindly offices is constantly going on all over the earth, even in the highest lat.i.tudes, and in the very depths of winter; for air which has been respired is rarefied, and, when thrown from the lungs, _ascends_, and is thus not only out of our reach, whereby we are protected from respiring it a second time, but this (to us) deadly poison falls into the great aerial current which is constantly flowing from the polar to the tropical regions, where it is converted into vegetable growth. The oxygen which is exhaled in the processes of tropical vegetation, heated and rarefied by the vertical rays of the sun, mounts to the upper regions of the atmosphere, and, falling into a returning current, in its appointed time revisits the higher lat.i.tudes.

So wisely has the Divine Author ordered these processes, that air, in its natural state[15] in any part of the world, does not contain more than _one half of one per cent._ of carbonic acid gas, although, as already stated, air which has been once respired contains _eight and a half per cent._ of this gas, which is at least seventeen times its natural quant.i.ty.

[15] It would be difficult to say whether carbonic acid gas is in the atmosphere const.i.tutionally, or accidentally, or both.--_Dr. Wm. A.

Alcott's Health Tracts._

There are other agencies than carbonic acid gas which in civic life render the atmosphere impure. Of this nature is carbureted hydrogen gas, which is produced in various ways. This, says Dr. Comstock, is immediately destructive to animal life, and will not support combustion.

It exists in stagnant water, especially in warm weather, and is generated by the decomposition of vegetable products. Dr. Arnott expresses the conviction that the immediate and chief cause of many of the diseases which impair the bodily and mental health of the people, and bring a considerable portion prematurely to the grave, is the poison of atmospheric impurity, arising from the acc.u.mulation in and around their dwellings of the decomposing remnants of the substances used for food and in their arts, and of the impurities given out from their own bodies. If you allow the sources of aerial impurity to exist in or around dwellings, he continues, you are poisoning the people; and while many die at early ages of fevers and other acute diseases, the remainder will have their health impaired and their lives shortened.

There are many instances on record where the progress of an epidemic has been speedily arrested by ventilation. A striking instance is given by the writer last quoted. "When I visited Glasgow with Mr. Chadwick," says he, "there was described to us one vast lodging-house, in connection with a manufactory there, in which formerly fever constantly prevailed, but where, by making an opening from the top of each room through a channel of communication to an air-pump common to all the channels, the disease had disappeared altogether. The supply of pure air obtained by that mode of ventilation was sufficient to dilute the cause of the disease, so that it became powerless."

Sulphureted hydrogen gas is also exceedingly poisonous to the lungs and to every part of the system. When pure, this gas is described as instantly fatal to animal life. Even when diluted with fifteen hundred times its bulk of air, it has been found so poisonous as to destroy a bird in a few seconds. "This gas," says Dr. Dunglison, in his Elements of Hygiene, "is extremely deleterious.[16] When respired in a pure state it kills instantly; and its deadly agency is rapidly exerted when put in contact with any of the tissues of the body, through which it penetrates with astonishing rapidity. Even when mixed with a portion of air, it has proved immediately destructive. Dr. Paris refers to the case of a chemist of his acquaintance, who was suddenly deprived of sense as he stood over a pneumatic trough in which he was collecting this gas. From the experiments of Dupuytren and Thenard, air that contains a thousandth part of sulphureted hydrogen kills birds immediately. A dog perished in air containing a hundredth part, and a horse in air containing a fiftieth part of it."

[16] Sulphureted hydrogen gas is the deleterious agent exhaled from privies or vaults, which have been so fatal, at times, to night men, who have been employed to remove or cleanse them.--_Dr. Dunglison._

The preceding are far from being all the causes of atmospheric impurity.

Besides these, there are numerous exhalations, as well as gases, that are poisonous. Some of these exhalations are more abundant in the night, and about the time of the morning and evening twilight. "Hence the importance," says a writer on health, "to those who are feeble, of avoiding the air at all hours except when the sun is considerably above the horizon."

Although the atmosphere, in its natural state, is not at all times perfectly pure, still it is comparatively so, and especially in the daytime. All, therefore, who would retain and improve their health, should inhale the open air as much as possible, even though they can not, like Franklin's Methusalem,[17] be always in it. This remark is applicable to both s.e.xes, and to every age and condition of life.

[17] Dr. Franklin, in his usual humorous manner, but with his accustomed gravity, relates, in one of his essays, the following anecdote, for the purpose, doubtless, of showing the influence of pure air upon health, happiness, and longevity.

"It is recorded of Methusalem, who, being the longest liver, may be supposed to have best preserved his health, that he slept always in the open air; for when he had lived five hundred years, an angel said to him, Arise, Methusalem, and build thee a house, for thou shalt live yet five hundred years longer. But Methusalem answered and said, If I am to live but five hundred years longer, it is not worth while to build me a house. I will sleep in the air as I have been accustomed to do."