The lungs are supplied with more blood than any other, part of the body. A small part of it is for the nourishment of the lung structure, but most of it comes to be purified. After the blood has traveled to various parts of the body to perform its work as a carrier of food, and oxygen and gatherer of waste, it returns to the heart and from the heart it is sent to the lungs. There it gives up its carbonic acid gas and receives a supply of oxygen. Then it returns to the heart again and once more it is sent to all parts of the body to distribute the vital element, oxygen.
The lungs give off watery vapor, a little animal matter and considerable heat, but their chief function is to exchange the carbonic acid gas of the blood for the oxygen of the air. When the fats, sugars and starches, in their modified form, are burned in the body to produce heat and energy, carbonic acid gas and water are formed. The gas is taken up by the blood stream, which is being deprived of its oxygen at the same time. This exchange turns the blood from red into a bluish tinge. The red color is due to the union of oxygen with the iron in the blood corpuscles, forming rust, roughly speaking.
The fine adjustment that exists in nature can be seen by taking into consideration that animals give off carbon dioxide and breathe in oxygen, while vegetation exhales oxygen and inhales carbon dioxide. In other words, animal life makes conditions favorable for plant growth, and vegetation makes possible the existence of animals.
An animal of the higher class can live several days without water, several weeks without food, but only a very few minutes without oxygen. When the blood becomes surcharged with carbonic acid gas, and oxygen is refused admittance to the lungs, life ceases in about five or six minutes. From this it can easily be seen how important it is to have a proper supply of oxygen. Acute deprivation of this element is immediately fatal, and chronic deprivation of a good supply helps to produce early deterioration and premature death. The lungs can easily be kept in good condition, and when we ponder on the beautiful and effective way in which nature has equipped us with a respiratory apparatus and an inexhaustible store of oxygen, surely we must understand the folly of not helping ourselves to what is so vital, yet absolutely free.
Wrong eating and impure air are largely responsible for all kinds of respiratory troubles, from a simple cold to the most aggravated form of pulmonary tuberculosis. Exercise and deep breathing will to a great extent antidote overeating, but there is a limit beyond which the lungs refuse to tolerate this form of abuse.
Experiments have shown that if the carbonic acid gas thrown off daily by an adult male were solidified, it would amount to about seven ounces of solid carbon, which comes from fats, sugars and starches that are burned in the body. It is well to remember that there are various forms of burning or combustion. Rapid combustion is exemplified in stoves and furnaces, where the carbon of coal or wood rapidly and violently unites with oxygen. Slow combustion takes place in the rotting of wood, the rusting of iron and steel and the union of oxygen with organic matter in animal bodies. Both processes are the same, varying only in rapidity and intensity.
People who daily give off seven ounces of carbon are overworking their bodies. They take in too much food and consequently force too great combustion. This forcing has evil effects on the system, for under forced combustion the body is not able to clean itself thoroughly. Some of the soot remains in the flues (the blood-vessels) and is deposited in the various parts of the engine (the body). Result: Hardening, which means loss of elasticity and aging of the body. Aging of the body results in deterioration of the mind. Proper breathing is fine, but unless it is also accompanied by proper eating it does not bring the best results.
The atmospheric air contains about four parts of carbonic acid gas to 10,000 parts of air. The exhaled air becomes quite heavily charged with this gas, about 400 to 500 parts in 10,000. It does not take long before the air in a closed, occupied room is so heavily charged with this gas and so poor in oxygen that its constant rebreathing is detrimental. The blood stream becomes poisoned, which immediately depresses the physical and mental powers. Warning is often given by a feeling of languor and perhaps a slight headache. People accustom themselves to impure air so that they apparently feel no bad effects, but this is always at the expense of health. The senses may be blunted, but the evil results always follow. To keep a house sealed up as tightly as possible in order to keep it warm saves fuel bills, but the resultant bodily deterioration and disease cause enough discomfort and result in doctor bills which more than offset this saving. It is poor economy.
A constant supply of the purest air obtainable must be furnished to the lungs; otherwise the blood becomes so laden with poison that health, in its best and truest sense, is impossible.
The air should be inhaled through the nose. It does not matter much how it is exhaled. The nose is so constructed that it fits the air for the lungs. The inspired air is often too dry, dusty and cold. The normal nose remedies all these defects. The mucous membrane in the nasal passages contains cilia, which catch the dust. The nasal passages are very tortuous so that during its journey through them the air is warmed and takes up moisture.