CHAPTER VI.. Animal Heat.

ANIMAL HEAT.

Q. What is the cause of ANIMAL HEAT?

A. Animal heat is produced by the combustion of hydrogen and carbon in the capillary veins.

Q. What are CAPILLARY VEINS?

A. Veins as small as hairs running all over the body; so called from the Latin word "capilla'ris" (like a hair).

Q. Do these CAPILLARY VEINS run all over the human body?

A. Yes. Whenever blood flows from a wound, some vein must be divided; and as you cannot insert a needle into any part of the body without bringing blood, therefore these little veins must run through every part of the human frame.

Q. How do HYDROGEN gas and CARBON get into these very little veins?

A. The food we eat is converted into blood, and blood contains both hydrogen and carbon.

Q. How does COMBUSTION take place in the veins?

A. The carbon of the blood combines with the oxygen of the air we breathe, and forms into carbonic acid gas.

Q. What BECOMES of this CARBONIC ACID GAS formed in the human blood?

A. Some of it is thrown off by the breath; and the rest of it is absorbed by the blood, to keep up the animal heat.

Q. What is the cause of the COMBUSTION of FIRE?

A. The carbon of fuel unites with the oxygen of the air, and forms carbonic acid gas.

Q. What is the cause of the COMBUSTION of a CANDLE or LAMP?

A. The carbon of the oil or tallow unites with the oxygen of the air, and forms carbonic acid gas.

Q. What is the cause of SPONTANEOUS COMBUSTION?

A. The piled-up goods ferment from heat and damp; and (during fermentation) carbonic acid gas is formed, as in the two former cases.

Q. Does the HEAT of the HUMAN BODY arise from the SAME CAUSE as the heat of FIRE?

A. Yes, precisely. The carbon of the blood, combining with the oxygen of air inhaled, produces carbonic acid gas, which is attended with combustion.

Q. If animal heat is produced by COMBUSTION, why does not the human body BURN UP like a coal or candle?

A. It actually does so. Every muscle, nerve, and organ of the body, actually wastes away like a burning candle; and (being reduced to air and ashes) is rejected from the system as useless.

Q. If every bone, muscle, nerve, and organ, is thus consumed by combustion, why is not the BODY entirely CONSUMED?

A. It would be so, unless the parts destroyed were perpetually renewed: but as a lamp will not go out, so long as it is supplied with fresh oil; neither will the body be consumed, so long as it is supplied with sufficient food.

Q. When a man is STARVED, what parts of the body go first?

A. First the fat, because it is the most combustible; then the muscles; last of all the brain; and then the man dies, like a candle which is burnt out.

Q. Why does WANT of sufficient NOURISHMENT often produce MADNESS?

A. After the fat and muscles of the body have been consumed by animal combustion, the brain is next attacked; and (unless the patient dies) madness must ensue from starvation.

Q. Why does a man SHRINK when STARVED?

A. A starved man shrinks just as a fire does, unless it be supplied with sufficient fuel.

Q. What is the FUEL of the BODY?

A. Food is the fuel of the body; and the carbon of the food mixing with the oxygen of the air, evolves heat in the same way that a fire or candle does.

Q. Why is EVERY part of the BODY WARM?

A. As the capillary veins run through every part of the human body, and the combustion of blood takes place in the capillary veins, therefore every part of the body is warm.

Q. Why does RUNNING make us WARM?

A. When we run, we inhale air more rapidly; and the rapidity with which we inhale air fans the combustion of our body, as a pair of bellows quickens the flame of a common fire.

Q. How does INHALING AIR RAPIDLY make the body feel WARM?

A. As the combustion of the blood is more rapid, (in consequence of the introduction of more oxygen from the air), therefore the blood is more heated, and every part of the body is warmer also.

Q. Why does HARD WORK produce HUNGER?

A. Because it produces quicker respiration; by which means a larger amount of oxygen is introduced into the lungs, and the capillary combustion increased. Hunger is the notice (given by our body) to remind us, that our food-fuel must be replenished.

Q. Why does SINGING make us HUNGRY?

A. Singing increases respiration; and as more oxygen is introduced into the lungs, our food-fuel is more rapidly consumed.

Q. Why does READING ALOUD make us feel HUNGRY?

A. Reading aloud increases respiration; and as more oxygen is introduced into the lungs, our food-fuel is more rapidly consumed.

Q. Why do we feel MORE HUNGRY in the DAY-TIME than in the NIGHT-TIME?

A. As we breathe more slowly during sleep, therefore, less oxygen is introduced into the lungs to consume our food-fuel.

Q. Why do we need WARMER CLOTHING by NIGHT than by DAY?

A. 1st--Because the night is generally colder than the day.

2ndly--As our respiration is slower, our animal combustion is slower also; in consequence of which, our bodies are more cold.

Q. Why do we PERSPIRE when very HOT?

A. The pores of the body are like the safety valves of a steam-engine; when the heat of the body is too great, the combustible gas and grease flow out in perspiration, instead of burning in the blood.

Q. Why do persons feel LAZY and averse to exercise, when they are HALF-STARVED or ILL-FED?

A. Animal food contains great nourishment, and produces a desire for active occupations; but when the body is not supplied with strong food, this desire for muscular action ceases, and the person grows slothful.

Q. Why have persons, who follow HARD OUT-OF-DOORS OCCUPATIONS, more APPETITE than those who are engaged in SEDENTARY pursuits?

A. Hard bodily labour in the open air causes much oxygen to be conveyed into the lungs by inspiration; the combustion of the food is carried on quickly; animal heat increased; and need for nutritious food more quickly indicated by craving hunger.

Q. Why have persons who follow SEDENTARY PURSUITS less APPETITE than ploughmen and masons?

A. 1st--The air they inhale is not so pure, because its oxygen is partly exhausted: and

2ndly--Their respiration is neither so quick nor strong, and therefore the combustion of their food is carried on more slowly.

Q. Why do we like strong MEAT and GREASY food when the WEATHER is very COLD?

A. Strong meat and grease contain large portions of hydrogen, which (when burned in the blood) produce a larger amount of heat than any other kind of food.

Q. Why do persons EAT MORE food in COLD weather, than in hot?

A. In cold weather the body requires more fuel to keep up the same amount of animal heat; and as we put more coals on a fire on a cold day to keep our room warm, so we eat more food on a cold day to keep our body warm.

Q. Why does COLD produce HUNGER?

A. 1st--The air contains more oxygen in cold weather; and as fires burn fiercer, so animal combustion is more rapid: and

2ndly--We are more active in cold weather; and increased respiration acts like a pair of bellows on the capillary combustion.

Q. Why does rapid DIGESTION produce a craving APPETITE?

A. This is a wise providence to keep our bodies in health; in order that the body itself may not be consumed, it gives notice (by hunger) that the capillary fires need replenishing.

Q. Why do we feel a desire for ACTIVITY in cold weather?

A. 1st--Because activity increases the warmth of the body, by fanning the combustion of the blood: and

2ndly--The strong food we eat creates a desire for muscular exertion.

Q. Why are the Esquimeaux so passionately fond of TRAIN OIL and WHALE BLUBBER?

A. Oil and blubber contain a very large amount of hydrogen, which is exceedingly combustible; and as these people live in climates of intense cold, the heat of their bodies is increased by the greasy nature of their food.

Q. Why do we feel a dislike to strong meat and greasy foods in very hot weather?

A. Strong meat and grease contain so much hydrogen, that they would make us intensely hot; and therefore we refuse them in hot weather.

Q. Why do we like fruits and vegetables so very much in hot weather?

A. Fruits and vegetables contain less carbon than meat, and therefore produce less blood: instead of blood, they combine into water as they are digested, and keep the body cool.

Q. Why do people say that FRUITS and VEGETABLES COOL the BLOOD?

A. 1st--Because they deprive the blood of carbon, which is the chief cause of animal heat: and

2ndly--These gases coalesce into water, which greatly tempers the animal heat.

Q. Why do we feel LAZY and averse to activity in very HOT WEATHER?

A. 1st--Because muscular activity would increase the heat of the body, by quickening the respiration: and

2ndly--The food we eat in hot weather, not being greasy, naturally abates our desire for bodily activity.

Q. Why do the inhabitants of tropical countries live chiefly upon rice and fruit?

A. Rice and fruit by digestion are mainly converted into water, and (by cooling the blood) prevent the tropical heat from feeling so oppressive.

Q. Why are POOR PEOPLE generally AVERSE to CLEANLINESS?

A. 1st--Cleanliness increases hunger; and as poor people are generally ill-fed, they are averse to cleanliness.

2ndly--Dirt is warm, (thus pigs who love warmth, are fond of dirt); and as poor people are generally ill-clad, they like the warmth of dirt.

Q. Why are POOR PEOPLE generally AVERSE to VENTILATION?

A. 1st--Because ventilation increases the oxygen of the air,--the combustion of food,--and the cravings of appetite: and

2ndly--Ventilation cools the air of our rooms: poor people, therefore, (who are generally ill-clad) love the warmth of an ill-ventilated apartment.

Q. Why does FLANNEL, &c. make us WARM?

A. Flannel and warm clothing do not make us warm, but merely prevent the body from becoming cold.

Q. How does flannel, &c. prevent the body from becoming cold?

A. Flannel (being a bad conductor) will neither carry off the heat of the body into the cold air, nor suffer the cold of the air to come into contact with our warm bodies; and thus it is that flannel clothing keeps us warm.

Q. Why are FROGS and FISHES COLD-BLOODED animals?

A. Because they consume so little air; and without a plentiful supply of air, combustion is so slow, that very little animal heat is evolved.

Q. Why is a DEAD BODY COLD?

A. Air is no longer conveyed to the lungs after respiration has ceased; and, therefore, animal heat is no longer evolved by combustion.