Sixteen to eighteen times in a minute is the ordinary rate of breathing while at rest, in health, for a grown person. In fever it is almost always a good deal faster than this; often thirty, forty, or more respirations in a minute. When a person is poisoned with opium, the breathing becomes snoring, and very slow, even only six times or less in a minute in heavy narcotism. Apoplexy, and pressure upon the brain from a piece of a broken skull, are also attended by slow, snoring respiration.

Difficulty of Breathing may be caused by irrespirable gases (as chlorine, etc.) in the air; obstruction in the air-tubes, as from croup, asthma, or bronchitis; disease of the lungs or pleura, as in pneumonia, consumption, or pleurisy; disease of the heart or aorta; abdominal dropsy, pressing upwards.

Coughing, also, may have a variety of causes, of the nature of which we may often judge by its character. Thus it is, commonly, dry and tight, in early bronchitis; soft, deep, and loose, in advanced bronchitis; hacking, in the beginning of consumption; deep and distressing, in advanced consumption; short and sharp, in pneumonia; hoarse and barking, in an early stage of croup; whistling, in advanced membranous croup; paroxysmal (in spells) and whooping, in whooping-cough; dry and hollow, when sympathetic or nervous.

Expectoration is white, thin, and mucous, in catarrh and early bronchitis; yellow and thick {purulent) in severe and protracted bronchitis; rusty, in the middle stage of pneumonia; bloody, thick, and yellow, in developing consumption (phthisis); in heavy, round, small yellowish, lumps, in advanced consumption; putrid (rotten), in gangrene of the lung.

The Breath is hot, during fever; cold, in the collapse of cholera. The odor of the breath is seldom perfectly agreeable except in a healthy child. Bad teeth and imperfect digestion are common causes of unpleasantness in it. It is very heavy at the commencement of a fever; sour, during an attack of indigestion; rotten, in gangrene of the lung.

Hiccough is produced by a spasm of the diaphragm, at the floor of the chest. It may depend upon indigestion, nervous disorder, or great exhaustion. In the last of these, it is generally a decidedly bad symptom.

Snoring (stertorus), respiration results from oppression of the brain; the cause of which may be either apoplexy, fracture of the skull, dead drunkenness, or narcotism by opium. (Of course we do not forget that some persons snore tremendously during their natural and healthy sleep.)