CHAP. VI. OF PNEUMONIA, OR PNEUMONIC INFLAMMATION. 334. UNDER this title I mean to comprehend the whole of the inflammations affecting either the viscera of the thorax, or the membrane lining the interior surface of that cavity: for neither do our diagnostics serve to ascertain exactly the seat of the disease; nor does the difference in the seat of the disease, exhibit any considerable variation in the state of the symptoms, nor lead to any differ ence in the method of cure. 335. Pneumonic inflammation, however various in its seat, seems to me to be always known and distinguished by the following symptoms: pyrexia, difficult breathing, cough, and pain in some part of the thorax. But these symptoms are, on dif ferent occasions, variously modified. 336. The disease almost always comes on with a cold stage, and is accompanied with the other symptoms of pyrexia; though, in a few instances, the pulse may not be more frequent, nor the heat of the body increased beyond what is natural. Sometimes the pyrexia is from the beginning ac companied with the other symptoms; but fre quently it is formed for some hours before the other symptoms become considerable, and particularly before the pain be felt. For the most part, the pulse is frequent, full, strong, hard, and quick; but, in a few instances, especially in the advanced state of the disease, the pulse is weak and soft, and at the same time irregular. 337. The difficulty of breathing is always present, and most considerable in inspiration; both because the lungs do not easily admit of a full dilatation, and because the dilatation aggravates the pain attending the disease. The difficulty of breathing is also greater when the patient is in one posture of his body rather than another. It is generally greater when he lies upon the side affected; but sometimes the contrary happens. Very often the patient cannot lie easy upon either side, finding ease only when lying on his back; and sometimes he cannot breathe easily, except when in somewhat of an erect posture. 338. A cough always attends this disease; but, in different cases, is more or less urgent and painful. It is sometimes dry, that is, without any expectoration, especially in the beginning of the disease; but more commonly it is, even from the first, moist, and the matter spit up various, both in consistence and colour, and frequently it is streaked with blood. 339. The pain attending this disease is, in different cases, felt in different parts of the thorax, but most frequently in one side. It has been said to affect the right side more frequently than the left; but this is not certain; while, on the other hand, it is certain that the left side has been very often affected. The pain is felt sometimes as if it were under the sternum; sometimes in the back between the shoulders, and, when in the sides, its place has been higher or lower, more forward or backward: but the place of all others most frequently affected is about the sixth or seventh rib, near the middle of its length, or a little more forward. The pain is often severe and pungent; but sometimes more dull and obtuse, with a sense of weight rather than of pain. It is most especially severe and pungent when occupying the place last mentioned. For the most part, it continues fixed in one place; but sometimes shoots from the side to the scapula on one hand, or to the sternum and clavicle on the other. 340. The varying state of symptoms now mentioned does not always ascertain precisely the seat of the disease. To me it seems probable, that the disease is always seated, or at least begins, in some part of the pleura; taking that membrane in its greatest extent, as now commonly understood; that is, as covering not only the internal surface of the cavity of the thorax, but also as forming the mediastinum, and as extended over the pericardium, and over the whole surface of the lungs. 341. There is, therefore, little foundation for distinguishing this disease by different appellations taken from the part which may be supposed to be chiefly affected. The term pleurisy, might with propriety be applied to every case of the disease; and has been very improperly limited to that inflammation which begins in, and chiefly affects, the pleura costalis. I have no doubt that such a case does truly occur but, at the same time, I appre hend it to be a rare occurrence; and that the dis ease much more frequently begins in, and chiefly affects, the pleura investing the lungs, producing all the symptoms supposed to belong to what has been called the Pleuritis vera. 342. Some physicians have imagined, that there a case of pneumonic inflammation particularly entitled to the appellation of Peripneumoný; and that is, the case of an inflammation beginning in the parenchyma, or cellular texture of the lungs, and having its seat chiefly there. But it seems to me very doubtful, if any acute inflammation of the lungs, or any disease which has been called peripneumony, be of that kind. It seems probable; that every acute inflammation begins in membra nous parts; and, in every dissection of persons dead of peripneumony, the external membrane of the lungs, or some part of the pleura, has appeared to have been considerably affected. 343. An inflammation of the pleura covering the upper surface of the diaphragm, has been distinguished by the appellation of Paraphrenitis, as supposed to be attended with the peculiar symp toms of delirium, risus sardonicus, and other convulsive motions: but it is certain, that an inflammation of that portion of the pleura, and affecting also even the muscular substance of the diaphragm, has often taken place without of these symptoms; and I have not met with either dissections, or any accounts of dissections, which support the opinion, that an inflammation of the pleura covering the diaphragm is attended with delirium more commonly than any other pneumonic inflammation. any 344. With respect to the seat of pneumonic inflammation, I must observe further, that, al though it may arise and subsist chiefly in one part of the pleura only, it is however frequently communicated to other parts of the same, and commonly communicates a morbid affection through its whole extent. 345. The remote cause of pneumonic inflam |