side affected, simply containing air, or we have it partly occupied by air and partly by a serous and albuminous effusion in variable quantity and proportions. In prosecuting the inspection of the body, we uniformly observe that a quantity of gas, sometimes having an offensive smell, rushes out as soon as the knife has penetrated the chest; and on examining the interior, the lung, unless prevented by partial adhesions, is found compressed into a small space against the spine and mediastinum. When the cavity contains air alone, the pleura may be merely drier than natural; more frequently, however, it is covered with some form of albuminous deposit, and especially so when there also exists more or less fluid effusion.

In every case of pneumothorax there is more or less dyspnoea. This dyspnoea may come on suddenly, and is then occasionally of extreme urgency, especially if, as often happens, there previously existed phthisical or other serious disease of the lungs. There may also be protrusion of the ribs, and even displacement of parts, according to the quantity of air, or of air and fluid effused; the other physical signs necessarily varying with the immediate cause of the disorder. When air alone is effused, we have impaired mobility of the ribs, preternatural resonance on percussion, and total cessation of all respiratory murmur, except in a small space between the scapula. If fluid be mixed with the air, then, in consequence of the fluid gravitating, whilst the air ascends, we have preternatural resonance above, dullness of sound below, and occasionally metallic tinkling; whereas if a decided communication exist between the pleural cavity and bronchi, we detect both metallic tinkling and the amphoric sound.

The pathognomonic sign of pneumothorax is a combination of clearness of sound on percussion with complete

obliteration of respiratory murmur everywhere, except in a small space between the scapula. This peculiarity is quite sufficient to distinguish the disease in every instance. In vesicular emphysema, the clearness of sound is attended with merely a diminution of the respiratory murmur. The metallic tinkling and amphoric sound may accompany any such disorganization of the lung as causes the formation of a vast cavity communicating with the bronchi, and consequently containing a mixture of air and fluid; but such cases are not very common, and the history and accompanying symptoms will at once declare the true nature of the disorder. It must not be supposed that disease exists in the sound side because it happens to be less resonant than the other, an error, however, which auscultation will instantly correct; neither must it be forgotten, in examining the left side, that fluid and flatus in the stomach may give rise to great resonance on percussion, and metallic tinkling.

The treatment of pneumothorax will depend entirely upon the nature of the disease with which it happens to be associated. Cases of pneumo-thorax, independent of organic or other serious disease of the lungs or pleura, are extremely rare; and if they do occur, they will probably be attended with little danger, the air being gradually removed by absorption without much assistance from art. If in any case of pneumothorax the oppression of the breathing become alarming, it may be prudent or even necessary to perform the operation of paracentesis thoracis.

PLEURITIS, OR PLEURISY.

In order to acquire a correct knowledge of this disease, it is necessary to bear in mind that it consists in inflammation of a serous membrane; that although this inflammation may probably diminish or suspend the secretion of the membrane in the first instance, it in a very short time leads to an effusion of serum and solid albumen; that the quantity and relative proportion of these two products are much influenced by the intensity of the inflammation, but especially by the age and constitution of the patient; that in young persons of good constitution, acute inflammation usually causes an effusion of a much larger proportion of solid albumen than when it occurs in scrofulous habits and in old and cachectic constitutions; that in the former the solid albumen takes on organization, and the serum is absorbed with comparative rapidity; that in the latter the serum is for the most part considerable in quantity, whilst the solid albumen is scanty, little capable of organization, and manifests a strong tendency to take on a flaky, granular, or puriform character.

Acute pleurisy is commonly indicated by a severe pungent pain in some part of the chest, dyspnoea, and cough; these symptoms being, in most instances, preceded by chilliness, rigors, or shivering, and a feeling of general indisposition; and accompanied or presently followed by heat of skin, thirst, a white tongue, and a frequent, full, and often hard pulse.

Of all the symptoms, the acute pungent pain is that which is most uniformly present; it may of course exist in any part of the chest, according to the seat of the inflammation; it for the most part gradually, but sometimes rapidly, increases in severity, and is occasionally observed

to shoot or radiate in various directions. It differs much in degree in different cases, being in general most severe in persons of vigorous constitution and of a tense or rigid fibre; whereas in old, relaxed, and leucophlegmatic subjects, it may be comparatively slight or even altogether absent. It is greatly increased by drawing in a deep inspiration, by the act of coughing, and not unfrequently, though not uniformly, by pressure made upon the intercostal spaces situated over the inflamed part. Its intensity is also very much influenced by the seat of the inflammation, and occasionally by the position of the patient. It is most severe when inflammation attacks the inferior and lateral, or the inferior and anterior parts of the chest, where the diaphragm is attached to the ribs; but is occasionally very inconsiderable when the upper part of the chest is affected. As regards the effect of position, may be stated generally, that whatever position causes the most considerable elevation of the ribs, covered by the inflamed membrane, will occasion the greatest pain: and hence it is, that in pleurisy situated at the upper part of the chest, the patient will often lie indifferently on either side or upon his back; whilst if situated very low down, he will, in order to preserve the ribs in a state of repose, often prefer lying on the side affected, or even endeavour by pressure to prevent that movement of the ribs, which he soon discovers to be the chief cause of his suffering. The duration of the pain will necessarily vary with the promptitude and activity of the treatment. If proper remedies be early employed it will seldom last longer than two, three, or four days; and even when the case is neg lected it will now and then subside and almost disappear in less than a week.

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The dyspnoea varies in degree, according to the seve

rity and seat of the inflammation; it varies in kind with the period of the disease. In the early stage of a severe attack, the dyspnoea is manifestly occasioned by the inability of the patient to expand his chest without aggravating the pain; whilst at a later period it arises chiefly or entirely from compression of the lung by serous and albuminous effusion. If at an early period the patient be desired to inspire deeply, he will, on making the attempt, suddenly come to a stop or check, attended with a sort of catch or sob, owing to the pungency of the pain, or stitch, produced by the effort. So long, therefore, as the pain continues thus severe, the respiration is short and hurried. We also find, as might be expected, that the dyspnoea at an early period is most considerable when the inflammation is so situated as to produce the greatest degree of pain; it is least considerable when inflammation is situated at the upper part of the chest; it is generally more severe the lower it extends; it is not observed to give rise to any very unusual distress when it attacks the base of the lungs and that portion of the diaphragm on which the base of the lung rests; but when it attacks the inferior and anterior or inferior and lateral regions where the diaphragm is attached to the ribs, the dyspnoea and pain often become excruciating, almost throw the patient into convulsions, and give rise to that distortion and expression of agony in the countenance, usually described as the Risus Sardonicus, or Sardonic Grin.

At a later period of the disease, the dyspnoea arises chiefly or entirely from serous and albuminous effusion compressing the lung; it is then often unattended by the least pain; it is of course more or less urgent, according to the quantity of the effusion; and indeed when very abundant, the patient, on attempting to lie on the sound side,