On the 2d of _March_, a Soldier, of the Fifty-first Regiment of Foot, was brought to the Hospital, with a violent Pain in the left Side, and a great Difficulty of Breathing. Upon examining him, he told me, that about two Years before he had had a violent Stitch in his left Side, towards the lower Part of the Thorax; that ever since he had been subject to a Difficulty of Breathing; and at Times to a Pain in the Side; but that he had only been seized with the violent Pain and Difficulty of Breathing he then complained of, about five Days before, occasioned by catching Cold, on being billeted in a low, cold, and damp House.--His Pulse was quick, the Pain of his Side and Difficulty of Breathing so great, that he could not sleep, nor lie down, but was obliged to sit constantly in an erect Posture; his Tongue was white and furred, and he had had no Stools for three Days: He was ordered to be blooded immediately; and to take a Dose of Salts; and his Side to be rubbed with the _linimentum volatile_. 3d. His Breathing and Pain of the Side were easier; he had slept a little in the Night, and could lie on his right side, but not on his left. He was ordered the Squill Mixture. 4th. His Breathing was worse; he was blooded a second Time; had a large Blister applied to his Side, and was ordered to continue the Use of the Squill Mixture. On the 5th, 6th, and 7th, he seemed easier, though the Breathing was still much affected, and his Pulse quick and low, attended with a hectic Heat. On the 8th, he told me that his left Side was swelled: On examining, I observed a Fullness in that Side of the Thorax; and on pressing with my Fingers between the Ribs, I thought I felt an obscure Fluctuation of a deep-seated Fluid. From these Appearances, and the History of the Case, I judged that there was a Collection of some Fluid within the Cavity of the Chest; and that the only Means left to give Relief, was to make an Opening into the Cavity, and so evacuate the Fluid. I therefore proposed to him the Operation of the Empyema, to be performed immediately; which he several Times obstinately refused to submit to: He allowed a Seton to be put in his Side, but that did not answer the End proposed: He languished six Days longer; and died the 14th of _March_. Next Day an Opening was made in the Thorax, in the Part where the Operation was proposed to have been performed; as soon as the Pleura was cut through, some Quarts of Water rushed out. We then opened the Thorax, and found still some Water in the left Cavity. The Pericardium was thickened, and slightly inflamed, and adhered to the Diaphragm; which was likewise a little thickened and inflamed in the adhering Part; the Lungs on that Side were much compressed, and contracted by the Pressure of the Water; but on being inflated and cut, seemed in a sound State, except that they were slightly inflamed. The Lungs of the left Side adhered every-where firmly to the Thorax, but seemed