which, from the greater heat of the atmosphere, and the more heterogeneous nature of the putrid matters which stagnate in our ponds and gutters, the exhalation probably possesses a more active and stimulating quality. Thus the mild remittents in June, and in the beginning of July, which were produced by the usual filth of the streets of Philadelphia, in the year 1793, differed very much from the malignant remitting yellow fever which was produced by the stench of the putrid coffee a few weeks afterwards. Sir John Pringle long ago taught the inefficacy of bark in certain bilious fevers. But Dr. Chisholm has done great service to medicine by recording its ill effects in the Beullam fever. "Head-ach (says the doctor), a heavy dull eye, with a considerable protrusion from its orbits, low spirits, thirst, and a total want of appetite, were the general consequences of the treatment with bark without the previous antiphlogistic." I have mentioned a case of internal dropsy of the brain having been produced by the improper use of the bark, in a son of Mr. Coates. I have no doubt but this disease, as also palsy and consumption, obstructions of the liver and bowels, and dropsies of the belly and limbs, are often induced by the use of the bark, during an inflammatory state of the blood-vessels. It is to be lamented that the association of certain diseases and remedies, in the minds of physicians, becomes so fixed, as to refuse to yield to the influence of reason. Thus pain and opium, dropsy and foxglove, low spirits and assaf[oe]tida, and, above all, an intermitting fever and bark, are all connected together, in common practice, as mechanically as the candle and the snuffers are in the mind of an old and steady house servant. To abolish the mischief of these mechanical associations in medicine, it will be necessary for physicians to prescribe only for the different states of the system. Finding the bark to be so universally ineffectual or hurtful, I substituted Columbo root, the Carribean bark, and several other bitters, in its place, but without success. They did less harm than the jesuit's bark, but they did not check the return of a single paroxysm of fever. I know that bark was given in this fever in some instances in which the patients recovered; but they were subject, during the winter, and in the following spring, to frequent relapses, and, in some instances, to affections of the brain and lungs. In the highest grade of the fever it certainly accelerated a supposed putrefaction of the blood, and precipitated death. The practice of physicians who create this gangrenous state of fever by means of the bark, resembles the conduct of a horse, who attempts by pawing to remove his shadow in a stream of water, and thereby renders it so turbid that he is unable to drink it.