In all of them the bark had been given at some period or other; and the flowers of zinc were now tried in all, except the last. In three out of the five this medicine had the most visible good effects. In one the disease was so speedily removed, that there was only one fit after the first day of taking this medicine, and the other two had recovered perfectly after it had been used for seven days. In these cases there can be little or no ambiguity with regard to the real efficacy of the medicine, as the disease had lasted from two to six months, and there was no other circumstance of change in the situation or treatment of the patients that could account for their recovery. Of the two cases in which it failed, one was the tertian of three months, attended with the eruption; the other was the relapsed tertian of three days. With regard to the dose, I began with giving it in the quantity of two grains thrice a day, which, in some, produced the desired effect, and without the least sensible operation on the stomach or bowels. If this dose did not stop the fits after a few days trial, it was increased to three grains, which, in some, would produce a little sickness. I found that four grains ruffled the stomach a good deal; but if the patient is gradually habituated to it, even more than this may be given without inconvenience. In those cases in which it was successful it was not found necessary to give more than two grains at a dose, except in one of them, in which three were given the day before the fit ceased. In the two unsuccessful cases the medicine had a fair trial for a fortnight; but one of them getting no better, and the other seeming to get worse, it was left off. The cases to which this medicine is adapted are those that have extremely distinct remissions, with no symptoms of bile nor any local affection. When agues come to be long protracted, they are frequently what may be called nervous; that is, consisting of certain morbid motions that seem to be induced by habit, after the original cause is removed, and with a tolerable enjoyment of appetite, sleep, and all the functions of life, during the intermission. The two cases in which the zinc failed recovered by the use of the bark. This had been unsuccessfully tried before, and its good effects now might either depend on its having been left off for some time, whereby the body recovered its sensibility to its virtues, or it might be in consequence of administering it in ardent spirits with a few grains of capsicum and ginger, additions which I found to improve its effects in other cases, and is a mode of giving it well suited to this climate. The zinc was not tried in the sixth case, on account of the local affection and the remission being short and imperfect.