XIII. In drawing blood, the quantity should be large or small at a time, according to the state of the system. In cases where the pulse acts with force and freedom, from 10 to 20 ounces of blood may be taken at once; but in cases where the pulse is much depressed, it will be better to take away but a few ounces at a time, and to repeat it three or four times a day. By this means the blood-vessels more _gradually_ recover their vigour, and the apparent bad effects of bleeding are thereby prevented. Perhaps the same advantages might be derived, in many other cases, from the gradual abstraction of stimuli, that are derived from the gradual increase of their force and number, in their application to the body. For a number of facts in support of this practice, the reader is referred to the history of the yellow fever, in the year 1793. In an inflammatory fever, the character of which is not accurately known, it is safest to begin with moderate bleeding, and to increase it in quantity, according as the violence and duration of the disease shall make it necessary. In fevers, and other diseases, which run their courses in a few days or hours, and which threaten immediate dissolution, there can be no limits fixed to the quantity of blood which may be drawn at once, or in a short time. Botallus drew three, four, and five pints in a day, in such cases. Dr. Jackson drew fifty-six ounces of blood, at one time, from a Mr. Thompson, of the British hospitals, in a fever of great violence and danger. This patient was instantly relieved from what he styled "chains and horrors." In three or four hours he was out of danger, and in four days, the doctor adds, returned to his duty[60]. Dr. Physick drew ninety ounces, by weight, from Dr. Dewees, in a sudden attack of the apoplectic state of fever, at one bleeding, and thereby restored him so speedily to health, that he was able to attend to his business in three days afterwards. In chronic states of fever, of an inflammatory type, small and frequent bleedings, are to be preferred to large ones. We use mercury, antimony, and diet drinks as alteratives in many diseases with advantage. We do not expect to remove debility by two or three immersions in a cold bath. We persist with patience in prescribing all the above remedies for months and years, before we expect to reap the full benefits of them. Why should not blood-letting be used in the same way, and have the same chance of doing good? I have long ago adopted this _alterative_ mode of using it, and I can now look around me, and with pleasure behold a number of persons of both sexes who owe their lives to it. In many cases I have prescribed it once in two or three months, for several years, and in some I have advised it every two weeks, for several months. [60] Remarks on the Constitution of the Medical Department of the British Army.