[3] When we are obliged to stop our bleeding, on account of fainting, before we would otherwise do it, we will find it necessary to repeat the venesection sooner than if this did not happen.
Concerning the exact quantity of blood, which ought, in the different varieties of inflammation, to be detracted, I hold it, from the above principle, to be ridiculous to give any direction; because no general rule can be given, by which we may, a priori, determine the quantity. We are to bleed until we procure an abatement of the action; and to stop whenever this abatement ceases to be really progressive[4]. We are to renew the bleeding, whenever the action again increases, and stop, as before, whenever it is abated, remembering, that, after some time, a more sparing detraction will produce a greater effect, than a more copious one would do, in the commencement of the disease. It must also be attended to, that, owing to the weakness induced by the disease, and by the bleedings, we must, toward the end, bleed at longer intervals; for, if we continue to bleed in the same way as formerly, we would either kill the patient, or at least prevent the act of restoration from taking place; because we would thus diminish the power, or vital energy, which was to perform this act. Those, then, who order a certain number of ounces to be taken away, must reason upon probability, and prescribe less efficaciously, than those who direct no determinate quantity, but regulate their practice by the effects. It is equally foolish in those who order bleeding, pro viribus, and are satisfied with this until their next stated visit; because bleeding until fainting takes place, and not repeating it for some time afterwards, may be doing a great deal too little.
[4] We must distinguish, as has been already mentioned, betwixt a real abatement of the inflammatory action, and a mere temporary suspension of action, or syncope.
As there is a proper time for stopping each individual evacuation, so also is there a period at which we ought to stop the general plan of cure by bleeding, or at least to intermit it. And to determine when this period is come, is sometimes a pretty nice point, and one of much importance; because, if we stop too soon, we allow the action still to go on, and, perhaps, to terminate fatally. On the other hand, if we bleed too long, we sink the parts below the state necessary for recovery, and even accelerate the unfavourable termination. When, for instance, from the state of the pulse, and other circumstances, we apprehend the accession of gangrene, bleeding will not abate pain, but will bring on the mortification sooner, and make it spread farther, as will be afterwards mentioned.