blood in the part at the instant of death, its putrefaction is less sudden; it first putrifies, then blackens, and allows but little sanies to escape; this is the dry gangrene. Thus in a dead body, if one part is much loaded with blood, as the head of those that have died of apoplexy, its putrefaction is much more rapid and moist than that of the parts in which this fluid is less abundant. In the gangrene which succeeds mortification produced by cold, there is often dryness of the part, because there was but little blood in it at death. How little many physicians know of the progress of nature in the employment of antiseptics, which they apply in the living economy, as upon flesh without life. Antiseptics are applied for one of two purposes, either to prevent the death of the part, or its putrefaction. 1st. If it is with the first intention, antiseptics should be varied. By untying the artery of a limb of an animal that has been tied, you will perform an antiseptic operation. Bleeding and emollient applications which lessen the violence of inflammation in a phlegmon, are antiseptics. A tonic as wine and all stimulants which excite the vital forces in a part in which they are languid after a bruise, are antiseptics. This word is then extremely improper when it is applied to medicines designed to prevent the mortification of the parts. Antiseptics are employed to prevent a dead part in the midst of living ones becoming putrid; some effect is obtained; thus by sprinkling cinchona, muriate of soda, or any neutral salt, by moistening a limb, a portion of skin, the extremity of the nose, &c. which is dead from any cause, the putrefaction will be arrested, as in a dead body upon which the same means are employed. But what will be the result of it? a little less fetor in the surrounding parts and less danger of their receiving the influence of the emanations of the dead part; but it is always necessary that this should come off; antiseptics will never bring it to life. Hence it is evident that these means should be considered in two points of view entirely different. The first prevent mortification, and vary remarkably though they are designed to effect the same object; thus our means of curing retention of urine are very variable, oftentimes opposite, according to the cause which tends to produce this retention. The others prevent putrefaction, without restoring the parts to life; now these are uniformly the same, whatever may have been the cause of the local death. _Action of the Air._