(From coagulo, to incrassate or curdle). In general such bodies as coagulate fluids; but in medicine it signifies more particularly such remedies or poisons as coagulate the blood and juices flowing from it.
Though poisons were generally accused of coagulating the fluids, yet various other substances were employed for this purpose; and, at the present moment, spermaceti is sometimes given after lying-in, to prevent the excessive lochial discharge, and occasionally as a check to the haemorrhages from the lungs. In the humoral pathology the class of coagulants are still numerous, and with those who retain the theory of preternatural tenuity or lentor, they must be still cherished as remedies, or dreaded as injurious. We see no instance, however, of coagulation of the vital fluids, but in cases of polypi in the heart or larger arteries; and these concretions are rather owing to occasional stagnations of the circulation from faintings, or similar temporary causes of suspended circulation, than any fault in the fluids. Some effects formerly attributed to coagulation, we now know to be the effect only of adhesive inflammation. Externally, these are undoubtedly coagulants; for whatever favours the concretion of the blood flowing from a wound may be styled such. Of this kind arel int, especially when mixed with flour, spiders' webs, sometimes the white of an egg, or similar applications, which have been styled styptics. Internally we find an effect from one medicine that may be supposed to resemble it, viz. that of gum arabic, which, when used in large quantities, we think has sometimes lessened the flow of urine. Authors, however, who claim some credit, have arranged under this head the consolida, pulmonaria, aloes, gum benjamin, the balsams, spirit of wine, sarcocolla, lapis hybernicus, the leaves of the elm, hypericum, and caprifolium, some of which certainly act as styptics when applied externally.