Pure fever is rarefied, mild, its attack passes, lasting from four to twelve hours, and does not exceed this period by much, and if it lasts much longer, then the fever is unclean. In most cases it lasts about seven hours. At the same time, the body quickly warms up, and you see that the heat spreads throughout the body, but the limbs are still cold. Further, with a pure fever, if there is no error in treatment, there are no more than seven circuits; sometimes, due to the rarefaction of matter, it ends in one attack, during which there is vomiting or a cleansing weakness. The maturity of matter is manifested in urine on the first, third, fourth or seventh day, and if the fever greatly exceeds seven cycles, then it belongs to the unclean variety, as is the case when the chill lasts a long time. With a pure fever, the intensification of attacks and their anticipation by chills occurs in a certain order, maintaining similar ratios, but with an unclean fever this occurs unevenly and indefinitely. The same is true if the attacks are similar and uniform; other signs of the duration of fever are as already taught. If you see chills at first, as we defined above, and at the end profuse sweating, then do not doubt that the fever is pure.
If a person suffering from pure fever drinks water, a damp vapor spreads through his body, as if he were about to sweat, and sometimes he actually sweats. And with an unclean fever, great heaviness and tension are felt in the head, the chills and attack are prolonged, lasting up to twenty-four or thirty hours, until the time of the attack has passed, and weakening during the period remaining up to forty-eight hours. The degree to which the duration of the attack exceeds twelve hours corresponds to the level of remoteness of the fever from purity.
With an unclean three-day fever, the manifestations of the maturity of the juices are delayed and weight loss and exhaustion are not noticeable in the patient’s appearance. Sometimes the fever does not end with profuse sweating, and sometimes it does not begin with severe chills and the fever is not so strong. The increase in fever occurs unevenly, but on the contrary, it seems to intensify, then the increase is ahead of its time and then the fever decreases. Severe events with it are rare.