=Yellow Fever.=--The yellow fever is one of the varied forms of the typhus, the name being derived front the hue of the victim, while the Spanish call it _vomito negro_--the black vomit--from one of its symptoms. Its home is tropical Africa and tropical America, but it is never found in India and China, hot as the climate may be. The cause of this difference, however, has never been explained. Its greatest prevalence is on the sea-coast or banks of navigable rivers. Its ordinary duration of attack is from 36 to 48 hours. The yellow tinge first appears in the eye and then spreads over the face, gradually reaching the extremities and often becoming dark brown. The rate of mortality varies in a striking degree, for in some places one-third of the cases prove fatal, while in others the mortality reaches two-thirds, and then at other times it has not exceeded three per cent. Treatment varies more in this disease than in any other, which is a proof that thus far it has baffled the best practitioners. Like all other forms of pestilence, it not only walketh in darkness but destroyeth at noonday. The disease itself is not as dangerous as typhoid fever when properly handled. It is a continuous fever, lasting 72 hours. The premonitory symptoms are a pain in the back of the head and in the loins, followed by a slight chill. The pulse and temperature then rise rapidly, the former attaining usually about 110 beats to the minute, and the latter 104 degrees in a few hours. On the second day the pulse begins to drop and continues to do so slowly until the normal is reached, while the temperature remains steady, and this peculiarity is the one pathognomonic symptom of the disease, as ascertained by experts who have studied many epidemics. Toward the third day the temperature is often up to 105. This is a grave symptom, and unless it can speedily be reduced, "black vomit" or gastric hemorrhage appears, or the kidneys refuse to act on account of acute inflammation and destruction of tissue. The famous black vomit is not fatal in more than 50 per cent of cases well treated, but when albumen appears in the urine death almost inevitably follows. Nursing is everything. The treatment of the disease is wholly expectant. A hot mustard foot-bath and a large dose of castor-oil are preliminaries. After this nothing is given but orange-leaf tea, to promote perspiration, and sometimes a little extract of jaborandi. Champagne in small quantities is found to be the best preventive of black vomit, and dry cupping and blisters are resorted to in case of a tendency to kidney trouble. The nurse does more than the doctor in yellow fever to effect a cure, and in New Orleans nearly all the black "mammies" are experts in handling the disease, which undoubtedly accounts for the very low mortality in that city's epidemics. To watch the patient, be quick to start a fire if a north wind comes to chill the air, to keep the clothing adjusted, see that no talking is allowed, and