Industrial mercurial poisoning often begins with inflammation of the mucous membrane of the mouth and gums. There is increased flow of saliva, a disagreeable metallic taste in the mouth, and foul breath. This may be limited to a simple inflammation of the gum, or go on to ulceration with falling out of teeth, or even to gangrene of the gum and mucous membrane inside the mouth. Gastric attacks also occur in the early stages; occasionally, however, they are absent. The main symptoms of chronic mercurial poisoning are nervous and psychical derangement, to which in severe cases are added general disturbance of digestion and loss of strength. Sometimes, after repeated attacks, more or less severe, a cachectic condition is induced, showing itself in general emaciation, decrease of strength, atrophy of the muscles, anæmia, and disturbed digestion, which—often intensified by some intercurrent disease, such as tuberculosis—lead to death. Slight cases of mercurialism recover, leaving no evil results, if the patient is removed in time from the influence of the poison. The treatment of chronic mercury poisoning is symptomatic. To allay the inflammation of the mucous membrane of the mouth the patient should use a mouth wash of potassium chlorate and peroxide of hydrogen; the general condition should be raised by strengthening, unstimulating food; for the nervous symptoms baths and electricity should be tried; and for very marked erythism and tremor recourse to narcotics may be necessary. Industrial mercurial poisoning is produced not only by metallic mercury but also by many compounds, of which industrially the oxides are the most important. Nitrate of mercury (Hg₂(NO₃)₂) comes into account in the treatment of fur. Mercury cyanide (HgCy₂) deserves mention, as small quantities cause mercurial and large quantities cyanogen poisoning. MANGANESE, MANGANESE COMPOUNDS Manganese (Mn) or manganese compounds are used industrially in fine powder; continuous absorption of dust containing manganese produces chronic manganese poisoning. Instances of such poisoning are not very numerous; altogether about twenty cases have been described. Recent publications agree in asserting that only the dust rich in manganese protoxide is dangerous.