Internally. - Digestive System. - The action of the soluble and insoluble salts is distinct. The line between physiological action and toxic action is difficult to draw. The soluble salts are, even in minute doses, somewhat astringent or even corrosive. In larger doses they are powerfully escharotic. The action of soluble salts of mercury is to slightly inhibit the digestive processes. The insoluble salts are slightly irritating and cause increased peristalsis, and increased secretions. They have little action on the digestive ferments.

Circulatory System. - Mercury in small doses has little action on the heart or vessels. The blood-making organs are stimulated by small doses, resulting in an increase of hemoglobin and of red cells. In lower animals a pseudo-antitoxic power has been demonstrated. Physiological stimulation soon passes over into toxic action with cachexia, leucocytosis, and other poisonous symptoms (q. v.).

Nervous System. - Tonic doses have little effect. There may be some erethism, muscular tremor, and slight peripheral signs preceding the development of more distinct toxic effects.

Respiratory System. - Small doses are not known to affect the respiratory action.

Excretion and Secretion. - The kidney epithelium is somewhat irritated by mercury. Diuresis is common.

The absorption of mercury is gradual; yet, notwithstanding the fact that every secretion of the body contributes to its general expulsion from the system, its cumulative action is a well-established fact.

Elimination occurs chiefly by the urine, the saliva, bile, sweat, milk, and feces. Even the semen shares in the process. Single doses may be eliminated in twenty-four hours, but the drug has been detected in the liver a year after the discontinuance of prolonged treatment. Mercury has been found in serum and in pus from ulcers. After death the kidneys and liver contain the largest amounts of the metal.

Untoward Action. - Many affections of the skin manifest themselves after the exhibition of mercury, erythema and eczema (eczema mercuriale) frequently occurring after either the ingestion or the external application of mercurial preparations.

In certain persons having an idiosyncrasy regarding this drug, extreme salivation and stomatitis may be induced by the internal use or the external application of mercurial preparations in medicinal quantities.

Medicinal doses may produce, in susceptible persons, marked disturbances of nutrition, sensation, and motion to such a degree as to suggest poisoning.

Poisoning. - Although mercury in a metallic state is comparatively innocuous, its vapor is capable of producing violent and dangerous symptoms. All the salts are active poisons, especially that known as corrosive sublimate. There are great variations in the grades of poisoning by mercury, and careful attention to its idiosyncrasies should not be overlooked. Poisoning may be divided into the acute and chronic varieties.

Acute Poisoning. - This is not as common a form of poisoning at present as in former days, because of the intensely acrid character of the mercury salts. There is usually a burning, metallic taste, whitish precipitate on the gums, with nausea and vomiting. Shreds of bloody stomach mucosa are frequently stripped off. Intense colicky pains are developed with diarrhea, which is often bloody or watery, and with much tenesmus; symptoms of collapse, such as cyanosis, cold skin, small, rapid pulse (150 or over), irregular rapid respiration. Sometimes giddiness, sometimes unconsciousness, may develop. Frequently there is anuria, or bloody and albumin-filled urine. Death occurs usually from shock, and has resulted from 1/8 grain of corrosive sublimate in one to two hours. Occasionally death takes place after several days with the development of the symptoms of chronic poisoning. A form of rapid poisoning occurs from the inhalation of mercury containing vapors, as in mirror factories. Workers on hat feltings often suffer.

Chronic Poisoning. - This may result from a single dose, but more often from prolonged small dosage, from the breathing of vapors containing mercury. The prodromal symptoms occur in the mouth. They are metallic taste, soreness of teeth, fetid breath, spongy, inflamed gums, and salivation. Discontinuance of the mercury and mouth hygiene usually clears up these symptoms. If, however, dosage is continued or rules of cleanliness neglected, the tongue may become swollen; there is extreme salivation with marked fetor; ulceration and bleeding may take place, and the mouth gets in an abominable condition, with loose teeth or even jaw necrosis. Other concomitant symptoms may develop, such as anorexia, nausea, colic, diarrhea, constipation, sometimes a distinct febrile movement of the temperature (secondary infections). Emaciation, cachexia, motor weakness, restlessness, may come on. There is frequently a fine muscular tremor, and later paresthesiae, anesthesiae, and paralysis may develop. Skin eruptions are not infrequent.

Treatment of Poisoning. - In acute poisoning from corrosive sublimate or other active salt of mercury it is necessary to evacuate the stomach as quickly as possible and give white of eggs freely. The after-treatment is similar to that of other corrosive poisons -the use of demulcents and opiates.

For salivation, potassium chlorate probably occupies the first place as a prophylactic and curative agent. It is employed as a gargle and mouth-wash, in a 2 to 3 per cent. solution. An astringent wash is frequently necessary. Such drugs as tannin, myrrh, krameria, etc., may be used for this purpose. Where there is extensive ulceration of the mouth, disinfectant and antiseptic solutions will be found desirable.

In cases of chronic mercurial poisoning it is of primary importance to remove all traces of the drug from the body by means of iodides, the dosage being limited in quantity, but continued for some time. A change of air, liberal and nutritious diet, and tonics are also necessary.