Mercury (Hg = 198.5) is a metal obtained by roasting the native sulphids. Mined in the Americas, Spain, Japan, and Australia.

Pharmacodynamics.

Central Nervous System. - Higher centers are involved obscurely in chronic poisoning, the reflex excitability of the cord being also heightened. Peripheral neuritis often appears, though late.

Muscular system is not affected directly.

Respiratory system shows no direct effects.

Heart seems not affected except in acute poisoning from overwhelming doses, when heart is weakened by direct action.

Blood-pressure falls, in overwhelming doses, as a result of peripheral dilatation; probably a local action.

Alimentary Tract. - Mercury markedly irritates the mucosa of the (stomach) caecum and colon. Does not directly increase the bile flow.

Secretory Glands. - Secretory apparatus of parotids greatly stimulated.

Kidney. - Marked irritation of secreting epithelium of tubules.

Metabolism. - Mercury lessens the alkalinity of the blood, and is thought to stimulate nutrition and leucocytosis.

Temperature. - No direct effect.

Absorption takes place readily, probably as an albuminate.

Excretion takes place by all the emunctories, but chiefly by the intestines and kidneys. It begins within an hour after the drug" is taken, but continues very slowly.

Local Action. - Irritant, becoming escharotic.

Symptoms.

Medicinal Dose. Stool in 8 to 10 hours. Slight mental depression. Some symptoms of acute poisoning in some patients. Acute Poisoning. Burning pain in stomach. (Salivation). Nausea and vomiting. Diarrhea; bloody stools. Violent tenesmus. Thready, irregular pulse. Shallow, rapid respiration. Cold, clammy perspiration. Pinched features, sunken eyes. Anuria, usually.

Collapse.

Early death from shock, or in several days from exhaustion.

Chronic Poisoning. Metallic taste, fetid breath. Swollen, thickly-coated tongue. Soft, swollen, bluish gums. Salivation and stomatitis. Loosening of teeth, and caries of jaw may ensue. Anorexia, gastritis. Lassitude, diarrhea and colic. Small, weak pulse. Anaemic cachexia. Depression of nervous system.

Therapeutics.

Mercury is very often specific in the second stage of syphilis. Calomel, in-small doses, is valuable in putrefactive diarrhea. Mercurial ointment is used in some chronic skin troubles.

Dosage.

Hydrargyri Chloridum Corrosivum, 0.002 to 0.004 Gm. Hydrargyri Chloridum Mite, 0.008 to 0.03 Gm.