Chronic lead-poisoning is characterized by anemia, intestinal colic, constipation, a blue line on the gums (deposit of lead sulphide), and paralysis of the forearms (wrist-drop).
Magnesium Sulphate (Epsom Salt).—This salt is an excellent hydragogue cathartic, producing in the course of a few hours copious watery stools. It is also employed as an antidote in acute lead-poisoning and carbolic-acid poisoning.
To secure the most prompt and powerful cathartic effect the drug is best given before breakfast, in a single dose, and with but a small quantity of water. Dose, from 1 to 8 drams (4-31 gm.).
Magnesium Oxid (Magnesia).—This is a white, tasteless, and insoluble powder. It is a cathartic, but much milder in action than Epsom salt. Dose, from 10 to 60 grains (0.6-4 gm.).
Magnesium Citrate.—An effervescing solution of this drug is much used as an agreeable laxative. The dose is from 6 to 12 ounces (180-360 c.c.).
Mercury.—The most important preparations of this metal are calomel, blue mass, corrosive sublimate, oxid of mercury, iodid of mercury, nitrate of mercury, and ointment of mercury.
Calomel (Hydrargyri Chloridi Mite).—This preparation is employed internally as a cathartic and gastric sedative, and externally as a stimulating and antiseptic dusting-powder. As a cathartic its best effect is secured by giving it in doses of from ⅒ to ⅙ grain (0.006-0.01 gm.) every half-hour or hour, until a grain has been taken. In this way the whole amount ingested is absorbed. When large doses are employed much of the drug escapes absorption.
Blue Mass or Blue Pill (Massa Hydrargyri).—This is a mixture of mercury, glycerin, honey, and licorice. Its action is much like that of calomel.
Corrosive Sublimate or Bichlorid of Mercury (Hydrargyri Chloridum Corrosivum).—Although irritant, toxic, and destructive to instruments, no other drug has supplanted this salt as an antiseptic for use in general surgery. The following are the strengths of the solutions usually employed for various purposes: for the skin, 1 : 1000 to 1 : 500; for wounds, 1 : 10,000 to 1 : 2000; for cavities of the body, 1 : 20,000 to 1 : 5000. Corrosive sublimate is not a good disinfectant for stools, sputa, etc., as it forms an impenetrable coagulum on the outside of the mass. Internally, corrosive sublimate is used as an alterative in constitutional diseases in doses of ¹/₆₀ to ¹/₁₂ of a grain (0.001-0.005 gm.).
Oxid of Mercury.—This appears in two forms—yellow oxid and red oxid. Both preparations are employed externally in the form of ointments for their alterative properties.