Copper (cuprum) and its salts have a peculiarly deleterious action upon the lower forms of plant life, a mere trace in water, as from dragging bags of copper sulphate through the water, being found sufficient to keep it free from algal growth without injuring the higher plant life or the animal life. Even contaminated water left in a copper vessel will after a time be found aseptic. But Clark and Gage warn against the assumption that the water will be freed from bacteria in any reasonable length of time, and they find that vessels made of other metals will be just as effective as copper. Pennington and associates claim that 1 part of copper sulphate in 2,000,000 will kill typhoid bacilli in ten hours; but Clark and Gage find that even 1 in 100,000 kills them only occasionally, and that copper sulphate, to be safe, must be present in as much as 1 part in 1000.

The salt regularly employed in medicine is the sulphate, or blue-stone. It is locally astringent, irritating, and even caustic. Its taste is harsh and strongly metallic, and when it is swallowed it irritates the stomach and causes vomiting.

Uses

Sticks made of copper sulphate are used as an astringent and caustic for exuberant granulations and granulated eyelids. A solution of 5 to 15 grains in an ounce is used locally in conjunctivitis, urethritis, and vaginitis. Ten grains (0.7 gm.) in solution have been used as an emetic, but if it is not promptly vomited it may injure the stomach. It is recommended in dose of 1/4 to 1 grain (0.015-0.06 gm.) in actinomycosis and sporotrichosis. Claims made for copper salts as remedies for tuberculosis have not been substantiated.

Toxicology

Acute poisoning is that of an irritant, and is usually checked by the prompt vomiting of the drug. Chronic poisoning occurs especially in brass workers, the symptoms resembling those of poisoning by other metals. Even the minute amounts used to color canned vegetables may be deleterious.