To trace the history of copper compounds it would be necessary to go back much further than the fourth millennium BC. Records found in the tombs of the early Egyptians suggest that, at least, this ancient civilisation employed copper sulphate as a mordant in their dyeing process. Today, more than 5,000 years later, copper sulphate is still employed by the world's dyeing industry in the after treatment of certain dyes to improve their fastness to light and washing.
Another equally early recorded use for copper compounds was for the making of ointments and other medical preparations. Later, the Greek civilisation of the pre-Christian era of Hypocrates (circa 400 BC) saw the prescribing of copper sulphate for pulmonary diseases and by the 18th century AD it had come into wide clinical use in the western world, being employed for the treatment of mental disorders and afflictions of the lungs.
It is noteworthy that copper sulphate has lost none of its effectiveness over the centuries, neither have any harmful side effects been reported. Copper sulphate is still, however, highly prized by some inhabitants of Africa and Asia for healing sores and skin diseases. In the West it is widely used in baby foods and in mineral and vitamin tonics and pills.
Copper has a wide spectrum of effectiveness against the many biological agents of timber and fabric decay. It renders them unpalatable to insects and protects them from fungus attack. Copper sulphate has been in use since 1838 for preserving timber and is today the base for many proprietary wood preservatives.
The discovery more than 80 years ago that many algae are highly susceptible to copper, led to the use of copper salts by water engineers to prevent the development of algae in potable water reservoirs. They are also employed to control green slime and similar algal scums in farm ponds, rice fields, irrigation and drainage canals, rivers, lakes and swimming pools.
Another well known use for copper compounds is as a molluscicide for the control of slugs and snails. Less than one part of copper per million parts of water can control disease-transmitting aquatic snails, which are responsible for schistosomiasis or bilharzia in humans in tropical countries and fascioliasis or liver fluke of animals in both tropical and temperate climates.