Popular medical remedy of the 18th century recommended by philosopher, George Berkeley.
Tar water was made by putting a quart of cold water and a quart of tar together, mixing them, and then allowing the tar to settle. A glass of the clear water that remained behind was then drawn off and mixed with an equal amount of fresh water. Berkeley developed his own procedure of producing tar water by mixing a gallon of water with a quart of tar and allowing the mixture to stand for 48 hours. In 1744 he authored a book on the subject, Siris, a Chain of philosophical reflections and Enquiries on the Virtue of Tar Water. Berkeley first used tar water during a local outbreak of smallpox. He found that those who took tar water either did not develop smallpox at all or developed only a mild case of the disease. He also recommended the preparation to sailors for the prevention of scurvy, to students cramped up in unhealthy study quarters, and to the general public for the prevention and treatment of a variety of ailments form hysteria to the plague.