Tara Hensel, age 14, of Baton Rouge, La., for her question:

WHO DISCOVERED ANTISEPTICS?

A British surgeon named Joseph Lister discovered antiseptics in 1865.

Earlier, Louis Pasteur had discovered that bacteria caused fermentation and Lister saw that these microscopic organisms were also the cause of putrefaction in wounds following many of his operations.

At first Lister thought that germs got to the wound through contact with air, so he used carbolic acid to seal the wounds. But even though the acid killed the germs, it left deep scars.

Additional research by Lister led him to the conclusion that the germs were carried by the instruments and the hands of the people in the operating room. Using antiseptics on the hands, dressings, sponges, bandages and all of the instruments, Lister proved to his medical associates that he had the answer: antiseptics kill bacteria.

By the 1880s Lister's antiseptic theories had become widely accepted. In 1897 he was made a baron by one of his patients, Queen Victoria.