This book teaches you how to make Penicillin. Sir Alexander Fleming discovered the bacteria-killing properties of penicillin while conducting research at St. Mary's Hospital in London in the late 1920s. . Upon returning to his disorganized lab from a weekend vacation, Fleming noticed that one of the Petri dishes was uncovered and a blue-green mold was growing inside. Rather than tossing the contaminated dish into the trash, he looked carefully and observed that the mold had killed bacteria growing nearby.