Book excerpt: Joseph Priestly, Radical Thinker offers a unique look into the achievements of this scientific giant, whose work helped provide the foundation for chemistry research. The book is the catalog that accompanies an exhibit of historical images and artifacts that commemorated the 200th anniversary of the death of Priestly and includes essays by historian Robert Anderson and Marjorie Gapp, curator of art and images at Chemical Heritage Foundation. Gapp and Mary Ellen Bowden, with Lisa Rosner, also examine the historical significance of the many objects and artifacts found in this fascinating collection.