Litchfield, Isaac W, Massachusetts Institute of Technology. Society of Arts · Boston, Mass. : The Society · leaf 141
Science Conspectus 131 … Diagram representing symbolically the transformation of part of the radium chain of elements. The first circle represents a radium atom which when it "explodes" throws off an atom of helium and what remains becomes an atom of another element called, for want of a better name, "radium emanation."…
Science
Internet Archive · Smithsonian Libraries · Public domain (published before 1931). Free to use for anything.
