[Illustration: The Grant Memorial consists of bronze statues on
marble bases; although the statues were cleaned, the staining on the
marble remains.]
This memorial, dedicated in 1922, consists of a group of bronze
sculptures mounted on marble bases. Bronze weathers outdoors if it is
not cleaned and waxed regularly. Like stone, bronze dissolves where it
is exposed to rainfall, developing a green color and a pitted surface,
and it also alters in sheltered areas, with accumulation of a blackened
layer. The most notable stone deterioration visible here is the green
stain on the marble bases, caused by runoff from the weathered bronze.
The green stain does not damage the marble, but it is unattractive, and
there are no methods currently available to remove the stain without
damaging the marble.
[Illustration: The light-green color on the bronze statues at the
Grant Memorial is typical of the way bronze weathers when it is
exposed to acidic rain; the rain dissolves some of the metal and
causes staining of the white marble bases.]
Continue south, crossing Maryland Avenue, to the Botanic Gardens.