Salix nigra bark of the tree contains salicylic acid, a chemical compound similar to aspirin (acetylsalicylic acid). It may also be used as an environmental restorative. Swamp trees in general are, by necessity, good at surviving and thriving in areas where highly mobile environmental toxins are present. Black Willow is very resistant to herbivory and flooding and is also a fantastic erosion control tool. Thus, it is useful for any sort of marshland stabilization or restorative as long as the roots don’t penetrate any clay liner that may be in place. In a relatively extensive phytoremediation study, "Salix nigra" demonstrated some success
Lune of Hippocrates circle. He proved that the lune bounded by the arcs labeled "E" and "F" in the figure has the same area as triangle "ABO". This afforded some hope of solving the circle-squaring problem, since the lune is bounded only by arcs of circles. Heath concludes that, in proving his result, Hippocrates was also the first to prove that the area of a circle is proportional to the square of its diameter. Hippocrates' book on geometry in which this result appears, "Elements", has been lost, but may have formed the model for Euclid's "Elements". Hippocrates' proof was preserved through the "History