In 1857, a Canadian Professor at the University of Montreal invented the green ink that would be used in United States’ currency. The ink, composed of chromium trioxide is perfect for monetary use as it cannot be destroyed by either an acid or strong base and it is not able to be properly photographed. It did not take long for the United States to see the benefits of the ink and by 1862 “greenbacks” were in circulation. This 1857 silver three-cent coin recalls a monetary invention that remains in use to this day.