Court Plaister

Harriet confesses to Emma that when she thought she was in love Mr. Elton, she would keep mementos that, to her, symbolized what their love could someday be. Now that he is married to another woman, she wants to get rid of these items so that she can be free and clear of her feelings of him forever. One of the things she kept was court plaister. Mr. Elton apparently cut himself and needed it to stop the the bleeding. Emma is in a state of both "wonder and amazement" that Harriet would keep such an object (227). There is a definite reason for these feelings. Court plaister was "an early form of sticking plaster, made from small pieces of silk, coated with a substance which became sticky when wetted." In essence, Harriet was saving a band-aid Mr. Elton had absentmindedly rolled around in his hand because he didn't need it. If anyone did that today, it would be considered mildly disgusting.
To learn more about the court plaister Harriet saves- http://austenonly.com/2010/01/14/austenonly-emma-season-harriets-most-precious-treasures/