Bald 's eyesalve is a 10th century brew used by Anglo Saxons to treat styes . researchers found it killed 90 % of bacteria on scraps of mercury - contaminated metal . Ingredients had little effects unless they were brought together in a batch . Brewing method - using a brass catalyst - was also found to be important .
Bald 's eyesalve is a 10th century brew used by Anglo Saxons to treat styes . Scientists found it killed 90 % of bacteria on scraps of MRSA-infected skin . Ingredients had little effects unless they were brought together in a mix . Brewing method - using a brass vessel - was also found to be important .