To Clean Brass and Copper
April 23rd, 2017
Scrape a little rotten-stone fine, and make into a paste with sweet oil. Rub on with a piece of flannel; let it dry, and polish with a chamois-skin. Copper is cleaned either with vinegar and salt mixed in equal parts, or with oxalic acid. The latter is a deadly poison, and must be treated accordingly.
Source: The Easiest Way in Housekeeping and Cooking, H. Campbell