Boils. --Apply linseed poultice, or open it with a knife. If on the "seat of honor," apply a plaster spread on leather, and composed of equal parts of mercurial and opiate plaster. Do not use the knife. To those subject to boils use the following as a preventative: take nitrate of silver, from fifteen to twenty grains to the ounce, made into a wash, and paint the surface every night. This turns the skin black, but do not mind that.