To Cure Ringworm
To one part of sulphuric acid add from sixteen to twenty parts of water. Use a brush or feather, and apply it to the part night and morning. A very few dressings will generally cure. _ If the solution is too strong, dilute it with more water, and if the irritation is excessive, rub a little oil or other softening applicant, but avoid soap.
Source: Four Hundred Household Recipes (no copyright date)