This section is from the book "Botanic Drugs Their Materia Medica, Pharmacology and Therapeutics", by Thomas S. Blair. Also available from Amazon: Botanic Drugs, Their Materia Medica, Pharmacology and Therapeutics.
Marigold, calendula officinalis. Official U. S. P., Eighth Rev., but in no other country. Deleted from ninth revision and incorporated in the National Formulary. The tincture is used externally much as is arnica; but it is superior to arnica as a wet dressing in cases where without such applications a cicatrix would form too rapidly. It may be used in most any strength, diluted with water. A good dressing is calendulated boric acid, and a good wet dressing is saturated boric acid solution to which tr. or fl. calendula is added. Open wounds and burns may be so dressed. The fl. is also combined with solution of boroglycerid. The stimulation of calendula makes it available in the local treatment of various chronic lesions. In my hands calendula has been satisfactory as a minor dressing, but not when used alone. It stains yellow, which is an objection.