Part 61. Poisonous drugs comprise substances which depend for their power upon certain volatile oils, camphors, resins, alkaloids, and some other classes of compounds which we shall not need to discuss.

A considerable number of the medicinal plants containing poisonous volatile oils we have already considered under the head of food-adjuncts. Cinnamon, wintergreen, clove, peppermint, spearmint, thyme, nutmeg, horseradish, mustard, allspice, and black pepper, will be recalled as examples of more or less powerful poisons which nevertheless in very small amount are grateful and often beneficial additions to our food. They are used in medicine partly for their attractive flavor, partly for their stimulating or irritating effect, and partly as antiseptics.1

1 An antiseptic is a substance which is poisonous to the microscopic germs, or septic organisms as they are called, which cause fermentation, putrefaction, and certain diseases.