_Counter-irritants_ are substances which produce irritation of the part to which they are applied, varying in degree from a slight redness to a blister or pustule. They are applied to the surface with a view of producing an irritation to relieve irritation or inflammation in some other or deeper seated part. They are a class of agents which we very seldom employ, and, hence, we shall notice only a couple of the most simple. MUSTARD (_Sinapis_). The flour of mustard, which is best adapted for domestic use, is employed in the form of a paste spread on cloth. It takes effect in a few moments; the length of time it remains in contact with the skin and the strength of the mustard determine the effect produced. HORSE-RADISH (_Cochlearia Armoracia_). The leaves are the parts used. Let them wilt and bind them on the part affected. They act nearly as energetically as mustard. DIAPHORETICS. _Diaphoretics_ are medicines which increase perspiration. Those which occasion profuse sweating are termed _Sudorifics_. The two terms indicate different degrees of the same operation. They constitute an important element in domestic practice, on account of the salutary effects which generally follow their action. Their operation is favored by warmth externally, and warm drinks, when they are not given in hot infusion. [Illustration: Fig. 127. Pleurisy-root. ] PLEURISY-ROOT (_Asclepias Tuberosa_), is also known as White-root, and Butterfly-weed. It is a valuable remedy, well adapted to break up inflammations and disease of the chest. _Dose_--Of infusion, one to two ounces; of fluid extract, one-fourth to one-half teaspoonful; of the concentrated principle, Asclepin, one to three grains. SAFFRON (_Crocus Sativus_). Golden Saffron. _Dose_--Of infusion (one drachm to a pint of water), one to two ounces. Sage (_Salvia Officinalis_). The warm infusion drunk freely is a valuable, domestic diaphoretic. [Illustration: Fig. 128. Virginia Snake-root. ] VIRGINIA SNAKE-ROOT (_Aristolochia Serpentaria_), is an efficient agent. _Dose_--Of infusion, one to two ounces; of tincture, one-fourth to one teaspoonful; of fluid extract, one-fourth to one-half teaspoonful. JABORANDI (_Pilocarpus Pinnatus_). Jaborandi increases the flow of saliva, causes profuse perspiration, and lowers the temperature of the body. In doses of from twenty to sixty drops of the fluid extract, administered in a cup of warm water or herb-tea on going to bed, we have found it very effectual for breaking up recent colds. We have also found it valuable in whooping-cough, in doses of from three to ten drops, according to the age of the child, given three or four times a day. The fluid extract may be obtained at almost any drug-store. [Illustration: Fig. 129. May-flower. ] MAY-WEED (_Maruta Cotula_), is also known as Wild Chamomile, and Dog-fennel. It is not much used, though it is a powerful diaphoretic. _Dose_--Of infusion, one to two ounces.