The Physiomedical Dispensatory by William Cook, M.D., 1869    

CHONDRUS CRISPUS

CARRAGEEN, IRISH MOSS            

Description:  Natural Order, Algaceae. Genus CHONDRUS:  Frond cartilaginous, nerveless, flattened, nearly cylindrical at the base, dichotomously divided. C. CRISPUS:  Fronds thick, three to ten inches long, in wedge-shaped segments, narrow, cloven deeply; the margins tough, almost horny when dry, of a deep purplish-brown color, becoming a dirty yellowish-white when dried.

This species of moss is found on stones along the sea-shore of western Ireland, and also of England and Scotland. It appears in commerce as crisp; twisted, horny-looking masses, which swell up slowly in cold water, and nearly dissolve in boiling water. It contains a large amount of gum-like mucilage, with small quantities of starch and other substances. The mucilage forms a handsome jelly, and is quite nutritious.

Properties and Uses: Carrageen is used for its demulcent influence in bronchial and pulmonary irritation, diarrhea and dysentery, and irritability of the kidneys and bladder. It is most available in recent colds and coughs, where it may be used freely in warm decoction. The decoction is made by macerating half an ounce of moss for ten minutes in warm water; then boiling fifteen minutes in three pints of water, straining, sweetening to taste, and flavoring with lemon or some spices. This may be drank freely. When used chiefly for nourishment, milk should be substituted for the water. The jelly is made by using two ounces of the moss to three pints of water, adding half a pound of sugar; and when milk is thus used instead of water, a pleasant and light blanc-mange is produced.

 Medical Herbalism journal and medherb.com