Under the name of Juglans or Butternut, the U. S. Pharmacopoeia recognizes the inner bark of the root of Juglans cinerea, or common white walnut tree of this country, which grows in Canada, and through the northern portions of the United States. When first taken from the tree, it is white, but soon changes colour, becoming at first yellow, and ultimately of a dark walnut-brown. A decoction of the bark is purgative; but it is the extract that is almost exclusively employed.

Extract of Butternut (Extractum Juglandis, U. S.) is directed, in the U. S. Pharmacopoeia, to be prepared by evaporating an infusion of the bark, which is preferably made by the process of displacement. Care should be taken not to carry the heat too far. The extract would probably be more effective if diluted alcohol, instead of water, were employed as the menstruum. it is hard and brittle, of a black colour, a sweetish, not unpleasant smell, and a bitter, somewhat astringent taste. The greater part of it is soluble in water.

It is a mild cathartic, said to resemble rhubarb in its mode of operation, and applicable to similar purposes. it was employed to a considerable extent, during our revolutionary war, by Dr. Rush and others connected with the military service of the country, when the scarcity of rhubarb induced them to search for a substitute for that cathartic. it may be used as a laxative in the dose of from five to ten grains, as a purgative from twenty to thirty.