This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
This is the inner bark of Ulmus fulva, the slippery elm or red elm of this country, a large and handsome tree, growing throughout the Middle and Northern States. The bark is usually in flattish pieces or strips of variable size, of a tawny colour, somewhat reddish on the inner surface, very fibrous, so that it may be bent double without breaking, of a sweetish and agreeable odour, and a feeble not unpleasant taste. When chewed, it fills the mouth with mucilage. Sometimes it comes into the market cut into small pieces, and sometimes in the form of a light, loose, tawny powder, prepared by grinding.
The constituent upon which the bark depends for its medical virtues is a peculiar gummy matter, which it imparts readily to water, forming a very viscid solution. This is not, like gum, precipitated by alcohol, but affords copious precipitates with the solution both of the acetate and Subacetate of lead.
Slippery elm bark is one of the best and most agreeable of the demulcents, usually well received by the stomach. it is much used in this country both internally and externally. The infusion is a useful drink in catarrhal affections, diarrhoea, dysentery,.and diseases of the urinary passages; and is an excellent application in cases of external inflammation. Erysipelas, the severe forms of erythema, especially E. nodosum, the inflammatory stages of herpes, eczema, and impetigo, all afford indications for its use; and, indeed, it may be employed whenever, in consequence of local inflammation, there is a call for the application of cool water. As a demulcent, it is used in the form of infusion, which is most elegantly made out of the unpowdered bark.
Mucilage, or infusion of Slippery Elm Bark (Mucilago Ulmi, U. S.; infusum Ulmi, U S. 1850), is made by macerating a troyounce of the bruised bark in a pint of boiling water. it may be taken without limitation as a drink. Externally, it is applied by means of linen cloths, several times folded, which should be thoroughly wet with the infusion, and never allowed to become dry, even at their edges. Unfortunately, the strong incompatibility between it and both of the acetates of lead forbids their simultaneous use, though it might be strongly called for by the symptoms; and this is the greatest objection to the bark.