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 pith of the small terminal branches of our indigenous Sassafras officinale, or common sassafras tree. it is in very slender cylindrical pieces, of various lengths, extremely light and spongy, white with sometimes a yellowish tinge, inodorous, and of a mucilaginous and very slightly aromatic taste. it contains a large proportion of mucilaginous matter, which it readily imparts to water hot or cold, forming a ropy, but not very tenacious solution. The infusion is not precipitated by alcohol, very slightly by solution of acetate of lead, but copiously by the Subacetate, with which, therefore, it is incompatible.
The infusion of sassafras pith is a delicate demulcent preparation, which may be used externally and internally for the general purposes of the class. But it is most employed as an application to the conjunctiva in ophthalmia, in which it was strongly recommended by the late Dr. Physick, and is certainly sometimes very beneficial. in dry states of the inflamed or irritated conjunctiva, it supplies the place of the natural mucus in lubricating the membrane, at the same time that it in some measure protects it from direct contact with the air. The mucilage, too, is itself so bland as not to irritate even the delicate surface of the eye. it should be applied constantly over the closed lids, upon linen rags, and should also be allowed free access to the conjunctiva. it may be used externally with solution of the acetate of lead, but not with that of the Subacetate.
Mucilage, or infusion of Sassafras Pith (Mucilago Sassafras U. S.; infusum Sassafras Medulla, U. S. 1850), is made by macerating for three hours two drachms of the pith in a pint of cold water. it may be drank ad libitum.