Prep. By immersing cotton wool in equal parts of sulphuric acid and nitric acid, afterwards well washing, and drying in a water-bath. (A weaker acid is required for making a soluble pyroxylin.)

Prop. &, Comp. It is readily soluble in a mixture of ether and rectified spirit, leaves no residue when exploded by heat, it resembles cellulin in composition, with a certain number of equivalents of hydrogen, replaced by peroxide of nitrogen (C36 H22, 8 No4,O80). It is used in the Pharmacopoeia for the preparation of collodion.

Use. Cotton is used as an application to burns and scalds, diminishing the inflammation, and aiding recovery probably from protecting the surface: occasionally employed in erysipelas. [The root is said to promote the contractions of the uterus in the parturient female. A decoction is made by boiling four ounces of the inner bark of the root in a quart of water until it is reduced to a pint. Dose, a wine-glass full every twenty or thirty minutes.]