Raw cotton is used in compounding gun cotton or explosive cotton, also named pyroxylin, and this is used to make collodion, so extensively employed in medicine.
Pyroxylin is made by treating cotton with equal parts of nitric and sulphuric acids, then washing with water till the latter ceases to give a precipitate with chloride of baryta; then dry in the air.
Collodion is made by dissolving 5 grams of pyroxylin in the following mixture:
| Sulphuric ether, rectified | 75 grams. |
| Alcohol at 95° | 20 grams. |
Filter.
Elastic collodion:
| Canada Balsam | 1.50 grams. |
| Castor oil | .50 grams. |
| Collodion | 30.00 grams. |
Mix.
Botanical Description.—A plant 2–3° high, of herbaceous stem, branches sparsely covered with small, black points; leaves cleft at their base, with 5 lobules and a small gland on the midrib. Petiole long with 2 stipules at the base. Flowers axillary, solitary. Calyx double; the outer portion divided in 3 parts, heart-shaped, and each with 5–9 long, acute teeth. Corolla bell-shaped, of 5 petals, pale yellow or turning rose color, purple at the base. Stamens many, inserted on a column. Stigma in 4–5 parts. Ovary of 3–5 compartments. Seeds enveloped in the fiber.
Habitat.—Batangas, Ilocos.