"Mucilage, albumen, or gluten, extractive, a bitter principle, an
essential oil, nitrate of potass, which occasions its deflagration,
muriate of potass, and a peculiar proximate principle, upon which the
virtues of the plant are supposed to depend, and which has therefore
been named _Nicotin_. This peculiar principle is considered by some, as
approaching the essential oil in its properties. It is colorless, has an
acrid taste, and the peculiar smell of tobacco; and occasions violent
sneezing. With alcohol and water it forms a colorless solution, from
which it is precipitated by a tincture of galls. Tobacco yields its
active matter to water and proof spirit, but most perfectly to the
latter; long boiling weakens its powers. A most powerful oil may be
obtained by distillation, and separating it from the surface of the
water on which it floats."