This section is from the book "A Text Book Of Materia Medica, Being An Account Of The More Important Crude Drugs Of Vegetable And Animal Origin", by Henry G. Greenish. Also available from Amazon: A Text Book of Materia Medica : Being an Account of the More Important Crude Drugs of Vegetable and Animal Origin.
Amber is the fossil resin of certain extinct Coniferous trees, chiefly of Finns succinifera, Conwentz. The term is a generic one, several varieties of amber having been distinguished, but that known as Baltic amber, or, better, succinite, is the only one of commercial importance.
The amber-yielding trees probably formed, in the early part of the period geologically known as the oligocene and belonging to the tertiary formation, extensive forests over the northern parts of Scandinavia. They contained oleo-resin ducts similar to those of Coniferous trees of the present day, and in addition frequently produced abnormal quantities of oleo-resin as the result of injuries, to which they appear to have been especially liable. The oleo-resin, hardened by exposure and liberated by the gradual destruction of the trees, was carried, towards the latter end of the oligocene period, from the position occupied by the forest and deposited in a bed of blue earth of considerable extent near the eastern shores of the Baltic. From this bed of earth which lies below the sea-level the amber is now recovered chiefly by mining, but some little is washed by the sea from the exposed surface of the stratum and thrown up by the waves on the shore.
Succinite is also occasionally found on the east coast of England, whither it has been brought by the sea.
Succinite occurs in pieces varying much in size and shape, usually with rounded edges and covered with a dark crust. Internally it is transparent, translucent, or quite opaque (cloudy amber), and of varying shades of yellow or brown. It exhales when warmed a slight but characteristic odour, and is almost tasteless. It is hard, breaking with a bright, conchoidal fracture that is sometimes glassy, sometimes opaque. It is partially soluble (about 30 per cent.) in alcohol, ether (about 20 per cent.), and chloroform (about 20 per cent.); it melts at 280° to 290°, at the same time decomposing and yielding water, succinic acid, and various tarry products.
That portion of succinite which is soluble in alcohol consists of free succino-abietic acid (itself a complex mixture the chief constituent being succino-abietinolic acid together with succoxyabietic acid, succino-silvic acid and succino-abietol) associated with a little bornyl succino-abietate. The part insoluble in alcohol, succinin, is a compound of succinic acid, with a resin-alcohol, succino-resinol. Succinite contains in addition traces of sulphur and of inorganic substances. By destructive distillation it yields a dark tarry oil accompanied by water; the former, separated from the watery fluid and redistilled, forms the genuine yellow oil of amber of commerce, which may be distinguished from a common substitute made from colophony by its higher specific gravity (0.926 to 0.930) and optical rotation (+ 23° to + 26°).