Amber

Amber is the most familiarly known of all the resins on account of its long use in its natural state for ornamental purposes. Amber beads have not infrequently been found in early British graves; on the Continent these and other ornaments of amber have often been obtained from ancient interments. At Naples I was shown some years ago a very large number of antique fibulæ carved out of this substance: they had just been disinterred from Etruscan tombs. Such amber has often become brittle and far more soluble in the usual solvents, especially so far as regards the surface layers; but in other instances the preservation of the properties of this resin has been complete. The chief localities where amber is found are the Prussian shores of the Baltic Sea (particularly between Konigsberg and Memel) and the neighbouring plains; it has been found in veins, and is regularly quarried. Some amber, much of it having a dark colour, is found near Catania, Sicily. Near Lemberg (Galicia in Austria) nodules of amber occur in rock.

It occurs in several places in Denmark, Sweden, Norway, and France. In the British Museum collection of minerals there is a fine mass from Cambridge. Excellent specimens occur in comparative abundance on the seashore at Southwold in Suffolk, and at several other places on the Suffolk, Norfolk, and Essex coasts. The dark fossil resin found in Birma, often in large masses, is not identical with Baltic and English amber. The same observation may be made with respect to the so-called ambers of Travancore in the East Indies, and of the Isle of St. Louis, Senegambia, Africa. In fact, amber, instead of being, as commonly stated, the fossil resin of a single species of tree of Tertiary age, has obviously been derived from no inconsiderable number of different plants. Goppert, so long ago as 1853, satisfied himself that at least eight species of plants besides Pinites succinifer have afforded this fossilized resin: he also enumerated 163 species of plants as represented by remains in amber; many others have been since recognised. Amber has a specific gravity of about 1.07; its hardness is 2 1/2 on the ordinary mineralogical scale. In most of the usual solvents of resins it is either insoluble or but partially soluble.

When heated quickly on a spatula it splits up and then fuses into a viscous liquid, the drops which are formed rebounding as they fall upon a cold surface: this behaviour serves as a distinguishing test between amber and copal. When crushed amber is heated in a retort it fuses at about 280° C. (536° F.), gives off water, succinic acid, marsh gas, a mixture of liquid hydrocarbons (known as oil of amber), and, finally, at a very high temperature, a yellow substance having a wax-like consistence. Sulphuretted hydrogen and other sulphur compounds are also evolved in small quantity, for amber, like several other fossil resins, contains a little sulphur (sometimes 1/2 a part in 100) in organic combination. Amber breaks with a conchoidal fracture. When fragments of amber are being ground or powdered they emit an aromatic odour. On being rubbed amber becomes negatively electric in a high degree.

It is probable that true amber consists mainly of a single resin (85 to 90 percent of the whole) represented by the empirical formula nC₁₀H₁₆O. Small quantities of two other resins which are soluble in alcohol and ether, of a liquid hydrocarbon, and of succinic acid, are associated with the main constituent, which has received the mineralogical name 'succinite.'

The classical names for amber were lyncurium, elect rum, and succinum. In early mediaeval times amber was called vernix, a term which at first was applied also to sandarac, and later in the fifteenth century to san-darac only, when amber was designated as glas, or glassa. In modern French amber is distinguished from ambre gris as ambre jaune, although it is also known as karate and succin. It is the Bernstein of the Germans. The word 'amber' is probably derived, through the Spanish, from the Arabic anbar, a term applied to ambergris.