AMBER 535 



AMBER. 



This material, so much used for ]iersonal ornaments, is not strictly speaking a mineral 

 at all, being of vegetable origin, and consisting of the more or less considerably altered 

 resin of extinct trees. It resembles minerals in its occurrence in the beds of the earth's 

 crust, and for that reason may be considered, like other varieties of fossil resin, of which it 

 is the most important, as an appendix to minerals. 



Nature and Chaeactees. — It is proposed to deal first with true amber or amber 

 proper, the succinite of mineralogists, the principal locality for which is the district of 

 Samland, in the province of East Prussia, and to conclude with a consideration of other 

 resins, which are similar to amber and used for the same purposes, but which are of much 

 rarer occurrence. 



In respect to its chemical composition, amber, like other resins, consists essentially 

 of carbon, hydrogen, and oxygen. These elements are combined together in somewhat 

 variable proportions, but on an average the material contains 79 per cent, of carbon, 10-5 

 per cent, of oxygen, and 10"5 per cent, of hydrogen, a composition which is represented by 

 the chemical formula C^gH^gO. A small amount of sulphur is sometimes present, and a little 

 inorganic material, which remains behind as ash when the amber is burnt. Pure amber 

 contains only about ^ of a per cent, of ash, but when enclosures of foreign substances are 

 present this percentage rises considerably. 



Amber is not homogeneous nor of simple constitution. Apart from the inorganic ash 

 it contains several substances which can be separated by chemical means. By distillation is 

 obtained a small quantity of oil of amber (an ethereal oil) and some succinic acid ; the 

 latter is an especially characteristic constituent of true Prussian amber, in which it is always 

 present, though in variable amount. Perfectly clear and transparent specimens contain 

 3 to 4 per cent, of succinic acid, cloudy specimens contain more, and in frothy amber there 

 may be as much as 8 per cent. By treating the fine powder with alcohol, ether, and other 

 solvents, four resinous substances, differing from each other in chemical composition and in 

 melting-point, may be separated. The insoluble residue, amounting to from 44 to 60 

 per cent, of the whole, is a bituminous substance, the so-called amber-bitumen. 



Amber is perfectly insoluble in water, and is only slightly attacked after a contact of 

 some duration with alcohol, sulphuric ether, acetic ether, and other solvents. This affords 

 an important distinction between true amber and the many similar resins, which are so 

 often substituted for it, the latter being quickly attacked by alcohol and the other solvents 

 mentioned above. In concentrated sulphuric acid finely powdered amber is perfectly 

 soluble even in the cold, and it is completely decomposed by boiling nitric acid. 



When amber is heated it softens, swells, and gives off a characteristic and pleasant 

 odour. Between 280° and 290° C, that is to say at a higher temperature than is the case 

 with other resins, it melts, and is at the same time decomposed with the evolution of the 

 two volatile constituents, oil of amber and succinic acid. These substances are given off in 

 the form of white fumes and are sometimes accompanied .by a small amount of water 

 vapour. . The fumes have the same peculiar aromatic odour, and owing to the presence of 

 succinic acid in them act as an irritant when inhaled into the respiratory passages, causing 



