AMAUROSIS. Syn. Gutta serena, Suffusio nigra. A diminution or total loss of sight, arising from paralysis of the retina or optic nerve.
AM′BER. Syn. Elec′tron, Gr.; Elec′trum, Suc′cinum (Ph. D.), L.; Ambre, Succin, Fr.; Bernstein, Ger.; Lynx-stone†, La′pis lyn′cis†, L. A well-known yellowish, semi-transparent, fossil resin, of which trinkets and the mouth-pieces of pipes are commonly made.
Nat. hist., &c. Amber is found in detached pieces on the sea-coast, and is dug up in diluvial soils. That of commerce comes chiefly from the southern coasts of the Baltic, where it is cast ashore between Königsberg and Memel; and from Ducal Prussia, Saxony, Poland, Sicily, and Maryland (U.S.), where it is dug out of beds or mines. It has also been found on the shores of Norfolk, and small pieces are occasionally dug up in the gravel pits round London. It is probably an antediluvian resin; and when found on the coast, is supposed to be disengaged, by the action of the sea, from neighbouring beds of lignite or fossil coal. Much diversity of opinion for a long time prevailed amongst naturalists and chemists as to the origin of amber, some referring it to the vegetable, others to the mineral, and some even to the animal kingdom; its natural history and analysis affording something in favour of each. The vegetable origin of amber has, however, been recently shown by various facts, and is now generally admitted. According to Sir David Brewster, its optical properties are those of an indurated vegetable juice. (‘Ed. Phil. Journ.,’ ii.) Insects and fragments of vegetables are frequently found imbedded in it; and this in a manner which could only have occurred when the resin was a viscid fluid. Microscopical researches have led to the conclusion that it is the production of some species of pine, closely allied to the pinus balsamea. (‘Entom. Trans.,’ i & ii.)
Manuf. Amber is WORKED in a lathe, POLISHED with whiting and water or rottenstone-and-oil, and FINISHED OFF by friction with flannel. During the operation the pieces often become hot and electrical, and fly into fragments; to avoid which they are kept as cool as possible, and only worked for a short period at a time. The workmen are said to often suffer considerably from electrical excitement. Amber is JOINED and MENDED by smearing the surface of the pieces with linseed or boiled oil, and then strongly pressing them together, at the same time holding them over a charcoal fire, or heating them in any other convenient way in which they will not be exposed to injury. The commoner varieties are HARDENED and rendered CLEARER, either by boiling them in rape oil for about 24 hours, or by surrounding the pieces with clean sand in an iron pot, and exposing them to a gradually increasing heat for 30 or 40 hours. During this process small fragments are kept in the sand at the side of the pot, for the purpose of occasional examination, lest the heat be raised too high, or be too long continued.
Prop., &c. Hard; brittle; tasteless; glossy; generally translucent, but sometimes opaque, and occasionally, though rarely, transparent; colour generally yellow or orange, but sometimes yellowish-white; becomes negatively electric by friction; smells agreeably when rubbed or heated; fracture conchoidal and vitreous or resinous; soluble in the pure alkalies, and, without decomposition, in oil of vitriol, which then becomes purple; insoluble in the essential and fixed oils without long digestion and heat; soluble in chloroform; melts at about 550° Fahr.; burns with a yellow flame, emitting at the same time a peculiar fragrant odour, and leaving a light and shiny coal. By dry distillation it yields inflammable gases, a small quantity of water, a little acetic acid, a volatile oil (OIL OF AMBER; O′LEUM SUC′CINI, L.) at first pale, afterwards brown, thick, and empyreumatic, and an acid (SUCCIN′IC ACID; ACIDUM SUCCIN′ICUM, L.); with residual charcoal 12 to 13%. Sp. gr. 1·065 to 1·09, but usually about 1·070. It cannot be fused without undergoing more or less chemical change.
Ident. Amber may be known from mellite and copal, both of which articles are occasionally substituted for it, by the following characteristics:—1. Mellite is infusible by heat, and burns white:—2. A piece of COPAL, heated on the point of a knife, catches fire, and runs into drops, which flatten as they fall:—3. Amber burns with spitting and frothing, and when its liquefied particles drop, they rebound from the plane on which they fall (M. Haüy):—4. Neither mellite nor copal yields succinic acid by distillation; nor the agreeable
odour of amber when burnt; nor do they become so readily electric by friction.
Uses. It is chiefly made into mouth-pieces for pipes, beads for necklaces, and other ornaments and trinkets. It is also used as the basis of several excellent varnishes. In medicine, it was formerly given in chronic coughs, hysteria, &c.—Dose (of the powder), 10 to 60 gr.
Remarks. The finer sorts of amber fetch very high prices. A piece 1 lb. in weight is said to be worth from 10£ to 15£. 5000 dollars a few years since were offered in Prussia for a piece weighing 13 lbs., and which, it was stated by the Armenian merchants, would fetch from 30,000 to 40,000 dollars in Constantinople. It is more valued in the East than in England; and chiefly on account of the Turks and other Orientals believing it to be incapable of transmitting infection. In the royal cabinet, Berlin, there is a piece weighing 18 lbs., supposed to be the largest ever found. The coarser kinds alone are employed in medicine, chemistry, &c.
Amber, Ac′id of* (ăs′-). Succinic acid.