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A M M 



what ambergris consisted ; and Todd, in 

 his last edition of Johnson's Dictionary, 

 retains without any comment, or observa- 

 tion, the absurd opinions of former days, 

 stating that ' ' some imagine it to be the 

 excrement of a bird, which, being melted 

 by the heat of the sun, and washed off 

 the shore by the waves, is swallowed by 

 whales, who return it back in the condi- 

 tion we find it." Neumann absolutely de- 

 nies it to be an animal substance, as not 

 yielding in the analysis any one animal 

 principle. He concludes it to be a bitu- 

 men issuing out of the earth into the sea ; 

 at first [of a viscous consistence, but har- 

 dening, by its mixture with some liquid 

 naphtha, into the form in which we find it. 

 It is stated by Sir E. Home that this sub- 

 stance is only found in the unhealthy ani- 

 mal, but whether the cause or the effect 

 of disease is not well ascertained. When 

 the pieces of ambergris are large, they are 

 found to contain beaks of the sepia octo- 

 pedia, or cuttlefish, the usual food of the 

 spermaceti whale. Ambergris is a solid, 

 opaque, ash-coloured, inflammable, sub- 

 stance, variegated like marble, remarkably 

 light, its specific gravity ranging from 

 780 to 926 ; rugged, and, when heated, 

 emitting a fragrant odour. It is some- 

 times found in masses of two hundred 

 pounds weight and upwards. It breaks 

 easily, but cannot be reduced to powder ; 

 melts like wax, and is soluble in ether and 

 the volatile oils, and, assisted by heat, in 

 alcohol, ammonia, and the fixed oils. It 

 has been employed in medicine, but is now 

 quite laid aside. In consequence of its 

 fragrance it enters into the composition of 

 many articles of perfumery. 



A'MBIENT. (ambiens, Lat. am&iant, Fr. 

 ambiente, It.) Surrounding ; encompass- 

 ing ; investing. 



A'MBIT. (ambitus, Lat.) The compass or 

 circuit of any thing ; the line that en- 

 compasses any thing. 



A'MBITUS. In conchology, the circum- 

 ference or outline of the valves. 



AMBLY'PTERUS. A genus of fishes whose 

 duration was limited to the early periods 

 of geological formations ; and which are 

 marked by characters that cease after the 

 deposition of the magnesian limestone. 

 This genus occurs only in strata of the 

 carboniferous order, and presents four 

 species at Saarbriick, in Lorraine ; it is 

 found also in Brazil. The character of 

 the teeth in Amblyterus shews the habit of 

 this genus to have been to feed on decayed 

 sea-weed, and soft animal substances at 

 the bottom of the water; they are all 

 small and numerous, and set close toge- 

 ther like a brush. The form of the body, 

 being not calculated for rapid progression, 

 accords with this habit. The vertebral 



column continues into the upper lobe of 

 the tail, which is much longer than the 

 lower lobe, and is thus adapted to sustain 

 the body in an inclined position, with the 

 head and mouth nearest to the bottom. 

 This remarkable elongation of the supe- 

 rior lobe of the tail is found in every bony 

 fish of strata anterior to, and including, 

 the magnesian limestone. Buckland. 



AMBLYRHY'NCHUS CRISTATUS. The only 

 existing marine lizard now known. Lyell. 



AME'NT. } (amentum, Lat.) A catkin, one 



AMF/NTUM. S .kind of inflorescence. When 

 the bractese on the principal stalk are close, 

 and overlap one another, or are imbri- 

 cated with the flowers sessile in their 

 axillae, the spike is termed an amentum, 

 or catkin, and the peduncle is always 

 articulated with the main stem of the 

 plant. Aments, or catkins, are generally 

 pendent, while spikes are for the most 

 part erect. 



A'METHYST. (d/ueOvoroc, Gr. contrary to 

 wine, or drunkenness, so called from a 

 supposed virtue it possessed of prevent- 

 ing inebriation.) Quartz, coloured by a 

 minute portion of iron and manganese. 

 The finest specimens come from India, 

 Spain, and Siberia, but the amethyst is 

 commonly found in most countries. The 

 amethyst is a transparent gem of a purple 

 or violet-blue colour ; it is sometimes 

 found naturally colourless, and may at 

 any time be made so by putting it into 

 the fire. When deprived of its colour it 

 greatly resembles the diamond. Some 

 derive the name amethyst from its colour, 

 which resembles wine mixed with water ; 

 whilst others, with more probability, 

 think it obtained its name from its sup- 

 posed virtue of preventing drunkenness ; 

 an opinion which, however imaginary, 

 prevailed to that degree among the 

 ancients, that it was usual for great 

 drinkers to wear it about their necks. 



AMETHY'STINE. Possessing the properties 

 of an amethyst ; of the colour of an 

 amethyst. 



A'MIANTH. 1 (amiante, Fr. amianto, It.) 



AMIA'NTHUS. $ A variety of asbestos, 

 or flexible asbestus ; an incombustible 

 mineral composed of very delicate and 

 minute fibres, which were, sometimes, 

 according to Dioscorides, worked into a 

 cloth capable of resisting the action of 

 fire. 



AMIA'NTHIFORM. Having the form or 

 likeness of Amianthus. 



AMMONA'CEA. According to the arrange- 

 ment of De Blainville, a family of the order 

 Polythalamacea. It embraces the genera 

 Discorbis, Scaphites, Ammonites, and 

 Simplegas. In the Lamarckian system 

 the ammonacea is a family of the order 

 Polythalamous cephalopoda, embracing 

 c 2 



