AM A 



AMB 



alumrstone, a siliceous subsulphate of 

 alumina. Alum-slate is a rock, from 

 which alum is prepared. 



Rock alum is a variety of alum 

 brought from Roccha, formerly Edessa, 

 in Syria Roman alum is the purest 

 variety of alum, containing no ammonia 

 in its composition. Ammonia alum is a 

 double salt, consisting of the sulphates of 

 ammonia and of alumina. Soda alum is 

 a double salt, consisting of the sulphates 

 of alumina and of soda. Iron alum, 

 manganese alum, and chrome alum are 

 salts of alumina, to which the generic 

 term alum is applied, their specific dif- 

 ferences being denoted by the name of 

 the metallic peroxide which they respect- 

 ively contain. 



ALU'MINA. The earthy oxide of 

 aluminum ; a primitive earth, constitut- 

 ing the plastic principle of all clays, loams, 

 and boles, and hence termed argil, or 

 argillaceous earth. The name alumina 

 is derived from alumen, or alum, the salt 

 from which it is generally obtained in a 

 pure state. 



ALU'MINITE. The name by which 

 mineralogists designate the native hy- 

 drated subsulphate of alumina. 



ALU'MINUM. A metallic substance 

 resembling platinum, constituting the 

 base of alumina, and obtained from its 

 chloride by the action of potassium. 



ALUTA'CEOUS {aluta, tanned leather). 

 Of a pale brown colour, like that of tanned 

 leather. 



A'LVEOLATE {alveolus, a socket or 

 cavity). A term applied in Botany to a 

 surface covered with cavities, as the 

 receptacle of some species of the Com- 

 posita;. 



A'MADOU. A variety of the boletus 

 igniarius, found on old ash and other 

 trees. By means of nitre it is converted 

 into German tinder. 



AMA'LGAM (ci/xa, together, yajueo), 

 to unite). A compound of mercury with 

 other metals. A native amalgam, which 

 is of silver, occurs in Hungary and Swe- 

 den, in various forms. The amalgam 

 employed in electrical apparatus con- 

 sists of one part of tin, two of zinc, 

 and six of mercury, mixed with some 

 unctuous matter, and spread on silk or 

 leather. 



AMA'LGAMA'TION. The process of 

 making an amalgam, or mixture of mer- 

 cury with some other metal, for the pur- 

 pose of separating silver and gold from 

 their ores. The operation is founded on 

 the property which mercury possesses of 

 20 



dissolving these metals out of the mine- 

 rals with which they are associated. 



AMARANTA'CEiE. The Amaranth 

 tribe of Dicotyledonous plants. Herbs 

 or shrubs, with leaves simple, exstipu- 

 late ; flowers in heads or spikes ; stamens 

 hypogynous ; ovary superior ; fruit a 

 utricle ; seeds lentiform, with farinaceous 

 albumen ; embryo curved round the cir- 

 cumference. 



AMARYLLIDA'CE^. The Narcissus 

 tribe of Monocotyledonous plants. Gene- 

 rally bulbous, sometimes fibrous-rooted, 

 occasionally with a lofty stem. Leaves 

 ensiform ; calyx and corolla equally 

 coloured, superior; stamens 6; anthers 

 bursting inwardly ; stigma 3-lobed ; albu- 

 men fleshy or horny. 



AMA'RYTHRIN {amarus, bitter, ery- 

 thrin). A bitter extractive matter pro- 

 cured from erythrin, sometimes termed 

 erythrin bitter. 



AMAZO'NIAN STONE. A beautiful 

 green felspar, occurring in rolled masses 

 near the Amazon river. 



A'MBER. Succinum. A hard, brittle, 

 transparent or opaque substance, of an 

 orange colour, considered to be an indu- 

 rated vegetable juice, or concreted balsam. 

 By destructive distillation of this sub- 

 stance, a light yellow sublimate is pro- 

 cured, called amber camphor, or volatile 

 resin of amber. 



A'MBERGRIS {ambre gris, grey am- 

 ber). A sebaceous substance supposed 

 to be formed in the intestines of the 

 physeter macrocephalus, or spermaceti 

 whale, and sometimes found floating in 

 the sea, or thrown upon the shore. The 

 Japanese call it whale's dung. 



A'MBITUS [ambio, to encompass). 

 The circumference, or bounding line, of 

 a surface, as of a leaf. 



AMBLY'GONITE. A rare mineral, 

 consisting of a phosphate of alumina 

 and lithia, and occurring in granite, in 

 Saxony. It appears to be a species of 

 spodumene. 



A'MBREIN. A peculiar substance 

 obtained by digesting ambergris in hot 

 alcohol. By absorption of oxygen it is 

 converted into an acid called ambreic 

 acid. 



AMBULA'CRA {ambulacrum, an al- 

 ley). The narrow longitudinal portions 

 of the shell of the echinus, or sea-urchin, 

 which are perforated by small orifices, 

 traversed by tentacular suckers, and 

 alternated with the broad tuberculate 

 spine-bearing portions. 



A'MBULATORY [ambulo, to walk). 



