E C H 



[81 ] 



E L E 



depressions, of a circular form, with cen- 

 tral tubercles. Parkinson. 



ECHINARA'CHNIUS. (from e%u>o and 

 apaxvij, Gr.) A genus of echini be- 

 longing to the class Pleurocysti. To this 

 genus Klein gave the name Arachnoides. 



ECHINOCO'RYS. A genus of fossil echinites, 

 thus named by Leske, belonging to the 

 class of Catocysti. This genus com- 

 prises all those echinites which Klein di- 

 vided into Galeae and Galeolse. There 

 are several species. 



ECHINODI'SCUS. The name given by Brey- 

 nius to a section of echini belonging to 

 the class Catocysti. The echinodiscus 

 is of a depressed discoidal figure, whence 

 it has its name, nearly flat on both sides. 

 Echinodisci are found both recent and 

 fossil. There are many species. 



EDA'CIOUS. (from edax, Lat.) Predaci- 

 ous ; voracious ; rapacious. 



EDENTA'TA. The sixth order of Mamma- 

 lia, in Cuvier's arrangement, or quadru- 

 peds without front teeth. This order 

 comprises three tribes, Targigrada, Eden- 

 tata ordinaria, and Monotremata. 



EDENTA'TED. (edentatus, Lat. edente, Fr. 

 edentato, It.) Without teeth. 



E'DIBLE. (from edo, Lat.) That may be 

 eaten ; fit for food. 



EDI'NGTONITE. A mineral, resembling 

 some varieties of felspar and prehnite. 



EFFERVESCE, (ejfervesco, Lat.) To be 

 in a state of intestine motion from the 

 generation of gas, which is continually 

 rushing to the surface and making its 

 escape. 



EFFERVE'SCENCE. (effervescentia, Lat. 

 effervescence, Fr. effervescenza, It.) That 

 commotion which takes place in fluids 

 when gas is generated, rises to the sur- 

 face in small bubbles, and escapes ; it is 

 accompanied by a kind of hissing noise. 



EFFLORE'SCENCE. (effloresco, Lat. efflo- 

 rescence, Fr. efflorescenza, It.) 



1. Prodiiction of flowers. 



2. Excrescences in the form of flowers. 



3. The pulverescence of crystals on expo- 

 sure to the atmosphere. 



EFFLORESCENT. 



1. Shooting out in the form of flowers. 



2. Becoming pulverulent on exposure to 

 the atmosphere ; the reverse of deliques- 

 cent. 



E'FF;LUX. )(effluxio, Lat) The act of 



EFFH/XION. 5 flowing out ; as the efflux 

 of a river or tide. 



EFFO'SSION. (from effodio, Lat.) The 

 digging out of the earth, as of fossils, &c. 



EFFU'SE. In conchology, a term applied 

 to shells where the aperture is not whole 

 behind, but the lips are separated by a 

 gap. 



EGE'RIA. A genus of fossil bivalves belong- 

 ing to the tertiary formation. 



ELA'OLITE. (from eXat'a, an olive, and 

 Xi'flof, a stone.) A sub-species of pyra- 

 midal felspar, known also as fettstein, or 

 fatstone, a name given to it from its 

 greasy feel. 



ELA'STIC MINERAL PITCH. Called also 

 elaterite and mineral caoutchouc ; a brown, 

 massive, elastic variety of bitumen : it 

 consists of about 52 per cent, of carbon, 

 40 percent, of oxygen, 0'15 of nitrogen, 

 and 8 per cent, of hydrogen. 



ELA'TERITE. Another name for elastic 

 mineral pitch. 



ELE'CTRUM. Argentiferous gold ore, a 

 variety of hexahedral gold, of a pale brass- 

 yellow colour. Pliny informs us that it 

 was a mixture of gold and silver, and thus 

 writes, " Omni auro inest argentum vario 

 pondere. Ubicunque quinta argenti por- 

 tio est, electrum vocatur." It has been 

 attempted to prove that platinum is the 

 electrum of the ancients, but such is not 

 the case. 



ELEME'NTARY. (element arius, Lat. ele- 

 mentaire, Fr. elementario, It.) Uncom- 

 pounded; uncombined; simple; primary. 



ELEME'NTARY SUBSTANCES. There are 

 fifty -five simple, or elementary substances 

 at present known, that is, substances 

 which, under the conditions yet applied 

 to them, are found to be incapable of fur- 

 ther analysis, and are therefore called 

 simple, or elementary, substances. Five 

 of these exist in a separate state as gases, 

 namely, oxygen, hydrogen, chlorine, azote, 

 and fluorine ; the last, however, of these 

 has not yet been obtained in a separate 

 state, and is only known to be a distinct 

 substance from the qualities of the com- 

 pounds it forms with other matter. Seven 

 are non-metallic solids and liquids, name- 

 ly, sulphur, phosphorus, selenium, boron, 

 carbon, bromine, and iodine ; of these, 

 the two last, bromine and iodine, are 

 either gaseous, liquid, or solid, according 

 to the temperature. Sulphur, phospho- 

 rus, selenium, boron, and carbon, are 

 solids, but differ from the remaining forty- 

 one in being non-conductors of electricity. 

 Of the remainder, thirteen are metallic or 

 metalloid bodies, uniting with oxygen to 

 form the earths and alkalies ; namely, 

 sodium, aluminum, magnesium, calcium, 

 lithium, potassium, glucinum, barium, 

 silicium, thorinum, strontium, yttrium, 

 zirconium. Twenty-nine are what are 

 commonly called metals; of these, five, 

 namely, iron, tin, cadmium, zinc, and 

 manganese, decompose water at a red 

 heat ; the others do not decompose water, 

 namely, arsenic, antimony, copper, mo- 

 lybdenum, uranium, tellurium, chromium, 

 cerium, nickel, vanadium, cobalt, lead, 

 tungstenum, titanium, mercury, colum- 

 bium, bismuth, osmium, silver, palla- 



