DURAMEN 



109 



EAR 



mater, mother.] A tough fibrous membrane 

 lining the cavity of the skull and spinal 

 column. 



Duramen, (du-ra'men). [L. duramen, hard- 

 ness.] = Heart-wood : the hardest part of 

 the timber of a tree. 



Durene=C6H 2 (CH 3 ) 4 : a hydrocarbon of the 

 benzol series; also called tetra-methyl benzol. 



Durian (du'ri-an). [Malay, dury, thorn.]= 

 Durion : the fruit of Durio 

 zibethinus, which has a 

 thorny covering. 



Durio, (du'ri-o). [Durian, 

 q. v. } A plant of W. Indies, 

 belonging to Bombacese. 



Dusky ant=Formica fusca : 

 a burrowing ant. 



Dust, (dust). [Dus, the Gae- 

 lic word. ] D. fungi = 

 Myxogastres, q.v. : found in 

 tanpits. 



Dutch, (duch). [D. duitsch, popular.] D. clover 

 =Trifolium repens. D. liquid=C^H. 4 ,Cl 2 

 Glycol dichloride=Ethylene dichloride: an 

 aromatic colourless liquid, compounded of ole- 

 fiant gas and chlorine. D. metal=D. leaf: an 

 alloy of brass, with a large admixture of cop- 

 per, beaten out into thin plates. D. roots 

 =Hyacinthus nutans. D. rws/t=Equisetum 

 hyemale. 



Dutchman's-pipe=Tatua morio: a wasp, found 



, in Central America, named from the shape 

 of its nest. 



Duty. D. of steam engine : the amount of 

 work done in relation to the fuel used. 1 

 cwt. of coals will, in burning, produce a force 

 sufficient to raise from 50 to 100 million 

 pounds one foot, according to the efficiency 

 of the engine used. 



Dwale, (dwal)=Atropa=Deadly Nightshade : 

 a poisonous herb, belonging to Solanacepe. 



Dwarf palm=0puntia vulgaris ; also=Cha- 

 morops humilis. 



Dyad, (di'ad). [Gk. dyas, two.]=Diatomic 

 =Bivalent=Chemical elements : one equi- 

 valent of which is equivalent to 2 equivalents 

 of hydrogen in combination. 



Dyads. Elements which unite with,two atoms 

 of hydrogen : the molecule of a dyad is two 

 atoms. 



Dyas, (di'as). A term proposed by M. Marcon 

 for "Permian." 



Dycrasite group=Basic group. 



Dyeing. The change of colour given to 

 woollen or cotton articles by immersion in 

 coloured solutions, with or without the use 

 of a mordant, q.v. 



Dyer's greenwood=D. broom=Genista tinc- 

 toria : a plant belonging to Fabaceae. D. 

 ?ceecZ=Reseda luteola: an herb belonging 

 to Brassicaceae. 



Dyestuffs. Mostly from vegetables, some 

 from animals, some from minerals. 



Dyke, ( dik ). Intrusions of igneous into 

 stratified rocks, usually more or less ver- 

 tical. 



Dynamic, (di-nam'ik). [Gk. dynamis, force.] 

 Relating to forces that produce change of 

 motion in solid bodies. D. absorption = 

 Dynamic cooling, q.v. D. cooling: the cool- 

 ing of a vessel when rapidly exhausted of 

 the contained air. D. energy=Actual energy 

 = Moving force : the force contained in a 



moving body. J). head= ~ , the expression 



for a liquid raised above its natural level by 

 pressure : p=the pressure ; g=the specific 

 gravity of the liquid. D. heating : the 

 heating of an empty vessel by the friction 

 of a liquid or gas entering it. D. radiation 

 ^Dynamic heating, q.v. 



Dynamical, (di-nam'i-kal). [Dynamic, q.v.] 

 D. theory of heat; that it is motion of the 

 ultimate particles of matter, and in no sense 

 material; a form of motion of a minute char- 

 acter. 



Dynamite, (dl'na-mit). [Gk. dynamis, force.] 

 A compound of nitro - glycerine and earth, 

 which is very explosive. 



Dynamometer, (di-na-mom'e-ter)= Indicator : 

 an apparatus which measures energy, e.g., a 

 spring balance. 



Dyne. (din). [Gk. dynamis, force.] Proposed 

 by Everett as an absolute unit of force. 



Dyslysin, ( dis'lis-in ). [Gk. dys, difficult: 

 lysis, solution.] C^H^Og: a resinous in- 

 solubla substance obtained from choloidic 

 acid and hydrochloric acid. 



Dyticidae, ( di-tis'i-de ). [Dyticus, q.v.] A 

 family of water beetles, belonging to Hydra- 

 dephaga, that are first aquatic, then terres- 

 tial, finally amphibious. 



Dyticus. The typical genus of Dyticidse. 



E. 



Eagle, (e'gl). [Aquila, the Latin name..,= 

 Aquila. 1. A powerful diurnal bird of prey, 

 belonging to Falconidse. Bald E. = Ha- 

 liaetus leucocephalus. Booted E.= Aquila 

 pennata. Cinereous J?.:=Haliaetus alicilla. 

 Crested E. =Thrasaetus harpyia. Golden E. 

 =Aquila chrysaetos. Harpy ^.= Crested 

 E., q.v. Martial 2?.=Spizaetus bellicosus. 

 New Holland White #=Astur Novse Hol- 

 landiae. E. Owl=Grea.t Owl^Bubo maxi- 

 m.us. E, stones; a variety of iron ore, 2. 



A constellation in the northern heavens. 

 E. wood : Agila wood, q.v. 



Eagre, (e'ger). [A.-S. eagw, water.] =Bore, q.v. 



Ear, (er). " [Bare, the A.-S. name.] The 

 organ of the sense of hearing ; a very refined 

 modification of the sense of touch, by means 

 of the nerve of hearing, which is sensitive to 

 vibrations between 16 and 38,000 per second. 

 E. shell: Guernsey E.=0rmer; Furrowed E. 

 Stomatia rubra. E. trumpet : an instrument 

 to assist deaf persons in hearing by collecting 



