DIETHYLIN 



102 



DIMETHYIIA 



alkaline liquid=Ammonia, in which two 

 equivalents of hydrogen are replaced by 

 two of ethyl. 



Diethylin, (di-eth'i-lin). [Di and Ethylin, 

 q.v.] = C 3 H5(C 2 H5)2HO3 : a limpid odori- 

 ferous oil, being a compound of glycerin 

 and ethyl. 



Difference tones=Tai?tini's tones : a third 

 tone produced when two different musical 

 notes are sounded, the rate of vibration 

 of which is equal to the difference of the 

 rates of the primary tones. 



Differential, (dif-fer-en'shi-al). [L. differ o, 

 I separate.] D. calculus : the calculation 

 of infinitely small differences. D. coefficient : 

 the limit of the ratio of two variable quan- 

 tities when they become indefinitely small, 



dx d-x 



mitten ^ for the 1st term, ^the 2nd, &c. 



D. equation: an equation containing dif- 

 ferential coefficients. D. screw : two screws 

 of different threads, mounted so that when 

 once turned the force acts through a space 

 equal to the difference of te threads. D. 

 thermometer: for measuring differences of 

 temperatures at the same time. D. tone: 

 difference tones, q.v. D. worm-wheel: a cog- 

 wheel working with a screw on a shaft. 



Differentiation, (dif-fer-en-shi-a'shun). [L. 

 differo, I separate.] 1. The separation into 

 classes according to some specific differenco 

 of structure or nature. 2. The development 

 of two objects, apparently alike, in different 

 directions. 3. The process of obtaining the 

 differential co-efficient of a function with 

 respect to a variable. 



Difflugia, (dif-flu'ji-a). A rhizopod in a mem- 

 braneous sac. 



Diffraction, (dif-frak'shun). [L. diffringo, I 

 break in pieces.] The breaking of a ray of 

 light, heat, or sound into smaller rays. D. 

 of U0ht=lnflexion of light : the formation 

 of coloured fringes when part of a small ray 

 of white light is intercepted by any opaque 

 body ; if the light be of one colour only, the 

 fringes are alternately of that colour and of 

 darkness. D. gratings : a number of parallel 

 lines very close together, which, when light 

 falls on them, produce the colours of the 

 spectrum by diffraction. 



Digastric muscle, ( di-gas'trik ). [Gk. dis, 

 twice ; gaster, belly.] Connecting the mas- 

 toid and mandibles, and having a central 

 tendon separating two muscular portions 

 called bellies. 



Digester, (di-jes'ter). [L. digero, I set in 

 order.] An apparatus for raising water to 

 high temperatures by preventing the escape 

 of the steam. 



Digestion, (di-jest'yun). [L. digero, I set in 

 order.] 1. The treatment of any substance 

 in a digester. 2. The conversion of food into 

 chyme, which takes place in the stomach. 



Digestive, (di-jes'tiv). [Digestion, q.v.] D. 

 system : all the organs used in the assimi- 

 lation of food. In Vertebrata: mouth, 

 stomach, intestines, &c. ; in lower animals 

 it is less complex, and in the lowest very 

 simple. D. cwuwiai!s=Radiata : term used 



by Oken for the lower animals whose chief 

 characteristic is the absorption of food. 



Diggers. Insects belonging to Hymenoptera. 



Digitalis, (dij-it-a'lis). [L. digitalis, belong- 

 ing to the finger.] = Foxglove : an herb 

 with spotted flowers, belonging to Scrophu- 

 lariaceae. 



Digitate, (dij'i-tat). [L. digitatus, having 

 fingers.] Used of leaves, &c., resembling iu 

 form the fingers of a hand. 



Digitigrada, (dij-it-i-gra'da). [L. digitus, 

 finger ; gradior, I walk.] Mammalia which 

 walk on the phalanges or toes, such as the 

 dog, cat, lion, &c. 



Digits, (dij'its). [L. digitus, a finger.]=The 

 fingers. 



Diglycolic acid, (di-gli-kol'ik). [Di and Gly- 

 colic, q.v. ] C^HgOg = Oxidised glycol : a 

 liquid resembling lactic acid. 



Digynia, (di-jin'i-a). [Gk. dis, twice ; gynia, 

 woman.] A sub-division of plants, in the 

 classification by Linnams, including all 

 those that have two styles. 



Digynous, (dij'i-nus). [Digynia, q. v.] Having 

 two styles. 



Diheryl, (dl-heks'il). [Di and Hexyl, q.v.]= 

 Caproyl=Dodecane=(C6Hi3)2 : an aromatic 

 liquid, the radicle of caproic acid. 



Dihydric, (di-hi'drik). [Di and Hydric, q.vj 

 Containing two equivalents of hydrogen. 

 D. 8ulphide=Sa.lphnrettQd hydrogen. D. 

 sulp7iate=Sn.\i>hnric acid. 



Dikakodyl, (di-kak'o-dil). pi and Kakodyl, 

 #.v.]= Kakodyl kakodylido=Kd a : the mole- 

 cular form of kakodyl, q.v. 



Dikes, (diks) [A.-S. die, ditch.] 1. Perpen- 

 dicular walls of trappean rock forced up by 

 volcanic action so as to penetrate softer 

 rocks. 2. Low hills formed by art to keep 

 the water from overflowing land beneath 

 the sea-level. 



Dilactic acid, (di-lak'tik). [Di and Lactic, 

 g.v.]=CgHjoO5 : formerly called lactic an- 

 hydride, a bitter yellow substance obtained 

 by heating lactic acid. 



Dill, (dil)=Anethum graveolens ; a plant 

 belonging to Apiacese. 



DUleniacesB, (dil-len-i-a'se-e). [J. J. Dillenius, 

 a botanist. ]=Dilleniads : trees and shrubs, 

 chiefly tropical, with leathery leaves and 

 solitary flowers, belonging to Kanales. 



Dillesh, (dillesh). An edible sea- weed, found 

 on the coast of Ireland. 



Diluvium, ( di-lu'vi-um ). [L. diluvium, a 

 flood.] An old name for boulder formation, 

 q.v. 



Dimeracanthus, ( di-mer-a-kan'thus ). [ Gk. 

 di, two ; meris, cleft ; akantha, spine.] A 

 plagiostomous fish, known only by fossil 

 spines, found in Devonian rocks. 



Dimethyl, (dl-meth'il). [Di and Methyl, q.v.] 

 =(CH 3 ) 2 = Methyl methylide = Ethyl hy- 

 dride : a combustible gas, the molecular form 

 of methyl, q.v. 



Dimethylia, (di-meth-ili-a). (Di and Methy- 

 lia, g.7;.]=(CH3) 2 HN : a base obtained by 

 compounding acetic aldehyd and ammonia 

 =Ammonia in which two equivalents of 

 hydrogen are replaced by two of methyl. 



