ARITHMETIC 



31 



ARSENIOUS 



Enaima are divided in Zootoka (Mammalia) 

 and Ootoka (Ovipara). The Zootoka are 

 divided into Dipoda (man), Tetraixxla (quad- 

 rupeds), and Apoda (cetacea); and the Ootoka 

 into Pterota (birds), Pholidota (reptiles), and 

 Lepidota (fishes). 



Arithmetic, (a-rith'me-tik). [Gk. arithmeo, I 

 number.] The science and art of calcula- 

 tion by numbers. 



Arithmetical, (a-rith-met'ik-al). [Arithmetic, 

 q.v.] Kelated to the science of arithmetic. 

 A. mean, the middle term of three terms in 

 arithmetical progression. A. progression, 

 the increase or decrease in a series of num- 

 bers when the same number is continually 

 added or subtracted, as 1, 3, 5, 7, &c., or 15, 

 12, 9, 6, 3, 0. 



Ann, (arm). [The A.-S. word.] 1. The ante- 

 rior limb in man, consisting of the humerus, 

 ulna, radius, and bones of the hand, and 

 accompanying nerves, muscles, &c. 2. The 

 projecting lobes of star-fishes. 3. The ten- 

 tacles of cuttle-fishes, &c. Often used gene- 

 rally for any processes in invertebrate ani- 

 mals. 



Armadillo, (ar-ma-dil'lo). _ [Dim. of Sp. orma- 

 da,anned.]=Dasy- 

 pus : a small bur-. 

 rowing quadruped, 

 found only in Ame- 

 rica, belonging to 

 Edentata, interme- 

 diate between ant- 

 eaters and sloths; Armadillo, 

 having the back and head covered with bony 

 armour plates. 



Armature, (ar'ma-tur). [L. armatus, armed.] 

 1. A piece of soft iron used to connect the 

 poles of a magnet when not in use. 2. A 

 bobbin of wire used to connect the poles of 

 an electro-magnet, and to convey the cur- 

 rent which is generated. 



Armeria, (ar-me'ri-a). [L. flot armeria!, pink.] 

 =Thrift: sea-pink, an herb belonging to 

 Plumbaginacese. 



Armillary sphere, (ar'mil-la-ri). [L. armilla, 

 bracelet.] A number 

 of rings arranged round 

 a centre, so as to repre- 

 sent a sphere : used to 

 illustrate the relative 

 positions of the ecliptic, 

 equator, etc., of the ce- 

 lestial sphere. 



Armoracia, ( ar-mo-rii'- 

 si-a)=Nasturtium am- 

 phibium; alsp=Cochle- 

 aria armoracia=Horse- 

 radish. 



Armorican floral region, Armillary sphere, 

 (ar-mo'rik-an ). Marked by pastures and 

 orchards, extends 

 through S. Eng- 

 land, the Channel 

 Islands, Norman- 

 dy, and Brittany. 



Armstrong gun, 

 (arm'strong). [Sir 

 >V. Armstrong tho Armstrong gun. 



inventor.] A breech-loading rifled gun. v. 

 Gun. 



Arneb, (ar'neb). [The Arabic name.]=a Lepo- 

 ris: the chief star in the constellation Lepus. 



Arnpseris, ( ar-no-se'ris ). [Gk. arnos, lamb; 

 seris, succory.] = Lamb's succory = Swine's 

 succory. A small herb belonging to Cicho- 

 racese. 



Arnut, (ar-nut). [D. aard, earth; noot, nut.] 

 l=Carum bulbocastanum, q.v. 2=Bunium 

 flexuosum, q.v. 



Arnptto=Annatto, q.v. 



Aroideae, ( a-roi'de-c" ) = Arads : herbs with 

 showy flowers: some epiphytous=Araceae, q.v. 



Aromatic, ( ar-o-mat'ik ). [L. aroma, fra- 

 granca] Fragrant. A. acids have the general 

 formula CnHon-gC^. A- alcohols = Benzoic 

 series. A. al'dehyds: oil of cumin, oil of 

 cinnamon, &c. A. hydrocarbons: Benzol, 

 Toluol, Xylol, Cumol, and Cymol, having 

 the general formula CnH 2 n-6- 



Arquerite, (arTte-rit). [Arqueros, in Chili.] 

 An amalgam of silver, found in the mine of 

 Arquerps. 



Arragonite, (ar-rag'o-nlt). [Arragon in Spain.] 

 A mineral, chiefly carbonate of lime. 



Arris, (ar'ris). [F. arete, corner.] = Edge : 

 used especially for intersections of- curved 

 surfaces, as mouldings, &c. A. fillet: used 

 to raise the slates of a roof, to throw off rain. 

 A. gutter: a raised gutter. 



Arrow grasses. [Named from shape of cap- 

 sules.]=Juncaginace8e, q.v.: plants belong- 

 ing to Alismales. 



Arrow head. [Named from shape of leaves.] 

 =Sagittaria, q.v. 



Arrow-root. A variety of starch obtained from 

 the roots of various tropical plants, and used 

 for food. 



Arsenates, ( ar'se-natz ). [Arsenit, q.v.] = 

 Arseniates, q.v. 



Arseniates, (ar-sen'i-atz). [Arsenic, q.v.]= 

 31' 3 As04 : compounds of arsenic acid with a 

 base. 



Arsenic, (ar'sen-ik). [Gk. arsenikos, strong.] 

 =Arsenicum, q.v. A brilliant brittle metal, 

 very poisonous, which is known only as a 

 solid and as a gas, since when heated it 

 volatilises without melting. White A.= 

 Arsenious acidi= Oxide of arsenic. A. anhy- 

 dride = A. acid = AsoOg, Reinsch's test for 

 A.,~by deposit of A. on pure copper. Marsh's 

 test for A., by combination with, nascent 

 hydrogen. 



Arsenic group of minerals: Arsenic, orpi- 

 ment, and realgar, which tinge the blowpipe 

 flame blue. 



Arsenicum, (ar-sen'i-kum). [Arsenic, q.v.]= 

 As"'= Arsenic: one of the phosphorus group 

 of metals: dark-grey, brittle, lustrous, and 

 very poisonous: used for green and yellow 

 pigments, and in glass-making. 



Arsenides, (ar'sen-idz). [Arsenic, q.v.] Com- 

 pounds of arsenic with a base. 



Arsenites, (ar'sen-its). [Arsenic, q.v.] Com- 

 pounds of arsenious acid and a base. 



Arsenious, (ar-seii'i-us). [Arsenic, q.v.] Con- 

 taining arsenic, A. acid A. anhydride= 



