ARO 07 



ARTO'DA, a very brilliant 4,-emu of penta 

 merous coleoptera, belonging to Brazil, 

 closely allied to the cockchafer. 



ARE'otA.Lat. dim. of area. In anatomy, 

 the small interstices of cellular tissues. 

 In Surgery, an inflamed ring around pus- 

 tules, &c. The coloured circle which sur- 

 rounds the nipple of the breast. 



ARE'OL.E, the smaller spaces into which 

 the wings of insects are divided by the 

 nervures. 



ARE'OLATE. 1. In entomology, divided 

 into small spaces. 2. In botany, in com- 

 posite plants, when the florets are placed 

 on the surface of the receptacle, and drop- 

 ping off leave pentagonal spaces. 



AREOLA'TION. Any small space, bounded 

 by something different in colour, tex- 

 ture, &c. 



AREOM'ETER. See ARJEOMETER and HY- 

 DROMETER. 



ARBOM'ETRY, the art of measuring the 

 density or gravity of fluids by means of a 

 hydrometer (generally an areometer). 



AREOPAGUS, the name of the oldest of 

 the Athenian courts of justice, and also 

 the most respectable. The title is derived 

 from A{jf , Mars, and Tyoj, hill. Mars' 

 Hill, a hill in the city on which its first 

 meetings were held. The judges were 

 called areopagitce. 



ARETOI/OGY, a name sometimes given 

 to that part of moral philosophy which 

 treats of virtue, its nature, and the means 

 of attaining it ; from $ETTJ, virtue, and 

 >.fyof , discourse. 



ARGAL, crude tartar, called also argol. 



ARGAN'D. "When a strong light is re- 

 quired from oil or gas, it is common to 

 make a circular burner, with a hole per- 

 forated through the middle for the ad- 

 mission of air into the interior of the 

 flame, and a series of small perforations 

 around the circumference for the egress 

 of gas, or one continuous opening into 

 which the wick is put when it is required 

 to burn oil. Such burners are called ar- 

 gands or argand burners, from the inven- 

 tor's name. 



AROE'MONZ, a genus of Mexican plants. 

 Polyandria Jlonogynia. Name from ar- 

 gema, an ulcer of the eye, which the first 

 known species was said to cure. 



ARGENT, from argentum, silver. The 

 white colour in coats of arms, intended to 

 signify in a woman, chastity ; in a maid, 

 virginity ; injudges,justice,&c. , the rich, 

 humility. 



ARGES'TATE. Fulminating silver is 

 sometimes called argentate of ammonia. 



ARGENTIFEROUS, producing silver, ar- 

 gentum and /pro. 



AR'GENTIKE, resembling silver, argen- 

 tum. Also a name of tlate-tpar, which is 

 a nearly pure sub-spccirs of carbonate of 

 lime, of a slaty structure. The anUmo- 



ARG 



nious acid is popularly termed argentic 

 flotcers of antimony. 



AR'GIL, j Is&t.argilla of i*y/X>.of, white 

 AR'OJLL, ) earth, a^-/of, white. Gene- 

 rally potter's earth, but strictly the earth 

 of clay called in chemistry alumina (q. v.). 

 ARGILLA'CEOCS, of the nature of argil, 

 containing argil. A. earth, alumina, A. 

 schist, clay-slate: ac indurated clay com- 

 mon to the fossilifcrous and metamorphic 

 series. 



AROII/LITE, argillaceous-schist or clay- 

 slate used in roofing houses. 



AR'OOL, crude tartar, called also argal, 

 which when purified is called cream of 

 tartar. 



ARGONir'TA, the paper nautilus or 

 sailor, a sub-genus of sepia or cuttle-fish ; 

 there are several species closely resem- 

 bling each other in animal and shell. 



These mollusca are always found in a 

 very thin shell, symmetrically fluted 

 and spirally convoluted, the last whorl 

 so large that it bears some resem- 

 blance to a galley, of which the spine is 

 the poop. The animal makes a con- 

 stant use of it, and in calm weather 

 whole fleets of them may be observed 

 navigating the surface of the ocean, 

 employing six of their tentacula as oars 

 and elevating the two membraneous 

 ones by way of a sail. If the sea be- 

 comes rough, or they perceive any dan- 

 ger, the argonaut withdraws all its 

 arms, concentrates itself in its shell, 

 takes in water, and descends to tho 

 bottom. There is, however, consider- 

 able doubts whether the animal found 

 within this shell be really the con- 

 structor of it, or a parasitical intruder 

 into a shell formed by some other 

 animal not yet discovered. The animal 

 has no other connection with the shell 

 than that it is found within it, and oc- 

 cupies the last or large whorl only. 

 The others being entirely empty. The 

 name is derived from Afytu, the name 

 of the ship in which Jason sailed to 

 Colchis in search of the golden fleece, 

 and nouns, a sailor. 

 AR'OO-NA'VIS, the ship Argo (JiMon'9 

 ship). The name of a constellation in the 

 southern hemisphere, and type of the 

 ship in which Jason sailed to Colchis. 



AB'GUMENT. Lat. argumentum. In at- 

 tronomy, a quantity upon which another 

 quantity or equation depends, or some 

 circumstance relative to the motion of a 

 planet or satellite ; or it is an arc whereby 

 we endeavour to find another unknown, 

 arc proportional to the first ; hence argu- 

 ment of inclination, called also the argu- 

 ment of latitude, the portion of a planet's 

 orbit intercepted between the ascending 

 node and the place of the planot from the 

 sun, counted according to tlic succession 



