ART 



ASC 



and condensed, sublimes into a thick 

 liquid, fonnerly called butter of arsenic. 



ARSE'NICAL MINERALS. A class 

 of minerals in which arsenic acts the 

 part of the electro negative element. 

 They occur in primitive districts, and 

 are usually associated with metallic sul- 

 phurets. 



A'RSENOVI'NIC ACID. An acid pro- 

 duced by the action of arsenic upon alcohol. 



A'RSIS and THE'SIS (cipatr, eleva- 

 tion; 6^e(rt9, depression). Technical terras 

 employed in ancient music and ancient 

 metrics. Arsis denoted an elevation of 

 the voice, which is now called metrical 

 accentuation. Thesis was a depression 

 of the voice, and was opposed to arsis. 

 In Music, the terms signified the rising 

 and the falling of the hand in beating 

 time; and hence the Latin word ictus, or 

 stroke, corresponded with arsis. Lastly, 

 per arsin expressed, in Music, a fall from 

 acute to grave ; per thesin, a rise from 

 grave to acute. 



ART and SCIENCE. Art is the ap- 

 plication of knowledge to practical pur- 

 poses. Science is a knowledge of the 

 principles of art. If the knowledge be 

 merely accumulated experience, its ap- 

 plication is empirical art: but if it be 

 experience reasoned upon and brought 

 under general principles, it assumes a 

 higher character, and becomes a scientific 

 art. 



ARTE'RIALIZATION. The conver- 

 sion of the venous into the arterial blood, 

 during its passage through the lungs, 

 by the extrication of carbonic acid, and 

 the absorption of oxygen from the air. 



ARTE'SIAN WELL. A perpendicu- 

 lar perforation of the crust of tlie earth, 

 of small diameter and of great depth, 

 through which water rises to the surface 

 by an artificial jet. The term is derived 

 from Artesium, or Artois. where con- 

 siderable attention has been paid to this 

 means of procuring water. 



ARTHRO'DIAL {'ApOpov, a joint). 

 Belonging to a joint, but restricted to 

 that form of joint in which a ball is re- 

 ceived into a shallow cup, commonly 

 called the ball-and-socket joint. 



A'RTICLE {articuhis, a joint). The 

 name given by grammarians to two 

 words, a or an, and the, which are pre- 

 fixed to ' substantives for the purpose of 

 showing whether they are used in a 

 general sense or in particular relation to 

 an individual. ^« is a corruption of one, 

 and a is a greater corruption of the same 

 adjective. The appears to be derived 

 39 



from the Greek to, through the Gothic 

 sa or tha, and thence through the German 

 der or the Dutch de. 



A'RTICULA'TA {articulus, a joint). 

 Articulated or jointed animals ; one of 

 Cuvier's four great divisions of the Ani- 

 mal Kingdom, in which the skeleton, 

 which is external, is formed of numerous 

 pieces or segments, jointed or articulated 

 together, as in the lobster, the centi- 

 pede, &c. This division corresponds 

 with the Annulosa of Macleay, the 

 Homogangliata of Owen, and the Diplo- 

 neura of Grant. 



ARTOCA'RPE^. The Artocarpus, 

 or Bread-fruit tribe of Dicotyledonous 

 plants; a division of the Urticaceae, or 

 Nettle tribe, distinguished by their con- 

 solidated flowers and milky juice. 



ASBE'STOS (a, priv., a(ievvviJit, to 

 extinguish). A mineral substance, of a 

 fibrous structure, from which an incom- 

 bustible linen is made. There are several 

 varieties, all more or less flexible and 

 fibrous, and termed common asbestos, 

 amianthus, mountain leather and paper, 

 and mountain wood. 



ASCENDING SIGNS. The signs are 

 said to be ascending, when they are east- 

 ward from the meridian, and are, con- 

 sequently, approaching the meridian 

 through the effect of the diurnal rotation 

 of the earth. 



ASCE'NSION, RIGHT (ascendo, to 

 rise). An astronomical term, applied to 

 those arcs in the heavens which corre- 

 spond to longitudes on the earth. Hence 

 the right ascension of a star denotes the 

 arc of the equator intercepted between 

 the first point of Aries and that point of 

 the equator which comes to the meridian 

 at the same instant with the star. 



1. Oblique Ascension is a term nearly 

 out of use. It is an extension of the 

 right ascension to the oblique sphere, in 

 which one pole is above the horizon, and 

 the other below it. The oblique ascen- 

 sion of a star is the arc of the equator 

 intercepted between the vernal equinox 

 and that point of the equator which 

 comes to the horizon at the same time 

 with the star. 



2. Ascensional Difference \s^ also a term 

 nearly out of use. It denotes the dif- 

 ference between the oblique and the right 

 ascensions, and is chiefly used in respect 

 to the sun, because, when the arc which 

 it expresses is turned into time, it shows^ 

 the time before or after six o'clock of 

 sunrise. 



A'SCI {daKo^, a leathern bag). The 



